1 /* pngrtran.c - transforms the data in a row for PNG readers
2 *
3 * Last changed in libpng 1.6.2 [April 25, 2013]
4 * Copyright (c) 1998-2013 Glenn Randers-Pehrson
5 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
6 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
7 *
8 * This code is released under the libpng license.
9 * For conditions of distribution and use, see the disclaimer
10 * and license in png.h
11 *
12 * This file contains functions optionally called by an application
13 * in order to tell libpng how to handle data when reading a PNG.
14 * Transformations that are used in both reading and writing are
15 * in pngtrans.c.
16 */
17
18 #include "pngpriv.h"
19
20 #ifdef PNG_READ_SUPPORTED
21
22 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
23 void PNGAPI
png_set_crc_action(png_structrp png_ptr,int crit_action,int ancil_action)24 png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
25 {
26 png_debug(1, "in png_set_crc_action");
27
28 if (png_ptr == NULL)
29 return;
30
31 /* Tell libpng how we react to CRC errors in critical chunks */
32 switch (crit_action)
33 {
34 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
35 break;
36
37 case PNG_CRC_WARN_USE: /* Warn/use data */
38 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
39 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
40 break;
41
42 case PNG_CRC_QUIET_USE: /* Quiet/use data */
43 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
44 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
45 PNG_FLAG_CRC_CRITICAL_IGNORE;
46 break;
47
48 case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */
49 png_warning(png_ptr,
50 "Can't discard critical data on CRC error");
51 case PNG_CRC_ERROR_QUIT: /* Error/quit */
52
53 case PNG_CRC_DEFAULT:
54 default:
55 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
56 break;
57 }
58
59 /* Tell libpng how we react to CRC errors in ancillary chunks */
60 switch (ancil_action)
61 {
62 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
63 break;
64
65 case PNG_CRC_WARN_USE: /* Warn/use data */
66 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
67 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
68 break;
69
70 case PNG_CRC_QUIET_USE: /* Quiet/use data */
71 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
72 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
73 PNG_FLAG_CRC_ANCILLARY_NOWARN;
74 break;
75
76 case PNG_CRC_ERROR_QUIT: /* Error/quit */
77 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
78 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
79 break;
80
81 case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
82
83 case PNG_CRC_DEFAULT:
84 default:
85 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
86 break;
87 }
88 }
89
90 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
91 /* Is it OK to set a transformation now? Only if png_start_read_image or
92 * png_read_update_info have not been called. It is not necessary for the IHDR
93 * to have been read in all cases, the parameter allows for this check too.
94 */
95 static int
png_rtran_ok(png_structrp png_ptr,int need_IHDR)96 png_rtran_ok(png_structrp png_ptr, int need_IHDR)
97 {
98 if (png_ptr != NULL)
99 {
100 if (png_ptr->flags & PNG_FLAG_ROW_INIT)
101 png_app_error(png_ptr,
102 "invalid after png_start_read_image or png_read_update_info");
103
104 else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
105 png_app_error(png_ptr, "invalid before the PNG header has been read");
106
107 else
108 {
109 /* Turn on failure to initialize correctly for all transforms. */
110 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
111
112 return 1; /* Ok */
113 }
114 }
115
116 return 0; /* no png_error possible! */
117 }
118 #endif
119
120 #ifdef PNG_READ_BACKGROUND_SUPPORTED
121 /* Handle alpha and tRNS via a background color */
122 void PNGFAPI
png_set_background_fixed(png_structrp png_ptr,png_const_color_16p background_color,int background_gamma_code,int need_expand,png_fixed_point background_gamma)123 png_set_background_fixed(png_structrp png_ptr,
124 png_const_color_16p background_color, int background_gamma_code,
125 int need_expand, png_fixed_point background_gamma)
126 {
127 png_debug(1, "in png_set_background_fixed");
128
129 if (!png_rtran_ok(png_ptr, 0) || background_color == NULL)
130 return;
131
132 if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
133 {
134 png_warning(png_ptr, "Application must supply a known background gamma");
135 return;
136 }
137
138 png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
139 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
140 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
141
142 png_ptr->background = *background_color;
143 png_ptr->background_gamma = background_gamma;
144 png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
145 if (need_expand)
146 png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
147 else
148 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
149 }
150
151 # ifdef PNG_FLOATING_POINT_SUPPORTED
152 void PNGAPI
png_set_background(png_structrp png_ptr,png_const_color_16p background_color,int background_gamma_code,int need_expand,double background_gamma)153 png_set_background(png_structrp png_ptr,
154 png_const_color_16p background_color, int background_gamma_code,
155 int need_expand, double background_gamma)
156 {
157 png_set_background_fixed(png_ptr, background_color, background_gamma_code,
158 need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
159 }
160 # endif /* FLOATING_POINT */
161 #endif /* READ_BACKGROUND */
162
163 /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
164 * one that pngrtran does first (scale) happens. This is necessary to allow the
165 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
166 */
167 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
168 void PNGAPI
png_set_scale_16(png_structrp png_ptr)169 png_set_scale_16(png_structrp png_ptr)
170 {
171 png_debug(1, "in png_set_scale_16");
172
173 if (!png_rtran_ok(png_ptr, 0))
174 return;
175
176 png_ptr->transformations |= PNG_SCALE_16_TO_8;
177 }
178 #endif
179
180 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
181 /* Chop 16-bit depth files to 8-bit depth */
182 void PNGAPI
png_set_strip_16(png_structrp png_ptr)183 png_set_strip_16(png_structrp png_ptr)
184 {
185 png_debug(1, "in png_set_strip_16");
186
187 if (!png_rtran_ok(png_ptr, 0))
188 return;
189
190 png_ptr->transformations |= PNG_16_TO_8;
191 }
192 #endif
193
194 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
195 void PNGAPI
png_set_strip_alpha(png_structrp png_ptr)196 png_set_strip_alpha(png_structrp png_ptr)
197 {
198 png_debug(1, "in png_set_strip_alpha");
199
200 if (!png_rtran_ok(png_ptr, 0))
201 return;
202
203 png_ptr->transformations |= PNG_STRIP_ALPHA;
204 }
205 #endif
206
207 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
208 static png_fixed_point
translate_gamma_flags(png_structrp png_ptr,png_fixed_point output_gamma,int is_screen)209 translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
210 int is_screen)
211 {
212 /* Check for flag values. The main reason for having the old Mac value as a
213 * flag is that it is pretty near impossible to work out what the correct
214 * value is from Apple documentation - a working Mac system is needed to
215 * discover the value!
