1 /*
2 * jccolor.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 input colorspace conversion routines.
9 */
10
11 #define JPEG_INTERNALS
12 #include "jinclude.h"
13 #include "jpeglib.h"
14
15 // this enables unrolling null_convert's loop, and reading/write ints for speed
16 #define ENABLE_ANDROID_NULL_CONVERT
17
18 /* Private subobject */
19
20 typedef struct {
21 struct jpeg_color_converter pub; /* public fields */
22
23 /* Private state for RGB->YCC conversion */
24 INT32 * rgb_ycc_tab; /* => table for RGB to YCbCr conversion */
25 } my_color_converter;
26
27 typedef my_color_converter * my_cconvert_ptr;
28
29
30 /**************** RGB -> YCbCr conversion: most common case **************/
31
32 /*
33 * YCbCr is defined per CCIR 601-1, except that Cb and Cr are
34 * normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
35 * The conversion equations to be implemented are therefore
36 * Y = 0.29900 * R + 0.58700 * G + 0.11400 * B
37 * Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE
38 * Cr = 0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE
39 * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.)
40 * Note: older versions of the IJG code used a zero offset of MAXJSAMPLE/2,
41 * rather than CENTERJSAMPLE, for Cb and Cr. This gave equal positive and
42 * negative swings for Cb/Cr, but meant that grayscale values (Cb=Cr=0)
43 * were not represented exactly. Now we sacrifice exact representation of
44 * maximum red and maximum blue in order to get exact grayscales.
45 *
46 * To avoid floating-point arithmetic, we represent the fractional constants
47 * as integers scaled up by 2^16 (about 4 digits precision); we have to divide
48 * the products by 2^16, with appropriate rounding, to get the correct answer.
49 *
50 * For even more speed, we avoid doing any multiplications in the inner loop
51 * by precalculating the constants times R,G,B for all possible values.
52 * For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table);
53 * for 12-bit samples it is still acceptable. It's not very reasonable for
54 * 16-bit samples, but if you want lossless storage you shouldn't be changing
55 * colorspace anyway.
56 * The CENTERJSAMPLE offsets and the rounding fudge-factor of 0.5 are included
57 * in the tables to save adding them separately in the inner loop.
58 */
59
60 #define SCALEBITS 16 /* speediest right-shift on some machines */
61 #define CBCR_OFFSET ((INT32) CENTERJSAMPLE << SCALEBITS)
62 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
63 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
64
65 /* We allocate one big table and divide it up into eight parts, instead of
66 * doing eight alloc_small requests. This lets us use a single table base
67 * address, which can be held in a register in the inner loops on many
68 * machines (more than can hold all eight addresses, anyway).
69 */
70
71 #define R_Y_OFF 0 /* offset to R => Y section */
72 #define G_Y_OFF (1*(MAXJSAMPLE+1)) /* offset to G => Y section */
73 #define B_Y_OFF (2*(MAXJSAMPLE+1)) /* etc. */
74 #define R_CB_OFF (3*(MAXJSAMPLE+1))
75 #define G_CB_OFF (4*(MAXJSAMPLE+1))
76 #define B_CB_OFF (5*(MAXJSAMPLE+1))
77 #define R_CR_OFF B_CB_OFF /* B=>Cb, R=>Cr are the same */
78 #define G_CR_OFF (6*(MAXJSAMPLE+1))
79 #define B_CR_OFF (7*(MAXJSAMPLE+1))
80 #define TABLE_SIZE (8*(MAXJSAMPLE+1))
81
82
83 /*
84 * Initialize for RGB->YCC colorspace conversion.
85 */
86
87 METHODDEF(void)
rgb_ycc_start(j_compress_ptr cinfo)88 rgb_ycc_start (j_compress_ptr cinfo)
89 {
90 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
91 INT32 * rgb_ycc_tab;
92 INT32 i;
93
94 /* Allocate and fill in the conversion tables. */
95 cconvert->rgb_ycc_tab = rgb_ycc_tab = (INT32 *)
96 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
97 (TABLE_SIZE * SIZEOF(INT32)));
98
99 for (i = 0; i <= MAXJSAMPLE; i++) {
100 rgb_ycc_tab[i+R_Y_OFF] = FIX(0.29900) * i;
101 rgb_ycc_tab[i+G_Y_OFF] = FIX(0.58700) * i;
102 rgb_ycc_tab[i+B_Y_OFF] = FIX(0.11400) * i + ONE_HALF;
103 rgb_ycc_tab[i+R_CB_OFF] = (-FIX(0.16874)) * i;
104 rgb_ycc_tab[i+G_CB_OFF] = (-FIX(0.33126)) * i;
105 /* We use a rounding fudge-factor of 0.5-epsilon for Cb and Cr.
