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href="command-line-options.html#stroke">&#x2011;stroke</a>  • <a href="command-line-options.html#strokewidth">&#x2011;strokewidth</a>  • <a href="command-line-options.html#style">&#x2011;style</a>  • <a href="command-line-options.html#subimage-search">&#x2011;subimage&#x2011;search</a>  • <a href="command-line-options.html#swap">&#x2011;swap</a>  • <a href="command-line-options.html#swirl">&#x2011;swirl</a>  • <a href="command-line-options.html#synchronize">&#x2011;synchronize</a>  • <a href="command-line-options.html#taint">&#x2011;taint</a>  • <a href="command-line-options.html#text-font">&#x2011;text&#x2011;font</a>  • <a href="command-line-options.html#texture">&#x2011;texture</a>  • <a href="command-line-options.html#threshold">&#x2011;threshold</a>  • <a href="command-line-options.html#thumbnail">&#x2011;thumbnail</a>  • <a href="command-line-options.html#tile">&#x2011;tile</a>  • <a href="command-line-options.html#tile-offset">&#x2011;tile&#x2011;offset</a>  • <a href="command-line-options.html#tint">&#x2011;tint</a>  • <a href="command-line-options.html#title">&#x2011;title</a>  • <a href="command-line-options.html#transform">&#x2011;transform</a>  • <a href="command-line-options.html#transparent">&#x2011;transparent</a>  • <a href="command-line-options.html#transparent-color">&#x2011;transparent&#x2011;color</a>  • <a href="command-line-options.html#transpose">&#x2011;transpose</a>  • <a href="command-line-options.html#transverse">&#x2011;transverse</a>  • <a href="command-line-options.html#treedepth">&#x2011;treedepth</a>  • <a href="command-line-options.html#trim">&#x2011;trim</a>  • <a href="command-line-options.html#type">&#x2011;type</a>  • <a href="command-line-options.html#undercolor">&#x2011;undercolor</a>  • <a href="command-line-options.html#unique-colors">&#x2011;unique&#x2011;colors</a>  • <a href="command-line-options.html#units">&#x2011;units</a>  • <a href="command-line-options.html#unsharp">&#x2011;unsharp</a>  • <a href="command-line-options.html#update">&#x2011;update</a>  • <a href="command-line-options.html#verbose">&#x2011;verbose</a>  • <a href="command-line-options.html#version">&#x2011;version</a>  • <a href="command-line-options.html#view">&#x2011;view</a>  • <a href="command-line-options.html#vignette">&#x2011;vignette</a>  • <a href="command-line-options.html#virtual-pixel">&#x2011;virtual&#x2011;pixel</a>  • <a href="command-line-options.html#visual">&#x2011;visual</a>  • <a href="command-line-options.html#watermark">&#x2011;watermark</a>  • <a href="command-line-options.html#wave">&#x2011;wave</a>  • <a href="command-line-options.html#wavelet-denoise">&#x2011;wavelet&#x2011;denoise</a>  • <a href="command-line-options.html#weight">&#x2011;weight</a>  • <a href="command-line-options.html#white-point">&#x2011;white&#x2011;point</a>  • <a href="command-line-options.html#white-threshold">&#x2011;white&#x2011;threshold</a>  • <a href="command-line-options.html#window">&#x2011;window</a>  • <a href="command-line-options.html#window-group">&#x2011;window&#x2011;group</a>  • <a href="command-line-options.html#write">&#x2011;write</a>  • <a href="command-line-options.html#write-mask">&#x2011;write&#x2011;mask</a>  </p>
85<p class="lead magick-description">Below is list of command-line options recognized by the ImageMagick <a href="command-line-tools.html">command-line tools</a>. If you want a description of a particular option, click on the option name in the navigation bar above and you will go right to it. Unless otherwise noted, each option is recognized by the commands: <a href="convert.html">convert</a> and <a href="mogrify.html">mogrify</a>.</p>
86
87<div style="margin: auto;">
88  <h3><a class="anchor" id="adaptive-blur"></a>-adaptive-blur <var>radius</var>[x<var>sigma</var>]</h3>
89</div>
90
91<p class="magick-description">Adaptively blur pixels, with decreasing effect near edges.</p>
92
93<p>A Gaussian operator of the given radius and standard deviation (<var>sigma</var>) is used. If <var>sigma</var> is not given it
94defaults to 1.</p>
95
96<div style="margin: auto;">
97  <h3><a class="anchor" id="adaptive-resize"></a>-adaptive-resize <var>geometry</var></h3>
98</div>
99
100<p class="magick-description">Resize the image using data-dependent triangulation.</p>
101
102<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <a href="command-line-options.html#adaptive-resize">-adaptive-resize</a>
103option defaults to data-dependent triangulation.  Use the <a
104href="command-line-options.html#filter">-filter</a> to choose a different resampling algorithm.
105Offsets, if present in the geometry string, are ignored, and the <a
106href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
107
108<div style="margin: auto;">
109  <h3><a class="anchor" id="adaptive-sharpen"></a>-adaptive-sharpen <var>radius</var>[x<var>sigma</var>]</h3>
110</div>
111
112<p class="magick-description">Adaptively sharpen pixels, with increasing effect near edges.</p>
113
114<p>A Gaussian operator of the given radius and standard deviation
115(<var>sigma</var>) is used. If <var>sigma</var> is not given it
116defaults to 1.</p>
117
118<div style="margin: auto;">
119  <h3><a class="anchor" id="adjoin"></a>-adjoin</h3>
120</div>
121
122<p class="magick-description">Join images into a single multi-image file.</p>
123
124<p>This option is enabled by default. An attempt is made to save all images of
125an image sequence into the given output file.  However, some formats, such as
126JPEG and PNG, do not support more than one image per file, and in that case
127ImageMagick is forced to write each image as a separate file.  As such, if
128more than one image needs to be written, the filename given is modified by
129adding a <a href="command-line-options.html#scene">-scene</a> number before the suffix, in order to
130make distinct names for each image. </p>
131
132<p>Use <a href="command-line-options.html#adjoin">+adjoin</a> to force each image to be written to
133separate files, whether or not the file format allows multiple images per file
134(for example, GIF, MIFF, and TIFF). </p>
135
136<p>Including a C-style integer format string in the output filename will
137automagically enable <a href="command-line-options.html#adjoin">+adjoin</a> and are used to specify
138where the <a href="command-line-options.html#scene">-scene</a> number is placed in the filenames. These
139strings, such as '<code>%d</code>' or '<code>%03d</code>', are familiar to those
140who have used the standard <code>printf()</code>' C-library function. As an
141example, the command</p>
142
143<pre class="highlight"><code>convert logo: rose: -morph 15 my%02dmorph.jpg
144</code></pre>
145
146<p>will create a sequence of 17 images (the two given plus 15 more created by
147<a href="command-line-options.html#morph">-morph</a>), named: my00morph.jpg, my01morph.jpg,
148my02morph.jpg, ..., my16morph.jpg.  </p>
149
150<p>In summary, ImageMagick tries to write all images to one file, but will
151save to multiple files, if any of the following conditions exist...</p>
152<ol>
153<li>the output image's file format does not allow multi-image files,</li>
154<li>the <a href="command-line-options.html#adjoin">+adjoin</a> option is given, or</li>
155<li>a printf() integer format string (eg: "%d") is present in the output
156 filename.</li>
157</ol>
158
159
160<div style="margin: auto;">
161  <h3><a class="anchor" id="affine"></a>-affine
162  <var>s<sub>x</sub></var>,<var>r<sub>x</sub></var>,<var>r<sub>y</sub></var>,<var>s<sub>y</sub></var>[,<var>t<sub>x</sub></var>,<var>t<sub>y</sub></var>]</h3>
163</div>
164
165<p class="magick-description">Set the drawing transformation matrix for combined rotating and scaling.</p>
166
167<p>This option sets a transformation matrix, for use by subsequent <a
168href="command-line-options.html#draw">-draw</a> or <a href="command-line-options.html#transform">-transform</a> options. </p>
169
170<p>The matrix entries are entered as comma-separated numeric values either in
171quotes or without spaces. </p>
172
173<p>Internally, the transformation matrix has 3x3 elements, but three of them
174are omitted from the input because they are constant. The new (transformed)
175coordinates (<var>x'</var>, <var>y'</var>) of a pixel at
176position (<var>x</var>, <var>y</var>) in the original
177image are calculated using the following matrix equation.</p>
178
179<p class="text-center"><img class="img-thumbnail" alt="affine transformation"  src="../images/affine.png"/> </p>
180
181<p> The size of the resulting image is that of the smallest rectangle that
182contains the transformed source image.  The parameters
183<var>t<sub>x</sub></var> and <var>t<sub>y</sub></var>
184subsequently shift the image pixels so that those that are moved out of the
185image area are cut off.</p>
186
187<p>The transformation matrix complies with the left-handed pixel coordinate
188system: positive <var>x</var> and <var>y</var> directions
189are rightward and downward, resp.; positive rotation is clockwise.</p>
190
191<p> If the translation coefficients <var>t<sub>x</sub></var> and
192<var>t<sub>y</sub></var> are omitted they default to 0,0. Therefore,
193four parameters suffice for rotation and scaling without translation.</p>
194
195<p>Scaling by the factors <var>s<sub>x</sub></var> and
196<var>s<sub>y</sub></var> in the <var>x</var> and <var>y</var> directions,
197respectively, is accomplished with the following.</p>
198
199<p>See <a href="command-line-options.html#transform">-transform</a>, and the <a
200href="command-line-options.html#distort">-distort</a> method '<code>Affineprojection</code> for more
201information </p>
202
203
204<pre class="highlight"><code>-affine <var>s<sub>x</sub></var>,0,0,<var>s<sub>y</sub></var>
205</code></pre>
206
207<p>Translation by a displacement (<var>t<sub>x</sub></var>, <var>t<sub>y</sub></var>) is accomplished like so:</p>
208
209<pre class="highlight"><code>-affine 1,0,0,1,<var>t<sub>x</sub></var>,<var>t<sub>y</sub></var>
210</code></pre>
211
212<p>Rotate clockwise about the origin (the upper left-hand corner) by an angle
213<var>a</var> by letting <var>c</var> = cos(<var>a</var>), <var>s</var>
214= sin(<var>a</var>), and using the following.</p>
215
216<pre class="highlight"><code>-affine <var>c</var>,<var>s</var>,-<var>s</var>,<var>c</var>
217</code></pre>
218
219<p>The cumulative effect of a sequence of <a href="command-line-options.html#affine" >-affine</a>
220transformations can be accomplished by instead by a single <a href="command-line-options.html#affine"
221>-affine</a> operation using the matrix equal to the product of the matrices
222of the individual transformations.</p>
223
224<p>An attempt is made to detect near-singular transformation matrices. If the
225matrix determinant has a sufficiently small absolute value it is rejected.</p>
226
227<div style="margin: auto;">
228  <h3><a class="anchor" id="alpha"></a>-alpha <var>type</var></h3>
229</div>
230
231<p class="magick-description">Gives control of the alpha/matte channel of an image.</p>
232
233<p>Used to set a flag on an image indicating whether or not to use existing alpha
234channel data, to create an alpha channel, or to perform other operations on the alpha channel.  Choose the argument <var>type</var> from the list below.</p>
235
236<dl class="row">
237    <dt class="col-md-4">Activate</dt>
238    <dd class="col-md-8">
239       Enable the image's transparency channel. Note normally Set
240       should be used instead of this, unless you specifically need to
241       preserve existing (but specifically turned Off) transparency
242       channel. </dd>
243
244    <dt class="col-md-4">Associate</dt>
245    <dd class="col-md-8">
246       associate the alpha channel with the image.</dd>
247
248    <dt class="col-md-4">Deactivate</dt>
249    <dd class="col-md-8">
250       Disables the image's transparency channel. Does not delete or change the
251       existing data, just turns off the use of that data.</dd>
252
253    <dt class="col-md-4">Disassociate</dt>
254    <dd class="col-md-8">
255       disassociate the alpha channel from the image.</dd>
256
257    <dt class="col-md-4">Set</dt>
258    <dd class="col-md-8">
259       Activates the alpha/matte channel. If it was previously turned off
260       then it also resets the channel to opaque.  If the image already had
261       the alpha channel turned on, it will have no effect.</dd>
262
263    <dt class="col-md-4">Opaque</dt>
264    <dd class="col-md-8">
265       Enables the alpha/matte channel and forces it to be fully opaque.
266       </dd>
267
268    <dt class="col-md-4">Transparent</dt>
269    <dd class="col-md-8">
270       Activates the alpha/matte channel and forces it to be fully
271       transparent. This effectively creates a fully transparent image the
272       same size as the original and with all its original RGB data still
273       intact, but fully transparent. </dd>
274
275    <dt class="col-md-4">Extract</dt>
276    <dd class="col-md-8">
277       Copies the alpha channel values into all the color channels and turns
278       'Off' the the image's transparency, so as to generate
279       a grayscale mask of the image's shape. The alpha channel data is left
280       intact just deactivated.  This is the inverse of 'Copy'.
281       </dd>
282
283    <dt class="col-md-4">Copy</dt>
284    <dd class="col-md-8">
285       Turns 'On' the alpha/matte channel, then copies the
286       grayscale intensity of the image, into the alpha channel, converting
287       a grayscale mask into a transparent shaped mask ready to be colored
288       appropriately. The color channels are not modified.  </dd>
289
290    <dt class="col-md-4">Shape</dt>
291    <dd class="col-md-8">
292       As per 'Copy' but also colors the resulting shape mask with
293       the current background color.  That is the RGB color channels is
294       replaced, with appropriate alpha shape.
295       </dd>
296
297    <dt class="col-md-4">Remove</dt>
298    <dd class="col-md-8">
299       Composite the image over the background color.
300       </dd>
301
302    <dt class="col-md-4">Background</dt>
303    <dd class="col-md-8">
304       Set any fully-transparent pixel to the background color, while leaving
305       it fully-transparent.  This can make some image file formats, such as
306       PNG, smaller as the RGB values of transparent pixels are more uniform,
307       and thus can compress better.
308       </dd>
309</dl>
310
311<p>Note that while the obsolete <code>+matte</code> operation was the
312same as "<code><a href="command-line-options.html#alpha" >-alpha</a> Off</code>", the <code>
313>-matte</code> operation was the same as "<code><a href="command-line-options.html#alpha" >-alpha</a>
314Set</code>" and not "<code><a href="command-line-options.html#alpha" >-alpha</a> On</code>".  </p>
315
316<div style="margin: auto;">
317 <h3><a class="anchor" id="annotate"></a>
318 -annotate <var>degrees</var> <var>text</var><br />
319 -annotate <var>Xdegrees</var>x<var>Ydegrees</var> <var>text</var><br /> -annotate <var>Xdegrees</var>x<var>Ydegrees</var> {+-}<var>t<sub>x</sub></var>{+-}<var>t<sub>y</sub></var> <var>text</var><br /> -annotate {+-}<var>t<sub>x</sub></var>{+-}<var>t<sub>y</sub></var> <var>text</var></h3>
320</div>
321
322<p class="magick-description">Annotate an image with text</p>
323
324<p>This is a convenience for annotating an image with text. For more precise
325control over text annotations, use <a href="command-line-options.html#draw">-draw</a>.</p>
326
327
328<p>The values <var>Xdegrees</var> and <var>Ydegrees</var>
329control the shears applied to the text, while <var>t<sub>x</sub></var> and <var>t<sub>y</sub></var> are offsets that give the location of the text relative any <a href="command-line-options.html#gravity" >-gravity</a> setting and defaults to the upper left corner of the image.</p>
330
331<p>Using <a href="command-line-options.html#annotate">-annotate</a> <var>degrees</var>
332or <a href="command-line-options.html#annotate">-annotate</a> <var>degrees</var>x<var>degrees</var> produces an unsheared rotation of the text. The
333direction of the rotation is positive, which means a clockwise rotation if <var>degrees</var> is positive. (This conforms to the usual mathematical
334convention once it is realized that the positive <var>y</var>–direction is
335conventionally considered to be <var>downward</var> for images.)</p>
336
337<p>The new (transformed) coordinates (<var>x'</var>, <var>y'</var>) of a pixel at position (<var>x</var>, <var>y</var>) in the image are calculated using the following matrix
338equation.</p>
339
340<p class="text-center"><img class="img-thumbnail" alt="annotate transformation"  src="../images/annotate.png"/></p>
341
342<p>If <var>t<sub>x</sub></var> and <var>t<sub>y</sub></var> are omitted, they default to 0. This makes the
343bottom-left of the text becomes the upper-left corner of the image, which is
344probably undesirable. Adding a <a href="command-line-options.html#gravity" >-gravity</a> option in this
345case leads to nice results.</p>
346
347<p>Text is any UTF-8 encoded character sequence.  If <var>text</var>
348is of the form '@mytext.txt', the text is read from the file
349<code>mytext.txt</code>.  Text  in a file is taken literally; no embedded
350formatting characters are recognized.</p>
351
352<div style="margin: auto;">
353  <h3><a class="anchor" id="antialias"></a>-antialias</h3>
354</div>
355
356<p class="magick-description">Enable/Disable of the rendering of anti-aliasing pixels when drawing fonts and lines.</p>
357
358<p>By default, objects (e.g. text, lines, polygons, etc.) are antialiased when
359drawn.  Use <a href="command-line-options.html#antialias">+antialias</a> to disable the addition of
360antialiasing edge pixels.  This will then reduce the number of colors added to
361an image to just the colors being directly drawn.  That is, no mixed colors
362are added when drawing such objects. </p>
363
364<div style="margin: auto;">
365  <h3><a class="anchor" id="append"></a>-append</h3>
366</div>
367
368<p class="magick-description">Join current images vertically or horizontally.</p>
369
370<p>This option creates a single longer image, by joining all the current
371images in sequence top-to-bottom. Use <a href="command-line-options.html#append">+append</a> to
372stack images left-to-right. </p>
373
374<p>If they are not of the same width, narrower images are padded with the
375current <a href="command-line-options.html#background">-background</a> color setting, and their
376position relative to each other can be controlled by the current <a
377href="command-line-options.html#gravity">-gravity</a> setting. </p>
378
379
380<div style="margin: auto;">
381  <h3><a class="anchor" id="attenuate"></a>-attenuate <var>value</var></h3>
382</div>
383
384<p class="magick-description">Lessen (or intensify) when adding noise to an image.</p>
385
386<p>If unset the value is equivalent to 1.0, or a maximum noise addition</p>
387
388<div style="margin: auto;">
389  <h3><a class="anchor" id="authenticate"></a>-authenticate <var>password</var></h3>
390</div>
391
392<p class="magick-description">Decrypt a PDF with a password.</p>
393
394<p>Use this option to supply a <var>password</var> for decrypting
395a PDF that has been encrypted using Microsoft Crypto API (MSC API). The
396encrypting using the MSC API is not supported.</p>
397
398<p>For a different encryption method, see <a href="command-line-options.html#encipher">-encipher</a>
399and <a href="command-line-options.html#decipher">-decipher</a>. </p>
400
401
402<div style="margin: auto;">
403  <h3><a class="anchor" id="auto-gamma"></a>-auto-gamma</h3>
404</div>
405
406<p class="magick-description">Automagically adjust gamma level of image.</p>
407
408<p>This calculates the mean values of an image, then applies a calculated  <a
409href="command-line-options.html#gamma" >-gamma</a> adjustment so that the mean color in the
410image will get a value of 50%. </p>
411
412<p>This means that any solid 'gray' image becomes 50% gray. </p>
413
414<p>This works well for real-life images with little or no extreme dark and
415light areas, but tend to fail for images with large amounts of bright sky or
416dark shadows. It also does not work well for diagrams or cartoon like images.
417</p>
418
419<p>It uses the <a href="command-line-options.html#channel" >-channel</a> setting, (including the
420'<var>sync</var>' flag for channel synchronization), to determine which color
421values is used and modified. As the default <a href="command-line-options.html#channel"
422>-channel</a> setting is '<var>RGB,sync</var>', channels are modified
423together by the same gamma value, preserving colors. </p>
424
425
426
427<div style="margin: auto;">
428  <h3><a class="anchor" id="auto-level"></a>-auto-level</h3>
429</div>
430
431<p class="magick-description">Automagically adjust color levels of image.</p>
432
433<p>This is a 'perfect' image normalization operator.  It finds the exact
434minimum and maximum color values in the image and then applies a <a
435href="command-line-options.html#level" >-level</a> operator to stretch the values to the full range of
436values. </p>
437
438<p>The operator is not typically used for real-life images, image scans, or
439JPEG format images, as a single 'out-rider' pixel can set a bad min/max values
440for the <a href="command-line-options.html#level" >-level</a> operation.  On the other hand it is the
441right operator to use for color stretching gradient images being used to
442generate Color lookup tables, distortion maps, or other 'mathematically'
443defined images.  </p>
444
445<p>The operator is very similar to the <a href="command-line-options.html#normalize">-normalize</a>, <a
446href="command-line-options.html#contrast-stretch" >-contrast-stretch</a>, and <a href="command-line-options.html#linear-stretch"
447>-linear-stretch</a> operators, but without 'histogram binning' or 'clipping'
448problems that these operators may have. That is <a href="command-line-options.html#auto-level"
449>-auto-level</a> is the perfect or ideal version these operators. </p>
450
451<p>It uses the <a href="command-line-options.html#channel" >-channel</a> setting, (including the
452special '<var>sync</var>' flag for channel synchronization), to determine
453which color values are used and modified. As the default <a
454href="command-line-options.html#channel" >+channel</a> setting is '<var>RGB,sync</var>', the
455'<var>sync</var>' ensures that the color channels will are modified
456together by the same gamma value, preserving colors, and ignoring
457transparency. </p>
458
459
460<div style="margin: auto;">
461  <h3><a class="anchor" id="auto-orient"></a>-auto-orient</h3>
462</div>
463
464<p class="magick-description">adjusts an image so that its orientation is suitable for viewing (i.e. top-left orientation).</p>
465
466<p>This operator reads and resets the EXIF image profile setting 'Orientation'
467and then performs the appropriate 90 degree rotation on the image to orient
468the image, for correct viewing. </p>
469
470<p>This EXIF profile setting is usually set using a gravity sensor in digital
471camera, however photos taken directly downward or upward may not have an
472appropriate value.  Also images that have been orientation 'corrected' without
473reseting this setting, may be 'corrected' again resulting in a incorrect
474result.  If the EXIF profile was previously stripped, the  <a
475href="command-line-options.html#auto-orient" >-auto-orient</a> operator will do nothing. </p>
476
477<div style="margin: auto;">
478  <h3><a class="anchor" id="auto-threshold"></a>-auto-threshold <var>method</var></h3>
479</div>
480
481<p class="magick-description">automatically perform image thresholding.</p>
482
483<p>Here are the valid methods:</p>
484
485<dl class="row">
486<dt class="col-md-4">Undefined</dt><dd class="col-md-8">0:  No method specified (equivalent to '<code>OTSU</code>').</dd>
487<dt class="col-md-4">Kapur</dt><dd class="col-md-8">maximum entropy thresholding.</dd>
488<dt class="col-md-4">OTSU</dt><dd class="col-md-8">cluster-based image thresholding.</dd>
489<dt class="col-md-4">Triangle</dt><dd class="col-md-8">a geometric thresholding method.</dd>
490</dl>
491
492<p>The computed threshold is returned as the <kbd>auto-threshold:threshold</kbd> image property.</p>
493
494<div style="margin: auto;">
495  <h3><a class="anchor" id="average"></a>-average</h3>
496</div>
497
498<p class="magick-description">Average a set of images.</p>
499
500<p>An error results if the images are not identically sized.</p>
501
502
503<div style="margin: auto;">
504  <h3><a class="anchor" id="backdrop"></a>-backdrop</h3>
505</div>
506
507<p class="magick-description">Display the image centered on a backdrop.</p>
508
509<p>This backdrop covers the entire workstation screen and is useful for hiding
510other X window activity while viewing the image. The color of the backdrop is
511specified as the background color. The color is specified using the format
512described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
513
514<div style="margin: auto;">
515  <h3><a class="anchor" id="background"></a>-background <var>color</var></h3>
516</div>
517
518<p class="magick-description">Set the background color.</p>
519
520<p>The color is specified using the format described under the <a
521href="command-line-options.html#fill">-fill</a> option. The default background color (if none is
522specified or found in the image) is white.</p>
523
524<div style="margin: auto;">
525  <h3><a class="anchor" id="bench"></a>-bench <var>iterations</var></h3>
526</div>
527
528<p class="magick-description">Measure performance.</p>
529
530<p>Repeat the entire command for the given number of <var>iterations</var> and report the user-time and elapsed time. For instance,
531consider the following command and its output.  Modify the benchmark with the
532-duration to run the benchmark for a fixed number of seconds and -concurrent
533to run the benchmark in parallel (requires the OpenMP feature).</p>
534
535<pre class="highlight"><code>-> convert logo: -resize 200% -bench 5 logo.png
536Performance[1]: 5i 1.344ips 1.000e 3.710u 0:03.720
537Performance[2]: 5i 1.634ips 0.549e 3.890u 0:03.060
538Performance[3]: 5i 2.174ips 0.618e 3.190u 0:02.300
539Performance[4]: 5i 1.678ips 0.555e 3.810u 0:02.980
540Performance[4]: 5i 0.875657ips 6.880u 0:05.710
541</code></pre>
542
543<p>In this example, 5 iterations were completed at 2.174 iterations per
544second, using 3 threads and 3.190 seconds of the user allotted time, for
545a total elapsed time of 2.300 seconds.</p>
546
547<div style="margin: auto;">
548  <h3><a class="anchor" id="bias"></a>-bias <var>value</var>{<var>%</var>}</h3>
549</div>
550
551<p class="magick-description">Add bias when convolving an image.</p>
552
553<p>This option shifts the output of <a href="command-line-options.html#convolve">&#x2011;convolve</a>  so that
554positive and negative results are relative to the specified bias value. </p>
555
556<p>This is important for non-HDRI compilations of ImageMagick when dealing
557with convolutions that contain negative as well as positive values. This is
558especially the case with convolutions involving high pass filters or edge
559detection. Without an output bias, the negative values are clipped at
560zero.</p>
561
562<p>When using an ImageMagick with the HDRI compile-time setting, <a href="command-line-options.html#bias">&#x2011;bias</a> is not needed, as ImageMagick is able to store/handle any
563negative results without clipping to the color value range
564(0..QuantumRange).</p>
565
566<p>See the discussion on HDRI implementations of ImageMagick on the page <a
567href="high-dynamic-range.html" >High Dynamic-Range Images</a>. For more
568about HDRI go the ImageMagick <a
569href="../Usage/basics/#hdri" >Usage</a> pages or this
570<a
571href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
572entry.  </p>
573
574<div style="margin: auto;">
575  <h3><a class="anchor" id="black-point-compensation"></a>-black-point-compensation</h3>
576</div>
577
578<p class="magick-description">Use black point compensation.</p>
579
580<div style="margin: auto;">
581  <h3><a class="anchor" id="black-threshold"></a>-black-threshold <var>value</var>{<var>%</var>}</h3>
582</div>
583
584<p class="magick-description">Force to black all pixels below the threshold while leaving all pixels at or above the threshold unchanged.</p>
585
586<p> The threshold value can be given as a percentage or as an absolute integer
587value within [0, <var>QuantumRange</var>] corresponding to the
588desired <a href="command-line-options.html#channel">&#x2011;channel</a> value. See <a href="command-line-options.html#threshold">&#x2011;threshold</a>for more details on thresholds and resulting values.  </p>
589
590
591<div style="margin: auto;">
592  <h3><a class="anchor" id="blend"></a>-blend <var>geometry</var></h3>
593</div>
594
595<p class="magick-description">blend an image into another by the given absolute value or percent.</p>
596
597<p>Blend will average the images together ('plus') according to the
598percentages given and each pixels transparency.  If only a single percentage
599value is given it sets the weight of the composite or 'source' image, while
600the background image is weighted by the exact opposite amount. That is a
601<code>-blend 30%</code> merges 30% of the 'source' image with 70% of the
602'destination' image.  Thus it is equivalent to <code>-blend 30x70%</code>.</p>
603
604
605<div style="margin: auto;">
606  <h3><a class="anchor" id="blue-primary"></a>-blue-primary <var>x</var>,<var>y</var></h3>
607</div>
608
609<p class="magick-description">Set the blue chromaticity primary point.</p>
610
611<div style="margin: auto;">
612  <h3><a class="anchor" id="blue-shift"></a>-blue-shift <var>factor</var></h3>
613</div>
614
615<p class="magick-description">simulate a scene at nighttime in the moonlight.  Start with a factor of 1.5</p>
616
617<div style="margin: auto;">
618
619<div style="margin: auto;">
620  <h3><a class="anchor" id="blur"></a>-blur <var>radius</var><br />-blur <var>radius</var>x<var>sigma</var></h3>
621</div>
622
623<p class="magick-description">Reduce image noise and reduce detail levels.</p>
624
625<p>Convolve the image with a Gaussian or normal distribution using the given
626<var >Sigma</var> value.  The formula is:</p>
627
628<p class="text-center"><img class="img-thumbnail" alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"/></p>
629
630<p>The <var >Sigma</var> value is the important argument, and
631determines the actual amount of blurring that will take place. </p>
632
633<p>The <var >Radius</var> is only used to determine the size of the
634array which will hold the calculated Gaussian distribution. It should be an
635integer.  If not given, or set to zero, IM will calculate the largest possible
636radius that will provide meaningful results for the Gaussian distribution.
637</p>
638
639<p>The larger the <var >Radius</var> the slower the
640operation is. However too small a <var >Radius</var>, and severe
641aliasing effects may result.  As a guideline, <var >Radius</var>
642should be at least twice the <var >Sigma</var> value, though three
643times will produce a more accurate result. </p>
644
645<p>This option differs from <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a> simply
646by taking advantage of the separability properties of the distribution.  Here
647we apply a single-dimensional Gaussian matrix in the horizontal direction,
648then repeat the process in the vertical direction.</p>
649
650<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
651pixels which are outside the image proper are blurred into the final result.
652</p>
653
654
655<div style="margin: auto;">
656  <h3><a class="anchor" id="border"></a>-border <var>geometry</var></h3>
657</div>
658
659<p class="magick-description">Surround the image with a border of color. </p>
660
661<p>Set the width and height using the <var>size</var> portion of the
662<var>geometry</var> argument.  See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets are
663ignored. </p>
664
665<p>As of IM 6.7.8-8, the <var>geometry</var> arguments behave as follows:</p>
666
667<dl class="row">
668<dt class="col-md-4"><var>value</var></dt>
669<dd class="col-md-8">value is added to both left/right and top/bottom</dd>
670<dt class="col-md-4"><var>value-x</var><code>x</code></dt>
671<dd class="col-md-8">value-x is added only to left/right and top/bottom are unchanged</dd>
672<dt class="col-md-4"><code>x</code><var>value-y</var></dt>
673<dd class="col-md-8">value-y is added only to top/bottom and left/right are unchanged</dd>
674<dt class="col-md-4"><var>value-x</var><code>x</code><var>value-y</var></dt>
675<dd class="col-md-8">value-x is added to left/right and value-y added to top/bottom</dd>
676<dt class="col-md-4"><var>value-x</var><code>x</code>0</dt>
677<dd class="col-md-8">value-x is added only to left/right and top/bottom are unchanged</dd>
678<dt class="col-md-4">0<code>x</code><var>value-y</var></dt>
679<dd class="col-md-8">value-y is added only to top/bottom and left/right are unchanged</dd>
680<dt class="col-md-4"><var>value</var>%</dt>
681<dd class="col-md-8">value % of width is added to left/right and value % of height is added to top/bottom</dd>
682<dt class="col-md-4"><var>value-x</var><code>x</code>%</dt>
683<dd class="col-md-8">value-x % of width is added to left/right and to top/bottom</dd>
684<dt class="col-md-4">x<var>value-y</var>%</dt>
685<dd class="col-md-8">value-y % of height is added to top/bottom and to left/right</dd>
686<dt class="col-md-4"><var>value-x</var>%<code>x</code><var>value-y</var>%</dt>
687<dd class="col-md-8">value-x % of width is added to left/right and value-y % of height is added to top/bottom</dd>
688<dt class="col-md-4"><var>value-x</var>%<code>x</code>0%</dt>
689<dd class="col-md-8">value-x % of width is added to left/right and top/bottom are unchanged</dd>
690<dt class="col-md-4">0%<code>x</code><var>value-y</var>%</dt>
691<dd class="col-md-8">value-y % of height is added to top/bottom and left/right are unchanged</dd>
692</dl>
693
694<p>Set the border color by preceding with the <a
695href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
696
697<p>The <a href="command-line-options.html#border">-border</a> operation is affected by the current <a
698href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
699'<code>Over</code>' composition method.  It generates an image of the appropriate
700size colors by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> before
701overlaying the original image in the center of this net image.  This means that
702with the default compose method of '<code>Over</code>' any transparent parts may
703be replaced by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
704<p>See also the <a href="command-line-options.html#frame">-frame</a> option, which has more
705functionality.</p>
706
707<div style="margin: auto;">
708  <h3><a class="anchor" id="bordercolor"></a>-bordercolor <var>color</var></h3>
709</div>
710
711<p class="magick-description">Set the border color.</p>
712
713<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
714
715<p>The default border color is <code>#DFDFDF</code>, <span style="background-color: #dfdfdf;">this shade of gray</span>.</p>
716
717<div style="margin: auto;">
718  <h3><a class="anchor" id="borderwidth"></a>-borderwidth <var>geometry</var> </h3>
719</div>
720
721<p class="magick-description">Set the border width.</p>
722
723<div style="margin: auto;">
724  <h3><a class="anchor" id="brightness-contrast"></a>-brightness-contrast <var>brightness</var><br />-brightness-contrast <var>brightness</var>{x<var>contrast</var>}{<var>%</var>}</h3>
725</div>
726
727<p class="magick-description">Adjust the brightness and/or contrast of the image.</p>
728
729<p>Brightness and Contrast values apply changes to the input image. They are
730not absolute settings. A brightness or contrast value of zero means no change.
731The range of values is -100 to +100 on each. Positive values increase the
732brightness or contrast and negative values decrease the brightness or contrast.
733To control only contrast, set the brightness=0. To control only brightness,
734set contrast=0 or just leave it off.</p>
735
736<p>You may also use <a href="command-line-options.html#fill">-channel</a> to control which channels to
737apply the brightness and/or contrast change. The default is to apply the same
738transformation to all channels.</p>
739
740<p>Brightness and Contrast arguments are converted to offset and slope of a
741linear transform and applied
742using <a href="command-line-options.html#fill">-function polynomial "slope,offset"</a>.</p>
743
744<p>The slope varies from 0 at contrast=-100 to almost vertical at
745contrast=+100. For brightness=0 and contrast=-100, the result are totally
746midgray. For brightness=0 and contrast=+100, the result will approach but
747not quite reach a threshold at midgray; that is the linear transformation
748is a very steep vertical line at mid gray.</p>
749
750<p>Negative slopes, i.e. negating the image, are not possible with this
751function. All achievable slopes are zero or positive.</p>
752
753<p>The offset varies from -0.5 at brightness=-100 to 0 at brightness=0 to +0.5
754at brightness=+100. Thus, when contrast=0 and brightness=100, the result is
755totally white. Similarly, when contrast=0 and brightness=-100, the result is
756totally black.</p>
757
758<p>As the range of values for the arguments are -100 to +100, adding the '%'
759symbol is no different than leaving it off.</p>
760
761<div style="margin: auto;">
762  <h3><a class="anchor" id="cache"></a>-cache <var>threshold</var></h3>
763</div>
764
765<p class="magick-description">(This option has been replaced by the <a href='command-line-options.html#limit'>-limit</a> option).</p>
766
767<div style="margin: auto;">
768  <h3><a class="anchor" id="canny"></a>-canny <var>radius</var><br/>-canny <var>radius</var>x<var>sigma</var>{<var>+lower-percent</var>}{<var>+upper-percent</var>}</h3>
769</div>
770
771<p class="magick-description">Canny edge detector uses a multi-stage algorithm to detect a wide range of edges in the image.</p>
772
773<p>The thresholds range from 0 to 100% (e.g. -canny 0x1+10%+30%) with {<var>+lower-percent</var>} &lt; {<var>+upper-percent</var>}. If {<var>+upper-percent</var>} is increased but {<var>+lower-percent</var>} remains the same, lesser edge components will be detected, but their lengths will be the same. If {<var>+lower-percent</var>} is increased but {<var>+upper-percent</var>} is the same, the same number of edge components will be detected but their lengths will be shorter. The default thresholds are shown. The <var>radius</var>x<var>sigma</var> controls a gaussian blur applied to the input image to reduce noise and smooth the edges.</p>
774
775<div style="margin: auto;">
776  <h3><a class="anchor" id="caption"></a>-caption <var>string</var></h3>
777</div>
778
779<p class="magick-description">Assign a caption to an image.</p>
780
781<p>This option sets the caption meta-data of an image read in after this
782option has been given.  To modify a caption of images already in memory use
783"<code><a href="command-line-options.html#set">-set</a> caption</code>". </p>
784
785<p>The caption can contain special format characters listed in the <a
786href="../www/escape.html">Format and
787Print Image Properties</a>. These attributes are expanded when the caption
788is finally assigned to the individual images. </p>
789
790<p>If the first character of <var>string</var> is <var>@</var>, the image caption is read from a file titled by the
791remaining characters in the string.  Comments read in from a file are literal;
792no embedded formatting characters are recognized.</p>
793
794<p>Caption meta-data is not visible on the image itself. To do that use the
795<a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
796instead.</p>
797
798<p>For example,</p>
799
800<pre class="highlight"><code>-caption "%m:%f %wx%h"  bird.miff
801</code></pre>
802
803<p>produces an image caption of <code>MIFF:bird.miff 512x480</code> (assuming
804that the image <code>bird.miff</code> has a width of 512 and a height of
805480.</p>
806
807
808<div style="margin: auto;">
809  <h3><a class="anchor" id="cdl"></a>-cdl <var>filename</var></h3>
810</div>
811
812<p class="magick-description">color correct with a color decision list.</p>
813
814<p>Here is an example color correction collection:</p>
815
816<pre class="highlight"><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
817&lt;ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2"&gt;
818  &lt;ColorCorrection id="cc06668"&gt;
819    &lt;SOPNode&gt;
820      &lt;Slope&gt; 0.9 1.2 0.5 &lt;/Slope&gt;
821      &lt;Offset&gt; 0.4 -0.5 0.6 &lt;/Offset&gt;
822      &lt;Power&gt; 1.0 0.8 1.5 &lt;/Power&gt;
823    &lt;/SOPNode&gt;
824    &lt;SATNode&gt;
825      &lt;Saturation&gt; 0.85 &lt;/Saturation&gt;
826    &lt;/SATNode&gt;
827  &lt;/ColorCorrection&gt;
828&lt;/ColorCorrectionCollection&gt;
829</code></pre>
830
831<div style="margin: auto;">
832  <h3><a class="anchor" id="channel"></a>-channel <var>type</var></h3>
833</div>
834
835<p class="magick-description">Specify those image color channels to which subsequent operators are limited.</p>
836
837<p>Choose from: <code>Red</code>, <code>Green</code>, <code>Blue</code>,
838<code>Alpha</code>, <code>Gray</code>, <code>Cyan</code>, <code>Magenta</code>,
839<code>Yellow</code>, <code>Black</code>, <code>Opacity</code>,
840<code>Index</code>, <code>RGB</code>, <code>RGBA</code>, <code>CMYK</code>, or
841<code>CMYKA</code>.</p>
842
843<p>The channels above can also be specified as a comma-separated list or can be
844abbreviated as a concatenation of the letters '<code>R</code>', '<code>G</code>',
845'<code>B</code>', '<code>A</code>', '<code>O</code>', '<code>C</code>',
846'<code>M</code>', '<code>Y</code>', '<code>K</code>'.</p>
847
848<p>The numerals 0 to 31 may also be used to specify channels, where 0 to 5 are: <br />
849'<code>0</code>' equals <code>Red</code> or <code>Cyan</code> <br />
850'<code>1</code>' equals <code>Green</code> or <code>Magenta</code> <br />
851'<code>2</code>' equals <code>Blue</code> or <code>Yellow</code> <br />
852'<code>3</code>' equals <code>Black</code> <br />
853'<code>4</code>' equals <code>Alpha</code> or <code>Opacity</code> <br />
854'<code>5</code>' equals <code>Index</code></p>
855
856<p>For example, to only select the <code>Red</code> and <code>Blue</code> channels
857you can use any of the following:</p>
858<pre class="highlight">
859<code>-channel Red,Blue</code>
860<code>-channel R,B</code>
861<code>-channel RB</code>
862<code>-channel 0,2</code>
863</pre>
864
865<p>All the channels that are present in an image can be specified using the
866special channel type <code>All</code>. Not all operators are 'channel capable',
867but generally any operators that are generally 'grey-scale' image operators,
868will understand this setting.  See individual operator documentation. </p>
869
870<br/>
871
872<p>On top of the normal channel selection an extra flag can be specified,
873'<code>Sync</code>'.  This is turned on by default and if set means that
874operators that understand this flag should perform: cross-channel
875synchronization of the channels. If not specified, then most grey-scale
876operators will apply their image processing operations to each individual
877channel (as specified by the rest of the <a href="command-line-options.html#channel">-channel</a>
878setting) completely independently from each other. </p>
879
880<p>For example for operators such as <a href="command-line-options.html#auto-level">-auto-level</a> and
881<a href="command-line-options.html#auto-gamma">-auto-gamma</a> the color channels are modified
882together in exactly the same way so that colors will remain in-sync. Without
883it being set, then each channel is modified separately and
884independently, which may produce color distortion. </p>
885
886<p>The <a href="command-line-options.html#morphology">-morphology</a> '<code>Convolve</code>' method
887and the <a href="command-line-options.html#compose">-compose</a> mathematical methods, also understands
888the '<code>Sync</code>' flag to modify the behavior of pixel colors according
889to the alpha channel (if present). That is to say it will modify the image
890processing with the understanding that fully-transparent colors should not
891contribute to the final result. </p>
892
893<p>Basically, by default, operators work with color channels in synchronous, and
894treats transparency as special, unless the <a href="command-line-options.html#channel">-channel</a>
895setting is modified so as to remove the effect of the '<code>Sync</code>' flag.
896How each operator does this depends on that operators current implementation.
897Not all operators understands this flag at this time, but that is changing.
898</p>
899
900<p>To print a complete list of channel types, use <a href="command-line-options.html#list">-list
901channel</a>.</p>
902
903<p>By default, ImageMagick sets <a href="command-line-options.html#channel">-channel</a> to the value
904'<code>RGBK,sync</code>', which specifies that operators act on all color
905channels except the transparency channel, and that all the color channels are
906to be modified in exactly the same way, with an understanding of transparency
907(depending on the operation being applied).  The 'plus' form <a
908href="command-line-options.html#channel" >+channel</a> will reset the value back to this default. </p>
909
910<p>Options that are affected by the <a href="command-line-options.html#channel" >-channel</a> setting
911include the following.
912
913<a href="command-line-options.html#auto-gamma">-auto-gamma</a>,
914<a href="command-line-options.html#auto-level">-auto-level</a>,
915<a href="command-line-options.html#black-threshold">-black-threshold</a>,
916<a href="command-line-options.html#blur">-blur</a>,
917<a href="command-line-options.html#clamp">-clamp</a>,
918<a href="command-line-options.html#clut">-clut</a>,
919<a href="command-line-options.html#combine">-combine</a>,
920<a href="command-line-options.html#composite">-composite</a> (Mathematical compose methods only),
921<a href="command-line-options.html#convolve">-convolve</a>,
922<a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>,
923<a href="command-line-options.html#evaluate">-evaluate</a>,
924<a href="command-line-options.html#function">-function</a>,
925<a href="command-line-options.html#fx">-fx</a>,
926<a href="command-line-options.html#gaussian-blur">-gaussian-blur</a>,
927<a href="command-line-options.html#hald-clut">-hald-clut</a>,
928<a href="command-line-options.html#motion-blur">-motion-blur</a>,
929<a href="command-line-options.html#morphology">-morphology</a>,
930<a href="command-line-options.html#negate">-negate</a>,
931<a href="command-line-options.html#normalize">-normalize</a>,
932<a href="command-line-options.html#ordered-dither">-ordered-dither</a>,
933<a href="command-line-options.html#radial-blur">-radial-blur</a>,
934<a href="command-line-options.html#random-threshold">-random-threshold</a>,
935<a href="command-line-options.html#range-threshold">-range-threshold</a>,
936<a href="command-line-options.html#separate">-separate</a>,
937<a href="command-line-options.html#threshold">-threshold</a>, and
938<a href="command-line-options.html#white-threshold">-white-threshold</a>.