216 */
217 if (output_gamma == PNG_DEFAULT_sRGB ||
218 output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
219 {
220 /* If there is no sRGB support this just sets the gamma to the standard
221 * sRGB value. (This is a side effect of using this function!)
222 */
223 # ifdef PNG_READ_sRGB_SUPPORTED
224 png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
225 # else
226 PNG_UNUSED(png_ptr)
227 # endif
228 if (is_screen)
229 output_gamma = PNG_GAMMA_sRGB;
230 else
231 output_gamma = PNG_GAMMA_sRGB_INVERSE;
232 }
233
234 else if (output_gamma == PNG_GAMMA_MAC_18 ||
235 output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
236 {
237 if (is_screen)
238 output_gamma = PNG_GAMMA_MAC_OLD;
239 else
240 output_gamma = PNG_GAMMA_MAC_INVERSE;
241 }
242
243 return output_gamma;
244 }
245
246 # ifdef PNG_FLOATING_POINT_SUPPORTED
247 static png_fixed_point
convert_gamma_value(png_structrp png_ptr,double output_gamma)248 convert_gamma_value(png_structrp png_ptr, double output_gamma)
249 {
250 /* The following silently ignores cases where fixed point (times 100,000)
251 * gamma values are passed to the floating point API. This is safe and it
252 * means the fixed point constants work just fine with the floating point
253 * API. The alternative would just lead to undetected errors and spurious
254 * bug reports. Negative values fail inside the _fixed API unless they
255 * correspond to the flag values.
256 */
257 if (output_gamma > 0 && output_gamma < 128)
258 output_gamma *= PNG_FP_1;
259
260 /* This preserves -1 and -2 exactly: */
261 output_gamma = floor(output_gamma + .5);
262
263 if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
264 png_fixed_error(png_ptr, "gamma value");
265
266 return (png_fixed_point)output_gamma;
267 }
268 # endif
269 #endif /* READ_ALPHA_MODE || READ_GAMMA */
270
271 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
272 void PNGFAPI
png_set_alpha_mode_fixed(png_structrp png_ptr,int mode,png_fixed_point output_gamma)273 png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
274 png_fixed_point output_gamma)
275 {
276 int compose = 0;
277 png_fixed_point file_gamma;
278
279 png_debug(1, "in png_set_alpha_mode");
280
281 if (!png_rtran_ok(png_ptr, 0))
282 return;
283
284 output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
285
286 /* Validate the value to ensure it is in a reasonable range. The value
287 * is expected to be 1 or greater, but this range test allows for some
288 * viewing correction values. The intent is to weed out users of this API
289 * who use the inverse of the gamma value accidentally! Since some of these
290 * values are reasonable this may have to be changed.
291 */
292 if (output_gamma < 70000 || output_gamma > 300000)
293 png_error(png_ptr, "output gamma out of expected range");
294
295 /* The default file gamma is the inverse of the output gamma; the output
296 * gamma may be changed below so get the file value first:
297 */
298 file_gamma = png_reciprocal(output_gamma);
299
300 /* There are really 8 possibilities here, composed of any combination
301 * of:
302 *
303 * premultiply the color channels
304 * do not encode non-opaque pixels
305 * encode the alpha as well as the color channels
306 *
307 * The differences disappear if the input/output ('screen') gamma is 1.0,
308 * because then the encoding is a no-op and there is only the choice of
309 * premultiplying the color channels or not.
310 *
311 * png_set_alpha_mode and png_set_background interact because both use
312 * png_compose to do the work. Calling both is only useful when
313 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
314 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
315 */
316 switch (mode)
317 {
318 case PNG_ALPHA_PNG: /* default: png standard */
319 /* No compose, but it may be set by png_set_background! */
320 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
321 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
322 break;
323
324 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
325 compose = 1;
326 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
327 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
328 /* The output is linear: */
329 output_gamma = PNG_FP_1;
330 break;
331
332 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
333 compose = 1;
334 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
335 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
336 /* output_gamma records the encoding of opaque pixels! */
337 break;
338
339 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
340 compose = 1;
341 png_ptr->transformations |= PNG_ENCODE_ALPHA;
342 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
343 break;
344
345 default:
346 png_error(png_ptr, "invalid alpha mode");
347 }
348
349 /* Only set the default gamma if the file gamma has not been set (this has
350 * the side effect that the gamma in a second call to png_set_alpha_mode will
351 * be ignored.)
352 */
353 if (png_ptr->colorspace.gamma == 0)
354 {
355 png_ptr->colorspace.gamma = file_gamma;
356 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
357 }
358
359 /* But always set the output gamma: */
360 png_ptr->screen_gamma = output_gamma;
361
362 /* Finally, if pre-multiplying, set the background fields to achieve the
363 * desired result.
364 */
365 if (compose)
366 {
367 /* And obtain alpha pre-multiplication by composing on black: */
368 memset(&png_ptr->background, 0, (sizeof png_ptr->background));
369 png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
370 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
371 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
372
373 if (png_ptr->transformations & PNG_COMPOSE)
374 png_error(png_ptr,
375 "conflicting calls to set alpha mode and background");
376
377 png_ptr->transformations |= PNG_COMPOSE;
378 }
379 }
380
381 # ifdef PNG_FLOATING_POINT_SUPPORTED
382 void PNGAPI
png_set_alpha_mode(png_structrp png_ptr,int mode,double output_gamma)383 png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
384 {
385 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
386 output_gamma));
387 }
388 # endif
389 #endif
390
391 #ifdef PNG_READ_QUANTIZE_SUPPORTED
392 /* Dither file to 8-bit. Supply a palette, the current number
393 * of elements in the palette, the maximum number of elements
394 * allowed, and a histogram if possible. If the current number
395 * of colors is greater then the maximum number, the palette will be
396 * modified to fit in the maximum number. "full_quantize" indicates
397 * whether we need a quantizing cube set up for RGB images, or if we
398 * simply are reducing the number of colors in a paletted image.
