1 : /*
2 : * jcsample.c
3 : *
4 : * Copyright (C) 1991-1996, Thomas G. Lane.
5 : * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
6 : * This file is part of the Independent JPEG Group's software.
7 : * For conditions of distribution and use, see the accompanying README file.
8 : *
9 : * This file contains downsampling routines.
10 : *
11 : * Downsampling input data is counted in "row groups". A row group
12 : * is defined to be max_v_samp_factor pixel rows of each component,
13 : * from which the downsampler produces v_samp_factor sample rows.
14 : * A single row group is processed in each call to the downsampler module.
15 : *
16 : * The downsampler is responsible for edge-expansion of its output data
17 : * to fill an integral number of DCT blocks horizontally. The source buffer
18 : * may be modified if it is helpful for this purpose (the source buffer is
19 : * allocated wide enough to correspond to the desired output width).
20 : * The caller (the prep controller) is responsible for vertical padding.
21 : *
22 : * The downsampler may request "context rows" by setting need_context_rows
23 : * during startup. In this case, the input arrays will contain at least
24 : * one row group's worth of pixels above and below the passed-in data;
25 : * the caller will create dummy rows at image top and bottom by replicating
26 : * the first or last real pixel row.
27 : *
28 : * An excellent reference for image resampling is
29 : * Digital Image Warping, George Wolberg, 1990.
30 : * Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
31 : *
32 : * The downsampling algorithm used here is a simple average of the source
33 : * pixels covered by the output pixel. The hi-falutin sampling literature
34 : * refers to this as a "box filter". In general the characteristics of a box
35 : * filter are not very good, but for the specific cases we normally use (1:1
36 : * and 2:1 ratios) the box is equivalent to a "triangle filter" which is not
37 : * nearly so bad. If you intend to use other sampling ratios, you'd be well
38 : * advised to improve this code.
39 : *
40 : * A simple input-smoothing capability is provided. This is mainly intended
41 : * for cleaning up color-dithered GIF input files (if you find it inadequate,
42 : * we suggest using an external filtering program such as pnmconvol). When
43 : * enabled, each input pixel P is replaced by a weighted sum of itself and its
44 : * eight neighbors. P's weight is 1-8*SF and each neighbor's weight is SF,
45 : * where SF = (smoothing_factor / 1024).
46 : * Currently, smoothing is only supported for 2h2v sampling factors.
47 : */
48 :
49 : #define JPEG_INTERNALS
50 : #include "jinclude.h"
51 : #include "jpeglib.h"
52 : #include "jsimd.h"
53 :
54 :
55 : /* Pointer to routine to downsample a single component */
56 : typedef JMETHOD(void, downsample1_ptr,
57 : (j_compress_ptr cinfo, jpeg_component_info * compptr,
58 : JSAMPARRAY input_data, JSAMPARRAY output_data));
59 :
60 : /* Private subobject */
61 :
62 : typedef struct {
63 : struct jpeg_downsampler pub; /* public fields */
64 :
65 : /* Downsampling method pointers, one per component */
66 : downsample1_ptr methods[MAX_COMPONENTS];
67 : } my_downsampler;
68 :
69 : typedef my_downsampler * my_downsample_ptr;
70 :
71 :
72 : /*
73 : * Initialize for a downsampling pass.
74 : */
75 :
76 : METHODDEF(void)
77 3 : start_pass_downsample (j_compress_ptr cinfo)
78 : {
79 : /* no work for now */
80 3 : }
81 :
82 :
83 : /*
84 : * Expand a component horizontally from width input_cols to width output_cols,
85 : * by duplicating the rightmost samples.
86 : */
87 :
88 : LOCAL(void)
89 432 : expand_right_edge (JSAMPARRAY image_data, int num_rows,
90 : JDIMENSION input_cols, JDIMENSION output_cols)
91 : {
92 : register JSAMPROW ptr;
93 : register JSAMPLE pixval;
94 : register int count;
95 : int row;
96 432 : int numcols = (int) (output_cols - input_cols);
97 :
98 432 : if (numcols > 0) {
99 0 : for (row = 0; row < num_rows; row++) {
100 0 : ptr = image_data[row] + input_cols;
101 0 : pixval = ptr[-1]; /* don't need GETJSAMPLE() here */
102 0 : for (count = numcols; count > 0; count--)
103 0 : *ptr++ = pixval;
104 : }
105 : }
106 432 : }
107 :
108 :
109 : /*
110 : * Do downsampling for a whole row group (all components).