939</p>
940
941<p>Warning, some operators behave differently when the <a href="command-line-options.html#channel"
942>+channel</a> default setting is in effect, verses ANY user defined <a
943href="command-line-options.html#channel" >-channel</a> setting (including the equivalent of the
944default). These operators have yet to be made to understand the newer 'Sync'
945flag. </p>
946
947<p>For example <a href="command-line-options.html#threshold">-threshold</a> will by default grayscale
948the image before thresholding, if no <a href="command-line-options.html#channel" >-channel</a> setting
949has been defined. This is not 'Sync flag controlled, yet. </p>
950
951<p>Also some operators such as <a href="command-line-options.html#blur">-blur</a>, <a
952href="command-line-options.html#gaussian-blur">-gaussian-blur</a>, will modify their handling of the
953color channels if the '<code>alpha</code>' channel is also enabled by <a
954href="command-line-options.html#channel" >-channel</a>.  Generally this done to ensure that
955fully-transparent colors are treated as being fully-transparent, and thus any
956underlying 'hidden' color has no effect on the final results.  Typically
957resulting in 'halo' effects. The newer <a href="command-line-options.html#morphology">-morphology</a>
958convolution equivalents however does have a understanding of the 'Sync' flag
959and will thus handle transparency correctly by default. </p>
960
961<p>As a alpha channel is optional within images, some operators will read the
962color channels of an image as a greyscale alpha mask, when the image has no
963alpha channel present, and the <a href="command-line-options.html#channel" >-channel</a> setting tells
964the operator to apply the operation using alpha channels. The <a
965href="command-line-options.html#clut">-clut</a> operator is a good example of this. </p>
966
967<div style="margin: auto;">
968  <h3><a class="anchor" id="channel-fx"></a>-channel-fx <var>expression</var></h3>
969</div>
970
971<p class="magick-description">exchange, extract, or copy one or more image channels.</p>
972
973<p>The expression consists of one or more channels, either mnemonic or numeric (e.g. red or 0, green or 1, etc.), separated by certain operation symbols as follows:</p>
974
975<pre class="highlight"><code>&lt;=&gt;  exchange two channels (e.g. red&lt;=&gt;blue)
976=&gt;   copy one channel to another channel (e.g. red=&gt;green)
977=    assign a constant value to a channel (e.g. red=50%)
978,    write new image with channels in the specified order (e.g. red, green)
979;    add a new output image for the next set of channel operations (e.g. red; green; blue)
980|    move to the next input image for the source of channel data (e.g. | gray=>alpha)
981</code></pre>
982
983<p>For example, to create 3 grayscale images from the red, green, and blue channels of an image, use:</p>
984
985<pre class="highlight"><code>-channel-fx "red; green; blue"
986</code></pre>
987
988<p>A channel without an operation symbol implies separate (i.e, semicolon).</p>
989
990<p>Here we take an sRGB image and a grayscale image and inject the grayscale image into the alpha channel:</p>
991<pre class="highlight"><code>convert wizard.png mask.pgm -channel-fx '| gray=>alpha' wizard-alpha.png
992</code></pre>
993<p>Use a similar command to define a read mask:</p>
994<pre class="highlight"><code>convert wizard.png mask.pgm -channel-fx '| gray=>read-mask' wizard-mask.png
995</code></pre>
996
997<p>Add <code>-debug pixel</code> prior to the <code>-channel-fx</code> option to track the channel morphology.</p>
998
999<div style="margin: auto;">
1000  <h3><a class="anchor" id="charcoal"></a>-charcoal <var>factor</var></h3>
1001</div>
1002
1003<p class="magick-description">Simulate a charcoal drawing.</p>
1004
1005<div style="margin: auto;">
1006  <h3><a class="anchor" id="chop"></a>-chop <var>geometry</var></h3>
1007</div>
1008
1009<p class="magick-description">Remove pixels from the interior of an image.</p>
1010
1011<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <var>width</var>
1012and <var>height</var> given in the of the <var>size</var>
1013portion of the <var>geometry</var> argument give the number of
1014columns and rows to remove. The <var>offset</var> portion of
1015the <var>geometry</var> argument is influenced by
1016a <a href="command-line-options.html#gravity">-gravity</a> setting, if present.</p>
1017
1018<p>The <a href="command-line-options.html#chop">-chop</a> option removes entire rows and columns,
1019and moves the remaining corner blocks leftward and upward to close the gaps.</p>
1020
1021<p>While it can remove internal rows and columns of pixels, it is more
1022typically used with as <a href="command-line-options.html#gravity">-gravity</a> setting and zero
1023offsets so as to remove a single edge from an image.  Compare this to <a
1024href="command-line-options.html#shave" >-shave</a> which removes equal numbers of pixels from opposite
1025sides of the image.  </p>
1026
1027<p>Using <a href="command-line-options.html#chop">-chop</a> effectively undoes the results of a <a
1028href="command-line-options.html#splice">-splice</a> that was given the same <var>geometry</var> and <a href="command-line-options.html#gravity">-gravity</a> settings. </p>
1029
1030<div style="margin: auto;">
1031  <h3><a class="anchor" id="clahe"></a>-clahe <var>width</var>x<var>height</var>{%}{+}<var>number-bins</var>{+}<var>clip-limit</var>{!}</h3>
1032</div>
1033
1034<p class="magick-description">contrast limited adaptive histogram equalization. The image is divided into tiles of <var>width</var> and <var>height</var> pixels.  The tile size should be larger than the size of features to be preserved and respects the aspect ratio of the image.  Add <code>!</code> to force an exact tile width and height. <var>number-bins</var> is the number of histogram bins per tile (min 2, max 65536).  The number of histogram bins should be smaller than the number of pixels in a single tile. <var>clip-limit</var> is the contrast limit for localised changes in contrast. A clip-limit of 2 to 3 is a good starting place (e.g. -clahe 50x50%+128+3).  Very large values will let the histogram equalization do whatever it wants to do, that is result in maximal local contrast. The value 1 will result in the original image.  Note if number of bins and the clip-limit are ommitted, they default to 128 and no clipping respectively.</p>
1035
1036
1037<div style="margin: auto;">
1038  <h3><a class="anchor" id="clamp"></a>-clamp</h3>
1039</div>
1040
1041<p class="magick-description">set each pixel whose value is below zero to zero and any the pixel whose value is above the quantum range to the quantum range (e.g. 65535) otherwise the pixel value remains unchanged.</p>
1042
1043<div style="margin: auto;">
1044  <h3><a class="anchor" id="clip"></a>-clip</h3>
1045</div>
1046
1047<p class="magick-description">Apply the clipping path if one is present.</p>
1048
1049<p>If a clipping path is present, it is applied to subsequent operations.</p>
1050
1051<p>For example, in the command</p>
1052
1053<pre class="highlight"><code>convert cockatoo.tif -clip -negate negated.tif
1054</code></pre>
1055
1056<p>only the pixels within the clipping path are negated.</p>
1057
1058<p>The <a href="command-line-options.html#clip">-clip</a> feature requires SVG support. If the SVG
1059delegate library is not present, the option is ignored.</p>
1060
1061<p>Use <a href="command-line-options.html#clip">+clip</a> to disable clipping for subsequent operations.</p>
1062
1063<div style="margin: auto;">
1064  <h3><a class="anchor" id="clip-mask"></a>-clip-mask</h3>
1065</div>
1066
1067<p class="magick-description">Clip the image as defined by this mask.</p>
1068
1069<p>Use the alpha channel of the current image as a mask.  Any areas that is
1070white is not modified by any of the 'image processing operators' that follow,
1071until the mask is removed. Pixels in the black areas of the clip mask are
1072modified per the requirements of the operator. </p>
1073
1074<p>In some ways this is similar to (though not the same) as defining
1075a rectangular <a href="command-line-options.html#region" >-region</a>, or using the negative of the
1076mask (third) image in a three image <a href="command-line-options.html#composite" >-composite</a>,
1077operation. </p>
1078
1079<p>Use <a href="command-line-options.html#clip-mask">+clip-mask</a> to disable clipping for subsequent operations.</p>
1080
1081<div style="margin: auto;">
1082  <h3><a class="anchor" id="clip-path"></a>-clip-path <var>id</var></h3>
1083</div>
1084
1085<p class="magick-description">Clip along a named path from the 8BIM profile.</p>
1086
1087<p>This is identical to <a href="command-line-options.html#clip">-clip</a> except choose a specific clip path in the event the image has more than one path available. </p>
1088
1089<p>Use <a href="command-line-options.html#clip-path">+clip-path</a> to disable clipping for subsequent operations.</p>
1090
1091<div style="margin: auto;">
1092  <h3><a class="anchor" id="clone"></a>-clone <var>index(s)</var></h3>
1093</div>
1094
1095<p class="magick-description">make a clone of an image (or images).</p>
1096
1097<p>Inside parenthesis (where the operator is normally used) it will make a
1098clone of the images from the last 'pushed' image sequence, and adds them to
1099the end of the current image sequence. Outside parenthesis
1100(not recommended) it clones the images from the current image sequence. </p>
1101
1102<p>Specify the image by its index in the sequence.  The first image is index
11030.  Negative indexes are relative to the end of the sequence; for
1104example, <code>−1</code>
1105represents the last image of the sequence.  Specify a range of images with a
1106dash (e.g. <code>0−4</code>).  Separate multiple indexes with commas but no
1107spaces (e.g. <code>0,2,5</code>).  A value of '<code>0−−1</code> will
1108effectively clone all the images. </p>
1109
1110<p>The <a href="command-line-options.html#clone">+clone</a> will simply make a copy of the last image
1111in the image sequence, and is thus equivalent to using a argument of
1112'<code>−1</code>'. </p>
1113
1114<div style="margin: auto;">
1115  <h3><a class="anchor" id="clut"></a>-clut</h3>
1116</div>
1117
1118<p class="magick-description">Replace the channel values in the first image using each corresponding channel in the second image as a <b>c</b>olor <b>l</b>ook<b>u</b>p <b>t</b>able.</p>
1119
1120<p>The second (LUT) image is ordinarily a gradient image containing the
1121histogram mapping of how each channel should be modified. Typically it is a
1122either a single row or column image of replacement color values. If larger
1123than a single row or column, values are taken from a diagonal line from
1124top-left to bottom-right corners.</p>
1125
1126<p>The lookup is further controlled by the <a
1127href="command-line-options.html#interpolate">-interpolate</a> setting, which is especially handy for an
1128LUT which is not the full length needed by the ImageMagick installed Quality
1129(Q) level. Good settings for this are the '<code>bilinear</code>' and
1130'<code>bicubic</code>' interpolation settings, which give smooth color
1131gradients, and the '<code>integer</code>' setting for a direct, unsmoothed
1132lookup of color values. </p>
1133
1134<p>This operator is especially suited to replacing a grayscale image with a
1135specific color gradient from the CLUT image. </p>
1136
1137<p>Only the channel values defined by the <a href="command-line-options.html#channel">-channel</a>
1138setting will have their values replaced. In particular, since the default <a
1139href="command-line-options.html#channel">-channel</a> setting is <code>RGB</code>, this means that
1140transparency (alpha/matte channel) is not affected, unless the <a
1141href="command-line-options.html#channel">-channel</a> setting is modified. When the alpha channel is
1142set, it is treated by the <a href="command-line-options.html#clut" >-clut</a> operator in the same way
1143as the other channels, implying that alpha/matte values are replaced using the
1144alpha/matte values of the original image. </p>
1145
1146<p>If either the image being modified, or the lookup image, contains no
1147transparency (i.e. <a href="command-line-options.html#alpha" >-alpha</a> is turned 'off') but the <a
1148href="command-line-options.html#channel">-channel</a> setting includes alpha replacement, then it is
1149assumed that image represents a grayscale gradient which is used for the
1150replacement alpha values.  That is you can use a grayscale CLUT image to
1151adjust a existing images alpha channel, or you can color a grayscale image
1152using colors form CLUT containing the desired colors, including transparency.
1153</p>
1154
1155<p>See also <a href="command-line-options.html#hald-clut" >-hald-clut</a> which replaces colors
1156according to the lookup of the full color RGB value from a 2D representation
1157of a 3D color cube. </p>
1158
1159
1160<div style="margin: auto;">
1161  <h3><a class="anchor" id="coalesce"></a>-coalesce</h3>
1162</div>
1163
1164<p class="magick-description">Fully define the look of each frame of an GIF animation sequence, to form a 'film strip' animation.</p>
1165
1166<p>Overlay each image in an image sequence according to
1167its <a href="command-line-options.html#dispose">-dispose</a> meta-data, to reproduce the look of
1168an animation at each point in the animation sequence. All images should be
1169the same size, and are assigned appropriate GIF disposal settings for the
1170animation to continue working as expected as a GIF animation.  Such frames
1171are more easily viewed and processed than the highly optimized GIF overlay
1172images.  </p>
1173
1174<p>The animation can be re-optimized after processing using
1175the <a href="command-line-options.html#layers">-layers</a> method '<code>optimize</code>', although
1176there is no guarantee that the restored GIF animation optimization is
1177better than the original. </p>
1178
1179
1180<div style="margin: auto;">
1181  <h3><a class="anchor" id="colorize"></a>-colorize <var>value</var></h3>
1182</div>
1183
1184<p class="magick-description">Colorize the image by an amount specified by <var>value</var> using the color specified by the most recent <a href="command-line-options.html#fill" >-fill</a> setting.</p>
1185
1186<p>Specify the amount of colorization as a percentage. Separate colorization
1187values can be applied to the red, green, and blue channels of the image with
1188a comma-delimited list of colorization
1189values (e.g., <code>-colorize 0,0,50</code>).</p>
1190
1191<div style="margin: auto;">
1192  <h3><a class="anchor" id="colormap"></a>-colormap <var>type</var></h3>
1193</div>
1194
1195<p class="magick-description">Define the colormap type.</p>
1196
1197<p>The <var>type</var> can be  <code>shared</code> or <code>private</code>.</p>
1198
1199<p>This option only applies when the default X server visual
1200is <code>PseudoColor</code> or <code>GrayScale</code>. Refer
1201to <a href="command-line-options.html#visual">-visual</a> for more details. By default,
1202a shared colormap is allocated. The image shares colors with
1203other X clients. Some image colors could be approximated,
1204therefore your image may look very different than intended.
1205If <code>private</code> is chosen, the image colors appear exactly
1206as they are defined. However, other clients may go <var>technicolor</var>
1207when the image colormap is installed.</p>
1208
1209<div style="margin: auto;">
1210  <h3><a class="anchor" id="colors"></a>-colors <var>value</var></h3>
1211</div>
1212
1213<p class="magick-description">Set the preferred number of colors in the image.</p>
1214
1215<p>The actual number of colors in the image may be less than your request,
1216but never more. Note that this a color reduction option. Images with fewer
1217unique colors than specified by <var>value</var> will have any
1218duplicate or unused colors removed.  The ordering of an existing color
1219palette may be altered. When converting an image from color to grayscale,
1220it is more efficient to convert the image to the gray colorspace before
1221reducing the number of colors. Refer to
1222the <a href="../www/quantize.html">
1223color reduction algorithm</a> for more details.</p>
1224
1225<div style="margin: auto;">
1226  <h3><a class="anchor" id="color-matrix"></a>-color-matrix <var>matrix</var></h3>
1227</div>
1228
1229<p class="magick-description">apply color correction to the image.</p>
1230
1231<p>This option permits saturation changes, hue rotation, luminance to alpha,
1232and various other effects.  Although variable-sized transformation matrices
1233can be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6
1234for CMYKA (or RGBA with offsets).  The matrix is similar to those used by
1235Adobe Flash except offsets are in column 6 rather than 5 (in support of
1236CMYKA images) and offsets are normalized (divide Flash offset by 255).</p>
1237
1238<p>As an example, to add contrast to an image with offsets, try this command:</p>
1239
1240<pre class="highlight"><code>convert kittens.jpg -color-matrix \
1241  " 1.5 0.0 0.0 0.0, 0.0, -0.157 \
1242    0.0 1.5 0.0 0.0, 0.0, -0.157 \
1243    0.0 0.0 1.5 0.0, 0.0, -0.157 \
1244    0.0 0.0 0.0 1.0, 0.0,  0.0 \
1245    0.0 0.0 0.0 0.0, 1.0,  0.0 \
1246    0.0 0.0 0.0 0.0, 0.0,  1.0" kittens.png
1247</code></pre>
1248<div style="margin: auto;">
1249  <h3><a class="anchor" id="colorspace"></a>-colorspace <var>value</var></h3>
1250</div>
1251
1252<p class="magick-description">Set the image colorspace.</p>
1253
1254<p>Choices are:</p>
1255
1256<pre class="highlight"><code>CMY          CMYK         Gray         HCL
1257HCLp         HSB          HSI          HSL
1258HSV          HWB          Lab          LCHab
1259LCHuv        LMS          Log          Luv
1260OHTA         Rec601YCbCr  Rec709YCbCr  RGB
1261scRGB        sRGB         Transparent  xyY
1262XYZ          YCbCr        YCC          YDbDr
1263YIQ          YPbPr        YUV          Undefined
1264</code></pre>
1265
1266<p>To print a complete list of colorspaces, use <a href="command-line-options.html#list">-list colorspace</a>.</p>
1267
1268<p>For a more accurate color conversion to or from the linear RGB, CMYK, or grayscale colorspaces, use the <a href="command-line-options.html#profile">-profile</a> option.  Note, ImageMagick assumes the sRGB colorspace if the image format does not indicate otherwise.  For colorspace conversion, the gamma function is first removed to produce linear RGB.</p>
1269
1270<table class="table table-sm table-striped">
1271        <caption>Conversion of RGB to Other Color Spaces</caption>
1272        <tr><th valign="middle">CMY</th></tr>
1273        <tr><td valign="middle">C=<var>QuantumRange</var>−R</td></tr>
1274        <tr><td valign="middle">M=<var>QuantumRange</var>−G</td></tr>
1275        <tr><td valign="middle">Y=<var>QuantumRange</var>−B</td></tr>
1276        <tr><th valign="middle">CMYK — starts with CMY from above</th></tr>
1277        <tr><td valign="middle">K=min(C,Y,M)</td></tr>
1278        <tr><td valign="middle">C=<var>QuantumRange</var>*(C−K)/(<var>QuantumRange</var>−K)</td></tr>
1279        <tr><td valign="middle">M=<var>QuantumRange</var>*(M−K)/(<var>QuantumRange</var>−K)</td></tr>
1280        <tr><td valign="middle">Y=<var>QuantumRange</var>*(Y−K)/(<var>QuantumRange</var>−K)</td></tr>
1281
1282        <tr><th valign="middle">Gray</th></tr>
1283        <tr><td valign="middle">Gray = 0.212656*R+0.715158*G+0.072186*B</td></tr>
1284
1285        <tr><th valign="middle">HSB — Hue, Saturation, Brightness; like a cone peak downward</th></tr>
1286        <tr><td valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1287        <tr><td valign="middle">S=distance from axis outward</td></tr>
1288        <tr><td valign="middle">B=distance along axis from bottom upward; B=max(R,G,B); <var>intensity-like</var></td></tr>
1289
1290        <tr><th valign="middle">HSL — Hue, Saturation, Lightness; like a double cone end-to-end with peaks at very top and bottom</th></tr>
1291        <tr><td valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1292        <tr><td valign="middle">S=distance from axis outward</td></tr>
1293        <tr><td valign="middle">L=distance along axis from bottom upward; L=0.5*max(R,G,B) + 0.5*min(R,G,B); <var>intensity-like</var></td></tr>
1294
1295        <tr><th valign="middle">HWB — Hue, Whiteness, Blackness</th></tr>
1296        <tr><td valign="middle">Hue (complicated equation)</td></tr>
1297        <tr><td valign="middle">Whiteness (complicated equation)</td></tr>
1298        <tr><td valign="middle">Blackness (complicated equation)</td></tr>
1299
1300        <tr><th valign="middle">LAB</th></tr>
1301        <tr><td valign="middle">L (complicated equation relating X,Y,Z)</td></tr>
1302        <tr><td valign="middle">A (complicated equation relating X,Y,Z)</td></tr>
1303        <tr><td valign="middle">B (complicated equation relating X,Y,Z)</td></tr>
1304        <tr><th valign="middle">LinearGray</th></tr>
1305        <tr><td valign="middle">LinearGray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1306
1307        <tr><th valign="middle">LOG</th></tr>
1308        <tr><td valign="middle">I1 (complicated equation involving logarithm of R)</td></tr>
1309        <tr><td valign="middle">I2 (complicated equation involving logarithm of G)</td></tr>
1310        <tr><td valign="middle">I3 (complicated equation involving logarithm of B)</td></tr>
1311
1312        <tr><th valign="middle">OHTA — approximates principal components transformation</th></tr>
1313        <tr><td valign="middle">I1=0.33333*R+0.33334*G+0.33333*B; <var>intensity-like</var></td></tr>
1314        <tr><td valign="middle">I2=(0.50000*R+0.00000*G−0.50000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1315        <tr><td valign="middle">I3=(−0.25000*R+0.50000*G−0.25000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1316
1317        <tr><th valign="middle">Rec601Luma</th></tr>
1318        <tr><td valign="middle">Gray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1319
1320        <tr><th valign="middle">Rec601YCbCr</th></tr>
1321        <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1322        <tr><td valign="middle">Cb=(−0.168736*R-0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1323        <tr><td valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1324
1325        <tr><th valign="middle">Rec709Luma</th></tr>
1326        <tr><td valign="middle">Gray=0.212656*R+0.715158*G+0.072186*B</td></tr>
1327
1328        <tr><th valign="middle">Rec709YCbCr</th></tr>
1329        <tr><td valign="middle">Y=0.212656*R+0.715158*G+0.072186*B; <var>intensity-like</var></td></tr>
1330        <tr><td valign="middle">Cb=(−0.114572*R−0.385428*G+0.500000*B)+(<var>QuantumRange</var>+1)/2</td></tr>
1331        <tr><td valign="middle">Cr=(0.500000*R−0.454153*G−0.045847*B)+(<var>QuantumRange</var>+1)/2</td></tr>
1332        <tr><th valign="middle">sRGB</th></tr>
1333        <tr><td valign="middle">if R ≤ .0.0031308 then Rs=R/12.92 else Rs=1.055 R ^ (1.0 / 2.4) - 0.055</td></tr>
1334        <tr><td valign="middle">if G ≤ .0.0031308 then Gs=B/12.92 else Gs=1.055 R ^ (1.0 / 2.4) - 0.055</td></tr>
1335        <tr><td valign="middle">if B ≤ .0.0031308 then Bs=B/12.92 else Bs=1.055 R ^ (1.0 / 2.4) - 0.055</td></tr>
1336
1337        <tr><th valign="middle">XYZ</th></tr>
1338        <tr><td valign="middle">X=0.4124564*R+0.3575761*G+0.1804375*B</td></tr>
1339        <tr><td valign="middle">Y=0.2126729*R+0.7151522*G+0.0721750*B</td></tr>
1340        <tr><td valign="middle">Z=0.0193339*R+0.1191920*G+0.9503041*B</td></tr>
1341
1342        <tr><th valign="middle">YCC</th></tr>
1343        <tr><td valign="middle">Y=(0.298839*R+0.586811*G+0.114350*B) (with complicated scaling); <var>intensity-like</var></td></tr>
1344        <tr><td valign="middle">C1=(−0.298839*R−0.586811*G+0.88600*B) (with complicated scaling)</td></tr>
1345        <tr><td valign="middle">C2=(0.70100*R−0.586811*G−0.114350*B) (with complicated scaling)</td></tr>
1346
1347        <tr><th valign="middle">YCbCr</th></tr>
1348        <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1349        <tr><td valign="middle">Cb=(−0.168736*R−0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1350        <tr><td valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1351
1352        <tr><th valign="middle">YIQ</th></tr>
1353        <tr><td valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <var>intensity-like</var></td></tr>
1354        <tr><td valign="middle">I=(0.59600*R−0.27400*G−0.32200*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1355        <tr><td valign="middle">Q=(0.21100*R−0.52300*G+0.31200*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1356
1357        <tr><th valign="middle">YPbPr</th></tr>
1358        <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1359        <tr><td valign="middle">Pb=(−0.168736*R−0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1360        <tr><td valign="middle">Pr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1361
1362        <tr><th valign="middle">YUV</th></tr>
1363        <tr><td valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <var>intensity-like</var></td></tr>
1364        <tr><td valign="middle">U=(−0.14740*R−0.28950*G+0.43690*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1365        <tr><td valign="middle">V=(0.61500*R−0.51500*G−0.10000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1366</table>
1367
1368<p>Note the scRGB colorspace requires HDRI support otherwise it behaves just like linear RGB.</p>
1369
1370<p>Use the <code>Undefined</code> colorspace to identify multi-spectral images.</p>
1371
1372<div style="margin: auto;">
1373  <h3><a class="anchor" id="combine"></a>-combine</h3>
1374  <h3>+combine <var>colorspace</var></h3>
1375</div>
1376
1377<p class="magick-description">Combine one or more images into a single image.</p>
1378
1379<p>The channels (previously set by <a href="command-line-options.html#channel">-channel</a>) of the
1380combined image are taken from the grayscale values of each image in the
1381sequence, in order. For the default -channel setting of <code>RGB</code>, this
1382means the first image  is assigned to the <code>Red</code> channel, the second
1383to the <code>Green</code> channel, the third to the <code>Blue</code>.</p>
1384
1385<p>This option can be thought of as the inverse to <a
1386href="command-line-options.html#separate">-separate</a>, so long as the channel settings are the same.
1387Thus, in the following example, the final image should be a copy of the
1388original.  </p>
1389
1390<pre class="highlight"><code>convert original.png -channel RGB -separate sepimage.png
1391convert sepimage-0.png sepimage-1.png sepimage-2.png -channel RGB \
1392  -combine imagecopy.png
1393</code></pre>
1394
1395<div style="margin: auto;">
1396  <h3><a class="anchor" id="comment"></a>-comment <var>string</var></h3>
1397</div>
1398
1399<p class="magick-description">Embed a comment in an image.</p>
1400
1401<p>This option sets the comment meta-data of an image read in after this
1402option has been given.  To modify a comment of images already in memory use
1403"<code><a href="command-line-options.html#set">-set</a> comment</code>". </p>
1404
1405<p>The comment can contain special format characters listed in the <a
1406href="../www/escape.html">Format and
1407Print Image Properties</a>. These attributes are expanded when the comment
1408is finally assigned to the individual images. </p>
1409
1410<p>If the first character of <var>string</var> is <var>@</var>, the image comment is read from a file titled by the
1411remaining characters in the string.  Comments read in from a file are literal;
1412no embedded formatting characters are recognized.</p>
1413
1414<p>Comment meta-data are not visible on the image itself. To do that use the
1415<a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
1416instead.</p>
1417
1418<p>For example,</p>
1419
1420<pre class="highlight"><code>-comment "%m:%f %wx%h"  bird.miff
1421</code></pre>
1422
1423<p>produces an image comment of <code>MIFF:bird.miff 512x480</code> (assuming
1424that the image <code>bird.miff</code> has a width of 512 and a height of
1425480.</p>
1426
1427<div style="margin: auto;">
1428  <h3><a class="anchor" id="compare"></a>-compare</h3>
1429</div>
1430
1431<p class="magick-description">mathematically and visually annotate the difference between an image and its reconstruction</p>
1432
1433<p>This is a convert version of "<code>compare</code>" for two same sized images. The syntax is as follows, but other metrics are allowed.</p>
1434
1435<pre class="highlight"><code>convert image.png reference.png -metric RMSE -compare \ <br/> difference.png
1436</code></pre>
1437
1438<p>To get the metric value use the string format "%[distortion]".</p>
1439
1440<pre class="highlight"><code>convert image.png reference.png -metric RMSE -compare -format \
1441   "%[distortion]" info:
1442</code></pre>
1443
1444<div style="margin: auto;">
1445  <h3><a class="anchor" id="complex"></a>-complex <var>operator</var></h3>
1446</div>
1447
1448<p class="magick-description">perform complex mathematics on an image sequence</p>
1449
1450Choose from these operators:
1451
1452<pre class="highlight"><code>add
1453conjugate
1454divide
1455magnitude-phase
1456multiply
1457real-imaginary
1458subtract
1459</code></pre>
1460
1461<p>Optionally specify the <code>divide</code> operator SNR with <code><a href="command-line-options.html#define">-define</a> complex:snr=float</code>.</p>
1462
1463<div style="margin: auto;">
1464  <h3><a class="anchor" id="compose"></a>-compose <var>operator</var></h3>
1465</div>
1466
1467<p class="magick-description">Set the type of image composition.</p>
1468
1469<p>See <a href="../www/compose.html">Alpha Compositing</a> for
1470a detailed discussion of alpha compositing.</p>
1471
1472<p>This setting affects image processing operators that merge two (or more)
1473images together in some way.  This includes the operators,
1474<a href="command-line-options.html#composite">-compare</a>,
1475<a href="command-line-options.html#composite">-composite</a>,
1476<a href="command-line-options.html#layers">-layers</a> composite,
1477<a href="command-line-options.html#flatten">-flatten</a>,
1478<a href="command-line-options.html#mosaic">-mosaic</a>,
1479<a href="command-line-options.html#layers">-layers</a> merge,
1480<a href="command-line-options.html#border">-border</a>,
1481<a href="command-line-options.html#frame">-frame</a>,
1482and <a href="command-line-options.html#extent">-extent</a>. </p>
1483
1484<p>It is also one of the primary options for the "<code>composite</code>"
1485command.  </p>
1486
1487
1488<div style="margin: auto;">
1489  <h3><a class="anchor" id="composite"></a>-composite</h3>
1490</div>
1491
1492<p class="magick-description">Perform alpha composition on two images and an optional mask</p>
1493
1494<p>Take the first image 'destination' and overlay the second 'source' image
1495according to the current <a href="command-line-options.html#compose">-compose</a> setting. The location
1496of the 'source' or 'overlay' image is controlled according to <a
1497href="command-line-options.html#gravity" >-gravity</a>, and <a href="command-line-options.html#geometry" >-geometry</a>
1498settings. </p>
1499
1500<p>If a third image is given this is treated as a grayscale blending 'mask' image
1501relative to the first 'destination' image. This mask is blended with the
1502source image.  However for the '<code>displace</code>' compose method, the
1503mask is used to provide a separate Y-displacement image instead. </p>
1504
1505<p>If a <a href="command-line-options.html#compose">-compose</a> method requires extra numerical
1506arguments or flags these can be provided by setting the  <a
1507href="command-line-options.html#set">-set</a> '<code>option:compose:args</code>'
1508appropriately for the compose method. </p>
1509
1510<p>Some <a href="command-line-options.html#compose">-compose</a> methods can modify the 'destination'
1511image outside the overlay area. It is disabled by default.  You can enable this by setting the this define: <a href="command-line-options.html#define">-define</a> '<code>compose:clip-to-self=true</code>'.</p>
1512
1513<p>The SVG compositing specification requires that color and opacity values range between zero and QuantumRange inclusive.  You can permit values outside this range with this option: <a href="command-line-options.html#set">-set</a> '<code>option:compose:clamp=false</code></p>
1514
1515
1516<div style="margin: auto;">
1517  <h3><a class="anchor" id="compress"></a>-compress <var>type</var></h3>
1518</div>
1519
1520<p class="magick-description">Use pixel compression specified by <var>type</var> when writing the image.</p>
1521
1522<p>Choices are: <code>None</code>, <code>BZip</code>, <code
1523>Fax</code>, <code>Group4</code>, <code
1524>JPEG</code>,  <code>JPEG2000</code>, <code
1525>Lossless</code>, <code>LZW</code>, <code
1526>RLE</code> or <code>Zip</code>.</p>
1527
1528<p>To print a complete list of compression types, use <a href="command-line-options.html#list">-list
1529compress</a>.</p>
1530
1531<p>Specify <a href="command-line-options.html#compress">+compress</a> to store the binary image in an
1532uncompressed format. The default is the compression type of the specified
1533image file.</p>
1534
1535<p>If <code>LZW</code> compression is specified but LZW compression has not been
1536enabled, the image data is written in an uncompressed LZW format that can be
1537read by LZW decoders. This may result in larger-than-expected GIF files.</p>
1538
1539<p><code>Lossless</code> refers to lossless JPEG, which is only available if the
1540JPEG library has been patched to support it. Use of lossless JPEG is generally
1541not recommended.</p>
1542
1543<p>
1544When writing an ICO file, you may request that the images be encoded in
1545PNG format, by specifying <code>Zip</code> compression.</p>
1546
1547<p>
1548When writing a JNG file, specify <code>Zip</code> compression to request that
1549the alpha channel be encoded in PNG "IDAT" format, or <code>JPEG</code>
1550to request that it be encoded in JPG "JDAA" format.</p>
1551
1552<p>Use the <a href="command-line-options.html#quality">-quality</a> option to set the compression level
1553to be used by JPEG, PNG, MIFF, and MPEG encoders.
1554Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to set the
1555sampling factor to be used by JPEG, MPEG, and YUV encoders for down-sampling
1556the chroma channels.</p>
1557
1558<div style="margin: auto;">
1559  <h3><a class="anchor" id="connected-components"></a>-connected-components <var>connectivity</var></h3>
1560</div>
1561
1562<p class="magick-description"><a href="../www/connected-components.html">connected-components</a> labeling detects connected regions in an image, choose from 4 or 8 way connectivity.</p>
1563
1564<p>Use <code><a href="command-line-options.html#define" >-define</a> connected-components:verbose=true</code> to output statistics associated with each unique label.</p>
1565
1566<div style="margin: auto;">
1567  <h3><a class="anchor" id="contrast"></a>-contrast</h3>
1568</div>
1569
1570<p class="magick-description">Enhance or reduce the image contrast.</p>
1571
1572<p>This option enhances the intensity differences between the lighter and
1573darker elements of the image. Use <a href="command-line-options.html#contrast">-contrast</a> to enhance
1574the image or <a href="command-line-options.html#contrast">+contrast</a> to reduce the image
1575contrast.</p>
1576
1577<p>For a more pronounced effect you can repeat the option:</p>
1578
1579<pre class="highlight"><code>convert rose: -contrast -contrast rose_c2.png
1580</code></pre>
1581
1582<div style="margin: auto;">
1583  <h3><a class="anchor" id="contrast-stretch"></a>-contrast-stretch <var>black-point</var><br />-contrast-stretch <var>black-point</var>{x<var>white-point</var>}{<var>%</var>}</h3>
1584</div>
1585
1586<p class="magick-description">Increase the contrast in an image by <var>stretching</var> the range of intensity values.</p>
1587
1588<p>While performing the stretch, black-out at most <var>black-point</var> pixels and white-out at most <var>white-point</var> pixels. Or, if percent is used, black-out at most
1589<var >black-point %</var> pixels and white-out at most <var>white-point %</var> pixels.</p>
1590
1591<p>Prior to ImageMagick 6.4.7-0, <a href="command-line-options.html#contrast-stretch"
1592>-contrast-stretch</a> will black-out at most <var>black-point</var> pixels and white-out at most <var >total pixels
1593minus white-point</var> pixels. Or, if percent is used, black-out at most <var>black-point %</var> pixels and white-out at most <var>100% minus white-point %</var> pixels.</p>
1594
1595<p>Note that <code>-contrast-stretch 0</code> will modify the image such that
1596the image's min and max values are stretched to 0 and <var>QuantumRange</var>, respectively, without any loss of data due to burn-out or
1597clipping at either end. This is not the same as <a href="command-line-options.html#normalize"
1598>-normalize</a>, which is equivalent to <code>-contrast-stretch 0.15x0.05%</code> (or
1599prior to ImageMagick 6.4.7-0, <code>-contrast-stretch 2%x99%</code>).</p>
1600
1601<p>Internally operator works by creating a histogram bin, and then uses that
1602bin to modify the image. As such some colors may be merged together when they
1603originally fell into the same 'bin'. </p>
1604
1605<p>All the channels are normalized in concert by the same amount so as to
1606preserve color integrity, when the default <a href="command-line-options.html#channel" >+channel</a>
1607setting is in use.  Specifying any other <a href="command-line-options.html#channel" >-channel</a>
1608setting will normalize the RGB channels independently.</p>
1609
1610<p>See also  <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect'
1611normalization of mathematical images. </p>
1612
1613<p>This operator is under review for re-development. </p>
1614
1615
1616<div style="margin: auto;">
1617  <h3><a class="anchor" id="convolve"></a>-convolve <var>kernel</var></h3>
1618</div>
1619
1620<p class="magick-description">Convolve an image with a user-supplied convolution kernel.</p>
1621
1622<p>The <var>kernel</var> is a matrix specified as
1623a comma-separated list of integers (with no spaces), ordered left-to right,
1624starting with the top row. Presently, only odd-dimensioned kernels are
1625supported, and therefore the number of entries in the specified <var>kernel</var> must be 3<sup>2</sup>=9, 5<sup>2</sup>=25,
16267<sup>2</sup>=49, etc. </p>
1627
1628<p>Note that the <a href="command-line-options.html#convolve">&#x2011;convolve</a> operator supports the <a href="command-line-options.html#bias">&#x2011;bias</a> setting. This option shifts the convolution so that
1629positive and negative results are relative to a user-specified bias value.
1630This is important for non-HDRI compilations of ImageMagick when dealing with
1631convolutions that contain negative as well as positive values. This is
1632especially the case with convolutions involving high pass filters or edge
1633detection. Without an output bias, the negative values is clipped at zero.
1634</p>
1635
1636<p>When using an ImageMagick with the HDRI compile-time setting, <a href="command-line-options.html#bias">&#x2011;bias</a> is not needed, as ImageMagick is able to store/handle any
1637negative results without clipping to the color value range (0..QuantumRange).
1638See the discussion on HDRI implementations of ImageMagick on the page <a
1639href="high-dynamic-range.html">High
1640Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a
1641href="../Usage/basics/#hdri">Usage</a> pages or this
1642<a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
1643entry.  </p>
1644
1645
1646<div style="margin: auto;">
1647  <h3><a class="anchor" id="copy"></a>-copy <var>geometry</var> <var>offset</var></h3>
1648</div>
1649
1650<p class="magick-description">copy pixels from one area of an image to another.</p>
1651
1652<div style="margin: auto;">
1653  <h3><a class="anchor" id="crop"></a>-crop <var>geometry</var>{<var>@</var>}{<var>!</var>}</h3>
1654</div>
1655
1656<p class="magick-description">Cut out one or more rectangular regions of the image.</p>
1657
1658<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
1659
1660<p>The <var>width</var> and <var>height</var> of the <var>geometry</var> argument give the size of the image that remains
1661after cropping, and <var>x</var> and <var>y</var> in the
1662<var>offset</var> (if present) gives the location of the top left
1663corner of the cropped image with respect to the original image. To specify the
1664amount to be removed, use <a href="command-line-options.html#shave">-shave</a> instead.</p>
1665
1666<p>If the <var>x</var> and <var>y</var> offsets are
1667present, a single image is generated, consisting of the pixels from the
1668cropping region. The offsets specify the location of the upper left corner of
1669the cropping region measured downward and rightward with respect to the upper
1670left corner of the image. If the <a href="command-line-options.html#gravity">-gravity</a> option is
1671present with <code>NorthEast</code>, <code>East</code>, or <code>SouthEast</code>
1672gravity, it gives the distance leftward from the right edge of the image to
1673the right edge of the cropping region. Similarly, if the <a
1674href="command-line-options.html#gravity">-gravity</a> option is present with <code>SouthWest</code>,
1675<code>South</code>, or <code>SouthEast</code> gravity, the distance is measured
1676upward between the bottom edges.</p>
1677
1678<p>If the <var>x</var> and <var>y</var> offsets are
1679omitted, a set of tiles of the specified geometry, covering the entire input
1680image, is generated. The rightmost tiles and the bottom tiles are smaller if
1681the specified geometry extends beyond the dimensions of the input image.</p>
1682
1683<p>You can add the <var>@</var> to the geometry argument to equally divide the image into the number of tiles generated.</p>
1684
1685<p>By adding a exclamation character flag to the geometry argument, the
1686cropped images virtual canvas page size and offset is set as if the
1687geometry argument was a viewport or window. This means the canvas page size
1688is set to exactly the same size you specified, the image offset set
1689relative top left corner of the region cropped. </p>
1690
1691<p>If the cropped image 'missed' the actual image on its virtual canvas, a
1692special single pixel transparent 'missed' image is returned, and a 'crop
1693missed' warning given. </p>
1694
1695<p>It might be necessary to <a href="command-line-options.html#repage" >+repage</a> the image prior to
1696cropping the image to ensure the crop coordinate frame is relocated to the
1697upper-left corner of the visible image.
1698
1699Similarly you may want to use <a href="command-line-options.html#repage" >+repage</a> after cropping to
1700remove the page offset that will be left behind. This is especially true when
1701you are going to write to an image format such as PNG that supports an image
1702offset.</p>
1703
1704<div style="margin: auto;">
1705  <h3><a class="anchor" id="cycle"></a>-cycle <var>amount</var></h3>
1706</div>
1707
1708<p class="magick-description">displace image colormap by amount.</p>
1709
1710<p><var>Amount</var> defines the number of positions each
1711colormap entry is shifted.</p>
1712
1713
1714<div style="margin: auto;">
1715  <h3><a class="anchor" id="debug"></a>-debug <var>events</var></h3>
1716</div>
1717
1718<p class="magick-description">enable debug printout.</p>
1719
1720<p>The <code>events</code> parameter specifies which events are to be logged. It
1721can be either <code>None</code>, <code>All</code>, <code>Trace</code>, or
1722a comma-separated list consisting of one or more of the following domains:
1723<code>Accelerate</code>, <code>Annotate</code>, <code>Blob</code>, <code>Cache</code>,
1724<code>Coder</code>, <code>Configure</code>, <code>Deprecate</code>,
1725<code>Exception</code>, <code>Locale</code>, <code>Render</code>,
1726<code>Resource</code>, <code>Security</code>, <code>TemporaryFile</code>,
1727<code>Transform</code>, <code>X11</code>, or <code>User</code>. </p>
1728
1729
1730<p>For example, to log cache and blob events, use.</p>
1731
1732<pre class="highlight"><code>convert -debug "Cache,Blob" rose: rose.png
1733</code></pre>
1734
1735<p>The <code>User</code> domain is normally empty, but developers can log user
1736events in their private copy of ImageMagick.</p>
1737
1738<p>To print the complete list of debug methods, use <a href="command-line-options.html#list">-list
1739debug</a>.</p>
1740
1741<p>Use the <a href="command-line-options.html#log">-log</a> option to specify the format for debugging
1742output.</p>
1743
1744<p>Use <a href="command-line-options.html#debug">+debug</a> to turn off all logging.</p>
1745
1746<p>Debugging may also be set using the <code>MAGICK_DEBUG</code> <a href="resources.html#environment"
1747>environment variable</a>.  The allowed values for the <code>MAGICK_DEBUG</code>
1748environment variable are the same as for the <a href="command-line-options.html#debug">-debug</a>
1749option.</p>
1750
1751
1752<div style="margin: auto;">
1753  <h3><a class="anchor" id="decipher"></a>-decipher <var>filename</var></h3>
1754</div>
1755
1756<p class="magick-description">Decipher and restore pixels that were previously transformed by <a href="command-line-options.html#encipher">-encipher</a>.</p>
1757
1758<p>Get the passphrase from the file specified by <var>filename</var>.</p>
1759
1760<p>For more information, see the webpage, <a
1761href="../www/cipher.html">ImageMagick: Encipher or
1762Decipher an Image</a>.</p>
1763
1764
1765<div style="margin: auto;">
1766  <h3><a class="anchor" id="deconstruct"></a>-deconstruct</h3>
1767</div>
1768
1769<p class="magick-description">find areas that has changed between images </p>
1770
1771<p>Given a sequence of images all the same size, such as produced by <a
1772href="command-line-options.html#coalesce">-coalesce</a>, replace the second and later images, with
1773a smaller image of just the area that changed relative to the previous image.
1774</p>
1775
1776<p>The resulting sequence of images can be used to optimize an animation
1777sequence, though will not work correctly for GIF animations when parts of the
1778animation can go from opaque to transparent. </p>
1779
1780<p>This option is actually equivalent to the  <a href="command-line-options.html#layers">-layers</a>
1781method '<code>compare-any</code>'. </p>
1782
1783
1784<div style="margin: auto;">
1785  <h3><a class="anchor" id="define"></a>-define <var>key</var>{<var>=value</var>}<var>...</var></h3>
1786</div>
1787
1788<p class="magick-description">add specific global settings generally used to control coders and image processing operations.</p>
1789
1790<p>This option creates one or more definitions for coders and decoders to use
1791while reading and writing image data.  Definitions are generally used to
1792control image file format coder modules, and image processing operations,
1793beyond what is provided by normal means.  Defined settings are listed in <a
1794href="command-line-options.html#verbose" >-verbose</a> information ("<code>info:</code>" output format)
1795as "Artifacts". </p>
1796
1797<p>If <var>value</var> is missing for a definition, an empty-valued
1798definition of a flag is created with that name. This used to control on/off
1799options.  Use <a href="command-line-options.html#define">+define key</a> to remove definitions
1800previously created.  Use <a href="command-line-options.html#define">+define "*"</a> to remove all
1801existing definitions.</p>
1802
1803<p>The same 'artifact' settings can also be defined using the <a
1804href="command-line-options.html#set" >-set "option:<var>key</var>" "<var>value</var>"</a> option, which also allows the use of <a href="../www/escape.html" >Format and Print Image
1805Properties</a> in the defined value. </p>
1806
1807<p>The <var>option</var> and <var>key</var> are case-independent (they are
1808converted to lowercase for use within the decoders) while the <var>value</var>
1809is case-dependent.</p>
1810
1811<p>Such settings are global in scope, and affect all images and operations. </p>
1812
1813<p>The following definitions are just some of the artifacts that are
1814available:</p>
1815
1816<table class="table table-sm table-striped">
1817  <tr>
1818    <td>bmp3:alpha=<var>true|false</var></td>
1819    <td>include any alpha channel when writing in the BMP image format.</td>
1820  </tr>
1821
1822  <tr>
1823    <td>bmp:format=<var>value</var></td>
1824    <td> valid values are <var>bmp2</var>, <var>bmp3</var>,
1825   and <var>bmp4</var>.  This option can be useful when the
1826   method of prepending "BMP2:" to the output filename is inconvenient or
1827   is not available, such as when using the <a href="mogrify.html">mogrify</a>   utility.</td>
1828  </tr>
1829
1830  <tr>
1831    <td>bmp:subtype=<var>RGB555|RGB565|ARGB4444|ARGB1555</var></td>
1832    <td>BMP channel depth subtypes. Only support in BMP (BMP4). BMP3 and BMP2 do not
1833    contain header fields to support these options.</td>
1834  </tr>
1835
1836  <tr>
1837    <td>colorspace:auto-grayscale=<var>on|off</var></td>
1838    <td>prevent automatic conversion to grayscale inside coders that support
1839    grayscale. This should be accompanied by -type truecolor. PNG and TIF do
1840    not need this define. With PNG, just use PNG24:image. With TIF, just use
1841    -type truecolor. JPG and PSD will need this define.</td>
1842  </tr>
1843
1844  <tr>
1845    <td>complex:snr=<var>value</var></td>
1846    <td>Set the divide SNR constant<a href="command-line-options.html#complex">-complex</a>.</td>
1847  </tr>
1848
1849  <tr>
1850    <td>compose:args=<var>arguments</var></td>
1851     <td>Sets certain compose argument values when using convert ... -compose ...
1852    -composite. See <a href="compose.html"
1853    >Image Composition</a>.</td>
1854  </tr>
1855
1856  <tr>
1857    <td>compose:clip-to-self=<var>true|false</var></td>
1858    <td>Some <a href="command-line-options.html#compose" >-compose</a> methods can modify the 'destination' image outside the overlay area.  It is disabled by default.</td>
1859  </tr>
1860
1861  <tr>
1862    <td>compose:clamp=<var>on|off</var></td>
1863    <td>set each pixel whose value is below zero to zero and any the pixel
1864    whose value is above the quantum range to the quantum range (e.g. 65535)
1865    otherwise the pixel value remains unchanged.  Define supported in
1866    ImageMagick 6.9.1-3 and above.</td>
1867  </tr>
1868
1869  <tr>
1870    <td>connected-components:area-threshold=<var>value</var></td>
1871    <td>Merges any region with area smaller than <var>value</var> into its surrounding region or largest neighbor.</td>
1872  </tr>
1873
1874  <tr>
1875    <td>connected-components:keep=<var>list-of-ids</var></td>
1876    <td>Comma and/or hyphenated list of id values to keep in the output.
1877    Supported in Imagemagick 6.9.3-0.</td>
1878  </tr>
1879
1880  <tr>
1881    <td>connected-components:mean-color=<var>true</var></td>
1882    <td>Changes the output image from id values to mean color values. Supported
1883    in Imagemagick 6.9.2-8.</td>
1884  </tr>
1885
1886  <tr>
1887    <td>connected-components:remove=<var>list-of-ids</var></td>
1888    <td>Comma and/or hyphenated list of id values to remove from the output.
1889     Supported in Imagemagick 6.9.2-9.</td>
1890  </tr>
1891
1892  <tr>
1893    <td>connected-components:verbose=<var>true</var></td>
1894    <td>Lists id, bounding box, centroid, area, mean color for each region.</td>
1895  </tr>
1896
1897  <tr>
1898    <td>convolve:scale=<var>{kernel_scale}[!^] [,{origin_addition}] [%]</var></td>
1899     <td>Defines the kernel scaling. The special flag ! automatically scales to
1900    full dynamic range. The ! flag can be used in combination with a factor or
1901    percent. The factor or percent is then applied after the automatic scaling.
1902    An example is 50%!. This produces a result 50% darker than full dynamic
1903    range scaling. The ^ flag assures the kernel is 'zero-summing', for
1904    example when some values are positive and some are negative as in edge
1905    detection kernels. The origin addition adds that value to the center
1906    pixel of the kernel. This produces an effect that is like adding the image
1907    that many times to the result of the filtered image. The typical value
1908    is 1 so that the original image is added to the result of the convolution.
1909    The default is 0.</td>
1910  </tr>
1911
1912  <tr>
1913    <td>morphology:showKernel=<var>1</var></td>
1914     <td>Outputs (to 'standard error') all the information about a specified <a
1915    href="command-line-options.html#morphology" >-morphology convolve</a> kernel.</td>
1916  </tr>
1917
1918  <tr>
1919    <td>dcm:display-range=<var>reset</var></td>
1920     <td>Sets the display range to the minimum and maximum pixel values for the
1921    DCM image format.</td>
1922  </tr>
1923
1924  <tr>
1925    <td>dds:cluster-fit=<var>true|false</var></td>
1926     <td>Enables the dds cluster-fit.</td>
1927  </tr>
1928
1929  <tr>
1930    <td>dds:compression=<var>dxt1|dxt5|none</var></td>
1931     <td>Sets the dds compression.</td>
1932  </tr>
1933
1934  <tr>
1935    <td>dds:mipmaps=<var>value</var></td>
1936     <td>Sets the dds number of mipmaps.</td>
1937  </tr>
1938
1939  <tr>
1940     <td>dds:weight-by-alpha=<var>true|false</var></td>
1941     <td>Enables the dds alpha weighting.</td>
1942  </tr>
1943
1944  <tr>
1945    <td>deskew:auto-crop=<var>true</var></td>
1946    <td>auto crop the image after deskewing.</td>
1947  </tr>
1948
1949  <tr>
1950    <td>delegate:bimodal=<var>true</var></td>
1951     <td>Specifies direct conversion from Postscript to PDF.</td>
1952  </tr>
1953
1954  <tr>
1955    <td>distort:scale=<var>value</var></td>
1956    <td>Sets the output scaling factor for use with <a href="command-line-options.html#distort"
1957   >-distort</a>.</td>
1958  </tr>
1959
1960  <tr>
1961    <td>distort:viewport=<var>WxH+X+Y</var></td>
1962    <td>Sets the viewport for use with <a href="command-line-options.html#distort">-distort</a>.</td>
1963  </tr>
1964
1965  <tr>
1966    <td>dot:layout-engine=<var>value</var></td>
1967     <td>Specifies the layout engine for the DOT image format (e.g.