399 */
400
401 typedef struct png_dsort_struct
402 {
403 struct png_dsort_struct * next;
404 png_byte left;
405 png_byte right;
406 } png_dsort;
407 typedef png_dsort * png_dsortp;
408 typedef png_dsort * * png_dsortpp;
409
410 void PNGAPI
png_set_quantize(png_structrp png_ptr,png_colorp palette,int num_palette,int maximum_colors,png_const_uint_16p histogram,int full_quantize)411 png_set_quantize(png_structrp png_ptr, png_colorp palette,
412 int num_palette, int maximum_colors, png_const_uint_16p histogram,
413 int full_quantize)
414 {
415 png_debug(1, "in png_set_quantize");
416
417 if (!png_rtran_ok(png_ptr, 0))
418 return;
419
420 png_ptr->transformations |= PNG_QUANTIZE;
421
422 if (!full_quantize)
423 {
424 int i;
425
426 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
427 (png_uint_32)(num_palette * (sizeof (png_byte))));
428 for (i = 0; i < num_palette; i++)
429 png_ptr->quantize_index[i] = (png_byte)i;
430 }
431
432 if (num_palette > maximum_colors)
433 {
434 if (histogram != NULL)
435 {
436 /* This is easy enough, just throw out the least used colors.
437 * Perhaps not the best solution, but good enough.
438 */
439
440 int i;
441
442 /* Initialize an array to sort colors */
443 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
444 (png_uint_32)(num_palette * (sizeof (png_byte))));
445
446 /* Initialize the quantize_sort array */
447 for (i = 0; i < num_palette; i++)
448 png_ptr->quantize_sort[i] = (png_byte)i;
449
450 /* Find the least used palette entries by starting a
451 * bubble sort, and running it until we have sorted
452 * out enough colors. Note that we don't care about
453 * sorting all the colors, just finding which are
454 * least used.
455 */
456
457 for (i = num_palette - 1; i >= maximum_colors; i--)
458 {
459 int done; /* To stop early if the list is pre-sorted */
460 int j;
461
462 done = 1;
463 for (j = 0; j < i; j++)
464 {
465 if (histogram[png_ptr->quantize_sort[j]]
466 < histogram[png_ptr->quantize_sort[j + 1]])
467 {
468 png_byte t;
469
470 t = png_ptr->quantize_sort[j];
471 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
472 png_ptr->quantize_sort[j + 1] = t;
473 done = 0;
474 }
475 }
476
477 if (done)
478 break;
479 }
480
481 /* Swap the palette around, and set up a table, if necessary */
482 if (full_quantize)
483 {
484 int j = num_palette;
485
486 /* Put all the useful colors within the max, but don't
487 * move the others.
488 */
489 for (i = 0; i < maximum_colors; i++)
490 {
491 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
492 {
493 do
494 j--;
495 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
496
497 palette[i] = palette[j];
498 }
499 }
500 }
501 else
502 {
503 int j = num_palette;
504
505 /* Move all the used colors inside the max limit, and
506 * develop a translation table.
507 */
508 for (i = 0; i < maximum_colors; i++)
509 {
510 /* Only move the colors we need to */
511 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
512 {
513 png_color tmp_color;
514
515 do
516 j--;
517 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
518
519 tmp_color = palette[j];
520 palette[j] = palette[i];
521 palette[i] = tmp_color;
522 /* Indicate where the color went */
523 png_ptr->quantize_index[j] = (png_byte)i;
524 png_ptr->quantize_index[i] = (png_byte)j;
525 }
526 }
527
528 /* Find closest color for those colors we are not using */
529 for (i = 0; i < num_palette; i++)
530 {
531 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
532 {
533 int min_d, k, min_k, d_index;
534
535 /* Find the closest color to one we threw out */
536 d_index = png_ptr->quantize_index[i];
537 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
538 for (k = 1, min_k = 0; k < maximum_colors; k++)
539 {
540 int d;
541
542 d = PNG_COLOR_DIST(palette[d_index], palette[k]);
543
544 if (d < min_d)
545 {
546 min_d = d;
547 min_k = k;
548 }
549 }
550 /* Point to closest color */
551 png_ptr->quantize_index[i] = (png_byte)min_k;
552 }
553 }
554 }
555 png_free(png_ptr, png_ptr->quantize_sort);
556 png_ptr->quantize_sort = NULL;
557 }
558 else
559 {
560 /* This is much harder to do simply (and quickly). Perhaps
561 * we need to go through a median cut routine, but those
562 * don't always behave themselves with only a few colors
563 * as input. So we will just find the closest two colors,
564 * and throw out one of them (chosen somewhat randomly).
565 * [We don't understand this at all, so if someone wants to
566 * work on improving it, be our guest - AED, GRP]
567 */
568 int i;
569 int max_d;
570 int num_new_palette;
571 png_dsortp t;
572 png_dsortpp hash;
573
574 t = NULL;
575
576 /* Initialize palette index arrays */
577 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
578 (png_uint_32)(num_palette * (sizeof (png_byte))));
579 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
580 (png_uint_32)(num_palette * (sizeof (png_byte))));
581
582 /* Initialize the sort array */
583 for (i = 0; i < num_palette; i++)
584 {
585 png_ptr->index_to_palette[i] = (png_byte)i;
586 png_ptr->palette_to_index[i] = (png_byte)i;
587 }
588
589 hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
590 (sizeof (png_dsortp))));
591
592 num_new_palette = num_palette;
593
594 /* Initial wild guess at how far apart the farthest pixel
595 * pair we will be eliminating will be. Larger
596 * numbers mean more areas will be allocated, Smaller
597 * numbers run the risk of not saving enough data, and
598 * having to do this all over again.
599 *
600 * I have not done extensive checking on this number.
