1 /*
2 * jcsample.c
3 *
4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1991-1996, Thomas G. Lane.
6 * libjpeg-turbo Modifications:
7 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
8 * Copyright (C) 2014, MIPS Technologies, Inc., California
9 * For conditions of distribution and use, see the accompanying README file.
10 *
11 * This file contains downsampling routines.
12 *
13 * Downsampling input data is counted in "row groups". A row group
14 * is defined to be max_v_samp_factor pixel rows of each component,
15 * from which the downsampler produces v_samp_factor sample rows.
16 * A single row group is processed in each call to the downsampler module.
17 *
18 * The downsampler is responsible for edge-expansion of its output data
19 * to fill an integral number of DCT blocks horizontally. The source buffer
20 * may be modified if it is helpful for this purpose (the source buffer is
21 * allocated wide enough to correspond to the desired output width).
22 * The caller (the prep controller) is responsible for vertical padding.
23 *
24 * The downsampler may request "context rows" by setting need_context_rows
25 * during startup. In this case, the input arrays will contain at least
26 * one row group's worth of pixels above and below the passed-in data;
27 * the caller will create dummy rows at image top and bottom by replicating
28 * the first or last real pixel row.
29 *
30 * An excellent reference for image resampling is
31 * Digital Image Warping, George Wolberg, 1990.
32 * Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
33 *
34 * The downsampling algorithm used here is a simple average of the source
35 * pixels covered by the output pixel. The hi-falutin sampling literature
36 * refers to this as a "box filter". In general the characteristics of a box
37 * filter are not very good, but for the specific cases we normally use (1:1
38 * and 2:1 ratios) the box is equivalent to a "triangle filter" which is not
39 * nearly so bad. If you intend to use other sampling ratios, you'd be well
40 * advised to improve this code.
41 *
42 * A simple input-smoothing capability is provided. This is mainly intended
43 * for cleaning up color-dithered GIF input files (if you find it inadequate,
44 * we suggest using an external filtering program such as pnmconvol). When
45 * enabled, each input pixel P is replaced by a weighted sum of itself and its
46 * eight neighbors. P's weight is 1-8*SF and each neighbor's weight is SF,
47 * where SF = (smoothing_factor / 1024).
48 * Currently, smoothing is only supported for 2h2v sampling factors.
49 */
50
51 #define JPEG_INTERNALS
52 #include "jinclude.h"
53 #include "jpeglib.h"
54 #include "jsimd.h"
55
56
57 /* Pointer to routine to downsample a single component */
58 typedef void (*downsample1_ptr) (j_compress_ptr cinfo,
59 jpeg_component_info * compptr,
60 JSAMPARRAY input_data,
61 JSAMPARRAY output_data);
62
63 /* Private subobject */
64
65 typedef struct {
66 struct jpeg_downsampler pub; /* public fields */
67
68 /* Downsampling method pointers, one per component */
69 downsample1_ptr methods[MAX_COMPONENTS];
70 } my_downsampler;
71
72 typedef my_downsampler * my_downsample_ptr;
73
74
75 /*
76 * Initialize for a downsampling pass.
77 */
78
79 METHODDEF(void)
start_pass_downsample(j_compress_ptr cinfo)80 start_pass_downsample (j_compress_ptr cinfo)
81 {
82 /* no work for now */
83 }
84
85
86 /*
87 * Expand a component horizontally from width input_cols to width output_cols,
88 * by duplicating the rightmost samples.
89 */
90
91 LOCAL(void)
expand_right_edge(JSAMPARRAY image_data,int num_rows,JDIMENSION input_cols,JDIMENSION output_cols)92 expand_right_edge (JSAMPARRAY image_data, int num_rows,
93 JDIMENSION input_cols, JDIMENSION output_cols)
94 {
95 register JSAMPROW ptr;
96 register JSAMPLE pixval;
97 register int count;
98 int row;
99 int numcols = (int) (output_cols - input_cols);
100
101 if (numcols > 0) {
102 for (row = 0; row < num_rows; row++) {
103 ptr = image_data[row] + input_cols;
104 pixval = ptr[-1]; /* don't need GETJSAMPLE() here */
105 for (count = numcols; count > 0; count--)
106 *ptr++ = pixval;
107 }
108 }
109 }
110
111
112 /*
113 * Do downsampling for a whole row group (all components).
