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comparison mupdf-source/thirdparty/libjpeg/jccolor.c @ 2:b50eed0cc0ef upstream

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ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:43:07 +0200
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1:1d09e1dec1d9 2:b50eed0cc0ef
1 /*
2 * jccolor.c
3 *
4 * Copyright (C) 1991-1996, Thomas G. Lane.
5 * Modified 2011-2023 by Guido Vollbeding.
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 input colorspace conversion routines.
10 */
11
12 #define JPEG_INTERNALS
13 #include "jinclude.h"
14 #include "jpeglib.h"
15
16
17 /* Private subobject */
18
19 typedef struct {
20 struct jpeg_color_converter pub; /* public fields */
21
22 /* Private state for RGB->YCC conversion */
23 INT32 * rgb_ycc_tab; /* => table for RGB to YCbCr conversion */
24 } my_color_converter;
25
26 typedef my_color_converter * my_cconvert_ptr;
27
28
29 /**************** RGB -> YCbCr conversion: most common case **************/
30
31 /*
32 * YCbCr is defined per Recommendation ITU-R BT.601-7 (03/2011),
33 * previously known as Recommendation CCIR 601-1, except that Cb and Cr
34 * are normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
35 * sRGB (standard RGB color space) is defined per IEC 61966-2-1:1999.
36 * sYCC (standard luma-chroma-chroma color space with extended gamut)
37 * is defined per IEC 61966-2-1:1999 Amendment A1:2003 Annex F.
38 * bg-sRGB and bg-sYCC (big gamut standard color spaces)
39 * are defined per IEC 61966-2-1:1999 Amendment A1:2003 Annex G.
40 * Note that the derived conversion coefficients given in some of these
41 * documents are imprecise. The general conversion equations are
42 * Y = Kr * R + (1 - Kr - Kb) * G + Kb * B
43 * Cb = (B - Y) / (1 - Kb) / K
44 * Cr = (R - Y) / (1 - Kr) / K
45 * With Kr = 0.299 and Kb = 0.114 (derived according to SMPTE RP 177-1993
46 * from the 1953 FCC NTSC primaries and CIE Illuminant C), K = 2 for sYCC,
47 * the conversion equations to be implemented are therefore
48 * Y = 0.299 * R + 0.587 * G + 0.114 * B
49 * Cb = -0.168735892 * R - 0.331264108 * G + 0.5 * B + CENTERJSAMPLE
50 * Cr = 0.5 * R - 0.418687589 * G - 0.081312411 * B + CENTERJSAMPLE
51 * Note: older versions of the IJG code used a zero offset of MAXJSAMPLE/2,
52 * rather than CENTERJSAMPLE, for Cb and Cr. This gave equal positive and
53 * negative swings for Cb/Cr, but meant that grayscale values (Cb=Cr=0)
54 * were not represented exactly. Now we sacrifice exact representation of
55 * maximum red and maximum blue in order to get exact grayscales.
56 *
57 * To avoid floating-point arithmetic, we represent the fractional constants
58 * as integers scaled up by 2^16 (about 4 digits precision); we have to divide
59 * the products by 2^16, with appropriate rounding, to get the correct answer.
60 *
61 * For even more speed, we avoid doing any multiplications in the inner loop
62 * by precalculating the constants times R,G,B for all possible values.
63 * For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table);
64 * for 9-bit to 12-bit samples it is still acceptable. It's not very
65 * reasonable for 16-bit samples, but if you want lossless storage
66 * you shouldn't be changing colorspace anyway.
67 * The CENTERJSAMPLE offsets and the rounding fudge-factor of 0.5 are included
68 * in the tables to save adding them separately in the inner loop.
69 */
70
71 #define SCALEBITS 16 /* speediest right-shift on some machines */
72 #define CBCR_OFFSET ((INT32) CENTERJSAMPLE << SCALEBITS)
73 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
74 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
75
76 /* We allocate one big table and divide it up into eight parts, instead of
77 * doing eight alloc_small requests. This lets us use a single table base
78 * address, which can be held in a register in the inner loops on many
79 * machines (more than can hold all eight addresses, anyway).
