Line data Source code
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 : * Copyright (C) 2015, D. R. Commander.
10 : * For conditions of distribution and use, see the accompanying README.ijg
11 : * file.
12 : *
13 : * This file contains downsampling routines.
14 : *
15 : * Downsampling input data is counted in "row groups". A row group
16 : * is defined to be max_v_samp_factor pixel rows of each component,
17 : * from which the downsampler produces v_samp_factor sample rows.
18 : * A single row group is processed in each call to the downsampler module.
19 : *
20 : * The downsampler is responsible for edge-expansion of its output data
21 : * to fill an integral number of DCT blocks horizontally. The source buffer
22 : * may be modified if it is helpful for this purpose (the source buffer is
23 : * allocated wide enough to correspond to the desired output width).
24 : * The caller (the prep controller) is responsible for vertical padding.
25 : *
26 : * The downsampler may request "context rows" by setting need_context_rows
27 : * during startup. In this case, the input arrays will contain at least
28 : * one row group's worth of pixels above and below the passed-in data;
29 : * the caller will create dummy rows at image top and bottom by replicating
30 : * the first or last real pixel row.
31 : *
32 : * An excellent reference for image resampling is
33 : * Digital Image Warping, George Wolberg, 1990.
34 : * Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
35 : *
36 : * The downsampling algorithm used here is a simple average of the source
37 : * pixels covered by the output pixel. The hi-falutin sampling literature
38 : * refers to this as a "box filter". In general the characteristics of a box
39 : * filter are not very good, but for the specific cases we normally use (1:1
40 : * and 2:1 ratios) the box is equivalent to a "triangle filter" which is not
41 : * nearly so bad. If you intend to use other sampling ratios, you'd be well
42 : * advised to improve this code.
43 : *
44 : * A simple input-smoothing capability is provided. This is mainly intended
45 : * for cleaning up color-dithered GIF input files (if you find it inadequate,
46 : * we suggest using an external filtering program such as pnmconvol). When
47 : * enabled, each input pixel P is replaced by a weighted sum of itself and its
48 : * eight neighbors. P's weight is 1-8*SF and each neighbor's weight is SF,
49 : * where SF = (smoothing_factor / 1024).
50 : * Currently, smoothing is only supported for 2h2v sampling factors.
51 : */
52 :
53 : #define JPEG_INTERNALS
54 : #include "jinclude.h"
55 : #include "jpeglib.h"
56 : #include "jsimd.h"
57 :
58 :
59 : /* Pointer to routine to downsample a single component */
60 : typedef void (*downsample1_ptr) (j_compress_ptr cinfo,
61 : jpeg_component_info *compptr,
62 : JSAMPARRAY input_data,
63 : JSAMPARRAY output_data);
64 :
65 : /* Private subobject */
66 :
67 : typedef struct {
68 : struct jpeg_downsampler pub; /* public fields */
69 :
70 : /* Downsampling method pointers, one per component */
71 : downsample1_ptr methods[MAX_COMPONENTS];
72 : } my_downsampler;
73 :
74 : typedef my_downsampler *my_downsample_ptr;
75 :
76 :
77 : /*
78 : * Initialize for a downsampling pass.
79 : */
80 :
81 : METHODDEF(void)
82 0 : start_pass_downsample (j_compress_ptr cinfo)
83 : {
84 : /* no work for now */
85 0 : }
86 :
87 :
88 : /*
89 : * Expand a component horizontally from width input_cols to width output_cols,
90 : * by duplicating the rightmost samples.
91 : */
92 :
93 : LOCAL(void)
94 0 : expand_right_edge (JSAMPARRAY image_data, int num_rows,
95 : JDIMENSION input_cols, JDIMENSION output_cols)
96 : {
97 : register JSAMPROW ptr;
98 : register JSAMPLE pixval;
99 : register int count;
100 : int row;
101 0 : int numcols = (int) (output_cols - input_cols);
102 :
103 0 : if (numcols > 0) {
104 0 : for (row = 0; row < num_rows; row++) {
105 0 : ptr = image_data[row] + input_cols;
106 0 : pixval = ptr[-1]; /* don't need GETJSAMPLE() here */
107 0 : for (count = numcols; count > 0; count--)
108 0 : *ptr++ = pixval;
109 : }
110 : }
111 0 : }
112 :
113 :
114 : /*
115 : * Do downsampling for a whole row group (all components).
116 : *
117 : * In this version we simply downsample each component independently.