114 *
115 * In this version we simply downsample each component independently.
116 */
117
118 METHODDEF(void)
sep_downsample(j_compress_ptr cinfo,JSAMPIMAGE input_buf,JDIMENSION in_row_index,JSAMPIMAGE output_buf,JDIMENSION out_row_group_index)119 sep_downsample (j_compress_ptr cinfo,
120 JSAMPIMAGE input_buf, JDIMENSION in_row_index,
121 JSAMPIMAGE output_buf, JDIMENSION out_row_group_index)
122 {
123 my_downsample_ptr downsample = (my_downsample_ptr) cinfo->downsample;
124 int ci;
125 jpeg_component_info * compptr;
126 JSAMPARRAY in_ptr, out_ptr;
127
128 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
129 ci++, compptr++) {
130 in_ptr = input_buf[ci] + in_row_index;
131 out_ptr = output_buf[ci] + (out_row_group_index * compptr->v_samp_factor);
132 (*downsample->methods[ci]) (cinfo, compptr, in_ptr, out_ptr);
133 }
134 }
135
136
137 /*
138 * Downsample pixel values of a single component.
139 * One row group is processed per call.
140 * This version handles arbitrary integral sampling ratios, without smoothing.
141 * Note that this version is not actually used for customary sampling ratios.
142 */
143
144 METHODDEF(void)
int_downsample(j_compress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY input_data,JSAMPARRAY output_data)145 int_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
146 JSAMPARRAY input_data, JSAMPARRAY output_data)
147 {
148 int inrow, outrow, h_expand, v_expand, numpix, numpix2, h, v;
149 JDIMENSION outcol, outcol_h; /* outcol_h == outcol*h_expand */
150 JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
151 JSAMPROW inptr, outptr;
152 INT32 outvalue;
153
154 h_expand = cinfo->max_h_samp_factor / compptr->h_samp_factor;
155 v_expand = cinfo->max_v_samp_factor / compptr->v_samp_factor;
156 numpix = h_expand * v_expand;
157 numpix2 = numpix/2;
158
159 /* Expand input data enough to let all the output samples be generated
160 * by the standard loop. Special-casing padded output would be more
161 * efficient.
162 */
163 expand_right_edge(input_data, cinfo->max_v_samp_factor,
164 cinfo->image_width, output_cols * h_expand);
165
166 inrow = 0;
167 for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
168 outptr = output_data[outrow];
169 for (outcol = 0, outcol_h = 0; outcol < output_cols;
170 outcol++, outcol_h += h_expand) {
171 outvalue = 0;
172 for (v = 0; v < v_expand; v++) {
173 inptr = input_data[inrow+v] + outcol_h;
174 for (h = 0; h < h_expand; h++) {
175 outvalue += (INT32) GETJSAMPLE(*inptr++);
176 }
177 }
178 *outptr++ = (JSAMPLE) ((outvalue + numpix2) / numpix);
179 }
180 inrow += v_expand;
181 }
182 }
183
184
185 /*
186 * Downsample pixel values of a single component.
187 * This version handles the special case of a full-size component,
188 * without smoothing.
189 */
190
191 METHODDEF(void)
fullsize_downsample(j_compress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY input_data,JSAMPARRAY output_data)192 fullsize_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
193 JSAMPARRAY input_data, JSAMPARRAY output_data)
194 {
195 /* Copy the data */
196 jcopy_sample_rows(input_data, 0, output_data, 0,
197 cinfo->max_v_samp_factor, cinfo->image_width);
198 /* Edge-expand */
199 expand_right_edge(output_data, cinfo->max_v_samp_factor,
200 cinfo->image_width, compptr->width_in_blocks * DCTSIZE);
201 }
202
203
204 /*
205 * Downsample pixel values of a single component.
206 * This version handles the common case of 2:1 horizontal and 1:1 vertical,
207 * without smoothing.
208 *
209 * A note about the "bias" calculations: when rounding fractional values to
210 * integer, we do not want to always round 0.5 up to the next integer.
211 * If we did that, we'd introduce a noticeable bias towards larger values.
