1 2 3<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 4 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 5<html xmlns="http://www.w3.org/1999/xhtml"> 6 <head> 7 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 8 9 <title>Image - Boost.GIL documentation</title> 10 <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> 11 <link rel="stylesheet" href="../_static/style.css" type="text/css" /> 12 <script type="text/javascript"> 13 var DOCUMENTATION_OPTIONS = { 14 URL_ROOT: '../', 15 VERSION: '', 16 COLLAPSE_MODINDEX: false, 17 FILE_SUFFIX: '.html' 18 }; 19 </script> 20 <script type="text/javascript" src="../_static/jquery.js"></script> 21 <script type="text/javascript" src="../_static/underscore.js"></script> 22 <script type="text/javascript" src="../_static/doctools.js"></script> 23 <link rel="index" title="Index" href="../genindex.html" /> 24 <link rel="search" title="Search" href="../search.html" /> 25 <link rel="top" title="Boost.GIL documentation" href="../index.html" /> 26 <link rel="up" title="Design Guide" href="index.html" /> 27 <link rel="next" title="Dynamic images and image views" href="dynamic_image.html" /> 28 <link rel="prev" title="Image View" href="image_view.html" /> 29 </head> 30 <body> 31 <div class="header"> 32 <table border="0" cellpadding="7" cellspacing="0" width="100%" summary= 33 "header"> 34 <tr> 35 <td valign="top" width="300"> 36 <h3><a href="../index.html"><img 37 alt="C++ Boost" src="../_static/gil.png" border="0"></a></h3> 38 </td> 39 40 <td > 41 <h1 align="center"><a href="../index.html"></a></h1> 42 </td> 43 <td> 44 <div id="searchbox" style="display: none"> 45 <form class="search" action="../search.html" method="get"> 46 <input type="text" name="q" size="18" /> 47 <input type="submit" value="Search" /> 48 <input type="hidden" name="check_keywords" value="yes" /> 49 <input type="hidden" name="area" value="default" /> 50 </form> 51 </div> 52 <script type="text/javascript">$('#searchbox').show(0);</script> 53 </td> 54 </tr> 55 </table> 56 </div> 57 <hr/> 58 <div class="content"> 59 <div class="navbar" style="text-align:right;"> 60 61 62 <a class="prev" title="Image View" href="image_view.html"><img src="../_static/prev.png" alt="prev"/></a> 63 <a class="up" title="Design Guide" href="index.html"><img src="../_static/up.png" alt="up"/></a> 64 <a class="next" title="Dynamic images and image views" href="dynamic_image.html"><img src="../_static/next.png" alt="next"/></a> 65 66 </div> 67 68 <div class="section" id="image"> 69<h1>Image</h1> 70<div class="contents local topic" id="contents"> 71<ul class="simple"> 72<li><a class="reference internal" href="#overview" id="id1">Overview</a></li> 73<li><a class="reference internal" href="#models" id="id2">Models</a></li> 74</ul> 75</div> 76<div class="section" id="overview"> 77<h2><a class="toc-backref" href="#id1">Overview</a></h2> 78<p>An image is a container that owns the pixels of a given image view 79It allocates them in its constructor and deletes them in the destructor. 80It has a deep assignment operator and copy constructor. Images are used 81rarely, just when data ownership is important. Most STL algorithms operate on 82ranges, not containers. Similarly most GIL algorithms operate on image views 83(which images provide).</p> 84<p>In the most general form images are N-dimensional and satisfy the following 85concept:</p> 86<div class="highlight-cpp"><div class="highlight"><pre><span class="n">concept</span> <span class="n">RandomAccessNDImageConcept</span><span class="o"><</span><span class="k">typename</span> <span class="n">Img</span><span class="o">></span> <span class="o">:</span> <span class="n">Regular</span><span class="o"><</span><span class="n">Img</span><span class="o">></span> 87<span class="p">{</span> 88 <span class="k">typename</span> <span class="n">view_t</span><span class="p">;</span> <span class="n">where</span> <span class="n">MutableRandomAccessNDImageViewConcept</span><span class="o"><</span><span class="n">view_t</span><span class="o">></span><span class="p">;</span> 89 <span class="k">typename</span> <span class="n">const_view_t</span> <span class="o">=</span> <span class="n">view_t</span><span class="o">::</span><span class="n">const_t</span><span class="p">;</span> 90 <span class="k">typename</span> <span class="n">point_t</span> <span class="o">=</span> <span class="n">view_t</span><span class="o">::</span><span class="n">point_t</span><span class="p">;</span> 91 <span class="k">typename</span> <span class="n">value_type</span> <span class="o">=</span> <span class="n">view_t</span><span class="o">::</span><span class="n">value_type</span><span class="p">;</span> 92 <span class="k">typename</span> <span class="n">allocator_type</span><span