111 : *
112 : * In this version we simply downsample each component independently.
113 : */
114 :
115 : METHODDEF(void)
116 144 : sep_downsample (j_compress_ptr cinfo,
117 : JSAMPIMAGE input_buf, JDIMENSION in_row_index,
118 : JSAMPIMAGE output_buf, JDIMENSION out_row_group_index)
119 : {
120 144 : my_downsample_ptr downsample = (my_downsample_ptr) cinfo->downsample;
121 : int ci;
122 : jpeg_component_info * compptr;
123 : JSAMPARRAY in_ptr, out_ptr;
124 :
125 720 : for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
126 432 : ci++, compptr++) {
127 432 : in_ptr = input_buf[ci] + in_row_index;
128 432 : out_ptr = output_buf[ci] + (out_row_group_index * compptr->v_samp_factor);
129 432 : (*downsample->methods[ci]) (cinfo, compptr, in_ptr, out_ptr);
130 : }
131 144 : }
132 :
133 :
134 : /*
135 : * Downsample pixel values of a single component.
136 : * One row group is processed per call.
137 : * This version handles arbitrary integral sampling ratios, without smoothing.
138 : * Note that this version is not actually used for customary sampling ratios.
139 : */
140 :
141 : METHODDEF(void)
142 0 : int_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
143 : JSAMPARRAY input_data, JSAMPARRAY output_data)
144 : {
145 : int inrow, outrow, h_expand, v_expand, numpix, numpix2, h, v;
146 : JDIMENSION outcol, outcol_h; /* outcol_h == outcol*h_expand */
147 0 : JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
148 : JSAMPROW inptr, outptr;
149 : INT32 outvalue;
150 :
151 0 : h_expand = cinfo->max_h_samp_factor / compptr->h_samp_factor;
152 0 : v_expand = cinfo->max_v_samp_factor / compptr->v_samp_factor;
153 0 : numpix = h_expand * v_expand;
154 0 : numpix2 = numpix/2;
155 :
156 : /* Expand input data enough to let all the output samples be generated
157 : * by the standard loop. Special-casing padded output would be more
158 : * efficient.
159 : */
160 0 : expand_right_edge(input_data, cinfo->max_v_samp_factor,
161 : cinfo->image_width, output_cols * h_expand);
162 :
163 0 : inrow = 0;
164 0 : for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
165 0 : outptr = output_data[outrow];
166 0 : for (outcol = 0, outcol_h = 0; outcol < output_cols;
167 0 : outcol++, outcol_h += h_expand) {
168 0 : outvalue = 0;
169 0 : for (v = 0; v < v_expand; v++) {
170 0 : inptr = input_data[inrow+v] + outcol_h;
171 0 : for (h = 0; h < h_expand; h++) {
172 0 : outvalue += (INT32) GETJSAMPLE(*inptr++);
173 : }
174 : }
175 0 : *outptr++ = (JSAMPLE) ((outvalue + numpix2) / numpix);
176 : }
177 0 : inrow += v_expand;
178 : }
179 0 : }
180 :
181 :
182 : /*
183 : * Downsample pixel values of a single component.
184 : * This version handles the special case of a full-size component,
185 : * without smoothing.
186 : */
187 :
188 : METHODDEF(void)
189 432 : fullsize_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
190 : JSAMPARRAY input_data, JSAMPARRAY output_data)
191 : {
192 : /* Copy the data */
193 432 : jcopy_sample_rows(input_data, 0, output_data, 0,
194 : cinfo->max_v_samp_factor, cinfo->image_width);
195 : /* Edge-expand */
196 432 : expand_right_edge(output_data, cinfo->max_v_samp_factor,
197 432 : cinfo->image_width, compptr->width_in_blocks * DCTSIZE);
198 432 : }
199 :
200 :
201 : /*
202 : * Downsample pixel values of a single component.
203 : * This version handles the common case of 2:1 horizontal and 1:1 vertical,
204 : * without smoothing.
205 : *
206 : * A note about the "bias" calculations: when rounding fractional values to
207 : * integer, we do not want to always round 0.5 up to the next integer.
208 : * If we did that, we'd introduce a noticeable bias towards larger values.
209 : * Instead, this code is arranged so that 0.5 will be rounded up or down at
210 : * alternate pixel locations (a simple ordered dither pattern).