106 * This ensures that the maximum output will round to MAXJSAMPLE
107 * not MAXJSAMPLE+1, and thus that we don't have to range-limit.
108 */
109 rgb_ycc_tab[i+B_CB_OFF] = FIX(0.50000) * i + CBCR_OFFSET + ONE_HALF-1;
110 /* B=>Cb and R=>Cr tables are the same
111 rgb_ycc_tab[i+R_CR_OFF] = FIX(0.50000) * i + CBCR_OFFSET + ONE_HALF-1;
112 */
113 rgb_ycc_tab[i+G_CR_OFF] = (-FIX(0.41869)) * i;
114 rgb_ycc_tab[i+B_CR_OFF] = (-FIX(0.08131)) * i;
115 }
116 }
117
118
119 /*
120 * Convert some rows of samples to the JPEG colorspace.
121 *
122 * Note that we change from the application's interleaved-pixel format
123 * to our internal noninterleaved, one-plane-per-component format.
124 * The input buffer is therefore three times as wide as the output buffer.
125 *
126 * A starting row offset is provided only for the output buffer. The caller
127 * can easily adjust the passed input_buf value to accommodate any row
128 * offset required on that side.
129 */
130
131 METHODDEF(void)
rgb_ycc_convert(j_compress_ptr cinfo,JSAMPARRAY input_buf,JSAMPIMAGE output_buf,JDIMENSION output_row,int num_rows)132 rgb_ycc_convert (j_compress_ptr cinfo,
133 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
134 JDIMENSION output_row, int num_rows)
135 {
136 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
137 register int r, g, b;
138 register INT32 * ctab = cconvert->rgb_ycc_tab;
139 register JSAMPROW inptr;
140 register JSAMPROW outptr0, outptr1, outptr2;
141 register JDIMENSION col;
142 JDIMENSION num_cols = cinfo->image_width;
143
144 while (--num_rows >= 0) {
145 inptr = *input_buf++;
146 outptr0 = output_buf[0][output_row];
147 outptr1 = output_buf[1][output_row];
148 outptr2 = output_buf[2][output_row];
149 output_row++;
150 for (col = 0; col < num_cols; col++) {
151 r = GETJSAMPLE(inptr[RGB_RED]);
152 g = GETJSAMPLE(inptr[RGB_GREEN]);
153 b = GETJSAMPLE(inptr[RGB_BLUE]);
154 inptr += RGB_PIXELSIZE;
155 /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
156 * must be too; we do not need an explicit range-limiting operation.
157 * Hence the value being shifted is never negative, and we don't
158 * need the general RIGHT_SHIFT macro.
159 */
160 /* Y */
161 outptr0[col] = (JSAMPLE)
162 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
163 >> SCALEBITS);
164 /* Cb */
165 outptr1[col] = (JSAMPLE)
166 ((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
167 >> SCALEBITS);
168 /* Cr */
169 outptr2[col] = (JSAMPLE)
170 ((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
171 >> SCALEBITS);
172 }
173 }
174 }
175
176
177 /**************** Cases other than RGB -> YCbCr **************/
178
179
180 /*
181 * Convert some rows of samples to the JPEG colorspace.
182 * This version handles RGB->grayscale conversion, which is the same
183 * as the RGB->Y portion of RGB->YCbCr.
184 * We assume rgb_ycc_start has been called (we only use the Y tables).
