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