211 : */
212 :
213 : METHODDEF(void)
214 0 : h2v1_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
215 : JSAMPARRAY input_data, JSAMPARRAY output_data)
216 : {
217 : int outrow;
218 : JDIMENSION outcol;
219 0 : JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
220 : register JSAMPROW inptr, outptr;
221 : register int bias;
222 :
223 : /* Expand input data enough to let all the output samples be generated
224 : * by the standard loop. Special-casing padded output would be more
225 : * efficient.
226 : */
227 0 : expand_right_edge(input_data, cinfo->max_v_samp_factor,
228 : cinfo->image_width, output_cols * 2);
229 :
230 0 : for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
231 0 : outptr = output_data[outrow];
232 0 : inptr = input_data[outrow];
233 0 : bias = 0; /* bias = 0,1,0,1,... for successive samples */
234 0 : for (outcol = 0; outcol < output_cols; outcol++) {
235 0 : *outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr) + GETJSAMPLE(inptr[1])
236 0 : + bias) >> 1);
237 0 : bias ^= 1; /* 0=>1, 1=>0 */
238 0 : inptr += 2;
239 : }
240 : }
241 0 : }
242 :
243 :
244 : /*
245 : * Downsample pixel values of a single component.
246 : * This version handles the standard case of 2:1 horizontal and 2:1 vertical,
247 : * without smoothing.
248 : */
249 :
250 : METHODDEF(void)
251 0 : h2v2_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
252 : JSAMPARRAY input_data, JSAMPARRAY output_data)
253 : {
254 : int inrow, outrow;
255 : JDIMENSION outcol;
256 0 : JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
257 : register JSAMPROW inptr0, inptr1, outptr;
258 : register int bias;
259 :
260 : /* Expand input data enough to let all the output samples be generated
261 : * by the standard loop. Special-casing padded output would be more
262 : * efficient.
263 : */
264 0 : expand_right_edge(input_data, cinfo->max_v_samp_factor,
265 : cinfo->image_width, output_cols * 2);
266 :
267 0 : inrow = 0;
268 0 : for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
269 0 : outptr = output_data[outrow];
270 0 : inptr0 = input_data[inrow];
271 0 : inptr1 = input_data[inrow+1];
272 0 : bias = 1; /* bias = 1,2,1,2,... for successive samples */
273 0 : for (outcol = 0; outcol < output_cols; outcol++) {
274 0 : *outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
275 0 : GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1])
276 0 : + bias) >> 2);
277 0 : bias ^= 3; /* 1=>2, 2=>1 */
278 0 : inptr0 += 2; inptr1 += 2;
279 : }
280 0 : inrow += 2;
281 : }
282 0 : }
283 :
284 :
285 : #ifdef INPUT_SMOOTHING_SUPPORTED
286 :
287 : /*
288 : * Downsample pixel values of a single component.
289 : * This version handles the standard case of 2:1 horizontal and 2:1 vertical,
290 : * with smoothing. One row of context is required.
291 : */
292 :
293 : METHODDEF(void)
294 0 : h2v2_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
295 : JSAMPARRAY input_data, JSAMPARRAY output_data)
296 : {
297 : int inrow, outrow;
298 : JDIMENSION colctr;
299 0 : JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
300 : register JSAMPROW inptr0, inptr1, above_ptr, below_ptr, outptr;
301 : INT32 membersum, neighsum, memberscale, neighscale;
302 :
303 : /* Expand input data enough to let all the output samples be generated
304 : * by the standard loop. Special-casing padded output would be more
305 : * efficient.
306 : */
307 0 : expand_right_edge(input_data - 1, cinfo->max_v_samp_factor + 2,
308 : cinfo->image_width, output_cols * 2);
309 :
310 : /* We don't bother to form the individual "smoothed" input pixel values;
311 : * we can directly compute the output which is the average of the four
312 : * smoothed values. Each of the four member pixels contributes a fraction
313 : * (1-8*SF) to its own smoothed image and a fraction SF to each of the three
314 : * other smoothed pixels, therefore a total fraction (1-5*SF)/4 to the final
315 : * output. The four corner-adjacent neighbor pixels contribute a fraction
316 : * SF to just one smoothed pixel, or SF/4 to the final output; while the
317 : * eight edge-adjacent neighbors contribute SF to each of two smoothed
318 : * pixels, or SF/2 overall. In order to use integer arithmetic, these
319 : * factors are scaled by 2^16 = 65536.
320 : * Also recall that SF = smoothing_factor / 1024.
