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 } 732