mshtml: Implement MediaQueryList's matches prop.
[wine.git] / libs / jpeg / jccolor.c
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1 /*
2 * jccolor.c
4 * Copyright (C) 1991-1996, Thomas G. Lane.
5 * Modified 2011-2019 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.
9 * This file contains input colorspace conversion routines.
12 #define JPEG_INTERNALS
13 #include "jinclude.h"
14 #include "jpeglib.h"
17 /* Private subobject */
19 typedef struct {
20 struct jpeg_color_converter pub; /* public fields */
22 /* Private state for RGB->YCC conversion */
23 INT32 * rgb_ycc_tab; /* => table for RGB to YCbCr conversion */
24 } my_color_converter;
26 typedef my_color_converter * my_cconvert_ptr;
29 /**************** RGB -> YCbCr conversion: most common case **************/
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 = 0.5 * (B - Y) / (1 - Kb)
44 * Cr = 0.5 * (R - Y) / (1 - Kr)
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),
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.
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.
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 you
66 * 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.
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))
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).
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))
95 * Initialize for RGB->YCC colorspace conversion.
98 METHODDEF(void)
99 rgb_ycc_start (j_compress_ptr cinfo)
101 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
102 INT32 * rgb_ycc_tab;
103 INT32 i;
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));
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.
120 rgb_ycc_tab[i+B_CB_OFF] = FIX(0.5) * i + CBCR_OFFSET + ONE_HALF-1;
121 /* B=>Cb and R=>Cr tables are the same
122 rgb_ycc_tab[i+R_CR_OFF] = FIX(0.5) * i + CBCR_OFFSET + ONE_HALF-1;
124 rgb_ycc_tab[i+G_CR_OFF] = (- FIX(0.418687589)) * i;
125 rgb_ycc_tab[i+B_CR_OFF] = (- FIX(0.081312411)) * i;
131 * Convert some rows of samples to the JPEG colorspace.
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.
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.
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)
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;
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.
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);
188 /**************** Cases other than RGB -> YCbCr **************/
192 * Convert some rows of samples to the JPEG colorspace.
193 * This version handles RGB->grayscale conversion, which is the same
194 * as the RGB->Y portion of RGB->YCbCr.
195 * We assume rgb_ycc_start has been called (we only use the Y tables).
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)
203 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
204 register int r, g, b;
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;
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 r = GETJSAMPLE(inptr[RGB_RED]);
216 g = GETJSAMPLE(inptr[RGB_GREEN]);
217 b = GETJSAMPLE(inptr[RGB_BLUE]);
218 inptr += RGB_PIXELSIZE;
219 /* Y */
220 outptr[col] = (JSAMPLE)
221 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
222 >> SCALEBITS);
229 * Convert some rows of samples to the JPEG colorspace.
230 * This version handles Adobe-style CMYK->YCCK conversion,
231 * where we convert R=1-C, G=1-M, and B=1-Y to YCbCr using the
232 * same conversion as above, while passing K (black) unchanged.
233 * We assume rgb_ycc_start has been called.
236 METHODDEF(void)
237 cmyk_ycck_convert (j_compress_ptr cinfo,
238 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
239 JDIMENSION output_row, int num_rows)
241 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
242 register int r, g, b;
243 register INT32 * ctab = cconvert->rgb_ycc_tab;
244 register JSAMPROW inptr;
245 register JSAMPROW outptr0, outptr1, outptr2, outptr3;
246 register JDIMENSION col;
247 JDIMENSION num_cols = cinfo->image_width;
249 while (--num_rows >= 0) {
250 inptr = *input_buf++;
251 outptr0 = output_buf[0][output_row];
252 outptr1 = output_buf[1][output_row];
253 outptr2 = output_buf[2][output_row];
254 outptr3 = output_buf[3][output_row];
255 output_row++;
256 for (col = 0; col < num_cols; col++) {
257 r = MAXJSAMPLE - GETJSAMPLE(inptr[0]);
258 g = MAXJSAMPLE - GETJSAMPLE(inptr[1]);
259 b = MAXJSAMPLE - GETJSAMPLE(inptr[2]);
260 /* K passes through as-is */
261 outptr3[col] = inptr[3]; /* don't need GETJSAMPLE here */
262 inptr += 4;
263 /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
264 * must be too; we do not need an explicit range-limiting operation.
265 * Hence the value being shifted is never negative, and we don't
266 * need the general RIGHT_SHIFT macro.
268 /* Y */
269 outptr0[col] = (JSAMPLE)
270 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
271 >> SCALEBITS);
272 /* Cb */
273 outptr1[col] = (JSAMPLE)
274 ((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
275 >> SCALEBITS);
276 /* Cr */
277 outptr2[col] = (JSAMPLE)
278 ((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
279 >> SCALEBITS);
286 * Convert some rows of samples to the JPEG colorspace.
287 * [R,G,B] to [R-G,G,B-G] conversion with modulo calculation
288 * (forward reversible color transform).