80 */
81
82 #define R_Y_OFF 0 /* offset to R => Y section */
83 #define G_Y_OFF (1*(MAXJSAMPLE+1)) /* offset to G => Y section */
84 #define B_Y_OFF (2*(MAXJSAMPLE+1)) /* etc. */
85 #define R_CB_OFF (3*(MAXJSAMPLE+1))
86 #define G_CB_OFF (4*(MAXJSAMPLE+1))
87 #define B_CB_OFF (5*(MAXJSAMPLE+1))
88 #define R_CR_OFF B_CB_OFF /* B=>Cb, R=>Cr are the same */
89 #define G_CR_OFF (6*(MAXJSAMPLE+1))
90 #define B_CR_OFF (7*(MAXJSAMPLE+1))
91 #define TABLE_SIZE (8*(MAXJSAMPLE+1))
92
93
94 /*
95 * Initialize for RGB->YCC colorspace conversion.
96 */
97
98 METHODDEF(void)
99 rgb_ycc_start (j_compress_ptr cinfo)
100 {
101 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
102 INT32 * rgb_ycc_tab;
103 INT32 i;
104
105 /* Allocate and fill in the conversion tables. */
106 cconvert->rgb_ycc_tab = rgb_ycc_tab = (INT32 *)
107 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
108 TABLE_SIZE * SIZEOF(INT32));
109
110 for (i = 0; i <= MAXJSAMPLE; i++) {
111 rgb_ycc_tab[i+R_Y_OFF] = FIX(0.299) * i;
112 rgb_ycc_tab[i+G_Y_OFF] = FIX(0.587) * i;
113 rgb_ycc_tab[i+B_Y_OFF] = FIX(0.114) * i + ONE_HALF;
114 rgb_ycc_tab[i+R_CB_OFF] = (- FIX(0.168735892)) * i;
115 rgb_ycc_tab[i+G_CB_OFF] = (- FIX(0.331264108)) * i;
116 /* We use a rounding fudge-factor of 0.5-epsilon for Cb and Cr.
117 * This ensures that the maximum output will round to MAXJSAMPLE
118 * not MAXJSAMPLE+1, and thus that we don't have to range-limit.
119 */
120 rgb_ycc_tab[i+B_CB_OFF] = (i << (SCALEBITS-1)) + CBCR_OFFSET + ONE_HALF-1;
121 /* B=>Cb and R=>Cr tables are the same
122 rgb_ycc_tab[i+R_CR_OFF] = (i << (SCALEBITS-1)) + CBCR_OFFSET + ONE_HALF-1;
123 */
124 rgb_ycc_tab[i+G_CR_OFF] = (- FIX(0.418687589)) * i;
125 rgb_ycc_tab[i+B_CR_OFF] = (- FIX(0.081312411)) * i;
126 }
127 }
128
129
130 /*
131 * Convert some rows of samples to the JPEG colorspace.
132 *
133 * Note that we change from the application's interleaved-pixel format
134 * to our internal noninterleaved, one-plane-per-component format. The
135 * input buffer is therefore three times as wide as the output buffer.
136 *
137 * A starting row offset is provided only for the output buffer. The
138 * caller can easily adjust the passed input_buf value to accommodate
139 * any row offset required on that side.
