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jquant1.cpp
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1 /* +---------------------------------------------------------------------------+
2  | Mobile Robot Programming Toolkit (MRPT) |
3  | http://www.mrpt.org/ |
4  | |
5  | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file |
6  | See: http://www.mrpt.org/Authors - All rights reserved. |
7  | Released under BSD License. See details in http://www.mrpt.org/License |
8  +---------------------------------------------------------------------------+ */
9 
10 #define JPEG_INTERNALS
11 #include "jinclude.h"
12 #include "mrpt_jpeglib.h"
13 #include <mrpt/utils/mrpt_macros.h>
14 
15 #ifdef QUANT_1PASS_SUPPORTED
16 
17 
18 /*
19  * The main purpose of 1-pass quantization is to provide a fast, if not very
20  * high quality, colormapped output capability. A 2-pass quantizer usually
21  * gives better visual quality; however, for quantized grayscale output this
22  * quantizer is perfectly adequate. Dithering is highly recommended with this
23  * quantizer, though you can turn it off if you really want to.
24  *
25  * In 1-pass quantization the colormap must be chosen in advance of seeing the
26  * image. We use a map consisting of all combinations of Ncolors[i] color
27  * values for the i'th component. The Ncolors[] values are chosen so that
28  * their product, the total number of colors, is no more than that requested.
29  * (In most cases, the product will be somewhat less.)
30  *
31  * Since the colormap is orthogonal, the representative value for each color
32  * component can be determined without considering the other components;
33  * then these indexes can be combined into a colormap index by a standard
34  * N-dimensional-array-subscript calculation. Most of the arithmetic involved
35  * can be precalculated and stored in the lookup table colorindex[].
36  * colorindex[i][j] maps pixel value j in component i to the nearest
37  * representative value (grid plane) for that component; this index is
38  * multiplied by the array stride for component i, so that the
39  * index of the colormap entry closest to a given pixel value is just
40  * sum( colorindex[component-number][pixel-component-value] )
41  * Aside from being fast, this scheme allows for variable spacing between
42  * representative values with no additional lookup cost.
43  *
44  * If gamma correction has been applied in color conversion, it might be wise
45  * to adjust the color grid spacing so that the representative colors are
46  * equidistant in linear space. At this writing, gamma correction is not
47  * implemented by jdcolor, so nothing is done here.
48  */
49 
50 
51 /* Declarations for ordered dithering.
52  *
53  * We use a standard 16x16 ordered dither array. The basic concept of ordered
54  * dithering is described in many references, for instance Dale Schumacher's
55  * chapter II.2 of Graphics Gems II (James Arvo, ed. Academic Press, 1991).
56  * In place of Schumacher's comparisons against a "threshold" value, we add a
57  * "dither" value to the input pixel and then round the result to the nearest
58  * output value. The dither value is equivalent to (0.5 - threshold) times
59  * the distance between output values. For ordered dithering, we assume that
60  * the output colors are equally spaced; if not, results will probably be
61  * worse, since the dither may be too much or too little at a given point.
62  *
63  * The normal calculation would be to form pixel value + dither, range-limit
64  * this to 0..MAXJSAMPLE, and then index into the colorindex table as usual.
65  * We can skip the separate range-limiting step by extending the colorindex
66  * table in both directions.
67  */
68 
69 #define ODITHER_SIZE 16 /* dimension of dither matrix */
70 /* NB: if ODITHER_SIZE is not a power of 2, ODITHER_MASK uses will break */
71 #define ODITHER_CELLS (ODITHER_SIZE*ODITHER_SIZE) /* # cells in matrix */
72 #define ODITHER_MASK (ODITHER_SIZE-1) /* mask for wrapping around counters */
73 
76 
78  /* Bayer's order-4 dither array. Generated by the code given in
79  * Stephen Hawley's article "Ordered Dithering" in Graphics Gems I.
80  * The values in this array must range from 0 to ODITHER_CELLS-1.