289 * This can be seen as an adaption of the general RGB->YCbCr
290 * conversion equation with Kr = Kb = 0, while replacing the
291 * normalization by modulo calculation.
294 METHODDEF(void)
295 rgb_rgb1_convert (j_compress_ptr cinfo,
296 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
297 JDIMENSION output_row, int num_rows)
299 register int r, g, b;
300 register JSAMPROW inptr;
301 register JSAMPROW outptr0, outptr1, outptr2;
302 register JDIMENSION col;
303 JDIMENSION num_cols = cinfo->image_width;
305 while (--num_rows >= 0) {
306 inptr = *input_buf++;
307 outptr0 = output_buf[0][output_row];
308 outptr1 = output_buf[1][output_row];
309 outptr2 = output_buf[2][output_row];
310 output_row++;
311 for (col = 0; col < num_cols; col++) {
312 r = GETJSAMPLE(inptr[RGB_RED]);
313 g = GETJSAMPLE(inptr[RGB_GREEN]);
314 b = GETJSAMPLE(inptr[RGB_BLUE]);
315 inptr += RGB_PIXELSIZE;
316 /* Assume that MAXJSAMPLE+1 is a power of 2, so that the MOD
317 * (modulo) operator is equivalent to the bitmask operator AND.
319 outptr0[col] = (JSAMPLE) ((r - g + CENTERJSAMPLE) & MAXJSAMPLE);
320 outptr1[col] = (JSAMPLE) g;
321 outptr2[col] = (JSAMPLE) ((b - g + CENTERJSAMPLE) & MAXJSAMPLE);
328 * Convert some rows of samples to the JPEG colorspace.
329 * This version handles grayscale output with no conversion.
330 * The source can be either plain grayscale or YCC (since Y == gray).
333 METHODDEF(void)
334 grayscale_convert (j_compress_ptr cinfo,
335 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
336 JDIMENSION output_row, int num_rows)
338 register JSAMPROW inptr;
339 register JSAMPROW outptr;
340 register JDIMENSION count;
341 register int instride = cinfo->input_components;
342 JDIMENSION num_cols = cinfo->image_width;
344 while (--num_rows >= 0) {
345 inptr = *input_buf++;
346 outptr = output_buf[0][output_row++];
347 for (count = num_cols; count > 0; count--) {
348 *outptr++ = *inptr; /* don't need GETJSAMPLE() here */
349 inptr += instride;
356 * Convert some rows of samples to the JPEG colorspace.
357 * No colorspace conversion, but change from interleaved
358 * to separate-planes representation.
361 METHODDEF(void)
362 rgb_convert (j_compress_ptr cinfo,
363 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
364 JDIMENSION output_row, int num_rows)
366 register JSAMPROW inptr;
367 register JSAMPROW outptr0, outptr1, outptr2;
368 register JDIMENSION col;
369 JDIMENSION num_cols = cinfo->image_width;
371 while (--num_rows >= 0) {
372 inptr = *input_buf++;
373 outptr0 = output_buf[0][output_row];
374 outptr1 = output_buf[1][output_row];
375 outptr2 = output_buf[2][output_row];
376 output_row++;
377 for (col = 0; col < num_cols; col++) {
378 /* We can dispense with GETJSAMPLE() here */
379 outptr0[col] = inptr[RGB_RED];
380 outptr1[col] = inptr[RGB_GREEN];
381 outptr2[col] = inptr[RGB_BLUE];
382 inptr += RGB_PIXELSIZE;
389 * Convert some rows of samples to the JPEG colorspace.
390 * This version handles multi-component colorspaces without conversion.
391 * We assume input_components == num_components.
394 METHODDEF(void)
395 null_convert (j_compress_ptr cinfo,
396 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
397 JDIMENSION output_row, int num_rows)
399 register JSAMPROW inptr;
400 register JSAMPROW outptr;
401 register JDIMENSION count;
402 register int num_comps = cinfo->num_components;
403 JDIMENSION num_cols = cinfo->image_width;
404 int ci;
406 while (--num_rows >= 0) {
407 /* It seems fastest to make a separate pass for each component. */
408 for (ci = 0; ci < num_comps; ci++) {
409 inptr = input_buf[0] + ci;
410 outptr = output_buf[ci][output_row];
411 for (count = num_cols; count > 0; count--) {
412 *outptr++ = *inptr; /* don't need GETJSAMPLE() here */
413 inptr += num_comps;
416 input_buf++;
417 output_row++;
423 * Empty method for start_pass.
426 METHODDEF(void)
427 null_method (j_compress_ptr cinfo)
429 /* no work needed */
434 * Module initialization routine for input colorspace conversion.