140 */
141
142 METHODDEF(void)
143 rgb_ycc_convert (j_compress_ptr cinfo,
144 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
145 JDIMENSION output_row, int num_rows)
146 {
147 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
148 register int r, g, b;
149 register INT32 * ctab = cconvert->rgb_ycc_tab;
150 register JSAMPROW inptr;
151 register JSAMPROW outptr0, outptr1, outptr2;
152 register JDIMENSION col;
153 JDIMENSION num_cols = cinfo->image_width;
154
155 while (--num_rows >= 0) {
156 inptr = *input_buf++;
157 outptr0 = output_buf[0][output_row];
158 outptr1 = output_buf[1][output_row];
159 outptr2 = output_buf[2][output_row];
160 output_row++;
161 for (col = 0; col < num_cols; col++) {
162 r = GETJSAMPLE(inptr[RGB_RED]);
163 g = GETJSAMPLE(inptr[RGB_GREEN]);
164 b = GETJSAMPLE(inptr[RGB_BLUE]);
165 inptr += RGB_PIXELSIZE;
166 /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
167 * must be too; we do not need an explicit range-limiting operation.
168 * Hence the value being shifted is never negative, and we don't
169 * need the general RIGHT_SHIFT macro.
170 */
171 /* Y */
172 outptr0[col] = (JSAMPLE)
173 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
174 >> SCALEBITS);
175 /* Cb */
176 outptr1[col] = (JSAMPLE)
177 ((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
178 >> SCALEBITS);
179 /* Cr */
180 outptr2[col] = (JSAMPLE)
181 ((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
182 >> SCALEBITS);
183 }
184 }
185 }
186
187
188 /**************** Cases other than RGB -> YCbCr **************/
189
190
191 /*
192 * Convert some rows of samples to the JPEG colorspace.
193 * This version handles RGB->grayscale conversion,
194 * which is the same as the RGB->Y portion of RGB->YCbCr.
195 * We assume rgb_ycc_start has been called (we only use the Y tables).
196 */
197
198 METHODDEF(void)
199 rgb_gray_convert (j_compress_ptr cinfo,
200 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
201 JDIMENSION output_row, int num_rows)
202 {
203 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
204 register INT32 y;
205 register INT32 * ctab = cconvert->rgb_ycc_tab;
206 register JSAMPROW inptr;
207 register JSAMPROW outptr;
208 register JDIMENSION col;
209 JDIMENSION num_cols = cinfo->image_width;
210
211 while (--num_rows >= 0) {
212 inptr = *input_buf++;
213 outptr = output_buf[0][output_row++];
214 for (col = 0; col < num_cols; col++) {
215 y = ctab[R_Y_OFF + GETJSAMPLE(inptr[RGB_RED])];
216 y += ctab[G_Y_OFF + GETJSAMPLE(inptr[RGB_GREEN])];
217 y += ctab[B_Y_OFF + GETJSAMPLE(inptr[RGB_BLUE])];
218 inptr += RGB_PIXELSIZE;
219 outptr[col] = (JSAMPLE) (y >> SCALEBITS);
220 }
221 }
222 }
223
224
225 /*
226 * Convert some rows of samples to the JPEG colorspace.
227 * This version handles Adobe-style CMYK->YCCK conversion,
228 * where we convert R=1-C, G=1-M, and B=1-Y to YCbCr using the
229 * same conversion as above, while passing K (black) unchanged.
230 * We assume rgb_ycc_start has been called.
231 */
232
233 METHODDEF(void)
234 cmyk_ycck_convert (j_compress_ptr cinfo,
235 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
236 JDIMENSION output_row, int num_rows)
237 {
238 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
239 register int r, g, b;
240 register INT32 * ctab = cconvert->rgb_ycc_tab;
241 register JSAMPROW inptr;
242 register JSAMPROW outptr0, outptr1, outptr2, outptr3;
243 register JDIMENSION col;
244 JDIMENSION num_cols = cinfo->image_width;
245
246 while (--num_rows >= 0) {
247 inptr = *input_buf++;
248 outptr0 = output_buf[0][output_row];
249 outptr1 = output_buf[1][output_row];
250 outptr2 = output_buf[2][output_row];
251 outptr3 = output_buf[3][output_row];
252 output_row++;
253 for (col = 0; col < num_cols; col++) {
254 r = MAXJSAMPLE - GETJSAMPLE(inptr[0]);
255 g = MAXJSAMPLE - GETJSAMPLE(inptr[1]);
256 b = MAXJSAMPLE - GETJSAMPLE(inptr[2]);
257 /* K passes through as-is */
258 outptr3[col] = inptr[3]; /* don't need GETJSAMPLE here */
259 inptr += 4;
260 /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
261 * must be too; we do not need an explicit range-limiting operation.
