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| 1 /* |
| 2 * jquant1.c |
| 3 * |
| 4 * Copyright (C) 1991-1996, Thomas G. Lane. |
| 5 * Copyright (C) 2009, D. R. Commander |
| 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 1-pass color quantization (color mapping) routines. |
| 10 * These routines provide mapping to a fixed color map using equally spaced |
| 11 * color values. Optional Floyd-Steinberg or ordered dithering is available. |
| 12 */ |
| 13 |
| 14 #define JPEG_INTERNALS |
| 15 #include "jinclude.h" |
| 16 #include "jpeglib.h" |
| 17 |
| 18 #ifdef QUANT_1PASS_SUPPORTED |
| 19 |
| 20 |
| 21 /* |
| 22 * The main purpose of 1-pass quantization is to provide a fast, if not very |
| 23 * high quality, colormapped output capability. A 2-pass quantizer usually |
| 24 * gives better visual quality; however, for quantized grayscale output this |
| 25 * quantizer is perfectly adequate. Dithering is highly recommended with this |
| 26 * quantizer, though you can turn it off if you really want to. |
| 27 * |
| 28 * In 1-pass quantization the colormap must be chosen in advance of seeing the |
| 29 * image. We use a map consisting of all combinations of Ncolors[i] color |
| 30 * values for the i'th component. The Ncolors[] values are chosen so that |
| 31 * their product, the total number of colors, is no more than that requested. |
| 32 * (In most cases, the product will be somewhat less.) |
| 33 * |
| 34 * Since the colormap is orthogonal, the representative value for each color |
| 35 * component can be determined without considering the other components; |
| 36 * then these indexes can be combined into a colormap index by a standard |
| 37 * N-dimensional-array-subscript calculation. Most of the arithmetic involved |
| 38 * can be precalculated and stored in the lookup table colorindex[]. |
| 39 * colorindex[i][j] maps pixel value j in component i to the nearest |
| 40 * representative value (grid plane) for that component; this index is |
| 41 * multiplied by the array stride for component i, so that the |
| 42 * index of the colormap entry closest to a given pixel value is just |
| 43 * sum( colorindex[component-number][pixel-component-value] ) |
| 44 * Aside from being fast, this scheme allows for variable spacing between |
| 45 * representative values with no additional lookup cost. |
| 46 * |
| 47 * If gamma correction has been applied in color conversion, it might be wise |
| 48 * to adjust the color grid spacing so that the representative colors are |
| 49 * equidistant in linear space. At this writing, gamma correction is not |
| 50 * implemented by jdcolor, so nothing is done here. |
| 51 */ |
| 52 |
| 53 |
| 54 /* Declarations for ordered dithering. |
| 55 * |
| 56 * We use a standard 16x16 ordered dither array. The basic concept of ordered |
| 57 * dithering is described in many references, for instance Dale Schumacher's |
| 58 * chapter II.2 of Graphics Gems II (James Arvo, ed. Academic Press, 1991). |
| 59 * In place of Schumacher's comparisons against a "threshold" value, we add a |
| 60 * "dither" value to the input pixel and then round the result to the nearest |
| 61 * output value. The dither value is equivalent to (0.5 - threshold) times |
| 62 * the distance between output values. For ordered dithering, we assume that |
| 63 * the output colors are equally spaced; if not, results will probably be |
| 64 * worse, since the dither may be too much or too little at a given point. |
| 65 * |
| 66 * The normal calculation would be to form pixel value + dither, range-limit |
| 67 * this to 0..MAXJSAMPLE, and then index into the colorindex table as usual. |
| 68 * We can skip the separate range-limiting step by extending the colorindex |
| 69 * table in both directions. |
| 70 */ |
| 71 |
| 72 #define ODITHER_SIZE 16 /* dimension of dither matrix */ |
| 73 /* NB: if ODITHER_SIZE is not a power of 2, ODITHER_MASK uses will break */ |
| 74 #define ODITHER_CELLS (ODITHER_SIZE*ODITHER_SIZE) /* # cells in matrix */ |
| 75 #define ODITHER_MASK (ODITHER_SIZE-1) /* mask for wrapping around counters */ |
| 76 |
| 77 typedef int ODITHER_MATRIX[ODITHER_SIZE][ODITHER_SIZE]; |
| 78 typedef int (*ODITHER_MATRIX_PTR)[ODITHER_SIZE]; |
| 79 |
| 80 static const UINT8 base_dither_matrix[ODITHER_SIZE][ODITHER_SIZE] = { |
| 81 /* Bayer's order-4 dither array. Generated by the code given in |
| 82 * Stephen Hawley's article "Ordered Dithering" in Graphics Gems I. |
| 83 * The values in this array must range from 0 to ODITHER_CELLS-1. |