212 * Instead, this code is arranged so that 0.5 will be rounded up or down at
213 * alternate pixel locations (a simple ordered dither pattern).
214 */
215
216 METHODDEF(void)
h2v1_downsample(j_compress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY input_data,JSAMPARRAY output_data)217 h2v1_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
218 JSAMPARRAY input_data, JSAMPARRAY output_data)
219 {
220 int outrow;
221 JDIMENSION outcol;
222 JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
223 register JSAMPROW inptr, outptr;
224 register int bias;
225
226 /* Expand input data enough to let all the output samples be generated
227 * by the standard loop. Special-casing padded output would be more
228 * efficient.
229 */
230 expand_right_edge(input_data, cinfo->max_v_samp_factor,
231 cinfo->image_width, output_cols * 2);
232
233 for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
234 outptr = output_data[outrow];
235 inptr = input_data[outrow];
236 bias = 0; /* bias = 0,1,0,1,... for successive samples */
237 for (outcol = 0; outcol < output_cols; outcol++) {
238 *outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr) + GETJSAMPLE(inptr[1])
239 + bias) >> 1);
240 bias ^= 1; /* 0=>1, 1=>0 */
241 inptr += 2;
242 }
243 }
244 }
245
246
247 /*
248 * Downsample pixel values of a single component.
249 * This version handles the standard case of 2:1 horizontal and 2:1 vertical,
250 * without smoothing.
251 */
252
253 METHODDEF(void)
h2v2_downsample(j_compress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY input_data,JSAMPARRAY output_data)254 h2v2_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
255 JSAMPARRAY input_data, JSAMPARRAY output_data)
256 {
257 int inrow, outrow;
258 JDIMENSION outcol;
259 JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
260 register JSAMPROW inptr0, inptr1, outptr;
261 register int bias;
262
263 /* Expand input data enough to let all the output samples be generated
264 * by the standard loop. Special-casing padded output would be more
265 * efficient.
266 */
267 expand_right_edge(input_data, cinfo->max_v_samp_factor,
268 cinfo->image_width, output_cols * 2);
269
270 inrow = 0;
271 for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
272 outptr = output_data[outrow];
273 inptr0 = input_data[inrow];
274 inptr1 = input_data[inrow+1];
275 bias = 1; /* bias = 1,2,1,2,... for successive samples */
276 for (outcol = 0; outcol < output_cols; outcol++) {
277 *outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
278 GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1])
279 + bias) >> 2);
280 bias ^= 3; /* 1=>2, 2=>1 */
281 inptr0 += 2; inptr1 += 2;
282 }
283 inrow += 2;
284 }
285 }
286
287
288 #ifdef INPUT_SMOOTHING_SUPPORTED
289
290 /*
291 * Downsample pixel values of a single component.
292 * This version handles the standard case of 2:1 horizontal and 2:1 vertical,
293 * with smoothing. One row of context is required.
294 */
295
296 METHODDEF(void)
h2v2_smooth_downsample(j_compress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY input_data,JSAMPARRAY output_data)297 h2v2_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
298 JSAMPARRAY input_data, JSAMPARRAY output_data)
299 {
300 int inrow, outrow;
301 JDIMENSION colctr;
302 JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
303 register JSAMPROW inptr0, inptr1, above_ptr, below_ptr, outptr;
304 INT32 membersum, neighsum, memberscale, neighscale;
305
306 /* Expand input data enough to let all the output samples be generated
307 * by the standard loop. Special-casing padded output would be more
308 * efficient.
309 */
310 expand_right_edge(input_data - 1, cinfo->max_v_samp_factor + 2,
311 cinfo->image_width, output_cols * 2);
312
313 /* We don't bother to form the individual "smoothed" input pixel values;
314 * we can directly compute the output which is the average of the four
315 * smoothed values. Each of the four member pixels contributes a fraction
316 * (1-8*SF) to its own smoothed image and a fraction SF to each of the three
317 * other smoothed pixels, therefore a total fraction (1-5*SF)/4 to the final
318 * output. The four corner-adjacent neighbor pixels contribute a fraction
319 * SF to just one smoothed pixel, or SF/4 to the final output; while the
320 * eight edge-adjacent neighbors contribute SF to each of two smoothed
321 * pixels, or SF/2 overall. In order to use integer arithmetic, these
322 * factors are scaled by 2^16 = 65536.