81  */
82  { 0,192, 48,240, 12,204, 60,252, 3,195, 51,243, 15,207, 63,255 },
83  { 128, 64,176,112,140, 76,188,124,131, 67,179,115,143, 79,191,127 },
84  { 32,224, 16,208, 44,236, 28,220, 35,227, 19,211, 47,239, 31,223 },
85  { 160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95 },
86  { 8,200, 56,248, 4,196, 52,244, 11,203, 59,251, 7,199, 55,247 },
87  { 136, 72,184,120,132, 68,180,116,139, 75,187,123,135, 71,183,119 },
88  { 40,232, 24,216, 36,228, 20,212, 43,235, 27,219, 39,231, 23,215 },
89  { 168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87 },
90  { 2,194, 50,242, 14,206, 62,254, 1,193, 49,241, 13,205, 61,253 },
91  { 130, 66,178,114,142, 78,190,126,129, 65,177,113,141, 77,189,125 },
92  { 34,226, 18,210, 46,238, 30,222, 33,225, 17,209, 45,237, 29,221 },
93  { 162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93 },
94  { 10,202, 58,250, 6,198, 54,246, 9,201, 57,249, 5,197, 53,245 },
95  { 138, 74,186,122,134, 70,182,118,137, 73,185,121,133, 69,181,117 },
96  { 42,234, 26,218, 38,230, 22,214, 41,233, 25,217, 37,229, 21,213 },
97  { 170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85 }
98 };
99 
100 
101 /* Declarations for Floyd-Steinberg dithering.
102  *
103  * Errors are accumulated into the array fserrors[], at a resolution of
104  * 1/16th of a pixel count. The error at a given pixel is propagated
105  * to its not-yet-processed neighbors using the standard F-S fractions,
106  * ... (here) 7/16
107  * 3/16 5/16 1/16
108  * We work left-to-right on even rows, right-to-left on odd rows.
109  *
110  * We can get away with a single array (holding one row's worth of errors)
111  * by using it to store the current row's errors at pixel columns not yet
112  * processed, but the next row's errors at columns already processed. We
113  * need only a few extra variables to hold the errors immediately around the
114  * current column. (If we are lucky, those variables are in registers, but
115  * even if not, they're probably cheaper to access than array elements are.)
116  *
117  * The fserrors[] array is indexed [component#][position].
118  * We provide (#columns + 2) entries per component; the extra entry at each
119  * end saves us from special-casing the first and last pixels.
120  *
121  * Note: on a wide image, we might not have enough room in a PC's near data
122  * segment to hold the error array; so it is allocated with alloc_large.
123  */
124 
125 #if BITS_IN_JSAMPLE == 8
126 typedef INT16 FSERROR; /* 16 bits should be enough */
127 typedef int LOCFSERROR; /* use 'int' for calculation temps */
128 #else
129 typedef INT32 FSERROR; /* may need more than 16 bits */
130 typedef INT32 LOCFSERROR; /* be sure calculation temps are big enough */
131 #endif
132 
133 typedef FSERROR FAR *FSERRPTR; /* pointer to error array (in FAR storage!) */
134 
135 
136 /* Private subobject */
137 
138 #define MAX_Q_COMPS 4 /* max components I can handle */
139 
140 typedef struct {
141  struct jpeg_color_quantizer pub; /* public fields */
142 
143  /* Initially allocated colormap is saved here */
144  JSAMPARRAY sv_colormap; /* The color map as a 2-D pixel array */
145  int sv_actual; /* number of entries in use */
146 
147  JSAMPARRAY colorindex; /* Precomputed mapping for speed */
148  /* colorindex[i][j] = index of color closest to pixel value j in component i,
149  * premultiplied as described above. Since colormap indexes must fit into
150  * JSAMPLEs, the entries of this array will too.
