media/libjpeg/jdcolor.c

   1 /*
   2  * jdcolor.c
   3  *
   4  * This file was part of the Independent JPEG Group's software:
   5  * Copyright (C) 1991-1997, Thomas G. Lane.
   6  * Modified 2011 by Guido Vollbeding.
   7  * Modifications:
   8  * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
   9  * Copyright (C) 2009, 2011-2012, D. R. Commander.
  10  * For conditions of distribution and use, see the accompanying README file.
  11  *
  12  * This file contains output colorspace conversion routines.
  13  */
  14
  15 #define JPEG_INTERNALS
  16 #include "jinclude.h"
  17 #include "jpeglib.h"
  18 #include "jsimd.h"
  19 #include "config.h"
  20
  21
  22 /* Private subobject */
  23
  24 typedef struct {
  25   struct jpeg_color_deconverter pub; /* public fields */
  26
  27   /* Private state for YCC->RGB conversion */
  28   int * Cr_r_tab;               /* => table for Cr to R conversion */
  29   int * Cb_b_tab;               /* => table for Cb to B conversion */
  30   INT32 * Cr_g_tab;             /* => table for Cr to G conversion */
  31   INT32 * Cb_g_tab;             /* => table for Cb to G conversion */
  32
  33   /* Private state for RGB->Y conversion */
  34   INT32 * rgb_y_tab;            /* => table for RGB to Y conversion */
  35 } my_color_deconverter;
  36
  37 typedef my_color_deconverter * my_cconvert_ptr;
  38
  39
  40 /**************** YCbCr -> RGB conversion: most common case **************/
  41 /****************   RGB -> Y   conversion: less common case **************/
  42
  43 /*
  44  * YCbCr is defined per CCIR 601-1, except that Cb and Cr are
  45  * normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
  46  * The conversion equations to be implemented are therefore
  47  *
  48  *      R = Y                + 1.40200 * Cr
  49  *      G = Y - 0.34414 * Cb - 0.71414 * Cr
  50  *      B = Y + 1.77200 * Cb
  51  *
  52  *      Y = 0.29900 * R + 0.58700 * G + 0.11400 * B
  53  *
  54  * where Cb and Cr represent the incoming values less CENTERJSAMPLE.
  55  * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.)
  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  * Notice that Y, being an integral input, does not contribute any fraction
  61  * so it need not participate in the rounding.
  62  *
  63  * For even more speed, we avoid doing any multiplications in the inner loop
  64  * by precalculating the constants times Cb and Cr for all possible values.
  65  * For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table);
  66  * for 12-bit samples it is still acceptable.  It's not very reasonable for
  67  * 16-bit samples, but if you want lossless storage you shouldn't be changing
  68  * colorspace anyway.
  69  * The Cr=>R and Cb=>B values can be rounded to integers in advance; the
  70  * values for the G calculation are left scaled up, since we must add them
  71  * together before rounding.
  72  */
  73
  74 #define SCALEBITS       16      /* speediest right-shift on some machines */
  75 #define ONE_HALF        ((INT32) 1 << (SCALEBITS-1))
  76 #define FIX(x)          ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
  77
  78 /* We allocate one big table for RGB->Y conversion and divide it up into
  79  * three parts, instead of doing three alloc_small requests.  This lets us
  80  * use a single table base address, which can be held in a register in the
  81  * inner loops on many machines (more than can hold all three addresses,
  82  * anyway).