118 : */
119 :
120 : METHODDEF(void)
121 0 : sep_downsample (j_compress_ptr cinfo,
122 : JSAMPIMAGE input_buf, JDIMENSION in_row_index,
123 : JSAMPIMAGE output_buf, JDIMENSION out_row_group_index)
124 : {
125 0 : my_downsample_ptr downsample = (my_downsample_ptr) cinfo->downsample;
126 : int ci;
127 : jpeg_component_info *compptr;
128 : JSAMPARRAY in_ptr, out_ptr;
129 :
130 0 : for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
131 0 : ci++, compptr++) {
132 0 : in_ptr = input_buf[ci] + in_row_index;
133 0 : out_ptr = output_buf[ci] + (out_row_group_index * compptr->v_samp_factor);
134 0 : (*downsample->methods[ci]) (cinfo, compptr, in_ptr, out_ptr);
135 : }
136 0 : }
137 :
138 :
139 : /*
140 : * Downsample pixel values of a single component.
141 : * One row group is processed per call.
142 : * This version handles arbitrary integral sampling ratios, without smoothing.
143 : * Note that this version is not actually used for customary sampling ratios.
144 : */
145 :
146 : METHODDEF(void)
147 0 : int_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr,
148 : JSAMPARRAY input_data, JSAMPARRAY output_data)
149 : {
150 : int inrow, outrow, h_expand, v_expand, numpix, numpix2, h, v;
151 : JDIMENSION outcol, outcol_h; /* outcol_h == outcol*h_expand */
152 0 : JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
153 : JSAMPROW inptr, outptr;
154 : JLONG outvalue;
155 :
156 0 : h_expand = cinfo->max_h_samp_factor / compptr->h_samp_factor;
157 0 : v_expand = cinfo->max_v_samp_factor / compptr->v_samp_factor;
158 0 : numpix = h_expand * v_expand;
159 0 : numpix2 = numpix/2;
160 :
161 : /* Expand input data enough to let all the output samples be generated
162 : * by the standard loop. Special-casing padded output would be more
163 : * efficient.
164 : */
165 0 : expand_right_edge(input_data, cinfo->max_v_samp_factor,
166 : cinfo->image_width, output_cols * h_expand);
167 :
168 0 : inrow = 0;
169 0 : for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
170 0 : outptr = output_data[outrow];
171 0 : for (outcol = 0, outcol_h = 0; outcol < output_cols;
172 0 : outcol++, outcol_h += h_expand) {
173 0 : outvalue = 0;
174 0 : for (v = 0; v < v_expand; v++) {
175 0 : inptr = input_data[inrow+v] + outcol_h;
176 0 : for (h = 0; h < h_expand; h++) {
177 0 : outvalue += (JLONG) GETJSAMPLE(*inptr++);
178 : }
179 : }
180 0 : *outptr++ = (JSAMPLE) ((outvalue + numpix2) / numpix);
181 : }
182 0 : inrow += v_expand;
183 : }
184 0 : }
185 :
186 :
187 : /*
188 : * Downsample pixel values of a single component.
189 : * This version handles the special case of a full-size component,
190 : * without smoothing.
191 : */
192 :
193 : METHODDEF(void)
194 0 : fullsize_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr,
195 : JSAMPARRAY input_data, JSAMPARRAY output_data)
196 : {
197 : /* Copy the data */
198 0 : jcopy_sample_rows(input_data, 0, output_data, 0,
199 : cinfo->max_v_samp_factor, cinfo->image_width);
200 : /* Edge-expand */
201 0 : expand_right_edge(output_data, cinfo->max_v_samp_factor,
202 0 : cinfo->image_width, compptr->width_in_blocks * DCTSIZE);
203 0 : }
204 :
205 :
206 : /*
207 : * Downsample pixel values of a single component.
208 : * This version handles the common case of 2:1 horizontal and 1:1 vertical,
209 : * without smoothing.
210 : *
211 : * A note about the "bias" calculations: when rounding fractional values to
212 : * integer, we do not want to always round 0.5 up to the next integer.
213 : * If we did that, we'd introduce a noticeable bias towards larger values.
214 : * Instead, this code is arranged so that 0.5 will be rounded up or down at
215 : * alternate pixel locations (a simple ordered dither pattern).
216 : */
217 :
218 : METHODDEF(void)
219 0 : h2v1_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr,
220 : JSAMPARRAY input_data, JSAMPARRAY output_data)
221 : {
222 : int outrow;
223 : JDIMENSION outcol;
224 0 : JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
225 : register JSAMPROW inptr, outptr;
226 : register int bias;
227 :
228 : /* Expand input data enough to let all the output samples be generated
229 : * by the standard loop. Special-casing padded output would be more
230 : * efficient.