601 */
602 max_d = 96;
603
604 while (num_new_palette > maximum_colors)
605 {
606 for (i = 0; i < num_new_palette - 1; i++)
607 {
608 int j;
609
610 for (j = i + 1; j < num_new_palette; j++)
611 {
612 int d;
613
614 d = PNG_COLOR_DIST(palette[i], palette[j]);
615
616 if (d <= max_d)
617 {
618
619 t = (png_dsortp)png_malloc_warn(png_ptr,
620 (png_uint_32)(sizeof (png_dsort)));
621
622 if (t == NULL)
623 break;
624
625 t->next = hash[d];
626 t->left = (png_byte)i;
627 t->right = (png_byte)j;
628 hash[d] = t;
629 }
630 }
631 if (t == NULL)
632 break;
633 }
634
635 if (t != NULL)
636 for (i = 0; i <= max_d; i++)
637 {
638 if (hash[i] != NULL)
639 {
640 png_dsortp p;
641
642 for (p = hash[i]; p; p = p->next)
643 {
644 if ((int)png_ptr->index_to_palette[p->left]
645 < num_new_palette &&
646 (int)png_ptr->index_to_palette[p->right]
647 < num_new_palette)
648 {
649 int j, next_j;
650
651 if (num_new_palette & 0x01)
652 {
653 j = p->left;
654 next_j = p->right;
655 }
656 else
657 {
658 j = p->right;
659 next_j = p->left;
660 }
661
662 num_new_palette--;
663 palette[png_ptr->index_to_palette[j]]
664 = palette[num_new_palette];
665 if (!full_quantize)
666 {
667 int k;
668
669 for (k = 0; k < num_palette; k++)
670 {
671 if (png_ptr->quantize_index[k] ==
672 png_ptr->index_to_palette[j])
673 png_ptr->quantize_index[k] =
674 png_ptr->index_to_palette[next_j];
675
676 if ((int)png_ptr->quantize_index[k] ==
677 num_new_palette)
678 png_ptr->quantize_index[k] =
679 png_ptr->index_to_palette[j];
680 }
681 }
682
683 png_ptr->index_to_palette[png_ptr->palette_to_index
684 [num_new_palette]] = png_ptr->index_to_palette[j];
685
686 png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
687 = png_ptr->palette_to_index[num_new_palette];
688
689 png_ptr->index_to_palette[j] =
690 (png_byte)num_new_palette;
691
692 png_ptr->palette_to_index[num_new_palette] =
693 (png_byte)j;
694 }
695 if (num_new_palette <= maximum_colors)
696 break;
697 }
698 if (num_new_palette <= maximum_colors)
699 break;
700 }
701 }
702
703 for (i = 0; i < 769; i++)
704 {
705 if (hash[i] != NULL)
706 {
707 png_dsortp p = hash[i];
708 while (p)
709 {
710 t = p->next;
711 png_free(png_ptr, p);
712 p = t;
713 }
714 }
715 hash[i] = 0;
716 }
717 max_d += 96;
718 }
719 png_free(png_ptr, hash);
720 png_free(png_ptr, png_ptr->palette_to_index);
721 png_free(png_ptr, png_ptr->index_to_palette);
722 png_ptr->palette_to_index = NULL;
723 png_ptr->index_to_palette = NULL;
724 }
725 num_palette = maximum_colors;
726 }
727 if (png_ptr->palette == NULL)
728 {
729 png_ptr->palette = palette;
730 }
731 png_ptr->num_palette = (png_uint_16)num_palette;
732
733 if (full_quantize)
734 {
735 int i;
736 png_bytep distance;
737 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
738 PNG_QUANTIZE_BLUE_BITS;
739 int num_red = (1 << PNG_QUANTIZE_RED_BITS);
740 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
741 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
742 png_size_t num_entries = ((png_size_t)1 << total_bits);
743
744 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
745 (png_uint_32)(num_entries * (sizeof (png_byte))));
746
747 distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
748 (sizeof (png_byte))));
749
750 memset(distance, 0xff, num_entries * (sizeof (png_byte)));
751
752 for (i = 0; i < num_palette; i++)
753 {
754 int ir, ig, ib;
755 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
756 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
757 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
758
759 for (ir = 0; ir < num_red; ir++)
760 {
761 /* int dr = abs(ir - r); */
762 int dr = ((ir > r) ? ir - r : r - ir);
763 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
764 PNG_QUANTIZE_GREEN_BITS));
765
766 for (ig = 0; ig < num_green; ig++)
767 {
768 /* int dg = abs(ig - g); */
769 int dg = ((ig > g) ? ig - g : g - ig);
770 int dt = dr + dg;
771 int dm = ((dr > dg) ? dr : dg);
772 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
773
774 for (ib = 0; ib < num_blue; ib++)
775 {
776 int d_index = index_g | ib;
777 /* int db = abs(ib - b); */
778 int db = ((ib > b) ? ib - b : b - ib);
779 int dmax = ((dm > db) ? dm : db);
780 int d = dmax + dt + db;
781
782 if (d < (int)distance[d_index])
783 {
784 distance[d_index] = (png_byte)d;
785 png_ptr->palette_lookup[d_index] = (png_byte)i;
786 }
787 }
788 }
789 }
790 }
791
792 png_free(png_ptr, distance);
793 }
794 }
795 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
796
797 #ifdef PNG_READ_GAMMA_SUPPORTED
798 void PNGFAPI
png_set_gamma_fixed(png_structrp png_ptr,png_fixed_point scrn_gamma,png_fixed_point file_gamma)799 png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
800 png_fixed_point file_gamma)
801 {
802 png_debug(1, "in png_set_gamma_fixed");
803
804 if (!png_rtran_ok(png_ptr, 0))
805 return;
806
807 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
808 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
809 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
810
811 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
812 * premultiplied alpha support; this actually hides an undocumented feature
813 * of the previous implementation which allowed gamma processing to be
814 * disabled in background handling. There is no evidence (so far) that this
815 * was being used; however, png_set_background itself accepted and must still
816 * accept '0' for the gamma value it takes, because it isn't always used.
817 *
818 * Since this is an API change (albeit a very minor one that removes an
819 * undocumented API feature) the following checks were only enabled in
820 * libpng-1.6.0.
821 */
822 if (file_gamma <= 0)
823 png_error(png_ptr, "invalid file gamma in png_set_gamma");
824
825 if (scrn_gamma <= 0)
826 png_error(png_ptr, "invalid screen gamma in png_set_gamma");
827
828 /* Set the gamma values unconditionally - this overrides the value in the PNG
829 * file if a gAMA chunk was present. png_set_alpha_mode provides a
830 * different, easier, way to default the file gamma.
831 */
832 png_ptr->colorspace.gamma = file_gamma;
833 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
834 png_ptr->screen_gamma = scrn_gamma;
835 }
836
837 # ifdef PNG_FLOATING_POINT_SUPPORTED
838 void PNGAPI
png_set_gamma(png_structrp png_ptr,double scrn_gamma,double file_gamma)839 png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
840 {
841 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
842 convert_gamma_value(png_ptr, file_gamma));
843 }
844 # endif /* FLOATING_POINT_SUPPORTED */
845 #endif /* READ_GAMMA */
846
847 #ifdef PNG_READ_EXPAND_SUPPORTED
848 /* Expand paletted images to RGB, expand grayscale images of
849 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
850 * to alpha channels.
851 */
852 void PNGAPI
png_set_expand(png_structrp png_ptr)853 png_set_expand(png_structrp png_ptr)
854 {
855 png_debug(1, "in png_set_expand");
856
857 if (!png_rtran_ok(png_ptr, 0))
858 return;
859
860 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
861 }
862
863 /* GRR 19990627: the following three functions currently are identical
864 * to png_set_expand(). However, it is entirely reasonable that someone
865 * might wish to expand an indexed image to RGB but *not* expand a single,
866 * fully transparent palette entry to a full alpha channel--perhaps instead
867 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
868 * the transparent color with a particular RGB value, or drop tRNS entirely.
