1 /*
2 * jdcolor.c
3 *
4 * Copyright (C) 1991-1997, Thomas G. Lane.
5 * Modified 2011-2017 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 output colorspace conversion routines.
10 */
11
12 #define JPEG_INTERNALS
13 #include "jinclude.h"
14 #include "jpeglib.h"
15
16
17 #if RANGE_BITS < 2
18 /* Deliberate syntax err */
19 Sorry, this code requires 2 or more range extension bits.
20 #endif
21
22
23 /* Private subobject */
24
25 typedef struct {
26 struct jpeg_color_deconverter pub; /* public fields */
27
28 /* Private state for YCbCr->RGB and BG_YCC->RGB conversion */
29 int * Cr_r_tab; /* => table for Cr to R conversion */
30 int * Cb_b_tab; /* => table for Cb to B conversion */
31 INT32 * Cr_g_tab; /* => table for Cr to G conversion */
32 INT32 * Cb_g_tab; /* => table for Cb to G conversion */
33
34 /* Private state for RGB->Y conversion */
35 INT32 * rgb_y_tab; /* => table for RGB to Y conversion */
36 } my_color_deconverter;
37
38 typedef my_color_deconverter * my_cconvert_ptr;
39
40
41 /*************** YCbCr -> RGB conversion: most common case **************/
42 /*************** BG_YCC -> RGB conversion: less common case **************/
43 /*************** RGB -> Y conversion: less common case **************/
44
45 /*
46 * YCbCr is defined per Recommendation ITU-R BT.601-7 (03/2011),
47 * previously known as Recommendation CCIR 601-1, except that Cb and Cr
48 * are normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
49 * sRGB (standard RGB color space) is defined per IEC 61966-2-1:1999.
50 * sYCC (standard luma-chroma-chroma color space with extended gamut)
51 * is defined per IEC 61966-2-1:1999 Amendment A1:2003 Annex F.
52 * bg-sRGB and bg-sYCC (big gamut standard color spaces)
53 * are defined per IEC 61966-2-1:1999 Amendment A1:2003 Annex G.
54 * Note that the derived conversion coefficients given in some of these
55 * documents are imprecise. The general conversion equations are
56 *
57 * R = Y + K * (1 - Kr) * Cr
58 * G = Y - K * (Kb * (1 - Kb) * Cb + Kr * (1 - Kr) * Cr) / (1 - Kr - Kb)
59 * B = Y + K * (1 - Kb) * Cb
60 *
61 * Y = Kr * R + (1 - Kr - Kb) * G + Kb * B
62 *
63 * With Kr = 0.299 and Kb = 0.114 (derived according to SMPTE RP 177-1993
64 * from the 1953 FCC NTSC primaries and CIE Illuminant C), K = 2 for sYCC,
65 * the conversion equations to be implemented are therefore
66 *
67 * R = Y + 1.402 * Cr
68 * G = Y - 0.344136286 * Cb - 0.714136286 * Cr
69 * B = Y + 1.772 * Cb
70 *
71 * Y = 0.299 * R + 0.587 * G + 0.114 * B
72 *
73 * where Cb and Cr represent the incoming values less CENTERJSAMPLE.
74 * For bg-sYCC, with K = 4, the equations are
75 *
76 * R = Y + 2.804 * Cr
77 * G = Y - 0.688272572 * Cb - 1.428272572 * Cr
78 * B = Y + 3.544 * Cb
79 *
80 * To avoid floating-point arithmetic, we represent the fractional constants
81 * as integers scaled up by 2^16 (about 4 digits precision); we have to divide
82 * the products by 2^16, with appropriate rounding, to get the correct answer.
83 * Notice that Y, being an integral input, does not contribute any fraction
84 * so it need not participate in the rounding.
85 *
86 * For even more speed, we avoid doing any multiplications in the inner loop
87 * by precalculating the constants times Cb and Cr for all possible values.
88 * For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table);
89 * for 9-bit to 12-bit samples it is still acceptable. It's not very
90 * reasonable for 16-bit samples, but if you want lossless storage you
91 * shouldn't be changing colorspace anyway.