  83  */
  84
  85 #define R_Y_OFF         0                       /* offset to R => Y section */
  86 #define G_Y_OFF         (1*(MAXJSAMPLE+1))      /* offset to G => Y section */
  87 #define B_Y_OFF         (2*(MAXJSAMPLE+1))      /* etc. */
  88 #define TABLE_SIZE      (3*(MAXJSAMPLE+1))
  89
  90
  91 /* Include inline routines for colorspace extensions */
  92
  93 #include "jdcolext.c"
  94 #undef RGB_RED
  95 #undef RGB_GREEN
  96 #undef RGB_BLUE
  97 #undef RGB_PIXELSIZE
  98
  99 #define RGB_RED EXT_RGB_RED
 100 #define RGB_GREEN EXT_RGB_GREEN
 101 #define RGB_BLUE EXT_RGB_BLUE
 102 #define RGB_PIXELSIZE EXT_RGB_PIXELSIZE
 103 #define ycc_rgb_convert_internal ycc_extrgb_convert_internal
 104 #define gray_rgb_convert_internal gray_extrgb_convert_internal
 105 #define rgb_rgb_convert_internal rgb_extrgb_convert_internal
 106 #include "jdcolext.c"
 107 #undef RGB_RED
 108 #undef RGB_GREEN
 109 #undef RGB_BLUE
 110 #undef RGB_PIXELSIZE
 111 #undef ycc_rgb_convert_internal
 112 #undef gray_rgb_convert_internal
 113 #undef rgb_rgb_convert_internal
 114
 115 #define RGB_RED EXT_RGBX_RED
 116 #define RGB_GREEN EXT_RGBX_GREEN
 117 #define RGB_BLUE EXT_RGBX_BLUE
 118 #define RGB_ALPHA 3
 119 #define RGB_PIXELSIZE EXT_RGBX_PIXELSIZE
 120 #define ycc_rgb_convert_internal ycc_extrgbx_convert_internal
 121 #define gray_rgb_convert_internal gray_extrgbx_convert_internal
 122 #define rgb_rgb_convert_internal rgb_extrgbx_convert_internal
 123 #include "jdcolext.c"
 124 #undef RGB_RED
 125 #undef RGB_GREEN
 126 #undef RGB_BLUE
 127 #undef RGB_ALPHA
 128 #undef RGB_PIXELSIZE
 129 #undef ycc_rgb_convert_internal
 130 #undef gray_rgb_convert_internal
 131 #undef rgb_rgb_convert_internal
 132
 133 #define RGB_RED EXT_BGR_RED
 134 #define RGB_GREEN EXT_BGR_GREEN
 135 #define RGB_BLUE EXT_BGR_BLUE
 136 #define RGB_PIXELSIZE EXT_BGR_PIXELSIZE
 137 #define ycc_rgb_convert_internal ycc_extbgr_convert_internal
 138 #define gray_rgb_convert_internal gray_extbgr_convert_internal
 139 #define rgb_rgb_convert_internal rgb_extbgr_convert_internal
 140 #include "jdcolext.c"
 141 #undef RGB_RED
 142 #undef RGB_GREEN
 143 #undef RGB_BLUE
 144 #undef RGB_PIXELSIZE
 145 #undef ycc_rgb_convert_internal
 146 #undef gray_rgb_convert_internal
 147 #undef rgb_rgb_convert_internal
 148
 149 #define RGB_RED EXT_BGRX_RED
 150 #define RGB_GREEN EXT_BGRX_GREEN
 151 #define RGB_BLUE EXT_BGRX_BLUE
 152 #define RGB_ALPHA 3
 153 #define RGB_PIXELSIZE EXT_BGRX_PIXELSIZE
 154 #define ycc_rgb_convert_internal ycc_extbgrx_convert_internal
 155 #define gray_rgb_convert_internal gray_extbgrx_convert_internal
 156 #define rgb_rgb_convert_internal rgb_extbgrx_convert_internal
 157 #include "jdcolext.c"
 158 #undef RGB_RED
 159 #undef RGB_GREEN
 160 #undef RGB_BLUE
 161 #undef RGB_ALPHA
 162 #undef RGB_PIXELSIZE
 163 #undef ycc_rgb_convert_internal
 164 #undef gray_rgb_convert_internal
 165 #undef rgb_rgb_convert_internal
 166
 167 #define RGB_RED EXT_XBGR_RED
 168 #define RGB_GREEN EXT_XBGR_GREEN
 169 #define RGB_BLUE EXT_XBGR_BLUE
 170 #define RGB_ALPHA 0