1968    <code>neato</code>).</td>
1969  </tr>
1970
1971  <tr>
1972    <td>exr:color-type=<var>value</var></td>
1973     <td>Specifies the color type for the EXR format: RGB, RGBA, YC, YCA, Y, YA, R, G, B, A).</td>
1974  </tr>
1975
1976  <tr>
1977    <td>filter:option=<var>value</var></td>
1978     <td>Set a filter option for use with <a href="command-line-options.html#resize">-resize</a>.
1979    See <a href="command-line-options.html#filter">-filter</a> for details.</td>
1980  </tr>
1981
1982  <tr>
1983    <td>fourier:normalize=<var>inverse</var></td>
1984    <td>Sets the location for the FFT/IFT normalization as use by
1985    <a href="command-line-options.html#fft">+-fft</a> and <a href="command-line-options.html#ift">+-ift</a>. The default is
1986    <var>forward</var>.</td>
1987  </tr>
1988
1989  <tr>
1990    <td>h:format=<var>value</var></td>
1991     <td>Set the image encoding format use when writing a C-style header.
1992         <var>format</var> can be any output format supported by ImageMagick
1993         except for <var>h</var> and <var>magick</var>.  If this
1994         option is omitted, the default is <var>GIF</var> for PseudoClass
1995         images and <var>PNM</var> for DirectClass images.
1996    </td>
1997  </tr>
1998
1999  <tr>
2000    <td>hough-lines:accumulator=true</td>
2001     <td>Returns the accumulator image in addition to the lines image.</td>
2002  </tr>
2003
2004  <tr>
2005    <td>heic:preserve-orientation</td>
2006    <td>Preserve the original EXIF orientation during HEIC decoding and rotate the pixels accordingly.
2007        By default, EXIF orientation is reset to "1" to match the actual orientation of pixels in HEIC.
2008    </td>
2009  </tr>
2010
2011  <tr>
2012    <td>icon:auto-resize</td>
2013     <td>Automatically stores multiple sizes when writing an ico image
2014    (requires a 256x256 input image).</td>
2015  </tr>
2016
2017  <tr>
2018    <td>identify:locate=<var>minimum|maximum</var></td>
2019     <td>Locates the coordinates of one or more image minimum or maximum.</td>
2020  </tr>
2021
2022  <tr>
2023    <td>identify:limit=<var>number</var></td>
2024     <td>Locates the coordinates for the number of minima or maxima specified.</td>
2025  </tr>
2026
2027  <tr>
2028    <td>jp2:layer-number=<var>value</var></td>
2029     <td>Sets the maximum number of quality layers to decode. Same for JPT, JC2,
2030    and J2K.</td>
2031  </tr>
2032
2033  <tr>
2034    <td>jp2:number-resolutions=<var>value</var></td>
2035     <td>Sets the number of resolutions to encode.Same for JPT, JC2, and
2036     J2K.</td>
2037  </tr>
2038
2039  <tr>
2040    <td>jp2:progression-order=<var>value</var></td>
2041     <td>choose from LRCP, RLCP, RPCL, PCRL or CPRL. Same for JPT, JC2, and
2042    J2K.</td>
2043  </tr>
2044
2045  <tr>
2046    <td>jp2:quality=<var>value,value...</var></td>
2047     <td>Sets the quality layer PSNR, given in dB. The order is from left to
2048    right in ascending order. The default is a single lossless quality layer.
2049    Same for JPT, JC2, and J2K.</td>
2050  </tr>
2051
2052  <tr>
2053    <td>jp2:rate=<var>value</var></td>
2054     <td>Specify the compression factor to use while writing JPEG-2000 files.
2055     The compression factor is the reciprocal of the compression ratio. The
2056     valid range is 0.0 to 1.0, with 1.0 indicating lossless compression. If
2057     defined, this value overrides the -quality setting.  A quality setting
2058     of 75 results in a rate value of 0.06641. Same for JPT, JC2, and J2K.</td>
2059  </tr>
2060
2061  <tr>
2062    <td>jp2:reduce-factor=<var>value</var></td>
2063     <td>Sets the number of highest resolution levels to be discarded.Same for
2064    JPT, JC2, and J2K.</td>
2065  </tr>
2066
2067  <tr>
2068    <td>jpeg:block-smoothing=<var>on|off</var></td>
2069    <td> </td>
2070  </tr>
2071
2072  <tr>
2073    <td>jpeg:colors=<var>value</var></td>
2074     <td>Set the desired number of colors and let the JPEG encoder do the
2075    quantizing.</td>
2076  </tr>
2077
2078  <tr>
2079    <td>jpeg:dct-method=<var>value</var></td>
2080     <td>Choose from <code>default</code>, <code>fastest</code>,
2081    <code>float</code>, <code>ifast</code>, and <code>islow</code>.</td>
2082  </tr>
2083
2084  <tr>
2085    <td>jpeg:extent=<var>value</var></td>
2086     <td>Restrict the maximum JPEG file size, for example <code>-define
2087    jpeg:extent=400KB</code>.  The JPEG encoder will search for the highest
2088    compression quality level that results in an output file that does not
2089    exceed the value. The <code>-quality</code> option also will be respected
2090    starting with version 6.9.2-5. Between 6.9.1-0 and 6.9.2-4, add -quality
2091    100 in order for the jpeg:extent to work properly. Prior to 6.9.1-0, the
2092    -quality setting was ignored.</td>
2093  </tr>
2094
2095  <tr>
2096    <td>jpeg:fancy-upsampling=<var>on|off</var></td>
2097    <td> </td>
2098  </tr>
2099
2100  <tr>
2101    <td>jpeg:optimize-coding=<var>on|off</var></td>
2102    <td> </td>
2103  </tr>
2104
2105  <tr>
2106    <td>jpeg:q-table=<var>table</var></td>
2107    <td> </td>
2108  </tr>
2109
2110  <tr>
2111    <td>jpeg:sampling-factor=<var>sampling-factor-string</var></td>
2112    <td> </td>
2113  </tr>
2114
2115  <tr>
2116    <td>jpeg:size=<var>geometry</var></td>
2117     <td>Set the size hint of a JPEG image, for
2118    example, <code>-define jpeg:size=128x128</code>.
2119    It is most useful for increasing performance and reducing the memory
2120    requirements when reducing the size of a large JPEG image.</td>
2121  </tr>
2122
2123  <tr>
2124    <td>json:features</td>
2125   <td>includes features in verbose information.</td>
2126  </tr>
2127
2128  <tr>
2129    <td>json:limit</td>
2130    <td> </td>
2131  </tr>
2132
2133  <tr>
2134    <td>json:locate</td>
2135    <td> </td>
2136  </tr>
2137
2138  <tr>
2139    <td>json:moments</td>
2140   <td>includes image moments in verbose information.</td>
2141  </tr>
2142
2143  <tr>
2144    <td>magick:format=<var>value</var></td>
2145     <td>Set the image encoding format use when writing a C-style header.
2146         This is the same as "h:format=format" described above.</td>
2147  </tr>
2148
2149  <tr>
2150    <td>mng:need-cacheoff</td>
2151   <td>turn playback caching off for streaming MNG.</td>
2152  </tr>
2153
2154  <tr>
2155    <td>morphology:compose=<var>compose-method</var></td>
2156     <td>Specifies how to merge results generated by multiple<a
2157    href="command-line-options.html#morphology" >-morphology</a> kernel. The default is none. One
2158    typical value is 'lighten' as used, for example, with the sobel edge
2159    kernels. </td>
2160  </tr>
2161
2162  <tr>
2163    <td>morphology:showKernel=<var>1</var></td>
2164     <td>Outputs (to 'standard error') all the information about a generated <a
2165    href="command-line-options.html#morphology" >-morphology</a> kernel.</td>
2166  </tr>
2167
2168  <tr>
2169    <td>pcl:fit-to-page=<var>true</var></td>
2170  </tr>
2171
2172  <tr>
2173    <td>pdf:fit-page=<var>geometry</var></td>
2174     <td> geometry specifies the scaling dimensions for resizing when the PDF is
2175    being read. The geometry is either WxH{%} or page size. No offsets are
2176    allowed. (introduced in IM 6.8.8-8)</td>
2177  </tr>
2178
2179  <tr>
2180    <td>pdf:fit-to-page=<var>true</var></td>
2181    <td> </td>
2182  </tr>
2183
2184  <tr>
2185    <td>pdf:use-cropbox=<var>true</var></td>
2186    <td> </td>
2187  </tr>
2188
2189  <tr>
2190    <td>pdf:use-trimbox=<var>true</var></td>
2191    <td> </td>
2192  </tr>
2193
2194  <tr>
2195    <td>pdf:stop-on-error=<var>true</var></td>
2196    <td> </td>
2197  </tr>
2198
2199  <tr>
2200    <td>pdf:pdf:page-direction=<var>right-to-left</var></td>
2201    <td> </td>
2202  </tr>
2203
2204  <tr>
2205    <td>phash:colorspaces=<var>colorspace,colorspace,...</var></td>
2206    <td>the perceptual hash defaults to the sRGB and HCLp colorspaces.  When
2207    using this define, you can specify up to six alternative colorspaces. (as
2208    of IM 7.0.3-8)</td>
2209  </tr>
2210
2211  <tr>
2212    <td>phash:normalize=<var>true</var></td>
2213    <td>normalizes the phash metric by dividing by the number of channels
2214    specified by <code>-define phash:colorspaces</code> when using compare
2215    -metric phash. (as of IM 7.0.3-8)</td>
2216  </tr>
2217
2218  <tr>
2219    <td>png:bit-depth=<var>value</var></td>
2220    <td> </td>
2221  </tr>
2222
2223  <tr>
2224    <td>png:color-type=<var>value</var></td>
2225     <td>desired bit-depth and color-type for PNG output.  You can force the PNG
2226    encoder to use a different bit-depth and color-type than it would have
2227    normally selected, but only if this does not cause any loss of image
2228    quality. Any attempt to reduce image quality is treated as an error and no
2229    PNG file is written.  E.g., if you have a 1-bit black-and-white image, you
2230    can use these "defines" to cause it to be written as an 8-bit grayscale,
2231    indexed, or even a 64-bit RGBA.  But if you have a 16-million color image,
2232    you cannot force it to be written as a grayscale or indexed PNG.  If you
2233    wish to do this, you must use the appropriate <a href="command-line-options.html#depth">-depth</a>,
2234    <a href="command-line-options.html#colors">-colors</a>, or <a href="command-line-options.html#type">-type</a> directives to
2235    reduce the image quality prior to using the PNG encoder. Note that in
2236    indexed PNG files, "bit-depth" refers to the number of bits per index,
2237    which can be 1, 2, 4, or 8.  In such files, the color samples always have
2238    8-bit depth.</td>
2239  </tr>
2240
2241  <tr>
2242    <td>png:compression-filter=<var>value</var></td>
2243    <td> valid values are 0 through 9. 0-4 are the corresponding PNG filters,
2244   5 means adaptive filtering except for images with a colormap, 6 means
2245   adaptive filtering for all images, 7 means MNG "loco" compression, 8 means
2246   Z_RLE strategy with adaptive filtering, and 9 means Z_RLE strategy with no
2247   filtering.</td>
2248  </tr>
2249
2250  <tr>
2251    <td>png:compression-level=<var>value</var></td>
2252    <td> valid values are 0 through 9, with 0 providing the least but fastest
2253       compression and 9 usually providing the best and always the slowest.</td>
2254  </tr>
2255
2256  <tr>
2257    <td>png:compression-strategy=<var>value</var></td>
2258    <td> valid values are 0 through 4, meaning default, filtered, huffman_only,
2259   rle, and fixed ZLIB compression strategy. If you are using an old zlib
2260   that does not support Z_RLE (before 1.2.0) or Z_FIXED (before 1.2.2.2),
2261   values 3 and 4, respectively, will use the zlib default strategy
2262   instead.</td>
2263  </tr>
2264
2265  <tr>
2266    <td>png:format=<var>value</var></td>
2267    <td> valid values are <var>png8</var>, <var>png24</var>,
2268   <var>png32</var>, <var>png48</var>,
2269   <var>png64</var>, and <var>png00</var>.
2270   This property can be useful for specifying
2271   the specific PNG format to be used, when the usual method of prepending the
2272   format name to the output filename is inconvenient, such as when writing
2273   a PNG-encoded ICO file or when using <a href="mogrify.html">mogrify</a>.
2274   Value = <var>png8</var> reduces the number of colors to 256,
2275   only one of which may be fully transparent, if necessary.  The other
2276   values do not force any reduction of quality; it is an error to request
2277   a format that cannot represent the image data without loss (except that
2278   it is allowed to reduce the bit-depth from 16 to 8 for all formats).
2279   Value = <var>png24</var> and <var>png48</var>
2280   allow transparency, only if a single color is fully transparent and that
2281   color does not also appear in an opaque pixel; such transparency is
2282   written in a PNG <code>tRNS</code> chunk.
2283   Value = <var>png00</var> causes the image to inherit its
2284   color-type and bit-depth from the input image, if the input was also
2285   a PNG.</td>
2286  </tr>
2287
2288  <tr>
2289    <td>png:exclude-chunk=<var>value</var></td>
2290
2291  <tr>
2292    <td>png:include-chunk=<var>value</var></td>
2293     <td>ancillary chunks to be excluded from or included in PNG output.
2294
2295    <p>The <var>value</var> can be the name of a PNG chunk-type such
2296    as <var>bKGD</var>, a comma-separated list of chunk-names
2297    (which can include the word <var>date</var>, the word
2298    <var>all</var>, or the word <var>none</var>).
2299    Although PNG chunk-names are case-dependent, you can use all lowercase
2300    names if you prefer.</p>
2301
2302    <p>The "include-chunk" and "exclude-chunk" lists only affect the behavior
2303    of the PNG encoder and have no effect on the PNG decoder.</p>
2304
2305    <p>As a special case, if the <code>sRGB</code> chunk is excluded and
2306    the <code>gAMA</code> chunk is included, the <code>gAMA</code> chunk will
2307    only be written if gamma is not 1/2.2, since most decoders assume
2308    sRGB and gamma=1/2.2 when no colorspace information is included in
2309    the PNG file.  Because the list is processed from left to right, you
2310    can achieve this with a single define:</p>
2311
2312<pre class="highlight"><code>-define png:include-chunk=none,gAMA
2313</code></pre>
2314
2315    <p>As a special case, if the <code>sRGB</code> chunk is not excluded and
2316    the PNG encoder recognizes that the image contains the sRGB ICC profile,
2317    the PNG encoder will write the <code>sRGB</code> chunk instead of the
2318    entire ICC profile.  To force the PNG encoder to write the sRGB
2319    profile as an <code>iCCP</code> chunk in the output PNG instead of the
2320    <code>sRGB</code> chunk, exclude the <code>sRGB</code> chunk.</p>
2321
2322    <p>The critical PNG chunks <code>IHDR</code>, <code>PLTE</code>,
2323    <code>IDAT</code>, and <code>IEND</code> cannot be excluded.  Any such
2324    entries appearing in the list will be ignored.</p>
2325
2326    <p>If the ancillary PNG <code>tRNS</code> chunk is excluded and the
2327    image has transparency, the PNG colortype is forced to be 4 or 6
2328    (GRAY_ALPHA or RGBA).  If the image is not transparent, then the
2329    <code>tRNS</code> chunk isn't written anyhow, and there is no effect
2330    on the PNG colortype of the output image.</p>
2331
2332    <p>The <a href="command-line-options.html#strip">-strip</a> option does the equivalent of the
2333    following for PNG output:</p>
2334
2335<pre class="highlight"><code>-define png:exclude-chunk=EXIF,iCCP,iTXt,sRGB,tEXt,zCCP,zTXt,date
2336</code></pre>
2337
2338    <p>The default behavior is to include all known PNG ancillary chunks
2339    plus ImageMagick's private <code>vpAg</code> ("virtual page") chunk,
2340    and to exclude all PNG chunks that are unknown to ImageMagick,
2341    regardless of their PNG "copy-safe" status as described in the
2342    PNG specification.</p>
2343
2344    <p>Any chunk names that are not known to ImageMagick are ignored
2345    if they appear in either the "include-chunk" or "exclude-chunk" list.
2346    The ancillary chunks currently known to ImageMagick are
2347    <code>bKGD</code>, <code>cHRM</code>, <code>gAMA</code>, <code>iCCP</code>,
2348    <code>oFFs</code>, <code>pHYs</code>, <code>sRGB</code>, <code>tEXt</code>,
2349    <code>tRNS</code>, <code>vpAg</code>, and <code>zTXt</code>.</p>
2350
2351    <p>You can also put <code>date</code> in the list to include or exclude
2352    the "Date:create" and "Date:modify" text chunks that ImageMagick normally
2353    inserts in the output PNG.</p></td>
2354  </tr>
2355
2356  <tr>
2357    <td>png:ignore-crc[=<var>true</var>]</td>
2358     <td>When you know your image has no CRC or ADLER32 errors, this can speed up
2359     decoding. It is also helpful in debugging bug reports from "fuzzers".</td>
2360  </tr>
2361
2362  <tr>
2363    <td>png:preserve-colormap[=<var>true</var>]</td>
2364     <td>Use the existing image->colormap. Normally the PNG encoder will
2365    try to optimize the palette, eliminating unused entries and putting
2366    the transparent colors first.  If this flag is set, that behavior
2367    is suppressed.</td>
2368  </tr>
2369
2370  <tr>
2371    <td>png:preserve-iCCP[=<var>true</var>]</td>
2372     <td>By default, the PNG decoder and encoder examine any ICC profile
2373    that is present, either from an <code>iCCP</code> chunk in the PNG
2374    input or supplied via an option, and if the profile is recognized
2375    to be the sRGB profile, converts it to the <code>sRGB</code> chunk.
2376    You can use <code>-define png:preserve-iCCP</code> to prevent
2377    this from happening; in such cases the <code>iCCP</code> chunk
2378    will be read or written and no <code>sRGB</code> chunk will be
2379    written.  There are some ICC profiles that claim to be sRGB but
2380    have various errors that cause them to be rejected by libpng16; such
2381    profiles are recognized anyhow and converted to the <code>sRGB</code>
2382    chunk, but are rejected if the <code>-define png:preserve-iCCP</code>
2383    is present. Note that not all "sRGB" ICC profiles are recognized
2384    yet; we will add them to the list as we encounter them.</td>
2385  </tr>
2386
2387  <tr>
2388    <td>png:swap-bytes[=<var>true</var>]</td>
2389     <td>The PNG specification requires that any multi-byte integers be stored in
2390    network byte order (MSB-LSB endian).  This option allows you to
2391    fix any invalid PNG files that have 16-bit samples stored incorrectly
2392    in little-endian order (LSB-MSB).  The "-define png:swap-bytes" option
2393    must appear before the input filename on the commandline.  The swapping
2394    is done during the libpng decoding operation.</td>
2395  </tr>
2396
2397  <tr>
2398    <td>profile:skip=<var>name1,name2,...</var></td>
2399     <td>Skip the named profile[s] when reading the image. Use skip="*" to
2400    skip all named profiles in the image. Many named profiles exist,
2401    including ICC, EXIF, APP1, IPTC, XMP, and others.</td>
2402  </tr>
2403
2404  <tr>
2405    <td>ps:imagemask</td>
2406     <td>If the ps:imagemask flag is defined, the PS3 and EPS3 coders will
2407    create Postscript files that render bilevel images with the Postscript
2408    imagemask operator instead of the image operator.</td>
2409  </tr>
2410
2411  <tr>
2412    <td>psd:additional-info=all|selective</td>
2413     <td>This option should only be used when converting from a PSD file to
2414     another PSD file. This should be placed after the image is read. The two
2415     options are 'all' and 'selective'. The 'selective' option will preserve
2416     all additional information that is not related to the geometry of the
2417     image. The 'all' option should only be used when the geometry of the
2418     image has not been changed. This option is helpful when transferring
2419     non-simple layers, such as adjustment layers from the input PSD file to
2420     the output PSD file. If this option is not used, the additional
2421     information will not be preserved. This define is available as of
2422     Imagemagick version 6.9.5-8.
2423</td>
2424  </tr>
2425
2426  <tr>
2427    <td>psd:alpha-unblend=off</td>
2428     <td>Disables new automatic un-blending of transparency with the base image
2429     for the flattened layer 0 before adding the alpha channel to the output
2430     image. This define must be placed before the input psd image. (Available
2431     as of IM 6.9.2.5). The automatic un-blending is new to IM 6.9.2.5 and
2432     prevents the transparency from being applied twice in the output
2433     image. This option should be set before reading the image.</td>
2434  </tr>
2435
2436  <tr>
2437    <td>psd:preserve-opacity-mask=true</td>
2438     <td>This option should only be used when converting from a PSD file to
2439     another PSD file. It will preserve the opacity mask of a layer and add it
2440     back to the layer when the image is saved. Setting this to 'true' will
2441     enable this feature. This define is available as of Imagemagick version
2442     6.9.5-10.
2443</td>
2444  </tr>
2445
2446  <tr>
2447    <td>preserve-timestamp=<var>{True, False}</var></td>
2448     <td>Preserve file timestamp (<code>mogrify</code> only).</td>
2449  </tr>
2450
2451  <tr>
2452    <td>q-table=<var>quantization-table.xml</var></td>
2453     <td>Custom JPEG quantization tables.</td>
2454  </tr>
2455
2456  <tr>
2457    <td>quantum:format=<var>type</var></td>
2458     <td>Set the type to <code>floating-point</code> to specify a floating-point
2459    format for raw files (e.g. GRAY:) or for MIFF and TIFF images in HDRI mode
2460    to preserve negative values. If <a href="command-line-options.html#depth">-depth</a> 16 is
2461    included, the result is a single precision floating point format.
2462    If <a href="command-line-options.html#depth">-depth</a> 32 is included, the result is
2463    double precision floating point format.</td>
2464  </tr>
2465
2466  <tr>
2467    <td>quantum:polarity=<var>photometric-interpretation</var></td>
2468     <td>Set the photometric-interpretation of an image (typically for TIFF
2469     image file format) to either <code>min-is-black</code> (default) or
2470    <code>min-is-white</code>.</td>
2471  </tr>
2472
2473  <tr>
2474    <td>sample:offset=<var>geometry</var></td>
2475     <td>Location of the sampling point within the sub-region being sampled,
2476    expressed as percentages (see <a href="command-line-options.html#sample" >-sample</a>).</td>
2477  </tr>
2478
2479  <tr>
2480    <td>morphology:showKernel=<var>1</var></td>
2481     <td>Outputs (to 'standard error') all the information about a generated <a
2482    href="command-line-options.html#morphology" >-morphology</a> kernel.</td>
2483  </tr>
2484
2485  <tr>
2486    <td>stream:buffer-size=<var>value</var></td>
2487   <td>Set the stream buffer size.  Select 0 for unbuffered I/O.</td>
2488  </tr>
2489
2490  <tr>
2491    <td>tiff:alpha=<var>associated|unassociated|unspecified</var></td>
2492    <td>Specify the alpha extra samples as associated, unassociated or
2493    unspecified.</td>
2494  </tr>
2495
2496  <tr>
2497    <td>tiff:endian=<var>msb|lsb</var></td>
2498    <td> </td>
2499  </tr>
2500
2501  <tr>
2502    <td>tiff:exif-properties=<var>true</var></td>
2503    <td>Enables reading the EXIF properties.</td>
2504  </tr>
2505
2506  <tr>
2507    <td>tiff:fill-order=<var>msb|lsb</var></td>
2508    <td> </td>
2509  </tr>
2510
2511  <tr>
2512    <td>tiff:ignore-layers=<var>true</var></td>
2513    <td>Ignores the photoshop layers.</td>
2514  </tr>
2515
2516  <tr>
2517    <td>tiff:ignore-tags=<var>comma-separate-list-of-tag-IDs</var></td>
2518    <td>Allows one or more tag ID values to be ignored.</td>
2519  </tr>
2520
2521  <tr>
2522    <td>tiff:predictor=<var>[1, 2 or 3]</var></td>
2523    <td>A mathematical operator that is applied to the image data before an encoding scheme is applied. The general idea is that subsequent pixels of an image resemble each other. Thus, substracting the information from a pixel that is already contained in previous one is likely to reduce its information density considerably and aid subsequent compression. 1 = No prediction scheme used before coding. 2 = Horizontal differencing. 3 = Floating point horizontal differencing.</td>
2524  </tr>
2525
2526  <tr>
2527    <td>tiff:rows-per-strip=<var>value</var></td>
2528    <td>Sets the number of rows per strip.</td>
2529  </tr>
2530
2531  <tr>
2532    <td>tiff:tile-geometry=<var>WxH</var></td>
2533    <td>Sets the tile size for pyramid tiffs. Requires the suffix
2534        PTIF: before the outputname.</td>
2535  </tr>
2536
2537  <tr>
2538    <td>type:features=<var>string</var></td>
2539    <td> </td>
2540  </tr>
2541
2542  <tr>
2543    <td>type:hinting=<var>off</var></td>
2544    <td> </td>
2545  </tr>
2546
2547  <tr>
2548    <td>txt:compliance=<var>css</var></td>
2549    <td>The first argument of a hsl() color is integer, not percentage.</td>
2550  </tr>
2551
2552  <tr>
2553    <td>x:screen=<var>true</var></td>
2554    <td>Obtains the image from the root window.</td>
2555  </tr>
2556
2557  <tr>
2558    <td>x:silent=<var>true</var></td>
2559    <td>Turns off the beep when importing an image.</td>
2560  </tr>
2561</table>
2562
2563<p>For example, to create a postscript file that will render only the black
2564pixels of a bilevel image, use:</p>
2565
2566<pre class="highlight"><code>convert bilevel.tif -define ps:imagemask eps3:stencil.ps
2567</code></pre>
2568
2569<p>Set attributes of the image registry by prefixing the value with
2570<code>registry:</code>.  For example, to set a temporary path to put work files,
2571use:</p>
2572
2573<pre class="highlight"><code>-define registry:temporary-path=/data/tmp
2574</code></pre>
2575
2576<div style="margin: auto;">
2577  <h3><a class="anchor" id="delay"></a>-delay <var>ticks</var> <br />-delay <var>ticks</var>x<var>ticks-per-second</var> {<var>&lt;</var>} {<var>&gt;</var>}</h3>
2578</div>
2579
2580<p class="magick-description">display the next image after pausing.</p>
2581
2582<p>This option is useful for regulating the animation of image sequences
2583<var>ticks/ticks-per-second</var> seconds must expire before the display of the
2584next image. The default is no delay between each showing of the image
2585sequence.  The default ticks-per-second is 100.</p>
2586
2587<p>Use <code>&gt;</code> to change the image delay <var>only</var> if its current
2588value exceeds the given delay. <code>&lt;</code> changes the image delay
2589<var>only</var> if current value is less than the given delay.  For example, if
2590you specify <code>30&gt;</code> and the image delay is 20, the image delay does
2591not change. However, if the image delay is 40 or 50, the delay it is changed
2592to 30. Enclose the given delay in quotation marks to prevent the
2593<code>&lt;</code> or <code>&gt;</code> from being interpreted by your shell as
2594a file redirection.</p>
2595
2596
2597<div style="margin: auto;">
2598  <h3><a class="anchor" id="delete"></a>-delete <var>indexes</var></h3>
2599</div>
2600
2601<p class="magick-description">delete the images specified by index, from the image sequence.</p>
2602
2603<p>Specify the image by its index in the sequence.  The first image is index
26040.  Negative indexes are relative to the end of the sequence, for example, -1
2605represents the last image of the sequence.  Specify a range of images with
2606a dash (e.g. 0-4).  Separate indexes with a comma (e.g. 0,2).  Use
2607<code>+delete</code> to delete the last image in the current image sequence. Use <code>-delete 0--1</code> to delete the entire image sequence.</p>
2608
2609
2610<div style="margin: auto;">
2611  <h3><a class="anchor" id="density"></a>-density <var>width</var><br />-density <var>width</var>x<var>height</var></h3>
2612</div>
2613
2614<p class="magick-description">Set the horizontal and vertical resolution of an image for rendering to devices.</p>
2615
2616<p>This option specifies the image resolution to store while encoding a raster
2617image or the canvas resolution while rendering (reading) vector formats such
2618as Postscript, PDF, WMF, and SVG into a raster image. Image resolution
2619provides the unit of measure to apply when rendering to an output device or
2620raster image. The default unit of measure is in dots per inch (DPI). The <a
2621href="command-line-options.html#units">-units</a> option may be used to select dots per centimeter
2622instead.</p>
2623
2624<p>The default resolution is 72 dots per inch, which is equivalent to one
2625point per pixel (Macintosh and Postscript standard). Computer screens are
2626normally 72 or 96 dots per inch, while printers typically support 150, 300,
2627600, or 1200 dots per inch. To determine the resolution of your display, use
2628a ruler to measure the width of your screen in inches, and divide by the
2629number of horizontal pixels (1024 on a 1024x768 display).</p>
2630
2631<p>If the file format supports it, this option may be used to update the
2632stored image resolution. Note that Photoshop stores and obtains image
2633resolution from a proprietary embedded profile. If this profile is not
2634stripped from the image, then Photoshop will continue to treat the image using
2635its former resolution, ignoring the image resolution specified in the standard
2636file header.</p>
2637
2638<p>The <a href="command-line-options.html#density">-density</a> option sets an <var>attribute</var> and
2639does not alter the underlying raster image. It may be used to adjust the
2640rendered size for desktop publishing purposes by adjusting the scale applied
2641to the pixels. To resize the image so that it is the same size at a different
2642resolution, use the <a href="command-line-options.html#resample">-resample</a> option.</p>
2643
2644<div style="margin: auto;">
2645  <h3><a class="anchor" id="depth"></a>-depth <var>value</var></h3>
2646</div>
2647
2648<p class="magick-description">depth of the image.</p>
2649
2650<p>This the number of bits in a color sample within a pixel.  Use this option
2651to specify the depth of raw images whose depth is unknown such as GRAY, RGB,
2652or CMYK, or to change the depth of any image after it has been read.</p>
2653
2654<p>Use <a href="command-line-options.html#depth">+depth</a> to return depth to its default value.</p>
2655
2656<div style="margin: auto;">
2657  <h3><a class="anchor" id="descend"></a>-descend</h3>
2658</div>
2659
2660<p class="magick-description">obtain image by descending window hierarchy.</p>
2661
2662<div style="margin: auto;">
2663  <h3><a class="anchor" id="deskew"></a>-deskew <var>threshold{%}</var></h3>
2664</div>
2665
2666<p class="magick-description">straighten an image.  A threshold of 40% works for most images.</p>
2667
2668<p>Use <a href="command-line-options.html#set">-set</a> <code>option:deskew:auto-crop
2669<var>true | false</var></code> to auto crop the image.</p>
2670
2671<div style="margin: auto;">
2672  <h3><a class="anchor" id="despeckle"></a>-despeckle</h3>
2673</div>
2674
2675<p class="magick-description">reduce the speckles within an image.</p>
2676
2677<div style="margin: auto;">
2678  <h3><a class="anchor" id="direction"></a>-direction <var>type</var></h3>
2679</div>
2680
2681<p class="magick-description">render text right-to-left or left-to-right.  Requires the <a href="https://github.com/HOST-Oman/libraqm">RAQM</a> delegate library and <a href="https://en.wikipedia.org/wiki/Complex_text_layout">complex text layout</a>.</p>
2682
2683<div style="margin: auto;">
2684  <h3><a class="anchor" id="displace"></a>-displace <var>horizontal-scale</var>{%}{!}<br />-displace <var>horizontal-scale</var>x<var>vertical-scale</var>{%}{!}</h3>
2685</div>
2686
2687<p class="magick-description">shift image pixels as defined by a displacement map.</p>
2688
2689<p>With this option, the 'overlay' image, and optionally the 'mask' image,
2690is used as a displacement map, which is used to displace the lookup of
2691what part of the 'background' image is seen at each point of the overlaid
2692area.  Much like the displacement map is a 'lens' that redirects light shining
2693through it so as to present a distorted view the original 'background' image
2694behind it. </p>
2695
2696<p>Any perfect grey areas of the displacement map produce a zero
2697displacement of the image. Black areas produce the given maximum negative
2698displacement of the lookup point, while white produce a maximum positive
2699displacement of the lookup. </p>
2700
2701<p>Note that it is the lookup of the 'background' that is displaced, not a
2702displacement of the image itself. As such an area of the displacement map
2703containing 'white' will have the lookup point 'shifted' by a positive amount,
2704and thus generating a copy of the destination image to the right/downward from
2705the correct position.  That is the image will look like it may have been
2706'shifted' in a negative left/upward direction.  Understanding this is a very
2707important in understanding how displacement maps work.  </p>
2708
2709<p>The given arguments define the maximum amount of displacement in pixels
2710that a particular map can produce. If the displacement scale is large enough
2711it is also possible to lookup parts of the 'background' image that lie well
2712outside the bounds of the displacement map itself.  That is you could very
2713easily copy a section of the original image from outside the overlay area
2714into the overlay area. </p>
2715
2716<p>The '%' flag makes the displacement scale relative to the size of the
2717overlay image (100% = half width/height of image). Using '!' switches
2718percentage arguments to refer to the destination image size instead.
2719these flags were added as of IM v6.5.3-5.</p>
2720
2721<p>Normally a single grayscale displacement map is provided, which with the
2722given scaling values will determine a single direction (vector) in which
2723displacements can occur (positively or negatively).  However, if you also
2724specify a third image which is normally used as a <var>mask</var>,
2725the <var>composite image</var> is used for horizontal X
2726displacement, while the <var>mask image</var> is used for vertical Y
2727displacement.  This allows you to define completely different displacement
2728values for the X and Y directions, and allowing you to lookup any point within
2729the  <var>scale</var> bounds.  In other words each pixel can lookup
2730any other nearby pixel, producing complex 2 dimensional displacements, rather
2731than a simple 1 dimensional vector displacements. </p>
2732
2733<p>Alternatively rather than supplying two separate images, as of IM v6.4.4-0,
2734you can use the 'red' channel of the overlay image to specify the horizontal
2735or X displacement, and the 'green' channel for the vertical or Y displacement.
2736</p>
2737
2738<p>As of IM v6.5.3-5 any alpha channel in the overlay image is used as a
2739mask the transparency of the destination image. However areas outside the
2740overlaid areas will not be affected. </p>
2741
2742
2743<div style="margin: auto;">
2744  <h3><a class="anchor" id="display"></a>-display <var>host:display[.screen]</var></h3>
2745</div>
2746
2747<p class="magick-description">Specifies the X server to contact.</p>
2748
2749<p>This option is used with convert for obtaining image or font from this
2750X server. See <var>X(1)</var>.</p>
2751
2752<div style="margin: auto;">
2753  <h3><a class="anchor" id="dispose"></a>-dispose <var>method</var></h3>
2754</div>
2755
2756<p class="magick-description">define the GIF disposal image setting for images that are being created or read in. </p>
2757
2758<p>The layer disposal method defines the way each the displayed image is to be
2759modified after the current 'frame' of an animation has finished being
2760displayed (after its 'delay' period), but before the next frame on an
2761animation is to be overlaid onto the display. </p>
2762
2763<p>Here are the valid methods:</p>
2764
2765<dl class="row">
2766<dt class="col-md-4">Undefined</dt><dd class="col-md-8">0:  No disposal specified (equivalent to '<code>none</code>').</dd>
2767<dt class="col-md-4">None</dt><dd class="col-md-8">1:  Do not dispose, just overlay next frame image.</dd>
2768<dt class="col-md-4">Background</dt><dd class="col-md-8">2:  Clear the frame area with the background color.</dd>
2769<dt class="col-md-4">Previous</dt><dd class="col-md-8">3:  Clear to the image prior to this frames overlay.</dd>
2770</dl>
2771
2772<p>You can also use the numbers given above, which is what the GIF format
2773uses internally to represent the above settings. </p>
2774
2775<p>To print a complete list of dispose methods, use <a href="command-line-options.html#list">-list dispose</a>.</p>
2776
2777<p>Use <a href="command-line-options.html#dispose" >+dispose</a>, turn off the setting and prevent
2778resetting the layer disposal methods of images being read in. </p>
2779
2780<p>Use <a href="command-line-options.html#set">-set</a> '<code>dispose</code>' method to set the image
2781disposal method for images already in memory.</p>
2782
2783<div style="margin: auto;">
2784  <h3><a class="anchor" id="dissimilarity-threshold"></a>-dissimilarity-threshold <var>value</var></h3>
2785</div>
2786
2787<p class="magick-description">maximum RMSE for subimage match (default 0.2).</p>
2788
2789
2790<div style="margin: auto;">
2791  <h3><a class="anchor" id="dissolve"></a>-dissolve <var>src_percent</var>[x<var>dst_percent</var>]</h3>
2792</div>
2793
2794<p class="magick-description">dissolve an image into another by the given percent.</p>
2795
2796<p>The opacity of the composite image is multiplied by the given percent, then
2797it is composited 'over' the main image.  If <var>src_percent</var>
2798is greater than 100, start dissolving the main image so it becomes
2799transparent at a value of '<code>200</code>'.  If both percentages
2800are given, each image are dissolved to the percentages given. </p>
2801
2802<p>Note that dissolve percentages do not add, two opaque images dissolved
2803'50,50', produce a 75% transparency. For a 50% + 50% blending of the two
2804images, you would need to use dissolve values of '50,100'.  </p>
2805
2806<div style="margin: auto;">
2807  <h3><a class="anchor" id="distort"></a>-distort <var>method arguments</var></h3>
2808</div>
2809
2810<p class="magick-description">distort an image, using the given <var>method</var> and its required <var>arguments</var>.</p>
2811
2812<p>The <var>arguments</var> is a single string containing a list
2813of floating point numbers separated by commas or spaces.  The number of
2814and meaning of the floating point values depends on the distortion <var>method</var> being used. </p>
2815
2816<p>Choose from these distortion types:</p>
2817
2818<table class="table table-sm table-striped">
2819  <tr>
2820    <th style="width: 8%">Method</th>
2821    <th>Description</th>
2822  </tr>
2823
2824  <tr>
2825    <td>ScaleRotateTranslate <br/> SRT</td>
2826    <td>
2827       Distort image by first scaling and rotating about a given 'center',
2828       before translating that 'center' to the new location, in that order. It
2829       is an alternative method of specifying a 'Affine' type of
2830       distortion, but without shearing effects.  It also provides a good way
2831       of rotating and displacing a smaller image for tiling onto a larger
2832       background (IE 2-dimensional animations). <br/>
2833
2834       The number of arguments determine the specific meaning of each
2835       argument for the scales, rotation, and translation operations. <br/>
2836
2837       <dl class="row">
2838       <dt class="col-md-4">2:</dt><dd class="col-md-8"><var>Scale   Angle</var></dd>
2839       <dt class="col-md-4">3:</dt><dd class="col-md-8"><var>X,Y     Angle</var></dd>
2840       <dt class="col-md-4">4:</dt><dd class="col-md-8"><var>X,Y   Scale   Angle</var></dd>
2841       <dt class="col-md-4">5:</dt> <dd class="col-md-8"><var>X,Y   ScaleX,ScaleY   Angle</var></dd>
2842       <dt class="col-md-4">6:</dt> <dd class="col-md-8"><var>X,Y   Scale   Angle   NewX,NewY</var></dd>
2843       <dt class="col-md-4">7:</dt> <dd class="col-md-8"><var>X,Y   ScaleX,ScaleY   Angle NewX,NewY</var></dd>
2844       </dl>
2845
2846       This is actually an alternative way of specifying a 2 dimensional linear
2847       'Affine' or 'AffineProjection' distortion.  </td> </tr>
2848
2849  <tr>
2850    <td>Affine</td>
2851    <td>
2852       Distort the image linearly by moving a list of at least 3 or more sets
2853       of control points (as defined below).  Ideally 3 sets or 12 floating
2854       point values are given allowing the image to be linearly scaled,
2855       rotated, sheared, and translated, according to those three points. See
2856       also the related 'AffineProjection' and 'SRT'
2857       distortions. <br/>
2858
2859       More than 3 sets given control point pairs (12 numbers) is least
2860       squares fitted to best match a linear affine distortion. If only 2
2861       control point pairs (8 numbers) are given a two point image translation
2862       rotation and scaling is performed, without any possible  shearing,
2863       flipping or changes in aspect ratio to the resulting image. If only one
2864       control point pair is provides the image is only translated, (which may
2865       be a floating point non-integer translation). <br/>
2866
2867       This distortion does not include any form of perspective distortion.
2868       </td>
2869
2870  </tr>
2871
2872  <tr>
2873    <td>AffineProjection</td>
2874    <td>
2875       Linearly distort an image using the given Affine Matrix of 6
2876       pre-calculated coefficients forming a set of Affine Equations to map
2877       the source image to the destination image.
2878
2879       <p class="text-center"><var>
2880       s<sub>x</sub>, r<sub>x</sub>,
2881       r<sub>y</sub>, s<sub>y</sub>,
2882       t<sub>x</sub>, t<sub>y</sub>
2883       </var></p>
2884
2885       See <a href="command-line-options.html#affine" >-affine</a> setting for more detail, and
2886       meanings of these coefficients. <br/>
2887
2888       The distortions 'Affine' and 'SRT' provide
2889       alternative methods of defining this distortion, with ImageMagick doing
2890       the calculations needed to generate the required coefficients. You can
2891       see the internally generated coefficients, by using a <a
2892       href="command-line-options.html#verbose" >-verbose</a> setting with those other variants.  </td>
2893
2894  </tr>
2895
2896  <tr>
2897    <td>BilinearForward<br/>
2898    BilinearReverse</td>
2899    <td>
2900       Bilinear Distortion, given a minimum of 4 sets of coordinate pairs, or
2901       16 values (see below). Not that lines may not appear straight after
2902       distortion, though the distance between coordinates will remain
2903       consistent. <br/>
2904
2905       The 'BilinearForward' is used to map rectangles to any
2906       quadrilateral, while the 'BilinearReverse' form maps any
2907       quadrilateral to a rectangle, while preserving the straight line edges
2908       in each case.  <br/>
2909
2910       Note that 'BilinearForward' can generate invalid pixels
2911       which will be colored using the <a href="command-line-options.html#mattecolor" >-mattecolor</a>
2912       color setting.  Also if the quadrilateral becomes 'flipped' the image
2913       may disappear. <br/>
2914
2915       There are future plans to produce a true Bilinear distortion that will
2916       attempt to map any quadrilateral to any other quadrilateral, while
2917       preserving edges (and edge distance ratios).
2918
2919       </td>
2920  </tr>
2921
2922  <tr>
2923    <td>Perspective</td>
2924    <td>
2925       Perspective distort the images, using a list of 4 or more sets of
2926       control points (as defined below).  More that 4 sets (16 numbers) of
2927       control points provide least squares fitting for more accurate
2928       distortions (for the purposes of image registration and panorama
2929       effects).  Less than 4 sets will fall back to a 'Affine'
2930       linear distortion.  <br/>
2931
2932       Perspective Distorted images ensures that straight lines remain
2933       straight, but the scale of the distorted image will vary. The horizon
2934       is anti-aliased, and the 'sky' color may be set using the
2935       <a href="command-line-options.html#mattecolor" >-mattecolor</a> setting. </td>
2936  </tr>
2937
2938  <tr>
2939    <td>PerspectiveProjection  </td>
2940    <td>
2941       Do a 'Perspective' distortion biased on a set of 8
2942       pre-calculated coefficients. You can get these coefficients by looking
2943       at the <a href="command-line-options.html#verbose" >-verbose</a> output of a
2944       'Perspective' distortion, or by calculating them yourself.
2945       If the last two perspective scaling coefficients are zero, the
2946       remaining 6 represents a transposed 'Affine Matrix'. </td>
2947
2948  </tr>
2949
2950  <tr>
2951    <td>Arc</td>
2952    <td>
2953       Arc the image (variation of polar mapping) over the angle given around
2954       a circle.
2955
2956       <dl class="row">
2957       <dt class="col-md-4">arc_angle</dt>
2958           <dd class="col-md-8">The angle over which to arc the image side-to-side</dd>
2959       <dt class="col-md-4">rotate_angle</dt>
2960           <dd class="col-md-8">Angle to rotate resulting image from vertical center</dd>
2961       <dt class="col-md-4">top_radius</dt>
2962           <dd class="col-md-8">Set top edge of source image at this radius</dd>
2963       <dt class="col-md-4">bottom_radius </dt>
2964           <dd class="col-md-8">Set bottom edge to this radius (radial scaling)</dd>
2965       </dl>
2966
2967       The resulting image is always resized to best fit the resulting image,
2968       (as if using <a href="command-line-options.html#distort" >+distort</a>) while attempting to
2969       preserve scale and aspect ratio of the original image as much as
2970       possible with the arguments given by the user. All four arguments will
2971       be needed to change the overall aspect ratio of an 'Arc'ed image. <br/>
2972
2973       This a variation of a polar distortion designed to try to preserve the
2974       aspect ratio of the image rather than direct Cartesian to Polar
2975       conversion. </td>
2976  </tr>
2977
2978  <tr>
2979    <td>Polar</td>
2980    <td>
2981       Like 'Arc' but do a complete Cartesian to Polar mapping of
2982       the image. that is the height of the input image is mapped to the
2983       radius limits, while the width is wrapped around between the
2984       angle limits. <br/>
2985
2986       Arguments: <var>Rmax,Rmin CenterX,CenterY, start,end_angle</var> <br/>
2987
2988       All arguments are optional. With <var>Rmin</var> defaulting to zero, the
2989       center to the center of the image, and the angles going from -180 (top)
2990       to +180 (top).  If <var>Rmax</var> is given the special value of
2991       '0', the the distance from the center to the nearest edge
2992       is used for the radius of the output image, which will ensure the whole
2993       image is visible (though scaled smaller).  However a special value of
2994       '-1' will use the distance from the center to the furthest
2995       corner,  This may 'clip' the corners from the input rectangular image,
2996       but will generate the exact reverse of a 'DePolar' with
2997       the same arguments. <br/>
2998
2999       If the plus form of distort (<a href="command-line-options.html#distort" >+distort</a>) is used
3000       output image center will default to 0,0 of the virtual
3001       canvas, and the image size adjusted to ensure the whole input image is
3002       made visible in the output image on the virtual canvas. </td>
3003
3004  </tr>
3005
3006  <tr>
3007    <td>DePolar</td>
3008    <td>
3009       Uses the same arguments and meanings as a 'Polar' distortion
3010       but generates the reverse Polar to Cartesian distortion. <br/>
3011
3012       The special <var>Rmax</var> setting of '0' may however clip
3013       the corners of the input image.  However using the special
3014       <var>Rmax</var> setting of '-1' (maximum center to corner
3015       distance) will ensure the whole distorted image is preserved in the
3016       generated result, so that the same argument to 'Polar' will
3017       reverse the distortion re-producing the original.
3018
3019       Note that as this distortion requires the area resampling of a circular
3020       arc, which can not be handled by the builtin EWA resampling function.