151  */
152  boolean is_padded; /* is the colorindex padded for odither? */
153 
154  int Ncolors[MAX_Q_COMPS]; /* # of values alloced to each component */
155 
156  /* Variables for ordered dithering */
157  int row_index; /* cur row's vertical index in dither matrix */
158  ODITHER_MATRIX_PTR odither[MAX_Q_COMPS]; /* one dither array per component */
159 
160  /* Variables for Floyd-Steinberg dithering */
161  FSERRPTR fserrors[MAX_Q_COMPS]; /* accumulated errors */
162  boolean on_odd_row; /* flag to remember which row we are on */
163 } my_cquantizer;
164 
166 
167 
168 /*
169  * Policy-making subroutines for create_colormap and create_colorindex.
170  * These routines determine the colormap to be used. The rest of the module
171  * only assumes that the colormap is orthogonal.
172  *
173  * * select_ncolors decides how to divvy up the available colors
174  * among the components.
175  * * output_value defines the set of representative values for a component.
176  * * largest_input_value defines the mapping from input values to
177  * representative values for a component.
178  * Note that the latter two routines may impose different policies for
179  * different components, though this is not currently done.
180  */
181 
182 
183 LOCAL(int)
184 select_ncolors (j_decompress_ptr cinfo, int Ncolors[])
185 /* Determine allocation of desired colors to components, */
186 /* and fill in Ncolors[] array to indicate choice. */
187 /* Return value is total number of colors (product of Ncolors[] values). */
188 {
189  int nc = cinfo->out_color_components; /* number of color components */
190  int max_colors = cinfo->desired_number_of_colors;
191  int total_colors, iroot, i, j;
192  boolean changed;
193  long temp;
194  static const int RGB_order[3] = { RGB_GREEN, RGB_RED, RGB_BLUE };
195 
196  /* We can allocate at least the nc'th root of max_colors per component. */
197  /* Compute floor(nc'th root of max_colors). */
198  iroot = 1;
199  do {
200  iroot++;
201  temp = iroot; /* set temp = iroot ** nc */
202  for (i = 1; i < nc; i++)
203  temp *= iroot;
204  } while (temp <= (long) max_colors); /* repeat till iroot exceeds root */
205  iroot--; /* now iroot = floor(root) */
206 
207  /* Must have at least 2 color values per component */
208  if (iroot < 2)
209  ERREXIT1(cinfo, JERR_QUANT_FEW_COLORS, (int) temp);
210 
211  /* Initialize to iroot color values for each component */
212  total_colors = 1;
213  for (i = 0; i < nc; i++) {
214  Ncolors[i] = iroot;
215  total_colors *= iroot;
216  }
217  /* We may be able to increment the count for one or more components without
218  * exceeding max_colors, though we know not all can be incremented.
219  * Sometimes, the first component can be incremented more than once!
220  * (Example: for 16 colors, we start at 2*2*2, go to 3*2*2, then 4*2*2.)
221  * In RGB colorspace, try to increment G first, then R, then B.
222  */
223  do {
224  changed = FALSE;
225  for (i = 0; i < nc; i++) {
226  j = (cinfo->out_color_space == JCS_RGB ? RGB_order[i] : i);
227  /* calculate new total_colors if Ncolors[j] is incremented */
228  temp = total_colors / Ncolors[j];
229  temp *= Ncolors[j]+1; /* done in long arith to avoid oflo */
230  if (temp > (long) max_colors)
231  break; /* won't fit, done with this pass */
232  Ncolors[j]++; /* OK, apply the increment */
233  total_colors = (int) temp;
234  changed = TRUE;
235  }
236  } while (changed);
237 
238  return total_colors;
239 }
240 
241 
242 LOCAL(int)
243 output_value (j_decompress_ptr cinfo, int ci, int j, int maxj)
244 /* Return j'th output value, where j will range from 0 to maxj */
245 /* The output values must fall in 0..MAXJSAMPLE in increasing order */
246 {
248  /* We always provide values 0 and MAXJSAMPLE for each component;
249  * any additional values are equally spaced between these limits.
250  * (Forcing the upper and lower values to the limits ensures that
251  * dithering can't produce a color outside the selected gamut.)