 171 #define RGB_PIXELSIZE EXT_XBGR_PIXELSIZE
 172 #define ycc_rgb_convert_internal ycc_extxbgr_convert_internal
 173 #define gray_rgb_convert_internal gray_extxbgr_convert_internal
 174 #define rgb_rgb_convert_internal rgb_extxbgr_convert_internal
 175 #include "jdcolext.c"
 176 #undef RGB_RED
 177 #undef RGB_GREEN
 178 #undef RGB_BLUE
 179 #undef RGB_ALPHA
 180 #undef RGB_PIXELSIZE
 181 #undef ycc_rgb_convert_internal
 182 #undef gray_rgb_convert_internal
 183 #undef rgb_rgb_convert_internal
 184
 185 #define RGB_RED EXT_XRGB_RED
 186 #define RGB_GREEN EXT_XRGB_GREEN
 187 #define RGB_BLUE EXT_XRGB_BLUE
 188 #define RGB_ALPHA 0
 189 #define RGB_PIXELSIZE EXT_XRGB_PIXELSIZE
 190 #define ycc_rgb_convert_internal ycc_extxrgb_convert_internal
 191 #define gray_rgb_convert_internal gray_extxrgb_convert_internal
 192 #define rgb_rgb_convert_internal rgb_extxrgb_convert_internal
 193 #include "jdcolext.c"
 194 #undef RGB_RED
 195 #undef RGB_GREEN
 196 #undef RGB_BLUE
 197 #undef RGB_ALPHA
 198 #undef RGB_PIXELSIZE
 199 #undef ycc_rgb_convert_internal
 200 #undef gray_rgb_convert_internal
 201 #undef rgb_rgb_convert_internal
 202
 203
 204 /*
 205  * Initialize tables for YCC->RGB colorspace conversion.
 206  */
 207
 208 LOCAL(void)
 209 build_ycc_rgb_table (j_decompress_ptr cinfo)
 210 {
 211   my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
 212   int i;
 213   INT32 x;
 214   SHIFT_TEMPS
 215
 216   cconvert->Cr_r_tab = (int *)
 217     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 218                                 (MAXJSAMPLE+1) * SIZEOF(int));
 219   cconvert->Cb_b_tab = (int *)
 220     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 221                                 (MAXJSAMPLE+1) * SIZEOF(int));
 222   cconvert->Cr_g_tab = (INT32 *)
 223     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 224                                 (MAXJSAMPLE+1) * SIZEOF(INT32));
 225   cconvert->Cb_g_tab = (INT32 *)
 226     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 227                                 (MAXJSAMPLE+1) * SIZEOF(INT32));
 228
 229   for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
 230     /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
 231     /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
 232     /* Cr=>R value is nearest int to 1.40200 * x */
 233     cconvert->Cr_r_tab[i] = (int)
 234                     RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS);
 235     /* Cb=>B value is nearest int to 1.77200 * x */
 236     cconvert->Cb_b_tab[i] = (int)
 237                     RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS);
 238     /* Cr=>G value is scaled-up -0.71414 * x */
 239     cconvert->Cr_g_tab[i] = (- FIX(0.71414)) * x;
 240     /* Cb=>G value is scaled-up -0.34414 * x */
 241     /* We also add in ONE_HALF so that need not do it in inner loop */
 242     cconvert->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF;
 243   }
 244 }
 245
 246
 247 /*
 248  * Convert some rows of samples to the output colorspace.