3021       As such the normal EWA filters are turned off. It is recommended some
3022       form of 'super-sampling' image processing technique be used to produce
3023       a high quality result. </td>
3024
3025  </tr>
3026
3027  <tr>
3028    <td>Barrel</td>
3029    <td>
3030       Given the four coefficients (A,B,C,D) as defined by <a
3031       href="http://wiki.panotools.org/Lens_correction_model" >Helmut
3032       Dersch</a>, perform a barrel or pin-cushion distortion appropriate to
3033       correct radial lens distortions.  That is in photographs, make straight
3034       lines straight again. <br/>
3035
3036       <p class="text-center">Arguments: <var>A   B   C</var>   [ <var>D</var>   [
3037       <var>X</var> , <var>Y</var> ] ] <br/>
3038       or <var>A<sub>x</sub> B<sub>x</sub> C<sub>x</sub> D<sub>x</sub>
3039       A<sub>y</sub> B<sub>y</sub> C<sub>y</sub> D<sub>y</sub></var>
3040       [ <var>X</var> , <var>Y</var> ] </p>
3041       So that it forms the function
3042       <p class="text-center">Rsrc = r * ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
3043                               <var>C</var>*r + <var>D</var> )</p>
3044
3045       Where <var>X</var>,<var>Y</var> is the optional center of the distortion
3046       (defaulting to the center of the image). <br/>
3047       The second form is typically used to distort images, rather than
3048       correct lens distortions. <br/>
3049       </td>
3050
3051  </tr>
3052
3053  <tr>
3054    <td>BarrelInverse</td>
3055    <td>
3056       This is very similar to 'Barrel' with the same set of
3057       arguments, and argument handling.  However it uses the inverse
3058       of the radial polynomial,
3059       so that it forms the function
3060       <p class="text-center">Rsrc = r / ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
3061                               <var>C</var>*r + <var>D</var> )</p>
3062       Note that this is not the reverse of the 'Barrel'
3063       distortion, just a different barrel-like radial distortion method.
3064
3065       </td>
3066  </tr>
3067
3068  <tr>
3069    <td>Shepards</td>
3070    <td>
3071       Distort the given list control points (any number) using an Inverse
3072       Squared Distance Interpolation Method (<a
3073       href="http://en.wikipedia.org/wiki/Shepard%27s_method" >Shepards
3074       Method</a>). The control points in effect do 'localized' displacement
3075       of the image around the given control point (preserving the look and
3076       the rotation of the area near the control points.  For best results
3077       extra control points should be added to 'lock' the positions of the
3078       corners, edges and other unchanging parts of the image, to prevent
3079       their movement. <br/>
3080
3081       The distortion has been likened to 'taffy pulling' using nails, or
3082       pins' stuck in a block of 'jelly' which is then moved to the new
3083       position, distorting the surface of the jelly. <br/>
3084
3085       Internally it is equivalent to generating a displacement map (see <a
3086       href="command-line-options.html#displace" >-displace</a>) for source image color look-up using
3087       the <a href="command-line-options.html#sparse-color" >-sparse-color</a> method of the same name.
3088
3089       </td>
3090  </tr>
3091
3092</table>
3093
3094<p>To print a complete list of distortion methods, use <a href="command-line-options.html#list">-list
3095distort</a>.</p>
3096
3097<p>Many of the above distortion methods such as '<code>Affine</code>',
3098'<code>Perspective</code>', and '<code>Shepards</code>' use a list control points
3099defining how these points in the given image should be distorted in the
3100destination image. Each set of four floating point values represent a source
3101image coordinate, followed immediately by the destination image coordinate.
3102This produces a list of values such as...</p>
3103<p class="text-center"><var>
3104      U<sub>1</sub>,V<sub>1</sub> X<sub>1</sub>,Y<sub>1</sub>
3105      U<sub>2</sub>,V<sub>2</sub> X<sub>2</sub>,Y<sub>2</sub>
3106      U<sub>3</sub>,V<sub>3</sub> X<sub>3</sub>,Y<sub>3</sub>
3107      ...
3108      U<sub>n</sub>,V<sub>n</sub> X<sub>n</sub>,Y<sub>n</sub>
3109</var></p>
3110<p>where <var>U,V</var> on the source image is mapped to <var>X,Y</var> on the
3111destination image. </p>
3112
3113<p>For example, to warp an image using '<code>perspective</code>' distortion,
3114needs a list of at least 4 sets of coordinates, or 16 numbers.  Here is the
3115perspective distortion of the built-in "rose:" image. Note how spaces were
3116used to group the 4 sets of coordinate pairs, to make it easier to read and
3117understand.</p>
3118
3119<pre class="highlight"><code>convert rose:  -virtual-pixel black \
3120  -distort Perspective '0,0,0,0  0,45,0,45  69,0,60,10  69,45,60,35' \
3121   rose_3d_rotated.gif"
3122</code></pre>
3123
3124<p>If more that the required number of coordinate pairs are given for
3125a distortion, the distortion method is 'least squares' fitted to produce the
3126best result for all the coordinate pairs given. If less than the ideal number
3127of points are given, the distort will generally fall back to a simpler form of
3128distortion that can handles the smaller number of coordinates (usually a linear
3129'<code>Affine</code>' distortion). </p>
3130
3131<p>By using more coordinates you can make use of image registration tool to
3132find matching coordinate pairs in overlapping images, so as to improve the
3133'fit' of the distortion. Of course a bad coordinate pair can also make the
3134'fit' worse. Caution is always advised. </p>
3135
3136<p>Colors are acquired from the source image according to a cylindrical
3137resampling <a href="command-line-options.html#filter" >-filter</a>, using a special technique known as
3138EWA resampling. This produces very high quality results, especially when
3139images become smaller (minified) in the output, which is very common when
3140using '<code>perspective</code>' distortion. For example here we view
3141a infinitely tiled 'plane' all the way to the horizon. </p>
3142
3143<pre class="highlight"><code>convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \
3144  -distort perspective  '0,0,5,45  89,0,45,46  0,89,0,89  89,89,89,89' \
3145   checks_tiled.jpg
3146</code></pre>
3147
3148<p>Note that a infinitely tiled perspective images involving the horizon can
3149be very slow, because of the number of pixels that are compressed to generate
3150each individual pixel close to the 'horizon'.  You can turn off EWA
3151resampling, by specifying the special <a href="command-line-options.html#filter" >-filter</a> setting of
3152'<code>point</code>' (recommended if you plan to use super-sampling instead).
3153</p>
3154
3155<p>If an image generates <i>invalid pixels</i>, such as the 'sky' in the last
3156example, <a href="command-line-options.html#distort" >-distort</a> will use the current <a
3157href="command-line-options.html#mattecolor" >-mattecolor</a> setting for these pixels. If you do not
3158what these pixels to be visible, set the color to match the rest of the
3159ground. </p>
3160
3161<p>The output image size will by default be the same as the input image.  This
3162means that if the part of the distorted image falls outside the viewed area of
3163the 'distorted space', those parts is clipped and lost.  However if you use
3164the plus form of the operator (<a href="command-line-options.html#distort" >+distort</a>) the operator
3165will attempt (if possible) to show the whole of the distorted image, while
3166retaining a correct 'virtual canvas' offset, for image layering. This offset
3167may need to be removed using <a href="command-line-options.html#repage" >+repage</a>, to remove if it
3168is unwanted. </p>
3169
3170<p>Setting <a href="command-line-options.html#verbose" >-verbose</a> setting, will cause <a
3171href="command-line-options.html#distort" >-distort</a> to attempt to output the internal coefficients,
3172and the <a href="command-line-options.html#fx" >-fx</a> equivalent to the distortion, for expert study,
3173and debugging purposes. This many not be available for all distorts. </p>
3174
3175<p>You can alternatively specify a special "<code><a href="command-line-options.html#define"
3176>-define</a> distort:viewport={geometry_string}</code>" setting which will
3177specify the size and the offset of the generated 'viewport' image of the
3178distorted image space.</p>
3179
3180<p>Setting a "<code><a href="command-line-options.html#define" >-define</a>
3181distort:scale=<var>scale_factor</var></code>" will scale the output image (viewport or
3182otherwise) by that factor without changing the viewed contents of the
3183distorted image. This can be used either for 'super-sampling' the image for
3184a higher quality result, or for panning and zooming around the image (with
3185appropriate viewport changes, or post-distort cropping and resizing). </p>
3186
3187<p>Setting "<code><a href="command-line-options.html#define" >-define</a> resample:verbose=1</code>"
3188will output the cylindrical filter lookup table created by the EWA (Elliptical
3189Weighted Average) resampling algorithm. Note this table uses a squared radius
3190lookup value. This is typically only used for debugging EWA resampling. </p>
3191
3192
3193<div style="margin: auto;">
3194  <h3><a class="anchor" id="distribute-cache"></a>-distribute-cache <var>port</var></h3>
3195</div>
3196
3197<p class="magick-description">launch a distributed pixel cache server. </p>
3198
3199<div style="margin: auto;">
3200  <h3><a class="anchor" id="dither"></a>-dither <var>method</var></h3>
3201</div>
3202
3203<p class="magick-description">Apply a Riemersma or Floyd-Steinberg error diffusion dither to
3204images when general color reduction is applied via an option, or automagically
3205when saving to specific formats. This enabled by default.</p>
3206
3207<p>Dithering places two or more colors in neighboring pixels so that to the
3208eye a closer approximation of the images original color is reproduced. This
3209reduces the number of colors needed to reproduce the image but at the cost of
3210a lower level pattern of colors. Error diffusion dithers can use any set of
3211colors (generated or user defined) to an image.  </p>
3212
3213<p>Dithering is turned on by default, to turn it off use the plus form of the
3214setting, <a href="command-line-options.html#dither">+dither</a>. This will also also render PostScript
3215without text or graphic aliasing. Disabling dithering often (but not always)
3216leads to faster process, a smaller number of colors, but more cartoon like
3217image coloring.  Generally resulting in 'color banding' effects in areas with
3218color gradients. </p>
3219
3220<p>The color reduction operators <a href="command-line-options.html#colors">-colors</a>, <a
3221href="command-line-options.html#monochrome">-monochrome</a>, <a href="command-line-options.html#remap ">-remap</a>, and <a
3222href="command-line-options.html#posterize">-posterize</a>, apply dithering to images using the reduced
3223color set they created. These operators are also used as part of automatic
3224color reduction when saving images to formats with limited color support, such
3225as <code>GIF:</code>, <code>XBM:</code>, and others, so dithering may also be used
3226in these cases. </p>
3227
3228<p>Alternatively you can use <a href="command-line-options.html#random-threshold">-random-threshold</a>
3229to generate purely random dither. Or use <a
3230href="command-line-options.html#ordered-dither">-ordered-dither</a> to apply threshold mapped dither
3231patterns, using uniform color maps, rather than specific color maps. </p>
3232<p>Use "<code><a href="command-line-options.html#define" >-define</a> dither:diffusion-amount=35%</code>, for example, to control the amount of Floyd-Steinberg dither.</p>
3233
3234
3235<div style="margin: auto;">
3236  <h3><a class="anchor" id="draw"></a>-draw <var>string</var></h3>
3237</div>
3238
3239<p class="magick-description">Annotate an image with one or more graphic primitives.</p>
3240
3241<p>Use this option to annotate or decorate an image with one or more graphic
3242primitives. The primitives include shapes, text, transformations, and pixel
3243operations.</p>
3244
3245<p>The shape primitives:</p>
3246
3247<dl class="row">
3248<dt class="col-md-4">point</dt><dd class="col-md-8">          x,y</dd>
3249<dt class="col-md-4">line</dt><dd class="col-md-8">           x0,y0 x1,y1</dd>
3250<dt class="col-md-4">rectangle</dt><dd class="col-md-8">      x0,y0 x1,y1</dd>
3251<dt class="col-md-4">roundRectangle</dt><dd class="col-md-8"> x0,y0 x1,y1 wc,hc</dd>
3252<dt class="col-md-4">arc</dt><dd class="col-md-8">            x0,y0 x1,y1 a0,a1</dd>
3253<dt class="col-md-4">ellipse</dt><dd class="col-md-8">        x0,y0 rx,ry a0,a1</dd>
3254<dt class="col-md-4">circle</dt><dd class="col-md-8">         x0,y0 x1,y1</dd>
3255<dt class="col-md-4">polyline</dt><dd class="col-md-8">       x0,y0  ...  xn,yn</dd>
3256<dt class="col-md-4">polygon</dt><dd class="col-md-8">        x0,y0  ...  xn,yn</dd>
3257<dt class="col-md-4">bezier</dt><dd class="col-md-8">         x0,y0  ...  xn,yn</dd>
3258<dt class="col-md-4">path</dt><dd class="col-md-8">specification  </dd>
3259<dt class="col-md-4">image</dt><dd class="col-md-8">          operator x0,y0 w,h filename</dd>
3260</dl>
3261
3262<p>The text primitive:</p>
3263
3264<dl class="row">
3265<dt class="col-md-4">text</dt><dd class="col-md-8">x0,y0 string</dd>
3266</dl>
3267<p>The text gravity primitive:</p>
3268
3269<dl class="row">
3270<dt class="col-md-4">gravity</dt><dd class="col-md-8">NorthWest, North, NorthEast, West, Center, East, SouthWest, South, or SouthEast</dd>
3271</dl>
3272
3273<p>The text gravity primitive only affects the placement of text and does not
3274interact with the other primitives.  It is equivalent to using the <a
3275href="command-line-options.html#gravity">-gravity</a> command-line option, except that it is limited in
3276scope to the <a href="command-line-options.html#draw">-draw</a> option in which it appears.</p>
3277
3278<p>The transformation primitives:</p>
3279
3280<dl class="row">
3281<dt class="col-md-4">rotate</dt><dd class="col-md-8">degrees</dd>
3282<dt class="col-md-4">translate</dt><dd class="col-md-8">dx,dy</dd>
3283<dt class="col-md-4">scale</dt><dd class="col-md-8">sx,sy</dd>
3284<dt class="col-md-4">skewX</dt><dd class="col-md-8">degrees</dd>
3285<dt class="col-md-4">skewY</dt><dd class="col-md-8">degrees</dd>
3286</dl>
3287
3288<p>The pixel operation primitives:</p>
3289
3290<dl class="row">
3291<dt class="col-md-4">color</dt><dd class="col-md-8">x0,y0 method</dd>
3292<dt class="col-md-4">matte</dt><dd class="col-md-8">x0,y0 method</dd>
3293</dl>
3294
3295<p>The shape primitives are drawn in the color specified by the preceding <a
3296href="command-line-options.html#fill">-fill</a> setting.  For unfilled shapes, use <a
3297href="command-line-options.html#fill">-fill none</a>.  You can optionally control the stroke (the
3298"outline" of a shape) with the <a href="command-line-options.html#stroke">-stroke</a> and <a
3299href="command-line-options.html#strokewidth">-strokewidth</a> settings.</p>
3300
3301<p>A <code>point</code> primitive is specified by a single <var>point</var> in the
3302pixel plane, that is, by an ordered pair of integer coordinates,
3303<var>x</var>,<var>y</var>. (As it involves only a single pixel, a <code>point</code>
3304primitive is not affected by <a href="command-line-options.html#stroke">-stroke</a> or <a
3305href="command-line-options.html#strokewidth">-strokewidth</a>.)</p>
3306
3307<p>A <code>line</code> primitive requires a start point and end point.</p>
3308
3309<p>A <code>rectangle</code> primitive is specified by the pair of points at the
3310upper left and lower right corners.</p>
3311
3312<p>A <code>roundRectangle</code> primitive takes the same corner points as
3313a <code>rectangle</code> followed by the width and height of the rounded corners
3314to be removed.</p>
3315
3316<p>The <code>circle</code> primitive makes a disk (filled) or circle (unfilled).
3317Give the center and any point on the perimeter (boundary).</p>
3318
3319<p>The <code>arc</code> primitive is used to inscribe an elliptical segment in
3320to a given rectangle. An <code>arc</code> requires the two corners used for
3321<code>rectangle</code> (see above) followed by the start and end angles of the
3322arc of the segment segment (e.g. 130,30 200,100 45,90). The start and end
3323points produced are then joined with a line segment and the resulting segment
3324of an ellipse is filled.</p>
3325
3326<p>Use <code>ellipse</code> to draw a partial (or whole) ellipse. Give the
3327center point, the horizontal and vertical "radii" (the <var>semi-axes</var> of
3328the ellipse) and start and end angles in degrees (e.g. 100,100 100,150
33290,360).</p>
3330
3331<p>The <code>polyline</code> and <code>polygon</code> primitives require three or
3332more points to define their perimeters. A <code>polyline</code> is simply
3333a <code>polygon</code> in which the final point is not stroked to the start
3334point. When unfilled, this is a <var>polygonal line</var>. If the <a
3335href="command-line-options.html#stroke">-stroke</a> setting is <code>none</code> (the default), then
3336a <code>polyline</code> is identical to a <code>polygon</code>.  </p>
3337
3338<p>A <var>coordinate</var> is a pair of integers separated by a space or
3339optional comma. </p>
3340
3341<p>As an example, to define a circle centered at 100,100 that extends to
3342150,150 use:</p>
3343
3344<pre class="highlight"><code>-draw 'circle 100,100 150,150'
3345</code></pre>
3346
3347<p>The <code>Bezier</code> primitive creates a spline curve and requires three
3348or points to define its shape. The first and last points are the
3349<var>knots</var> and these points are attained by the curve, while any
3350intermediate coordinates are <var>control points</var>. If two control points
3351are specified, the line between each end knot and its sequentially respective
3352control point determines the tangent direction of the curve at that end. If
3353one control point is specified, the lines from the end knots to the one
3354control point determines the tangent directions of the curve at each end. If
3355more than two control points are specified, then the additional control points
3356act in combination to determine the intermediate shape of the curve. In order
3357to draw complex curves, it is highly recommended either to use the
3358<code>path</code> primitive or to draw multiple four-point bezier segments with
3359the start and end knots of each successive segment repeated. For example:</p>
3360
3361<pre class="highlight"><code>-draw 'bezier 20,50 45,100 45,0 70,50'
3362-draw 'bezier 70,50 95,100 95,0 120,50'
3363</code></pre>
3364
3365<p>A <code>path</code> represents an outline of an object, defined in terms of
3366moveto (set a new current point), lineto (draw a straight line), curveto (draw
3367a Bezier curve), arc (elliptical or circular arc) and closepath (close the
3368current shape by drawing a line to the last moveto) elements. Compound paths
3369(i.e., a path with subpaths, each consisting of a single moveto followed by
3370one or more line or curve operations) are possible to allow effects such as
3371<var>donut holes</var> in objects. (See <a
3372href="http://www.w3.org/TR/SVG/paths.html">Paths</a>.)</p>
3373
3374<p>Use <code>image</code> to composite an image with another image. Follow the
3375image keyword with the composite operator, image location, image size, and
3376filename:</p>
3377
3378<pre class="highlight"><code>-draw 'image SrcOver 100,100 225,225 image.jpg'
3379</code></pre>
3380
3381<p>You can use 0,0 for the image size, which means to use the actual
3382dimensions found in the image header. Otherwise, it is scaled to the given
3383dimensions. See <a href="../www/compose.html">Alpha Compositing</a> for
3384a detailed discussion of alpha composition methods that are available. </p>
3385
3386<p>The "special augmented compose operators" such as "dissolve" that require
3387arguments cannot be used at present with the <code>-draw image</code> option.
3388 </p>
3389
3390<p>Use <code>text</code> to annotate an image with text. Follow the text
3391coordinates with a string. If the string has embedded spaces, enclose it in
3392single or double quotes.</p>
3393
3394<p>For example, the following annotates the image with <code>Works like
3395magick!</code> for an image titled <code>bird.miff</code>. </p>
3396
3397<pre class="highlight"><code>-draw "text 100,100 'Works like magick!' "
3398</code></pre>
3399
3400<p>See the <a href="command-line-options.html#annotate">-annotate</a> option for another convenient way
3401to annotate an image with text.</p>
3402
3403<p>The <code>rotate</code> primitive rotates subsequent shape primitives and
3404text primitives about the origin of the main image.</p>
3405
3406<p>The <code>translate</code> primitive translates subsequent shape and text
3407primitives.</p>
3408
3409<p>The <code>scale</code> primitive scales them.</p>
3410
3411<p>The <code>skewX</code> and <code>skewY</code> primitives skew them with respect
3412to the origin of the main image or the region.</p>
3413
3414<p>The transformations modify the current affine matrix, which is initialized
3415from the initial affine matrix defined by the <a href="command-line-options.html#affine">-affine</a>
3416option. Transformations are cumulative within the <a href="command-line-options.html#draw">-draw</a>
3417option. The initial affine matrix is not affected; that matrix is only changed
3418by the appearance of another <a href="command-line-options.html#affine">-affine</a> option. If another
3419<a href="command-line-options.html#draw">-draw</a> option appears, the current affine matrix is
3420reinitialized from the initial affine matrix.</p>
3421
3422<p>Use the <code>color</code> primitive to change the color of a pixel to the
3423fill color (see <a href="command-line-options.html#fill">-fill</a>). Follow the pixel coordinate with
3424a method:</p>
3425
3426<pre class="highlight"><code>point
3427replace
3428floodfill
3429filltoborder
3430reset
3431</code></pre>
3432
3433<p>Consider the target pixel as that specified by your coordinate. The
3434<code>point</code> method recolors the target pixel. The <code>replace</code>
3435method recolors any pixel that matches the color of the target pixel.
3436<code>Floodfill</code> recolors any pixel that matches the color of the target
3437pixel and is a neighbor, whereas <code>filltoborder</code> recolors any neighbor
3438pixel that is not the border color. Finally, <code>reset</code> recolors all
3439pixels.</p>
3440
3441<p>Use <code>matte</code> to the change the pixel matte value to transparent.
3442Follow the pixel coordinate with a method (see the <code>color</code> primitive
3443for a description of methods). The <code>point</code> method changes the matte
3444value of the target pixel. The <code>replace</code> method changes the matte
3445value of any pixel that matches the color of the target pixel.
3446<code>Floodfill</code> changes the matte value of any pixel that matches the
3447color of the target pixel and is a neighbor, whereas <code>filltoborder</code>
3448changes the matte value of any neighbor pixel that is not the border color (<a
3449href="command-line-options.html#bordercolor">-bordercolor</a>). Finally <code>reset</code> changes the
3450matte value of all pixels.</p>
3451
3452<p>You can set the primitive color, font, and font bounding box color with <a
3453href="command-line-options.html#fill">-fill</a>, <a href="command-line-options.html#font">-font</a>, and <a href="command-line-options.html#box">-box</a>
3454respectively.  Options are processed in command line order so be sure to use
3455these options <var>before</var> the <a href="command-line-options.html#draw">-draw</a> option.</p>
3456
3457<p>Strings that begin with a number must be quoted (e.g. use '1.png' rather
3458than 1.png).</p>
3459
3460<p>Drawing primitives conform to the <a href="magick-vector-graphics.html" >Magick
3461Vector Graphics</a> format.</p>
3462
3463
3464<div style="margin: auto;">
3465  <h3><a class="anchor" id="duplicate"></a>-duplicate <var>count,indexes</var></h3>
3466</div>
3467
3468<p class="magick-description">duplicate an image one or more times.</p>
3469
3470<p>Specify the count and the image to duplicate by its index in the sequence.
3471The first image is index 0.  Negative indexes are relative to the end of the
3472sequence, for example, -1 represents the last image of the sequence.  Specify
3473a range of images with a dash (e.g. 0-4).  Separate indexes with a comma (e.g.
34740,2).  Use <code>+duplicate</code> to duplicate the last image in the current
3475image sequence.</p>
3476
3477<div style="margin: auto;">
3478  <h3><a class="anchor" id="edge"></a>-edge <var>radius</var></h3>
3479</div>
3480
3481<p class="magick-description">detect edges within an image.</p>
3482
3483<div style="margin: auto;">
3484  <h3><a class="anchor" id="emboss"></a>-emboss <var>radius</var></h3>
3485</div>
3486
3487<p class="magick-description">emboss an image.</p>
3488
3489<div style="margin: auto;">
3490  <h3><a class="anchor" id="encipher"></a>-encipher <var>filename</var></h3>
3491</div>
3492
3493<p class="magick-description">Encipher pixels for later deciphering by <a href="command-line-options.html#decipher">-decipher</a>.</p>
3494
3495<p>Get the passphrase from the file specified by <var>filename</var>.</p>
3496
3497<p>For more information, see the webpage, <a
3498href="../www/cipher.html">ImageMagick: Encipher or
3499Decipher an Image</a>.</p>
3500
3501
3502
3503<div style="margin: auto;">
3504  <h3><a class="anchor" id="encoding"></a>-encoding <var>type</var></h3>
3505</div>
3506
3507<p class="magick-description">specify the text encoding.</p>
3508
3509<p>Choose from</p>
3510
3511<pre class="highlight"><code>AdobeCustom     AdobeExpert
3512AdobeStandard   AppleRoman
3513BIG5            GB2312
3514Latin 2         None
3515SJIScode        Symbol
3516Unicode         Wansung
3517</code></pre>
3518
3519<div style="margin: auto;">
3520  <h3><a class="anchor" id="endian"></a>-endian <var>type</var></h3>
3521</div>
3522
3523<p class="magick-description">Specify endianness (<code>MSB</code> or <code>LSB</code>) of the image.</p>
3524
3525<p>To print a complete list of endian types, use the <a href="command-line-options.html#list">-list endian</a> option.</p>
3526
3527<p>Use <a href="command-line-options.html#endian">+endian</a> to revert to unspecified endianness.</p>
3528
3529
3530<div style="margin: auto;">
3531  <h3><a class="anchor" id="enhance"></a>-enhance</h3>
3532</div>
3533
3534<p class="magick-description">Apply a digital filter to enhance a noisy image.</p>
3535
3536
3537<div style="margin: auto;">
3538  <h3><a class="anchor" id="equalize"></a>-equalize</h3>
3539</div>
3540
3541<p class="magick-description">perform histogram equalization on the image channel-by-channel.</p>
3542
3543<p>To perform histogram equalization on all channels in concert, transform the
3544image into some other color space, such as HSL, OHTA, YIQ or YUV, then
3545equalize the appropriate intensity-like channel, then convert back to RGB.</p>
3546
3547<p>For example using HSL, we have: ... <code>-colorspace HSL -channel lightness
3548-equalize -colorspace RGB</code> ...</p>
3549
3550<p>For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal
3551components transformation that puts most of the information in the first
3552channel. Here we have ... <code>-colorspace OHTA -channel red -equalize
3553-colorspace RGB</code> ...</p>
3554
3555<div style="margin: auto;">
3556  <h3><a class="anchor" id="evaluate"></a>-evaluate <var>operator value</var></h3>
3557</div>
3558
3559<p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or logical expression.</p>
3560
3561<p>(See the <a href="command-line-options.html#function" >-function</a> operator for some
3562multi-parameter functions. See the <a href="command-line-options.html#fx" >-fx</a> operator if more
3563elaborate calculations are needed.)</p>
3564
3565<p>The behaviors of each <var>operator</var> are summarized in the
3566following list. For brevity, the numerical value of a "pixel" referred to
3567below is the value of the corresponding channel of that pixel, while
3568a "normalized pixel" is that number divided by the maximum
3569(installation-dependent) value <var>QuantumRange</var>. (If
3570normalized pixels are used, they are restored, following the other
3571calculations, to the full range by multiplying by <var>QuantumRange</var>.)</p>
3572
3573<table class="table table-sm table-striped">
3574  <col width="25%" />
3575  <col width="75%" />
3576  <thead>
3577  <tr>
3578  <th><var>operator</var></th>
3579  <th>Summary (see further below for details)</th>
3580  </tr>
3581  </thead>
3582  <tbody>
3583
3584    <tr><td>Abs </td>             <td>Add <var>value</var> to pixels and return absolute value. </td></tr>
3585    <tr><td>Add </td>             <td>Add <var>value</var> to pixels. </td></tr>
3586    <tr><td>AddModulus </td>      <td>Add <var>value</var> to pixels modulo <var>QuantumRange</var>.</td></tr>
3587    <tr><td>And  </td>            <td>Binary AND of pixels with <var>value</var>.</td></tr>
3588    <tr><td>Cos, Cosine </td>             <td>Apply cosine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3589    <tr><td>Divide  </td>         <td>Divide pixels by <var>value</var>.</td></tr>
3590    <tr><td>Exp  </td>            <td>base-e exponential function</td></tr>
3591    <tr><td>Exponential  </td>            <td>base-e exponential function</td></tr>
3592    <tr><td>LeftShift </td>       <td>Shift the pixel values left by <var>value</var> bits (i.e., multiply pixels by 2<sup><var>value</var></sup>).</td></tr>
3593    <tr><td>Log  </td>            <td>Apply scaled logarithm to normalized pixels.</td></tr>
3594    <tr><td>Max  </td>            <td>Set pixels to maximum of <var>value</var> and current pixel <var>value</var> (i.e. set any pixels currently less than <var>value</var> to <var>value</var>).</td></tr>
3595    <tr><td>Mean  </td>            <td>Add the <var>value</var> and divide by 2.</td></tr>
3596    <tr><td>Median  </td>          <td>Choose the median value from an image sequence.</td></tr>
3597    <tr><td>Min  </td>            <td>Set pixels to minimum of <var>value</var> and current pixel <var>value</var> (i.e. set any pixels currently greater than <var>value</var> to <var>value</var>).</td></tr>
3598    <tr><td>Multiply </td>        <td>Multiply pixels by <var>value</var>.</td></tr>
3599    <tr><td>Or  </td>             <td>Binary OR of pixels with <var>value</var>.</td></tr>
3600    <tr><td>Pow </td>             <td>Raise normalized pixels to the power <var>value</var>.</td></tr>
3601    <tr><td>RightShift </td>      <td>Shift the pixel values right by <var>value</var> bits (i.e., divide pixels by 2<sup><var>value</var></sup>).</td></tr>
3602    <tr><td>RMS</td>            <td>Square the pixel and add the <var>value</var>.</td></tr>
3603    <tr><td>RootMeanSquare</td>            <td>Square the pixel and add the <var>value</var>.</td></tr>
3604    <tr><td>Set </td>             <td>Set pixel equal to <var>value</var>.</td></tr>
3605    <tr><td>Sin, Sine </td>             <td>Apply sine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3606    <tr><td>Subtract </td>        <td>Subtract <var>value</var> from pixels.</td></tr>
3607    <tr><td>Xor </td>             <td>Binary XOR of pixels with <var>value.</var></td></tr>
3608
3609    <tr><td> </td><td> </td></tr>
3610
3611   <tr><td>Gaussian-noise</td><td> </td></tr>
3612   <tr><td>Impulse-noise</td><td> </td></tr>
3613   <tr><td>Laplacian-noise</td><td> </td></tr>
3614   <tr><td>Multiplicative-noise</td>      <td>(These are equivalent to the corresponding <a href="command-line-options.html#noise" >-noise</a> operators.)</td></tr>
3615   <tr><td>PoissonNoise</td><td> </td></tr>
3616   <tr><td>Uniform-noise</td><td> </td></tr>
3617
3618    <tr><td> </td><td> </td></tr>
3619
3620   <tr><td>Threshold </td>       <td>Threshold pixels larger than <var>value</var>.</td></tr>
3621   <tr><td>ThresholdBlack </td>  <td>Threshold pixels to zero values equal to or below <var>value</var>.</td></tr>
3622   <tr><td>ThresholdWhite </td>  <td>Threshold pixels to maximum values above <var>value</var>.  </td></tr>
3623 </tbody>
3624 </table>
3625
3626<p>The specified functions are applied only to each previously set <a
3627href="command-line-options.html#channel" >-channel</a> in the image. If necessary, the results of the
3628calculations are truncated (clipped) to fit in the interval [0, <var>QuantumRange</var>].  The transparency channel of the image is
3629represented as a 'alpha' values (0 = fully transparent), so, for example, a
3630<code>Divide</code> by 2 of the alpha channel will make the image
3631semi-transparent.  Append the percent symbol '<code>%</code>' to specify a value
3632as a percentage of the <var>QuantumRange</var>.</p>
3633
3634<p>To print a complete list of <a href="command-line-options.html#evaluate">-evaluate</a> operators, use
3635<a href="command-line-options.html#list">-list evaluate</a>.</p>
3636
3637<p>The results of the <code>Add</code>, <code>Subtract</code> and
3638<code>Multiply</code> methods can also be achieved using either the <a
3639href="command-line-options.html#level" >-level</a> or the <a href="command-line-options.html#level" >+level</a> operator, with
3640appropriate argument, to linearly modify the overall range of color values.
3641Please note, however, that <a href="command-line-options.html#level" >-level</a> treats transparency as
3642'matte' values (0 = opaque), while <a href="command-line-options.html#level" >-evaluate</a> works with
3643'alpha' values.</p>
3644
3645<p><code>AddModulus</code> has been added as of ImageMagick 6.4.8-4 and provides
3646addition modulo the <var>QuantumRange</var>. It is therefore
3647equivalent to <code>Add</code> unless the resulting pixel value is outside the
3648interval [0, <var>QuantumRange</var>]. </p>
3649
3650<p><code>Exp or Exponential</code> has been added as of ImageMagick 6.6.5-1 and
3651works on normalized pixel values. The <var>value</var> used with
3652<code>Exp</code> should be negative so as to produce a decaying exponential
3653function. Non-negative values will always produce results larger unity and
3654thus outside the interval [0, <var>QuantumRange</var>]. The
3655formula is expressed below. </p>
3656
3657<p class="text-center">
3658exp(<var>value</var> × <b><var>u</var></b>)
3659</p>
3660
3661<p> If the input image is squared, for example, using <a href="command-line-options.html#-function"
3662>-function polynomial "2 0 0"</a>, then a decaying Gaussian function will be
3663the result.</p>
3664
3665<p><code>Log</code> has been added as of ImageMagick 6.4.2-1 and works on
3666normalized pixel values. This a <var>scaled</var> log function. The <var>value</var> used with <code>Log</code> provides a <var>scaling
3667factor</var> that adjusts the curvature in the graph of the log function. The
3668formula applied to a normalized value <b><var>u</var></b> is below. </p>
3669
3670<p class="text-center">
3671log(<var>value</var> × <b><var>u</var></b> + 1) / log(<var>value</var> + 1)
3672</p>
3673
3674<p><code>Pow</code> has been added as of ImageMagick 6.4.1-9, and works on
3675normalized pixel values. Note that <code>Pow</code> is related to the <a
3676href="command-line-options.html#gamma" >-gamma</a> operator. For example, <b>-gamma 2</b> is equivalent
3677to <b>-evaluate pow 0.5</b>, i.e., a 'square root' function. The value used
3678with <a href="command-line-options.html#gamma" >-gamma</a> is simply the reciprocal of the value used
3679with <code>Pow</code>.</p>
3680
3681<p><code>Cosine</code> and <code>Sine</code> was added as of IM v6.4.8-8 and
3682converts the image values into a value according to a (co)sine wave function.
3683The  synonyms <code>Cos</code> and <code>Sin</code> may also be used.  The output
3684is biased 50% and normalized by 50% so as to fit in the respective color value
3685range.  The <var>value</var> scaling of the <var>period</var> of the
3686function (its frequency), and thus determines the number of 'waves' that will
3687be generated over the input color range.  For example, if the <var>value</var> is 1, the effective period is simply the <var>QuantumRange</var>; but if the <var>value</var> is 2,
3688then the effective period is the <var>half</var> the <var>QuantumRange</var>.</p>
3689
3690<p class="text-center">
36910.5 + 0.5 × cos(2 π <b><var>u</var></b> × <var>value</var>).
3692</p>
3693
3694<p>See also the <a href="command-line-options.html#function" >-function</a> operator, which is a
3695multi-value version of evaluate. </p>
3696
3697<div style="margin: auto;">
3698  <h3><a class="anchor" id="evaluate-sequence"></a>-evaluate-sequence <var>operator</var></h3>
3699</div>
3700
3701<p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or logical expression over a sequence of images.  Ensure all the images in the sequence are in the same colorspace, otherwise you may get unexpected results, e.g. add <a href="command-line-options.html#colorspace" >-colorspace sRGB</a> to your command-line.</p>
3702
3703<p>To print a complete list of <a
3704href="command-line-options.html#evaluate-sequence">-evaluate-sequence</a> operators, use <a
3705href="command-line-options.html#list">-list evaluate</a>.</p>
3706
3707<div style="margin: auto;">
3708  <h3><a class="anchor" id="extent"></a>-extent <var>geometry</var></h3>
3709</div>
3710
3711<p class="magick-description">Set the image size and offset.</p>
3712
3713<p>If the image is enlarged, unfilled areas are set to the background color.
3714To position the image, use offsets in the <var>geometry</var>
3715specification or precede with a <a href="command-line-options.html#gravity">-gravity</a> setting.  To
3716specify how to compose the image with the background, use <a href="command-line-options.html#compose"
3717>-compose</a>.</p>
3718
3719<p>This command reduces or expands a JPEG image to fit on an 800x600
3720display.  If the aspect ratio of the input image isn't exactly 4:3, then the
3721image is centered on an 800x600 black canvas: </p>
3722
3723<pre class="highlight"><code>convert input.jpg -resize 800x600 -background black -compose Copy \
3724  -gravity center -extent 800x600 -quality 92 output.jpg
3725</code></pre>
3726
3727<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3728
3729<div style="margin: auto;">
3730  <h3><a class="anchor" id="extract"></a>-extract <var>geometry</var></h3>
3731</div>
3732
3733<p class="magick-description">Extract the specified area from image.</p>
3734
3735<p>This option is most useful for extracting a subregion of a very large raw
3736image.  Note that these two commands are equivalent:</p>
3737
3738<pre class="highlight"><code>convert -size 16000x16000 -depth 8 -extract 640x480+1280+960 \
3739  image.rgb image.png",
3740convert -size 16000x16000 -depth 8 'image.rgb[640x480+1280+960]' \
3741  image.rgb image.png"
3742</code></pre>
3743
3744<p>If you omit the offsets, as in</p>
3745
3746<pre class="highlight"><code>convert -size 16000x16000 -depth 8 -extract 640x480 \
3747  image.rgb image.png
3748</code></pre>
3749
3750<p>the image is <var>resized</var> to the specified dimensions instead,
3751equivalent to:</p>
3752
3753<pre class="highlight"><code>convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png
3754</code></pre>
3755
3756<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3757
3758<div style="margin: auto;">
3759  <h3><a class="anchor" id="family"></a>-family <var>fontFamily</var></h3>
3760</div>
3761
3762<p class="magick-description">Set a font family for text.</p>
3763
3764<p>This setting suggests a font family that ImageMagick should try to use for
3765rendering text. If the family can be found it is used; if not, a default font
3766(e.g., "Arial") or a family known to be similar is substituted (e.g.,
3767"Courier" might be used if "System" is requested but not found).  </p>
3768
3769<p>For other settings that affect fonts, see the options <a
3770href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a
3771href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>.  </p>
3772
3773<div style="margin: auto;">
3774  <h3><a class="anchor" id="features"></a>-features <var>distance</var></h3>
3775</div>
3776
3777<p class="magick-description">display (co-occurrence matrix) texture measure features for each channel in the image in each of four directions (horizontal, vertical, left and right diagonals) for the specified distance.</p>
3778
3779<pre class="highlight"><code>Angular Second Moment       Sum Entropy
3780Contrast                    Entropy
3781Correlation                 Difference Variance
3782Sum of Squares Variance     Difference Entropy
3783Inverse Difference Moment   Information Measure of Correlation 1
3784Sum Average                 Information Measure of Correlation 2
3785Sum Variance                Maximum Correlation Coefficient
3786</code></pre>
3787
3788<div style="margin: auto;">
3789  <h3><a class="anchor" id="fft"></a>-fft</h3>
3790</div>
3791
3792<p class="magick-description">implements the forward discrete Fourier transform (DFT).</p>
3793
3794<p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
3795users in ImageMagick 6.6.0-9). It transforms an image from the normal
3796(spatial) domain to the frequency domain. In the frequency domain, an image is
3797represented as a superposition of complex sinusoidal waves of varying
3798amplitudes. The image x and y coordinates are the possible frequencies along
3799the x and y directions, respectively, and the pixel intensity values are
3800complex numbers that correspond to the sinusoidal wave amplitudes. See for
3801example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier
3802Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier
3803Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier
3804Transform</a>.</p>
3805
3806<p>A single image name is provided as output for this option. However, the
3807output result will have two components. It is either a two-frame image or two
3808separate images, depending upon whether the image format specified supports
3809multi-frame images. The reason that we get a dual output result is because the
3810frequency domain represents an image using complex numbers, which cannot be
3811visualized directly. Therefore, the complex values are automagically separated
3812into a two-component image representation. The first component is the
3813magnitude of the complex number and the second is the phase of the complex
3814number. See for example, <a
3815href="http://en.wikipedia.org/wiki/Complex_numbers">Complex Numbers</a>.</p>
3816
3817<p>The magnitude and phase component images must be specified using image
3818formats that do not limit the color or compress the image. Thus, MIFF, TIF,
3819PFM, EXR and PNG are the recommended image formats to use. All of these
3820formats, except PNG support multi-frame images. So for example,</p>
3821
3822<pre class="highlight"><code>convert image.png -fft fft_image.miff
3823</code></pre>
3824
3825<p>generates a magnitude image as <code>fft_image.miff[0]</code> and a phase
3826image as <code>fft_image.miff[1]</code>. Similarly,</p>
3827
3828<pre class="highlight"><code>convert image.png -fft fft_image.png
3829</code></pre>
3830
3831<p>generates a magnitude image as <code>fft_image-0.png</code> and a phase image
3832as <code>fft_image-1.png</code>. If you prefer this representation, then you can
3833force any of the other formats to produce two output images by including <a
3834href="command-line-options.html#adjoin">+adjoin</a> following -fft in the command line.</p>
3835
3836<p>The input image can be any size, but if not square and even-dimensioned, it
3837is padded automagically to the larger of the width or height of the input
3838image and to an even number of pixels. The padding will occur at the bottom
3839and/or right sides of the input image. The resulting output magnitude and
3840phase images is square at this size. The kind of padding relies on the <a
3841href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting.</p>
3842
3843<p>Both output components will have dynamic ranges that fit within
3844[0, <var>QuantumRange</var>], so that HDRI need not be enabled.
3845Phase values nominally range from 0 to 2*π, but is scaled to span the full
3846dynamic range.  (The first few releases had non-HDRI scaled but HDRI not
3847scaled). The magnitude image is not scaled and thus generally will contain
3848very small values. As such, the image normally will appear totally black. In
3849order to view any detail, the magnitude image typically is enhanced with a log
3850function into what is usually called the spectrum. A log function is used to
3851enhance the darker values more in comparison to the lighter values. This can
3852be done, for example, as follows:</p>
3853
3854<pre class="highlight"><code>convert fft_image.miff[0] -contrast-stretch 0 \
3855  -evaluate log 1000 fft_image_spectrum.png"
3856</code></pre>
3857
3858<p>where either <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> 0 or <a
3859href="command-line-options.html#auto-level">-auto-level</a> is used to scale the image to full dynamic
3860range, first. The argument to the <a href="command-line-options.html#evaluate">-evaluate</a> log
3861typically is specified between 100 and 10,000, depending upon the amount of
3862detail that one wants to bring out in the spectrum. Larger values produce more
3863visible detail. Too much detail, however, may hide the important features.</p>
3864
3865<p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
3866use <a href="command-line-options.html#fft">-fft</a>.</p>
3867
3868<p>Use <a href="command-line-options.html#fft">+fft</a> to produce two output images that are the real
3869and imaginary components of the complex valued Fourier transform.</p>
3870
3871<p>However, as the real and imaginary components can contain negative values,
3872this requires that IM be configured with HDRI enabled. In this case, you must
3873use either MIFF, TIF, PFM or MPC formats for the real and imaginary component
3874results, since they are formats that preserve both negative and fractional
3875values without clipping them or truncating the fractional part. With either
3876MIFF or TIF, one should add <code>-define quantum:format=32</code>, to allow those image
3877types to work properly in HDRI mode without clipping.</p>
3878
3879<p>The real and imaginary component images resulting from <a
3880href="command-line-options.html#fft">+fft</a> are also square, even dimensioned images due to the same
3881padding that was discussed above for the magnitude and phase component
3882images.</p>
3883
3884<p>See the discussion on HDRI implementations of ImageMagick on the page <a
3885href="high-dynamic-range.html" >High Dynamic-Range Images</a>. For more
3886about HDRI go the ImageMagick <a
3887href="../Usage/basics/#hdri" >Usage</a> pages, <a
3888href="http://www.fmwconcepts.com/imagemagick/fourier_transforms/fourier.html"
3889>Fred's Fourier Processing With ImageMagick page</a> or this <a
3890 href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging" >Wikipedia</a>
3891 entry.  </p>
3892
3893<p>By default the FFT is normalized (and the IFT is not). Use "<code><a href="command-line-options.html#define" >-define</a> fourier:normalize=forward</code> to explicitly normalize the FFT and unnormalize the IFT.</p>
3894
3895
3896<div style="margin: auto;">
3897  <h3><a class="anchor" id="fill"></a>-fill <var>color</var></h3>
3898</div>
3899
3900<p class="magick-description">color to use when filling a graphic primitive.</p>
3901
3902<p>This option accepts a color name, a hex color, or a numerical RGB, RGBA,
3903HSL, HSLA, CMYK, or CMYKA specification.  See <a href="../www/color.html" >Color Names</a> for
3904a description of how to properly specify the color argument.</p>
3905
3906<p>Enclose the color specification in quotation marks to prevent the "#" or
3907the parentheses from being interpreted by your shell.</p>
3908
3909<p>For example,</p>
3910
3911<pre class="highlight"><code>-fill blue
3912-fill "#ddddff"
3913-fill "rgb(255,255,255)"
3914</code></pre>
3915
3916<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
3917
3918<p>To print a complete list of color names, use the <a href="command-line-options.html#list">-list color</a> option.</p>
3919
3920<div style="margin: auto;">
3921  <h3><a class="anchor" id="filter"></a>-filter <var>type</var></h3>
3922</div>
3923
3924<p class="magick-description">Use this <var>type</var> of filter when resizing or distorting an image.</p>
3925
3926<p>Use this option to affect the resizing operation of an image during
3927operations such as <a href="command-line-options.html#resize">-resize</a> and <a href="command-line-options.html#distort"
3928>-distort</a>. For example you can use a simple resize filter such as:</p>
3929
3930<pre class="highlight"><code>Point       Hermite       Cubic
3931Box         Gaussian      Catrom
3932Triangle    Quadratic     Mitchell
3933CubicSpline
3934</code></pre>
3935
3936<p>Use <code>-define filter:lobes={2,3,4}</code> to specify the support size for filtering for the <code>CubicSpline</code> filter.</p>
3937
3938<p>The <code>Bessel</code> and <code>Sinc</code> filter is also provided (as well
3939as a faster <code>SincFast</code> equivalent form).  However these filters are
3940generally useless on their own as they are infinite filters that are being
3941clipped to the filters support size. Their direct use is not recommended
3942except via expert settings (see below). </p>
3943
3944<p>Instead these special filter functions are typically windowed by a windowing
3945function that the <a href="command-line-options.html#filter" >-filter</a> setting defines.   That is
3946using these functions will define a 'Windowed' filter, appropriate to the
3947operator involved.  Windowed filters include: </p>
3948
3949<pre class="highlight"><code>Lanczos       Hamming       Parzen
3950Blackman      Kaiser        Welsh
3951Hanning       Bartlett      Bohman
3952</code></pre>
3953
3954<p>Also one special self-windowing filter is also provided
3955<code>Lagrange</code>, which will automagically re-adjust its function depending
3956on the current 'support' or 'lobes' expert settings (see below).</p>
3957
3958<p>If you do not select a filter with this option, the filter defaults to
3959<code>Mitchell</code> for a colormapped image, an image with a matte channel, or
3960if the image is enlarged.  Otherwise the filter default to
3961<code>Lanczos</code>.</p>
3962
3963<p>To print a complete list of resize filters, use the <a href="command-line-options.html#list">-list
3964filter</a> option.</p>
3965
3966<p>You can modify how the filter behaves as it scales your image through the
3967use of these expert settings (see also <a href="command-line-options.html#define" >-define</a> and <a
3968href="command-line-options.html#set" >-set</a>):-</p>
3969
3970<table class="table table-sm table-striped">
3971  <tr>
3972    <td>-define filter:blur=<var>factor</var></td>
3973    <td>Scale the X axis of the filter (and its window). Use &gt; 1.0 for
3974    blurry or &lt; 1.0 for sharp. This should only be used with Gaussian and
3975    Gaussian-like filters simple filters, or you may not get the expected
3976    results. </td>
3977  </tr>
3978
3979  <tr>
3980    <td>-define filter:support=<var>radius</var></td>
3981    <td>Set the filter support radius. Defines how large the filter should be and
3982    thus directly defines how slow the filtered resampling process is. All
3983    filters have a default 'preferred' support size. Some filters like
3984    <code>Lagrange</code> and windowed filters adjust themselves depending on
3985    this value.  With simple filters this value either does nothing (but slow
3986    the resampling), or will clip the filter function in a detrimental way.
