1 #if !defined(_FX_JPEG_TURBO_) 2 /* 3 * jdcolor.c 4 * 5 * Copyright (C) 1991-1997, Thomas G. Lane. 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 /* Private subobject */ 18 19 typedef struct { 20 struct jpeg_color_deconverter pub; /* public fields */ 21 22 /* Private state for YCC->RGB conversion */ 23 int * Cr_r_tab; /* => table for Cr to R conversion */ 24 int * Cb_b_tab; /* => table for Cb to B conversion */ 25 INT32 * Cr_g_tab; /* => table for Cr to G conversion */ 26 INT32 * Cb_g_tab; /* => table for Cb to G conversion */ 27 } my_color_deconverter; 28 29 typedef my_color_deconverter * my_cconvert_ptr; 30 31 32 /**************** YCbCr -> RGB conversion: most common case **************/ 33 34 /* 35 * YCbCr is defined per CCIR 601-1, except that Cb and Cr are 36 * normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5. 37 * The conversion equations to be implemented are therefore 38 * R = Y + 1.40200 * Cr 39 * G = Y - 0.34414 * Cb - 0.71414 * Cr 40 * B = Y + 1.77200 * Cb 41 * where Cb and Cr represent the incoming values less CENTERJSAMPLE. 42 * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.) 43 * 44 * To avoid floating-point arithmetic, we represent the fractional constants 45 * as integers scaled up by 2^16 (about 4 digits precision); we have to divide 46 * the products by 2^16, with appropriate rounding, to get the correct answer. 47 * Notice that Y, being an integral input, does not contribute any fraction 48 * so it need not participate in the rounding. 49 * 50 * For even more speed, we avoid doing any multiplications in the inner loop 51 * by precalculating the constants times Cb and Cr 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 Cr=>R and Cb=>B values can be rounded to integers in advance; the 57 * values for the G calculation are left scaled up, since we must add them 58 * together before rounding. 59 */ 60 61 #define SCALEBITS 16 /* speediest right-shift on some machines */ 62 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1)) 63 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5)) 64 65 66 /* 67 * Initialize tables for YCC->RGB colorspace conversion. 68 */ 69 70 LOCAL(void) 71 build_ycc_rgb_table (j_decompress_ptr cinfo) 72 { 73 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; 74 int i; 75 INT32 x; 76 SHIFT_TEMPS 77 78 cconvert->Cr_r_tab = (int *) 79 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 80 (MAXJSAMPLE+1) * SIZEOF(int)); 81 cconvert->Cb_b_tab = (int *) 82 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 83 (MAXJSAMPLE+1) * SIZEOF(int)); 84 cconvert->Cr_g_tab = (INT32 *) 85 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 86 (MAXJSAMPLE+1) * SIZEOF(INT32)); 87 cconvert->Cb_g_tab = (INT32 *) 88 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 89 (MAXJSAMPLE+1) * SIZEOF(INT32)); 90 91 for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) { 92 /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */ 93 /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */ 94 /* Cr=>R value is nearest int to 1.40200 * x */ 95 cconvert->Cr_r_tab[i] = (int) 96 RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS); 97 /* Cb=>B value is nearest int to 1.77200 * x */ 98 cconvert->Cb_b_tab[i] = (int) 99 RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS); 100 /* Cr=>G value is scaled-up -0.71414 * x */ 101 cconvert->Cr_g_tab[i] = (- FIX(0.71414)) * x; 102 /* Cb=>G value is scaled-up -0.34414 * x */ 103 /* We also add in ONE_HALF so that need not do it in inner loop */ 104 cconvert->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF; 105 } 106 } 107 108 109 /* 110 * Convert some rows of samples to the output colorspace. 111 * 112 * Note that we change from noninterleaved, one-plane-per-component format 113 * to interleaved-pixel format. The output buffer is therefore three times 114 * as wide as the input buffer. 