class="p">;</span> 93 94 <span class="n">Img</span><span class="o">::</span><span class="n">Img</span><span class="p">(</span><span class="n">point_t</span> <span class="n">dims</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="kt">size_t</span> <span class="n">alignment</span><span class="o">=</span><span class="mi">0</span><span class="p">);</span> 95 <span class="n">Img</span><span class="o">::</span><span class="n">Img</span><span class="p">(</span><span class="n">point_t</span> <span class="n">dims</span><span class="p">,</span> <span class="n">value_type</span> <span class="n">fill_value</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="kt">size_t</span> <span class="n">alignment</span><span class="p">);</span> 96 97 <span class="kt">void</span> <span class="n">Img</span><span class="o">::</span><span class="n">recreate</span><span class="p">(</span><span class="n">point_t</span> <span class="n">new_dims</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="kt">size_t</span> <span class="n">alignment</span><span class="o">=</span><span class="mi">0</span><span class="p">);</span> 98 <span class="kt">void</span> <span class="n">Img</span><span class="o">::</span><span class="n">recreate</span><span class="p">(</span><span class="n">point_t</span> <span class="n">new_dims</span><span class="p">,</span> <span class="n">value_type</span> <span class="n">fill_value</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="kt">size_t</span> <span class="n">alignment</span><span class="p">);</span> 99 100 <span class="k">const</span> <span class="n">point_t</span><span class="o">&</span> <span class="n">Img</span><span class="o">::</span><span class="n">dimensions</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span> 101 <span class="k">const</span> <span class="n">const_view_t</span><span class="o">&</span> <span class="n">const_view</span><span class="p">(</span><span class="k">const</span> <span class="n">Img</span><span class="o">&</span><span class="p">);</span> 102 <span class="k">const</span> <span class="n">view_t</span><span class="o">&</span> <span class="n">view</span><span class="p">(</span><span class="n">Img</span><span class="o">&</span><span class="p">);</span> 103<span class="p">};</span> 104</pre></div> 105</div> 106<p>Two-dimensional images have additional requirements:</p> 107<div class="highlight-cpp"><div class="highlight"><pre><span class="n">concept</span> <span class="n">RandomAccess2DImageConcept</span><span class="o"><</span><span class="n">RandomAccessNDImageConcept</span> <span class="n">Img</span><span class="o">></span> 108<span class="p">{</span> 109 <span class="k">typename</span> <span class="n">x_coord_t</span> <span class="o">=</span> <span class="n">const_view_t</span><span class="o">::</span><span class="n">x_coord_t</span><span class="p">;</span> 110 <span class="k">typename</span> <span class="n">y_coord_t</span> <span class="o">=</span> <span class="n">const_view_t</span><span class="o">::</span><span class="n">y_coord_t</span><span class="p">;</span> 111 112 <span class="n">Img</span><span class="o">::</span><span class="n">Img</span><span class="p">(</span><span class="n">x_coord_t</span> <span class="n">width</span><span class="p">,</span> <span class="n">y_coord_t</span> <span class="n">height</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="kt">size_t</span> <span class="n">alignment</span><span class="o">=</span><span class="mi">0</span><span class="p">);</span> 113 <span class="n">Img</span><span class="o">::</span><span class="n">Img</span><span class="p">(</span><span class="n">x_coord_t</span> <span class="n">width</span><span class="p">,</span> <span class="n">y_coord_t</span> <span class="n">height</span><span class="p">,</span> <span class="n">value_type</span> <span class="n">fill_value</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="kt">size_t</span> <span class="n">alignment</span><span class="p">);</span> 114 115 <span class="n">x_coord_t</span> <span class="n">Img</span><span class="o">::</span><span class="n">width</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span> 116 <span class="n">y_coord_t</span> <span class="n">Img</span><span class="o">::</span><span class="n">height</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span> 117 118 <span class="kt">void</span> <span class="n">Img</span><span class="o">::</span><span class="n">recreate</span><span class="p">(</span><span class="n">x_coord_t</span> <span class="n">width</span><span class="p">,</span> <span class="n">y_coord_t</span> <span class="n">height</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="kt">size_t</span> <span class="n">alignment</span><span class="o">=</span><span