3987    </td>
3988  </tr>
3989
3990  <tr>
3991    <td>-define filter:lobes=<var>count</var></td>
3992    <td>Set the number of lobes to use for the Sinc/Bessel filter. This an
3993    alternative way of specifying the 'support' range of the filter, that is
3994    designed to be more suited to windowed filters, especially when used for
3995    image distorts.</td>
3996  </tr>
3997
3998  <tr>
3999    <td>-define filter:sigma=<var>value</var></td>
4000    <td>The 'sigma' value used to define the <code>Gaussian</code> filter.  Default
4001    sigma value is '<code>0.5</code>'.  It only affects <code>Gaussian</code> but
4002    does not shrink (but may enlarge) the filter's 'support'.  It can be used
4003    to generate very small blurs but without the filter 'missing' pixels due
4004    to using a small support setting. A larger value of '<code>0.707</code>'
4005    (a value of '1/sqrt(2)') is another common setting. </td>
4006  </tr>
4007
4008  <tr>
4009    <td>-define filter:b=<var>b-spline_factor</var></td>
4010  </tr>
4011
4012  <tr>
4013    <td>-define filter:c=<var>keys_alpha_factor</var></td>
4014    <td>Redefine the values used for cubic filters such as <code>Cubic</code>,
4015    <code>Catrom</code>, <code>Mitchel</code>, and <code>Hermite</code>, as well as
4016    the <code>Parzen</code> cubic windowing function. If only one of the values
4017    are defined, the other is set so as to generate a 'Cubic-Keys' filter.
4018    The values meaning was defined by a research paper by
4019    Mitchell-Netravali.</td>
4020  </tr>
4021
4022  <tr>
4023    <td>-define filter:kaiser-beta=<var>value</var></td>
4024    <td>The 'alpha' value used to as part of the Kaiser Windowing function.
4025    Default value is '6.5'.  It only affects Kaiser windowing function, and
4026    does not affect any other attributes.
4027    Before ImageMagick v6.7.6-10, this option was known as "filter:alpha", (an
4028    inheritance from the very old "zoom" program). It was changed to bring the
4029    function in line with more modern academic research usage, and better
4030    assign it be more definitive.  </td>
4031  </tr>
4032
4033  <tr>
4034    <td>-define filter:kaiser-alpha=<var>value</var></td>
4035    <td>This value when multiplied by 'PI' is equivalent to "kaiser-beta", and
4036    will override that setting.  It only affects Kaiser windowing function,
4037    and does not affect any other attributes. </td>
4038  </tr>
4039
4040  <tr>
4041    <td>-define filter:filter=<var>filter_function</var></td>
4042    <td>Use this function directly as the weighting filter.  This will allow
4043    you to directly use a windowing function such as <code>Blackman</code>,
4044    as a resampling filter, rather than as its normal usage as a windowing
4045    function.  If defined, no windowing function also defined, the window function is set
4046    to <code>Box</code>). Directly specifying <code>Sinc</code> or <code>Jinc</code>
4047    as a filter will also do this. </td>
4048  </tr>
4049
4050  <tr>
4051    <td>-define filter:window=<var>filter_function</var></td>
4052    <td>The IIR (infinite impulse response) filters <code>Sinc</code> and
4053    <code>Jinc</code> are windowed (brought down to zero over the defined
4054    support range) with the given filter. This allows you to specify a filter
4055    function to be used as a windowing function for these IIR filters.
4056    Many of the defined filters are actually windowing functions for these IIR
4057    filters.  A typical choices is <code>Box</code>, (which effectively turns
4058    off the windowing function).  </td>
4059  </tr>
4060
4061  <tr>
4062    <td>-define filter:win-support=<var>radius</var></td>
4063    <td>Scale windowing function to this size instead.  This causes the windowing
4064    (or self-windowing Lagrange filter) to act is if the support window is
4065    larger than what is actually supplied to the calling operator.  The filter
4066    however is still clipped to the real support size given.  If unset this
4067    will equal the normal filter support size. </td>
4068  </tr>
4069
4070  <tr>
4071    <td>-define filter:verbose=<var>1</var></td>
4072    <td>This causes IM to print information on the final internal filter
4073    selection to standard output.  This includes a commented header on the
4074    filter settings being used, and data allowing the filter weights to be
4075    easily graphed.  Note however that some filters are internally defined in terms of other filters.  The <code>Lanczos</code> filter for example is defined in terms of
4076    a <code>SincFast</code> windowed <code>SincFast</code> filter, while
4077    <code>Mitchell</code> is defined as a general <code>Cubic</code> family filter
4078    with specific 'B' and 'C' settings. </td>
4079  </tr>
4080
4081</table>
4082
4083<p>For example, to get a 8 lobe jinc windowed sinc filter (Genseng filter?):</p>
4084
4085<pre class="highlight"><code>convert image.png \
4086  -filter sinc \
4087  -set filter:window=jinc \
4088  -set filter:lobes=8 \
4089  -resize 150% image.jpg"
4090</code></pre>
4091
4092<p>Or a raw un-windowed Sinc filter with 4 lobes:</p>
4093
4094<pre class="highlight"><code>convert image.png \
4095  -set filter:filter=sinc \
4096  -set filter:lobes=4 \
4097  -resize 150% image.jpg"
4098</code></pre>
4099
4100<p>To extract the data for a raw windowing function, combine it with
4101a '<code>Box</code>' filter.  For example the '<code>Welch</code> parabolic
4102windowing function. </p>
4103
4104<pre class="highlight"><code>convert null: -define filter:filter=Box \
4105  -define filter:window=Welch \
4106  -define filter:support=1.0 \
4107  -define filter:verbose=1 \
4108  -resize 2 null: > window_welch.dat
4109gnuplot
4110  set grid
4111  plot \"window_welch.dat\" with lines
4112</code></pre>
4113
4114<p>Note that the use of expert options is provided for image processing experts
4115who have studied and understand how resize filters work. Without this
4116knowledge, and an understanding of the definition of the actual filters
4117involved, using expert settings are more likely to be detrimental to your image
4118resizing.</p>
4119
4120
4121<div style="margin: auto;">
4122  <h3><a class="anchor" id="flatten"></a>-flatten</h3>
4123</div>
4124
4125<p class="magick-description">This is a simple alias for the <a href="command-line-options.html#layers" >-layers</a> method "flatten".</p>
4126
4127
4128<div style="margin: auto;">
4129  <h3><a class="anchor" id="flip"></a>-flip</h3>
4130</div>
4131
4132<p class="magick-description">create a <var>mirror image</var></p>
4133
4134<p>reflect the scanlines in the vertical direction. The image will be mirrored
4135upside-down. </p>
4136
4137
4138<div style="margin: auto;">
4139  <h3><a class="anchor" id="floodfill"></a>-floodfill {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var> <var>color</var></h3>
4140</div>
4141
4142<p class="magick-description">floodfill the image with color at the specified offset.</p>
4143
4144<p>Flood fill starts from the given 'seed point' which is not gravity affected.
4145Any color that matches within <a href="command-line-options.html#fuzz" >-fuzz</a> color distance of the
4146given <var>color</var>  argument, connected to that 'seed point'
4147will be replaced with the current <a href="command-line-options.html#fill" >-fill</a> color. </p>
4148
4149<p>Note that if the pixel at the 'seed point' does not itself match the given
4150<var>color</var> (according to <a href="command-line-options.html#fuzz" >-fuzz</a>), then no
4151action will be taken. </p>
4152
4153<p>This operator works more like the <a href="command-line-options.html#opaque" >-opaque</a> option, than
4154a more general flood fill that reads the matching color directly at the 'seed
4155point'. For this form of flood fill, look at <a href="command-line-options.html#draw" >-draw</a>  and
4156its 'color floodfill' drawing method.  </p>
4157
4158
4159<div style="margin: auto;">
4160  <h3><a class="anchor" id="flop"></a>-flop</h3>
4161</div>
4162
4163<p class="magick-description">create a <var>mirror image</var>.</p>
4164
4165<p>Reflect the scanlines in the horizontal direction, just like the image in
4166a vertical mirror. </p>
4167
4168
4169<div style="margin: auto;">
4170  <h3><a class="anchor" id="font"></a>-font <var>name</var></h3>
4171</div>
4172
4173<p class="magick-description">set the font to use when annotating images with text, or creating labels.</p>
4174
4175<p>To print a complete list of fonts, use the <a href="command-line-options.html#list">-list font</a>
4176option (for versions prior to 6.3.6, use 'type' instead of 'font').</p>
4177
4178<p>In addition to the fonts specified by the above pre-defined list, you can
4179also specify a font from a specific source.  For example <code>Arial.ttf</code>
4180is a TrueType font file, <code>ps:helvetica</code> is PostScript font, and
4181<code>x:fixed</code> is X11 font.</p>
4182
4183<p>For other settings that affect fonts, see the options <a
4184href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a
4185href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
4186
4187
4188<div style="margin: auto;">
4189  <h3><a class="anchor" id="foreground"></a>-foreground <var>color</var></h3>
4190</div>
4191
4192<p class="magick-description">Define the foreground color for menus.", "display</p>
4193
4194<p>The color is specified using the format described under the <a
4195href="command-line-options.html#fill">-fill</a> option.</p>
4196
4197<p>The default foreground color is black.</p>
4198
4199<div style="margin: auto;">
4200  <h3><a class="anchor" id="format"></a>-format <var>type</var></h3>
4201</div>
4202
4203<p class="magick-description">the image format type.</p>
4204
4205<p>When used with the <code>mogrify</code> utility, this option converts any
4206image to the image <a href="formats.html">format</a> you specify.
4207For a list of image format types supported by ImageMagick, use <a
4208href="command-line-options.html#list">-list format</a>.</p>
4209
4210<p>By default the file is written to its original name. However, if the
4211filename extension matches a supported format, the extension is replaced with
4212the image format type specified with <a href="command-line-options.html#format">-format</a>. For
4213example, if you specify <var>tiff</var> as the format type and the
4214input image filename is <var>image.gif</var>, the output image
4215filename becomes <var>image.tiff</var>.</p>
4216
4217<div style="margin: auto;">
4218  <h3><a class="anchor" id="format_identify_"></a>-format <var>string</var></h3>
4219</div>
4220
4221<p class="magick-description">output formatted image characteristics.</p>
4222
4223<p>See <a href="../www/escape.html">Format and Print Image
4224Properties</a> for an explanation on how to specify the argument to this
4225option.</p>
4226
4227<div style="margin: auto;">
4228  <h3><a class="anchor" id="frame"></a>-frame <var>geometry</var></h3>
4229</div>
4230
4231<p class="magick-description">Surround the image with a border or beveled frame.</p>
4232
4233<p>The color of the border is specified with the <a href="command-line-options.html#mattecolor"
4234>-mattecolor</a> command line option. </p>
4235
4236<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <var>size</var> portion of the <var>geometry</var> argument indicates the amount of extra width and
4237height that is added to the dimensions of the image. If no offsets are given
4238in the <var>geometry</var> argument, then the border added is
4239a solid color.  Offsets <var>x</var> and <var>y</var>, if present, specify that
4240the width and height of the border is partitioned to form an outer bevel of
4241thickness <var>x</var> pixels and an inner bevel of thickness
4242<var>y</var> pixels. Negative offsets make no sense as frame arguments.
4243</p>
4244
4245<p>The <a href="command-line-options.html#frame">-frame</a> option is affected by the current <a
4246href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
4247'<code>Over</code>' composition method.  It generates an image of the appropriate
4248size with the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting, and then
4249draws the frame of four distinct colors close to the current <a
4250href="command-line-options.html#mattecolor">-mattecolor</a>.  The original image is then overlaid onto
4251center of this image.  This means that with the default compose method of
4252'<code>Over</code>' any transparent parts may be replaced by the current <a
4253href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
4254
4255<p>The image composition is not
4256affected by the <a href="command-line-options.html#gravity">-gravity</a> option.</p>
4257
4258
4259<div style="margin: auto;">
4260  <h3><a class="anchor" id="frame_import_"></a>-frame</h3>
4261</div>
4262
4263<p class="magick-description">include the X window frame in the imported image. </p>
4264<div style="margin: auto;">
4265  <h3><a class="anchor" id="function"></a>-function <var>function</var> <var>parameters</var></h3>
4266</div>
4267
4268<p class="magick-description">Apply a function to channel values.</p>
4269
4270<p>This operator performs calculations based on the given arguments to modify
4271each of the color values for each previously set <a
4272href="command-line-options.html#channel">-channel</a> in the image. See <a
4273href="command-line-options.html#evaluate">-evaluate</a> for details concerning how the results of the
4274calculations are handled.</p>
4275
4276<p>This is can be considered a multi-argument version of the <a
4277href="command-line-options.html#evaluate">-evaluate</a> operator. (Added in
4278ImageMagick 6.4.8−8.)</p>
4279
4280<p>Here,  <var>parameters</var> is a comma-separated list of
4281numerical values. The number of values varies depending on which <var>function</var> is selected. Choose the <var>function</var> from:</p>
4282
4283<pre class="highlight"><code>Polynomial
4284Sinusoid
4285Arcsin
4286Arctan
4287</code></pre>
4288
4289<p>To print a complete list of <a href="command-line-options.html#function">-function</a> operators,
4290use <a href="command-line-options.html#list">-list function</a>. Descriptions follow.</p>
4291
4292<dl class="row">
4293  <dt class="col-md-4">Polynomial</dt>
4294  <dd class="col-md-8"><p>The <code>Polynomial</code> function takes an arbitrary number of parameters,
4295these being the coefficients of a polynomial, in decreasing order of degree.
4296That is, entering</p>
4297
4298<pre class="highlight"><code>-function Polynomial <var>a</var><sub><var>n</var></sub>,<var>a</var><sub><var>n</var>-1</sub>,...<var>a</var><sub>1</sub>,<var>a</var><sub>0</sub>
4299</code></pre>
4300
4301<p>will invoke a polynomial function given by</p>
4302
4303<pre class="highlight"><code><var>a</var><sub><var>n</var></sub> <b><var>u</var></b><sup><var>n</var></sup> + <var>a</var><sub><var>n</var>-1</sub> <b><var>u</var></b><sup><var>n</var>-1</sup> + ··· <var>a</var><sub>1</sub> <b><var>u</var></b> + <var>a</var><sub>0</sub>,
4304</code></pre>
4305
4306<p>where <b><var>u</var></b> is pixel's original normalized channel value.</p>
4307
4308<p>The <code>Polynomial</code> function can be used in place of <code>Set</code>
4309(the <var>constant</var> polynomial) and <code>Add</code>, <code>Divide</code>,
4310<code>Multiply</code>, and <code>Subtract</code> (some <var>linear</var>
4311polynomials) of the <a href="command-line-options.html#evaluate">-evaluate</a> operator. The <a
4312href="command-line-options.html#level">-level</a> operator also affects channels linearly. Some
4313correspondences follow.</p>
4314
4315<table class="table table-sm table-striped">
4316  <tr>
4317        <td>-evaluate Set <var>value</var> </td>
4318        <td>-function Polynomial <var>value</var></td>
4319        <td>(Constant functions; set <var>value</var>×100% gray when channels are RGB.)</td>
4320  </tr>
4321  <tr>
4322        <td>-evaluate Add <var>value</var> </td>
4323        <td>-function Polynomial 1,<var>value</var></td>
4324  </tr>
4325  <tr>
4326        <td>-evaluate Subtract <var>value</var> </td>
4327        <td>-function Polynomial 1,−<var>value</var></td>
4328  </tr>
4329  <tr>
4330        <td>-evaluate Multiply <var>value</var> </td>
4331        <td>-function Polynomial <var>value</var>,0</td>
4332  </tr>
4333  <tr>
4334        <td>+level  black% x white%</td>
4335        <td>-function Polynomial  A,B</td>
4336        <td>(Reduce contrast. Here, A=(white-black)/100 and  B=black/100.)</td>
4337  </tr>
4338</table>
4339
4340<p>The <code>Polynomial</code> function gives great versatility, since
4341polynomials can be used to fit any continuous curve to any degree of accuracy
4342desired.</p>
4343
4344</dd>
4345<dt class="col-md-4">Sinusoid</dt>
4346<dd class="col-md-8">
4347<p>The <code>Sinusoid</code> function can be used to vary the channel values
4348sinusoidally by setting frequency, phase shift, amplitude, and a bias. These
4349values are given as one to four parameters, as follows,</p>
4350
4351<pre class="highlight"><code>-function <code>Sinusoid</code> <var>freq</var>,[<var>phase</var>,[<var>amp</var>,[<var>bias</var>]]]
4352</code></pre>
4353
4354<p>where <var>phase</var> is in degrees. (The domain [0,1] of the function
4355corresponds to 0 through <var>freq</var>×360 degrees.)
4356The result is that if a pixel's normalized channel value is originally
4357<b><var>u</var></b>, its resulting normalized value is given by </p>
4358
4359<pre class="highlight"><code><var>amp</var> * sin(2*π* (<var>freq</var> * <b><var>u</var></b> + <var>phase</var> / 360)) + <var>bias</var>
4360</code></pre>
4361
4362<p> For example, the following generates a curve that starts and ends at 0.9
4363(when <b><var>u</var></b>=0 and 1, resp.), oscillating three times between
4364.7−.2=.5 and .7+.2=.9. </p>
4365
4366<pre class="highlight"><code>-function Sinusoid 3,-90,.2,.7
4367</code></pre>
4368
4369<p>The default values of <var>amp</var> and <var>bias</var> are both .5. The default for <var>phase</var>
4370is 0.</p>
4371
4372<p>The <code>Sinusoid</code> function generalizes <code>Sin</code> and
4373<code>Cos</code> of the <a href="command-line-options.html#evaluate">-evaluate</a> operator by allowing
4374varying amplitude, phase and bias. The correspondence is as follows.</p>
4375
4376<table class="table table-sm table-striped">
4377  <tr>
4378        <td>-evaluate Sin <var>freq</var> </td>
4379        <td>-function Sinusoid <var>freq</var>,0 </td>
4380  </tr>
4381  <tr>
4382        <td>-evaluate Cos <var>freq</var> </td>
4383        <td>-function Sinusoid <var>freq</var>,90 </td>
4384  </tr>
4385</table>
4386  </dd>
4387<dt class="col-md-4">ArcSin</dt>
4388<dd class="col-md-8">
4389<p>The <code>ArcSin</code> function generates the inverse curve of a Sinusoid,
4390and can be used to generate cylindrical distortion and displacement maps.
4391The curve can be adjusted relative to both the input values and output range
4392of values.</p>
4393
4394<pre class="highlight"><code>-function <code>ArcSin</code> <var>width</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
4395</code></pre>
4396
4397<p>with all values given in terms of normalized color values (0.0 for black,
43981.0 for white). Defaulting to values covering the full range from 0.0 to 1.0
4399for bout input (<var>width</var>), and output (<var>width</var>) values. '<code>1.0,0.5,1.0,0.5</code>' </p>
4400
4401<pre class="highlight"><code><var>range</var>/π * asin( 2/<var>width</var> * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
4402</code></pre>
4403
4404</dd>
4405<dt class="col-md-4">ArcTan</dt>
4406<dd class="col-md-8">
4407<p>The <code>ArcTan</code> function generates a curve that smooth crosses from
4408limit values at infinities, though a center using the given slope value.
4409All these values can be adjusted via the arguments.</p>
4410
4411<pre class="highlight"><code>-function <code>ArcTan</code> <var>slope</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
4412</code></pre>
4413
4414<p>Defaulting to '<code>1.0,0.5,1.0,0.5</code>'.
4415</p>
4416
4417<pre class="highlight"><code><var>range</var>/π * atan( <var>slope</var>*π * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
4418</code></pre>
4419  </dd>
4420</dl>
4421
4422
4423
4424<div style="margin: auto;">
4425  <h3><a class="anchor" id="fuzz"></a>-fuzz <var>distance</var>{<var>%</var>}</h3>
4426</div>
4427
4428<p class="magick-description">Colors within this <var>distance</var> are considered equal.</p>
4429
4430<p>A number of algorithms search for a target color. By default the color must
4431be exact. Use this option to match colors that are close to the target color
4432in RGB space. For example, if you want to automagically trim the edges of an
4433image with <a href="command-line-options.html#trim">-trim</a> but the image was scanned and the target
4434background color may differ by a small amount. This option can account for
4435these differences.</p>
4436
4437<p>The <var>distance</var> can be in absolute intensity units or, by
4438appending <code>%</code> as a percentage of the maximum possible intensity (255,
443965535, or 4294967295).</p>
4440
4441<p>Use <a href="command-line-options.html#fuzz" >+fuzz</a> to reset the fuzz value to 0.</p>
4442
4443
4444<div style="margin: auto;">
4445  <h3><a class="anchor" id="fx"></a>-fx <var>expression</var></h3>
4446</div>
4447
4448<p class="magick-description">apply a mathematical expression to an image or image channels.</p>
4449
4450<p>If the first character of <var>expression</var> is <code>@</code>,
4451the expression is read from a file titled by the remaining characters in the
4452string.</p>
4453
4454<p>See <a href="../www/fx.html">FX,
4455The Special Effects Image Operator</a> for a detailed discussion of this
4456option.</p>
4457
4458
4459<div style="margin: auto;">
4460  <h3><a class="anchor" id="gamma"></a>-gamma <var>value</var></h3>
4461</div>
4462
4463<p class="magick-description">level of gamma correction.</p>
4464
4465<p>The same color image displayed on two different workstations may look
4466different due to differences in the display monitor. Use gamma correction to
4467adjust for this color difference.  Reasonable values extend from
4468<code>0.8</code> to <code>2.3</code>. Gamma less than 1.0 darkens the image and
4469gamma greater than 1.0 lightens it. Large adjustments to image gamma may
4470result in the loss of some image information if the pixel quantum size is only
4471eight bits (quantum range 0 to 255).</p>
4472
4473<p>Gamma adjusts the image's channel values pixel-by-pixel according to
4474a power law, namely, pow(pixel,1/gamma) or pixel^(1/gamma), where pixel is the
4475normalized or 0 to 1 color value. For example, using a value of gamma=2 is the
4476same as taking the square root of the image.</p>
4477
4478<p>Use <a href="command-line-options.html#gamma">+gamma <var>value</var></a> to set the
4479image gamma level without actually adjusting the image pixels. This option
4480is useful if the image is of a known gamma but not set as an image attribute
4481(e.g. PNG images).  Write the "file gamma" which is the reciprocal of the
4482display gamma; e.g., if your image is sRGB and you want to write a PNG gAMA
4483chunk, use</p>
4484
4485<pre class="highlight"><code>convert input.png +gamma .45455 output.png
4486</code></pre>
4487
4488<p>(0.45455 is 1/2.2)</p>
4489
4490<p>Note that gamma adjustments are also available via the <a href="command-line-options.html#level">-level</a> operator.</p>
4491
4492<div style="margin: auto;">
4493  <h3><a class="anchor" id="gaussian-blur"></a>-gaussian-blur <var>radius</var><br />-gaussian-blur <var>radius</var>x<var>sigma</var></h3>
4494</div>
4495
4496<p class="magick-description">Blur the image with a Gaussian operator.</p>
4497
4498<p>Convolve the image with a Gaussian or normal distribution using the given
4499<var >Sigma</var> value.  The formula is:</p>
4500
4501<p class="text-center"><img class="img-thumbnail" alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"/> </p>
4502
4503<p>The <var >Sigma</var> value is the important argument, and
4504determines the actual amount of blurring that will take place. </p>
4505
4506<p>The <var >Radius</var> is only used to determine the size of the
4507array which will hold the calculated Gaussian distribution. It should be an
4508integer.  If not given, or set to zero, IM will calculate the largest possible
4509radius that will provide meaningful results for the Gaussian distribution.
4510</p>
4511
4512<p>The larger the <var >Radius</var> the radius the slower the
4513operation is. However too small a <var >Radius</var>, and severe
4514aliasing effects may result.  As a guideline, <var >Radius</var>
4515should be at least twice the <var >Sigma</var> value, though three
4516times will produce a more accurate result. </p>
4517
4518<p>This differs from the faster <a href="command-line-options.html#blur">-blur</a> operator in that a
4519full 2-dimensional convolution is used to generate the weighted average of the
4520neighboring pixels. </p>
4521
4522<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
4523pixels which are outside the image proper are blurred into the final result.
4524</p>
4525
4526
4527<div style="margin: auto;">
4528  <h3><a class="anchor" id="geometry"></a>-geometry <var>geometry</var></h3>
4529</div>
4530
4531<p class="magick-description">Set the preferred size and location of the image.</p>
4532
4533<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4534
4535<div style="margin: auto;">
4536  <h3><a class="anchor" id="gravity"></a>-gravity <var>type</var></h3>
4537</div>
4538
4539<p class="magick-description">Sets the current gravity suggestion for various other settings and options.</p>
4540
4541<p>Choices include: <code>NorthWest</code>, <code>North</code>,
4542<code>NorthEast</code>, <code>West</code>, <code>Center</code>, <code>East</code>,
4543<code>SouthWest</code>, <code>South</code>, <code>SouthEast</code>.  Use <a
4544href="command-line-options.html#list">-list gravity</a> to get a complete list of <a
4545href="command-line-options.html#gravity">-gravity</a> settings available in your ImageMagick
4546installation.</p>
4547
4548<p>The direction you choose specifies where to position text or subimages. For
4549example, a gravity of <code>Center</code> forces the text to be centered within
4550the image. By default, the image gravity is <code>undefined</code>. See <a
4551href="command-line-options.html#draw">-draw</a> for more details about graphic primitives.  Only the
4552text primitive of <a href="command-line-options.html#draw">-draw</a> is affected by the <a
4553href="command-line-options.html#gravity">-gravity</a> option.</p>
4554
4555<p>The <a href="command-line-options.html#gravity">-gravity</a> option is also used in concert with the
4556<a href="command-line-options.html#geometry">-geometry</a> setting and other settings or options that
4557take <var>geometry</var> as an argument, such as the <a
4558href="command-line-options.html#crop">-crop</a> option. </p>
4559
4560<p>If a <a href="command-line-options.html#gravity">-gravity</a> setting occurs before another option
4561or setting having a <var>geometry</var> argument that specifies an
4562offset, the offset is usually applied to the point within the image suggested
4563by the <a href="command-line-options.html#gravity">-gravity</a> argument.  Thus, in the following
4564command, for example, suppose the file <code>image.png</code> has dimensions
4565200x100. The offset specified by the argument to <a href="command-line-options.html#region">-region</a>
4566is (−40,+20). The argument to <a href="command-line-options.html#gravity">-gravity</a> is
4567<code>Center</code>, which suggests the midpoint of the image, at the point
4568(100,50). The offset (−40,20) is applied to that point, giving
4569(100−40,50+20)=(60,70), so the specified 10x10 region is located at
4570that point. (In addition, the <a href="command-line-options.html#gravity">-gravity</a> affects the
4571region itself, which is <var>centered</var> at the pixel
4572coordinate (60,70). (See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.)</p>
4573
4574<pre class="highlight"><code>convert image.png -gravity Center -region 10x10-40+20 \
4575  -negate output.png
4576</code></pre>
4577
4578<p>When used as an option to <a href="../www/composite.html">composite</a>, <a
4579href="command-line-options.html#gravity">-gravity</a> gives the direction that the image gravitates
4580within the composite.</p>
4581
4582<p>When used as an option to <a href="montage.html">montage</a>, <a
4583href="command-line-options.html#gravity">-gravity</a> gives the direction that an image gravitates
4584within a tile. The default gravity is <code>Center</code> for this purpose.</p>
4585
4586<p>Use <a href="command-line-options.html#gravity">+gravity</a> to return gravity to its default value.</p>
4587
4588
4589<div style="margin: auto;">
4590  <h3><a class="anchor" id="grayscale"></a>-grayscale <var>method</var></h3>
4591</div>
4592
4593<p class="magick-description">convert image to grayscale.</p>
4594
4595<p>This will use one of the <a href="command-line-options.html#intensity" >-intensity</a> methods to
4596convert the given image into a grayscale image. </p>
4597
4598<p>For example, to convert an image to (linear) Rec709Luminance grayscale,  type:</p>
4599
4600<pre class="highlight"><code>convert in.png -grayscale Rec709Luminance out.png
4601</code></pre>
4602
4603<p>which is equivalent to:</p>
4604
4605<pre class="highlight">
4606<code>convert in.png -colorspace RGB -colorspace Gray out.png</code>
4607or
4608<code>convert in.png -colorspace LinearGray out.png</code>
4609</pre>
4610
4611<p>Note that LinearGray is new as of Imagemagick 6.9.9-29 and 7.0.7-17.</p>
4612
4613<p>Similarly, to convert an image to (non-linear) Rec709Luma grayscale,  type:</p>
4614
4615<pre class="highlight"><code>convert in.png -grayscale Rec709Luma out.png
4616</code></pre>
4617
4618<p>which is equivalent to:</p>
4619
4620<pre class="highlight"><code>convert in.png -colorspace Gray out.png
4621</code></pre>
4622
4623<p>Note that a 'colorspace' intensity method will produce the same result
4624regardless of the current colorpsace of the image. But a 'mathematical'
4625intensity method depends on the current colorspace the image is currently
4626using. </p>
4627
4628<p>While this operation uses an <a href="command-line-options.html#intensity" >-intensity</a> method,
4629it does not use or set the <a href="command-line-options.html#intensity" >-intensity</a> setting, so
4630will not affect other operations that may use that setting.</p>
4631
4632
4633<div style="margin: auto;">
4634  <h3><a class="anchor" id="green-primary"></a>-green-primary <var>x,y</var></h3>
4635</div>
4636
4637<p class="magick-description">green chromaticity primary point.</p>
4638
4639
4640<div style="margin: auto;">
4641  <h3><a class="anchor" id="hald-clut"></a>-hald-clut</h3>
4642</div>
4643
4644<p class="magick-description">apply a Hald color lookup table to the image.</p>
4645
4646<p>A Hald color lookup table is a 3-dimensional color cube mapped to 2
4647dimensions.  Create it with the <code>HALD:</code> prefix (e.g. HALD:8).  You
4648can apply any color transformation to the Hald image and then use this option
4649to apply the transform to the image. </p>
4650
4651<pre class="highlight"><code>convert image.png hald.png -hald-clut transform.png
4652</code></pre>
4653
4654<p>This option provides a convenient method for you to use Gimp or Photoshop
4655to make color corrections to the Hald CLUT image and subsequently apply them
4656to multiple images using an ImageMagick script. </p>
4657
4658<p>Note that the representation is only of the normal RGB color space and that
4659the whole color value triplet is used for the interpolated lookup of the
4660represented Hald color cube image.  Because of this the operation is not <a
4661href="command-line-options.html#channel" >-channel</a> setting affected, nor can it adjust or modify an
4662images transparency or alpha/matte channel.</p>
4663
4664<p>See also <a href="command-line-options.html#clut" >-clut</a> which provides color value replacement
4665of the individual color channels, usually involving a simpler grayscale
4666image. E.g:  grayscale to color replacement, or modification by a histogram
4667mapping. </p>
4668
4669
4670<div style="margin: auto;">
4671  <h3><a class="anchor" id="help"></a>-help</h3>
4672</div>
4673
4674<p class="magick-description">print usage instructions.</p>
4675
4676<div style="margin: auto;">
4677  <h3><a class="anchor" id="highlight-color"></a>-highlight-color <var>color</var></h3>
4678</div>
4679
4680<p class="magick-description">when comparing images, emphasize pixel differences with this color.</p>
4681
4682<div style="margin: auto;">
4683  <h3><a class="anchor" id="hough-lines"></a>-hough-lines <var>width</var>x<var>height</var>{<var>+threshold</var>}</h3>
4684</div>
4685
4686<p class="magick-description">identify straight lines in the image (e.g. -hough-lines 9x9+195).</p>
4687
4688<p>Use the Hough line detector with any binary edge extracted image to locate and draw any straight lines that it finds.</p>
4689
4690<p>The process accumulates counts for every white pixel in the binary edge image for every possible orientation (for angles from 0 to 179 in 1 deg increments) and distance from the center of the image to the corners (in 1 px increments). It stores the counts in an accumulator matrix of angle vs distance. The size of the accumulator will be 180x(diagonal/2). Next it searches the accumulator for peaks in counts and converts the locations of the peaks to slope and intercept in the normal x,y input image space. The algorithm uses slope/intercepts to find the endpoints clipped to the bounds of the image. The lines are drawn from the given endpoints. The counts are a measure of the length of the lines.</p>.
4691
4692<p>The WxH arguments specify the filter size for locating the peaks in the Hough accumulator. The threshold excludes lines whose counts are less than the threshold value.</p>
4693
4694<p>Use <code><a href="command-line-options.html#background" >-background</a></code> to specify the color of the background onto which the lines will be drawn. The default is black.</p>
4695
4696<p>Use <code><a href="command-line-options.html#fill" >-fill</a></code> to specify the color of the lines. The default is black.</p>
4697
4698<p>Use <code><a href="command-line-options.html#stroke" >-stroke</a></code> and <code><a href="command-line-options.html#strokewidth" >-strokewidth</a></code> to specify the thickness of the lines. The default is black and no strokewidth.</p>
4699
4700<p>A text file listing the endpoints and counts may be created by using the suffix, .mvg, for the output image.</p>
4701
4702<p>Use <code><a href="command-line-options.html#define" >-define</a> hough-lines:accumulator=true</code> to return the accumulator image in addition to the lines image.</p>
4703
4704<div style="margin: auto;">
4705  <h3><a class="anchor" id="iconGeometry"></a>-iconGeometry <var>geometry</var></h3>
4706</div>
4707
4708<p class="magick-description">specify the icon geometry.</p>
4709
4710<p>Offsets, if present in the geometry specification, are handled in the same
4711manner as the <a href="command-line-options.html#geometry">-geometry</a> option, using X11 style to
4712handle negative offsets.</p>
4713
4714<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4715
4716<div style="margin: auto;">
4717  <h3><a class="anchor" id="iconic"></a>-iconic</h3>
4718</div>
4719
4720<p class="magick-description">start in icon mode in X Windows", 'animate', 'display</p>
4721
4722<div style="margin: auto;">
4723  <h3><a class="anchor" id="identify"></a>-identify</h3>
4724</div>
4725
4726<p class="magick-description">identify the format and characteristics of the image.</p>
4727
4728<p>This information is printed: image scene number; image name; image size;
4729the image class (<var>DirectClass</var> or <var>PseudoClass</var>); the total number of unique colors; and the
4730number of seconds to read and transform the image. Refer to <a href="miff.html">MIFF</a> for
4731a description of the image class.</p>
4732
4733<p>If <a href="command-line-options.html#colors">-colors</a> is also specified, the total unique colors
4734in the image and color reduction error values are printed. Refer to <a
4735href="../www/quantize.html">color
4736reduction algorithm</a> for a description of these values.</p>
4737
4738<p>If <a href="command-line-options.html#verbose">-verbose</a> precedes this option, copious
4739amounts of image properties are displayed including image statistics, profiles,
4740image histogram, and others.</p>
4741
4742<div style="margin: auto;">
4743  <h3><a class="anchor" id="ift"></a>-ift</h3>
4744</div>
4745
4746<p class="magick-description">implements the inverse discrete Fourier transform (DFT).</p>
4747
4748<p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
4749users in ImageMagick 6.6.0-9). It transforms a pair of magnitude and phase
4750images from the frequency domain to a single image in the normal or spatial
4751domain. See for example, <a
4752href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier Transform</a>,
4753<a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier Transform</a> and
4754<a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier Transform</a>.</p>
4755
4756<p>For example, depending upon the image format used to store the result of
4757the <a href="command-line-options.html#fft">-fft</a>, one would use either</p>
4758
4759<pre class="highlight"><code>convert fft_image.miff -ift fft_image_ift.png
4760</code></pre>
4761
4762<p>or</p>
4763
4764<pre class="highlight"><code>convert fft_image-0.png fft_image-1.png -ift fft_image_ift.png
4765</code></pre>
4766
4767<p>The resulting image may need to be cropped due to padding introduced when
4768the original image, prior to the <a href="command-line-options.html#fft">-fft</a> or <a
4769href="command-line-options.html#fft">+fft</a>, was not square or even dimensioned. Any padding is at
4770the right and/or bottom sides of the image.</p>
4771
4772<p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
4773use <a href="command-line-options.html#ift">-ift</a>.</p>
4774
4775<p>Use <a href="command-line-options.html#ift">+ift</a> (with HDRI enabled) to transform a pair of real
4776and imaginary images from the frequency domain to a single image in the normal
4777(spatial) domain.</p>
4778
4779<p>By default the IFT is not normalized (and the FFT is). Use "<code><a href="command-line-options.html#define" >-define</a> fourier:normalize=inverse</code> to explicitly normalize the IFT and unnormalize the FFT.</p>
4780
4781<div style="margin: auto;">
4782  <h3><a class="anchor" id="immutable"></a>-immutable</h3>
4783</div>
4784
4785<p class="magick-description">make image immutable.</p>
4786
4787<div style="margin: auto;">
4788  <h3><a class="anchor" id="implode"></a>-implode <var>factor</var></h3>
4789</div>
4790
4791<p class="magick-description">implode image pixels about the center.</p>
4792
4793<div style="margin: auto;">
4794  <h3><a class="anchor" id="insert"></a>-insert <var>index</var></h3>
4795</div>
4796
4797<p class="magick-description">insert the last image into the image sequence.</p>
4798
4799<p>This option takes last image in the current image sequence and inserts it
4800at the given index. If a negative index is used, the insert position is
4801calculated before the last image is removed from the sequence. As such
4802<code>-insert -1</code> will result in no change to the image sequence.</p>
4803
4804<p>The <code>+insert</code> option is equivalent to <code>-insert -1</code>. In
4805other words, insert the last image, at the end of the current image sequence.
4806Consequently this has no effect on the image sequence order.</p>
4807
4808<div style="margin: auto;">
4809  <h3><a class="anchor" id="intensity"></a>-intensity <var>method</var></h3>
4810</div>
4811
4812<p class="magick-description">method to generate intensity value from pixel.</p>
4813
4814<p>ImageMagick provides a number of methods used in situations where an
4815operator needs to determine a single grayscale value for some purpose, from
4816an image with red, green, and blue pixel components. Typically the
4817<code>Rec709Luma</code> formula is used, which is the same formula used when converting images to <code>-colorspace gray</code>. </p>
4818
4819<p>The following formulas are currently provided, and will first convert
4820the pixel values to linear-RGB or non-linear sRGB colorspace before
4821being applied to calculate the final greyscale value. </p>
4822
4823<dl class="row">
4824<dt class="col-md-4">Rec601Luma</dt><dd class="col-md-8">      0.298839R' + 0.586811G'+ 0.114350B'</dd>
4825<dt class="col-md-4">Rec601Luminance</dt><dd class="col-md-8"> 0.298839R + 0.586811G + 0.114350B</dd>
4826<dt class="col-md-4">Rec709Luma</dt><dd class="col-md-8">      0.212656R' + 0.715158G' + 0.072186B'</dd>
4827<dt class="col-md-4">Rec709Luminance</dt><dd class="col-md-8"> 0.212656R + 0.715158G + 0.072186B</dd>
4828<dt class="col-md-4">Brightness</dt><dd class="col-md-8">      max(R', G', B')</dd>
4829<dt class="col-md-4">Lightness</dt><dd class="col-md-8">       (min(R', G', B') + max(R', G', B')) / 2.0</dd>
4830</dl>
4831
4832<p>Note that the above R,G,B values is the image's linear-RGB values, while
4833R',G',B' are sRGB non-linear values. </p>
4834
4835<p>These intensity methods are mathematical in nature and will use the
4836current value in the images respective R,G,B channel regardless of
4837what that is, or what colorspace the image is currently using.</p>
4838
4839<dl class="row">
4840<dt class="col-md-4">Average</dt><dd class="col-md-8">(R' + G' + B') / 3.0</dd>
4841<dt class="col-md-4">MS</dt><dd class="col-md-8">(R'^2 + G'^2 + B'^2) / 3.0</dd>
4842<dt class="col-md-4">RMS</dt><dd class="col-md-8">sqrt( (R'^2 + G'^2 + B'^2) / 3.0 )</dd>
4843</dl>
4844
4845<p>These methods are often used for other purposes, such as generating a
4846grayscale difference image between two color images (using <a href="command-line-options.html#compose"
4847>-compose</a> '<code>Difference</code>' composition. </p>
4848
4849<p> For example The 'MS' (Mean Squared) setting is good for minimizing color
4850error comparisions.  While...  The method 'RMS' (Root Mean Squared) for
4851example is appropriate for calculating color vector distance, from a color
4852difference image.  This is equivalent to the color only component of the <a
4853href="command-line-options.html#fuzz" >-fuzz</a> factor color compare setting.  </p>
4854
4855<p>See also <a href="command-line-options.html#grayscale" >-grayscale</a> which applies one of the above
4856grayscaling formula directly to an image without setting the <a
4857href="command-line-options.html#intensity" >-intensity</a> setting.</p>
4858
4859<p>The <a href="command-line-options.html#colorspace" >-colorspace gray</a> image conversion also uses
4860the current intensity setting, but will always convert the image to the
4861appropriate sRGB or linear-RGB colorspace before appling the above
4862function.</p>
4863
4864<p>To print a complete list of possible pixel intensity setting methods, use <a href="command-line-options.html#list">-list intensity</a>.</p>
4865
4866<p>Operators affected by the <a href="command-line-options.html#intensity" >-intensity</a> setting include:</p>
4867
4868<pre class="highlight"><code>-adaptive-blur
4869-adaptive-sharpen
4870-black-threshold
4871-clut (when mapping greyscale CLUT image to alpha channel if set by -channels)
4872-colors for gray colorspace
4873-compose {LightenIntensity, DarkenIntensity, CopyOpacity, CopyBlack}
4874-contrast-stretch
4875-distort {ErodeIntensity, DilateIntensity}
4876-normalize
4877-random-threshold
4878-range-threshold
4879-selective-blur
4880-shade
4881-threshold
4882-tint
4883-white-threshold
4884</code></pre>
4885
4886<div style="margin: auto;">
4887  <h3><a class="anchor" id="intent"></a>-intent <var>type</var></h3>
4888</div>
4889
4890<p class="magick-description">use this type of rendering intent when managing the image color.</p>
4891
4892<p>Use this option to affect the color management operation of an image (see
4893<a href="command-line-options.html#profile">-profile</a>).  Choose from these intents: <code>Absolute,
4894Perceptual, Relative, Saturation</code>.</p>
4895
4896<p>The default intent is Perceptual for the sRGB colorspace and undefined for the RGB and gray colorspaces.</p>
4897
4898<p>To print a complete list of rendering intents, use <a href="command-line-options.html#list">-list intent</a>.</p>
4899
4900<div style="margin: auto;">
4901  <h3><a class="anchor" id="interlace"></a>-interlace <var>type</var></h3>
4902</div>
4903
4904<p class="magick-description">the type of interlacing scheme.</p>
4905
4906<p>Choose from:</p>
4907
4908<pre class="highlight"><code>none
4909line
4910plane
4911partition
4912JPEG
4913GIF
4914PNG
4915</code></pre>
4916
4917<p>This option is used to specify the type of interlacing scheme for raw image
4918formats such as <code>RGB</code> or <code>YUV</code>.</p>
4919
4920<p><code>None</code> means do not interlace (RGBRGBRGBRGBRGBRGB...),</p>
4921
4922<p><code>Line</code> uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.</p>
4923
4924<p><code>Plane</code> uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).</p>
4925
4926<p><code>Partition</code> is like plane except the different planes are saved to
4927individual files (e.g. image.R, image.G, and image.B).</p>
4928
4929<p>Use <code>Line</code> or <code>Plane</code> to create an <code>interlaced
4930PNG</code> or <code>GIF</code> or <code>progressive JPEG</code> image.</p>
4931
4932<p>To print a complete list of interlacing schemes, use <a href="command-line-options.html#list">-list
4933interlace</a>.</p>
4934
4935<div style="margin: auto;">
4936  <h3><a class="anchor" id="interpolate"></a>-interpolate <var>type</var></h3>
4937</div>
4938
4939<p class="magick-description">Set the pixel color interpolation method to use when looking up a color based on a floating point or real value.</p>
4940
4941<p>When looking up the color of a pixel using a non-integer floating point
4942value, you typically fall in between the pixel colors defined by the source
4943image. This setting determines how the color is determined from the colors of
4944the pixels surrounding that point.  That is how to determine the color of a
4945point that falls between two, or even four different colored pixels. </p>
4946
4947<dl class="row">
4948  <dt class="col-md-4">average</dt>
4949  <dd class="col-md-8">The average color of the surrounding four pixels</dd>
4950  <dt class="col-md-4">average4</dt>
4951  <dd class="col-md-8">The average color of the surrounding four pixels</dd>
4952  <dt class="col-md-4">average9</dt>
4953  <dd class="col-md-8">The average color of the surrounding nine pixels</dd>
4954  <dt class="col-md-4">average16</dt>
4955  <dd class="col-md-8">The average color of the surrounding sixteen pixels</dd>
4956  <dt class="col-md-4">background</dt>
4957  <dd class="col-md-8"> </dd>
4958  <dt class="col-md-4">bilinear</dt>
4959  <dd class="col-md-8">A double linear interpolation of pixels (the default)</dd>
4960  <dt class="col-md-4">blend</dt>
4961  <dd class="col-md-8"> </dd>
4962  <dt class="col-md-4">catrom</dt>
4963  <dd class="col-md-8">Fitted bicubic-spines of surrounding 16 pixels</dd>
4964  <dt class="col-md-4">integer</dt>
4965  <dd class="col-md-8">The color of the top-left pixel (floor function)</dd>
4966  <dt class="col-md-4">mesh</dt>
4967  <dd class="col-md-8">Divide area into two flat triangular interpolations</dd>
4968  <dt class="col-md-4">nearest-neighbor</dt>
4969  <dd class="col-md-8">The nearest pixel to the lookup point (rounded function)</dd>
4970  <dt class="col-md-4">spline</dt>
4971  <dd class="col-md-8">Direct spline curves (colors are blurred)</dd>
4972</dl>
4973
4974<p>This most important for distortion operators such as <a href="command-line-options.html#distort"
4975>-distort</a>, <a href="command-line-options.html#implode" >-implode</a>, <a href="command-line-options.html#transform"
4976>-transform</a> and <a href="command-line-options.html#fx" >-fx</a>. </p>
4977
4978<p>To print a complete list of interpolation methods, use <a href="command-line-options.html#list">-list interpolate</a>.</p>
4979
4980<p>See also <a href="command-line-options.html#virtual-pixel" >-virtual-pixel</a>, for control of the
4981lookup for positions outside the boundaries of the image. </p>
4982
4983
4984<div style="margin: auto;">
4985  <h3><a class="anchor" id="interline-spacing"></a>-interline-spacing <var>value</var></h3>
4986</div>
4987
4988<p class="magick-description">the space between two text lines.</p>
4989
4990<div style="margin: auto;">
4991  <h3><a class="anchor" id="interword-spacing"></a>-interword-spacing <var>value</var></h3>
4992</div>
4993
4994<p class="magick-description">the space between two words.</p>
4995
4996<div style="margin: auto;">
4997  <h3><a class="anchor" id="kerning"></a>-kerning <var>value</var></h3>
4998</div>
4999
5000<p class="magick-description">the space between two letters.</p>
5001
5002<div style="margin: auto;">
5003  <h3><a class="anchor" id="kuwahara"></a>-kuwahara <var>radius</var><br />-kuwahara <var>radius</var>x<var>sigma</var></h3>
5004</div>
5005
5006<p class="magick-description">edge preserving noise reduction filter.</p>
5007
5008<p>The <var >radius</var> is more important than the <var >sigma</var>. If <var >sigma</var> is left off, it will be computed automatically from the <var >radius</var> as <var >sigma</var>=<var >radius</var>-0.5. The <var >sigma</var> provides a bit of additional smoothing control.</p>
5009
5010
5011<div style="margin: auto;">
5012  <h3><a class="anchor" id="label"></a>-label <var>name</var></h3>
5013</div>
5014
5015<p class="magick-description">assign a label to an image.</p>
5016
5017<p>Use this option to assign a specific label to the image, as it is read in
5018or created.  You can use the <a href="command-line-options.html#set" >-set</a> operation to re-assign
5019a the labels of images already read in.  Image formats such as TIFF, PNG,
5020MIFF, supports saving the label information with the image.</p>
5021
5022<p>When saving an image to a <var>PostScript</var> file, any label
5023assigned to an image is used as a header string to print above the postscript
5024image. </p>
5025
5026<p>You can include the image filename, type, width, height, or other image
5027attribute by embedding special format character.  See <a href="../www/escape.html">Format and Print Image
5028Properties</a> for details of the percent escape codes.</p>
5029
5030<p>For example,</p>
5031
5032<pre class="highlight"><code>-label "%m:%f %wx%h"  bird.miff
5033</code></pre>
5034
5035<p>assigns an image label of <code>MIFF:bird.miff 512x480</code> to the
5036"<code>bird.miff</code>" image and whose width is 512 and height is 480, as it
5037is read in.  If a  <a href="command-line-options.html#label">+label</a> option was used instead, any
5038existing label present in the image would be used.  You can remove all labels
5039from an image by assigning the empty string. </p>
5040
5041<p>A label is not drawn on the image, but is embedded in the image datastream
5042via <var>Label</var> tag or similar mechanism. If you want the label to be
5043visible on the image itself, use the <a href="command-line-options.html#draw">-draw</a> option, or
5044during the final processing in the creation of an image montage.</p>
5045
5046<p>If the first character of <var>string</var> is <var>@</var>, the image label is read from a file titled by the
5047remaining characters in the string. Labels in a file are literal, no embedded
5048formatting characters are recognized.</p>
5049
5050
5051<div style="margin: auto;">
5052  <h3><a class="anchor" id="lat"></a>-lat <var>width</var><br />-lat <var>width</var>x<var>height</var>{<var>+-</var>}<var>offset</var>{<var>%</var>}</h3>
5053</div>
5054
5055<p class="magick-description">perform local adaptive threshold.</p>
5056
5057<p>Adaptively threshold each pixel based on the value of pixels in a
5058surrounding window.  If the current pixel is lighter than this average plus
5059the optional <code>offset</code>, then it is made white, otherwise it is made
5060black.  Small variations in pixel values such as found in scanned documents
5061can be ignored if offset is positive. A negative offset will make it more
5062sensitive to those small variations. </p>
5063
5064<p>This is commonly used to threshold images with an uneven background.  It is
5065based on the assumption that average color of the small window is the
5066the local background color, from which to separate the foreground color. </p>
5067
5068
5069<div style="margin: auto;">
5070  <h3><a class="anchor" id="layers"></a>-layers <var>method</var></h3>
5071</div>
5072
5073<p class="magick-description">handle multiple images forming a set of image layers or animation frames.</p>
5074
5075<p>Perform various image operation methods to a ordered sequence of images
5076which may represent either a set of overlaid 'image layers', a GIF disposal
5077animation, or a fully-'coalesced' animation sequence. </p>
5078
5079<table class="table table-sm table-striped">
5080  <tbody>
5081  <tr>
5082    <th style="width: 8%">Method</th>
5083    <th>Description</th>
5084  </tr>
5085
5086  <tr>
5087    <td>compare-any</td>
5088    <td>Crop the second and later frames to the smallest rectangle
5089        that contains all the differences between the two images.  No GIF <a
5090        href="command-line-options.html#dispose" >-dispose</a> methods are taken into account. </td>
5091  </tr>
5092
5093  <tr><td></td><td>This exactly the same as the <a href="command-line-options.html#deconstruct"
5094        >-deconstruct</a> operator, and does not preserve animations normal
5095        working, especially when animation used layer disposal methods such as
5096        '<code>Previous</code>' or '<code>Background</code>'. </td>
5097  </tr>
5098
5099  <tr>
5100    <td>compare-clear</td>
5101    <td>As '<code>compare-any</code>' but crop to the bounds of any
5102       opaque pixels which become transparent in the second frame. That is the
5103       smallest image needed to mask or erase pixels for the next frame. </td>
5104  </tr>
5105
5106  <tr>
5107    <td>compare-overlay</td>
5108    <td>As '<code>compare-any</code>' but crop to pixels that add
5109       extra color to the next image, as a result of overlaying color pixels.