| 84 */ |
| 85 { 0,192, 48,240, 12,204, 60,252, 3,195, 51,243, 15,207, 63,255 }, |
| 86 { 128, 64,176,112,140, 76,188,124,131, 67,179,115,143, 79,191,127 }, |
| 87 { 32,224, 16,208, 44,236, 28,220, 35,227, 19,211, 47,239, 31,223 }, |
| 88 { 160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95 }, |
| 89 { 8,200, 56,248, 4,196, 52,244, 11,203, 59,251, 7,199, 55,247 }, |
| 90 { 136, 72,184,120,132, 68,180,116,139, 75,187,123,135, 71,183,119 }, |
| 91 { 40,232, 24,216, 36,228, 20,212, 43,235, 27,219, 39,231, 23,215 }, |
| 92 { 168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87 }, |
| 93 { 2,194, 50,242, 14,206, 62,254, 1,193, 49,241, 13,205, 61,253 }, |
| 94 { 130, 66,178,114,142, 78,190,126,129, 65,177,113,141, 77,189,125 }, |
| 95 { 34,226, 18,210, 46,238, 30,222, 33,225, 17,209, 45,237, 29,221 }, |
| 96 { 162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93 }, |
| 97 { 10,202, 58,250, 6,198, 54,246, 9,201, 57,249, 5,197, 53,245 }, |
| 98 { 138, 74,186,122,134, 70,182,118,137, 73,185,121,133, 69,181,117 }, |
| 99 { 42,234, 26,218, 38,230, 22,214, 41,233, 25,217, 37,229, 21,213 }, |
| 100 { 170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85 } |
| 101 }; |
| 102 |
| 103 |
| 104 /* Declarations for Floyd-Steinberg dithering. |
| 105 * |
| 106 * Errors are accumulated into the array fserrors[], at a resolution of |
| 107 * 1/16th of a pixel count. The error at a given pixel is propagated |
| 108 * to its not-yet-processed neighbors using the standard F-S fractions, |
| 109 * ... (here) 7/16 |
| 110 * 3/16 5/16 1/16 |
| 111 * We work left-to-right on even rows, right-to-left on odd rows. |
| 112 * |
| 113 * We can get away with a single array (holding one row's worth of errors) |
| 114 * by using it to store the current row's errors at pixel columns not yet |
| 115 * processed, but the next row's errors at columns already processed. We |
| 116 * need only a few extra variables to hold the errors immediately around the |
| 117 * current column. (If we are lucky, those variables are in registers, but |
| 118 * even if not, they're probably cheaper to access than array elements are.) |
| 119 * |
| 120 * The fserrors[] array is indexed [component#][position]. |
| 121 * We provide (#columns + 2) entries per component; the extra entry at each |
| 122 * end saves us from special-casing the first and last pixels. |
| 123 * |
| 124 * Note: on a wide image, we might not have enough room in a PC's near data |
| 125 * segment to hold the error array; so it is allocated with alloc_large. |
| 126 */ |
| 127 |
| 128 #if BITS_IN_JSAMPLE == 8 |
| 129 typedef INT16 FSERROR; /* 16 bits should be enough */ |
| 130 typedef int LOCFSERROR; /* use 'int' for calculation temps */ |
| 131 #else |
| 132 typedef INT32 FSERROR; /* may need more than 16 bits */ |
| 133 typedef INT32 LOCFSERROR; /* be sure calculation temps are big enough */ |
| 134 #endif |
| 135 |
| 136 typedef FSERROR FAR *FSERRPTR; /* pointer to error array (in FAR storage!) */ |
| 137 |
| 138 |
| 139 /* Private subobject */ |
| 140 |
| 141 #define MAX_Q_COMPS 4 /* max components I can handle */ |
| 142 |
| 143 typedef struct { |
| 144 struct jpeg_color_quantizer pub; /* public fields */ |
| 145 |
| 146 /* Initially allocated colormap is saved here */ |
| 147 JSAMPARRAY sv_colormap; /* The color map as a 2-D pixel array */ |
| 148 int sv_actual; /* number of entries in use */ |
| 149 |
| 150 JSAMPARRAY colorindex; /* Precomputed mapping for speed */ |
| 151 /* colorindex[i][j] = index of color closest to pixel value j in component i, |
| 152 * premultiplied as described above. Since colormap indexes must fit into |
| 153 * JSAMPLEs, the entries of this array will too. |
| 154 */ |
| 155 boolean is_padded; /* is the colorindex padded for odither? */ |
| 156 |
| 157 int Ncolors[MAX_Q_COMPS]; /* # of values alloced to each component */ |
| 158 |
| 159 /* Variables for ordered dithering */ |
| 160 int row_index; /* cur row's vertical index in dither matrix */ |
| 161 ODITHER_MATRIX_PTR odither[MAX_Q_COMPS]; /* one dither array per component */ |
| 162 |
| 163 /* Variables for Floyd-Steinberg dithering */ |
| 164 FSERRPTR fserrors[MAX_Q_COMPS]; /* accumulated errors */ |
| 165 boolean on_odd_row; /* flag to remember which row we are on */ |
| 166 } my_cquantizer; |
| 167 |
| 168 typedef my_cquantizer * my_cquantize_ptr; |
| 169 |
| 170 |
| 171 /* |
| 172 * Policy-making subroutines for create_colormap and create_colorindex. |
| 173 * These routines determine the colormap to be used. The rest of the module |