class="mi">1</span><span class="p">);</span> 119 <span class="kt">void</span> <span class="n">Img</span><span class="o">::</span><span class="n">recreate</span><span class="p">(</span><span class="n">x_coord_t</span> <span class="n">width</span><span class="p">,</span> <span class="n">y_coord_t</span> <span class="n">height</span><span class="p">,</span> <span class="n">value_type</span> <span class="n">fill_value</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="kt">size_t</span> <span class="n">alignment</span><span class="p">);</span> 120<span class="p">};</span> 121</pre></div> 122</div> 123<p>GIL images have views that model <code class="docutils literal"><span class="pre">ImageViewConcept</span></code> and operate on pixels.</p> 124<div class="highlight-cpp"><div class="highlight"><pre><span class="n">concept</span> <span class="n">ImageConcept</span><span class="o"><</span><span class="n">RandomAccess2DImageConcept</span> <span class="n">Img</span><span class="o">></span> 125<span class="p">{</span> 126 <span class="n">where</span> <span class="n">MutableImageViewConcept</span><span class="o"><</span><span class="n">view_t</span><span class="o">></span><span class="p">;</span> 127 <span class="k">typename</span> <span class="n">coord_t</span> <span class="o">=</span> <span class="n">view_t</span><span class="o">::</span><span class="n">coord_t</span><span class="p">;</span> 128<span class="p">};</span> 129</pre></div> 130</div> 131<p>Images, unlike locators and image views, don’t have ‘mutable’ set of concepts 132because immutable images are not very useful.</p> 133<div class="admonition seealso"> 134<p class="first admonition-title">See also</p> 135<ul class="last simple"> 136<li><a class="reference external" href="reference/structboost_1_1gil_1_1_random_access_n_d_image_concept.html">RandomAccessNDImageConcept<Image></a></li> 137<li><a class="reference external" href="reference/structboost_1_1gil_1_1_random_access2_d_image_concept.html">RandomAccess2DImageConcept<Image></a></li> 138<li><a class="reference external" href="reference/structboost_1_1gil_1_1_image_concept.html">ImageConcept<Image></a></li> 139</ul> 140</div> 141</div> 142<div class="section" id="models"> 143<h2><a class="toc-backref" href="#id2">Models</a></h2> 144<p>GIL provides a class, <code class="docutils literal"><span class="pre">image</span></code>, which is templated over the value type 145(the pixel) and models <code class="docutils literal"><span class="pre">ImageConcept</span></code>:</p> 146<div class="highlight-cpp"><div class="highlight"><pre> <span class="k">template</span> 147 <span class="o"><</span> 148 <span class="k">typename</span> <span class="n">Pixel</span><span class="p">,</span> <span class="c1">// Models PixelValueConcept</span> 149 <span class="kt">bool</span> <span class="n">IsPlanar</span><span class="p">,</span> <span class="c1">// planar or interleaved image</span> 150 <span class="k">typename</span> <span class="n">A</span><span class="o">=</span><span class="n">std</span><span class="o">::</span><span class="n">allocator</span><span class="o"><</span><span class="kt">unsigned</span> <span class="kt">char</span><span class="o">></span> 151 <span class="o">></span> 152<span class="k">class</span> <span class="nc">image</span><span class="p">;</span> 153</pre></div> 154</div> 155<p>The image constructor takes an alignment parameter which allows for 156constructing images that are word-aligned or 8-byte aligned. The alignment is 157specified in bytes. The default value for alignment is 0, which means there is 158no padding at the end of rows. Many operations are faster using such 1591D-traversable images, because <code class="docutils literal"><span class="pre">image_view::x_iterator</span></code> can be used to 160traverse the pixels, instead of the more complicated <code class="docutils literal"><span class="pre">image_view::iterator</span></code>. 161Note that when alignment is 0, packed images are aligned to the bit - i.e. 162there are no padding bits at the end of rows of packed images.</p> 163</div> 164</div> 165 166 167 <div class="navbar" style="text-align:right;"> 168 169 170 <a class="prev" title="Image View" href="image_view.html"><img src="../_static/prev.png" alt="prev"/></a> 171 <a class="up" title="Design Guide" href="index.html"><img src="../_static/up.png" alt="up"/></a> 172 <a class="next" title="Dynamic images and image views" href="dynamic_image.html"><img src="../_static/next.png" alt="next"/></a> 173 174 </div> 175 </div> 176 <div class="footer" role="contentinfo"> 177 Last updated on 2020-08-11 15:08:48. 178 Created using <a href="http://sphinx-doc.org/">Sphinx</a> 1.5.6. 179 </div> 180 </body> 181</html>
