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