 249  */
 250
 251 METHODDEF(void)
 252 ycc_rgb_convert (j_decompress_ptr cinfo,
 253                  JSAMPIMAGE input_buf, JDIMENSION input_row,
 254                  JSAMPARRAY output_buf, int num_rows)
 255 {
 256   switch (cinfo->out_color_space) {
 257     case JCS_EXT_RGB:
 258       ycc_extrgb_convert_internal(cinfo, input_buf, input_row, output_buf,
 259                                   num_rows);
 260       break;
 261     case JCS_EXT_RGBX:
 262     case JCS_EXT_RGBA:
 263       ycc_extrgbx_convert_internal(cinfo, input_buf, input_row, output_buf,
 264                                    num_rows);
 265       break;
 266     case JCS_EXT_BGR:
 267       ycc_extbgr_convert_internal(cinfo, input_buf, input_row, output_buf,
 268                                   num_rows);
 269       break;
 270     case JCS_EXT_BGRX:
 271     case JCS_EXT_BGRA:
 272       ycc_extbgrx_convert_internal(cinfo, input_buf, input_row, output_buf,
 273                                    num_rows);
 274       break;
 275     case JCS_EXT_XBGR:
 276     case JCS_EXT_ABGR:
 277       ycc_extxbgr_convert_internal(cinfo, input_buf, input_row, output_buf,
 278                                    num_rows);
 279       break;
 280     case JCS_EXT_XRGB:
 281     case JCS_EXT_ARGB:
 282       ycc_extxrgb_convert_internal(cinfo, input_buf, input_row, output_buf,
 283                                    num_rows);
 284       break;
 285     default:
 286       ycc_rgb_convert_internal(cinfo, input_buf, input_row, output_buf,
 287                                num_rows);
 288       break;
 289   }
 290 }
 291
 292
 293 /**************** Cases other than YCbCr -> RGB **************/
 294
 295
 296 /*
 297  * Initialize for RGB->grayscale colorspace conversion.
 298  */
 299
 300 LOCAL(void)
 301 build_rgb_y_table (j_decompress_ptr cinfo)
 302 {
 303   my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
 304   INT32 * rgb_y_tab;
 305   INT32 i;
 306
 307   /* Allocate and fill in the conversion tables. */
 308   cconvert->rgb_y_tab = rgb_y_tab = (INT32 *)
 309     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 310                                 (TABLE_SIZE * SIZEOF(INT32)));
 311
 312   for (i = 0; i <= MAXJSAMPLE; i++) {
 313     rgb_y_tab[i+R_Y_OFF] = FIX(0.29900) * i;
 314     rgb_y_tab[i+G_Y_OFF] = FIX(0.58700) * i;
 315     rgb_y_tab[i+B_Y_OFF] = FIX(0.11400) * i + ONE_HALF;
 316   }
 317 }
 318
 319
 320 /*
 321  * Convert RGB to grayscale.
 322  */
 323
 324 METHODDEF(void)
 325 rgb_gray_convert (j_decompress_ptr cinfo,
 326                   JSAMPIMAGE input_buf, JDIMENSION input_row,
 327                   JSAMPARRAY output_buf, int num_rows)
 328 {
 329   my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
 330   register int r, g, b;
 331   register INT32 * ctab = cconvert->rgb_y_tab;
 332   register JSAMPROW outptr;
 333   register JSAMPROW inptr0, inptr1, inptr2;
 334   register JDIMENSION col;
 335   JDIMENSION num_cols = cinfo->output_width;
 336
 337   while (--num_rows >= 0) {
 338     inptr0 = input_buf[0][input_row];
 339     inptr1 = input_buf[1][input_row];
 340     inptr2 = input_buf[2][input_row];
 341     input_row++;
 342     outptr = *output_buf++;
 343     for (col = 0; col < num_cols; col++) {
 344       r = GETJSAMPLE(inptr0[col]);
 345       g = GETJSAMPLE(inptr1[col]);
 346       b = GETJSAMPLE(inptr2[col]);
 347       /* Y */
 348       outptr[col] = (JSAMPLE)
 349                 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
 350                  >> SCALEBITS);
 351     }
 352   }
 353 }
 354
 355
 356 /*
 357  * Color conversion for no colorspace change: just copy the data,
 358  * converting from separate-planes to interleaved representation.
 359  */
 360
 361 METHODDEF(void)
 362 null_convert (j_decompress_ptr cinfo,
 363               JSAMPIMAGE input_buf, JDIMENSION input_row,
 364               JSAMPARRAY output_buf, int num_rows)
 365 {
 366   register JSAMPROW inptr, outptr;
 367   register JDIMENSION count;
 368   register int num_components = cinfo->num_components;
 369   JDIMENSION num_cols = cinfo->output_width;
 370   int ci;
 371
 372   while (--num_rows >= 0) {
 373     for (ci = 0; ci < num_components; ci++) {
 374       inptr = input_buf[ci][input_row];
 375       outptr = output_buf[0] + ci;
 376       for (count = num_cols; count > 0; count--) {
 377         *outptr = *inptr++;     /* needn't bother with GETJSAMPLE() here */
 378         outptr += num_components;
 379       }
 380     }
 381     input_row++;
 382     output_buf++;
 383   }
 384 }
 385
 386
 387 /*
 388  * Color conversion for grayscale: just copy the data.