115 * A starting row offset is provided only for the input buffer. The caller 116 * can easily adjust the passed output_buf value to accommodate any row 117 * offset required on that side. 118 */ 119 120 METHODDEF(void) 121 ycc_rgb_convert (j_decompress_ptr cinfo, 122 JSAMPIMAGE input_buf, JDIMENSION input_row, 123 JSAMPARRAY output_buf, int num_rows) 124 { 125 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; 126 register int y, cb, cr; 127 register JSAMPROW outptr; 128 register JSAMPROW inptr0, inptr1, inptr2; 129 register JDIMENSION col; 130 JDIMENSION num_cols = cinfo->output_width; 131 /* copy these pointers into registers if possible */ 132 register JSAMPLE * range_limit = cinfo->sample_range_limit; 133 register int * Crrtab = cconvert->Cr_r_tab; 134 register int * Cbbtab = cconvert->Cb_b_tab; 135 register INT32 * Crgtab = cconvert->Cr_g_tab; 136 register INT32 * Cbgtab = cconvert->Cb_g_tab; 137 SHIFT_TEMPS 138 139 while (--num_rows >= 0) { 140 inptr0 = input_buf[0][input_row]; 141 inptr1 = input_buf[1][input_row]; 142 inptr2 = input_buf[2][input_row]; 143 input_row++; 144 outptr = *output_buf++; 145 for (col = 0; col < num_cols; col++) { 146 y = GETJSAMPLE(inptr0[col]); 147 cb = GETJSAMPLE(inptr1[col]); 148 cr = GETJSAMPLE(inptr2[col]); 149 /* Range-limiting is essential due to noise introduced by DCT losses. */ 150 outptr[RGB_RED] = range_limit[y + Crrtab[cr]]; 151 outptr[RGB_GREEN] = range_limit[y + 152 ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], 153 SCALEBITS))]; 154 outptr[RGB_BLUE] = range_limit[y + Cbbtab[cb]]; 155 outptr += RGB_PIXELSIZE; 156 } 157 } 158 } 159 160 161 /**************** Cases other than YCbCr -> RGB **************/ 162 163 164 /* 165 * Color conversion for no colorspace change: just copy the data, 166 * converting from separate-planes to interleaved representation. 167 */ 168 169 METHODDEF(void) 170 null_convert (j_decompress_ptr cinfo, 171 JSAMPIMAGE input_buf, JDIMENSION input_row, 172 JSAMPARRAY output_buf, int num_rows) 173 { 174 register JSAMPROW inptr, outptr; 175 register JDIMENSION count; 176 register int num_components = cinfo->num_components; 177 JDIMENSION num_cols = cinfo->output_width; 178 int ci; 179 180 while (--num_rows >= 0) { 181 for (ci = 0; ci < num_components; ci++) { 182 inptr = input_buf[ci][input_row]; 183 outptr = output_buf[0] + ci; 184 for (count = num_cols; count > 0; count--) { 185 *outptr = *inptr++; /* needn't bother with GETJSAMPLE() here */ 186 outptr += num_components; 187 } 188 } 189 input_row++; 190 output_buf++; 191 } 192 } 193 194 195 /* 196 * Color conversion for grayscale: just copy the data. 197 * This also works for YCbCr -> grayscale conversion, in which 198 * we just copy the Y (luminance) component and ignore chrominance. 199 */ 200 201 METHODDEF(void) 202 grayscale_convert (j_decompress_ptr cinfo, 203 JSAMPIMAGE input_buf, JDIMENSION input_row, 204 JSAMPARRAY output_buf, int num_rows) 205 { 206 jcopy_sample_rows(input_buf[0], (int) input_row, output_buf, 0, 207 num_rows, cinfo->output_width); 208 } 209 210 211 /* 212 * Convert grayscale to RGB: just duplicate the graylevel three times. 213 * This is provided to support applications that don't want to cope 214 * with grayscale as a separate case. 215 */ 216 217 METHODDEF(void) 218 gray_rgb_convert (j_decompress_ptr cinfo, 219 JSAMPIMAGE input_buf, JDIMENSION input_row, 220 JSAMPARRAY output_buf, int num_rows) 221 { 222 register JSAMPROW inptr, outptr; 223 register JDIMENSION col; 224 JDIMENSION num_cols = cinfo->output_width; 225 226 while (--num_rows >= 0) { 227 inptr = input_buf[0][input_row++]; 228 outptr = *output_buf++; 229 for (col = 0; col < num_cols; col++) { 230 /* We can dispense with GETJSAMPLE() here */ 231 outptr[RGB_RED] = outptr[RGB_GREEN] = outptr[RGB_BLUE] = inptr[col]; 232 outptr += RGB_PIXELSIZE; 233 } 234 } 235 } 236 237 238 /* 239 * Adobe-style YCCK->CMYK conversion. 240 * We convert YCbCr to R=1-C, G=1-M, and B=1-Y using the same 241 * conversion as above, while passing K (black) unchanged. 242 * We assume build_ycc_rgb_table has been called. 243 */ 244 245 METHODDEF(void) 246 ycck_cmyk_convert (j_decompress_ptr cinfo, 247 JSAMPIMAGE input_buf, JDIMENSION input_row, 248 JSAMPARRAY output_buf, int num_rows) 249 { 250 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; 251 register int y, cb, cr; 252 register JSAMPROW outptr; 253 register JSAMPROW inptr0, inptr1, inptr2, inptr3; 254 register JDIMENSION col; 255 JDIMENSION num_cols = cinfo->output_width; 256 /* copy these pointers into registers if possible */ 257 register JSAMPLE * range_limit = cinfo->sample_range_limit; 258 register int * Crrtab = cconvert->Cr_r_tab; 259 register int * Cbbtab = cconvert->Cb_b_tab; 260 register INT32 * Crgtab = cconvert->Cr_g_tab; 261 register INT32 * Cbgtab = cconvert->Cb_g_tab; 262 SHIFT_TEMPS 263 264 while (--num_rows >= 0) { 265 inptr0 = input_buf[0][input_row]; 266 inptr1 = input_buf[1][input_row]; 267 inptr2 = input_buf[2][input_row]; 268 inptr3 = input_buf[3][input_row]; 269 input_row++; 270 outptr = *output_buf++; 271 for (col = 0; col < num_cols; col++) { 272 y = GETJSAMPLE(inptr0[col]); 273 cb = GETJSAMPLE(inptr1[col]); 274 cr = GETJSAMPLE(inptr2[col]); 275 /* Range-limiting is essential due to noise introduced by DCT losses. */ 276 outptr[0] = range_limit[MAXJSAMPLE - (y + Crrtab[cr])]; /* red */ 277 outptr[1] = range_limit[MAXJSAMPLE - (y + /* green */ 278 ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], 279 SCALEBITS)))]; 280 outptr[2] = range_limit[MAXJSAMPLE - (y + Cbbtab[cb])]; /* blue */ 281 /* K passes through unchanged */ 282 outptr[3] = inptr3[col]; /* don't need GETJSAMPLE here */ 283 outptr += 4; 284 } 285 } 286 } 287 288 289 /* 290 * Empty method for start_pass. 291 */ 292 293 METHODDEF(void) 294 start_pass_dcolor (j_decompress_ptr cinfo) 295 { 296 /* no work needed */ 297 } 298 299 300 /* 301 * Module initialization routine for output colorspace conversion. 302 */ 303 304 GLOBAL(void) 305 jinit_color_deconverter (j_decompress_ptr cinfo) 306 { 307 my_cconvert_ptr cconvert; 308 int ci; 309 310 cconvert = (my_cconvert_ptr) 311 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 312 SIZEOF(my_color_deconverter)); 313 cinfo->cconvert = (struct jpeg_color_deconverter *) cconvert; 314 cconvert->pub.start_pass = start_pass_dcolor; 315 316 /* Make sure num_components agrees with jpeg_color_space */ 317 switch (cinfo->jpeg_color_space) { 318 case JCS_GRAYSCALE: 319 if (cinfo->num_components != 1) 320 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); 321 break; 322 323 case JCS_RGB: 324 case JCS_YCbCr: 325 if (cinfo->num_components != 3) 326 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); 327 break; 328 329 case JCS_CMYK: 330 case JCS_YCCK: 331 if (cinfo->num_components != 4) 332 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); 333 break; 334 335 default: /* JCS_UNKNOWN can be anything */ 336 if (cinfo->num_components < 1) 337 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); 338 break; 339 } 340 341 /* Set out_color_components and conversion method based on requested space. 342 * Also clear the component_needed flags for any unused components, 343 * so that earlier pipeline stages can avoid useless computation. 344 */ 345 346 switch (cinfo->out_color_space) { 347 case JCS_GRAYSCALE: 348 cinfo->out_color_components = 1; 349 if (cinfo->jpeg_color_space == JCS_GRAYSCALE || 350 cinfo->jpeg_color_space == JCS_YCbCr) { 351 cconvert->pub.color_convert = grayscale_convert; 352 /* For color->grayscale conversion, only the Y (0) component is needed */ 353 for (ci = 1; ci < cinfo->num_components; ci++) 354 cinfo->comp_info[ci].component_needed = FALSE; 355 } else 356 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); 357 break; 358 359 case JCS_RGB: 360 cinfo->out_color_components = RGB_PIXELSIZE; 361 if (cinfo->jpeg_color_space == JCS_YCbCr) { 362 cconvert->pub.color_convert = ycc_rgb_convert; 363 build_ycc_rgb_table(cinfo); 364 } else if (cinfo->jpeg_color_space == JCS_GRAYSCALE) { 365 cconvert->pub.color_convert = gray_rgb_convert; 366 } else if (cinfo->jpeg_color_space == JCS_RGB && RGB_PIXELSIZE == 3) { 367 cconvert->pub.color_convert = null_convert; 368 } else 369 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); 370 break; 371 372 case JCS_CMYK: 373 cinfo->out_color_components = 4; 374 if (cinfo->jpeg_color_space == JCS_YCCK) { 375 cconvert->pub.color_convert = ycck_cmyk_convert; 376 build_ycc_rgb_table(cinfo); 377 } else if (cinfo->jpeg_color_space == JCS_CMYK) { 378 cconvert->pub.color_convert = null_convert; 379 } else 380 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); 381 break; 382 383 default: 384 /* Permit null conversion to same output space */ 385 if (cinfo->out_color_space == cinfo->jpeg_color_space) { 386 cinfo->out_color_components = cinfo->num_components; 387 cconvert->pub.color_convert = null_convert; 388 } else /* unsupported non-null conversion */ 389 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); 390 break; 391 } 392 393 if (cinfo->quantize_colors) 394 cinfo->output_components = 1; /* single colormapped output component */ 395 else 396 cinfo->output_components = cinfo->out_color_components; 397 } 398 399 #endif //_FX_JPEG_TURBO_ 400