437 GLOBAL(void)
438 jinit_color_converter (j_compress_ptr cinfo)
440 my_cconvert_ptr cconvert;
442 cconvert = (my_cconvert_ptr) (*cinfo->mem->alloc_small)
443 ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_color_converter));
444 cinfo->cconvert = &cconvert->pub;
445 /* set start_pass to null method until we find out differently */
446 cconvert->pub.start_pass = null_method;
448 /* Make sure input_components agrees with in_color_space */
449 switch (cinfo->in_color_space) {
450 case JCS_GRAYSCALE:
451 if (cinfo->input_components != 1)
452 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
453 break;
455 case JCS_RGB:
456 case JCS_BG_RGB:
457 #if RGB_PIXELSIZE != 3
458 if (cinfo->input_components != RGB_PIXELSIZE)
459 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
460 break;
461 #endif /* else share code with YCbCr */
463 case JCS_YCbCr:
464 case JCS_BG_YCC:
465 if (cinfo->input_components != 3)
466 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
467 break;
469 case JCS_CMYK:
470 case JCS_YCCK:
471 if (cinfo->input_components != 4)
472 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
473 break;
475 default: /* JCS_UNKNOWN can be anything */
476 if (cinfo->input_components < 1)
477 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
480 /* Support color transform only for RGB colorspaces */
481 if (cinfo->color_transform &&
482 cinfo->jpeg_color_space != JCS_RGB &&
483 cinfo->jpeg_color_space != JCS_BG_RGB)
484 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
486 /* Check num_components, set conversion method based on requested space */
487 switch (cinfo->jpeg_color_space) {
488 case JCS_GRAYSCALE:
489 if (cinfo->num_components != 1)
490 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
491 switch (cinfo->in_color_space) {
492 case JCS_GRAYSCALE:
493 case JCS_YCbCr:
494 case JCS_BG_YCC:
495 cconvert->pub.color_convert = grayscale_convert;
496 break;
497 case JCS_RGB:
498 cconvert->pub.start_pass = rgb_ycc_start;
499 cconvert->pub.color_convert = rgb_gray_convert;
500 break;
501 default:
502 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
504 break;
506 case JCS_RGB:
507 case JCS_BG_RGB:
508 if (cinfo->num_components != 3)
509 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
510 if (cinfo->in_color_space != cinfo->jpeg_color_space)
511 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
512 switch (cinfo->color_transform) {
513 case JCT_NONE:
514 cconvert->pub.color_convert = rgb_convert;
515 break;
516 case JCT_SUBTRACT_GREEN:
517 cconvert->pub.color_convert = rgb_rgb1_convert;
518 break;
519 default:
520 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
522 break;
524 case JCS_YCbCr:
525 if (cinfo->num_components != 3)
526 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
527 switch (cinfo->in_color_space) {
528 case JCS_RGB:
529 cconvert->pub.start_pass = rgb_ycc_start;
530 cconvert->pub.color_convert = rgb_ycc_convert;
531 break;
532 case JCS_YCbCr:
533 cconvert->pub.color_convert = null_convert;
534 break;
535 default:
536 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
538 break;
540 case JCS_BG_YCC:
541 if (cinfo->num_components != 3)
542 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
543 switch (cinfo->in_color_space) {
544 case JCS_RGB:
545 /* For conversion from normal RGB input to BG_YCC representation,
546 * the Cb/Cr values are first computed as usual, and then
547 * quantized further after DCT processing by a factor of
548 * 2 in reference to the nominal quantization factor.
550 /* need quantization scale by factor of 2 after DCT */
551 cinfo->comp_info[1].component_needed = TRUE;
552 cinfo->comp_info[2].component_needed = TRUE;
553 /* compute normal YCC first */
554 cconvert->pub.start_pass = rgb_ycc_start;
555 cconvert->pub.color_convert = rgb_ycc_convert;
556 break;
557 case JCS_YCbCr:
558 /* need quantization scale by factor of 2 after DCT */
559 cinfo->comp_info[1].component_needed = TRUE;
560 cinfo->comp_info[2].component_needed = TRUE;
561 /*FALLTHROUGH*/
562 case JCS_BG_YCC:
563 /* Pass through for BG_YCC input */
564 cconvert->pub.color_convert = null_convert;
565 break;
566 default:
567 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
569 break;
571 case JCS_CMYK:
572 if (cinfo->num_components != 4)
573 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
574 if (cinfo->in_color_space != JCS_CMYK)
575 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
576 cconvert->pub.color_convert = null_convert;
577 break;
579 case JCS_YCCK:
580 if (cinfo->num_components != 4)
581 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
582 switch (cinfo->in_color_space) {
583 case JCS_CMYK:
584 cconvert->pub.start_pass = rgb_ycc_start;
585 cconvert->pub.color_convert = cmyk_ycck_convert;
586 break;
587 case JCS_YCCK:
588 cconvert->pub.color_convert = null_convert;
589 break;
590 default:
591 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
593 break;
595 default: /* allow null conversion of JCS_UNKNOWN */
596 if (cinfo->jpeg_color_space != cinfo->in_color_space ||
597 cinfo->num_components != cinfo->input_components)
598 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
599 cconvert->pub.color_convert = null_convert;