| 174 * only assumes that the colormap is orthogonal. |
| 175 * |
| 176 * * select_ncolors decides how to divvy up the available colors |
| 177 * among the components. |
| 178 * * output_value defines the set of representative values for a component. |
| 179 * * largest_input_value defines the mapping from input values to |
| 180 * representative values for a component. |
| 181 * Note that the latter two routines may impose different policies for |
| 182 * different components, though this is not currently done. |
| 183 */ |
| 184 |
| 185 |
| 186 LOCAL(int) |
| 187 select_ncolors (j_decompress_ptr cinfo, int Ncolors[]) |
| 188 /* Determine allocation of desired colors to components, */ |
| 189 /* and fill in Ncolors[] array to indicate choice. */ |
| 190 /* Return value is total number of colors (product of Ncolors[] values). */ |
| 191 { |
| 192 int nc = cinfo->out_color_components; /* number of color components */ |
| 193 int max_colors = cinfo->desired_number_of_colors; |
| 194 int total_colors, iroot, i, j; |
| 195 boolean changed; |
| 196 long temp; |
| 197 int RGB_order[3] = { RGB_GREEN, RGB_RED, RGB_BLUE }; |
| 198 RGB_order[0] = rgb_green[cinfo->out_color_space]; |
| 199 RGB_order[1] = rgb_red[cinfo->out_color_space]; |
| 200 RGB_order[2] = rgb_blue[cinfo->out_color_space]; |
| 201 |
| 202 /* We can allocate at least the nc'th root of max_colors per component. */ |
| 203 /* Compute floor(nc'th root of max_colors). */ |
| 204 iroot = 1; |
| 205 do { |
| 206 iroot++; |
| 207 temp = iroot; /* set temp = iroot ** nc */ |
| 208 for (i = 1; i < nc; i++) |
| 209 temp *= iroot; |
| 210 } while (temp <= (long) max_colors); /* repeat till iroot exceeds root */ |
| 211 iroot--; /* now iroot = floor(root) */ |
| 212 |
| 213 /* Must have at least 2 color values per component */ |
| 214 if (iroot < 2) |
| 215 ERREXIT1(cinfo, JERR_QUANT_FEW_COLORS, (int) temp); |
| 216 |
| 217 /* Initialize to iroot color values for each component */ |
| 218 total_colors = 1; |
| 219 for (i = 0; i < nc; i++) { |
| 220 Ncolors[i] = iroot; |
| 221 total_colors *= iroot; |
| 222 } |
| 223 /* We may be able to increment the count for one or more components without |
| 224 * exceeding max_colors, though we know not all can be incremented. |
| 225 * Sometimes, the first component can be incremented more than once! |
| 226 * (Example: for 16 colors, we start at 2*2*2, go to 3*2*2, then 4*2*2.) |
| 227 * In RGB colorspace, try to increment G first, then R, then B. |
| 228 */ |
| 229 do { |
| 230 changed = FALSE; |
| 231 for (i = 0; i < nc; i++) { |
| 232 j = (cinfo->out_color_space == JCS_RGB ? RGB_order[i] : i); |
| 233 /* calculate new total_colors if Ncolors[j] is incremented */ |
| 234 temp = total_colors / Ncolors[j]; |
| 235 temp *= Ncolors[j]+1; /* done in long arith to avoid oflo */ |
| 236 if (temp > (long) max_colors) |
| 237 break; /* won't fit, done with this pass */ |
| 238 Ncolors[j]++; /* OK, apply the increment */ |
| 239 total_colors = (int) temp; |
| 240 changed = TRUE; |
| 241 } |
| 242 } while (changed); |
| 243 |
| 244 return total_colors; |
| 245 } |
| 246 |
| 247 |
| 248 LOCAL(int) |
| 249 output_value (j_decompress_ptr cinfo, int ci, int j, int maxj) |
| 250 /* Return j'th output value, where j will range from 0 to maxj */ |
| 251 /* The output values must fall in 0..MAXJSAMPLE in increasing order */ |
| 252 { |
| 253 /* We always provide values 0 and MAXJSAMPLE for each component; |
| 254 * any additional values are equally spaced between these limits. |
| 255 * (Forcing the upper and lower values to the limits ensures that |
| 256 * dithering can't produce a color outside the selected gamut.) |
| 257 */ |
| 258 return (int) (((INT32) j * MAXJSAMPLE + maxj/2) / maxj); |
| 259 } |
| 260 |
| 261 |
| 262 LOCAL(int) |
| 263 largest_input_value (j_decompress_ptr cinfo, int ci, int j, int maxj) |
| 264 /* Return largest input value that should map to j'th output value */ |
| 265 /* Must have largest(j=0) >= 0, and largest(j=maxj) >= MAXJSAMPLE */ |
| 266 { |
| 267 /* Breakpoints are halfway between values returned by output_value */ |
| 268 return (int) (((INT32) (2*j + 1) * MAXJSAMPLE + maxj) / (2*maxj)); |
| 269 } |
| 270 |
| 271 |
| 272 /* |
| 273 * Create the colormap. |
| 274 */ |
| 275 |
| 276 LOCAL(void) |
| 277 create_colormap (j_decompress_ptr cinfo) |
| 278 { |
| 279 my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; |
| 280 JSAMPARRAY colormap; /* Created colormap */ |
| 281 int total_colors; /* Number of distinct output colors */ |