262 * Hence the value being shifted is never negative, and we don't
263 * need the general RIGHT_SHIFT macro.
264 */
265 /* Y */
266 outptr0[col] = (JSAMPLE)
267 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
268 >> SCALEBITS);
269 /* Cb */
270 outptr1[col] = (JSAMPLE)
271 ((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
272 >> SCALEBITS);
273 /* Cr */
274 outptr2[col] = (JSAMPLE)
275 ((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
276 >> SCALEBITS);
277 }
278 }
279 }
280
281
282 /*
283 * Convert some rows of samples to the JPEG colorspace.
284 * [R,G,B] to [R-G,G,B-G] conversion with modulo calculation
285 * (forward reversible color transform).
286 * This can be seen as an adaption of the general RGB->YCbCr
287 * conversion equation with Kr = Kb = 0, while replacing the
288 * normalization by modulo calculation.
289 */
290
291 METHODDEF(void)
292 rgb_rgb1_convert (j_compress_ptr cinfo,
293 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
294 JDIMENSION output_row, int num_rows)
295 {
296 register int r, g, b;
297 register JSAMPROW inptr;
298 register JSAMPROW outptr0, outptr1, outptr2;
299 register JDIMENSION col;
300 JDIMENSION num_cols = cinfo->image_width;
301
302 while (--num_rows >= 0) {
303 inptr = *input_buf++;
304 outptr0 = output_buf[0][output_row];
305 outptr1 = output_buf[1][output_row];
306 outptr2 = output_buf[2][output_row];
307 output_row++;
308 for (col = 0; col < num_cols; col++) {
309 r = GETJSAMPLE(inptr[RGB_RED]);
310 g = GETJSAMPLE(inptr[RGB_GREEN]);
311 b = GETJSAMPLE(inptr[RGB_BLUE]);
312 inptr += RGB_PIXELSIZE;
313 /* Assume that MAXJSAMPLE+1 is a power of 2, so that the MOD
314 * (modulo) operator is equivalent to the bitmask operator AND.
315 */
316 outptr0[col] = (JSAMPLE) ((r - g + CENTERJSAMPLE) & MAXJSAMPLE);
317 outptr1[col] = (JSAMPLE) g;
318 outptr2[col] = (JSAMPLE) ((b - g + CENTERJSAMPLE) & MAXJSAMPLE);
319 }
320 }
321 }
322
323
324 /*
325 * Convert some rows of samples to the JPEG colorspace.
326 * This version handles grayscale output with no conversion.
327 * The source can be either plain grayscale or YCC (since Y == gray).
328 */
329
330 METHODDEF(void)
331 grayscale_convert (j_compress_ptr cinfo,
332 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
333 JDIMENSION output_row, int num_rows)
334 {
335 register JSAMPROW inptr;
336 register JSAMPROW outptr;
337 register JDIMENSION count;
338 register int instride = cinfo->input_components;
339 JDIMENSION num_cols = cinfo->image_width;
340
341 while (--num_rows >= 0) {
342 inptr = *input_buf++;
343 outptr = output_buf[0][output_row++];
344 for (count = num_cols; count > 0; count--) {
345 *outptr++ = *inptr; /* don't need GETJSAMPLE() here */
346 inptr += instride;
347 }
348 }
349 }
350
351
352 /*
353 * Convert some rows of samples to the JPEG colorspace.
354 * No colorspace conversion, but change from interleaved
355 * to separate-planes representation.