323 * Also recall that SF = smoothing_factor / 1024.
324 */
325
326 memberscale = 16384 - cinfo->smoothing_factor * 80; /* scaled (1-5*SF)/4 */
327 neighscale = cinfo->smoothing_factor * 16; /* scaled SF/4 */
328
329 inrow = 0;
330 for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
331 outptr = output_data[outrow];
332 inptr0 = input_data[inrow];
333 inptr1 = input_data[inrow+1];
334 above_ptr = input_data[inrow-1];
335 below_ptr = input_data[inrow+2];
336
337 /* Special case for first column: pretend column -1 is same as column 0 */
338 membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
339 GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
340 neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
341 GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
342 GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[2]) +
343 GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[2]);
344 neighsum += neighsum;
345 neighsum += GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[2]) +
346 GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[2]);
347 membersum = membersum * memberscale + neighsum * neighscale;
348 *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
349 inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2;
350
351 for (colctr = output_cols - 2; colctr > 0; colctr--) {
352 /* sum of pixels directly mapped to this output element */
353 membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
354 GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
355 /* sum of edge-neighbor pixels */
356 neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
357 GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
358 GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[2]) +
359 GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[2]);
360 /* The edge-neighbors count twice as much as corner-neighbors */
361 neighsum += neighsum;
362 /* Add in the corner-neighbors */
363 neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[2]) +
364 GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[2]);
365 /* form final output scaled up by 2^16 */
366 membersum = membersum * memberscale + neighsum * neighscale;
367 /* round, descale and output it */
368 *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
369 inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2;
370 }
371
372 /* Special case for last column */
373 membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
374 GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
375 neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
376 GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
377 GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[1]) +
378 GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[1]);
379 neighsum += neighsum;
380 neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[1]) +
381 GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[1]);
382 membersum = membersum * memberscale + neighsum * neighscale;
383 *outptr = (JSAMPLE) ((membersum + 32768) >> 16);
384
385 inrow += 2;
386 }
387 }
388
389
390 /*
391 * Downsample pixel values of a single component.
392 * This version handles the special case of a full-size component,
393 * with smoothing. One row of context is required.
394 */
395
396 METHODDEF(void)
fullsize_smooth_downsample(j_compress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY input_data,JSAMPARRAY output_data)397 fullsize_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr,
398 JSAMPARRAY input_data, JSAMPARRAY output_data)
399 {
400 int outrow;
401 JDIMENSION colctr;
402 JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
403 register JSAMPROW inptr, above_ptr, below_ptr, outptr;
404 INT32 membersum, neighsum, memberscale, neighscale;
405 int colsum, lastcolsum, nextcolsum;
406
407 /* Expand input data enough to let all the output samples be generated
408 * by the standard loop. Special-casing padded output would be more
409 * efficient.
410 */
411 expand_right_edge(input_data - 1, cinfo->max_v_samp_factor + 2,
412 cinfo->image_width, output_cols);
413
414 /* Each of the eight neighbor pixels contributes a fraction SF to the
415 * smoothed pixel, while the main pixel contributes (1-8*SF). In order
416 * to use integer arithmetic, these factors are multiplied by 2^16 = 65536.
417 * Also recall that SF = smoothing_factor / 1024.