231 : */
232 0 : expand_right_edge(input_data, cinfo->max_v_samp_factor,
233 : cinfo->image_width, output_cols * 2);
234 :
235 0 : for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
236 0 : outptr = output_data[outrow];
237 0 : inptr = input_data[outrow];
238 0 : bias = 0; /* bias = 0,1,0,1,... for successive samples */
239 0 : for (outcol = 0; outcol < output_cols; outcol++) {
240 0 : *outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr) + GETJSAMPLE(inptr[1])
241 0 : + bias) >> 1);
242 0 : bias ^= 1; /* 0=>1, 1=>0 */
243 0 : inptr += 2;
244 : }
245 : }
246 0 : }
247 :
248 :
249 : /*
250 : * Downsample pixel values of a single component.
251 : * This version handles the standard case of 2:1 horizontal and 2:1 vertical,
252 : * without smoothing.
253 : */
254 :
255 : METHODDEF(void)
256 0 : h2v2_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr,
257 : JSAMPARRAY input_data, JSAMPARRAY output_data)
258 : {
259 : int inrow, outrow;
260 : JDIMENSION outcol;
261 0 : JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
262 : register JSAMPROW inptr0, inptr1, outptr;
263 : register int bias;
264 :
265 : /* Expand input data enough to let all the output samples be generated
266 : * by the standard loop. Special-casing padded output would be more
267 : * efficient.
268 : */
269 0 : expand_right_edge(input_data, cinfo->max_v_samp_factor,
270 : cinfo->image_width, output_cols * 2);
271 :
272 0 : inrow = 0;
273 0 : for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
274 0 : outptr = output_data[outrow];
275 0 : inptr0 = input_data[inrow];
276 0 : inptr1 = input_data[inrow+1];
277 0 : bias = 1; /* bias = 1,2,1,2,... for successive samples */
278 0 : for (outcol = 0; outcol < output_cols; outcol++) {
279 0 : *outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
280 0 : GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1])
281 0 : + bias) >> 2);
282 0 : bias ^= 3; /* 1=>2, 2=>1 */
283 0 : inptr0 += 2; inptr1 += 2;
284 : }
285 0 : inrow += 2;
286 : }
287 0 : }
288 :
289 :
290 : #ifdef INPUT_SMOOTHING_SUPPORTED
291 :
292 : /*
293 : * Downsample pixel values of a single component.
294 : * This version handles the standard case of 2:1 horizontal and 2:1 vertical,
295 : * with smoothing. One row of context is required.
296 : */
297 :
298 : METHODDEF(void)
299 0 : h2v2_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr,
300 : JSAMPARRAY input_data, JSAMPARRAY output_data)
301 : {
302 : int inrow, outrow;
303 : JDIMENSION colctr;
304 0 : JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
305 : register JSAMPROW inptr0, inptr1, above_ptr, below_ptr, outptr;
306 : JLONG membersum, neighsum, memberscale, neighscale;
307 :
308 : /* Expand input data enough to let all the output samples be generated
309 : * by the standard loop. Special-casing padded output would be more
310 : * efficient.
311 : */
312 0 : expand_right_edge(input_data - 1, cinfo->max_v_samp_factor + 2,
313 : cinfo->image_width, output_cols * 2);
314 :
315 : /* We don't bother to form the individual "smoothed" input pixel values;
316 : * we can directly compute the output which is the average of the four
317 : * smoothed values. Each of the four member pixels contributes a fraction
318 : * (1-8*SF) to its own smoothed image and a fraction SF to each of the three
319 : * other smoothed pixels, therefore a total fraction (1-5*SF)/4 to the final
320 : * output. The four corner-adjacent neighbor pixels contribute a fraction
321 : * SF to just one smoothed pixel, or SF/4 to the final output; while the
322 : * eight edge-adjacent neighbors contribute SF to each of two smoothed
323 : * pixels, or SF/2 overall. In order to use integer arithmetic, these
324 : * factors are scaled by 2^16 = 65536.
325 : * Also recall that SF = smoothing_factor / 1024.