185 */
186
187 METHODDEF(void)
rgb_gray_convert(j_compress_ptr cinfo,JSAMPARRAY input_buf,JSAMPIMAGE output_buf,JDIMENSION output_row,int num_rows)188 rgb_gray_convert (j_compress_ptr cinfo,
189 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
190 JDIMENSION output_row, int num_rows)
191 {
192 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
193 register int r, g, b;
194 register INT32 * ctab = cconvert->rgb_ycc_tab;
195 register JSAMPROW inptr;
196 register JSAMPROW outptr;
197 register JDIMENSION col;
198 JDIMENSION num_cols = cinfo->image_width;
199
200 while (--num_rows >= 0) {
201 inptr = *input_buf++;
202 outptr = output_buf[0][output_row];
203 output_row++;
204 for (col = 0; col < num_cols; col++) {
205 r = GETJSAMPLE(inptr[RGB_RED]);
206 g = GETJSAMPLE(inptr[RGB_GREEN]);
207 b = GETJSAMPLE(inptr[RGB_BLUE]);
208 inptr += RGB_PIXELSIZE;
209 /* Y */
210 outptr[col] = (JSAMPLE)
211 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
212 >> SCALEBITS);
213 }
214 }
215 }
216
217
218 /*
219 * Convert some rows of samples to the JPEG colorspace.
220 * This version handles Adobe-style CMYK->YCCK conversion,
221 * where we convert R=1-C, G=1-M, and B=1-Y to YCbCr using the same
222 * conversion as above, while passing K (black) unchanged.
223 * We assume rgb_ycc_start has been called.
224 */
225
226 METHODDEF(void)
cmyk_ycck_convert(j_compress_ptr cinfo,JSAMPARRAY input_buf,JSAMPIMAGE output_buf,JDIMENSION output_row,int num_rows)227 cmyk_ycck_convert (j_compress_ptr cinfo,
228 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
229 JDIMENSION output_row, int num_rows)
230 {
231 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
232 register int r, g, b;
233 register INT32 * ctab = cconvert->rgb_ycc_tab;
234 register JSAMPROW inptr;
235 register JSAMPROW outptr0, outptr1, outptr2, outptr3;
236 register JDIMENSION col;
237 JDIMENSION num_cols = cinfo->image_width;
238
239 while (--num_rows >= 0) {
240 inptr = *input_buf++;
241 outptr0 = output_buf[0][output_row];
242 outptr1 = output_buf[1][output_row];
243 outptr2 = output_buf[2][output_row];
244 outptr3 = output_buf[3][output_row];
245 output_row++;
246 for (col = 0; col < num_cols; col++) {
247 r = MAXJSAMPLE - GETJSAMPLE(inptr[0]);
248 g = MAXJSAMPLE - GETJSAMPLE(inptr[1]);
249 b = MAXJSAMPLE - GETJSAMPLE(inptr[2]);
250 /* K passes through as-is */
251 outptr3[col] = inptr[3]; /* don't need GETJSAMPLE here */
252 inptr += 4;
253 /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
254 * must be too; we do not need an explicit range-limiting operation.
255 * Hence the value being shifted is never negative, and we don't
256 * need the general RIGHT_SHIFT macro.
257 */
258 /* Y */
259 outptr0[col] = (JSAMPLE)
260 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
261 >> SCALEBITS);
262 /* Cb */
263 outptr1[col] = (JSAMPLE)
264 ((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
265 >> SCALEBITS);
266 /* Cr */
267 outptr2[col] = (JSAMPLE)
268 ((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
269 >> SCALEBITS);
270 }
271 }
272 }
273
274
275 /*
276 * Convert some rows of samples to the JPEG colorspace.
277 * This version handles grayscale output with no conversion.
278 * The source can be either plain grayscale or YCbCr (since Y == gray).