 389  * This also works for YCbCr -> grayscale conversion, in which
 390  * we just copy the Y (luminance) component and ignore chrominance.
 391  */
 392
 393 METHODDEF(void)
 394 grayscale_convert (j_decompress_ptr cinfo,
 395                    JSAMPIMAGE input_buf, JDIMENSION input_row,
 396                    JSAMPARRAY output_buf, int num_rows)
 397 {
 398   jcopy_sample_rows(input_buf[0], (int) input_row, output_buf, 0,
 399                     num_rows, cinfo->output_width);
 400 }
 401
 402
 403 /*
 404  * Convert grayscale to RGB
 405  */
 406
 407 METHODDEF(void)
 408 gray_rgb_convert (j_decompress_ptr cinfo,
 409                   JSAMPIMAGE input_buf, JDIMENSION input_row,
 410                   JSAMPARRAY output_buf, int num_rows)
 411 {
 412   switch (cinfo->out_color_space) {
 413     case JCS_EXT_RGB:
 414       gray_extrgb_convert_internal(cinfo, input_buf, input_row, output_buf,
 415                                    num_rows);
 416       break;
 417     case JCS_EXT_RGBX:
 418     case JCS_EXT_RGBA:
 419       gray_extrgbx_convert_internal(cinfo, input_buf, input_row, output_buf,
 420                                     num_rows);
 421       break;
 422     case JCS_EXT_BGR:
 423       gray_extbgr_convert_internal(cinfo, input_buf, input_row, output_buf,
 424                                    num_rows);
 425       break;
 426     case JCS_EXT_BGRX:
 427     case JCS_EXT_BGRA:
 428       gray_extbgrx_convert_internal(cinfo, input_buf, input_row, output_buf,
 429                                     num_rows);
 430       break;
 431     case JCS_EXT_XBGR:
 432     case JCS_EXT_ABGR:
 433       gray_extxbgr_convert_internal(cinfo, input_buf, input_row, output_buf,
 434                                     num_rows);
 435       break;
 436     case JCS_EXT_XRGB:
 437     case JCS_EXT_ARGB:
 438       gray_extxrgb_convert_internal(cinfo, input_buf, input_row, output_buf,
 439                                     num_rows);
 440       break;
 441     default:
 442       gray_rgb_convert_internal(cinfo, input_buf, input_row, output_buf,
 443                                 num_rows);
 444       break;
 445   }
 446 }
 447
 448
 449 /*
 450  * Convert plain RGB to extended RGB
 451  */
 452
 453 METHODDEF(void)
 454 rgb_rgb_convert (j_decompress_ptr cinfo,
 455                   JSAMPIMAGE input_buf, JDIMENSION input_row,
 456                   JSAMPARRAY output_buf, int num_rows)
 457 {
 458   switch (cinfo->out_color_space) {
 459     case JCS_EXT_RGB:
 460       rgb_extrgb_convert_internal(cinfo, input_buf, input_row, output_buf,
 461                                   num_rows);
 462       break;
 463     case JCS_EXT_RGBX:
 464     case JCS_EXT_RGBA:
 465       rgb_extrgbx_convert_internal(cinfo, input_buf, input_row, output_buf,
 466                                    num_rows);
 467       break;
 468     case JCS_EXT_BGR:
 469       rgb_extbgr_convert_internal(cinfo, input_buf, input_row, output_buf,
 470                                   num_rows);
 471       break;
 472     case JCS_EXT_BGRX:
 473     case JCS_EXT_BGRA:
 474       rgb_extbgrx_convert_internal(cinfo, input_buf, input_row, output_buf,
 475                                    num_rows);
 476       break;
 477     case JCS_EXT_XBGR:
 478     case JCS_EXT_ABGR:
 479       rgb_extxbgr_convert_internal(cinfo, input_buf, input_row, output_buf,
 480                                    num_rows);
 481       break;
 482     case JCS_EXT_XRGB:
 483     case JCS_EXT_ARGB:
 484       rgb_extxrgb_convert_internal(cinfo, input_buf, input_row, output_buf,
 485                                    num_rows);
 486       break;
 487     default:
 488       rgb_rgb_convert_internal(cinfo, input_buf, input_row, output_buf,
 489                                num_rows);
 490       break;
 491   }
 492 }
 493
 494
 495 /*
 496  * Adobe-style YCCK->CMYK conversion.