326 : */
327 :
328 0 : memberscale = 16384 - cinfo->smoothing_factor * 80; /* scaled (1-5*SF)/4 */
329 0 : neighscale = cinfo->smoothing_factor * 16; /* scaled SF/4 */
330 :
331 0 : inrow = 0;
332 0 : for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
333 0 : outptr = output_data[outrow];
334 0 : inptr0 = input_data[inrow];
335 0 : inptr1 = input_data[inrow+1];
336 0 : above_ptr = input_data[inrow-1];
337 0 : below_ptr = input_data[inrow+2];
338 :
339 : /* Special case for first column: pretend column -1 is same as column 0 */
340 0 : membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
341 0 : GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
342 0 : neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
343 0 : GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
344 0 : GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[2]) +
345 0 : GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[2]);
346 0 : neighsum += neighsum;
347 0 : neighsum += GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[2]) +
348 0 : GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[2]);
349 0 : membersum = membersum * memberscale + neighsum * neighscale;
350 0 : *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
351 0 : inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2;
352 :
353 0 : for (colctr = output_cols - 2; colctr > 0; colctr--) {
354 : /* sum of pixels directly mapped to this output element */
355 0 : membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
356 0 : GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
357 : /* sum of edge-neighbor pixels */
358 0 : neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
359 0 : GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
360 0 : GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[2]) +
361 0 : GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[2]);
362 : /* The edge-neighbors count twice as much as corner-neighbors */
363 0 : neighsum += neighsum;
364 : /* Add in the corner-neighbors */
365 0 : neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[2]) +
366 0 : GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[2]);
367 : /* form final output scaled up by 2^16 */
368 0 : membersum = membersum * memberscale + neighsum * neighscale;
369 : /* round, descale and output it */
370 0 : *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
371 0 : inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2;
372 : }
373 :
374 : /* Special case for last column */
375 0 : membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
376 0 : GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
377 0 : neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
378 0 : GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
379 0 : GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[1]) +
380 0 : GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[1]);
381 0 : neighsum += neighsum;
382 0 : neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[1]) +
383 0 : GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[1]);
384 0 : membersum = membersum * memberscale + neighsum * neighscale;
385 0 : *outptr = (JSAMPLE) ((membersum + 32768) >> 16);
386 :
387 0 : inrow += 2;
388 : }
389 0 : }
390 :
391 :
392 : /*
393 : * Downsample pixel values of a single component.
394 : * This version handles the special case of a full-size component,
395 : * with smoothing. One row of context is required.
396 : */
397 :
398 : METHODDEF(void)
399 0 : fullsize_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr,
400 : JSAMPARRAY input_data, JSAMPARRAY output_data)
401 : {
402 : int outrow;
403 : JDIMENSION colctr;
404 0 : JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE;
405 : register JSAMPROW inptr, above_ptr, below_ptr, outptr;
406 : JLONG membersum, neighsum, memberscale, neighscale;
407 : int colsum, lastcolsum, nextcolsum;
408 :
409 : /* Expand input data enough to let all the output samples be generated
410 : * by the standard loop. Special-casing padded output would be more
411 : * efficient.
412 : */
413 0 : expand_right_edge(input_data - 1, cinfo->max_v_samp_factor + 2,
414 : cinfo->image_width, output_cols);
415 :
416 : /* Each of the eight neighbor pixels contributes a fraction SF to the
417 : * smoothed pixel, while the main pixel contributes (1-8*SF). In order
418 : * to use integer arithmetic, these factors are multiplied by 2^16 = 65536.
419 : * Also recall that SF = smoothing_factor / 1024.
420 : */
421 :
422 0 : memberscale = 65536L - cinfo->smoothing_factor * 512L; /* scaled 1-8*SF */
423 0 : neighscale = cinfo->smoothing_factor * 64; /* scaled SF */
424 :
425 0 : for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) {
426 0 : outptr = output_data[outrow];
427 0 : inptr = input_data[outrow];
428 0 : above_ptr = input_data[outrow-1];
429 0 : below_ptr = input_data[outrow+1];
430 :
431 : /* Special case for first column */
432 0 : colsum = GETJSAMPLE(*above_ptr++) + GETJSAMPLE(*below_ptr++) +
433 0 : GETJSAMPLE(*inptr);
434 0 : membersum = GETJSAMPLE(*inptr++);
435 0 : nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) +
436 0 : GETJSAMPLE(*inptr);
437 0 : neighsum = colsum + (colsum - membersum) + nextcolsum;
438 0 : membersum = membersum * memberscale + neighsum * neighscale;
439 0 : *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
440 0 : lastcolsum = colsum; colsum = nextcolsum;
441 :
442 0 : for (colctr = output_cols - 2; colctr > 0; colctr--) {
443 0 : membersum = GETJSAMPLE(*inptr++);
444 0 : above_ptr++; below_ptr++;
445 0 : nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) +
446 0 : GETJSAMPLE(*inptr);
447 0 : neighsum = lastcolsum + (colsum - membersum) + nextcolsum;
448 0 : membersum = membersum * memberscale + neighsum * neighscale;
449 0 : *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
450 0 : lastcolsum = colsum; colsum = nextcolsum;
451 : }
452 :
453 : /* Special case for last column */
454 0 : membersum = GETJSAMPLE(*inptr);
455 0 : neighsum = lastcolsum + (colsum - membersum) + colsum;
456 0 : membersum = membersum * memberscale + neighsum * neighscale;
457 0 : *outptr = (JSAMPLE) ((membersum + 32768) >> 16);
458 :
459 : }
460 0 : }
461 :
462 : #endif /* INPUT_SMOOTHING_SUPPORTED */
463 :
464 :
465 : /*
466 : * Module initialization routine for downsampling.