| 282 int i,j,k, nci, blksize, blkdist, ptr, val; |
| 283 |
| 284 /* Select number of colors for each component */ |
| 285 total_colors = select_ncolors(cinfo, cquantize->Ncolors); |
| 286 |
| 287 /* Report selected color counts */ |
| 288 if (cinfo->out_color_components == 3) |
| 289 TRACEMS4(cinfo, 1, JTRC_QUANT_3_NCOLORS, |
| 290 total_colors, cquantize->Ncolors[0], |
| 291 cquantize->Ncolors[1], cquantize->Ncolors[2]); |
| 292 else |
| 293 TRACEMS1(cinfo, 1, JTRC_QUANT_NCOLORS, total_colors); |
| 294 |
| 295 /* Allocate and fill in the colormap. */ |
| 296 /* The colors are ordered in the map in standard row-major order, */ |
| 297 /* i.e. rightmost (highest-indexed) color changes most rapidly. */ |
| 298 |
| 299 colormap = (*cinfo->mem->alloc_sarray) |
| 300 ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 301 (JDIMENSION) total_colors, (JDIMENSION) cinfo->out_color_components); |
| 302 |
| 303 /* blksize is number of adjacent repeated entries for a component */ |
| 304 /* blkdist is distance between groups of identical entries for a component */ |
| 305 blkdist = total_colors; |
| 306 |
| 307 for (i = 0; i < cinfo->out_color_components; i++) { |
| 308 /* fill in colormap entries for i'th color component */ |
| 309 nci = cquantize->Ncolors[i]; /* # of distinct values for this color */ |
| 310 blksize = blkdist / nci; |
| 311 for (j = 0; j < nci; j++) { |
| 312 /* Compute j'th output value (out of nci) for component */ |
| 313 val = output_value(cinfo, i, j, nci-1); |
| 314 /* Fill in all colormap entries that have this value of this component */ |
| 315 for (ptr = j * blksize; ptr < total_colors; ptr += blkdist) { |
| 316 /* fill in blksize entries beginning at ptr */ |
| 317 for (k = 0; k < blksize; k++) |
| 318 colormap[i][ptr+k] = (JSAMPLE) val; |
| 319 } |
| 320 } |
| 321 blkdist = blksize; /* blksize of this color is blkdist of next */ |
| 322 } |
| 323 |
| 324 /* Save the colormap in private storage, |
| 325 * where it will survive color quantization mode changes. |
| 326 */ |
| 327 cquantize->sv_colormap = colormap; |
| 328 cquantize->sv_actual = total_colors; |
| 329 } |
| 330 |
| 331 |
| 332 /* |
| 333 * Create the color index table. |
| 334 */ |
| 335 |
| 336 LOCAL(void) |
| 337 create_colorindex (j_decompress_ptr cinfo) |
| 338 { |
| 339 my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; |
| 340 JSAMPROW indexptr; |
| 341 int i,j,k, nci, blksize, val, pad; |
| 342 |
| 343 /* For ordered dither, we pad the color index tables by MAXJSAMPLE in |
| 344 * each direction (input index values can be -MAXJSAMPLE .. 2*MAXJSAMPLE). |
| 345 * This is not necessary in the other dithering modes. However, we |
| 346 * flag whether it was done in case user changes dithering mode. |
| 347 */ |
| 348 if (cinfo->dither_mode == JDITHER_ORDERED) { |
| 349 pad = MAXJSAMPLE*2; |
| 350 cquantize->is_padded = TRUE; |
| 351 } else { |
| 352 pad = 0; |
| 353 cquantize->is_padded = FALSE; |
| 354 } |
| 355 |
| 356 cquantize->colorindex = (*cinfo->mem->alloc_sarray) |
| 357 ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 358 (JDIMENSION) (MAXJSAMPLE+1 + pad), |
| 359 (JDIMENSION) cinfo->out_color_components); |
| 360 |
| 361 /* blksize is number of adjacent repeated entries for a component */ |
| 362 blksize = cquantize->sv_actual; |
| 363 |
| 364 for (i = 0; i < cinfo->out_color_components; i++) { |
| 365 /* fill in colorindex entries for i'th color component */ |
| 366 nci = cquantize->Ncolors[i]; /* # of distinct values for this color */ |
| 367 blksize = blksize / nci; |
| 368 |
| 369 /* adjust colorindex pointers to provide padding at negative indexes. */ |
| 370 if (pad) |
| 371 cquantize->colorindex[i] += MAXJSAMPLE; |
| 372 |
| 373 /* in loop, val = index of current output value, */ |
| 374 /* and k = largest j that maps to current val */ |
| 375 indexptr = cquantize->colorindex[i]; |
| 376 val = 0; |
| 377 k = largest_input_value(cinfo, i, 0, nci-1); |
| 378 for (j = 0; j <= MAXJSAMPLE; j++) { |
| 379 while (j > k) /* advance val if past boundary */ |
| 380 k = largest_input_value(cinfo, i, ++val, nci-1); |
| 381 /* premultiply so that no multiplication needed in main processing */ |
| 382 indexptr[j] = (JSAMPLE) (val * blksize); |
| 383 } |
| 384 /* Pad at both ends if necessary */ |
| 385 if (pad) |
| 386 for (j = 1; j <= MAXJSAMPLE; j++) { |
| 387 indexptr[-j] = indexptr[0]; |
| 388 indexptr[MAXJSAMPLE+j] = indexptr[MAXJSAMPLE]; |
| 389 } |
| 390 } |
| 391 } |
| 392 |
| 393 |
| 394 /* |
| 395 * Create an ordered-dither array for a component having ncolors |