869 * IOW, a future version of the library may make the transformations flag
870 * a bit more fine-grained, with separate bits for each of these three
871 * functions.
872 *
873 * More to the point, these functions make it obvious what libpng will be
874 * doing, whereas "expand" can (and does) mean any number of things.
875 *
876 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
877 * to expand only the sample depth but not to expand the tRNS to alpha
878 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
879 */
880
881 /* Expand paletted images to RGB. */
882 void PNGAPI
png_set_palette_to_rgb(png_structrp png_ptr)883 png_set_palette_to_rgb(png_structrp png_ptr)
884 {
885 png_debug(1, "in png_set_palette_to_rgb");
886
887 if (!png_rtran_ok(png_ptr, 0))
888 return;
889
890 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
891 }
892
893 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
894 void PNGAPI
png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)895 png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
896 {
897 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
898
899 if (!png_rtran_ok(png_ptr, 0))
900 return;
901
902 png_ptr->transformations |= PNG_EXPAND;
903 }
904
905 /* Expand tRNS chunks to alpha channels. */
906 void PNGAPI
png_set_tRNS_to_alpha(png_structrp png_ptr)907 png_set_tRNS_to_alpha(png_structrp png_ptr)
908 {
909 png_debug(1, "in png_set_tRNS_to_alpha");
910
911 if (!png_rtran_ok(png_ptr, 0))
912 return;
913
914 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
915 }
916 #endif /* defined(PNG_READ_EXPAND_SUPPORTED) */
917
918 #ifdef PNG_READ_EXPAND_16_SUPPORTED
919 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
920 * it may not work correctly.)
921 */
922 void PNGAPI
png_set_expand_16(png_structrp png_ptr)923 png_set_expand_16(png_structrp png_ptr)
924 {
925 png_debug(1, "in png_set_expand_16");
926
927 if (!png_rtran_ok(png_ptr, 0))
928 return;
929
930 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
931 }
932 #endif
933
934 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
935 void PNGAPI
png_set_gray_to_rgb(png_structrp png_ptr)936 png_set_gray_to_rgb(png_structrp png_ptr)
937 {
938 png_debug(1, "in png_set_gray_to_rgb");
939
940 if (!png_rtran_ok(png_ptr, 0))
941 return;
942
943 /* Because rgb must be 8 bits or more: */
944 png_set_expand_gray_1_2_4_to_8(png_ptr);
945 png_ptr->transformations |= PNG_GRAY_TO_RGB;
946 }
947 #endif
948
949 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
950 void PNGFAPI
png_set_rgb_to_gray_fixed(png_structrp png_ptr,int error_action,png_fixed_point red,png_fixed_point green)951 png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
952 png_fixed_point red, png_fixed_point green)
953 {
954 png_debug(1, "in png_set_rgb_to_gray");
955
956 /* Need the IHDR here because of the check on color_type below. */
957 /* TODO: fix this */
958 if (!png_rtran_ok(png_ptr, 1))
959 return;
960
961 switch(error_action)
962 {
963 case PNG_ERROR_ACTION_NONE:
964 png_ptr->transformations |= PNG_RGB_TO_GRAY;
965 break;
966
967 case PNG_ERROR_ACTION_WARN:
968 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
969 break;
970
971 case PNG_ERROR_ACTION_ERROR:
972 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
973 break;
974
975 default:
976 png_error(png_ptr, "invalid error action to rgb_to_gray");
977 break;
978 }
979
980 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
981 #ifdef PNG_READ_EXPAND_SUPPORTED
982 png_ptr->transformations |= PNG_EXPAND;
983 #else
984 {
985 /* Make this an error in 1.6 because otherwise the application may assume
986 * that it just worked and get a memory overwrite.
987 */
988 png_error(png_ptr,
989 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
990
991 /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
992 }
993 #endif
994 {
995 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
996 {
997 png_uint_16 red_int, green_int;
998
999 /* NOTE: this calculation does not round, but this behavior is retained
1000 * for consistency, the inaccuracy is very small. The code here always
1001 * overwrites the coefficients, regardless of whether they have been
1002 * defaulted or set already.
1003 */
1004 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
1005 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
1006
1007 png_ptr->rgb_to_gray_red_coeff = red_int;
1008 png_ptr->rgb_to_gray_green_coeff = green_int;
1009 png_ptr->rgb_to_gray_coefficients_set = 1;
1010 }
1011
1012 else
1013 {
1014 if (red >= 0 && green >= 0)
1015 png_app_warning(png_ptr,
1016 "ignoring out of range rgb_to_gray coefficients");
1017
1018 /* Use the defaults, from the cHRM chunk if set, else the historical
1019 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
1020 * png_do_rgb_to_gray for more discussion of the values. In this case
1021 * the coefficients are not marked as 'set' and are not overwritten if
1022 * something has already provided a default.
1023 */
1024 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
1025 png_ptr->rgb_to_gray_green_coeff == 0)
1026 {
1027 png_ptr->rgb_to_gray_red_coeff = 6968;
1028 png_ptr->rgb_to_gray_green_coeff = 23434;
1029 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1030 }
1031 }
1032 }
1033 }
1034
1035 #ifdef PNG_FLOATING_POINT_SUPPORTED
1036 /* Convert a RGB image to a grayscale of the same width. This allows us,
1037 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1038 */
1039
1040 void PNGAPI
png_set_rgb_to_gray(png_structrp png_ptr,int error_action,double red,double green)1041 png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
1042 double green)
1043 {
1044 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1045 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
1046 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
1047 }
1048 #endif /* FLOATING POINT */
1049
1050 #endif /* RGB_TO_GRAY */
1051
1052 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1053 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1054 void PNGAPI
png_set_read_user_transform_fn(png_structrp png_ptr,png_user_transform_ptr read_user_transform_fn)1055 png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1056 read_user_transform_fn)
1057 {
1058 png_debug(1, "in png_set_read_user_transform_fn");
1059
1060 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1061 png_ptr->transformations |= PNG_USER_TRANSFORM;
1062 png_ptr->read_user_transform_fn = read_user_transform_fn;
1063 #endif
1064 }
1065 #endif
1066
1067 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1068 #ifdef PNG_READ_GAMMA_SUPPORTED
1069 /* In the case of gamma transformations only do transformations on images where
1070 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1071 * slows things down slightly, and also needlessly introduces small errors.