467 : * Note that we must select a routine for each component.
468 : */
469 :
470 : GLOBAL(void)
471 0 : jinit_downsampler (j_compress_ptr cinfo)
472 : {
473 : my_downsample_ptr downsample;
474 : int ci;
475 : jpeg_component_info *compptr;
476 0 : boolean smoothok = TRUE;
477 :
478 0 : downsample = (my_downsample_ptr)
479 0 : (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
480 : sizeof(my_downsampler));
481 0 : cinfo->downsample = (struct jpeg_downsampler *) downsample;
482 0 : downsample->pub.start_pass = start_pass_downsample;
483 0 : downsample->pub.downsample = sep_downsample;
484 0 : downsample->pub.need_context_rows = FALSE;
485 :
486 0 : if (cinfo->CCIR601_sampling)
487 0 : ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
488 :
489 : /* Verify we can handle the sampling factors, and set up method pointers */
490 0 : for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
491 0 : ci++, compptr++) {
492 0 : if (compptr->h_samp_factor == cinfo->max_h_samp_factor &&
493 0 : compptr->v_samp_factor == cinfo->max_v_samp_factor) {
494 : #ifdef INPUT_SMOOTHING_SUPPORTED
495 0 : if (cinfo->smoothing_factor) {
496 0 : downsample->methods[ci] = fullsize_smooth_downsample;
497 0 : downsample->pub.need_context_rows = TRUE;
498 : } else
499 : #endif
500 0 : downsample->methods[ci] = fullsize_downsample;
501 0 : } else if (compptr->h_samp_factor * 2 == cinfo->max_h_samp_factor &&
502 0 : compptr->v_samp_factor == cinfo->max_v_samp_factor) {
503 0 : smoothok = FALSE;
504 0 : if (jsimd_can_h2v1_downsample())
505 0 : downsample->methods[ci] = jsimd_h2v1_downsample;
506 : else
507 0 : downsample->methods[ci] = h2v1_downsample;
508 0 : } else if (compptr->h_samp_factor * 2 == cinfo->max_h_samp_factor &&
509 0 : compptr->v_samp_factor * 2 == cinfo->max_v_samp_factor) {
510 : #ifdef INPUT_SMOOTHING_SUPPORTED
511 0 : if (cinfo->smoothing_factor) {
512 : #if defined(__mips__)
513 : if (jsimd_can_h2v2_smooth_downsample())
514 : downsample->methods[ci] = jsimd_h2v2_smooth_downsample;
515 : else
516 : #endif
517 0 : downsample->methods[ci] = h2v2_smooth_downsample;
518 0 : downsample->pub.need_context_rows = TRUE;
519 : } else
520 : #endif
521 : {
522 0 : if (jsimd_can_h2v2_downsample())
523 0 : downsample->methods[ci] = jsimd_h2v2_downsample;
524 : else
525 0 : downsample->methods[ci] = h2v2_downsample;
526 : }
527 0 : } else if ((cinfo->max_h_samp_factor % compptr->h_samp_factor) == 0 &&
528 0 : (cinfo->max_v_samp_factor % compptr->v_samp_factor) == 0) {
529 0 : smoothok = FALSE;
530 0 : downsample->methods[ci] = int_downsample;
531 : } else
532 0 : ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
533 : }
534 :
535 : #ifdef INPUT_SMOOTHING_SUPPORTED
536 0 : if (cinfo->smoothing_factor && !smoothok)
537 0 : TRACEMS(cinfo, 0, JTRC_SMOOTH_NOTIMPL);
538 : #endif
539 0 : }
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