5110       That is the smallest single overlaid image to add or change colors. </td>
5111   </tr>
5112
5113   <tr><td></td><td>This can be used with the <a href="command-line-options.html#compose" >-compose</a> alpha
5114       composition method '<code>change-mask</code>', to reduce the image to
5115       just the pixels that need to be overlaid. </td>
5116   </tr>
5117
5118  <tr>
5119    <td>coalesce</td>
5120    <td>Equivalent to a call to the <a href="command-line-options.html#coalesce"
5121        >-coalesce</a> operator.  Apply the layer disposal methods set in the
5122        current image sequence to form a fully defined animation sequence, as
5123        it should be displayed.  Effectively converting a GIF animation into a
5124        'film strip'-like animation.  </td>
5125  </tr>
5126
5127  <tr>
5128    <td>composite</td>
5129    <td>Alpha Composition of two image lists, separated by a
5130        "<code>null:</code>" image, with the destination image list first, and
5131        the source images last.  An image from each list are composited
5132        together until one list is finished. The separator image and source
5133        image lists are removed. </td>
5134  </tr>
5135
5136
5137  <tr><td></td>
5138    <td>The <a href="command-line-options.html#geometry" >-geometry</a> offset is adjusted according
5139        to <a href="command-line-options.html#gravity" >-gravity</a> in accordance of the virtual
5140        canvas size of the first image in each list. Unlike a normal <a
5141        href="command-line-options.html#composite" >-composite</a> operation, the canvas offset is also
5142        added to the final composite positioning of each image. </td> </tr>
5143
5144  <tr><td></td>
5145    <td>If one of the image lists only contains one image, that image is
5146        applied to all the images in the other image list, regardless of which
5147        list it is. In this case it is the image meta-data of the list which
5148        preserved.  </td>
5149  </tr>
5150
5151
5152  <tr>
5153    <td>dispose</td>
5154    <td>This like '<code>coalesce</code>' but shows the look of
5155        the animation after the layer disposal method has been applied, before
5156        the next sub-frame image is overlaid. That is the 'dispose' image that
5157        results from the application of the GIF <a href="command-line-options.html#dispose"
5158        >-dispose</a> method.  This allows you to check what
5159        is going wrong with a particular animation you may be developing.
5160        </td>
5161  </tr>
5162
5163  <tr>
5164    <td>flatten</td>
5165    <td>Create a canvas the size of the first images virtual
5166        canvas using the current <a href="command-line-options.html#background" >-background</a> color,
5167        and <a href="command-line-options.html#compose" >-compose</a> each image in turn onto that
5168        canvas.  Images falling outside that canvas is clipped. Final
5169        image will have a zero virtual canvas offset. </td>
5170  </tr>
5171
5172  <tr><td></td>
5173    <td>This usually used as one of the final 'image layering' operations
5174        overlaying all the prepared image layers into a final image. </td>
5175  </tr>
5176
5177  <tr><td></td>
5178    <td>For a single image this method can also be used to fillout a virtual
5179        canvas with real pixels, or to underlay an opaque color to remove
5180        transparency from an image.</td>
5181  </tr>
5182
5183
5184  <tr>
5185    <td>merge</td>
5186    <td>As 'flatten' method but merging all the given image
5187        layers to create a new layer image just large enough to hold all the
5188        image without clipping or extra space. The new images virtual offset
5189        will preserve the position of the new layer, even if this offset is
5190        negative.  The virtual canvas size of the first image is preserved.
5191        </td>
5192  </tr>
5193
5194  <tr><td></td><td>Caution is advised when handling image layers with
5195        negative offsets as few image file formats handle them correctly.
5196        Following this operation method with <a href="command-line-options.html#repage" >+repage</a>
5197        will remove the layer offset, and create an image in which all the
5198        overlaid image positions relative to each other is preserved, though
5199        not necessarily exactly where you specified them.
5200        </td>
5201  </tr>
5202
5203  <tr><td></td><td>See also 'trim-bounds' below which is closely related but
5204        without  doing the'flatten' to merge the images together. </td>
5205  </tr>
5206
5207  <tr>
5208    <td>mosaic</td>
5209    <td>As 'flatten' method but expanding the initial canvas size
5210        of the first image in a positive direction only so as to hold all the
5211        image layers.  However as a virtual canvas is 'locked' to the origin,
5212        by its own definition, image layers with a negative offsets will still
5213        become clipped by the top and left edges. See 'merge' or 'trim-bounds'
5214        if this could be a problem. </td>
5215
5216  </tr>
5217
5218  <tr><td></td><td>This method is commonly used to layout individual image
5219        using various offset but without knowing the final canvas size. The
5220        resulting image will, like 'flatten' not have any virtual offset, so
5221        can be saved to any image file format. </td>
5222  </tr>
5223
5224
5225  <tr>
5226    <td>optimize</td>
5227    <td>Optimize a coalesced animation, into GIF animation using
5228        a number of general techniques.  This currently a short cut to
5229        apply both the '<code>optimize-frame</code>', and
5230        '<code>optimize-transparency</code>' methods but may be expanded to
5231        include other optimization methods as they are developed. </td>
5232  </tr>
5233
5234  <tr>
5235    <td>optimize-frame</td>
5236    <td>Optimize a coalesced animation, into GIF animation by
5237        reducing the number of pixels per frame as much as possible by
5238        attempting to pick the best layer disposal method to use, while ensuring
5239        the result will continue to animate properly. </td>
5240  </tr>
5241
5242  <tr><td></td><td> There is no guarantee that the best optimization is found.
5243        But then no reasonably fast GIF optimization algorithm can do this.
5244        However this does seem to do better than most other GIF frame
5245        optimizers seen. </td>
5246  </tr>
5247
5248  <tr>
5249    <td>optimize-plus</td>
5250    <td>As '<code>optimize-frame</code>' but attempt to improve the
5251        overall optimization by adding extra frames to the animation, without
5252        changing the final look or timing of the animation.  The frames are
5253        added to attempt to separate the clearing of pixels from the
5254        overlaying of new additional pixels from one animation frame to the
5255        next.  If this does not improve the optimization (for the next frame
5256        only), it will fall back to the results of the previous normal
5257        '<code>optimize-frame</code>' technique. </td>
5258  </tr>
5259
5260  <tr><td></td><td>There is the possibility that the change in the disposal
5261        style will result in a worsening in the optimization of later frames,
5262        though this is unlikely. In other words there no guarantee that it is
5263        better than the normal '<code>optimize-frame</code>' technique. For some
5264        animations however you can get a vast improvement in the final
5265        animation size. </td>
5266  </tr>
5267
5268  <tr>
5269    <td>optimize-transparency</td>
5270    <td>Given a GIF animation, replace any pixel in the sub-frame
5271        overlay images with transparency, if it does not change the resulting
5272        animation by more than the current <a href="command-line-options.html#fuzz" >-fuzz</a> factor.
5273        </td>
5274  </tr>
5275
5276  <tr><td></td><td>This should allow a existing frame optimized GIF animation
5277        to compress into a smaller file size due to larger areas of one
5278        (transparent) color rather than a pattern of multiple colors repeating
5279        the current disposed image of the last frame. </td>
5280  </tr>
5281
5282  <tr>
5283    <td>remove-dups</td>
5284    <td>Remove (and merge time delays) of duplicate consecutive
5285        images, so as to simplify layer overlays of coalesced animations.
5286        </td>
5287  </tr>
5288
5289   <tr><td></td><td>Usually this a result of using a constant time delay
5290        across the whole animation, or after a larger animation was split into
5291        smaller sub-animations.  The duplicate frames could also have been
5292        used as part of some frame optimization methods. </td>
5293  </tr>
5294
5295  <tr>
5296    <td>remove-zero</td>
5297    <td>Remove any image with a zero time delay, unless ALL the
5298        images have a zero time delay (and is not a proper timed animation, a
5299        warning is then issued). </td>
5300  </tr>
5301
5302  <tr><td></td><td>In a GIF animation, such images are usually frames which
5303        provide partial intermediary updates between the frames that are
5304        actually displayed to users.  These frames are usually added for
5305        improved frame optimization in GIF animations. </td>
5306  </tr>
5307
5308  <tr>
5309    <td>trim-bounds</td>
5310    <td>Find the bounds of all the images in the current
5311        image sequence, then adjust the offsets so all images are contained on
5312        a minimal positive canvas. None of the image data is modified or
5313        merged, only the individual image virtual canvas size and offset.
5314        All the images is given the same canvas size, and and will have
5315        a positive offset, but will remain in the same position relative to
5316        each other. As a result of the minimal canvas size at least one image
5317        will touch every edge of that canvas.  The image data touching those
5318        edges however may be transparent.  </td>
5319  </tr>
5320
5321  <tr><td></td><td>The result is much like if you used 'merge' followed by a
5322        <a href="command-line-options.html#repage" >+repage</a> option, except that all the images
5323        have been kept separate.  If 'flatten' is used after using
5324        'trim-bounds' you will get the same result.  </td>
5325  </tr>
5326
5327  </tbody>
5328</table>
5329
5330<p>To print a complete list of layer types, use <a href="command-line-options.html#list">-list layers</a>.</p>
5331
5332<p>The operators <a href="command-line-options.html#coalesce" >-coalesce</a>, <a href="command-line-options.html#deconstruct"
5333>-deconstruct</a>, <a href="command-line-options.html#flatten" >-flatten</a>, and <a href="command-line-options.html#mosaic"
5334>-mosaic</a> are only aliases for the above methods and may be depreciated in
5335the future.  Also see  <a href="command-line-options.html#page" >-page</a>,  <a href="command-line-options.html#repage"
5336>-repage</a> operators, the <a href="command-line-options.html#compose" >-compose</a> setting, and the
5337GIF <a href="command-line-options.html#dispose" >-dispose</a> and  <a href="command-line-options.html#delay" >-delay</a>
5338settings. </p>
5339
5340
5341<div style="margin: auto;">
5342  <h3><a class="anchor" id="level"></a>-level <var>black_point</var>{,<var>white_point</var>}{<var>%</var>}{,<var>gamma</var>}</h3>
5343</div>
5344
5345<p class="magick-description">adjust the level of image channels.</p>
5346
5347<p>Given one, two or three values delimited with commas: black-point,
5348white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black and
5349white points range from 0 to <var>QuantumRange</var>, or from 0 to
5350100%; if the white point is omitted it is set to (<var>QuantumRange</var> - black_point), so as to center contrast changes.
5351If a <code>%</code> sign is present anywhere in the string, both black and white
5352points are percentages of the full color range.  Gamma will do a <a
5353href="command-line-options.html#gamma">-gamma</a> adjustment of the values.  If it is omitted, the
5354default of 1.0 (no gamma correction) is assumed.</p>
5355
5356<p>In normal usage (<code>-level</code>) the image values are stretched so that
5357the given '<code>black_point</code>' value in the original image is set to zero
5358(or black), while the given '<code>white_point</code>' value is set to <var>QuantumRange</var> (or white).  This provides you with direct
5359contrast adjustments to the image.  The '<code>gamma</code>' of the resulting
5360image will then be adjusted. </p>
5361
5362<p>From ImageMagick v6.4.1-9 using the plus form of the operator
5363(<code>+level</code>) or adding the special '!' flag anywhere in the argument
5364list, will cause the operator to do the reverse of the level adjustment.  That
5365is a zero, or <var>QuantumRange</var> value (black, and white, resp.)
5366in the original image, is adjusted to the given level values, allowing you to
5367de-contrast, or compress the channel values within the image. The
5368'<code>gamma</code>' is adjusted before the level adjustment to de-contrast the
5369image is made. </p>
5370
5371<p>Only the channels defined by the current <a href="command-line-options.html#channel">-channel</a>
5372setting are adjusted (defaults to RGB color channels only), allowing you to
5373limit the effect of this operator. </p>
5374
5375<p>Please note that the transparency channel is treated as 'matte'
5376values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
5377
5378
5379<div style="margin: auto;">
5380  <h3><a class="anchor" id="level-colors"></a>-level-colors {<var>black_color</var>}{,}{<var>white_color</var>}</h3>
5381</div>
5382
5383<p class="magick-description">adjust the level of an image using the provided dash separated colors.</p>
5384
5385<p>This function is exactly like <a href="command-line-options.html#level">-level</a>, except that the
5386value value for each color channel is determined by the
5387'<code>black_color</code>' and '<code>white_color</code>' colors given (as
5388described under the <a href="command-line-options.html#fill">-fill</a> option). </p>
5389
5390<p>This effectively means the colors provided to <code>-level-colors</code>
5391is mapped to become 'black' and 'white' respectively, with all the other
5392colors linearly adjusted (or clipped) to match that change. Each channel is
5393adjusted separately using the channel values of the colors specified. </p>
5394
5395<p>On the other hand the plus form of the operator (<code>+level-colors</code>)
5396will map the image color 'black' and 'white' to the given colors
5397respectively, resulting in a gradient (de-contrasting) tint of the image to
5398those colors. This can also be used to convert a plain grayscale image into a
5399one using the gradient of colors specified. </p>
5400
5401<p>By supplying a single color with a comma separator either before or after
5402that color, will just replace the respective 'black' or 'white' point
5403respectively.  But if no comma separator is provided, the given color is
5404used for both the black and white color points, making the operator either
5405threshold the images around that color (- form) or set all colors to that
5406color (+ form). </p>
5407
5408
5409<div style="margin: auto;">
5410  <h3><a class="anchor" id="limit"></a>-limit <var>type value</var></h3>
5411</div>
5412
5413<p class="magick-description">Set the pixel cache resource limit.</p>
5414
5415<p>Choose from: <code>width</code>, <code>height</code>, <code>area</code>, <code>memory</code>, <code>map</code>, <code>disk</code>, <code>file</code>, <code>thread</code>,  <code>throttle</code>, or <code>time</code>.</p>
5416
5417<p>The value for <code>file</code> is in number of files. The other limits are
5418in bytes. Define arguments for the memory, map, area, and disk resource limits
5419with SI prefixes (.e.g 100MB).</p>
5420
5421<p>By default the limits are 768 files, 3GB of image area, 1.5GiB memory, 3GiB
5422memory map, and 18.45EB of disk.  These limits are adjusted relative to the
5423available resources on your computer if this information is available.   When
5424any limit is reached, ImageMagick fails in some fashion but attempts to take
5425compensating actions, if possible. For example, the following limits
5426memory:</p>
5427
5428<pre class="highlight"><code>-limit memory 32MiB -limit map 64MiB
5429</code></pre>
5430
5431<p>Use <a href="command-line-options.html#list">-list resource</a> to list the current limits. For example, our system shows these limits:</p>
5432
5433<pre class="highlight"><code>-> identify -list resource
5434Resource limits:
5435  Width: 100MP
5436  Height: 100MP
5437  Area: 25.181GB
5438  Memory: 11.726GiB
5439  Map: 23.452GiB
5440  Disk: unlimited
5441  File: 768
5442  Thread: 12
5443  Throttle: 0
5444  Time: unlimited
5445</code></pre>
5446
5447<p>Requests for pixel storage to keep intermediate images are satisfied by one
5448of three resource categories: in-memory pool, memory-mapped files pool, and
5449disk pool (in that order) depending on the <a href="command-line-options.html#limit">&#x2011;limit</a> settings
5450and whether the system honors a resource request. If the total size of
5451allocated pixel storage in the given pool reaches the corresponding limit, the
5452request is passed to the next pool. Additionally, requests that exceed the
5453<code>area</code> limit automagically are allocated on disk.</p>
5454
5455<p>To illustrate how ImageMagick utilizes resource limits, consider a typical
5456image resource request.  First, ImageMagick tries to allocate the pixels in
5457memory.  The request might be denied if the resource request exceeds the
5458<code>memory</code> limit or if the system does not honor the request.  If
5459a memory request is not honored, the pixels are allocated to disk and the file
5460is memory-mapped. However, if the allocation request exceeds the
5461<code>map</code> limit, the resource allocation goes to disk. In all cases, if
5462the resource request exceeds the <code>area</code> limit, the pixels are
5463automagically cached to disk. If the disk has a hard limit, the program
5464fails.</p>
5465
5466<p>In most cases you simply do not need to concern yourself with resource
5467limits.  ImageMagick chooses reasonable defaults and most images do not tax
5468your computer resources.  Where limits do come in handy is when you process
5469images that are large or on shared systems where ImageMagick can consume all
5470or most of the available memory. In this case, the ImageMagick workflow slows
5471other processes or, in extreme cases, brings the system to a halt.  Under
5472these circumstances, setting limits give some assurances that the ImageMagick
5473workflow will not interfere with other concurrent uses of the computer.  For
5474example, assume you have a web interface that processes images uploaded from
5475the Internet.  To assure ImageMagick does not exceed 10MiB of memory you can
5476simply set the area limit to 10MiB:</p>
5477
5478<pre class="highlight"><code>-limit area 10MB
5479</code></pre>
5480
5481<p>Now whenever a large image is processed, the pixels are automagically
5482cached to disk instead of memory.  This of course implies that large images
5483typically process very slowly, simply because pixel processing in memory can
5484be an order of magnitude faster than on disk.  Because your web site users
5485might inadvertently upload a huge image to process, you should set a disk
5486limit as well:</p>
5487
5488<pre class="highlight"><code>-limit area 10MB -limit disk 500MB
5489</code></pre>
5490
5491<p>Here ImageMagick stops processing if an image requires more than 500MB of disk storage.</p>
5492
5493<p>In addition to command-line resource limit option, resources can be set
5494with <a href="resources.html#environment" >environment variables</a>. Set the
5495environment variables <code>MAGICK_AREA_LIMIT</code>,
5496<code>MAGICK_DISK_LIMIT</code>, <code>MAGICK_FILE_LIMIT</code>,
5497<code>MAGICK_MEMORY_LIMIT</code>, <code>MAGICK_MAP_LIMIT</code>,
5498<code>MAGICK_THREAD_LIMIT</code>, <code>MAGICK_TIME_LIMIT</code> for limits of
5499image area, disk space, open files, heap memory, memory map, number of threads
5500of execution, and maximum elapsed time in seconds respectively.</p>
5501
5502<p> Inquisitive users can try adding <a href="command-line-options.html#debug">-debug cache</a> to
5503their commands and then scouring the generated output for references to the
5504pixel cache, in order to determine how the pixel cache was allocated and how
5505resources were consumed. Advanced Unix/Linux users can pipe that output
5506through <code>grep memory|open|destroy|disk</code> for more readable sifting.
5507</p>
5508
5509<p>For more about ImageMagick's use of resources, see the section <b>Cache
5510Storage and Resource Requirements</b> on the <a href="architecture.html#cache
5511">Architecture</a> page.  </p>
5512
5513<div style="margin: auto;">
5514  <h3><a class="anchor" id="linear-stretch"></a>-linear-stretch <var>black-point</var><br />-linear-stretch <var>black-point</var>{x<var>white-point</var>}{<var>%</var>}</h3>
5515</div>
5516
5517<p class="magick-description">Linear with saturation stretch.</p>
5518
5519<p>This is very similar to <a href="command-line-options.html#contrast-stretch" >-contrast-stretch</a>,
5520and uses a 'histogram bin' to determine the range of color values that needs to
5521be stretched.  However it then stretches those colors using the <a
5522href="command-line-options.html#level" >-level</a> operator.</p>
5523
5524<p>As such while the initial determination may have 'binning' round off
5525effects, the image colors are stretched mathematically, rather than using the
5526histogram bins.  This makes the operator more accurate. </p>
5527
5528<p>note however that a <a href="command-line-options.html#linear-stretch" >-linear-stretch</a> of
5529'<code>0</code>' does nothing, while a value of '<code>1</code>' does a near
5530perfect stretch of the color range. </p>
5531
5532<p>See also <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect'
5533normalization of mathematical images. </p>
5534
5535<p>This operator is under review for re-development. </p>
5536
5537
5538<div style="margin: auto;">
5539  <h3><a class="anchor" id="linewidth"></a>-linewidth</h3>
5540</div>
5541
5542<p class="magick-description">the line width for subsequent draw operations.</p>
5543
5544<div style="margin: auto;">
5545  <h3><a class="anchor" id="liquid-rescale"></a>-liquid-rescale <var>geometry</var></h3>
5546</div>
5547
5548<p class="magick-description">rescale image with seam-carving.</p>
5549
5550<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5551
5552<div style="margin: auto;">
5553  <h3><a class="anchor" id="list"></a>-list <var>type</var></h3>
5554</div>
5555
5556<p class="magick-description">Print a list of supported arguments for various options or settings.  Choose from these list types:</p>
5557
5558<pre class="pre-scrollable"><code>
5559Align
5560Alpha
5561Boolean
5562Cache
5563Channel
5564Class
5565ClipPath
5566Coder
5567Color
5568Colorspace
5569Command
5570Complex
5571Compose
5572Compress
5573Configure
5574DataType
5575Debug
5576Decoration
5577Delegate
5578Direction
5579Dispose
5580Distort
5581Dither
5582Endian
5583Evaluate
5584FillRule
5585Filter
5586Font
5587Format
5588Function
5589Gravity
5590Intensity
5591Intent
5592Interlace
5593Interpolate
5594Kernel
5595Layers
5596LineCap
5597LineJoin
5598List
5599Locale
5600LogEvent
5601Log
5602Magic
5603Method
5604Metric
5605Mime
5606Mode
5607Morphology
5608Module
5609Noise
5610Orientation
5611PixelIntensity
5612Policy
5613PolicyDomain
5614PolicyRights
5615Preview
5616Primitive
5617QuantumFormat
5618Resource
5619SparseColor
5620Statistic
5621Storage
5622Stretch
5623Style
5624Threshold
5625Type
5626Units
5627Validate
5628VirtualPixel
5629</code></pre>
5630
5631<p>These lists vary depending on your version of ImageMagick. Use "<code>-list
5632list</code>" to get a complete listing of all the "<code>-list</code>" arguments
5633available:</p>
5634
5635<pre class="highlight"><code>identify -list list
5636</code></pre>
5637
5638<div style="margin: auto;">
5639  <h3><a class="anchor" id="log"></a>-log <var>string</var></h3>
5640</div>
5641
5642<p class="magick-description">Specify format for debug log.</p>
5643
5644<p>This option specifies the format for the log printed when the <a
5645href="command-line-options.html#debug">-debug</a> option is active.</p>
5646
5647<p>You can display the following components by embedding special format
5648characters:</p>
5649
5650<dl class="row">
5651<dt class="col-md-4">%d</dt><dd class="col-md-8">domain</dd>
5652<dt class="col-md-4">%e</dt><dd class="col-md-8">event</dd>
5653<dt class="col-md-4">%f</dt><dd class="col-md-8">function</dd>
5654<dt class="col-md-4">%l</dt><dd class="col-md-8">line</dd>
5655<dt class="col-md-4">%m</dt><dd class="col-md-8">module</dd>
5656<dt class="col-md-4">%p</dt><dd class="col-md-8">process ID</dd>
5657<dt class="col-md-4">%r</dt><dd class="col-md-8">real CPU time</dd>
5658<dt class="col-md-4">%t</dt><dd class="col-md-8">wall clock time</dd>
5659<dt class="col-md-4">%u</dt><dd class="col-md-8">user CPU time</dd>
5660<dt class="col-md-4">%%</dt><dd class="col-md-8">percent sign</dd>
5661<dt class="col-md-4">\n</dt><dd class="col-md-8">newline</dd>
5662<dt class="col-md-4">\r</dt><dd class="col-md-8">carriage return</dd>
5663</dl>
5664
5665<p>For example:</p>
5666
5667<pre class="highlight"><code>convert -debug coders -log "%u %m:%l %e" in.gif out.png
5668</code></pre>
5669
5670<p>The default behavior is to print all of the components.</p>
5671
5672<div style="margin: auto;">
5673  <h3><a class="anchor" id="loop"></a>-loop <var>iterations</var></h3>
5674</div>
5675
5676<p class="magick-description">add Netscape loop extension to your GIF animation.</p>
5677
5678<p>Set iterations to zero to repeat the animation an infinite number of times,
5679otherwise the animation repeats itself up to <var>iterations</var>
5680times.</p>
5681
5682<div style="margin: auto;">
5683  <h3><a class="anchor" id="lowlight-color"></a>-lowlight-color <var>color</var></h3>
5684</div>
5685
5686<p class="magick-description">when comparing images, de-emphasize pixel differences with this color.</p>
5687
5688<div style="margin: auto;">
5689  <h3><a class="anchor" id="magnify"></a>-magnify</h3>
5690</div>
5691
5692<p class="magick-description">double the size of the image with pixel art scaling.</p>
5693
5694
5695<div style="margin: auto;">
5696  <h3><a class="anchor" id="map"></a>-map <var>type</var></h3>
5697</div>
5698
5699<p class="magick-description">Display image using this <var>type</var>.</p>
5700
5701<p>Choose from these <var>Standard Colormap</var> types:</p>
5702
5703<pre class="highlight"><code>best
5704default
5705gray
5706red
5707green
5708blue
5709</code></pre>
5710
5711<p>The <var>X server</var> must support the <var>Standard
5712Colormap</var> you choose, otherwise an error occurs.  Use <code>list</code> as
5713the type and <code>display</code> searches the list of colormap types in
5714<code>top-to-bottom</code> order until one is located. See <var>xstdcmap(1)</var> for one way of creating Standard Colormaps.</p>
5715
5716
5717<div style="margin: auto;">
5718  <h3><a class="anchor" id="map_stream_"></a>-map <var>components</var></h3>
5719</div>
5720
5721<p class="magick-description">pixel map.</p>
5722
5723<p>Here are the valid components of a map:</p>
5724
5725<dl class="row">
5726<dt class="col-md-4">r</dt><dd class="col-md-8">  red pixel component</dd>
5727<dt class="col-md-4">g</dt><dd class="col-md-8">  green pixel component</dd>
5728<dt class="col-md-4">b</dt><dd class="col-md-8">  blue pixel component</dd>
5729<dt class="col-md-4">a</dt><dd class="col-md-8">  alpha pixel component (0 is transparent)</dd>
5730<dt class="col-md-4">o</dt><dd class="col-md-8">  opacity pixel component (0 is opaque)</dd>
5731<dt class="col-md-4">i</dt><dd class="col-md-8">  grayscale intensity pixel component</dd>
5732<dt class="col-md-4">c</dt><dd class="col-md-8">  cyan pixel component</dd>
5733<dt class="col-md-4">m</dt><dd class="col-md-8">  magenta pixel component</dd>
5734<dt class="col-md-4">y</dt><dd class="col-md-8">  yellow pixel component</dd>
5735<dt class="col-md-4">k</dt><dd class="col-md-8">  black pixel component</dd>
5736<dt class="col-md-4">p</dt><dd class="col-md-8">  pad component (always 0)</dd>
5737</dl>
5738
5739<p>You can specify as many of these components as needed in any order (e.g.
5740bgr).  The components can repeat as well (e.g. rgbr).</p>
5741
5742
5743<div style="margin: auto;">
5744  <h3><a class="anchor" id="mattecolor"></a>-mattecolor <var>color</var></h3>
5745</div>
5746
5747<p class="magick-description">Specify the color to be used with the <a href="command-line-options.html#frame">-frame</a> option.</p>
5748
5749<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
5750
5751<p>The default matte color is <code>#BDBDBD</code>, <span
5752style="background-color: #bdbdbd;">this shade of gray</span>.</p>
5753
5754<div style="margin: auto;">
5755  <h3><a class="anchor" id="maximum"></a>-maximum</h3>
5756</div>
5757
5758<p class="magick-description">return the maximum intensity of an image sequence.</p>
5759
5760<p>Select the 'maximum' value from all the surrounding pixels. </p>
5761
5762<p>This is legacy option from the <a href="command-line-options.html#statistic" >method</a> of the same
5763name. </p>
5764
5765<div style="margin: auto;">
5766  <h3><a class="anchor" id="median"></a>-median <var>geometry</var></h3>
5767</div>
5768
5769<p class="magick-description">apply a median filter to the image.</p>
5770
5771<p>Select the 'middle' value from all the surrounding pixels. </p>
5772
5773<p>This is legacy option from the <a href="command-line-options.html#statistic" >method</a> of the same
5774name. </p>
5775
5776<div style="margin: auto;">
5777  <h3><a class="anchor" id="mean-shift"></a>-mean-shift <var>width</var>x<var>height</var>{<var>+distance</var>{%}</h3>
5778</div>
5779
5780<p class="magick-description">image noise removal and color reduction/segmentation (e.g. -mean-shift 7x7+10%).</p>
5781
5782<p><var>width</var>x<var>height</var> is the window size and <var>distance</var> is the color distance measured in the range 0 to 1 or 0 to 100%</p>
5783
5784<p>The mean shift algorithm is iterative and thus slower the larger the window size. For each pixel, it gets all the pixels in the window centered at the pixel and excludes those that are outside the <var>radius=sqrt((width-1)(height-1)/4)</var> surrounding the pixel. From those pixels, it finds which of them are within the specified squared color distance from the current mean. It then computes a new x,y centroid from those coordinates and a new mean. This new x,y centroid is used as the center for a new window. This process is iterated until it converges and the final mean is then used to replace the original pixel value. It repeats this process for the next pixel, etc, until it processes all pixels in the image. Results are better when using other colorspaces rather than RGB. Recommend YIQ, YUV or YCbCr, which seem to give equivalent results.</p>
5785
5786<div style="margin: auto;">
5787  <h3><a class="anchor" id="metric"></a>-metric <var>type</var></h3>
5788</div>
5789
5790<p class="magick-description">Output to STDERR a measure of the differences between images according to the <var>type</var> given metric.</p>
5791
5792<p>Choose from:</p>
5793
5794<dl class="row">
5795<dt class="col-md-4">AE</dt><dd class="col-md-8">    absolute error count, number of different pixels (-fuzz affected)</dd>
5796<dt class="col-md-4">DSSIM</dt><dd class="col-md-8">  structural dissimilarity index</dd>
5797<dt class="col-md-4">FUZZ</dt><dd class="col-md-8">  mean color distance</dd>
5798<dt class="col-md-4">MAE</dt><dd class="col-md-8">   mean absolute error (normalized), average channel error distance</dd>
5799<dt class="col-md-4">MEPP</dt><dd class="col-md-8">  mean error per pixel (normalized mean error, normalized peak error)</dd>
5800<dt class="col-md-4">MSE</dt><dd class="col-md-8">   mean error squared, average of the channel error squared</dd>
5801<dt class="col-md-4">NCC</dt><dd class="col-md-8">   normalized cross correlation</dd>
5802<dt class="col-md-4">PAE</dt><dd class="col-md-8">   peak absolute (normalized peak absolute)</dd>
5803<dt class="col-md-4">PHASH</dt><dd class="col-md-8"> perceptual hash for the sRGB and HCLp colorspaces.  Specify an alternative colorspace with <code>-define phash:colorspaces=<var>colorspace,colorspace,...</var></code></dd>
5804<dt class="col-md-4">PSNR</dt><dd class="col-md-8">  peak signal to noise ratio</dd>
5805<dt class="col-md-4">RMSE</dt><dd class="col-md-8">  root mean squared (normalized root mean squared)</dd>
5806<dt class="col-md-4">SSIM</dt><dd class="col-md-8">  structural similarity index</dd>
5807</dl>
5808
5809<p>Control the '<code>AE</code>', or absolute count of pixels that are different,
5810with the <a href="command-line-options.html#fuzz" >-fuzz</a> factor (ignore pixels which
5811only changed by a small amount).  Use '<code>PAE</code>' to find the
5812size of the <a href="command-line-options.html#fuzz" >-fuzz</a> factor needed to make all pixels
5813'similar', while '<code>MAE</code>' determines the factor needed
5814for about half the pixels to be similar. </p>
5815
5816<p>The <code>MEPP</code> metric returns three different metrics
5817('<code>MAE</code>', '<code>MAE</code>' normalized, and '<code>PAE</code>'
5818normalized) from a single comparison run. </p>
5819
5820<p>The <code>SSIM</code> and <code>DSSIM</code> metrics respect these defines:
5821<code>-define compare:ssim-radius</code>, <code>-define compare:ssim-sigma</code>,
5822<code>-define compare:ssim-k1</code>, and <code>-define compare:ssim-k2</code>.</p>
5823
5824<p>To print a complete list of metrics, use the <a href="command-line-options.html#list">-list
5825metric</a> option.</p>
5826
5827
5828<div style="margin: auto;">
5829  <h3><a class="anchor" id="minimum"></a>-minimum</h3>
5830</div>
5831
5832<p class="magick-description">return the minimum intensity of an image sequence.</p>
5833
5834<p>Select the 'minimal' value from all the surrounding pixels. </p>
5835
5836<p>This is legacy option from the <a href="command-line-options.html#statistic" >method</a> of the same
5837name. </p>
5838
5839
5840
5841<div style="margin: auto;">
5842  <h3><a class="anchor" id="mode"></a>-mode <var>geometry</var></h3>
5843</div>
5844
5845<p class="magick-description">make each pixel the \'predominant color\' of the neighborhood.'</p>
5846
5847<div style="margin: auto;">
5848  <h3>-mode <var>value</var></h3>
5849</div>
5850
5851<p class="magick-description">Mode of operation.</p>
5852
5853<p>Choose the <var>value</var> from these styles: <code>Frame,
5854Unframe, or Concatenate</code></p>
5855
5856<p>Use the <a href="command-line-options.html#list" >-list</a> option with a '<code>Mode</code>' argument
5857for a list of <a href="command-line-options.html#mode" >-mode</a> arguments available in your
5858ImageMagick installation.</p>
5859
5860
5861<div style="margin: auto;">
5862  <h3><a class="anchor" id="modulate"></a>-modulate <var>brightness</var>[,<var>saturation</var>,<var>hue</var>]</h3>
5863</div>
5864
5865<p class="magick-description">Vary the <var>brightness</var>, <var>saturation</var>, and <var>hue</var> of an image.</p>
5866
5867<p>The arguments are given as a percentages of variation. A value of 100 means
5868no change, and any missing values are taken to mean 100.</p>
5869
5870<p>The <var>brightness</var> is a multiplier of the overall
5871brightness of the image, so 0 means pure black, 50 is half as bright, 200 is
5872twice as bright. To invert its meaning <a href="command-line-options.html#negate">-negate</a> the image
5873before and after. </p>
5874
5875<p>The <var>saturation</var> controls the amount of color in an
5876image. For example, 0 produce a grayscale image, while a large value such as
5877200 produce a very colorful, 'cartoonish' color.</p>
5878
5879<p>The <var>hue</var> argument causes a "rotation" of the colors
5880within the image by the amount specified. For example, 50 results in
5881a counter-clockwise rotation of 90, mapping red shades to purple, and so on.
5882A value of either 0 or 200 results in a complete 180 degree rotation of the
5883image. Using a value of 300 is a 360 degree rotation resulting in no change to
5884the original image. </p>
5885
5886<p>For example, to increase the color brightness by 20% and decrease the color
5887saturation by 10% and leave the hue unchanged, use <a
5888href="command-line-options.html#modulate">-modulate 120,90</a>.</p>
5889
5890<p>Use <a href="command-line-options.html#set">-set</a> attribute of '<code
5891>option:modulate:colorspace</code>' to specify which colorspace to
5892modulate.  Choose from <code>HCL</code>, <code>HCLp</code>, <code>HSB</code>, <code>HSI</code>, <code>HSL</code> (the default), <code>HSV</code>, <code>HWB</code>, or <code>LCH</code> (LCHuv).  For example,</p>
5893
5894<pre class="highlight"><code>convert image.png -set option:modulate:colorspace hsb -modulate 120,90 modulate.png
5895</code></pre>
5896
5897<div style="margin: auto;">
5898  <h3><a class="anchor" id="moments"></a>-moments</h3>
5899</div>
5900
5901<p class="magick-description">report image moments and perceptual hash.</p>
5902
5903
5904<div style="margin: auto;">
5905  <h3><a class="anchor" id="monitor"></a>-monitor</h3>
5906</div>
5907
5908<p class="magick-description">monitor progress.</p>
5909
5910
5911<div style="margin: auto;">
5912  <h3><a class="anchor" id="monochrome"></a>-monochrome</h3>
5913</div>
5914
5915<p class="magick-description">transform the image to black and white.</p>
5916
5917<div style="margin: auto;">
5918  <h3><a class="anchor" id="morph"></a>-morph <var>frames</var></h3>
5919</div>
5920
5921<p class="magick-description">morphs an image sequence.</p>
5922
5923<p>Both the image pixels and size are linearly interpolated to give the
5924appearance of a metamorphosis from one image to the next, over all the images
5925in the current image list. The added images are the equivalent of a <a
5926href="command-line-options.html#blend">-blend</a> composition. The <var>frames</var>
5927argument determine how many images to interpolate between each image. </p>
5928
5929
5930<div style="margin: auto;">
5931  <h3><a class="anchor" id="morphology"></a>-morphology</h3>
5932  <h3>-morphology <var>method</var>  <var>kernel</var></h3>
5933</div>
5934
5935<p class="magick-description">apply a morphology method to the image.</p>
5936
5937<p>Until I get around to writing an option summary for this, see <a
5938href="../Usage/morphology/" >IM Usage Examples,
5939Morphology</a>. </p>
5940
5941
5942<div style="margin: auto;">
5943  <h3><a class="anchor" id="mosaic"></a>-mosaic</h3>
5944</div>
5945
5946<p class="magick-description">an simple alias for the <a href="command-line-options.html#layers" >-layers</a> method "mosaic"</p>
5947
5948
5949<div style="margin: auto;">
5950  <h3><a class="anchor" id="motion-blur"></a>-motion-blur <var>radius</var><br />-motion-blur <var>radius</var>x<var>sigma</var>+<var>angle</var></h3>
5951</div>
5952
5953<p class="magick-description">simulate motion blur.</p>
5954
5955<p>Blur with the given radius, standard deviation (sigma), and angle.   The
5956angle given is the angle toward which the image is blurred.  That is the
5957direction people would consider the object is coming from. </p>
5958
5959<p>Note that the blur is not uniform distribution, giving the motion a
5960definite sense of direction of movement. </p>
5961
5962<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
5963pixels which are outside the image proper are blurred into the final result.
5964</p>
5965
5966<div style="margin: auto;">
5967  <h3><a class="anchor" id="name"></a>-name</h3>
5968</div>
5969
5970<p class="magick-description">name an image.</p>
5971<div style="margin: auto;">
5972  <h3><a class="anchor" id="negate"></a>-negate</h3>
5973</div>
5974
5975<p class="magick-description">replace each pixel with its complementary color.</p>
5976
5977<p>The red, green, and blue intensities of an image are negated. White becomes
5978black, yellow becomes blue, etc.  Use <a href="command-line-options.html#negate">+negate</a> to only
5979negate the grayscale pixels of the image.</p>
5980
5981<div style="margin: auto;">
5982  <h3><a class="anchor" id="noise"></a>-noise <var>geometry</var><br/>
5983  +noise <var>type</var></h3>
5984</div>
5985
5986<p class="magick-description">Add or reduce noise in an image.</p>
5987
5988<p>The principal function of noise peak elimination filter is to smooth the
5989objects within an image without losing edge information and without creating
5990undesired structures.  The central idea of the algorithm is to replace a pixel
5991with its next neighbor in value within a pixel window, if this pixel has been
5992found to be noise. A pixel is defined as noise if and only if this pixel is
5993a maximum or minimum within the pixel window.</p>
5994
5995<p>Use <code><a href="command-line-options.html#noise">-noise</a> <var>radius</var></code> to
5996specify the width of the neighborhood when reducing noise.  This is equivalent
5997to using a <code><a href="command-line-options.html#statistic" >-statistic</a> NonPeak</code> operation,
5998which should be used in preference.</p>
5999
6000<p>Use <a href="command-line-options.html#noise">+noise</a> followed by a noise <var>type</var> to add noise to an image. Choose from these noise
6001types:</p>
6002
6003<pre class="highlight"><code>Gaussian
6004Impulse
6005Laplacian
6006Multiplicative
6007Poisson
6008Random
6009Uniform
6010</code></pre>
6011
6012<p>The amount of noise added can be controlled by the <code><a
6013href="command-line-options.html#attenuate" >-attenuate</a></code> setting. If unset the value is
6014equivalent to 1.0, or a maximum noise addition.</p>
6015
6016<p>Note that Random will replace the image with noise rather than add noise to the image. Use Uniform, if you wish to add random noise to the image.</p>
6017
6018<p>To print a complete list of noises, use the <a href="command-line-options.html#list">-list noise</a> option.</p>
6019
6020<p>Also see the <a href="command-line-options.html#evaluate">-evaluate</a> noise functions that allows
6021the use of a controlling value to specify the amount of noise that should be
6022added to an image. </p>
6023
6024
6025<div style="margin: auto;">
6026  <h3><a class="anchor" id="normalize"></a>-normalize</h3>
6027</div>
6028
6029<p class="magick-description">Increase the contrast in an image by <var>stretching</var> the range of intensity values.</p>
6030
6031<p>The intensity values are stretched to cover the entire range of possible
6032values. While doing so, black-out at most <var>2%</var> of the pixels and
6033white-out at most <var>1%</var> of the pixels.</p>
6034
6035<p>Note that as of ImageMagick 6.4.7-0, <a href="command-line-options.html#normalize" >-normalize</a>
6036is equivalent to <a href="command-line-options.html#contrast-stretch" >-contrast-stretch 2%x1%</a>.
6037(Before this version, it was equivalent to <a href="command-line-options.html#contrast-stretch"
6038>-contrast-stretch 2%x99%</a>).</p>
6039
6040<p>All the channels are normalized in concert by the same amount so as to
6041preserve color integrity, when the default <a href="command-line-options.html#channel" >+channel</a>
6042setting is in use.  Specifying any other <a href="command-line-options.html#channel" >-channel</a>
6043setting will normalize the RGB channels independently.</p>
6044
6045<p>See  <a href="command-line-options.html#contrast-stretch" >-contrast-stretch</a> for more details.
6046Also see <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect' normalization
6047that is better suited to mathematically generated images. </p>
6048
6049<p>This operator is under review for re-development. </p>
6050
6051
6052<div style="margin: auto;">
6053  <h3><a class="anchor" id="opaque"></a>-opaque <var>color</var></h3>
6054</div>
6055
6056<p class="magick-description">change this color to the fill color within the image.</p>
6057
6058<p>The <var>color</var> argument is defined using the format
6059described under the <a href="command-line-options.html#fill" >-fill</a> option.  The <a href="command-line-options.html#fuzz"
6060>-fuzz</a> setting can be used to match and replace colors similar to the one
6061given.</p>
6062
6063<p>Use <a href="command-line-options.html#opaque">+opaque</a> to paint any pixel that does not match
6064the target color. </p>
6065
6066<p>The <a href="command-line-options.html#transparent">-transparent</a>  operator is exactly the same
6067as <a href="command-line-options.html#opaque" >-opaque</a> but replaces the matching color with
6068transparency rather than the current <a href="command-line-options.html#fill">-fill</a> color setting.