279 */
280
281 METHODDEF(void)
grayscale_convert(j_compress_ptr cinfo,JSAMPARRAY input_buf,JSAMPIMAGE output_buf,JDIMENSION output_row,int num_rows)282 grayscale_convert (j_compress_ptr cinfo,
283 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
284 JDIMENSION output_row, int num_rows)
285 {
286 register JSAMPROW inptr;
287 register JSAMPROW outptr;
288 register JDIMENSION col;
289 JDIMENSION num_cols = cinfo->image_width;
290 int instride = cinfo->input_components;
291
292 while (--num_rows >= 0) {
293 inptr = *input_buf++;
294 outptr = output_buf[0][output_row];
295 output_row++;
296 for (col = 0; col < num_cols; col++) {
297 outptr[col] = inptr[0]; /* don't need GETJSAMPLE() here */
298 inptr += instride;
299 }
300 }
301 }
302
303 #ifdef ENABLE_ANDROID_NULL_CONVERT
304
305 typedef unsigned long UINT32;
306
307 #define B0(n) ((n) & 0xFF)
308 #define B1(n) (((n) >> 8) & 0xFF)
309 #define B2(n) (((n) >> 16) & 0xFF)
310 #define B3(n) ((n) >> 24)
311
312 #define PACK(a, b, c, d) ((a) | ((b) << 8) | ((c) << 16) | ((d) << 24))
313
ptr_is_quad(const void * p)314 static int ptr_is_quad(const void* p)
315 {
316 return (((const char*)p - (const char*)0) & 3) == 0;
317 }
318
copyquads(const UINT32 in[],UINT32 out0[],UINT32 out1[],UINT32 out2[],int col4)319 static void copyquads(const UINT32 in[], UINT32 out0[], UINT32 out1[], UINT32 out2[], int col4)
320 {
321 do {
322 UINT32 src0 = *in++;
323 UINT32 src1 = *in++;
324 UINT32 src2 = *in++;
325 // LEndian
326 *out0++ = PACK(B0(src0), B3(src0), B2(src1), B1(src2));
327 *out1++ = PACK(B1(src0), B0(src1), B3(src1), B2(src2));
328 *out2++ = PACK(B2(src0), B1(src1), B0(src2), B3(src2));
329 } while (--col4 != 0);
330 }
331
332 #endif
333
334 /*
335 * Convert some rows of samples to the JPEG colorspace.
336 * This version handles multi-component colorspaces without conversion.
337 * We assume input_components == num_components.
338 */
339
340 METHODDEF(void)
null_convert(j_compress_ptr cinfo,JSAMPARRAY input_buf,JSAMPIMAGE output_buf,JDIMENSION output_row,int num_rows)341 null_convert (j_compress_ptr cinfo,
342 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
343 JDIMENSION output_row, int num_rows)
344 {
345 register JSAMPROW inptr;
346 register JSAMPROW outptr;
347 register JDIMENSION col;
348 register int ci;
349 int nc = cinfo->num_components;
350 JDIMENSION num_cols = cinfo->image_width;
351
352 #ifdef ENABLE_ANDROID_NULL_CONVERT
353 if (1 == num_rows && 3 == nc && num_cols > 0) {
354 JSAMPROW inptr = *input_buf;
355 JSAMPROW outptr0 = output_buf[0][output_row];
356 JSAMPROW outptr1 = output_buf[1][output_row];
357 JSAMPROW outptr2 = output_buf[2][output_row];
358
359 int col = num_cols;
360 int col4 = col >> 2;
361 if (col4 > 0 && ptr_is_quad(inptr) && ptr_is_quad(outptr0) &&
362 ptr_is_quad(outptr1) && ptr_is_quad(outptr2)) {
363
364 const UINT32* in = (const UINT32*)inptr;
365 UINT32* out0 = (UINT32*)outptr0;
366 UINT32* out1 = (UINT32*)outptr1;
367 UINT32* out2 = (UINT32*)outptr2;
368 copyquads(in, out0, out1, out2, col4);
369 col &= 3;
370 if (0 == col)
371 return;
372 col4 <<= 2;
373 inptr += col4 * 3; /* we read this 3 times per in copyquads */
374 outptr0 += col4;
375 outptr1 += col4;
376 outptr2 += col4;
377 /* fall through to while-loop */
378 }
379 do {
380 *outptr0++ = *inptr++;
381 *outptr1++ = *inptr++;
382 *outptr2++ = *inptr++;
383 } while (--col != 0);
384 return;
385 }
386 SLOW:
387 #endif
388 while (--num_rows >= 0) {
389 /* It seems fastest to make a separate pass for each component. */
390 for (ci = 0; ci < nc; ci++) {
391 inptr = *input_buf;
392 outptr = output_buf[ci][output_row];
393 for (col = 0; col < num_cols; col++) {
394 outptr[col] = inptr[ci]; /* don't need GETJSAMPLE() here */
395 inptr += nc;
396 }
397 }
398 input_buf++;
399 output_row++;
400 }
401 }
402
403
404 /*
405 * Empty method for start_pass.