92 * The Cr=>R and Cb=>B values can be rounded to integers in advance; the
93 * values for the G calculation are left scaled up, since we must add them
94 * together before rounding.
95 */
96
97 #define SCALEBITS 16 /* speediest right-shift on some machines */
98 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
99 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
100
101 /* We allocate one big table for RGB->Y conversion and divide it up into
102 * three parts, instead of doing three alloc_small requests. This lets us
103 * use a single table base address, which can be held in a register in the
104 * inner loops on many machines (more than can hold all three addresses,
105 * anyway).
106 */
107
108 #define R_Y_OFF 0 /* offset to R => Y section */
109 #define G_Y_OFF (1*(MAXJSAMPLE+1)) /* offset to G => Y section */
110 #define B_Y_OFF (2*(MAXJSAMPLE+1)) /* etc. */
111 #define TABLE_SIZE (3*(MAXJSAMPLE+1))
112
113
114 /*
115 * Initialize tables for YCbCr->RGB and BG_YCC->RGB colorspace conversion.
116 */
117
118 LOCAL(void)
119 build_ycc_rgb_table (j_decompress_ptr cinfo)
120 /* Normal case, sYCC */
121 {
122 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
123 int i;
124 INT32 x;
125 SHIFT_TEMPS
126
127 cconvert->Cr_r_tab = (int *)
128 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
129 (MAXJSAMPLE+1) * SIZEOF(int));
130 cconvert->Cb_b_tab = (int *)
131 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
132 (MAXJSAMPLE+1) * SIZEOF(int));
133 cconvert->Cr_g_tab = (INT32 *)
134 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
135 (MAXJSAMPLE+1) * SIZEOF(INT32));
136 cconvert->Cb_g_tab = (INT32 *)
137 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
138 (MAXJSAMPLE+1) * SIZEOF(INT32));
139
140 for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
141 /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
142 /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
143 /* Cr=>R value is nearest int to 1.402 * x */
144 cconvert->Cr_r_tab[i] = (int)
145 RIGHT_SHIFT(FIX(1.402) * x + ONE_HALF, SCALEBITS);
146 /* Cb=>B value is nearest int to 1.772 * x */
147 cconvert->Cb_b_tab[i] = (int)
148 RIGHT_SHIFT(FIX(1.772) * x + ONE_HALF, SCALEBITS);
149 /* Cr=>G value is scaled-up -0.714136286 * x */
150 cconvert->Cr_g_tab[i] = (- FIX(0.714136286)) * x;
151 /* Cb=>G value is scaled-up -0.344136286 * x */
152 /* We also add in ONE_HALF so that need not do it in inner loop */
153 cconvert->Cb_g_tab[i] = (- FIX(0.344136286)) * x + ONE_HALF;
154 }
155 }
156
157
158 LOCAL(void)
159 build_bg_ycc_rgb_table (j_decompress_ptr cinfo)
160 /* Wide gamut case, bg-sYCC */
161 {
162 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
163 int i;
164 INT32 x;
165 SHIFT_TEMPS
166
167 cconvert->Cr_r_tab = (int *)
168 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
169 (MAXJSAMPLE+1) * SIZEOF(int));
170 cconvert->Cb_b_tab = (int *)
171 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
172 (MAXJSAMPLE+1) * SIZEOF(int));
173 cconvert->Cr_g_tab = (INT32 *)
174 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
175 (MAXJSAMPLE+1) * SIZEOF(INT32));
176 cconvert->Cb_g_tab = (INT32 *)
177 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
178 (MAXJSAMPLE+1) * SIZEOF(INT32));
179
180 for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
181 /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
182 /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
183 /* Cr=>R value is nearest int to 2.804 * x */
184 cconvert->Cr_r_tab[i] = (int)
185 RIGHT_SHIFT(FIX(2.804) * x + ONE_HALF, SCALEBITS);
186 /* Cb=>B value is nearest int to 3.544 * x */
187 cconvert->Cb_b_tab[i] = (int)
188 RIGHT_SHIFT(FIX(3.544) * x + ONE_HALF, SCALEBITS);
189 /* Cr=>G value is scaled-up -1.428272572 * x */
190 cconvert->Cr_g_tab[i] = (- FIX(1.428272572)) * x;
191 /* Cb=>G value is scaled-up -0.688272572 * x */
192 /* We also add in ONE_HALF so that need not do it in inner loop */
193 cconvert->Cb_g_tab[i] = (- FIX(0.688272572)) * x + ONE_HALF;
194 }
195 }
196
197
198 /*
199 * Convert some rows of samples to the output colorspace.