| 396 * distinct output values. |
| 397 */ |
| 398 |
| 399 LOCAL(ODITHER_MATRIX_PTR) |
| 400 make_odither_array (j_decompress_ptr cinfo, int ncolors) |
| 401 { |
| 402 ODITHER_MATRIX_PTR odither; |
| 403 int j,k; |
| 404 INT32 num,den; |
| 405 |
| 406 odither = (ODITHER_MATRIX_PTR) |
| 407 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 408 SIZEOF(ODITHER_MATRIX)); |
| 409 /* The inter-value distance for this color is MAXJSAMPLE/(ncolors-1). |
| 410 * Hence the dither value for the matrix cell with fill order f |
| 411 * (f=0..N-1) should be (N-1-2*f)/(2*N) * MAXJSAMPLE/(ncolors-1). |
| 412 * On 16-bit-int machine, be careful to avoid overflow. |
| 413 */ |
| 414 den = 2 * ODITHER_CELLS * ((INT32) (ncolors - 1)); |
| 415 for (j = 0; j < ODITHER_SIZE; j++) { |
| 416 for (k = 0; k < ODITHER_SIZE; k++) { |
| 417 num = ((INT32) (ODITHER_CELLS-1 - 2*((int)base_dither_matrix[j][k]))) |
| 418 * MAXJSAMPLE; |
| 419 /* Ensure round towards zero despite C's lack of consistency |
| 420 * about rounding negative values in integer division... |
| 421 */ |
| 422 odither[j][k] = (int) (num<0 ? -((-num)/den) : num/den); |
| 423 } |
| 424 } |
| 425 return odither; |
| 426 } |
| 427 |
| 428 |
| 429 /* |
| 430 * Create the ordered-dither tables. |
| 431 * Components having the same number of representative colors may |
| 432 * share a dither table. |
| 433 */ |
| 434 |
| 435 LOCAL(void) |
| 436 create_odither_tables (j_decompress_ptr cinfo) |
| 437 { |
| 438 my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; |
| 439 ODITHER_MATRIX_PTR odither; |
| 440 int i, j, nci; |
| 441 |
| 442 for (i = 0; i < cinfo->out_color_components; i++) { |
| 443 nci = cquantize->Ncolors[i]; /* # of distinct values for this color */ |
| 444 odither = NULL; /* search for matching prior component */ |
| 445 for (j = 0; j < i; j++) { |
| 446 if (nci == cquantize->Ncolors[j]) { |
| 447 odither = cquantize->odither[j]; |
| 448 break; |
| 449 } |
| 450 } |
| 451 if (odither == NULL) /* need a new table? */ |
| 452 odither = make_odither_array(cinfo, nci); |
| 453 cquantize->odither[i] = odither; |
| 454 } |
| 455 } |
| 456 |
| 457 |
| 458 /* |
| 459 * Map some rows of pixels to the output colormapped representation. |
| 460 */ |
| 461 |
| 462 METHODDEF(void) |
| 463 color_quantize (j_decompress_ptr cinfo, JSAMPARRAY input_buf, |
| 464 JSAMPARRAY output_buf, int num_rows) |
| 465 /* General case, no dithering */ |
| 466 { |
| 467 my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; |
| 468 JSAMPARRAY colorindex = cquantize->colorindex; |
| 469 register int pixcode, ci; |
| 470 register JSAMPROW ptrin, ptrout; |
| 471 int row; |
| 472 JDIMENSION col; |
| 473 JDIMENSION width = cinfo->output_width; |
| 474 register int nc = cinfo->out_color_components; |
| 475 |
| 476 for (row = 0; row < num_rows; row++) { |
| 477 ptrin = input_buf[row]; |
| 478 ptrout = output_buf[row]; |
| 479 for (col = width; col > 0; col--) { |
| 480 pixcode = 0; |
| 481 for (ci = 0; ci < nc; ci++) { |
| 482 pixcode += GETJSAMPLE(colorindex[ci][GETJSAMPLE(*ptrin++)]); |
| 483 } |
| 484 *ptrout++ = (JSAMPLE) pixcode; |
| 485 } |
| 486 } |
| 487 } |
| 488 |
| 489 |
| 490 METHODDEF(void) |
| 491 color_quantize3 (j_decompress_ptr cinfo, JSAMPARRAY input_buf, |
| 492 JSAMPARRAY output_buf, int num_rows) |
| 493 /* Fast path for out_color_components==3, no dithering */ |
| 494 { |
| 495 my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; |
| 496 register int pixcode; |
| 497 register JSAMPROW ptrin, ptrout; |
| 498 JSAMPROW colorindex0 = cquantize->colorindex[0]; |
| 499 JSAMPROW colorindex1 = cquantize->colorindex[1]; |
| 500 JSAMPROW colorindex2 = cquantize->colorindex[2]; |
| 501 int row; |
| 502 JDIMENSION col; |
| 503 JDIMENSION width = cinfo->output_width; |
| 504 |
| 505 for (row = 0; row < num_rows; row++) { |
| 506 ptrin = input_buf[row]; |
| 507 ptrout = output_buf[row]; |
| 508 for (col = width; col > 0; col--) { |
| 509 pixcode = GETJSAMPLE(colorindex0[GETJSAMPLE(*ptrin++)]); |
| 510 pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*ptrin++)]); |
| 511 pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*ptrin++)]); |
| 512 *ptrout++ = (JSAMPLE) pixcode; |
| 513 } |
| 514 } |
| 515 } |
| 516 |
| 517 |
| 518 METHODDEF(void) |
| 519 quantize_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf, |
| 520 JSAMPARRAY output_buf, int num_rows) |
| 521 /* General case, with ordered dithering */ |
| 522 { |
| 523 my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; |