418 */
419
420 memberscale = 65536L - cinfo->smoothing_factor * 512L; /* scaled 1-8*SF */
421 neighscale = cinfo->smoothing_factor * 64; /* scaled SF */
422
423 for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
424 outptr = output_data[outrow];
425 inptr = input_data[outrow];
426 above_ptr = input_data[outrow-1];
427 below_ptr = input_data[outrow+1];
428
429 /* Special case for first column */
430 colsum = GETJSAMPLE(*above_ptr++) + GETJSAMPLE(*below_ptr++) +
431 GETJSAMPLE(*inptr);
432 membersum = GETJSAMPLE(*inptr++);
433 nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) +
434 GETJSAMPLE(*inptr);
435 neighsum = colsum + (colsum - membersum) + nextcolsum;
436 membersum = membersum * memberscale + neighsum * neighscale;
437 *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
438 lastcolsum = colsum; colsum = nextcolsum;
439
440 for (colctr = output_cols - 2; colctr > 0; colctr--) {
441 membersum = GETJSAMPLE(*inptr++);
442 above_ptr++; below_ptr++;
443 nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) +
444 GETJSAMPLE(*inptr);
445 neighsum = lastcolsum + (colsum - membersum) + nextcolsum;
446 membersum = membersum * memberscale + neighsum * neighscale;
447 *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
448 lastcolsum = colsum; colsum = nextcolsum;
449 }
450
451 /* Special case for last column */
452 membersum = GETJSAMPLE(*inptr);
453 neighsum = lastcolsum + (colsum - membersum) + colsum;
454 membersum = membersum * memberscale + neighsum * neighscale;
455 *outptr = (JSAMPLE) ((membersum + 32768) >> 16);
456
457 }
458 }
459
460 #endif /* INPUT_SMOOTHING_SUPPORTED */
461
462
463 /*
464 * Module initialization routine for downsampling.
465 * Note that we must select a routine for each component.
466 */
467
468 GLOBAL(void)
jinit_downsampler(j_compress_ptr cinfo)469 jinit_downsampler (j_compress_ptr cinfo)
470 {
471 my_downsample_ptr downsample;
472 int ci;
473 jpeg_component_info * compptr;
474 boolean smoothok = TRUE;
475
476 downsample = (my_downsample_ptr)
477 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
478 sizeof(my_downsampler));
479 cinfo->downsample = (struct jpeg_downsampler *) downsample;
480 downsample->pub.start_pass = start_pass_downsample;
481 downsample->pub.downsample = sep_downsample;
482 downsample->pub.need_context_rows = FALSE;
483
484 if (cinfo->CCIR601_sampling)
485 ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
486
487 /* Verify we can handle the sampling factors, and set up method pointers */
488 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
489 ci++, compptr++) {
490 if (compptr->h_samp_factor == cinfo->max_h_samp_factor &&
491 compptr->v_samp_factor == cinfo->max_v_samp_factor) {
492 #ifdef INPUT_SMOOTHING_SUPPORTED
493 if (cinfo->smoothing_factor) {
494 downsample->methods[ci] = fullsize_smooth_downsample;
495 downsample->pub.need_context_rows = TRUE;
496 } else
497 #endif
498 downsample->methods[ci] = fullsize_downsample;
499 } else if (compptr->h_samp_factor * 2 == cinfo->max_h_samp_factor &&
500 compptr->v_samp_factor == cinfo->max_v_samp_factor) {
501 smoothok = FALSE;
502 if (jsimd_can_h2v1_downsample())
503 downsample->methods[ci] = jsimd_h2v1_downsample;
504 else
505 downsample->methods[ci] = h2v1_downsample;
506 } else if (compptr->h_samp_factor * 2 == cinfo->max_h_samp_factor &&
507 compptr->v_samp_factor * 2 == cinfo->max_v_samp_factor) {
508 #ifdef INPUT_SMOOTHING_SUPPORTED
509 if (cinfo->smoothing_factor) {
510 #if defined(__mips__)
511 if (jsimd_can_h2v2_smooth_downsample())
512 downsample->methods[ci] = jsimd_h2v2_smooth_downsample;
513 else
514 #endif
515 downsample->methods[ci] = h2v2_smooth_downsample;
516 downsample->pub.need_context_rows = TRUE;
517 } else
518 #endif
519 {
520 if (jsimd_can_h2v2_downsample())
521 downsample->methods[ci] = jsimd_h2v2_downsample;
522 else
523 downsample->methods[ci] = h2v2_downsample;
524 }
525 } else if ((cinfo->max_h_samp_factor % compptr->h_samp_factor) == 0 &&
526 (cinfo->max_v_samp_factor % compptr->v_samp_factor) == 0) {
527 smoothok = FALSE;
528 downsample->methods[ci] = int_downsample;
529 } else
530 ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
531 }
532
533 #ifdef INPUT_SMOOTHING_SUPPORTED
534 if (cinfo->smoothing_factor && !smoothok)
535 TRACEMS(cinfo, 0, JTRC_SMOOTH_NOTIMPL);
536 #endif
537 }
538