321 : */
322 :
323 0 : memberscale = 16384 - cinfo->smoothing_factor * 80; /* scaled (1-5*SF)/4 */
324 0 : neighscale = cinfo->smoothing_factor * 16; /* scaled SF/4 */
325 :
326 0 : inrow = 0;
327 0 : for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
328 0 : outptr = output_data[outrow];
329 0 : inptr0 = input_data[inrow];
330 0 : inptr1 = input_data[inrow+1];
331 0 : above_ptr = input_data[inrow-1];
332 0 : below_ptr = input_data[inrow+2];
333 :
334 : /* Special case for first column: pretend column -1 is same as column 0 */
335 0 : membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
336 0 : GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
337 0 : neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
338 0 : GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
339 0 : GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[2]) +
340 0 : GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[2]);
341 0 : neighsum += neighsum;
342 0 : neighsum += GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[2]) +
343 0 : GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[2]);
344 0 : membersum = membersum * memberscale + neighsum * neighscale;
345 0 : *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
346 0 : inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2;
347 :
348 0 : for (colctr = output_cols - 2; colctr > 0; colctr--) {
349 : /* sum of pixels directly mapped to this output element */
350 0 : membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
351 0 : GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
352 : /* sum of edge-neighbor pixels */
353 0 : neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
354 0 : GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
355 0 : GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[2]) +
356 0 : GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[2]);
357 : /* The edge-neighbors count twice as much as corner-neighbors */
358 0 : neighsum += neighsum;
359 : /* Add in the corner-neighbors */
360 0 : neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[2]) +
361 0 : GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[2]);
362 : /* form final output scaled up by 2^16 */
363 0 : membersum = membersum * memberscale + neighsum * neighscale;
364 : /* round, descale and output it */
365 0 : *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
366 0 : inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2;
367 : }
368 :
369 : /* Special case for last column */
370 0 : membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
371 0 : GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
372 0 : neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
373 0 : GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
374 0 : GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[1]) +
375 0 : GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[1]);
376 0 : neighsum += neighsum;
377 0 : neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[1]) +
378 0 : GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[1]);
379 0 : membersum = membersum * memberscale + neighsum * neighscale;
380 0 : *outptr = (JSAMPLE) ((membersum + 32768) >> 16);
381 :
382 0 : inrow += 2;
383 : }
384 0 : }
385 :
386 :
387 : /*
388 : * Downsample pixel values of a single component.
389 : * This version handles the special case of a full-size component,
390 : * with smoothing. One row of context is required.
391 : */
392 :
393 : METHODDEF(void)
394 0 : fullsize_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr,
395 : JSAMPARRAY input_data, JSAMPARRAY output_data)
396 : {
397 : int outrow;
398 : JDIMENSION colctr;
399 0 : JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
400 : register JSAMPROW inptr, above_ptr, below_ptr, outptr;
401 : INT32 membersum, neighsum, memberscale, neighscale;
402 : int colsum, lastcolsum, nextcolsum;
403 :
404 : /* Expand input data enough to let all the output samples be generated
405 : * by the standard loop. Special-casing padded output would be more
406 : * efficient.
407 : */
408 0 : expand_right_edge(input_data - 1, cinfo->max_v_samp_factor + 2,
409 : cinfo->image_width, output_cols);
410 :
411 : /* Each of the eight neighbor pixels contributes a fraction SF to the
412 : * smoothed pixel, while the main pixel contributes (1-8*SF). In order
413 : * to use integer arithmetic, these factors are multiplied by 2^16 = 65536.
414 : * Also recall that SF = smoothing_factor / 1024.