356 */
357
358 METHODDEF(void)
359 rgb_convert (j_compress_ptr cinfo,
360 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
361 JDIMENSION output_row, int num_rows)
362 {
363 register JSAMPROW inptr;
364 register JSAMPROW outptr0, outptr1, outptr2;
365 register JDIMENSION col;
366 JDIMENSION num_cols = cinfo->image_width;
367
368 while (--num_rows >= 0) {
369 inptr = *input_buf++;
370 outptr0 = output_buf[0][output_row];
371 outptr1 = output_buf[1][output_row];
372 outptr2 = output_buf[2][output_row];
373 output_row++;
374 for (col = 0; col < num_cols; col++) {
375 /* We can dispense with GETJSAMPLE() here */
376 outptr0[col] = inptr[RGB_RED];
377 outptr1[col] = inptr[RGB_GREEN];
378 outptr2[col] = inptr[RGB_BLUE];
379 inptr += RGB_PIXELSIZE;
380 }
381 }
382 }
383
384
385 /*
386 * Convert some rows of samples to the JPEG colorspace.
387 * This version handles multi-component colorspaces without conversion.
388 * We assume input_components == num_components.
389 */
390
391 METHODDEF(void)
392 null_convert (j_compress_ptr cinfo,
393 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
394 JDIMENSION output_row, int num_rows)
395 {
396 register JSAMPROW inptr;
397 register JSAMPROW outptr;
398 register JDIMENSION count;
399 register int num_comps = cinfo->num_components;
400 JDIMENSION num_cols = cinfo->image_width;
401 int ci;
402
403 while (--num_rows >= 0) {
404 /* It seems fastest to make a separate pass for each component. */
405 for (ci = 0; ci < num_comps; ci++) {
406 inptr = input_buf[0] + ci;
407 outptr = output_buf[ci][output_row];
408 for (count = num_cols; count > 0; count--) {
409 *outptr++ = *inptr; /* don't need GETJSAMPLE() here */
410 inptr += num_comps;
411 }
412 }
413 input_buf++;
414 output_row++;
415 }
416 }
417
418
419 /*
420 * Empty method for start_pass.
421 */
422
423 METHODDEF(void)
424 null_method (j_compress_ptr cinfo)
425 {
426 /* no work needed */
427 }
428
429
430 /*
431 * Module initialization routine for input colorspace conversion.
432 */
433
434 GLOBAL(void)
435 jinit_color_converter (j_compress_ptr cinfo)
436 {
437 my_cconvert_ptr cconvert;
438
439 cconvert = (my_cconvert_ptr) (*cinfo->mem->alloc_small)
440 ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_color_converter));
441 cinfo->cconvert = &cconvert->pub;
442 /* set start_pass to null method until we find out differently */
443 cconvert->pub.start_pass = null_method;
444
445 /* Make sure input_components agrees with in_color_space */
446 switch (cinfo->in_color_space) {
447 case JCS_GRAYSCALE:
448 if (cinfo->input_components != 1)
449 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
450 break;
451
452 case JCS_RGB:
453 case JCS_BG_RGB:
454 #if RGB_PIXELSIZE != 3
455 if (cinfo->input_components != RGB_PIXELSIZE)
456 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
457 break;
458 #endif /* else share code with YCbCr */
459
460 case JCS_YCbCr:
461 case JCS_BG_YCC:
462 if (cinfo->input_components != 3)
463 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
464 break;
465
466 case JCS_CMYK:
467 case JCS_YCCK:
468 if (cinfo->input_components != 4)
469 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
470 break;
471
472 default: /* JCS_UNKNOWN can be anything */
473 if (cinfo->input_components < 1)
474 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
475 }
476
477 /* Support color transform only for RGB colorspaces */
478 if (cinfo->color_transform &&
479 cinfo->jpeg_color_space != JCS_RGB &&
480 cinfo->jpeg_color_space != JCS_BG_RGB)
481 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
482
483 /* Check num_components, set conversion method based on requested space */