200 *
201 * Note that we change from noninterleaved, one-plane-per-component format
202 * to interleaved-pixel format. The output buffer is therefore three times
203 * as wide as the input buffer.
204 * A starting row offset is provided only for the input buffer. The caller
205 * can easily adjust the passed output_buf value to accommodate any row
206 * offset required on that side.
207 */
208
209 METHODDEF(void)
210 ycc_rgb_convert (j_decompress_ptr cinfo,
211 JSAMPIMAGE input_buf, JDIMENSION input_row,
212 JSAMPARRAY output_buf, int num_rows)
213 {
214 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
215 register int y, cb, cr;
216 register JSAMPROW outptr;
217 register JSAMPROW inptr0, inptr1, inptr2;
218 register JDIMENSION col;
219 JDIMENSION num_cols = cinfo->output_width;
220 /* copy these pointers into registers if possible */
221 register JSAMPLE * range_limit = cinfo->sample_range_limit;
222 register int * Crrtab = cconvert->Cr_r_tab;
223 register int * Cbbtab = cconvert->Cb_b_tab;
224 register INT32 * Crgtab = cconvert->Cr_g_tab;
225 register INT32 * Cbgtab = cconvert->Cb_g_tab;
226 SHIFT_TEMPS
227
228 while (--num_rows >= 0) {
229 inptr0 = input_buf[0][input_row];
230 inptr1 = input_buf[1][input_row];
231 inptr2 = input_buf[2][input_row];
232 input_row++;
233 outptr = *output_buf++;
234 for (col = 0; col < num_cols; col++) {
235 y = GETJSAMPLE(inptr0[col]);
236 cb = GETJSAMPLE(inptr1[col]);
237 cr = GETJSAMPLE(inptr2[col]);
238 /* Range-limiting is essential due to noise introduced by DCT losses,
239 * for extended gamut (sYCC) and wide gamut (bg-sYCC) encodings.
240 */
241 outptr[RGB_RED] = range_limit[y + Crrtab[cr]];
242 outptr[RGB_GREEN] = range_limit[y +
243 ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr],
244 SCALEBITS))];
245 outptr[RGB_BLUE] = range_limit[y + Cbbtab[cb]];
246 outptr += RGB_PIXELSIZE;
247 }
248 }
249 }
250
251
252 /**************** Cases other than YCC -> RGB ****************/
253
254
255 /*
256 * Initialize for RGB->grayscale colorspace conversion.
257 */
258
259 LOCAL(void)
260 build_rgb_y_table (j_decompress_ptr cinfo)
261 {
262 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
263 INT32 * rgb_y_tab;
264 INT32 i;
265
266 /* Allocate and fill in the conversion tables. */
267 cconvert->rgb_y_tab = rgb_y_tab = (INT32 *)
268 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
269 (TABLE_SIZE * SIZEOF(INT32)));
270
271 for (i = 0; i <= MAXJSAMPLE; i++) {
272 rgb_y_tab[i+R_Y_OFF] = FIX(0.299) * i;
273 rgb_y_tab[i+G_Y_OFF] = FIX(0.587) * i;
274 rgb_y_tab[i+B_Y_OFF] = FIX(0.114) * i + ONE_HALF;
275 }
276 }
277
278
279 /*
280 * Convert RGB to grayscale.