6069To ensure that it can do this it also ensures that the image has an alpha
6070channel enabled, as per "<code><a href="command-line-options.html#alpha" >-alpha</a> set</code>", for
6071the new transparent colors, and does not require you to modify the <a
6072href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
6073
6074
6075<div style="margin: auto;">
6076  <h3><a class="anchor" id="ordered-dither"></a>-ordered-dither <var>threshold_map</var>{,<var>level</var>...}</h3>
6077</div>
6078
6079<p class="magick-description">dither the image using a pre-defined  ordered dither <var>threshold map</var> specified, and a uniform color map with the
6080given number of <var>levels</var> per color channel.</p>
6081
6082<p>You can choose from these standard threshold maps:</p>
6083
6084<pre class="pre-scrollable"><code>
6085threshold   1x1   Threshold 1x1 (non-dither)
6086checks      2x1   Checkerboard 2x1 (dither)
6087o2x2        2x2   Ordered 2x2 (dispersed)
6088o3x3        3x3   Ordered 3x3 (dispersed)
6089o4x4        4x4   Ordered 4x4 (dispersed)
6090o8x8        8x8   Ordered 8x8 (dispersed)
6091h3x4a       4x1   Halftone 4x4 (angled)
6092h6x6a       6x1   Halftone 6x6 (angled)
6093h8x8a       8x1   Halftone 8x8 (angled)
6094h3x4o             Halftone 4x4 (orthogonal)
6095h6x6o             Halftone 6x6 (orthogonal)
6096h8x8o             Halftone 8x8 (orthogonal)
6097h36x16o           Halftone 16x16 (orthogonal)
6098c5x5b       c5x5  Circles 5x5 (black)
6099c5x5w             Circles 5x5 (white)
6100c6x6b       c6x6  Circles 6x6 (black)
6101c6x6w             Circles 6x6 (white)
6102c7x7b       c7x7  Circles 7x7 (black)
6103c7x7w             Circles 7x7 (white)
6104</code></pre>
6105
6106<p> The <code>threshold</code> generated a simple 50% threshold of the image.
6107This could be used with <var >level</var> to do the equivalent of <a
6108href="command-line-options.html#posterize" >-posterize</a> to reduce an image to basic primary colors.
6109</p>
6110
6111<p>The <code>checks</code> pattern produces a 3 level checkerboard  dither
6112pattern. That is a grayscale will become a pattern of solid black, solid
6113white, and  mid-tone colors into a checkerboard pattern of black and white.
6114</p>
6115
6116<p>You can define your own <var >threshold map</var> for ordered
6117dithering and halftoning your images, in either personal or system
6118<code>thresholds.xml</code> XML file. See <a href="resources.html" >Resources</a>
6119for more details of configuration files. </p>
6120
6121<p>To print a complete list of the thresholds that have been defined, use the
6122<a href="command-line-options.html#list" >-list threshold</a> option.</p>
6123
6124<p>Note that at this time the same threshold dithering map is used for all
6125color channels, no attempt is made to offset or rotate the map for different
6126channels is made, to create an offset printing effect. Also as the maps are
6127simple threshold levels, the halftone and circle maps will create incomplete
6128circles along the edges of a colored area. Also all the effects are purely
6129on/off boolean effects, without anti-aliasing to make the circles smooth
6130looking. Large dots can be made to look better with a small amount of blurring
6131after being created. </p>
6132
6133
6134<div style="margin: auto;">
6135  <h3><a class="anchor" id="orient"></a>-orient <var>image orientation</var></h3>
6136</div>
6137
6138<p class="magick-description">specify orientation of a digital camera image.</p>
6139
6140<p>Choose from these orientations:</p>
6141
6142<pre class="highlight"><code>bottom-left    right-top
6143bottom-right   top-left
6144left-bottom    top-right
6145left-top       undefined
6146right-bottom
6147</code></pre>
6148
6149<p>To print a complete list of orientations, use the <a href="command-line-options.html#list" >-list
6150orientation</a> option.</p>
6151
6152
6153<div style="margin: auto;">
6154  <h3><a class="anchor" id="page"></a>-page <var>geometry</var><br/>
6155  -page <var>media</var>[<var>offset</var>][{<var>^!&lt;&gt;</var>}]<br/>
6156  +page
6157  </h3>
6158</div>
6159
6160<p class="magick-description">Set the size and location of an image on the larger virtual canvas.</p>
6161
6162<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6163
6164<p>For convenience you can specify the page size using <var>media</var> (see below). Offsets can then be added as with other
6165<var>geometry</var> arguments (e.g. <a
6166href="command-line-options.html#page">-page</a> <code>Letter+43+43</code>).</p>
6167
6168<p>Use <var>media</var> as shorthand to specify the dimensions (<var>width</var>x<var>height</var>) of the <var>PostScript</var> page in dots per inch or a TEXT page in pixels.
6169The choices for a PostScript page are:</p>
6170
6171<dl class="row">
6172<dt class="col-md-4"> 11x17      </dt> <dd class="col-md-8">  792 x 1224</dd>
6173<dt class="col-md-4"> Ledger     </dt> <dd class="col-md-8"> 1224 x  792</dd>
6174<dt class="col-md-4"> Legal      </dt> <dd class="col-md-8">  612 x 1008</dd>
6175<dt class="col-md-4"> Letter     </dt> <dd class="col-md-8">  612 x  792</dd>
6176<dt class="col-md-4"> LetterSmall</dt> <dd class="col-md-8">  612 x  792</dd>
6177<dt class="col-md-4"> ArchE      </dt> <dd class="col-md-8"> 2592 x 3456</dd>
6178<dt class="col-md-4"> ArchD      </dt> <dd class="col-md-8"> 1728 x 2592</dd>
6179<dt class="col-md-4"> ArchC      </dt> <dd class="col-md-8"> 1296 x 1728</dd>
6180<dt class="col-md-4"> ArchB      </dt> <dd class="col-md-8">  864 x 1296</dd>
6181<dt class="col-md-4"> ArchA      </dt> <dd class="col-md-8">  648 x  864</dd>
6182<dt class="col-md-4"> A0         </dt> <dd class="col-md-8"> 2380 x 3368</dd>
6183<dt class="col-md-4"> A1         </dt> <dd class="col-md-8"> 1684 x 2380</dd>
6184<dt class="col-md-4"> A2         </dt> <dd class="col-md-8"> 1190 x 1684</dd>
6185<dt class="col-md-4"> A3         </dt> <dd class="col-md-8">  842 x 1190</dd>
6186<dt class="col-md-4"> A4         </dt> <dd class="col-md-8">  595 x  842</dd>
6187<dt class="col-md-4"> A4Small    </dt> <dd class="col-md-8">  595 x  842</dd>
6188<dt class="col-md-4"> A5         </dt> <dd class="col-md-8">  421 x  595</dd>
6189<dt class="col-md-4"> A6         </dt> <dd class="col-md-8">  297 x  421</dd>
6190<dt class="col-md-4"> A7         </dt> <dd class="col-md-8">  210 x  297</dd>
6191<dt class="col-md-4"> A8         </dt> <dd class="col-md-8">  148 x  210</dd>
6192<dt class="col-md-4"> A9         </dt> <dd class="col-md-8">  105 x  148</dd>
6193<dt class="col-md-4"> A10        </dt> <dd class="col-md-8">   74 x  105</dd>
6194<dt class="col-md-4"> B0         </dt> <dd class="col-md-8"> 2836 x 4008</dd>
6195<dt class="col-md-4"> B1         </dt> <dd class="col-md-8"> 2004 x 2836</dd>
6196<dt class="col-md-4"> B2         </dt> <dd class="col-md-8"> 1418 x 2004</dd>
6197<dt class="col-md-4"> B3         </dt> <dd class="col-md-8"> 1002 x 1418</dd>
6198<dt class="col-md-4"> B4         </dt> <dd class="col-md-8">  709 x 1002</dd>
6199<dt class="col-md-4"> B5         </dt> <dd class="col-md-8">  501 x  709</dd>
6200<dt class="col-md-4"> C0         </dt> <dd class="col-md-8"> 2600 x 3677</dd>
6201<dt class="col-md-4"> C1         </dt> <dd class="col-md-8"> 1837 x 2600</dd>
6202<dt class="col-md-4"> C2         </dt> <dd class="col-md-8"> 1298 x 1837</dd>
6203<dt class="col-md-4"> C3         </dt> <dd class="col-md-8">  918 x 1298</dd>
6204<dt class="col-md-4"> C4         </dt> <dd class="col-md-8">  649 x  918</dd>
6205<dt class="col-md-4"> C5         </dt> <dd class="col-md-8">  459 x  649</dd>
6206<dt class="col-md-4"> C6         </dt> <dd class="col-md-8">  323 x  459</dd>
6207<dt class="col-md-4"> Flsa       </dt> <dd class="col-md-8">  612 x  936</dd>
6208<dt class="col-md-4"> Flse       </dt> <dd class="col-md-8">  612 x  936</dd>
6209<dt class="col-md-4"> HalfLetter </dt> <dd class="col-md-8">  396 x  612</dd>
6210</dl>
6211
6212<p>This option is also used to place subimages when writing to a multi-image
6213format that supports offsets, such as GIF89 and MNG. When used for this
6214purpose the offsets are always measured from the top left corner of the canvas
6215and are not affected by the <a href="command-line-options.html#gravity">-gravity</a> option. To
6216position a GIF or MNG image, use <a href="command-line-options.html#page">-page</a><var>{+-}x{+-}y</var> (e.g.  -page +100+200). When writing to a MNG
6217file, a <a href="command-line-options.html#page">-page</a> option appearing ahead of the first image in
6218the sequence with nonzero width and height defines the width and height values
6219that are written in the <code>MHDR</code> chunk.  Otherwise, the MNG width and
6220height are computed from the bounding box that contains all images in the
6221sequence. When writing a GIF89 file, only the bounding box method is used to
6222determine its dimensions.</p>
6223
6224<p>For a PostScript page, the image is sized as in <a
6225href="command-line-options.html#geometry">-geometry</a> but positioned relative to the <var>lower
6226left-hand corner</var> of the page by {+-}<code>x</code><var>offset</var>{+-}<code>y</code> <var>offset</var>. Use <a
6227href="command-line-options.html#page">-page 612x792</a>, for example, to center the image within the
6228page. If the image size exceeds the PostScript page, it is reduced to fit the
6229page. The default gravity for the <a href="command-line-options.html#page">-page</a> option is <var>NorthWest</var>, i.e., positive <code>x</code> and <code>y</code> <var>offset</var> are measured rightward and downward from the top left
6230corner of the page, unless the <a href="command-line-options.html#gravity">-gravity</a> option is
6231present with a value other than <var>NorthWest</var>.</p>
6232
6233<p>The default page dimensions for a TEXT image is 612x792.</p>
6234
6235<p>This option is used in concert with <a href="command-line-options.html#density">-density</a>.</p>
6236
6237<p>Use <a href="command-line-options.html#page">+page</a> to remove the page settings for an image.</p>
6238
6239<div style="margin: auto;">
6240  <h3><a class="anchor" id="paint"></a>-paint <var>radius</var></h3>
6241</div>
6242
6243<p class="magick-description">simulate an oil painting.</p>
6244
6245<p>Each pixel is replaced by the most frequent color in a circular
6246neighborhood whose width is specified with <var>radius</var>.</p>
6247
6248<div style="margin: auto;">
6249  <h3><a class="anchor" id="path"></a>-path <var>path</var></h3></div>
6250
6251<p class="magick-description">write images to this path on disk.</p>
6252
6253<div style="margin: auto;">
6254  <h3><a class="anchor" id="pause_animate_"></a>-pause <var>seconds</var></h3>
6255</div>
6256
6257<p class="magick-description">Pause between animation loops</p>
6258
6259<p>Pause for the specified number of seconds before repeating the animation.</p>
6260
6261<div style="margin: auto;">
6262  <h3><a class="anchor" id="pause_import_"></a>-pause <var>seconds</var></h3>
6263</div>
6264
6265<p class="magick-description">Pause between snapshots.</p>
6266
6267<p>Pause for the specified number of seconds before taking the next snapshot.</p>
6268
6269<div style="margin: auto;">
6270  <h3><a class="anchor" id="perceptible"></a>-perceptible <var>epsilon</var></h3>
6271</div>
6272
6273<p class="magick-description">set each pixel whose value is less than |<var>epsilon</var>| to <var>-epsilon</var> or <var>epsilon</var> (whichever is closer) otherwise the pixel value remains unchanged.</p>
6274
6275<div style="margin: auto;">
6276  <h3><a class="anchor" id="ping"></a>-ping</h3>
6277</div>
6278
6279<p class="magick-description">efficiently determine image characteristics.</p>
6280
6281<div style="margin: auto;">
6282  <h3><a class="anchor" id="pointsize"></a>-pointsize <var>value</var></h3>
6283</div>
6284
6285<p class="magick-description">pointsize of the PostScript, OPTION1, or TrueType font.</p>
6286
6287<div style="margin: auto;">
6288  <h3><a class="anchor" id="polaroid"></a>-polaroid <var>angle</var></h3>
6289</div>
6290
6291<p class="magick-description">simulate a Polaroid picture.</p>
6292
6293<p>Use <code>+polaroid</code> to rotate the image at a random angle between -15 and +15 degrees.</p>
6294
6295<div style="margin: auto;">
6296  <h3><a class="anchor" id="poly"></a>-poly <var>"wt,exp ..."</var></h3>
6297</div>
6298
6299<p class="magick-description">combines multiple images according to a weighted sum of polynomials; one floating point weight (coefficient) and one floating point polynomial exponent (power) for each image expressed as comma separated pairs.</p>
6300
6301<p> The weights should typically be fractions between -1 and 1. But the sum of weights should be 1 or at least between 0 and 1 to avoid clamping in non-hdri mode at black and white.</p>
6302
6303<p>The exponents may be positive, negative or zero. A negative exponent is equivalent to 1 divided by the image raised to the corresponding positive exponent. A zero exponent always produces 1 scaled by quantumrange to white, i.e. wt*white, no matter what the image.</p>
6304
6305<p>The format is: <var>output = wt1*image1^exp1 + wt2*image2^exp2 </var>...</p>
6306
6307<p>Some simple uses are:</p>
6308<ul>
6309<li>A weighted sum of each image provided all weights add to unity and all exponents=1. If the the weights are all equal to 1/(number of images), then this is equivalent to <a href="command-line-options.html#profile">-evaluate-sequence</a> <var>mean</var>.</li>
6310<li>The sum of squares of two or more images, provided the weights are equal (and sum to 1 to avoid clamping) and the exponents equal 2.</li>
6311</ul>
6312
6313<p>Note that one may add a constant color to the expression simply by using xc:somecolor for one of the images and specifying the desired weight and exponent equal to 0.</p>
6314
6315<p>Similarly one may add white to the expression by simply using null: (or xc:white) for one of the images with the appropriate weight and exponent equal to 0.</p>
6316
6317
6318<div style="margin: auto;">
6319  <h3><a class="anchor" id="posterize"></a>-posterize <var>levels</var></h3>
6320</div>
6321
6322<p class="magick-description">reduce the image to a limited number of color levels per channel.</p>
6323
6324<p>Very low values of <var>levels</var>, e.g., 2, 3, 4, have the most
6325visible effect.</p>
6326
6327<div style="margin: auto;">
6328  <h3><a class="anchor" id="precision"></a>-precision <var>value</var></h3>
6329</div>
6330
6331<p class="magick-description">set the maximum number of significant digits to be printed.</p>
6332
6333<div style="margin: auto;">
6334  <h3><a class="anchor" id="preview"></a>-preview <var>type</var></h3>
6335</div>
6336
6337<p class="magick-description">image preview type.</p>
6338
6339<p>Use this option to affect the preview operation of an image (e.g.
6340<code>convert file.png -preview Gamma Preview:gamma.png</code>). Choose from
6341these previews:</p>
6342
6343<pre class="pre-scrollable"><code>
6344AddNoise
6345Blur
6346Brightness
6347Charcoal
6348Despeckle
6349Dull
6350EdgeDetect
6351Gamma
6352Grayscale
6353Hue
6354Implode
6355JPEG
6356OilPaint
6357Quantize
6358Raise
6359ReduceNoise
6360Roll
6361Rotate
6362Saturation
6363Segment
6364Shade
6365Sharpen
6366Shear
6367Solarize
6368Spiff
6369Spread
6370Swirl
6371Threshold
6372Wave
6373</code></pre>
6374
6375<p>To print a complete list of previews, use the <a href="command-line-options.html#list">-list preview</a> option.</p>
6376
6377<p>The default preview is <code>JPEG</code>.</p>
6378
6379<div style="margin: auto;">
6380  <h3><a class="anchor" id="print"></a>-print <var>string</var></h3>
6381</div>
6382
6383<p class="magick-description">interpret string and print to console.</p>
6384
6385<div style="margin: auto;">
6386  <h3><a class="anchor" id="process"></a>-process <var>command</var></h3>
6387</div>
6388
6389<p class="magick-description">process the image with a custom image filter.</p>
6390
6391<p>The command arguments has the form <code>"module arg1 arg2 arg3 ...
6392argN"</code> where <code>module</code> is the name of the module to invoke (e.g.
6393"Analyze") and arg1 arg2 arg3 ... argN are an arbitrary number of arguments to
6394pass to the process module.</p>
6395
6396<div style="margin: auto;">
6397  <h3><a class="anchor" id="profile"></a>-profile <var>filename</var><br/>
6398  +profile <var>profile_name</var></h3>
6399</div>
6400
6401<p class="magick-description">Manage ICM, IPTC, or generic profiles in an image.</p>
6402
6403<p>Using <a href="command-line-options.html#profile">-profile</a> <var>filename</var> adds an
6404ICM (ICC color management), IPTC (newswire information), or a generic profile
6405to the image.</p>
6406
6407<p>Use <a href="command-line-options.html#profile">+profile <var>profile_name</var></a> to
6408remove the indicated profile. ImageMagick uses standard filename globbing, so
6409wildcard expressions may be used to remove more than one profile.  Here we
6410remove all profiles from the image except for the XMP profile:  <code>+profile
6411"!xmp,*"</code>. </p>
6412
6413<p>Use <code>identify -verbose</code> to find out which profiles are in the
6414image file. Use <a href="command-line-options.html#strip">-strip</a> to remove all profiles (and
6415comments).</p>
6416
6417<p>To extract a profile, the <a href="command-line-options.html#profile">-profile</a> option is not
6418used. Instead, simply write the file to an image format such as <var>APP1, 8BIM, ICM,</var> or <var>IPTC</var>.</p>
6419
6420<p>For example, to extract the Exif data (which is stored in JPEG files in the
6421<var>APP1</var> profile), use.</p>
6422
6423<pre class="highlight"><code>convert cockatoo.jpg profile.exif
6424</code></pre>
6425
6426<p>It is important to note that results may depend on whether or not the
6427original image already has an included profile. Also, keep in mind that <a
6428href="command-line-options.html#profile">-profile</a> is an "operator" (as opposed to a "setting") and
6429therefore a conversion is made each time it is encountered, in order, in the
6430command-line. For instance, in the following example, if the original image is
6431CMYK with profile, a CMYK-CMYK-RGB conversion results.</p>
6432
6433<pre class="highlight"><code>convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff
6434</code></pre>
6435
6436<p>Furthermore, since ICC profiles are not necessarily symmetric, extra
6437conversion steps can yield unwanted results.  CMYK profiles are often very
6438asymmetric since they involve 3−&gt;4 and 4−&gt;3 channel mapping.
6439</p>
6440
6441<div style="margin: auto;">
6442  <h3><a class="anchor" id="quality"></a>-quality <var>value</var></h3>
6443</div>
6444
6445<p class="magick-description">JPEG/MIFF/PNG compression level.</p>
6446
6447<p>For the JPEG and MPEG image formats, quality is 1 (lowest image quality and
6448highest compression) to 100 (best quality but least effective compression).
6449The default is to use the estimated quality of your input image if it can
6450be determined, otherwise 92. When the quality is greater than 90, then the
6451chroma channels are not downsampled.
6452Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to specify the
6453factors for chroma downsampling.</p>
6454
6455<p>For the JPEG-2000 image format, quality is mapped using a non-linear
6456equation to the compression ratio required by the Jasper library. This
6457non-linear equation is intended to loosely approximate the quality provided by
6458the JPEG v1 format. The default quality value 100, a request for non-lossy
6459compression.  A quality of 75 results in a request for 16:1 compression.</p>
6460
6461<p>For the MNG and PNG image formats, the quality value sets the zlib
6462compression level (quality / 10) and filter-type (quality % 10).  The default
6463PNG "quality" is 75, which means compression level 7 with adaptive PNG
6464filtering, unless the image has a color map, in which case it means
6465compression level 7 with no PNG filtering.</p>
6466
6467<p>For compression level 0 (quality value less than 10), the Huffman-only
6468strategy is used, which is fastest but not necessarily the worst
6469compression.</p>
6470
6471<p>If filter-type is 4 or less, the specified PNG filter-type is used for
6472all scanlines:</p>
6473
6474<dl class="row">
6475<dt class="col-md-4">0</dt><dd class="col-md-8">none</dd>
6476<dt class="col-md-4">1</dt><dd class="col-md-8">sub</dd>
6477<dt class="col-md-4">2</dt><dd class="col-md-8">up</dd>
6478<dt class="col-md-4">3</dt><dd class="col-md-8">average</dd>
6479<dt class="col-md-4">4</dt><dd class="col-md-8">Paeth</dd>
6480</dl>
6481
6482<p>If filter-type is 5, adaptive filtering is used when quality is greater
6483than 50 and the image does not have a color map, otherwise no filtering is
6484used.</p>
6485
6486<p>If filter-type is 6, adaptive filtering
6487with <var>minimum-sum-of-absolute-values</var> is used.</p>
6488
6489<p>Only if the output is MNG, if filter-type is 7, the LOCO color
6490transformation (intrapixel differencing) and adaptive filtering
6491with <var>minimum-sum-of-absolute-values</var> are used.</p>
6492
6493<p>If the filter-type is 8 the zlib Z_RLE compression strategy (or the
6494Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
6495adaptive PNG filtering.</p>
6496
6497<p>If the filter-type is 9 the zlib Z_RLE compression strategy (or the
6498Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
6499no PNG filtering.</p>
6500
6501<p>The quality setting has no effect on the appearance or signature of PNG
6502and MNG images, since the compression is always lossless.</p>
6503
6504<p>Not all combinations of compression level, strategy, and PNG filter type
6505can be obtained using the -quality option.  For more precise control,
6506you can use the PNG:compression-level=N, PNG:compression-strategy=N, and
6507PNG:compression-filter=N defines, respectively, instead.
6508See <a href="command-line-options.html#define">-define</a>. Values from the defines take precedence
6509over values from the -quality option.</p>
6510
6511<p>For further information, see
6512the <a href="http://www.w3.org/pub/WWW/TR">PNG</a> specification.</p>
6513
6514<p>For the MIFF and TIFF image formats, quality/10 is the <a href="command-line-options.html#compress">Zip/BZip</a> compression level, which is 0 (worst but fastest compression) to 9 (best but slowest). It has no effect on the image appearance, since the compression is always lossless.</p>
6515
6516<p>For the BPG image format, quality/2 is the actual BPG compression level (range from 0 to 51).</p>
6517
6518<div style="margin: auto;">
6519  <h3><a class="anchor" id="quantize"></a>-quantize <var>colorspace</var></h3>
6520</div>
6521
6522<p class="magick-description">reduce colors using this colorspace.</p>
6523
6524<p>This setting defines the colorspace used to sort out and reduce the number
6525of colors needed by an image (for later dithering) by operators such as <a
6526href="command-line-options.html#colors" >-colors</a>, Note that color reduction also happens
6527automatically when saving images to color-limited image file formats, such as
6528GIF, and PNG8.</p>
6529
6530
6531<div style="margin: auto;">
6532  <h3><a class="anchor" id="quiet"></a>-quiet</h3>
6533</div>
6534
6535<p class="magick-description">suppress all warning messages. Error messages are still reported.</p>
6536
6537<div style="margin: auto;">
6538  <h3><a class="anchor" id="radial-blur"></a>-radial-blur  <var>angle</var></h3>
6539</div>
6540
6541<p class="magick-description">Blur around the center of the image.</p>
6542
6543<p>Note that this is actually a rotational blur rather than a radial and as
6544such actually mis-named. </p>
6545
6546<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
6547pixels which are outside the image proper are blurred into the final result.
6548</p>
6549
6550
6551<div style="margin: auto;">
6552  <h3><a class="anchor" id="raise"></a>-raise <var>thickness</var></h3>
6553</div>
6554
6555<p class="magick-description">Lighten or darken image edges.</p>
6556
6557<p>This will create a 3-D effect. Use <a href="command-line-options.html#raise">-raise</a> to create
6558a raised effect, otherwise use <a href="command-line-options.html#raise">+raise</a>.  </p>
6559
6560<p>Unlike the similar <a href="command-line-options.html#frame">-frame</a> option, <a
6561href="command-line-options.html#raise">-raise</a> does not alter the dimensions of the image.</p>
6562
6563<div style="margin: auto;">
6564  <h3><a class="anchor" id="random-threshold"></a>-random-threshold <var>low</var>x<var>high</var></h3>
6565</div>
6566
6567<p class="magick-description">Apply a random threshold to the image.</p>
6568
6569<div style="margin: auto;">
6570  <h3><a class="anchor" id="range-threshold"></a>-range-threshold <var>low-black</var>,<var>low-white</var>,<var>high-white</var>,<var>high-black</var></h3>
6571</div>
6572
6573<p class="magick-description">Perform either hard or soft thresholding within some range of values in an image.</p>
6574
6575<div style="margin: auto;">
6576  <h3><a class="anchor" id="read-mask"></a>-read-mask
6577<var>filename</var></h3>
6578</div>
6579
6580<p class="magick-description">Prevent updates to image pixels specified by the mask.</p>
6581
6582<p>This the same as using a mask used for composite masking operations, with
6583grayscale values causing blended updates of the image the mask is attached to.
6584</p>
6585
6586<p>Use <a href="command-line-options.html#read-mask">+read-mask</a> to remove the mask from images.</p>
6587
6588<p>Also see <a href="command-line-options.html#clip-mask">-clip-mask</a> which work in the same way,
6589but with strict boolean masking. </p>
6590
6591<div style="margin: auto;">
6592  <h3><a class="anchor" id="red-primary"></a>-red-primary <var>x,y</var></h3>
6593</div>
6594
6595<p class="magick-description">Set the red chromaticity primary point.</p>
6596
6597<div style="margin: auto;">
6598  <h3><a class="anchor" id="regard-warnings"></a>-regard-warnings</h3>
6599</div>
6600
6601<p class="magick-description">Pay attention to warning messages.</p>
6602
6603<p>This option causes some warnings in some image formats to be treated
6604as errors. </p>
6605
6606<div style="margin: auto;">
6607  <h3><a class="anchor" id="remap"></a>-remap <var>filename</var></h3>
6608</div>
6609
6610<p class="magick-description">Reduce the number of colors in an image to the colors used by this image.</p>
6611
6612<p>If the <a href="command-line-options.html#dither">-dither</a> setting is enabled (the default) then
6613the given colors are dithered over the image as necessary, otherwise the closest
6614color (in RGB colorspace) is selected to replace that pixel in the image. </p>
6615
6616<p>As a side effect of applying a <a href="command-line-options.html#remap">-remap</a> of colors across all
6617images in the current image sequence, all the images will have the same color
6618table.  That means that when saved to a file format such as GIF, it will use
6619that color table as a single common or global color table, for all the images,
6620without requiring extra local color tables. </p>
6621
6622<p>Use <a href="command-line-options.html#remap">+remap</a> to reduce all images in the current image
6623sequence to use a common color map over all the images. This equivalent to
6624appending all the images together (without extra background colors) and color
6625reducing those images using <a href="command-line-options.html#colors">-colors</a> with a 256 color
6626limit, then <a href="command-line-options.html#remap">-remap</a> those colors over the original list of
6627images. This ensures all the images follow a single color map. </p>
6628
6629<p>If the number of colors over all the images is less than 256, then <a
6630href="command-line-options.html#remap">+remap</a> should not perform any color reduction or dithering, as
6631no color changes are needed. In that case, its only effect is to force the use
6632of a global color table.  This recommended after using either <a
6633href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#ordered-dither">-ordered-dither</a> to
6634reduce the number of colors in an animated image sequence. </p>
6635
6636<p>Note, the remap image colormap has at most 8-bits of precision. Deeper color maps are automagically coalesced with other colors to meet this requirement.</p>
6637
6638<div style="margin: auto;">
6639  <h3><a class="anchor" id="region"></a>-region <var>geometry</var></h3>
6640</div>
6641
6642<p class="magick-description">Set a region in which subsequent operations apply.</p>
6643
6644<p>The <var>x</var> and <var>y</var> offsets are treated
6645in the same manner as in <a href="command-line-options.html#crop">-crop</a>.</p>
6646
6647<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6648
6649<p>Use <code>+region</code> to remove any previously set regions.</p>
6650
6651<div style="margin: auto;">
6652  <h3><a class="anchor" id="remote"></a>-remote</h3>
6653</div>
6654
6655<p class="magick-description">perform a remote operation.</p>
6656
6657<p>The only command recognized is the name of an image file to load.</p>
6658
6659<p>If you have more than one <a href="display.html">display</a> application
6660running simultaneously, use the <a href="command-line-options.html#window"> window</a> option to
6661specify which application to control.</p>
6662
6663<div style="margin: auto;">
6664  <h3><a class="anchor" id="render"></a>-render</h3>
6665</div>
6666
6667<p class="magick-description">render vector operations.</p>
6668
6669<p>Use <a href="command-line-options.html#render">+render</a> to turn off rendering vector operations.
6670This useful when saving the result to vector formats such as MVG or SVG.</p>
6671
6672<div style="margin: auto;">
6673<h3><a class="anchor" id="repage"></a>-repage <var>geometry</var></h3>
6674</div>
6675
6676<p class="magick-description">Adjust the canvas and offset information of the image.</p>
6677
6678<p>This option is like <a href="command-line-options.html#page">-page</a> but acts as an image operator
6679rather than a setting.  You can separately set the canvas size or the offset
6680of the image on that canvas by only providing those components. </p>
6681
6682<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6683
6684<p>If a <code>!</code> flag is given the offset given is added to the existing
6685offset to move the image relative to its previous position. This useful for
6686animation sequences. </p>
6687
6688<p>A given a canvas size of zero such as '<code>0x0</code>' forces it to
6689recalculate the canvas size so the image (at its current offset) will appear
6690completely on that canvas (unless it has a negative offset).</p>
6691
6692<p>Use <a href="command-line-options.html#repage">+repage</a> to completely remove/reset the virtual
6693canvas meta-data from the images. </p>
6694
6695<p>The <a href="command-line-options.html#set">-set</a> '<code>page</code>' option can be used to
6696directly assign virtual canvas meta-data. </p>
6697
6698
6699<div style="margin: auto;">
6700  <h3><a class="anchor" id="resample"></a>-resample <var>horizontal</var>x<var>vertical</var></h3>
6701</div>
6702
6703<p class="magick-description">Resample image to specified horizontal and vertical resolution.</p>
6704
6705<p>Resize the image so that its rendered size remains the same as the original
6706at the specified target resolution. For example, if a 300 DPI image renders at
67073 inches by 2 inches on a 300 DPI device, when the image has been resampled to
670872 DPI, it will render at 3 inches by 2 inches on a 72 DPI device.  Note that
6709only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of
6710storing the image resolution. For formats which do not support an image
6711resolution, the original resolution of the image must be specified via <a
6712href="command-line-options.html#density">-density</a> on the command line prior to specifying the
6713resample resolution.</p>
6714
6715<p>Note that Photoshop stores and obtains image resolution from a proprietary
6716embedded profile. If this profile exists in the image, then Photoshop will
6717continue to treat the image using its former resolution, ignoring the image
6718resolution specified in the standard file header.</p>
6719
6720<div style="margin: auto;">
6721  <h3><a class="anchor" id="resize"></a>-resize <var>geometry</var></h3>
6722</div>
6723
6724<p class="magick-description">Resize an image.</p>
6725
6726<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets, if present in the geometry string, are
6727ignored, and the <a href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
6728
6729<p>If the <a href="command-line-options.html#filter">-filter</a> option
6730or <code>-define filter:option=value</code> precedes the <a
6731href="command-line-options.html#resize">-resize</a> option, the image is resized with the specified
6732filter.</p>
6733
6734<p>Many image processing algorithms assume your image is in a linear-light
6735coding.  If your image is gamma-corrected, you can remove the nonlinear gamma
6736correction, apply the transform, then restore it like this:</p>
6737
6738<pre class="highlight"><code>convert portrait.jpg -gamma .45455 -resize 25% -gamma 2.2  \
6739  -quality 92 passport.jpg
6740</code></pre>
6741
6742<div style="margin: auto;">
6743  <h3><a class="anchor" id="respect-parentheses"></a>-respect-parentheses</h3>
6744</div>
6745
6746<p class="magick-description">settings remain in effect until parenthesis boundary.</p>
6747
6748<div style="margin: auto;">
6749  <h3><a class="anchor" id="reverse"></a>-reverse</h3>
6750</div>
6751
6752<p class="magick-description">Reverse the order of images in the current image list.</p>
6753
6754
6755<div style="margin: auto;">
6756  <h3><a class="anchor" id="roll"></a>-roll {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h3>
6757</div>
6758
6759<p class="magick-description">roll an image vertically or horizontally by the amount given.</p>
6760
6761<p>A negative <var>x</var> offset rolls the image right-to-left.
6762A negative <var>y</var> offset rolls the image bottom-to-top.</p>
6763
6764
6765<div style="margin: auto;">
6766  <h3><a class="anchor" id="rotate"></a>-rotate <var>degrees</var>{<var>&lt;</var>}{<var>&gt;</var>}</h3>
6767</div>
6768
6769<p class="magick-description">Apply Paeth image rotation (using shear operations) to the image.</p>
6770
6771<p>Use <code>&gt;</code> to rotate the image only if its width exceeds the
6772height. <code>&lt;</code> rotates the image <var>only</var> if its width is less
6773than the height. For example, if you specify <code>-rotate "-90&gt;"</code> and
6774the image size is 480x640, the image is not rotated. However, if the image is
6775640x480, it is rotated by -90 degrees. If you use <code>&gt;</code> or
6776<code>&lt;</code>, enclose it in quotation marks to prevent it from being
6777misinterpreted as a file redirection.</p>
6778
6779<p>Empty triangles in the corners, left over from rotating the image, are
6780filled with the <code>background</code> color. </p>
6781
6782<p>See also the <a href="command-line-options.html#distort">-distort</a> operator and specifically the
6783'<code>ScaleRotateTranslate</code>' distort method. </p>
6784
6785
6786<div style="margin: auto;">
6787  <h3><a class="anchor" id="sample"></a>-sample <var>geometry</var></h3>
6788</div>
6789
6790<p class="magick-description">minify / magnify the image with pixel subsampling and pixel replication, respectively.</p>
6791
6792<p>Change the image size simply by directly sampling the pixels original
6793from the image.  When magnifying, pixels are replicated in blocks.  When
6794minifying, pixels are sub-sampled (i.e., some rows and columns are skipped
6795over). </p>
6796
6797<p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6798a <a href="command-line-options.html#filter">-filter</a> setting of <code>point</code> (nearest
6799neighbor), though <a href="command-line-options.html#sample">-sample</a> is a lot faster, as it
6800avoids all the filter processing of the image. As such it completely ignores
6801the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6802
6803<p>The key feature of the <a href="command-line-options.html#sample">-sample</a> is that no new colors
6804will be added to the resulting image, though some colors may disappear. </p>
6805
6806<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets, if present in the geometry string, are
6807ignored, unlike <a href="command-line-options.html#resize">-resize</a>. </p>
6808
6809
6810<p>The actual sampling point is the middle of the sub-region being sampled.
6811As such a single pixel sampling of an image will take the middle pixel, (or
6812top-left-middle if image has even dimensions).  However the <a
6813href="command-line-options.html#define">-define</a> '<code>sample:offset</code>' can be set to modify
6814this position some other location within each sub-region being sampled, as
6815a percentage offset.</p>
6816
6817<p>By default this value is '<code>50</code>' for the midpoint, but could be set
6818to '<code>0</code>' for top-left, '<code>100</code>' for bottom-right, or with
6819separate X and Y offsets such as '<code>0x50</code>' for left-middle edge of
6820sampling sub-region.</p>
6821
6822
6823<div style="margin: auto;">
6824  <h3><a class="anchor" id="sampling-factor"></a>-sampling-factor <var>horizontal-factor</var>x<var>vertical-factor</var></h3>
6825</div>
6826
6827<p class="magick-description">sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.</p>
6828
6829<p>This option specifies the sampling factors to be used by the JPEG encoder
6830for chroma downsampling. If this option is omitted, the JPEG library will use
6831its own default values. When reading or writing the YUV format and when
6832writing the M2V (MPEG-2) format, use <a
6833href="command-line-options.html#sampling-factor">-sampling-factor 2x1</a> or <a
6834href="command-line-options.html#sampling-factor">-sampling-factor 4:2:2</a> to specify the 4:2:2
6835downsampling method.</p>
6836
6837<div style="margin: auto;">
6838  <h3><a class="anchor" id="scale"></a>-scale <var>geometry</var></h3>
6839</div>
6840
6841<p class="magick-description">minify / magnify the image with pixel block averaging and pixel replication, respectively.</p>
6842
6843<p>Change the image size simply by replacing pixels by averaging pixels
6844together when minifying, or replacing pixels when magnifying.  </p>
6845
6846<p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6847a <a href="command-line-options.html#filter">-filter</a> setting of <code>box</code>.  Though it is a lot
6848faster, as it avoids all the filter processing of the image. As such it
6849completely ignores the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6850
6851<p>If when shrinking (minifying) images the original image is some integer
6852multiple of the new image size, the number of pixels averaged together to
6853produce the new pixel color is the same across the whole image. This is
6854a special case known as 'binning' and is often used as a method of reducing
6855noise in image such as those generated by digital cameras, especially in low
6856light conditions. </p>
6857
6858
6859<div style="margin: auto;">
6860  <h3><a class="anchor" id="scene"></a>-scene <var>value</var></h3>
6861</div>
6862
6863<p class="magick-description">set scene number.</p>
6864
6865<p>This option sets the scene number of an image or the first image in an image sequence.</p>
6866
6867<div style="margin: auto;">
6868  <h3><a class="anchor" id="screen"></a>-screen</h3>
6869</div>
6870
6871<p class="magick-description">specify the screen to capture.</p>
6872
6873<p>This option indicates that the GetImage request used to obtain the image
6874should be done on the root window, rather than directly on the specified
6875window. In this way, you can obtain pieces of other windows that overlap the
6876specified window, and more importantly, you can capture menus or other popups
6877that are independent windows but appear over the specified window.</p>
6878
6879<div style="margin: auto;">
6880  <h3><a class="anchor" id="seed"></a>-seed</h3>
6881</div>
6882
6883<p class="magick-description">seed a new sequence of pseudo-random numbers</p>
6884
6885<div style="margin: auto;">
6886  <h3><a class="anchor" id="segment"></a>-segment <var>cluster-threshold</var>x<var>smoothing-threshold</var></h3>
6887</div>
6888
6889<p class="magick-description">segment the colors of an image.</p>
6890
6891<p>Segment an image by analyzing the histograms of the color components and
6892identifying units that are homogeneous with the fuzzy c-means technique. This
6893is part of the ImageMagick color quantization routines. </p>
6894
6895<p>Specify <var>cluster threshold</var> as the number of pixels in
6896each cluster that must exceed the cluster threshold to be considered valid.
6897<var>Smoothing threshold</var> eliminates noise in the second
6898derivative of the histogram. As the value is increased, you can expect
6899a smoother second derivative.  The default is 1.5.</p>
6900
6901<p>If the <a href="command-line-options.html#verbose">-verbose</a> setting is defined, a detailed report
6902of the color clusters is returned.</p>
6903
6904
6905<div style="margin: auto;">
6906  <h3><a class="anchor" id="selective-blur"></a>-selective-blur <var>radius</var><br />-selective-blur <var>radius</var>x<var>sigma</var>{<var>+threshold</var>}</h3>
6907</div>
6908
6909<p class="magick-description">Selectively blur pixels within a contrast threshold.</p>
6910
6911<p>Blurs those pixels that are less than or equal to the threshold in
6912contrast. The threshold may be expressed as a fraction of <var>QuantumRange</var> or as a percentage.</p>
6913
6914<div style="margin: auto;">
6915  <h3><a class="anchor" id="separate"></a>-separate</h3>
6916</div>
6917
6918<p class="magick-description">separate an image channel into a grayscale image.  Specify the channel with <a href="command-line-options.html#channel">-channel</a>.</p>
6919
6920<div style="margin: auto;">
6921  <h3><a class="anchor" id="sepia-tone"></a>-sepia-tone <var>percent-threshold</var></h3>
6922</div>
6923
6924<p class="magick-description">simulate a sepia-toned photo.</p>
6925
6926<p>Specify <var>threshold</var> as the percent threshold of the intensity (0 - 99.9%).</p>
6927
6928<p>This option applies a special effect to the image, similar to the effect
6929achieved in a photo darkroom by sepia toning.  Threshold ranges from 0 to <var>QuantumRange</var> and is a measure of the extent of the sepia
6930toning.  A threshold of 80% is a good starting point for a reasonable
6931tone.</p>
6932
6933
6934
6935<div style="margin: auto;">
6936  <h3><a class="anchor" id="set"></a>-set <var>key value</var></h3>
6937  <h3>+set <var>key</var></h3>
6938</div>
6939
6940<p class="magick-description">sets image attributes and properties for images in the current image sequence.</p>
6941
6942<p>This will assign (or modify) specific settings attached to all the images
6943in the current image sequence.  Using the <a href="command-line-options.html#set">+set</a> form of the
6944option will either remove, or reset that setting to a default state, as
6945appropriate.  </p>
6946
6947<p>For example, it will modify specific well known image meta-data
6948'attributes' such as those normally overridden by: the options <a
6949href="command-line-options.html#delay" >-delay</a>, <a href="command-line-options.html#dispose" >-dispose</a>, and <a
6950href="command-line-options.html#page" >-page</a>, <a href="command-line-options.html#colorspace" >-colorspace</a>; generally
6951assigned before the image is read in, by using a <var>key</var> of
6952the same name. </p>
6953
6954<p>If the given <var>key</var> does not match a specific known
6955'attribute ', such as shown above, the setting is stored as a a free form
6956'property' string.  Such settings are listed in <a href="command-line-options.html#verbose"
6957>-verbose</a> information ("<code>info:</code>" output format) as "Properties".
6958</p>
6959
6960<p>This includes string 'properties' that are set by and assigned to images
6961using the options <a href="command-line-options.html#comment" >-comment</a>, <a href="command-line-options.html#label"
6962>-label</a>, <a href="command-line-options.html#caption" >-caption</a>. These options actually assign
6963a global 'artifact' which are automatically assigned (and any <a href="../www/escape.html" >Format Percent
6964Escapes</a> expanded) to images as they are read in.  For example:</p>
6965
6966<pre class="highlight"><code>-> convert rose: -set comment 'Rose is a rose is a rose is a rose' rose.png
6967identify -format %c rose.png
6968Rose is a rose is a rose is a rose
6969</code></pre>
6970
6971<p>The set value can also make use of <a href="../www/escape.html" >Format and Print Image
6972Properties</a> in the defined value.  For example:</p>
6973
6974<pre class="highlight"><code>-> convert rose: -set origsize '%wx%h' -resize 50% \
6975  -format 'Old size = %[origsize]  New size = %wx%h' info:
6976Old size = 70x46  New size = 35x23
6977</code></pre>
6978
6979<p>Other well known 'properties' that are available include:
6980'<code>date:create</code>' and '<code>date:modify</code>' and
6981'<code>signature</code>'. </p>
6982
6983<p>The <a href="command-line-options.html#repage">-repage</a> operator will also allow you to modify
6984the '<code>page</code>' attribute of an image for images already in memory (also
6985see <a href="command-line-options.html#repage">-page</a>).  However it is designed to provide a finer
6986control of the sub-parts of this 'attribute'. The <a href="command-line-options.html#set">-set page</a>
6987option will only provide a direct, unmodified assignment of  '<code>page</code>'
6988attribute. </p>
6989
6990<p>This option can also associate a colorspace or profile with your image.
6991For example,</p>
6992
6993<pre class="highlight"><code>convert image.psd -set profile ISOcoated_v2_eci.icc image-icc.psd
6994</code></pre>
6995
6996<p>Some 'properties' must be defined in a specific way to be used. For
6997example only 'properties' prefixed with "<code>filename:</code>" can be used to
6998modify the output filename of an image. For example</p>
6999
7000<pre class="highlight"><code>convert rose: -set filename:mysize '%wx%h' 'rose_%[filename:mysize].png'
7001</code></pre>
7002
7003<p>If the setting value is prefixed with "<code>option:</code>" the setting will
7004be saved as a global "Artifact" exactly as if it was set using the <a
7005href="command-line-options.html#define" >-define</a> option. As such settings are global in scope, they
7006can be used to pass 'attributes' and 'properties' of one specific image,
7007in a way that allows you to use them in a completely different image, even if
7008the original image has long since been modified or destroyed. For example: </p>
7009
7010<pre class="highlight"><code>convert rose:  -set option:rosesize '%wx%h' -delete 0 \
7011  label:'%[rosesize]'   label_size_of_rose.gif"
7012</code></pre>
7013
7014<p>Note that <a href="../www/escape.html" >Format Percent Escapes</a> will only match
7015a 'artifact' if the given <var>key</var> does not match an existing
7016'attribute' or 'property'.  </p>
7017
7018<p>You can set the attributes of the image registry by prefixing the value
7019with <code>registry:</code>.</p>
7020
7021<p>The <a href="command-line-options.html#set">-set profile</a> option can also be used to inject
7022previously-formatted ancillary chunks into the output PNG file, using
7023the commandline option as shown below or by setting the profile via a
7024programming interface:</p>
7025
7026<pre class="highlight"><code>convert in.png -set profile PNG-chunk-x:&lt;filename&gt; out.png
7027</code></pre>
7028
7029<p>where <var>x</var> is a location flag and
7030<var>filename</var> is a file containing the chunk
7031name in the first 4 bytes, then a colon (":"), followed by the chunk data.
7032This encoder will compute the chunk length and CRC, so those must not
7033be included in the file.</p>
7034
7035<p>"x" can be "b" (before PLTE), "m" (middle, i.e., between PLTE and IDAT),
7036or "e" (end, i.e., after IDAT).  If you want to write multiple chunks
7037of the same type, then add a short unique string after the "x" to prevent
7038subsequent profiles from overwriting the preceding ones, e.g.,</p>
7039
7040
7041<pre class="highlight"><code>convert in.png -set profile PNG-chunk-b01:file01 \
7042  -profile PNG-chunk-b02:file02 out.png
7043</code></pre>
7044
7045<div style="margin: auto;">
7046  <h3><a class="anchor" id="shade"></a>-shade <var>azimuth</var>x<var>elevation</var></h3>
7047</div>
7048
7049<p class="magick-description">shade the image using a distant light source.</p>
7050
7051<p>Specify <var>azimuth</var> and <var>elevation</var> as
7052the position of the light source. Use <a href="command-line-options.html#shade">+shade</a> to return
7053the shading results as a grayscale image.</p>
7054
7055<div style="margin: auto;">
7056  <h3><a class="anchor" id="shadow"></a>-shadow <var>percent-opacity</var>{x<var>sigma</var>}{<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var>{<var>%</var>}</h3>
7057</div>
7058
7059<p class="magick-description">simulate an image shadow.</p>
7060
7061<div style="margin: auto;">
7062  <h3><a
7063id="shared-memory"></a>-shared-memory</h3>
7064</div>
7065
7066<p class="magick-description">use shared memory.</p>
7067
7068<p>This option specifies whether the utility should attempt to use shared
7069memory for pixmaps. ImageMagick must be compiled with shared memory support,
7070and the display must support the <var>MIT-SHM</var> extension.