484 switch (cinfo->jpeg_color_space) {
485 case JCS_GRAYSCALE:
486 if (cinfo->num_components != 1)
487 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
488 switch (cinfo->in_color_space) {
489 case JCS_GRAYSCALE:
490 case JCS_YCbCr:
491 case JCS_BG_YCC:
492 cconvert->pub.color_convert = grayscale_convert;
493 break;
494 case JCS_RGB:
495 cconvert->pub.start_pass = rgb_ycc_start;
496 cconvert->pub.color_convert = rgb_gray_convert;
497 break;
498 default:
499 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
500 }
501 break;
502
503 case JCS_RGB:
504 case JCS_BG_RGB:
505 if (cinfo->num_components != 3)
506 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
507 if (cinfo->in_color_space != cinfo->jpeg_color_space)
508 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
509 switch (cinfo->color_transform) {
510 case JCT_NONE:
511 cconvert->pub.color_convert = rgb_convert;
512 break;
513 case JCT_SUBTRACT_GREEN:
514 cconvert->pub.color_convert = rgb_rgb1_convert;
515 break;
516 default:
517 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
518 }
519 break;
520
521 case JCS_YCbCr:
522 if (cinfo->num_components != 3)
523 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
524 switch (cinfo->in_color_space) {
525 case JCS_RGB:
526 cconvert->pub.start_pass = rgb_ycc_start;
527 cconvert->pub.color_convert = rgb_ycc_convert;
528 break;
529 case JCS_YCbCr:
530 cconvert->pub.color_convert = null_convert;
531 break;
532 default:
533 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
534 }
535 break;
536
537 case JCS_BG_YCC:
538 if (cinfo->num_components != 3)
539 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
540 switch (cinfo->in_color_space) {
541 case JCS_RGB:
542 /* For conversion from normal RGB input to BG_YCC representation,
543 * the Cb/Cr values are first computed as usual, and then
544 * quantized further after DCT processing by a factor of
545 * 2 in reference to the nominal quantization factor.
546 */
547 /* need quantization scale by factor of 2 after DCT */
548 cinfo->comp_info[1].component_needed = TRUE;
549 cinfo->comp_info[2].component_needed = TRUE;
550 /* compute normal YCC first */
551 cconvert->pub.start_pass = rgb_ycc_start;
552 cconvert->pub.color_convert = rgb_ycc_convert;
553 break;
554 case JCS_YCbCr:
555 /* need quantization scale by factor of 2 after DCT */
556 cinfo->comp_info[1].component_needed = TRUE;
557 cinfo->comp_info[2].component_needed = TRUE;
558 /*FALLTHROUGH*/
559 case JCS_BG_YCC:
560 /* Pass through for BG_YCC input */
561 cconvert->pub.color_convert = null_convert;
562 break;
563 default:
564 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
565 }
566 break;
567
568 case JCS_CMYK:
569 if (cinfo->num_components != 4)
570 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
571 if (cinfo->in_color_space != JCS_CMYK)
572 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
573 cconvert->pub.color_convert = null_convert;
574 break;
575
576 case JCS_YCCK:
577 if (cinfo->num_components != 4)
578 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
579 switch (cinfo->in_color_space) {
580 case JCS_CMYK:
581 cconvert->pub.start_pass = rgb_ycc_start;
582 cconvert->pub.color_convert = cmyk_ycck_convert;
583 break;
584 case JCS_YCCK:
585 cconvert->pub.color_convert = null_convert;
586 break;
587 default:
588 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
589 }
590 break;
591
592 default: /* allow null conversion of JCS_UNKNOWN */
593 if (cinfo->jpeg_color_space != cinfo->in_color_space ||
594 cinfo->num_components != cinfo->input_components)
595 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
596 cconvert->pub.color_convert = null_convert;
597 }
598 }