281 */
282
283 METHODDEF(void)
284 rgb_gray_convert (j_decompress_ptr cinfo,
285 JSAMPIMAGE input_buf, JDIMENSION input_row,
286 JSAMPARRAY output_buf, int num_rows)
287 {
288 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
289 register INT32 * ctab = cconvert->rgb_y_tab;
290 register int r, g, b;
291 register JSAMPROW outptr;
292 register JSAMPROW inptr0, inptr1, inptr2;
293 register JDIMENSION col;
294 JDIMENSION num_cols = cinfo->output_width;
295
296 while (--num_rows >= 0) {
297 inptr0 = input_buf[0][input_row];
298 inptr1 = input_buf[1][input_row];
299 inptr2 = input_buf[2][input_row];
300 input_row++;
301 outptr = *output_buf++;
302 for (col = 0; col < num_cols; col++) {
303 r = GETJSAMPLE(inptr0[col]);
304 g = GETJSAMPLE(inptr1[col]);
305 b = GETJSAMPLE(inptr2[col]);
306 /* Y */
307 outptr[col] = (JSAMPLE)
308 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
309 >> SCALEBITS);
310 }
311 }
312 }
313
314
315 /*
316 * [R-G,G,B-G] to [R,G,B] conversion with modulo calculation
317 * (inverse color transform).
318 * This can be seen as an adaption of the general YCbCr->RGB
319 * conversion equation with Kr = Kb = 0, while replacing the
320 * normalization by modulo calculation.
321 */
322
323 METHODDEF(void)
324 rgb1_rgb_convert (j_decompress_ptr cinfo,
325 JSAMPIMAGE input_buf, JDIMENSION input_row,
326 JSAMPARRAY output_buf, int num_rows)
327 {
328 register int r, g, b;
329 register JSAMPROW outptr;
330 register JSAMPROW inptr0, inptr1, inptr2;
331 register JDIMENSION col;
332 JDIMENSION num_cols = cinfo->output_width;
333
334 while (--num_rows >= 0) {
335 inptr0 = input_buf[0][input_row];
336 inptr1 = input_buf[1][input_row];
337 inptr2 = input_buf[2][input_row];
338 input_row++;
339 outptr = *output_buf++;
340 for (col = 0; col < num_cols; col++) {
341 r = GETJSAMPLE(inptr0[col]);
342 g = GETJSAMPLE(inptr1[col]);
343 b = GETJSAMPLE(inptr2[col]);
344 /* Assume that MAXJSAMPLE+1 is a power of 2, so that the MOD
345 * (modulo) operator is equivalent to the bitmask operator AND.
346 */
347 outptr[RGB_RED] = (JSAMPLE) ((r + g - CENTERJSAMPLE) & MAXJSAMPLE);
348 outptr[RGB_GREEN] = (JSAMPLE) g;
349 outptr[RGB_BLUE] = (JSAMPLE) ((b + g - CENTERJSAMPLE) & MAXJSAMPLE);
350 outptr += RGB_PIXELSIZE;
351 }
352 }
353 }
354
355
356 /*
357 * [R-G,G,B-G] to grayscale conversion with modulo calculation
358 * (inverse color transform).
359 */
360
361 METHODDEF(void)
362 rgb1_gray_convert (j_decompress_ptr cinfo,
363 JSAMPIMAGE input_buf, JDIMENSION input_row,
364 JSAMPARRAY output_buf, int num_rows)
365 {
366 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
367 register INT32 * ctab = cconvert->rgb_y_tab;
368 register int r, g, b;
369 register JSAMPROW outptr;
370 register JSAMPROW inptr0, inptr1, inptr2;
371 register JDIMENSION col;
372 JDIMENSION num_cols = cinfo->output_width;
373
374 while (--num_rows >= 0) {
375 inptr0 = input_buf[0][input_row];
376 inptr1 = input_buf[1][input_row];
377 inptr2 = input_buf[2][input_row];
378 input_row++;
379 outptr = *output_buf++;
380 for (col = 0; col < num_cols; col++) {
381 r = GETJSAMPLE(inptr0[col]);
382 g = GETJSAMPLE(inptr1[col]);
383 b = GETJSAMPLE(inptr2[col]);
384 /* Assume that MAXJSAMPLE+1 is a power of 2, so that the MOD
385 * (modulo) operator is equivalent to the bitmask operator AND.