1072 */
1073 static int /* PRIVATE */
png_gamma_threshold(png_fixed_point screen_gamma,png_fixed_point file_gamma)1074 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
1075 {
1076 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1077 * correction as a difference of the overall transform from 1.0
1078 *
1079 * We want to compare the threshold with s*f - 1, if we get
1080 * overflow here it is because of wacky gamma values so we
1081 * turn on processing anyway.
1082 */
1083 png_fixed_point gtest;
1084 return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) ||
1085 png_gamma_significant(gtest);
1086 }
1087 #endif
1088
1089 /* Initialize everything needed for the read. This includes modifying
1090 * the palette.
1091 */
1092
1093 /*For the moment 'png_init_palette_transformations' and
1094 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1095 * The intent is that these two routines should have palette or rgb operations
1096 * extracted from 'png_init_read_transformations'.
1097 */
1098 static void /* PRIVATE */
png_init_palette_transformations(png_structrp png_ptr)1099 png_init_palette_transformations(png_structrp png_ptr)
1100 {
1101 /* Called to handle the (input) palette case. In png_do_read_transformations
1102 * the first step is to expand the palette if requested, so this code must
1103 * take care to only make changes that are invariant with respect to the
1104 * palette expansion, or only do them if there is no expansion.
1105 *
1106 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1107 * to 0.)
1108 */
1109 int input_has_alpha = 0;
1110 int input_has_transparency = 0;
1111
1112 if (png_ptr->num_trans > 0)
1113 {
1114 int i;
1115
1116 /* Ignore if all the entries are opaque (unlikely!) */
1117 for (i=0; i<png_ptr->num_trans; ++i)
1118 if (png_ptr->trans_alpha[i] == 255)
1119 continue;
1120 else if (png_ptr->trans_alpha[i] == 0)
1121 input_has_transparency = 1;
1122 else
1123 input_has_alpha = 1;
1124 }
1125
1126 /* If no alpha we can optimize. */
1127 if (!input_has_alpha)
1128 {
1129 /* Any alpha means background and associative alpha processing is
1130 * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
1131 * and ENCODE_ALPHA are irrelevant.
1132 */
1133 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1134 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1135
1136 if (!input_has_transparency)
1137 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1138 }
1139
1140 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1141 /* png_set_background handling - deals with the complexity of whether the
1142 * background color is in the file format or the screen format in the case
1143 * where an 'expand' will happen.
1144 */
1145
1146 /* The following code cannot be entered in the alpha pre-multiplication case
1147 * because PNG_BACKGROUND_EXPAND is cancelled below.
1148 */
1149 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1150 (png_ptr->transformations & PNG_EXPAND))
1151 {
1152 {
1153 png_ptr->background.red =
1154 png_ptr->palette[png_ptr->background.index].red;
1155 png_ptr->background.green =
1156 png_ptr->palette[png_ptr->background.index].green;
1157 png_ptr->background.blue =
1158 png_ptr->palette[png_ptr->background.index].blue;
1159
1160 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1161 if (png_ptr->transformations & PNG_INVERT_ALPHA)
1162 {
1163 if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
1164 {
1165 /* Invert the alpha channel (in tRNS) unless the pixels are
1166 * going to be expanded, in which case leave it for later
1167 */
1168 int i, istop = png_ptr->num_trans;
1169
1170 for (i=0; i<istop; i++)
1171 png_ptr->trans_alpha[i] = (png_byte)(255 -
1172 png_ptr->trans_alpha[i]);
1173 }
1174 }
1175 #endif /* PNG_READ_INVERT_ALPHA_SUPPORTED */
1176 }
1177 } /* background expand and (therefore) no alpha association. */
1178 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
1179 }
1180
1181 static void /* PRIVATE */
png_init_rgb_transformations(png_structrp png_ptr)1182 png_init_rgb_transformations(png_structrp png_ptr)
1183 {
1184 /* Added to libpng-1.5.4: check the color type to determine whether there
1185 * is any alpha or transparency in the image and simply cancel the
1186 * background and alpha mode stuff if there isn't.
1187 */
1188 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
1189 int input_has_transparency = png_ptr->num_trans > 0;
1190
1191 /* If no alpha we can optimize. */
1192 if (!input_has_alpha)
1193 {
1194 /* Any alpha means background and associative alpha processing is
1195 * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
1196 * and ENCODE_ALPHA are irrelevant.
1197 */
1198 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1199 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1200 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1201 # endif
1202
1203 if (!input_has_transparency)
1204 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1205 }
1206
1207 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1208 /* png_set_background handling - deals with the complexity of whether the
1209 * background color is in the file format or the screen format in the case
1210 * where an 'expand' will happen.
1211 */
1212
1213 /* The following code cannot be entered in the alpha pre-multiplication case
1214 * because PNG_BACKGROUND_EXPAND is cancelled below.
1215 */
1216 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1217 (png_ptr->transformations & PNG_EXPAND) &&
1218 !(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
1219 /* i.e., GRAY or GRAY_ALPHA */
1220 {
1221 {
1222 /* Expand background and tRNS chunks */
1223 int gray = png_ptr->background.gray;
1224 int trans_gray = png_ptr->trans_color.gray;
1225
1226 switch (png_ptr->bit_depth)
1227 {
1228 case 1:
1229 gray *= 0xff;
1230 trans_gray *= 0xff;
1231 break;
1232
1233 case 2:
1234 gray *= 0x55;
1235 trans_gray *= 0x55;
1236 break;
1237
1238 case 4:
1239 gray *= 0x11;
1240 trans_gray *= 0x11;
1241 break;
1242
1243 default:
1244
1245 case 8:
1246 /* FALL THROUGH (Already 8 bits) */
1247
1248 case 16:
1249 /* Already a full 16 bits */
1250 break;
1251 }
1252
1253 png_ptr->background.red = png_ptr->background.green =
1254 png_ptr->background.blue = (png_uint_16)gray;
1255
1256 if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
1257 {
1258 png_ptr->trans_color.red = png_ptr->trans_color.green =
1259 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
1260 }
1261 }
1262 } /* background expand and (therefore) no alpha association. */
1263 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
1264 }
1265
1266 void /* PRIVATE */
png_init_read_transformations(png_structrp png_ptr)1267 png_init_read_transformations(png_structrp png_ptr)
1268 {
1269 png_debug(1, "in png_init_read_transformations");
1270
1271 /* This internal function is called from png_read_start_row in pngrutil.c
1272 * and it is called before the 'rowbytes' calculation is done, so the code
1273 * in here can change or update the transformations flags.
1274 *
1275 * First do updates that do not depend on the details of the PNG image data
1276 * being processed.