415 : */
416 :
417 0 : memberscale = 65536L - cinfo->smoothing_factor * 512L; /* scaled 1-8*SF */
418 0 : neighscale = cinfo->smoothing_factor * 64; /* scaled SF */
419 :
420 0 : for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
421 0 : outptr = output_data[outrow];
422 0 : inptr = input_data[outrow];
423 0 : above_ptr = input_data[outrow-1];
424 0 : below_ptr = input_data[outrow+1];
425 :
426 : /* Special case for first column */
427 0 : colsum = GETJSAMPLE(*above_ptr++) + GETJSAMPLE(*below_ptr++) +
428 0 : GETJSAMPLE(*inptr);
429 0 : membersum = GETJSAMPLE(*inptr++);
430 0 : nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) +
431 0 : GETJSAMPLE(*inptr);
432 0 : neighsum = colsum + (colsum - membersum) + nextcolsum;
433 0 : membersum = membersum * memberscale + neighsum * neighscale;
434 0 : *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
435 0 : lastcolsum = colsum; colsum = nextcolsum;
436 :
437 0 : for (colctr = output_cols - 2; colctr > 0; colctr--) {
438 0 : membersum = GETJSAMPLE(*inptr++);
439 0 : above_ptr++; below_ptr++;
440 0 : nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) +
441 0 : GETJSAMPLE(*inptr);
442 0 : neighsum = lastcolsum + (colsum - membersum) + nextcolsum;
443 0 : membersum = membersum * memberscale + neighsum * neighscale;
444 0 : *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
445 0 : lastcolsum = colsum; colsum = nextcolsum;
446 : }
447 :
448 : /* Special case for last column */
449 0 : membersum = GETJSAMPLE(*inptr);
450 0 : neighsum = lastcolsum + (colsum - membersum) + colsum;
451 0 : membersum = membersum * memberscale + neighsum * neighscale;
452 0 : *outptr = (JSAMPLE) ((membersum + 32768) >> 16);
453 :
454 : }
455 0 : }
456 :
457 : #endif /* INPUT_SMOOTHING_SUPPORTED */
458 :
459 :
460 : /*
461 : * Module initialization routine for downsampling.
462 : * Note that we must select a routine for each component.
463 : */
464 :
465 : GLOBAL(void)
466 3 : jinit_downsampler (j_compress_ptr cinfo)
467 : {
468 : my_downsample_ptr downsample;
469 : int ci;
470 : jpeg_component_info * compptr;
471 3 : boolean smoothok = TRUE;
472 :
473 3 : downsample = (my_downsample_ptr)
474 3 : (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
475 : SIZEOF(my_downsampler));
476 3 : cinfo->downsample = (struct jpeg_downsampler *) downsample;
477 3 : downsample->pub.start_pass = start_pass_downsample;
478 3 : downsample->pub.downsample = sep_downsample;
479 3 : downsample->pub.need_context_rows = FALSE;
480 :
481 3 : if (cinfo->CCIR601_sampling)
482 0 : ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
483 :
484 : /* Verify we can handle the sampling factors, and set up method pointers */
485 15 : for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
486 9 : ci++, compptr++) {
487 18 : if (compptr->h_samp_factor == cinfo->max_h_samp_factor &&
488 9 : compptr->v_samp_factor == cinfo->max_v_samp_factor) {
489 : #ifdef INPUT_SMOOTHING_SUPPORTED
490 18 : if (cinfo->smoothing_factor) {
491 0 : downsample->methods[ci] = fullsize_smooth_downsample;
492 0 : downsample->pub.need_context_rows = TRUE;
493 : } else
494 : #endif
495 9 : downsample->methods[ci] = fullsize_downsample;
496 0 : } else if (compptr->h_samp_factor * 2 == cinfo->max_h_samp_factor &&
497 0 : compptr->v_samp_factor == cinfo->max_v_samp_factor) {
498 0 : smoothok = FALSE;
499 0 : if (jsimd_can_h2v1_downsample())
500 0 : downsample->methods[ci] = jsimd_h2v1_downsample;
501 : else
502 0 : downsample->methods[ci] = h2v1_downsample;
503 0 : } else if (compptr->h_samp_factor * 2 == cinfo->max_h_samp_factor &&
504 0 : compptr->v_samp_factor * 2 == cinfo->max_v_samp_factor) {
505 : #ifdef INPUT_SMOOTHING_SUPPORTED
506 0 : if (cinfo->smoothing_factor) {
507 0 : downsample->methods[ci] = h2v2_smooth_downsample;
508 0 : downsample->pub.need_context_rows = TRUE;
509 : } else
510 : #endif
511 0 : if (jsimd_can_h2v2_downsample())
512 0 : downsample->methods[ci] = jsimd_h2v2_downsample;
513 : else
514 0 : downsample->methods[ci] = h2v2_downsample;
515 0 : } else if ((cinfo->max_h_samp_factor % compptr->h_samp_factor) == 0 &&
516 0 : (cinfo->max_v_samp_factor % compptr->v_samp_factor) == 0) {
517 0 : smoothok = FALSE;
518 0 : downsample->methods[ci] = int_downsample;
519 : } else
520 0 : ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
521 : }
522 :
523 : #ifdef INPUT_SMOOTHING_SUPPORTED
524 3 : if (cinfo->smoothing_factor && !smoothok)
525 0 : TRACEMS(cinfo, 0, JTRC_SMOOTH_NOTIMPL);
526 : #endif
527 3 : }
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