386 */
387 r = (r + g - CENTERJSAMPLE) & MAXJSAMPLE;
388 b = (b + g - CENTERJSAMPLE) & MAXJSAMPLE;
389 /* Y */
390 outptr[col] = (JSAMPLE)
391 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
392 >> SCALEBITS);
393 }
394 }
395 }
396
397
398 /*
399 * No colorspace change, but conversion from separate-planes
400 * to interleaved representation.
401 */
402
403 METHODDEF(void)
404 rgb_convert (j_decompress_ptr cinfo,
405 JSAMPIMAGE input_buf, JDIMENSION input_row,
406 JSAMPARRAY output_buf, int num_rows)
407 {
408 register JSAMPROW outptr;
409 register JSAMPROW inptr0, inptr1, inptr2;
410 register JDIMENSION col;
411 JDIMENSION num_cols = cinfo->output_width;
412
413 while (--num_rows >= 0) {
414 inptr0 = input_buf[0][input_row];
415 inptr1 = input_buf[1][input_row];
416 inptr2 = input_buf[2][input_row];
417 input_row++;
418 outptr = *output_buf++;
419 for (col = 0; col < num_cols; col++) {
420 /* We can dispense with GETJSAMPLE() here */
421 outptr[RGB_RED] = inptr0[col];
422 outptr[RGB_GREEN] = inptr1[col];
423 outptr[RGB_BLUE] = inptr2[col];
424 outptr += RGB_PIXELSIZE;
425 }
426 }
427 }
428
429
430 /*
431 * Color conversion for no colorspace change: just copy the data,
432 * converting from separate-planes to interleaved representation.
433 */
434
435 METHODDEF(void)
436 null_convert (j_decompress_ptr cinfo,
437 JSAMPIMAGE input_buf, JDIMENSION input_row,
438 JSAMPARRAY output_buf, int num_rows)
439 {
440 int ci;
441 register int nc = cinfo->num_components;
442 register JSAMPROW outptr;
443 register JSAMPROW inptr;
444 register JDIMENSION col;
445 JDIMENSION num_cols = cinfo->output_width;
446
447 while (--num_rows >= 0) {
448 for (ci = 0; ci < nc; ci++) {
449 inptr = input_buf[ci][input_row];
450 outptr = output_buf[0] + ci;
451 for (col = 0; col < num_cols; col++) {
452 *outptr = *inptr++; /* needn't bother with GETJSAMPLE() here */
453 outptr += nc;
454 }
455 }
456 input_row++;
457 output_buf++;
458 }
459 }
460
461
462 /*
463 * Color conversion for grayscale: just copy the data.
464 * This also works for YCC -> grayscale conversion, in which
465 * we just copy the Y (luminance) component and ignore chrominance.
466 */
467
468 METHODDEF(void)
469 grayscale_convert (j_decompress_ptr cinfo,
470 JSAMPIMAGE input_buf, JDIMENSION input_row,
471 JSAMPARRAY output_buf, int num_rows)
472 {
473 jcopy_sample_rows(input_buf[0], (int) input_row, output_buf, 0,
474 num_rows, cinfo->output_width);
475 }
476
477
478 /*
479 * Convert grayscale to RGB: just duplicate the graylevel three times.
480 * This is provided to support applications that don't want to cope
481 * with grayscale as a separate case.
482 */
483
484 METHODDEF(void)
485 gray_rgb_convert (j_decompress_ptr cinfo,
486 JSAMPIMAGE input_buf, JDIMENSION input_row,
487 JSAMPARRAY output_buf, int num_rows)
488 {
489 register JSAMPROW outptr;
490 register JSAMPROW inptr;
491 register JDIMENSION col;
492 JDIMENSION num_cols = cinfo->output_width;
493
494 while (--num_rows >= 0) {
495 inptr = input_buf[0][input_row++];
496 outptr = *output_buf++;
497 for (col = 0; col < num_cols; col++) {
498 /* We can dispense with GETJSAMPLE() here */
499 outptr[RGB_RED] = outptr[RGB_GREEN] = outptr[RGB_BLUE] = inptr[col];
500 outptr += RGB_PIXELSIZE;
501 }
502 }
503 }
504
505
506 /*
507 * Adobe-style YCCK->CMYK conversion.