1277 */
1278
1279 #ifdef PNG_READ_GAMMA_SUPPORTED
1280 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1281 * png_set_alpha_mode and this is another source for a default file gamma so
1282 * the test needs to be performed later - here. In addition prior to 1.5.4
1283 * the tests were repeated for the PALETTE color type here - this is no
1284 * longer necessary (and doesn't seem to have been necessary before.)
1285 */
1286 {
1287 /* The following temporary indicates if overall gamma correction is
1288 * required.
1289 */
1290 int gamma_correction = 0;
1291
1292 if (png_ptr->colorspace.gamma != 0) /* has been set */
1293 {
1294 if (png_ptr->screen_gamma != 0) /* screen set too */
1295 gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
1296 png_ptr->screen_gamma);
1297
1298 else
1299 /* Assume the output matches the input; a long time default behavior
1300 * of libpng, although the standard has nothing to say about this.
1301 */
1302 png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
1303 }
1304
1305 else if (png_ptr->screen_gamma != 0)
1306 /* The converse - assume the file matches the screen, note that this
1307 * perhaps undesireable default can (from 1.5.4) be changed by calling
1308 * png_set_alpha_mode (even if the alpha handling mode isn't required
1309 * or isn't changed from the default.)
1310 */
1311 png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
1312
1313 else /* neither are set */
1314 /* Just in case the following prevents any processing - file and screen
1315 * are both assumed to be linear and there is no way to introduce a
1316 * third gamma value other than png_set_background with 'UNIQUE', and,
1317 * prior to 1.5.4
1318 */
1319 png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
1320
1321 /* We have a gamma value now. */
1322 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
1323
1324 /* Now turn the gamma transformation on or off as appropriate. Notice
1325 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1326 * composition may independently cause gamma correction because it needs
1327 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1328 * hasn't been specified.) In any case this flag may get turned off in
1329 * the code immediately below if the transform can be handled outside the
1330 * row loop.
1331 */
1332 if (gamma_correction)
1333 png_ptr->transformations |= PNG_GAMMA;
1334
1335 else
1336 png_ptr->transformations &= ~PNG_GAMMA;
1337 }
1338 #endif
1339
1340 /* Certain transformations have the effect of preventing other
1341 * transformations that happen afterward in png_do_read_transformations,
1342 * resolve the interdependencies here. From the code of
1343 * png_do_read_transformations the order is:
1344 *
1345 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1346 * 2) PNG_STRIP_ALPHA (if no compose)
1347 * 3) PNG_RGB_TO_GRAY
1348 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1349 * 5) PNG_COMPOSE
1350 * 6) PNG_GAMMA
1351 * 7) PNG_STRIP_ALPHA (if compose)
1352 * 8) PNG_ENCODE_ALPHA
1353 * 9) PNG_SCALE_16_TO_8
1354 * 10) PNG_16_TO_8
1355 * 11) PNG_QUANTIZE (converts to palette)
1356 * 12) PNG_EXPAND_16
1357 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1358 * 14) PNG_INVERT_MONO
1359 * 15) PNG_SHIFT
1360 * 16) PNG_PACK
1361 * 17) PNG_BGR
1362 * 18) PNG_PACKSWAP
1363 * 19) PNG_FILLER (includes PNG_ADD_ALPHA)
1364 * 20) PNG_INVERT_ALPHA
1365 * 21) PNG_SWAP_ALPHA
1366 * 22) PNG_SWAP_BYTES
1367 * 23) PNG_USER_TRANSFORM [must be last]
1368 */
1369 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1370 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
1371 !(png_ptr->transformations & PNG_COMPOSE))
1372 {
1373 /* Stripping the alpha channel happens immediately after the 'expand'
1374 * transformations, before all other transformation, so it cancels out
1375 * the alpha handling. It has the side effect negating the effect of
1376 * PNG_EXPAND_tRNS too:
1377 */
1378 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
1379 PNG_EXPAND_tRNS);
1380 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1381
1382 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1383 * so transparency information would remain just so long as it wasn't
1384 * expanded. This produces unexpected API changes if the set of things
1385 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1386 * documentation - which says ask for what you want, accept what you
1387 * get.) This makes the behavior consistent from 1.5.4:
1388 */
1389 png_ptr->num_trans = 0;
1390 }
1391 #endif /* STRIP_ALPHA supported, no COMPOSE */
1392
1393 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1394 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1395 * settings will have no effect.
1396 */
1397 if (!png_gamma_significant(png_ptr->screen_gamma))
1398 {
1399 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1400 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1401 }
1402 #endif
1403
1404 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1405 /* Make sure the coefficients for the rgb to gray conversion are set
1406 * appropriately.
1407 */
1408 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
1409 png_colorspace_set_rgb_coefficients(png_ptr);
1410 #endif
1411
1412 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1413 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1414 /* Detect gray background and attempt to enable optimization for
1415 * gray --> RGB case.
1416 *
1417 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1418 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1419 * background color might actually be gray yet not be flagged as such.
1420 * This is not a problem for the current code, which uses
1421 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1422 * png_do_gray_to_rgb() transformation.
1423 *
1424 * TODO: this code needs to be revised to avoid the complexity and
1425 * interdependencies. The color type of the background should be recorded in
1426 * png_set_background, along with the bit depth, then the code has a record
1427 * of exactly what color space the background is currently in.
1428 */
1429 if (png_ptr->transformations & PNG_BACKGROUND_EXPAND)
1430 {
1431 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1432 * the file was grayscale the background value is gray.
1433 */
1434 if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
1435 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1436 }
1437
1438 else if (png_ptr->transformations & PNG_COMPOSE)
1439 {
1440 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1441 * so the color is in the color space of the output or png_set_alpha_mode
1442 * was called and the color is black. Ignore RGB_TO_GRAY because that
1443 * happens before GRAY_TO_RGB.
1444 */
1445 if (png_ptr->transformations & PNG_GRAY_TO_RGB)
1446 {
1447 if (png_ptr->background.red == png_ptr->background.green &&
1448 png_ptr->background.red == png_ptr->background.blue)
1449 {
1450 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1451 png_ptr->background.gray = png_ptr->background.red;
1452 }
1453 }
1454 }
1455 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
1456 #endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED */
1457
1458 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1459 * can be performed directly on the palette, and some (such as rgb to gray)
1460 * can be optimized inside the palette. This is particularly true of the
1461 * composite (background and alpha) stuff, which can be pretty much all done
1462 * in the palette even if the result is expanded to RGB or gray afterward.
1463 *
1464 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1465 * earlier and the palette stuff is actually handled on the first row. This
1466 * leads to the reported bug that the palette returned by png_get_PLTE is not
1467 * updated.