| 524 register JSAMPROW input_ptr; |
| 525 register JSAMPROW output_ptr; |
| 526 JSAMPROW colorindex_ci; |
| 527 int * dither; /* points to active row of dither matrix */ |
| 528 int row_index, col_index; /* current indexes into dither matrix */ |
| 529 int nc = cinfo->out_color_components; |
| 530 int ci; |
| 531 int row; |
| 532 JDIMENSION col; |
| 533 JDIMENSION width = cinfo->output_width; |
| 534 |
| 535 for (row = 0; row < num_rows; row++) { |
| 536 /* Initialize output values to 0 so can process components separately */ |
| 537 jzero_far((void FAR *) output_buf[row], |
| 538 (size_t) (width * SIZEOF(JSAMPLE))); |
| 539 row_index = cquantize->row_index; |
| 540 for (ci = 0; ci < nc; ci++) { |
| 541 input_ptr = input_buf[row] + ci; |
| 542 output_ptr = output_buf[row]; |
| 543 colorindex_ci = cquantize->colorindex[ci]; |
| 544 dither = cquantize->odither[ci][row_index]; |
| 545 col_index = 0; |
| 546 |
| 547 for (col = width; col > 0; col--) { |
| 548 /* Form pixel value + dither, range-limit to 0..MAXJSAMPLE, |
| 549 * select output value, accumulate into output code for this pixel. |
| 550 * Range-limiting need not be done explicitly, as we have extended |
| 551 * the colorindex table to produce the right answers for out-of-range |
| 552 * inputs. The maximum dither is +- MAXJSAMPLE; this sets the |
| 553 * required amount of padding. |
| 554 */ |
| 555 *output_ptr += colorindex_ci[GETJSAMPLE(*input_ptr)+dither[col_index]]; |
| 556 input_ptr += nc; |
| 557 output_ptr++; |
| 558 col_index = (col_index + 1) & ODITHER_MASK; |
| 559 } |
| 560 } |
| 561 /* Advance row index for next row */ |
| 562 row_index = (row_index + 1) & ODITHER_MASK; |
| 563 cquantize->row_index = row_index; |
| 564 } |
| 565 } |
| 566 |
| 567 |
| 568 METHODDEF(void) |
| 569 quantize3_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf, |
| 570 JSAMPARRAY output_buf, int num_rows) |
| 571 /* Fast path for out_color_components==3, with ordered dithering */ |
| 572 { |
| 573 my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; |
| 574 register int pixcode; |
| 575 register JSAMPROW input_ptr; |
| 576 register JSAMPROW output_ptr; |
| 577 JSAMPROW colorindex0 = cquantize->colorindex[0]; |
| 578 JSAMPROW colorindex1 = cquantize->colorindex[1]; |
| 579 JSAMPROW colorindex2 = cquantize->colorindex[2]; |
| 580 int * dither0; /* points to active row of dither matrix */ |
| 581 int * dither1; |
| 582 int * dither2; |
| 583 int row_index, col_index; /* current indexes into dither matrix */ |
| 584 int row; |
| 585 JDIMENSION col; |
| 586 JDIMENSION width = cinfo->output_width; |
| 587 |
| 588 for (row = 0; row < num_rows; row++) { |
| 589 row_index = cquantize->row_index; |
| 590 input_ptr = input_buf[row]; |
| 591 output_ptr = output_buf[row]; |
| 592 dither0 = cquantize->odither[0][row_index]; |
| 593 dither1 = cquantize->odither[1][row_index]; |
| 594 dither2 = cquantize->odither[2][row_index]; |
| 595 col_index = 0; |
| 596 |
| 597 for (col = width; col > 0; col--) { |
| 598 pixcode = GETJSAMPLE(colorindex0[GETJSAMPLE(*input_ptr++) + |
| 599 dither0[col_index]]); |
| 600 pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*input_ptr++) + |
| 601 dither1[col_index]]); |
| 602 pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*input_ptr++) + |
| 603 dither2[col_index]]); |
| 604 *output_ptr++ = (JSAMPLE) pixcode; |
| 605 col_index = (col_index + 1) & ODITHER_MASK; |
| 606 } |
| 607 row_index = (row_index + 1) & ODITHER_MASK; |
| 608 cquantize->row_index = row_index; |
| 609 } |
| 610 } |
| 611 |
| 612 |
| 613 METHODDEF(void) |
| 614 quantize_fs_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf, |
| 615 JSAMPARRAY output_buf, int num_rows) |
| 616 /* General case, with Floyd-Steinberg dithering */ |
| 617 { |
| 618 my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; |
| 619 register LOCFSERROR cur; /* current error or pixel value */ |
| 620 LOCFSERROR belowerr; /* error for pixel below cur */ |
| 621 LOCFSERROR bpreverr; /* error for below/prev col */ |
| 622 LOCFSERROR bnexterr; /* error for below/next col */ |
| 623 LOCFSERROR delta; |
| 624 register FSERRPTR errorptr; /* => fserrors[] at column before current */ |
| 625 register JSAMPROW input_ptr; |
| 626 register JSAMPROW output_ptr; |
| 627 JSAMPROW colorindex_ci; |
| 628 JSAMPROW colormap_ci; |
| 629 int pixcode; |
| 630 int nc = cinfo->out_color_components; |
| 631 int dir; /* 1 for left-to-right, -1 for right-to-left */ |
| 632 int dirnc; /* dir * nc */ |
| 633 int ci; |
| 634 int row; |
