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) 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) 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) 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) 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) 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)) 313 314 static int ptr_is_quad(const void* p) 315 { 316 return (((const char*)p - (const char*)0) & 3) == 0; 317 } 318 319 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) 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) 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) 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