508 * We convert YCbCr to R=1-C, G=1-M, and B=1-Y using the same
509 * conversion as above, while passing K (black) unchanged.
510 * We assume build_ycc_rgb_table has been called.
511 */
512
513 METHODDEF(void)
514 ycck_cmyk_convert (j_decompress_ptr cinfo,
515 JSAMPIMAGE input_buf, JDIMENSION input_row,
516 JSAMPARRAY output_buf, int num_rows)
517 {
518 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
519 register int y, cb, cr;
520 register JSAMPROW outptr;
521 register JSAMPROW inptr0, inptr1, inptr2, inptr3;
522 register JDIMENSION col;
523 JDIMENSION num_cols = cinfo->output_width;
524 /* copy these pointers into registers if possible */
525 register JSAMPLE * range_limit = cinfo->sample_range_limit;
526 register int * Crrtab = cconvert->Cr_r_tab;
527 register int * Cbbtab = cconvert->Cb_b_tab;
528 register INT32 * Crgtab = cconvert->Cr_g_tab;
529 register INT32 * Cbgtab = cconvert->Cb_g_tab;
530 SHIFT_TEMPS
531
532 while (--num_rows >= 0) {
533 inptr0 = input_buf[0][input_row];
534 inptr1 = input_buf[1][input_row];
535 inptr2 = input_buf[2][input_row];
536 inptr3 = input_buf[3][input_row];
537 input_row++;
538 outptr = *output_buf++;
539 for (col = 0; col < num_cols; col++) {
540 y = GETJSAMPLE(inptr0[col]);
541 cb = GETJSAMPLE(inptr1[col]);
542 cr = GETJSAMPLE(inptr2[col]);
543 /* Range-limiting is essential due to noise introduced by DCT losses,
544 * and for extended gamut encodings (sYCC).
545 */
546 outptr[0] = range_limit[MAXJSAMPLE - (y + Crrtab[cr])]; /* red */
547 outptr[1] = range_limit[MAXJSAMPLE - (y + /* green */
548 ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr],
549 SCALEBITS)))];
550 outptr[2] = range_limit[MAXJSAMPLE - (y + Cbbtab[cb])]; /* blue */
551 /* K passes through unchanged */
552 outptr[3] = inptr3[col]; /* don't need GETJSAMPLE here */
553 outptr += 4;
554 }
555 }
556 }
557
558
559 /*
560 * Empty method for start_pass.
561 */
562
563 METHODDEF(void)
564 start_pass_dcolor (j_decompress_ptr cinfo)
565 {
566 /* no work needed */
567 }
568
569
570 /*
571 * Module initialization routine for output colorspace conversion.
572 */
573
574 GLOBAL(void)
575 jinit_color_deconverter (j_decompress_ptr cinfo)
576 {
577 my_cconvert_ptr cconvert;
578 int ci;
579
580 cconvert = (my_cconvert_ptr)
581 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
582 SIZEOF(my_color_deconverter));
583 cinfo->cconvert = &cconvert->pub;
584 cconvert->pub.start_pass = start_pass_dcolor;
585
586 /* Make sure num_components agrees with jpeg_color_space */
587 switch (cinfo->jpeg_color_space) {
588 case JCS_GRAYSCALE:
589 if (cinfo->num_components != 1)
590 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
591 break;
592
593 case JCS_RGB:
594 case JCS_YCbCr:
595 case JCS_BG_RGB:
596 case JCS_BG_YCC:
597 if (cinfo->num_components != 3)
598 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
599 break;
600
601 case JCS_CMYK:
602 case JCS_YCCK:
603 if (cinfo->num_components != 4)
604 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
605 break;
606
607 default: /* JCS_UNKNOWN can be anything */
608 if (cinfo->num_components < 1)
609 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
610 break;
611 }
612
613 /* Support color transform only for RGB colorspaces */
614 if (cinfo->color_transform &&
615 cinfo->jpeg_color_space != JCS_RGB &&
616 cinfo->jpeg_color_space != JCS_BG_RGB)
617 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
618
619 /* Set out_color_components and conversion method based on requested space.