| 635 JDIMENSION col; |
| 636 JDIMENSION width = cinfo->output_width; |
| 637 JSAMPLE *range_limit = cinfo->sample_range_limit; |
| 638 SHIFT_TEMPS |
| 639 |
| 640 for (row = 0; row < num_rows; row++) { |
| 641 /* Initialize output values to 0 so can process components separately */ |
| 642 jzero_far((void FAR *) output_buf[row], |
| 643 (size_t) (width * SIZEOF(JSAMPLE))); |
| 644 for (ci = 0; ci < nc; ci++) { |
| 645 input_ptr = input_buf[row] + ci; |
| 646 output_ptr = output_buf[row]; |
| 647 if (cquantize->on_odd_row) { |
| 648 /* work right to left in this row */ |
| 649 input_ptr += (width-1) * nc; /* so point to rightmost pixel */ |
| 650 output_ptr += width-1; |
| 651 dir = -1; |
| 652 dirnc = -nc; |
| 653 errorptr = cquantize->fserrors[ci] + (width+1); /* => entry after last c
olumn */ |
| 654 } else { |
| 655 /* work left to right in this row */ |
| 656 dir = 1; |
| 657 dirnc = nc; |
| 658 errorptr = cquantize->fserrors[ci]; /* => entry before first column */ |
| 659 } |
| 660 colorindex_ci = cquantize->colorindex[ci]; |
| 661 colormap_ci = cquantize->sv_colormap[ci]; |
| 662 /* Preset error values: no error propagated to first pixel from left */ |
| 663 cur = 0; |
| 664 /* and no error propagated to row below yet */ |
| 665 belowerr = bpreverr = 0; |
| 666 |
| 667 for (col = width; col > 0; col--) { |
| 668 /* cur holds the error propagated from the previous pixel on the |
| 669 * current line. Add the error propagated from the previous line |
| 670 * to form the complete error correction term for this pixel, and |
| 671 * round the error term (which is expressed * 16) to an integer. |
| 672 * RIGHT_SHIFT rounds towards minus infinity, so adding 8 is correct |
| 673 * for either sign of the error value. |
| 674 * Note: errorptr points to *previous* column's array entry. |
| 675 */ |
| 676 cur = RIGHT_SHIFT(cur + errorptr[dir] + 8, 4); |
| 677 /* Form pixel value + error, and range-limit to 0..MAXJSAMPLE. |
| 678 * The maximum error is +- MAXJSAMPLE; this sets the required size |
| 679 * of the range_limit array. |
| 680 */ |
| 681 cur += GETJSAMPLE(*input_ptr); |
| 682 cur = GETJSAMPLE(range_limit[cur]); |
| 683 /* Select output value, accumulate into output code for this pixel */ |
| 684 pixcode = GETJSAMPLE(colorindex_ci[cur]); |
| 685 *output_ptr += (JSAMPLE) pixcode; |
| 686 /* Compute actual representation error at this pixel */ |
| 687 /* Note: we can do this even though we don't have the final */ |
| 688 /* pixel code, because the colormap is orthogonal. */ |
| 689 cur -= GETJSAMPLE(colormap_ci[pixcode]); |
| 690 /* Compute error fractions to be propagated to adjacent pixels. |
| 691 * Add these into the running sums, and simultaneously shift the |
| 692 * next-line error sums left by 1 column. |
| 693 */ |
| 694 bnexterr = cur; |
| 695 delta = cur * 2; |
| 696 cur += delta; /* form error * 3 */ |
| 697 errorptr[0] = (FSERROR) (bpreverr + cur); |
| 698 cur += delta; /* form error * 5 */ |
| 699 bpreverr = belowerr + cur; |
| 700 belowerr = bnexterr; |
| 701 cur += delta; /* form error * 7 */ |
| 702 /* At this point cur contains the 7/16 error value to be propagated |
| 703 * to the next pixel on the current line, and all the errors for the |
| 704 * next line have been shifted over. We are therefore ready to move on. |
| 705 */ |
| 706 input_ptr += dirnc; /* advance input ptr to next column */ |
| 707 output_ptr += dir; /* advance output ptr to next column */ |
| 708 errorptr += dir; /* advance errorptr to current column */ |
| 709 } |
| 710 /* Post-loop cleanup: we must unload the final error value into the |
| 711 * final fserrors[] entry. Note we need not unload belowerr because |
| 712 * it is for the dummy column before or after the actual array. |
| 713 */ |
| 714 errorptr[0] = (FSERROR) bpreverr; /* unload prev err into array */ |
| 715 } |
| 716 cquantize->on_odd_row = (cquantize->on_odd_row ? FALSE : TRUE); |
| 717 } |
| 718 } |
| 719 |
| 720 |
| 721 /* |
| 722 * Allocate workspace for Floyd-Steinberg errors. |
| 723 */ |
| 724 |
| 725 LOCAL(void) |
| 726 alloc_fs_workspace (j_decompress_ptr cinfo) |
| 727 { |
| 728 my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; |
| 729 size_t arraysize; |
| 730 int i; |
| 731 |
| 732 arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR)); |
| 733 for (i = 0; i < cinfo->out_color_components; i++) { |
| 734 cquantize->fserrors[i] = (FSERRPTR) |
| 735 (*cinfo->mem->alloc_large)((j_common_ptr) cinfo, JPOOL_IMAGE, arraysize); |
| 736 } |
| 737 } |
| 738 |
| 739 |
| 740 /* |