 497  * We convert YCbCr to R=1-C, G=1-M, and B=1-Y using the same
 498  * conversion as above, while passing K (black) unchanged.
 499  * We assume build_ycc_rgb_table has been called.
 500  */
 501
 502 METHODDEF(void)
 503 ycck_cmyk_convert (j_decompress_ptr cinfo,
 504                    JSAMPIMAGE input_buf, JDIMENSION input_row,
 505                    JSAMPARRAY output_buf, int num_rows)
 506 {
 507   my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
 508   register int y, cb, cr;
 509   register JSAMPROW outptr;
 510   register JSAMPROW inptr0, inptr1, inptr2, inptr3;
 511   register JDIMENSION col;
 512   JDIMENSION num_cols = cinfo->output_width;
 513   /* copy these pointers into registers if possible */
 514   register JSAMPLE * range_limit = cinfo->sample_range_limit;
 515   register int * Crrtab = cconvert->Cr_r_tab;
 516   register int * Cbbtab = cconvert->Cb_b_tab;
 517   register INT32 * Crgtab = cconvert->Cr_g_tab;
 518   register INT32 * Cbgtab = cconvert->Cb_g_tab;
 519   SHIFT_TEMPS
 520
 521   while (--num_rows >= 0) {
 522     inptr0 = input_buf[0][input_row];
 523     inptr1 = input_buf[1][input_row];
 524     inptr2 = input_buf[2][input_row];
 525     inptr3 = input_buf[3][input_row];
 526     input_row++;
 527     outptr = *output_buf++;
 528     for (col = 0; col < num_cols; col++) {
 529       y  = GETJSAMPLE(inptr0[col]);
 530       cb = GETJSAMPLE(inptr1[col]);
 531       cr = GETJSAMPLE(inptr2[col]);
 532       /* Range-limiting is essential due to noise introduced by DCT losses. */
 533       outptr[0] = range_limit[MAXJSAMPLE - (y + Crrtab[cr])];   /* red */
 534       outptr[1] = range_limit[MAXJSAMPLE - (y +                 /* green */
 535                               ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr],
 536                                                  SCALEBITS)))];
 537       outptr[2] = range_limit[MAXJSAMPLE - (y + Cbbtab[cb])];   /* blue */
 538       /* K passes through unchanged */
 539       outptr[3] = inptr3[col];  /* don't need GETJSAMPLE here */
 540       outptr += 4;
 541     }
 542   }
 543 }
 544
 545
 546 /*
 547  * Empty method for start_pass.
 548  */
 549
 550 METHODDEF(void)
 551 start_pass_dcolor (j_decompress_ptr cinfo)
 552 {
 553   /* no work needed */
 554 }
 555
 556
 557 /*
 558  * Module initialization routine for output colorspace conversion.
 559  */
 560
 561 GLOBAL(void)
 562 jinit_color_deconverter (j_decompress_ptr cinfo)
 563 {
 564   my_cconvert_ptr cconvert;
 565   int ci;
 566
 567   cconvert = (my_cconvert_ptr)
 568     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 569                                 SIZEOF(my_color_deconverter));
 570   cinfo->cconvert = (struct jpeg_color_deconverter *) cconvert;
 571   cconvert->pub.start_pass = start_pass_dcolor;
 572
 573   /* Make sure num_components agrees with jpeg_color_space */
 574   switch (cinfo->jpeg_color_space) {
 575   case JCS_GRAYSCALE:
 576     if (cinfo->num_components != 1)
 577       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
 578     break;
 579
 580   case JCS_RGB:
 581   case JCS_YCbCr:
 582     if (cinfo->num_components != 3)
 583       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
 584     break;
 585
 586   case JCS_CMYK:
 587   case JCS_YCCK:
 588     if (cinfo->num_components != 4)
 589       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
 590     break;
 591
 592   default:                      /* JCS_UNKNOWN can be anything */
 593     if (cinfo->num_components < 1)
 594       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
 595     break;
 596   }
 597
 598   /* Set out_color_components and conversion method based on requested space.