252  */
253  return (int) (((INT32) j * MAXJSAMPLE + maxj/2) / maxj);
254 }
255 
256 
257 LOCAL(int)
258 largest_input_value (j_decompress_ptr cinfo, int ci, int j, int maxj)
259 /* Return largest input value that should map to j'th output value */
260 /* Must have largest(j=0) >= 0, and largest(j=maxj) >= MAXJSAMPLE */
261 {
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)
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)
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 
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,
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)
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)
461 /* General case, no dithering */
462 {
463  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
464  JSAMPARRAY colorindex = cquantize->colorindex;
465  int pixcode, ci;
466  JSAMPROW ptrin, ptrout;
467  int row;
468  JDIMENSION col;
469  JDIMENSION width = cinfo->output_width;
470  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)
489 /* Fast path for out_color_components==3, no dithering */
490 {
491  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
492  int pixcode;
493  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)
517 /* General case, with ordered dithering */
518 {
519  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
520  JSAMPROW input_ptr;
521  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)
567 /* Fast path for out_color_components==3, with ordered dithering */
568 {
569  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
570  int pixcode;
571  JSAMPROW input_ptr;
572  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)
612 /* General case, with Floyd-Steinberg dithering */
613 {
614  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
615  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  FSERRPTR errorptr; /* => fserrors[] at column before current */
621  JSAMPROW input_ptr;
622  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;
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)
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  MRPT_UNUSED_PARAM(is_pre_scan);
744  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
745  size_t arraysize;
746  int i;
747 
748  /* Install my colormap. */
749  cinfo->colormap = cquantize->sv_colormap;
750  cinfo->actual_number_of_colors = cquantize->sv_actual;
751 
752  /* Initialize for desired dithering mode. */
753  switch (cinfo->dither_mode) {
754  case JDITHER_NONE:
755  if (cinfo->out_color_components == 3)
756  cquantize->pub.color_quantize = color_quantize3;
757  else
758  cquantize->pub.color_quantize = color_quantize;
759  break;
760  case JDITHER_ORDERED:
761  if (cinfo->out_color_components == 3)
762  cquantize->pub.color_quantize = quantize3_ord_dither;
763  else
764  cquantize->pub.color_quantize = quantize_ord_dither;
765  cquantize->row_index = 0; /* initialize state for ordered dither */
766  /* If user changed to ordered dither from another mode,
767  * we must recreate the color index table with padding.
768  * This will cost extra space, but probably isn't very likely.
769  */
770  if (! cquantize->is_padded)
771  create_colorindex(cinfo);
772  /* Create ordered-dither tables if we didn't already. */
773  if (cquantize->odither[0] == NULL)
774  create_odither_tables(cinfo);
775  break;
776  case JDITHER_FS:
777  cquantize->pub.color_quantize = quantize_fs_dither;
778  cquantize->on_odd_row = FALSE; /* initialize state for F-S dither */
779  /* Allocate Floyd-Steinberg workspace if didn't already. */
780  if (cquantize->fserrors[0] == NULL)
781  alloc_fs_workspace(cinfo);
782  /* Initialize the propagated errors to zero. */
783  arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR));
784  for (i = 0; i < cinfo->out_color_components; i++)
785  jzero_far((void FAR *) cquantize->fserrors[i], arraysize);
786  break;
787  default:
788  ERREXIT(cinfo, JERR_NOT_COMPILED);
789  break;
790  }
791 }
792 
793 
794 /*
795  * Finish up at the end of the pass.
796  */
797 
798 METHODDEF(void)
800 {
801  /* no work in 1-pass case */
802 }
803 
804 
805 /*
806  * Switch to a new external colormap between output passes.
807  * Shouldn't get to this module!
808  */
809 
810 METHODDEF(void)
812 {
813  ERREXIT(cinfo, JERR_MODE_CHANGE);
814 }
815 
816 
817 /*
818  * Module initialization routine for 1-pass color quantization.