| 741 * Initialize for one-pass color quantization. |
| 742 */ |
| 743 |
| 744 METHODDEF(void) |
| 745 start_pass_1_quant (j_decompress_ptr cinfo, boolean is_pre_scan) |
| 746 { |
| 747 my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; |
| 748 size_t arraysize; |
| 749 int i; |
| 750 |
| 751 /* Install my colormap. */ |
| 752 cinfo->colormap = cquantize->sv_colormap; |
| 753 cinfo->actual_number_of_colors = cquantize->sv_actual; |
| 754 |
| 755 /* Initialize for desired dithering mode. */ |
| 756 switch (cinfo->dither_mode) { |
| 757 case JDITHER_NONE: |
| 758 if (cinfo->out_color_components == 3) |
| 759 cquantize->pub.color_quantize = color_quantize3; |
| 760 else |
| 761 cquantize->pub.color_quantize = color_quantize; |
| 762 break; |
| 763 case JDITHER_ORDERED: |
| 764 if (cinfo->out_color_components == 3) |
| 765 cquantize->pub.color_quantize = quantize3_ord_dither; |
| 766 else |
| 767 cquantize->pub.color_quantize = quantize_ord_dither; |
| 768 cquantize->row_index = 0; /* initialize state for ordered dither */ |
| 769 /* If user changed to ordered dither from another mode, |
| 770 * we must recreate the color index table with padding. |
| 771 * This will cost extra space, but probably isn't very likely. |
| 772 */ |
| 773 if (! cquantize->is_padded) |
| 774 create_colorindex(cinfo); |
| 775 /* Create ordered-dither tables if we didn't already. */ |
| 776 if (cquantize->odither[0] == NULL) |
| 777 create_odither_tables(cinfo); |
| 778 break; |
| 779 case JDITHER_FS: |
| 780 cquantize->pub.color_quantize = quantize_fs_dither; |
| 781 cquantize->on_odd_row = FALSE; /* initialize state for F-S dither */ |
| 782 /* Allocate Floyd-Steinberg workspace if didn't already. */ |
| 783 if (cquantize->fserrors[0] == NULL) |
| 784 alloc_fs_workspace(cinfo); |
| 785 /* Initialize the propagated errors to zero. */ |
| 786 arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR)); |
| 787 for (i = 0; i < cinfo->out_color_components; i++) |
| 788 jzero_far((void FAR *) cquantize->fserrors[i], arraysize); |
| 789 break; |
| 790 default: |
| 791 ERREXIT(cinfo, JERR_NOT_COMPILED); |
| 792 break; |
| 793 } |
| 794 } |
| 795 |
| 796 |
| 797 /* |
| 798 * Finish up at the end of the pass. |
| 799 */ |
| 800 |
| 801 METHODDEF(void) |
| 802 finish_pass_1_quant (j_decompress_ptr cinfo) |
| 803 { |
| 804 /* no work in 1-pass case */ |
| 805 } |
| 806 |
| 807 |
| 808 /* |
| 809 * Switch to a new external colormap between output passes. |
| 810 * Shouldn't get to this module! |
| 811 */ |
| 812 |
| 813 METHODDEF(void) |
| 814 new_color_map_1_quant (j_decompress_ptr cinfo) |
| 815 { |
| 816 ERREXIT(cinfo, JERR_MODE_CHANGE); |
| 817 } |
| 818 |
| 819 |
| 820 /* |
| 821 * Module initialization routine for 1-pass color quantization. |
| 822 */ |
| 823 |
| 824 GLOBAL(void) |
| 825 jinit_1pass_quantizer (j_decompress_ptr cinfo) |
| 826 { |
| 827 my_cquantize_ptr cquantize; |
| 828 |
| 829 cquantize = (my_cquantize_ptr) |
| 830 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 831 SIZEOF(my_cquantizer)); |
| 832 cinfo->cquantize = (struct jpeg_color_quantizer *) cquantize; |
| 833 cquantize->pub.start_pass = start_pass_1_quant; |
| 834 cquantize->pub.finish_pass = finish_pass_1_quant; |
| 835 cquantize->pub.new_color_map = new_color_map_1_quant; |
| 836 cquantize->fserrors[0] = NULL; /* Flag FS workspace not allocated */ |
| 837 cquantize->odither[0] = NULL; /* Also flag odither arrays not allocated */ |
| 838 |
| 839 /* Make sure my internal arrays won't overflow */ |
| 840 if (cinfo->out_color_components > MAX_Q_COMPS) |
| 841 ERREXIT1(cinfo, JERR_QUANT_COMPONENTS, MAX_Q_COMPS); |
| 842 /* Make sure colormap indexes can be represented by JSAMPLEs */ |
| 843 if (cinfo->desired_number_of_colors > (MAXJSAMPLE+1)) |
| 844 ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, MAXJSAMPLE+1); |
| 845 |
| 846 /* Create the colormap and color index table. */ |
| 847 create_colormap(cinfo); |
| 848 create_colorindex(cinfo); |
| 849 |
| 850 /* Allocate Floyd-Steinberg workspace now if requested. |
| 851 * We do this now since it is FAR storage and may affect the memory |
| 852 * manager's space calculations. If the user changes to FS dither |
| 853 * mode in a later pass, we will allocate the space then, and will |
| 854 * possibly overrun the max_memory_to_use setting. |
| 855 */ |
| 856 if (cinfo->dither_mode == JDITHER_FS) |
| 857 alloc_fs_workspace(cinfo); |
| 858 } |
| 859 |
| 860 #endif /* QUANT_1PASS_SUPPORTED */ |
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