620 * Also clear the component_needed flags for any unused components,
621 * so that earlier pipeline stages can avoid useless computation.
622 */
623
624 switch (cinfo->out_color_space) {
625 case JCS_GRAYSCALE:
626 cinfo->out_color_components = 1;
627 switch (cinfo->jpeg_color_space) {
628 case JCS_GRAYSCALE:
629 case JCS_YCbCr:
630 case JCS_BG_YCC:
631 cconvert->pub.color_convert = grayscale_convert;
632 /* For color->grayscale conversion, only the Y (0) component is needed */
633 for (ci = 1; ci < cinfo->num_components; ci++)
634 cinfo->comp_info[ci].component_needed = FALSE;
635 break;
636 case JCS_RGB:
637 switch (cinfo->color_transform) {
638 case JCT_NONE:
639 cconvert->pub.color_convert = rgb_gray_convert;
640 break;
641 case JCT_SUBTRACT_GREEN:
642 cconvert->pub.color_convert = rgb1_gray_convert;
643 break;
644 default:
645 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
646 }
647 build_rgb_y_table(cinfo);
648 break;
649 default:
650 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
651 }
652 break;
653
654 case JCS_RGB:
655 cinfo->out_color_components = RGB_PIXELSIZE;
656 switch (cinfo->jpeg_color_space) {
657 case JCS_GRAYSCALE:
658 cconvert->pub.color_convert = gray_rgb_convert;
659 break;
660 case JCS_YCbCr:
661 cconvert->pub.color_convert = ycc_rgb_convert;
662 build_ycc_rgb_table(cinfo);
663 break;
664 case JCS_BG_YCC:
665 cconvert->pub.color_convert = ycc_rgb_convert;
666 build_bg_ycc_rgb_table(cinfo);
667 break;
668 case JCS_RGB:
669 switch (cinfo->color_transform) {
670 case JCT_NONE:
671 cconvert->pub.color_convert = rgb_convert;
672 break;
673 case JCT_SUBTRACT_GREEN:
674 cconvert->pub.color_convert = rgb1_rgb_convert;
675 break;
676 default:
677 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
678 }
679 break;
680 default:
681 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
682 }
683 break;
684
685 case JCS_BG_RGB:
686 cinfo->out_color_components = RGB_PIXELSIZE;
687 if (cinfo->jpeg_color_space == JCS_BG_RGB) {
688 switch (cinfo->color_transform) {
689 case JCT_NONE:
690 cconvert->pub.color_convert = rgb_convert;
691 break;
692 case JCT_SUBTRACT_GREEN:
693 cconvert->pub.color_convert = rgb1_rgb_convert;
694 break;
695 default:
696 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
697 }
698 } else
699 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
700 break;
701
702 case JCS_CMYK:
703 cinfo->out_color_components = 4;
704 switch (cinfo->jpeg_color_space) {
705 case JCS_YCCK:
706 cconvert->pub.color_convert = ycck_cmyk_convert;
707 build_ycc_rgb_table(cinfo);
708 break;
709 case JCS_CMYK:
710 cconvert->pub.color_convert = null_convert;
711 break;
712 default:
713 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
714 }
715 break;
716
717 default:
718 /* Permit null conversion to same output space */
719 if (cinfo->out_color_space == cinfo->jpeg_color_space) {
720 cinfo->out_color_components = cinfo->num_components;
721 cconvert->pub.color_convert = null_convert;
722 } else /* unsupported non-null conversion */
723 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
724 break;
725 }
726
727 if (cinfo->quantize_colors)
728 cinfo->output_components = 1; /* single colormapped output component */
729 else
730 cinfo->output_components = cinfo->out_color_components;
731 }