 599    * Also clear the component_needed flags for any unused components,
 600    * so that earlier pipeline stages can avoid useless computation.
 601    */
 602
 603   switch (cinfo->out_color_space) {
 604   case JCS_GRAYSCALE:
 605     cinfo->out_color_components = 1;
 606     if (cinfo->jpeg_color_space == JCS_GRAYSCALE ||
 607         cinfo->jpeg_color_space == JCS_YCbCr) {
 608       cconvert->pub.color_convert = grayscale_convert;
 609       /* For color->grayscale conversion, only the Y (0) component is needed */
 610       for (ci = 1; ci < cinfo->num_components; ci++)
 611         cinfo->comp_info[ci].component_needed = FALSE;
 612     } else if (cinfo->jpeg_color_space == JCS_RGB) {
 613       cconvert->pub.color_convert = rgb_gray_convert;
 614       build_rgb_y_table(cinfo);
 615     } else
 616       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
 617     break;
 618
 619   case JCS_RGB:
 620   case JCS_EXT_RGB:
 621   case JCS_EXT_RGBX:
 622   case JCS_EXT_BGR:
 623   case JCS_EXT_BGRX:
 624   case JCS_EXT_XBGR:
 625   case JCS_EXT_XRGB:
 626   case JCS_EXT_RGBA:
 627   case JCS_EXT_BGRA:
 628   case JCS_EXT_ABGR:
 629   case JCS_EXT_ARGB:
 630     cinfo->out_color_components = rgb_pixelsize[cinfo->out_color_space];
 631     if (cinfo->jpeg_color_space == JCS_YCbCr) {
 632       if (jsimd_can_ycc_rgb())
 633         cconvert->pub.color_convert = jsimd_ycc_rgb_convert;
 634       else {
 635         cconvert->pub.color_convert = ycc_rgb_convert;
 636         build_ycc_rgb_table(cinfo);
 637       }
 638     } else if (cinfo->jpeg_color_space == JCS_GRAYSCALE) {
 639       cconvert->pub.color_convert = gray_rgb_convert;
 640     } else if (cinfo->jpeg_color_space == JCS_RGB) {
 641       if (rgb_red[cinfo->out_color_space] == 0 &&
 642           rgb_green[cinfo->out_color_space] == 1 &&
 643           rgb_blue[cinfo->out_color_space] == 2 &&
 644           rgb_pixelsize[cinfo->out_color_space] == 3)
 645         cconvert->pub.color_convert = null_convert;
 646       else
 647         cconvert->pub.color_convert = rgb_rgb_convert;
 648     } else
 649       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
 650     break;
 651
 652   case JCS_CMYK:
 653     cinfo->out_color_components = 4;
 654     if (cinfo->jpeg_color_space == JCS_YCCK) {
 655       cconvert->pub.color_convert = ycck_cmyk_convert;
 656       build_ycc_rgb_table(cinfo);
 657     } else if (cinfo->jpeg_color_space == JCS_CMYK) {
 658       cconvert->pub.color_convert = null_convert;
 659     } else
 660       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
 661     break;
 662
 663   default:
 664     /* Permit null conversion to same output space */
 665     if (cinfo->out_color_space == cinfo->jpeg_color_space) {
 666       cinfo->out_color_components = cinfo->num_components;
 667       cconvert->pub.color_convert = null_convert;
 668     } else                      /* unsupported non-null conversion */
 669       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
 670     break;
 671   }
 672
 673   if (cinfo->quantize_colors)
 674     cinfo->output_components = 1; /* single colormapped output component */
 675   else
 676     cinfo->output_components = cinfo->out_color_components;
 677 }