819  */
820 
821 GLOBAL(void)
823 {
824  my_cquantize_ptr cquantize;
825 
826  cquantize = (my_cquantize_ptr)
827  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
829  cinfo->cquantize = (struct jpeg_color_quantizer *) cquantize;
830  cquantize->pub.start_pass = start_pass_1_quant;
831  cquantize->pub.finish_pass = finish_pass_1_quant;
832  cquantize->pub.new_color_map = new_color_map_1_quant;
833  cquantize->fserrors[0] = NULL; /* Flag FS workspace not allocated */
834  cquantize->odither[0] = NULL; /* Also flag odither arrays not allocated */
835 
836  /* Make sure my internal arrays won't overflow */
837  if (cinfo->out_color_components > MAX_Q_COMPS)
838  ERREXIT1(cinfo, JERR_QUANT_COMPONENTS, MAX_Q_COMPS);
839  /* Make sure colormap indexes can be represented by JSAMPLEs */
840  if (cinfo->desired_number_of_colors > (MAXJSAMPLE+1))
841  ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, MAXJSAMPLE+1);
842 
843  /* Create the colormap and color index table. */
844  create_colormap(cinfo);
845  create_colorindex(cinfo);
846 
847  /* Allocate Floyd-Steinberg workspace now if requested.
848  * We do this now since it is FAR storage and may affect the memory
849  * manager's space calculations. If the user changes to FS dither
850  * mode in a later pass, we will allocate the space then, and will
851  * possibly overrun the max_memory_to_use setting.
852  */
853  if (cinfo->dither_mode == JDITHER_FS)
854  alloc_fs_workspace(cinfo);
855 }
856 
857 #endif /* QUANT_1PASS_SUPPORTED */
select_ncolors(j_decompress_ptr cinfo, int Ncolors[])
Definition: jquant1.cpp:184
jzero_far(void FAR *target, size_t bytestozero)
Definition: jutils.cpp:161
char JSAMPLE
Definition: jmorecfg.h:61
GLenum GLenum GLvoid * row
Definition: glew.h:2903
short INT16
Definition: jmorecfg.h:152
alloc_fs_workspace(j_decompress_ptr cinfo)
Definition: jquant1.cpp:722
ODITHER_MATRIX_PTR odither[MAX_Q_COMPS]
Definition: jquant1.cpp:158
quantize_fs_dither(j_decompress_ptr cinfo, JSAMPARRAY input_buf, JSAMPARRAY output_buf, int num_rows)
Definition: jquant1.cpp:610
int ODITHER_MATRIX[ODITHER_SIZE][ODITHER_SIZE]
Definition: jquant1.cpp:74
boolean is_padded
Definition: jquant1.cpp:152
jinit_1pass_quantizer(j_decompress_ptr cinfo)
Definition: jquant1.cpp:822
quantize_ord_dither(j_decompress_ptr cinfo, JSAMPARRAY input_buf, JSAMPARRAY output_buf, int num_rows)
Definition: jquant1.cpp:515
int(* ODITHER_MATRIX_PTR)[ODITHER_SIZE]
Definition: jquant1.cpp:75
struct jpeg_common_struct * j_common_ptr
Definition: mrpt_jpeglib.h:258
GLuint GLuint num
Definition: glew.h:7126
#define GETJSAMPLE(value)
Definition: jmorecfg.h:65
#define ODITHER_CELLS
Definition: jquant1.cpp:71
INT16 FSERROR
Definition: jquant1.cpp:126
#define ERREXIT(cinfo, code)
Definition: jerror.h:199
#define SIZEOF(object)
Definition: jinclude.h:73
#define MAXJSAMPLE
Definition: jmorecfg.h:70
JSAMPLE FAR * JSAMPROW
Definition: mrpt_jpeglib.h:63
void BASE_IMPEXP colormap(const TColormap &color_map, const float color_index, float &r, float &g, float &b)
Transform a float number in the range [0,1] into RGB components.