406 */
407
408 METHODDEF(void)
null_method(j_compress_ptr cinfo)409 null_method (j_compress_ptr cinfo)
410 {
411 /* no work needed */
412 }
413
414
415 /*
416 * Module initialization routine for input colorspace conversion.
417 */
418
419 GLOBAL(void)
jinit_color_converter(j_compress_ptr cinfo)420 jinit_color_converter (j_compress_ptr cinfo)
421 {
422 my_cconvert_ptr cconvert;
423
424 cconvert = (my_cconvert_ptr)
425 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
426 SIZEOF(my_color_converter));
427 cinfo->cconvert = (struct jpeg_color_converter *) cconvert;
428 /* set start_pass to null method until we find out differently */
429 cconvert->pub.start_pass = null_method;
430
431 /* Make sure input_components agrees with in_color_space */
432 switch (cinfo->in_color_space) {
433 case JCS_GRAYSCALE:
434 if (cinfo->input_components != 1)
435 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
436 break;
437
438 case JCS_RGB:
439 #if RGB_PIXELSIZE != 3
440 if (cinfo->input_components != RGB_PIXELSIZE)
441 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
442 break;
443 #endif /* else share code with YCbCr */
444
445 case JCS_YCbCr:
446 if (cinfo->input_components != 3)
447 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
448 break;
449
450 case JCS_CMYK:
451 case JCS_YCCK:
452 if (cinfo->input_components != 4)
453 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
454 break;
455
456 default: /* JCS_UNKNOWN can be anything */
457 if (cinfo->input_components < 1)
458 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
459 break;
460 }
461
462 /* Check num_components, set conversion method based on requested space */
463 switch (cinfo->jpeg_color_space) {
464 case JCS_GRAYSCALE:
465 if (cinfo->num_components != 1)
466 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
467 if (cinfo->in_color_space == JCS_GRAYSCALE)
468 cconvert->pub.color_convert = grayscale_convert;
469 else if (cinfo->in_color_space == JCS_RGB) {
470 cconvert->pub.start_pass = rgb_ycc_start;
471 cconvert->pub.color_convert = rgb_gray_convert;
472 } else if (cinfo->in_color_space == JCS_YCbCr)
473 cconvert->pub.color_convert = grayscale_convert;
474 else
475 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
476 break;
477
478 case JCS_RGB:
479 if (cinfo->num_components != 3)
480 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
481 if (cinfo->in_color_space == JCS_RGB && RGB_PIXELSIZE == 3)
482 cconvert->pub.color_convert = null_convert;
483 else
484 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
485 break;
486
487 case JCS_YCbCr:
488 if (cinfo->num_components != 3)
489 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
490 if (cinfo->in_color_space == JCS_RGB) {
491 cconvert->pub.start_pass = rgb_ycc_start;
492 cconvert->pub.color_convert = rgb_ycc_convert;
493 } else if (cinfo->in_color_space == JCS_YCbCr)
494 cconvert->pub.color_convert = null_convert;
495 else
496 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
497 break;
498
499 case JCS_CMYK:
500 if (cinfo->num_components != 4)
501 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
502 if (cinfo->in_color_space == JCS_CMYK)
503 cconvert->pub.color_convert = null_convert;
504 else
505 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
506 break;
507
508 case JCS_YCCK:
509 if (cinfo->num_components != 4)
510 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
511 if (cinfo->in_color_space == JCS_CMYK) {
512 cconvert->pub.start_pass = rgb_ycc_start;
513 cconvert->pub.color_convert = cmyk_ycck_convert;
514 } else if (cinfo->in_color_space == JCS_YCCK)
515 cconvert->pub.color_convert = null_convert;
516 else
517 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
518 break;
519
520 default: /* allow null conversion of JCS_UNKNOWN */
521 if (cinfo->jpeg_color_space != cinfo->in_color_space ||
522 cinfo->num_components != cinfo->input_components)
523 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
524 cconvert->pub.color_convert = null_convert;
525 break;
526 }
527 }
528