7071Otherwise, this option is ignored. The default is <code>True</code>.</p>
7072
7073<div style="margin: auto;">
7074  <h3><a class="anchor" id="sharpen"></a>-sharpen <var>radius</var><br />-sharpen <var>radius</var>x<var>sigma</var></h3>
7075</div>
7076
7077<p class="magick-description">sharpen the image.</p>
7078
7079<p>Use a Gaussian operator of the given radius and standard deviation (sigma).</p>
7080
7081<div style="margin: auto;">
7082  <h3><a class="anchor" id="shave"></a>-shave <var>geometry</var></h3>
7083</div>
7084
7085<p class="magick-description">Shave pixels from the image edges.</p>
7086
7087<p>The <var>size</var> portion of the <var>geometry</var>
7088argument specifies the width of the region to be removed from both sides of
7089the image and the height of the regions to be removed from top and bottom.
7090Offsets are ignored.</p>
7091
7092<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7093
7094<div style="margin: auto;">
7095  <h3><a class="anchor" id="shear"></a>-shear <var>Xdegrees</var>[x<var>Ydegrees</var>]</h3>
7096</div>
7097
7098<p class="magick-description">Shear the image along the x-axis and/or y-axis.</p>
7099
7100<p>The shear angles may be positive, negative, or zero. When <var>Ydegrees</var> is omitted it defaults to 0. When both angles are
7101given, the horizontal component of the shear is performed before the vertical
7102component.</p>
7103
7104<p>Shearing slides one edge of an image along the x-axis or y-axis (i.e.,
7105horizontally or vertically, respectively),creating a parallelogram. The amount
7106of each is controlled by the respective shear angle. For horizontal shears,
7107<var>Xdegrees</var> is measured clockwise relative to "up" (the
7108negative y-axis), sliding the top edge to the right when 0°&lt;<var>Xdegrees</var>&lt;90° and to the left when 90°&lt;<var>Xdegrees</var>&lt;180°.  For vertical shears <var>Ydegrees</var> is measured clockwise relative to "right" (the
7109positive x-axis), sliding the right edge down when 0°&lt;<var>Ydegrees</var>&lt;90° and up when 90°&lt;<var>Ydegrees</var>&lt;180°.</p>
7110
7111<p>Empty triangles left over from shearing the image are filled with the color
7112defined by the <a href="command-line-options.html#fill">-background</a> option. The color is specified
7113using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7114
7115<p>The horizontal shear is performed before the vertical part. This is
7116important to note, since horizontal and vertical shears do not
7117<var>commute</var>, i.e., the order matters in a sequence of shears. For
7118example, the following two commands are not equivalent.</p>
7119
7120<pre class="highlight"><code>convert logo: -shear 20x0 -shear 0x60 logo-sheared.png
7121convert logo: -shear 0x60 -shear 20x0 logo-sheared.png
7122</code></pre>
7123
7124<p>The first of the two commands above is equivalent to the following, except
7125for the amount of empty space created; the command that follows generates
7126a smaller image, and so is a better choice in terms of time and space.</p>
7127
7128<pre class="highlight"><code>convert logo: -shear 20x60 logo-sheared.png
7129</code></pre>
7130
7131<div style="margin: auto;">
7132  <h3><a class="anchor" id="sigmoidal-contrast"></a>-sigmoidal-contrast <var>contrast</var>x<var>mid-point</var></h3>
7133</div>
7134
7135<p class="magick-description">increase the contrast without saturating highlights or shadows.</p>
7136
7137<p>Increase the contrast of the image using a sigmoidal transfer function
7138without saturating highlights or shadows. <var>Contrast</var>
7139indicates how much to increase the contrast. For example, 0 is none, 3 is
7140typical and 20 is a lot.
7141</p>
7142
7143<p>The <var>mid-point</var> indicates where the maximum change
7144'slope' in contrast should fall in the resultant image (0 is white; 50% is
7145middle-gray; 100% is black). </p>
7146
7147<p>By default the image contrast is increased, use <var>+sigmoidal-contrast</var> to decrease the contrast.</p>
7148
7149<p>To achieve the equivalent of a sigmoidal brightness change (similar to
7150a gamma adjustment), you would use <var>-sigmoidal-contrast
7151{brightness}x0%</var> to increase brightness and <var>+sigmoidal-contrast {brightness}x0%</var> to decrease brightness.
7152Note the use of '0' fo rthe mid-point of the sigmoidal curve. </p>
7153
7154<p>Using a very high <var>contrast</var> will produce a sort of
7155'smoothed thresholding' of the image.  Not as sharp (with high aliasing
7156effects) of a true threshold, but with tapered gray-levels around the threshold
7157<var>mid-point</var>. </p>
7158
7159<div style="margin: auto;">
7160  <h3><a class="anchor" id="silent"></a>-silent</h3>
7161
7162
7163</div>
7164
7165<p class="magick-description">operate silently. This option is only used
7166by the <a href="import.html">import</a> tool.</p>
7167
7168<div style="margin: auto;">
7169  <h3><a class="anchor" id="similarity-threshold"></a>-similarity-threshold <var>value</var></h3>
7170</div>
7171
7172<p class="magick-description">minimum RMSE for subimage match.</p>
7173
7174<p>If this setting is used, then the search will stop as soon as it finds a match whose metric is less than or equal to the value. A partially filled second output image will result. Using a value of zero, will cause the search to stop at the first perfect match it finds. If this setting is left off, then the search will proceed to completion or as limited by <var>-dissimilarity-threshold</var>.</p>
7175
7176<div style="margin: auto;">
7177  <h3><a class="anchor" id="size"></a>-size <var>width</var>[x<var>height</var>][<var>+offset</var>]</h3>
7178</div>
7179
7180<p class="magick-description">set the width and height of the image.</p>
7181
7182<p>Use this option to specify the width and height of raw images whose
7183dimensions are unknown such as <code>GRAY</code>, <code>RGB</code>, or
7184<code>CMYK</code>. In addition to width and height, use <a
7185href="command-line-options.html#size">-size</a> with an offset to skip any header information in the
7186image or tell the number of colors in a <code>MAP</code> image file, (e.g. -size
7187640x512+256).</p>
7188
7189<p>For Photo CD images, choose from these sizes:</p>
7190
7191<pre class="highlight"><code>192x128
7192384x256
7193768x512
71941536x1024
71953072x2048
7196</code></pre>
7197
7198<div style="margin: auto;">
7199  <h3><a class="anchor" id="sketch"></a>-sketch <var>radius</var><br />-sketch <var>radius</var>x<var>sigma</var>+<var>angle</var></h3>
7200</div>
7201
7202<p class="magick-description">simulate a pencil sketch.</p>
7203
7204<p>Sketch with the given radius, standard deviation (sigma), and angle.   The
7205angle given is the angle toward which the image is sketched.  That is the
7206direction people would consider the object is coming from.  </p>
7207
7208<div style="margin: auto;">
7209  <h3><a class="anchor" id="smush"></a>-smush <var>offset</var></h3>
7210</div>
7211
7212<p class="magick-description">appends an image sequence together ignoring transparency.</p>
7213
7214<p>Smush is a more flexible version of <a href="command-line-options.html#append">-append</a>, joining the images in the sequence top-to-bottom (<a href="command-line-options.html#smush">-smush</a>) or left-to-right (<a href="command-line-options.html#smush">+smush</a>), with a gap between images according to the specified offset.</p>
7215
7216<p>If the offset is negative, images will overlap by that amount.</p>
7217
7218<p><a href="command-line-options.html#smush">-smush</a> respects <a href="command-line-options.html#gravity">-gravity</a>. Any empty space will be filled with the <a href="command-line-options.html#background">-background</a> color.</p>
7219
7220<p>For zero offset and transparent images, the non-transparent parts of the two images will be aligned as close as possible without overlapping.</p>
7221
7222<div style="margin: auto;">
7223  <h3><a class="anchor" id="snaps"></a>-snaps <var>value</var></h3>
7224</div>
7225
7226<p class="magick-description">Set the number of screen snapshots.</p>
7227
7228<p>Use this option to grab more than one image from the X server screen, to create an animation sequence.</p>
7229
7230<div style="margin: auto;">
7231  <h3><a class="anchor" id="solarize"></a>-solarize <var>percent-threshold</var></h3>
7232</div>
7233
7234<p class="magick-description">negate all pixels above the threshold level.</p>
7235
7236<p>Specify <var>factor</var> as the percent threshold of the intensity (0 - 99.9%).</p>
7237
7238<p>This option produces a <var>solarization</var> effect seen when
7239exposing a photographic film to light during the development process.</p>
7240
7241<div style="margin: auto;">
7242  <h3><a class="anchor" id="sparse-color"></a>-sparse-color <var>method</var>  '<var>x</var>,<var>y</var> <var>color</var>  ...'</h3>
7243</div>
7244
7245<p class="magick-description"> color the given image using the specified points of color, and filling the other intervening colors using the given methods. </p>
7246
7247
7248<dl class="row">
7249    <dt class="col-md-4">barycentric</dt>
7250    <dd class="col-md-8">three point triangle of color given 3 points.
7251        Giving only 2 points will form a linear gradient between those points.
7252        The gradient generated extends beyond the triangle created by those
7253        3 points. </dd>
7254    <dt class="col-md-4">bilinear</dt>
7255    <dd class="col-md-8">Like barycentric but for 4 points. Less than 4 points
7256        fall back to barycentric. </dd>
7257    <dt class="col-md-4">voronoi</dt>
7258    <dd class="col-md-8">Simply map each pixel to the to nearest color point
7259        given. The result are polygonal 'cells' of solid color. </dd>
7260    <dt class="col-md-4">manhattan</dt>
7261    <dd class="col-md-8">Like voronoi, but resulting polygonal 'cells' are mapped to a fixed coordinate system.</dd>
7262    <dt class="col-md-4">shepards</dt>
7263    <dd class="col-md-8">Colors points biased on the ratio of inverse distance
7264        squared. Generating spots of color in a sea of the average of
7265        colors. </dd>
7266    <dt class="col-md-4">inverse</dt>
7267    <dd class="col-md-8">Colors points biased on the ratio of inverse distance.
7268        This generates sharper points of color rather than rounded spots of
7269        '<code>shepards</code>'  Generating spots of color in a sea of the
7270        average of colors. </dd>
7271</dl>
7272
7273<p>The points are placed according to the images location on the virtual
7274canvas (<a href="command-line-options.html#page" >-page</a> or <a href="command-line-options.html#repage" >-repage</a>
7275offset), and do not actually have to exist on the given image, but may be
7276some point beyond the edge of the image. All points are floating point values.
7277</p>
7278
7279<p>Only the color channels defined by the <a href="command-line-options.html#channel" >-channel</a> are
7280modified, which means that by default matte/alpha transparency channel is not
7281affected. Typically transparency channel is turned off either before or after
7282the operation. </p>
7283
7284<p>Of course if some color points are transparent to generate a transparent
7285gradient, then the image also requires transparency enabled to store the
7286values. </p>
7287
7288<p>All the above methods when given a single point of color will replace all
7289the colors in the image with the color given, regardless of the point. This is
7290logical, and provides an alternative technique to recolor an image to some
7291default value. </p>
7292
7293
7294<div style="margin: auto;">
7295  <h3><a class="anchor" id="splice"></a>-splice <var>geometry</var></h3>
7296</div>
7297
7298<p class="magick-description">Splice the current background color into the image.</p>
7299
7300<p>This will add rows and columns of the current <a
7301href="command-line-options.html#background">-background</a> color into the given image according to the
7302given  <a href="command-line-options.html#gravity">-gravity</a> geometry setting.  See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Essentially <a href="command-line-options.html#splice">-splice</a> will divide the
7303image into four quadrants, separating them by the inserted rows and columns.
7304</p>
7305
7306<p>If a dimension of geometry is zero no rows or columns will be added for that
7307dimension.  Similarly using a zero offset with the appropriate <a
7308href="command-line-options.html#gravity">-gravity</a> setting will add rows and columns to the edges of
7309the image, padding the image only along that one edge. Edge padding is what <a
7310href="command-line-options.html#splice">-splice</a> is most commonly used for. </p>
7311
7312<p>If the exact same  <var>geometry</var> and <a
7313href="command-line-options.html#gravity">-gravity</a> is later used with <a href="command-line-options.html#chop">-chop</a> the
7314added added all splices removed. </p>
7315
7316<div style="margin: auto;">
7317  <h3><a class="anchor" id="spread"></a>-spread <var>amount</var></h3>
7318</div>
7319
7320<p class="magick-description">displace image pixels by a random amount.</p>
7321
7322<p>The argument <var>amount</var> defines the size of the
7323neighborhood around each pixel from which to choose a candidate pixel to
7324blend.</p>
7325
7326<p>The lookup is controlled by the <a href="command-line-options.html#interpolate">-interpolate</a> setting.</p>
7327
7328<div style="margin: auto;">
7329  <h3><a class="anchor" id="statistic"></a>-statistic <var>type</var> <var>geometry</var></h3>
7330</div>
7331
7332<p class="magick-description">replace each pixel with corresponding statistic from the neighborhood.</p>
7333
7334<p>Choose from these statistic types:</p>
7335<dl class="row">
7336<dt class="col-md-4">Gradient</dt><dd class="col-md-8">maximum difference (max - min) value in neighborhood</dd>
7337<dt class="col-md-4">Maximum</dt><dd class="col-md-8">maximum value per channel in neighborhood</dd>
7338<dt class="col-md-4">Minimum</dt><dd class="col-md-8">minimum value per channel in neighborhood</dd>
7339<dt class="col-md-4">Mean</dt><dd class="col-md-8">average value per channel in neighborhood</dd>
7340<dt class="col-md-4">Median</dt><dd class="col-md-8">median value per channel in neighborhood</dd>
7341<dt class="col-md-4">Mode</dt><dd class="col-md-8">mode (most frequent) value per channel in neighborhood</dd>
7342<dt class="col-md-4">Nonpeak</dt><dd class="col-md-8">value just before or after the median value per channel in neighborhood</dd>
7343<dt class="col-md-4">RMS</dt><dd class="col-md-8">root mean square value per channel in neighborhood</dd>
7344<dt class="col-md-4">StandardDeviation</dt><dd class="col-md-8"> standard deviation value per channel in neighborhood</dd>
7345</dl>
7346
7347<div style="margin: auto;">
7348  <h3><a class="anchor" id="stegano"></a>-stegano <var>offset</var></h3>
7349</div>
7350
7351<p class="magick-description">hide watermark within an image.</p>
7352
7353<p>Use an offset to start the image hiding some number of pixels from the
7354beginning of the image. Note this offset and the image size. You will need
7355this information to recover the steganographic image (e.g. display -size
7356320x256+35 stegano:image.png).</p>
7357
7358<div style="margin: auto;">
7359  <h3><a class="anchor" id="stereo"></a>-stereo <var>+x</var>{<var>+y</var>}</h3>
7360</div>
7361
7362<p class="magick-description">composite two images to create a red / cyan stereo anaglyph.</p>
7363
7364<p>The left side of the stereo pair (second image) is saved as the red channel of the output image. The right side (first image) is saved as the green and blue channels. Red-green stereo glasses are required to properly view the stereo image.</p>
7365
7366<div style="margin: auto;">
7367  <h3><a class="anchor" id="storage-type"></a>-storage-type <var>type</var></h3>
7368</div>
7369
7370<p class="magick-description">pixel storage type.  Here are the valid types:</p>
7371
7372<dl class="row">
7373<dt class="col-md-4">char</dt><dd class="col-md-8">unsigned characters</dd>
7374<dt class="col-md-4">double</dt><dd class="col-md-8">doubles</dd>
7375<dt class="col-md-4">float</dt><dd class="col-md-8">floats</dd>
7376<dt class="col-md-4">integer</dt><dd class="col-md-8">integers</dd>
7377<dt class="col-md-4">long</dt><dd class="col-md-8">longs</dd>
7378<dt class="col-md-4">quantum</dt><dd class="col-md-8">pixels in the native depth of your ImageMagick distribution</dd>
7379<dt class="col-md-4">short</dt><dd class="col-md-8">unsigned shorts</dd>
7380</dl>
7381
7382<p>Float and double types are normalized from 0.0 to 1.0 otherwise the pixels
7383values range from 0 to the maximum value the storage type can support.</p>
7384
7385<div style="margin: auto;">
7386  <h3><a class="anchor" id="stretch"></a>-stretch <var>fontStretch</var></h3>
7387</div>
7388
7389<p class="magick-description">Set a type of stretch style for fonts.</p>
7390
7391<p>This setting suggests a type of stretch that ImageMagick should try to
7392apply to the currently selected font family. Select <var>fontStretch</var> from the following.</p>
7393
7394<pre class="highlight"><code>Any
7395Condensed
7396Expanded
7397ExtraCondensed
7398ExtraExpanded
7399Normal
7400SemiCondensed
7401SemiExpanded
7402UltraCondensed
7403UltraExpanded
7404</code></pre>
7405
7406<p>To print a complete list of stretch types, use <a href="command-line-options.html#list">-list
7407stretch</a>.</p>
7408
7409<p>For other settings that affect fonts, see the options <a
7410href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
7411href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
7412
7413<div style="margin: auto;">
7414  <h3><a class="anchor" id="strip"></a>-strip</h3>
7415</div>
7416
7417<p class="magick-description">strip the image of any profiles, comments or these PNG chunks: bKGD,cHRM,EXIF,gAMA,iCCP,iTXt,sRGB,tEXt,zCCP,zTXt,date.</p>
7418
7419<div style="margin: auto;">
7420  <h3><a class="anchor" id="stroke"></a>-stroke <var>color</var></h3>
7421</div>
7422
7423<p class="magick-description">color to use when stroking a graphic primitive.</p>
7424
7425<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7426
7427<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7428
7429<div style="margin: auto;">
7430  <h3><a class="anchor" id="strokewidth"></a>-strokewidth <var>value</var></h3>
7431</div>
7432
7433<p class="magick-description">set the stroke width.</p>
7434
7435<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7436
7437<div style="margin: auto;">
7438  <h3><a class="anchor" id="style"></a>-style <var>fontStyle</var></h3>
7439</div>
7440
7441<p class="magick-description">Set a font style for text.</p>
7442
7443<p>This setting suggests a font style that ImageMagick should try to apply to
7444the currently selected font family. Select <var>fontStyle</var> from
7445the following.</p>
7446
7447<pre class="highlight"><code>Any
7448Italic
7449Normal
7450Oblique
7451</code></pre>
7452
7453<p>For other settings that affect fonts, see the options <a
7454href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
7455href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
7456
7457<div style="margin: auto;">
7458  <h3><a class="anchor" id="subimage-search"></a>-subimage-search</h3>
7459</div>
7460
7461<p class="magick-description">search for subimage.</p>
7462
7463<p>This option is required to have compare search for the best match location
7464of a small image within a larger image. This search will produce two images
7465(or two frames). The first is the "difference" image and the second will
7466be the "match score" image.</p>
7467
7468<p>The "match-score" image is smaller containing a pixel for ever possible
7469position of the top-left corner of the given sub-image. that is its size will
7470be the size of the larger_image - sub_image + 1.  The brightest location in
7471this image is the location s the locate on the best match that is also
7472reported. Note that this may or may not be a perfect match, and the actual
7473brightness will reflect this. Other bright 'peaks' can be used to locate other
7474possible matching locations. </p>
7475
7476<p>Note that the search will try to compare the sub-image at every possible
7477location in the larger image, as such it can be very slow.  The smaller the
7478sub-image the faster this search is. </p>
7479
7480
7481<div style="margin: auto;">
7482  <h3><a class="anchor" id="swap"></a>-swap <var>index,index</var></h3>
7483</div>
7484
7485<p class="magick-description">Swap the positions of two images in the image sequence.</p>
7486
7487<p>For example, <a href="command-line-options.html#swap">-swap 0,2</a> swaps the first and the third
7488images in the current image sequence. Use <a href="command-line-options.html#swap">+swap</a> to switch
7489the last two images in the sequence.</p>
7490
7491<div style="margin: auto;">
7492  <h3><a class="anchor" id="swirl"></a>-swirl <var>degrees</var></h3>
7493</div>
7494
7495<p class="magick-description">swirl image pixels about the center.</p>
7496
7497<p><var>Degrees</var> defines the tightness of the swirl.</p>
7498
7499<div style="margin: auto;">
7500  <h3><a class="anchor" id="synchronize"></a>-synchronize</h3>
7501</div>
7502
7503<p class="magick-description">synchronize image to storage device.</p>
7504
7505<p>Set to "true" to ensure all image data is fully flushed and synchronized
7506to disk. There is a performance penalty, but the benefits include ensuring a
7507valid image file in the event of a system crash and early reporting if there
7508is not enough disk space for the image pixel cache.</p>
7509
7510<div style="margin: auto;">
7511  <h3><a class="anchor" id="taint"></a>-taint</h3>
7512</div>
7513
7514<p class="magick-description">Mark the image as modified.</p>
7515
7516<div style="margin: auto;">
7517  <h3><a class="anchor" id="text-font"></a>-text-font <var>name</var></h3>
7518</div>
7519
7520<p class="magick-description">font for writing fixed-width text.</p>
7521
7522<p>Specifies the name of the preferred font to use in fixed (typewriter style)
7523formatted text. The default is 14 point <var>Courier</var>.</p>
7524
7525<p>You can tag a font to specify whether it is a PostScript, TrueType, or
7526OPTION1 font. For example, <code>Courier.ttf</code> is a TrueType font and
7527<code>x:fixed</code> is OPTION1.</p>
7528
7529<div style="margin: auto;">
7530  <h3><a class="anchor" id="texture"></a>-texture <var>filename</var></h3>
7531</div>
7532
7533<p class="magick-description">name of texture to tile onto the image background.</p>
7534
7535<div style="margin: auto;">
7536  <h3><a class="anchor" id="threshold"></a>-threshold <var>value</var>{<var>%</var>}</h3>
7537</div>
7538
7539<!-- {<var>green,blue,opacity</var>}
7540<p>If the green or blue value is omitted, these channels use the same value as
7541the first one provided. If all three color values are the same, the result is
7542a bi-level image. If the opacity threshold is omitted, OpaqueOpacity is used
7543and any partially transparent pixel becomes fully transparent.</p>
7544-->
7545
7546<p class="magick-description">Apply simultaneous black/white threshold to the image.</p>
7547
7548<p>Any pixel values (more specifically, those channels set using <a href="command-line-options.html#channel">&#x2011;channel</a>) that exceed the specified threshold are reassigned the
7549maximum channel value, while all other values are assigned the minimum.</p>
7550
7551<p> The threshold value can be given as a percentage or as an absolute integer
7552value corresponding to the desired channel value. When given as an integer,
7553the minimum attainable value is 0 (corresponding to black when all channels
7554are affected), but the maximum value (corresponding to white) is that of the
7555<code>quantum depth</code> of the particular build of ImageMagick, and is
7556therefore dependent on the installation. For that reason, a reasonable
7557recommendation for most applications is to specify the threshold values as
7558a percentage.  </p>
7559
7560<p> The following would force pixels with red values above 50% to have 100%
7561red values, while those at or below 50% red would be set to 0 in the red
7562channel. The green, blue, and alpha channels (if present) would be unchanged.
7563</p>
7564
7565<pre class="highlight"><code>convert in.png -channel red -threshold 50% out.png
7566</code></pre>
7567
7568<p>As (possibly) impractical but instructive examples, the following would
7569generate an all-black and an all-white image with the same dimensions as the
7570input image.</p>
7571
7572
7573<pre class="highlight"><code>convert in.png -channel RGB -threshold 100% black.png
7574convert in.png -channel RGB -threshold -1 white.png
7575</code></pre>
7576
7577<p> See also <a href="command-line-options.html#black-threshold">&#x2011;black&#x2011;threshold</a> and <a href="command-line-options.html#white-threshold">&#x2011;white&#x2011;threshold</a>.
7578</p>
7579
7580<div style="margin: auto;">
7581  <h3><a class="anchor" id="thumbnail"></a>-thumbnail <var>geometry</var></h3>
7582</div>
7583
7584<p class="magick-description">Create a thumbnail of the image.</p>
7585
7586<p>This is similar to <a href="command-line-options.html#resize">-resize</a>, except it is optimized
7587for speed and any image profile, other than a color profile, is removed to
7588reduce the thumbnail size.  To strip the color profiles as well, add <a
7589href="command-line-options.html#strip">-strip</a> just before of after this option.</p>
7590
7591<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7592
7593<div style="margin: auto;">
7594  <h3><a class="anchor" id="tile"></a>-tile <var>filename</var></h3>
7595</div>
7596
7597<p class="magick-description">Set the tile image used for filling a subsequent graphic primitive.</p>
7598
7599<div style="margin: auto;">
7600  <h3>-tile <var>geometry</var></h3>
7601</div>
7602
7603<p class="magick-description">Specify the layout of images.</p>
7604
7605<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7606
7607<div style="margin: auto;">
7608  <h3>-tile</h3>
7609</div>
7610
7611<p class="magick-description">Specifies that a subsequent composite operation is repeated across and down image.</p>
7612
7613<div style="margin: auto;">
7614  <h3><a class="anchor" id="tile-offset"></a>-tile-offset {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h3>
7615</div>
7616
7617<p class="magick-description">Specify the offset for tile images, relative to the background image it is tiled on.</p>
7618
7619<p>This should be set before the tiling image is set by <a href="command-line-options.html#tile"
7620>-tile</a> or <a href="command-line-options.html#texture" >-texture</a>, or directly applied for
7621creating a tiled canvas using <code>TILE:</code> or <code>PATTERN:</code> input
7622formats. </p>
7623
7624<p>Internally ImageMagick does a <a href="command-line-options.html#roll" >-roll</a> of the tile image
7625by the arguments given when the tile image is set. </p>
7626
7627<div style="margin: auto;">
7628  <h3><a class="anchor" id="tint"></a>-tint <var>value</var></h3>
7629</div>
7630
7631<p class="magick-description">Tint the image with the fill color.</p>
7632
7633<p>Tint the image with the fill color.</p>
7634
7635<p>Specify the amount of tinting as a percentage.  Pure colors like black,
7636white red, yellow, will not be affected by -tint. Only mid-range colors such
7637as the various shades of grey.</p>
7638
7639<div style="margin: auto;">
7640  <h3><a class="anchor" id="title"></a>-title <var>string</var></h3>
7641</div>
7642
7643<p class="magick-description">Assign a title to displayed image.", "animate", "display", "montage</p>
7644
7645<p>Use this option to assign a specific title to the image. This assigned to
7646the image window and is typically displayed in the window title bar.
7647Optionally you can include the image filename, type, width, height, Exif data,
7648or other image attribute by embedding special format characters described
7649under the <a href="command-line-options.html#format">-format</a> option.</p>
7650
7651<p>For example,</p>
7652
7653<pre class="highlight"><code>-title "%m:%f %wx%h"
7654</code></pre>
7655
7656<p>produces an image title of <code>MIFF:bird.miff 512x480</code> for an image
7657titled <code>bird.miff</code> and whose width is 512 and height is 480.</p>
7658
7659
7660<div style="margin: auto;">
7661  <h3><a class="anchor" id="transform"></a>-transform</h3>
7662</div>
7663
7664<p class="magick-description">transform the image.</p>
7665
7666<p>This option applies the transformation matrix from a previous <a href="command-line-options.html#affine">-affine</a> option.</p>
7667
7668<pre class="highlight"><code>convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg
7669</code></pre>
7670
7671
7672<p>This operator has been now been superseded by the  <a
7673href="command-line-options.html#distort">-distort</a> '<code>AffineProjection</code>' method. </p>
7674
7675
7676<div style="margin: auto;">
7677  <h3><a class="anchor" id="transparent"></a>-transparent <var>color</var></h3>
7678</div>
7679
7680<p class="magick-description">Make this color transparent within the image.</p>
7681
7682<p>The <var>color</var> argument is defined using the format
7683described under the <a href="command-line-options.html#fill">-fill</a> option. The <a href="command-line-options.html#fuzz"
7684>-fuzz</a> setting can be used to match and replace colors similar to the one
7685given. </p>
7686
7687<p>Use  <a href="command-line-options.html#transparent" >+transparent</a> to invert the pixels matched.
7688that is make all non-matching colors transparent. </p>
7689
7690<p>The <a href="command-line-options.html#opaque">-opaque</a>  operator is exactly the same as <a
7691href="command-line-options.html#transparent" >-transparent</a> but replaces the matching color with the
7692current <a href="command-line-options.html#fill">-fill</a> color setting, rather than transparent.
7693However the <a href="command-line-options.html#transparent" >-transparent</a> operator also ensures
7694that the image has an alpha channel enabled, as per "<code><a href="command-line-options.html#alpha"
7695>-alpha</a> set</code>", and does not require you to modify the <a
7696href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
7697
7698<p>Note that this does not define the color as being the 'transparency color'
7699used for color-mapped image formats, such as GIF.  For that use <a
7700href="command-line-options.html#transparent-color" >-transparent-color</a> </p>
7701
7702
7703<div style="margin: auto;">
7704  <h3><a class="anchor" id="transparent-color"></a>-transparent-color <var>color</var></h3>
7705</div>
7706
7707<p class="magick-description">Set the transparent color.</p>
7708
7709<p>Sometimes this is used for saving to image formats such as
7710GIF and PNG8 which uses this color to represent boolean transparency.  This
7711does not make a color transparent, it only defines what color the transparent
7712color is in the color palette of the saved image. Use <a
7713href="command-line-options.html#transparent">-transparent</a> to make an opaque color transparent.</p>
7714
7715<p>This option allows you to have both an opaque visible color, as well as a
7716transparent color of the same color value without conflict.  That is, you can
7717use the same color for both the transparent and opaque color areas within an
7718image.  This, in turn, frees to you to select a transparent color that is
7719appropriate when an image is displayed by an application that does not handle a
7720transparent color index, while allowing ImageMagick to correctly handle images of this
7721type. </p>
7722
7723<p>The default transparent color is <code>#00000000</code>, which is fully transparent black.</p>
7724
7725<div style="margin: auto;">
7726  <h3><a class="anchor" id="transpose"></a>-transpose</h3>
7727</div>
7728
7729<p class="magick-description">Mirror the image along the top-left to bottom-right diagonal.</p>
7730
7731<p> This option mathematically transposes the pixel array.  It is equivalent to the sequence <code>-flip -rotate 90</code>.
7732</p>
7733
7734<div style="margin: auto;">
7735  <h3><a class="anchor" id="transverse"></a>-transverse</h3>
7736</div>
7737
7738<p class="magick-description">Mirror the image along the images bottom-left top-right diagonal.  Equivalent to the operations <code>-flop -rotate 90</code>.</p>
7739
7740
7741<div style="margin: auto;">
7742  <h3><a class="anchor" id="treedepth"></a>-treedepth <var>value</var></h3>
7743</div>
7744
7745<p class="magick-description">tree depth for the color reduction algorithm.</p>
7746
7747<p>Normally, this integer value is zero or one. A value of zero or one causes
7748the use of an optimal tree depth for the color reduction algorithm.</p>
7749
7750<p>An optimal depth generally allows the best representation of the source
7751image with the fastest computational speed and the least amount of memory.
7752However, the default depth is inappropriate for some images. To assure the
7753best representation, try values between 2 and 8 for this parameter.  Refer to
7754the <a href="../www/quantize.html"
7755>color reduction algorithm</a> for more details.</p>
7756
7757<p>The <a href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#monochrome">-monochrome</a>
7758option, or writing to an image format which requires color reduction, is
7759required for this option to take effect.</p>
7760
7761<div style="margin: auto;">
7762  <h3><a class="anchor" id="trim"></a>-trim</h3>
7763</div>
7764
7765<p class="magick-description">trim an image.</p>
7766
7767<p>This option removes any edges that are exactly the same color as the corner
7768pixels. Use <a href="command-line-options.html#fuzz">-fuzz</a> to make <a href="command-line-options.html#trim">-trim</a> remove
7769edges that are nearly the same color as the corner pixels.</p>
7770
7771<p>The page or virtual canvas information of the image is preserved allowing
7772you to extract the result of the <a href="command-line-options.html#trim">-trim</a> operation from the
7773image.  Use a <a href="command-line-options.html#repage">+repage</a> to remove the virtual canvas page
7774information if it is unwanted.</p>
7775
7776<p>If the trimmed image 'disappears' an warning is produced, and a special
7777single pixel transparent 'missed' image is returned, in the same way as when a
7778<a href="command-line-options.html#crop">-crop</a> operation 'misses' the image proper. </p>
7779
7780
7781<div style="margin: auto;">
7782  <h3><a class="anchor" id="type"></a>-type <var>type</var></h3>
7783</div>
7784
7785<p class="magick-description">the image type.</p> <p>Choose from: <code>Bilevel</code>,
7786<code>Grayscale</code>, <code>GrayscaleAlpha</code>, <code>Palette</code>,
7787<code>PaletteAlpha</code>, <code>TrueColor</code>, <code>TrueColorAlpha</code>,
7788<code>ColorSeparation</code>, or <code>ColorSeparationAlpha</code>.</p>
7789
7790<p>Normally, when a format supports different subformats such as grayscale and
7791truecolor, the encoder will try to choose an efficient subformat. The <a
7792href="command-line-options.html#type">-type</a> option can be used to override this behavior. For
7793example, to prevent a JPEG from being written in grayscale format even though
7794only gray pixels are present, use.</p>
7795
7796<pre class="highlight"><code>convert bird.png -type TrueColor bird.jpg
7797</code></pre>
7798
7799<p>Similarly, use <a href="command-line-options.html#type">-type TrueColorAlpha</a> to force the
7800encoder to write an alpha channel even though the image is opaque, if the
7801output format supports transparency.</p>
7802
7803<p>Use <a href="command-line-options.html#type">-type optimize</a> to ensure the image is written in the smallest possible file size.</p>
7804
7805<div style="margin: auto;">
7806  <h3><a class="anchor" id="undercolor"></a>-undercolor <var>color</var></h3>
7807</div>
7808
7809<p class="magick-description">set the color of the annotation bounding box.</p>
7810
7811<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7812
7813<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7814
7815
7816<div style="margin: auto;">
7817  <h3><a class="anchor" id="update"></a>-update <var>seconds</var></h3>
7818</div>
7819
7820<p class="magick-description">detect when image file is modified and redisplay.</p>
7821
7822<p>Suppose that while you are displaying an image the file that is currently
7823displayed is over-written.  <code>display</code> will automagically detect that
7824the input file has been changed and update the displayed image
7825accordingly.</p>
7826
7827
7828<div style="margin: auto;">
7829  <h3><a class="anchor" id="unique-colors"></a>-unique-colors</h3>
7830</div>
7831
7832<p class="magick-description">discard all but one of any pixel color.</p>
7833
7834
7835<div style="margin: auto;">
7836  <h3><a class="anchor" id="units"></a>-units <var>type</var></h3>
7837</div>
7838
7839<p class="magick-description">the units of image resolution.</p>
7840
7841<p>Choose from: <code>Undefined</code>, <code>PixelsPerInch</code>, or
7842<code>PixelsPerCentimeter</code>. This option is normally used in conjunction
7843with the <a href="command-line-options.html#density">-density</a> option.</p>
7844
7845
7846<div style="margin: auto;">
7847  <h3><a class="anchor" id="unsharp"></a>-unsharp <var>radius</var><br />-unsharp <var>radius</var>x<var>sigma</var>{<var>+gain</var>}{<var>+threshold</var>}</h3>
7848</div>
7849
7850<p class="magick-description">sharpen the image with an unsharp mask operator.</p>
7851
7852<p>The <a href="command-line-options.html#unsharp">-unsharp</a> option sharpens an image. The image is
7853convolved with a Gaussian operator of the given radius and standard deviation
7854(sigma). For reasonable results, radius should be larger than sigma. Use
7855a radius of 0 to have the method select a suitable radius.</p>
7856
7857<p>The parameters are:</p>
7858
7859<dl class="row">
7860<dt class="col-md-4">radius</dt>
7861<dd class="col-md-8">The radius of the Gaussian, in pixels,  not counting the center pixel (default 0).</dd>
7862<dt class="col-md-4">sigma</dt>
7863<dd class="col-md-8">The standard deviation of the Gaussian, in pixels (default 1.0).</dd>
7864<dt class="col-md-4">gain</dt>
7865<dd class="col-md-8">The fraction of the difference between the original and the blur image that is added back into the original (default 1.0).</dd>
7866<dt class="col-md-4">threshold</dt>
7867<dd class="col-md-8">The threshold, as a fraction of <var>QuantumRange</var>, needed to apply the difference amount (default 0.05).</dd>
7868</dl>
7869
7870<div style="margin: auto;">
7871  <h3><a class="anchor" id="verbose"></a>-verbose</h3>
7872</div>
7873
7874<p class="magick-description">print detailed information about the image when this option precedes the <a href="command-line-options.html#identify">-identify</a> option or <code>info:</code>.</p>
7875
7876
7877<div style="margin: auto;">
7878  <h3><a class="anchor" id="version"></a>-version</h3>
7879</div>
7880
7881<p class="magick-description">print ImageMagick version string and exit.</p>
7882
7883
7884<div style="margin: auto;">
7885  <h3><a class="anchor" id="view"></a>-view <var>string</var></h3>
7886</div>
7887
7888<p class="magick-description">FlashPix viewing parameters.</p>
7889
7890
7891<div style="margin: auto;">
7892  <h3><a class="anchor" id="vignette"></a>-vignette <var>radius</var>{x<var>sigma</var>}{<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var>{<var>%</var>}</h3>
7893</div>
7894
7895<p class="magick-description">soften the edges of the image in vignette style.</p>
7896
7897<p>The vignette effect rolloff is controlled by radiusxsigma. For nominal rolloff, this would be set to 0xsigma. A value of 0x0 will produce a circle/ellipse with no rolloff. The arguments x and y control the size of the circle. Larger values decrease the radii and smaller values increase the radii. Values of +0+0 will generate a circle/ellipse the same size as the image. The default values for x and y are 10% of the corresponding image dimension. Thus, the radii will be decreased by 10%, i.e., the diameters of the circle/ellipse will be 80% of the corresponding image dimension.</p>
7898
7899<div style="margin: auto;">
7900  <h3><a class="anchor" id="virtual-pixel"></a>-virtual-pixel <var>method</var></h3>
7901</div>
7902
7903<p class="magick-description">Specify contents of <var>virtual pixels</var>.</p>
7904
7905<p>This option defines what color source should be used if and when a color
7906lookup completely 'misses' the source image. The color(s) that appear to
7907surround the source image.  Generally this color is derived from the source
7908image, but could also be set to a specify background color. </p>
7909
7910<p>Choose from these methods:</p>
7911
7912<dl class="row">
7913<dt class="col-md-4">background</dt><dd class="col-md-8">the area surrounding the image is the background color</dd>
7914<dt class="col-md-4">black</dt><dd class="col-md-8">the area surrounding the image is black</dd>
7915<dt class="col-md-4">checker-tile</dt><dd class="col-md-8">alternate squares with image and background color</dd>
7916<dt class="col-md-4">dither</dt><dd class="col-md-8">non-random 32x32 dithered pattern</dd>
7917<dt class="col-md-4">edge</dt><dd class="col-md-8">extend the edge pixel toward infinity</dd>
7918<dt class="col-md-4">gray</dt><dd class="col-md-8">the area surrounding the image is gray</dd>
7919<dt class="col-md-4">horizontal-tile</dt><dd class="col-md-8">horizontally tile the image, background color above/below</dd>
7920<dt class="col-md-4">horizontal-tile-edge</dt><dd class="col-md-8">horizontally tile the image and replicate the side edge pixels</dd>
7921<dt class="col-md-4">mirror</dt><dd class="col-md-8">mirror tile the image</dd>
7922<dt class="col-md-4">random</dt><dd class="col-md-8">choose a random pixel from the image</dd>
7923<dt class="col-md-4">tile</dt><dd class="col-md-8">tile the image (default)</dd>
7924<dt class="col-md-4">transparent</dt><dd class="col-md-8">the area surrounding the image is transparent blackness</dd>
7925<dt class="col-md-4">vertical-tile</dt><dd class="col-md-8">vertically tile the image, sides are background color</dd>
7926<dt class="col-md-4">vertical-tile-edge</dt><dd class="col-md-8">vertically tile the image and replicate the side edge pixels</dd>
7927<dt class="col-md-4">white</dt><dd class="col-md-8">the area surrounding the image is white</dd>
7928</dl>
7929
7930<p>The default value is "edge".</p>
7931
7932<p>This most important for distortion operators such as <a href="command-line-options.html#distort"
7933>-distort</a>, <a href="command-line-options.html#implode" >-implode</a>, and <a href="command-line-options.html#fx" >-fx</a>.
7934However it also affects operations that may access pixels just outside the
7935image proper, such as <a href="command-line-options.html#convolve">-convolve</a>, <a
7936href="command-line-options.html#blur">-blur</a>, and <a href="command-line-options.html#sharpen">-sharpen</a>. </p>
7937
7938<p>To print a complete list of virtual pixel types, use the <a
7939href="command-line-options.html#list">-list virtual-pixel</a> option.</p>
7940
7941
7942<div style="margin: auto;">
7943  <h3><a class="anchor" id="visual"></a>-visual <var>type</var></h3>
7944</div>
7945
7946<p class="magick-description">Animate images using this X visual type.", 'animate', 'display'</p>
7947
7948<p>Choose from these visual classes:</p>
7949
7950<pre class="highlight"><code>StaticGray    TrueColor
7951GrayScale     DirectColor
7952StaticColor   default
7953PseudoColor   visual id
7954</code></pre>
7955
7956<p>The X server must support the visual you choose, otherwise an error occurs.
7957If a visual is not specified, the visual class that can display the most
7958simultaneous colors on the default screen is chosen.</p>
7959
7960
7961<div style="margin: auto;">
7962  <h3><a class="anchor" id="watermark"></a>-watermark <var>brightness</var>x<var>saturation</var></h3>
7963</div>
7964
7965<p class="magick-description">Watermark an image using the given percentages of brightness and saturation.</p>
7966
7967<p>Take a grayscale image (with alpha mask) and modify the destination image's
7968brightness according to watermark image's grayscale value and the
7969<var>brightness</var> percentage.  The destinations color saturation
7970attribute is just direct modified by the <var>saturation</var>
7971percentage, which defaults to 100 percent (no color change). </p>
7972
7973
7974<div style="margin: auto;">
7975  <h3><a class="anchor" id="wave"></a>-wave <var>amplitude</var><br />-wave <var>amplitude</var>x<var>wavelength</var></h3>
7976</div>
7977
7978<p class="magick-description">Shear the columns of an image into a sine wave.</p>
7979
7980<div style="margin: auto;">
7981  <h3><a class="anchor" id="wavelet-denoise"></a>-wavelet-denoise <var>threshold</var><br />-wavelet-denoise <var>threshold</var>x<var>softness</var></h3>
7982</div>
7983
7984<p class="magick-description">removes noise from the image using a wavelet transform.  The threshold is the value below which everything is considered noise and ranges from 0.0 (none) to QuantumRange or use percent (e.g. 5%). Softness attenuates the threshold and typically ranges from 0.0 (none) to 1.0.  The higher the value the more noise that remains in the image.</p>
7985
7986<div style="margin: auto;">
7987  <h3><a class="anchor" id="weight"></a>-weight <var>fontWeight</var></h3>
7988</div>
7989
7990<p class="magick-description">Set a font weight for text.</p>
7991
7992<p>This setting suggests a font weight that ImageMagick should try to apply to
7993the currently selected font family. Use a positive integer for
7994<var>fontWeight</var> or select from the following.</p>
7995
7996<dl class="row">
7997<dt class="col-md-4">Thin </dt>
7998<dd class="col-md-8">Same as <var>fontWeight</var> = 100.</dd>
7999<dt class="col-md-4">ExtraLight </dt>
8000<dd class="col-md-8">Same as <var>fontWeight</var> = 200.</dd>
8001<dt class="col-md-4">Light </dt>
8002<dd class="col-md-8">Same as <var>fontWeight</var> = 300.</dd>
8003<dt class="col-md-4">Normal </dt>
8004<dd class="col-md-8">Same as <var>fontWeight</var> = 400.</dd>
8005<dt class="col-md-4">Medium </dt>
8006<dd class="col-md-8">Same as <var>fontWeight</var> = 500.</dd>
8007<dt class="col-md-4">DemiBold </dt>
8008<dd class="col-md-8">Same as <var>fontWeight</var> = 600.</dd>
8009<dt class="col-md-4">Bold </dt>
8010<dd class="col-md-8">Same as <var>fontWeight</var> = 700.</dd>
8011<dt class="col-md-4">ExtraBold </dt>
8012<dd class="col-md-8">Same as <var>fontWeight</var> = 800.</dd>
8013<dt class="col-md-4">Heavy </dt>
8014<dd class="col-md-8">Same as <var>fontWeight</var> = 900.</dd>
8015</dl>
8016<br/>
8017
8018<p>To print a complete list of weight types, use <a href="command-line-options.html#list">-list weight</a>.</p>
8019
8020<p>For other settings that affect fonts, see the options <a
8021href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
8022href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#style">-style</a>. </p>
8023
8024<div style="margin: auto;">
8025  <h3><a class="anchor" id="white-point"></a>-white-point <var>x,y</var></h3>
8026</div>
8027
8028<p class="magick-description">chromaticity white point.</p>
8029
8030<div style="margin: auto;">
8031  <h3><a class="anchor" id="white-threshold"></a>-white-threshold <var>value</var>{<var>%</var>}</h3>
8032</div>
8033
8034<p class="magick-description">Force to white all pixels above the threshold while leaving all pixels at or below the threshold unchanged.</p>
8035
8036<p> The threshold value can be given as a percentage or as an absolute integer
8037value within [0, <var>QuantumRange</var>] corresponding to the
8038desired <a href="command-line-options.html#channel">&#x2011;channel</a> value. See <a href="command-line-options.html#threshold">&#x2011;threshold</a>for more details on thresholds and resulting values.  </p>
8039
8040<div style="margin: auto;">
8041  <h3><a class="anchor" id="window"></a>-window <var>id</var></h3>
8042</div>
8043
8044<p class="magick-description">Make the image the background of a window.", 'animate', 'display'</p>
8045
8046<p><var>id</var> can be a window id or name. Specify <code>root</code>
8047to select X's root window as the target window.</p>
8048
8049<p>By default the image is tiled onto the background of the target window. If
8050<code>backdrop</code> or <a href="command-line-options.html#geometry">-resize</a> are specified, the
8051image is surrounded by the background color. Refer to <code>X RESOURCES</code>
8052for details.</p>
8053
8054<p>The image will not display on the root window if the image has more unique
8055colors than the target window colormap allows. Use <a
8056href="command-line-options.html#colors">-colors</a> to reduce the number of colors.</p>
8057
8058<div style="margin: auto;">
8059  <h3><a class="anchor" id="window-group"></a>-window-group</h3>
8060</div>
8061
8062<p class="magick-description">specify the window group.</p>
8063
8064<div style="margin: auto;">
8065  <h3><a class="anchor" id="write"></a>-write <var>filename</var></h3>
8066</div>
8067
8068<p class="magick-description">write an image sequence.</p>
8069
8070<p>The image sequence preceding the <a href="command-line-options.html#write">-write</a> <var>filename</var> option is written out, and processing continues with the same image in its current state if there are additional options. To restore the image to its original state after writing it, use the <a href="command-line-options.html#write">+write</a> <var>filename</var> option.</p>
8071
8072<p>Use <a href="command-line-options.html#compress">-compress</a> to specify the type of image compression.</p>
8073
8074<div style="margin: auto;">
8075  <h3><a class="anchor" id="write-mask"></a>-write-mask <var>filename</var></h3>
8076</div>
8077
8078<p class="magick-description">Prevent updates to image pixels specified by the mask.</p>
8079
8080<p>This the same as using a mask used for composite masking operations, with
8081grayscale values causing blended updates of the image the mask is attached to.
8082</p>
8083
8084<p>Use <a href="command-line-options.html#write-mask">+write-mask</a> to remove the mask from images.</p>
8085
8086<p>Also see <a href="command-line-options.html#clip-mask">-clip-mask</a> which work in the same way,
8087but with strict boolean masking. </p>
8088</div>
8089</div>
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