Definition: color_maps.cpp:101
long INT32
Definition: jmorecfg.h:158
#define SHIFT_TEMPS
Definition: jpegint.h:286
#define ODITHER_SIZE
Definition: jquant1.cpp:69
make_odither_array(j_decompress_ptr cinfo, int ncolors)
Definition: jquant1.cpp:396
start_pass_1_quant(j_decompress_ptr cinfo, boolean is_pre_scan)
Definition: jquant1.cpp:741
int Ncolors[MAX_Q_COMPS]
Definition: jquant1.cpp:154
#define TRACEMS1(cinfo, lvl, code, p1)
Definition: jerror.h:249
JSAMPIMAGE input_buf
Definition: jccoefct.cpp:59
#define MRPT_UNUSED_PARAM(a)
Can be used to avoid "not used parameters" warnings from the compiler.
largest_input_value(j_decompress_ptr cinfo, int ci, int j, int maxj)
Definition: jquant1.cpp:258
#define FALSE
Definition: jmorecfg.h:227
short UINT8
Definition: jmorecfg.h:137
#define JPOOL_IMAGE
Definition: mrpt_jpeglib.h:746
#define LOCAL(type)
Definition: jmorecfg.h:183
JSAMPROW * JSAMPARRAY
Definition: mrpt_jpeglib.h:64
quantize3_ord_dither(j_decompress_ptr cinfo, JSAMPARRAY input_buf, JSAMPARRAY output_buf, int num_rows)
Definition: jquant1.cpp:565
create_colormap(j_decompress_ptr cinfo)
Definition: jquant1.cpp:273
create_odither_tables(j_decompress_ptr cinfo)
Definition: jquant1.cpp:432
typedef int(WINAPI *PFNWGLRELEASEPBUFFERDCARBPROC)(HPBUFFERARB hPbuffer
create_colorindex(j_decompress_ptr cinfo)
Definition: jquant1.cpp:333
int JSAMPARRAY int int num_rows
Definition: jpegint.h:370
new_color_map_1_quant(j_decompress_ptr cinfo)
Definition: jquant1.cpp:811
int LOCFSERROR
Definition: jquant1.cpp:127
#define TRUE
Definition: jmorecfg.h:230
finish_pass_1_quant(j_decompress_ptr)
Definition: jquant1.cpp:799
color_quantize3(j_decompress_ptr cinfo, JSAMPARRAY input_buf, JSAMPARRAY output_buf, int num_rows)
Definition: jquant1.cpp:487
FSERROR FAR * FSERRPTR
Definition: jquant1.cpp:133
#define ERREXIT1(cinfo, code, p1)
Definition: jerror.h:202
struct jpeg_color_quantizer pub
Definition: jquant1.cpp:141
output_value(j_decompress_ptr cinfo, int ci, int j, int maxj)
Definition: jquant1.cpp:243
boolean on_odd_row
Definition: jquant1.cpp:162
JSAMPIMAGE output_buf
Definition: jdcoefct.cpp:59
JSAMPARRAY colorindex
Definition: jquant1.cpp:147
#define GLOBAL(type)
Definition: jmorecfg.h:185
#define METHODDEF(type)
Definition: jmorecfg.h:181
#define RIGHT_SHIFT(x, shft)
Definition: jpegint.h:287
FSERRPTR fserrors[MAX_Q_COMPS]
Definition: jquant1.cpp:161
color_quantize(j_decompress_ptr cinfo, JSAMPARRAY input_buf, JSAMPARRAY output_buf, int num_rows)
Definition: jquant1.cpp:459
GLuint GLfloat * val
Definition: glew.h:7785
static const UINT8 base_dither_matrix[ODITHER_SIZE][ODITHER_SIZE]
Definition: jquant1.cpp:77
unsigned int JDIMENSION
Definition: jmorecfg.h:168
#define TRACEMS4(cinfo, lvl, code, p1, p2, p3, p4)
Definition: jerror.h:263
#define FAR
Definition: zconf.h:261
GLint GLint GLint GLint GLint GLint GLsizei width
Definition: glew.h:1166
JSAMPARRAY sv_colormap
Definition: jquant1.cpp:144
#define MAX_Q_COMPS
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#define ODITHER_MASK
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my_cquantizer * my_cquantize_ptr
Definition: jquant1.cpp:165



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