1468 */
1469 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1470 png_init_palette_transformations(png_ptr);
1471
1472 else
1473 png_init_rgb_transformations(png_ptr);
1474
1475 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1476 defined(PNG_READ_EXPAND_16_SUPPORTED)
1477 if ((png_ptr->transformations & PNG_EXPAND_16) &&
1478 (png_ptr->transformations & PNG_COMPOSE) &&
1479 !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1480 png_ptr->bit_depth != 16)
1481 {
1482 /* TODO: fix this. Because the expand_16 operation is after the compose
1483 * handling the background color must be 8, not 16, bits deep, but the
1484 * application will supply a 16-bit value so reduce it here.
1485 *
1486 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1487 * present, so that case is ok (until do_expand_16 is moved.)
1488 *
1489 * NOTE: this discards the low 16 bits of the user supplied background
1490 * color, but until expand_16 works properly there is no choice!
1491 */
1492 # define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
1493 CHOP(png_ptr->background.red);
1494 CHOP(png_ptr->background.green);
1495 CHOP(png_ptr->background.blue);
1496 CHOP(png_ptr->background.gray);
1497 # undef CHOP
1498 }
1499 #endif /* PNG_READ_BACKGROUND_SUPPORTED && PNG_READ_EXPAND_16_SUPPORTED */
1500
1501 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1502 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1503 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1504 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) &&
1505 (png_ptr->transformations & PNG_COMPOSE) &&
1506 !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1507 png_ptr->bit_depth == 16)
1508 {
1509 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1510 * component this will also happen after PNG_COMPOSE and so the background
1511 * color must be pre-expanded here.
1512 *
1513 * TODO: fix this too.
1514 */
1515 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
1516 png_ptr->background.green =
1517 (png_uint_16)(png_ptr->background.green * 257);
1518 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
1519 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
1520 }
1521 #endif
1522
1523 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1524 * background support (see the comments in scripts/pnglibconf.dfa), this
1525 * allows pre-multiplication of the alpha channel to be implemented as
1526 * compositing on black. This is probably sub-optimal and has been done in
1527 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1528 * implement the new API quickly, without lots of internal changes.)
1529 */
1530
1531 #ifdef PNG_READ_GAMMA_SUPPORTED
1532 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1533 /* Includes ALPHA_MODE */
1534 png_ptr->background_1 = png_ptr->background;
1535 # endif
1536
1537 /* This needs to change - in the palette image case a whole set of tables are
1538 * built when it would be quicker to just calculate the correct value for
1539 * each palette entry directly. Also, the test is too tricky - why check
1540 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1541 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1542 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1543 * the gamma tables will not be built even if composition is required on a
1544 * gamma encoded value.
1545 *
1546 * In 1.5.4 this is addressed below by an additional check on the individual
1547 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1548 * tables.
1549 */
1550 if ((png_ptr->transformations & PNG_GAMMA)
1551 || ((png_ptr->transformations & PNG_RGB_TO_GRAY)
1552 && (png_gamma_significant(png_ptr->colorspace.gamma) ||
1553 png_gamma_significant(png_ptr->screen_gamma)))
1554 || ((png_ptr->transformations & PNG_COMPOSE)
1555 && (png_gamma_significant(png_ptr->colorspace.gamma)
1556 || png_gamma_significant(png_ptr->screen_gamma)
1557 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1558 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE
1559 && png_gamma_significant(png_ptr->background_gamma))
1560 # endif
1561 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA)
1562 && png_gamma_significant(png_ptr->screen_gamma))
1563 )
1564 {
1565 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
1566
1567 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1568 if (png_ptr->transformations & PNG_COMPOSE)
1569 {
1570 /* Issue a warning about this combination: because RGB_TO_GRAY is
1571 * optimized to do the gamma transform if present yet do_background has
1572 * to do the same thing if both options are set a
1573 * double-gamma-correction happens. This is true in all versions of
1574 * libpng to date.
1575 */
1576 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
1577 png_warning(png_ptr,
1578 "libpng does not support gamma+background+rgb_to_gray");
1579
1580 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1581 {
1582 /* We don't get to here unless there is a tRNS chunk with non-opaque
1583 * entries - see the checking code at the start of this function.
1584 */
1585 png_color back, back_1;
1586 png_colorp palette = png_ptr->palette;
1587 int num_palette = png_ptr->num_palette;
1588 int i;
1589 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
1590 {
1591
1592 back.red = png_ptr->gamma_table[png_ptr->background.red];
1593 back.green = png_ptr->gamma_table[png_ptr->background.green];
1594 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
1595
1596 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
1597 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
1598 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
1599 }
1600 else
1601 {
1602 png_fixed_point g, gs;
1603
1604 switch (png_ptr->background_gamma_type)
1605 {
1606 case PNG_BACKGROUND_GAMMA_SCREEN:
1607 g = (png_ptr->screen_gamma);
1608 gs = PNG_FP_1;
1609 break;
1610
1611 case PNG_BACKGROUND_GAMMA_FILE:
1612 g = png_reciprocal(png_ptr->colorspace.gamma);
1613 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1614 png_ptr->screen_gamma);
1615 break;
1616
1617 case PNG_BACKGROUND_GAMMA_UNIQUE:
1618 g = png_reciprocal(png_ptr->background_gamma);
1619 gs = png_reciprocal2(png_ptr->background_gamma,
1620 png_ptr->screen_gamma);
1621 break;
1622 default:
1623 g = PNG_FP_1; /* back_1 */
1624 gs = PNG_FP_1; /* back */
1625 break;
1626 }
1627
1628 if (png_gamma_significant(gs))
1629 {
1630 back.red = png_gamma_8bit_correct(png_ptr->background.red,
1631 gs);
1632 back.green = png_gamma_8bit_correct(png_ptr->background.green,
1633 gs);
1634 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1635 gs);
1636 }
1637
1638 else
1639 {
1640 back.red = (png_byte)png_ptr->background.red;
1641 back.green = (png_byte)png_ptr->background.green;
1642 back.blue = (png_byte)png_ptr->background.blue;
1643 }
1644
1645 if (png_gamma_significant(g))
1646 {
1647 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
1648 g);
1649 back_1.green = png_gamma_8bit_correct(
1650 png_ptr->background.green, g);
1651 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1652 g);
1653 }
1654
1655 else
1656 {
1657 back_1.red = (png_byte)png_ptr->background.red;
1658 back_1.green = (png_byte)png_ptr->background.green;
1659 back_1.blue = (png_byte)png_ptr->background.blue;
1660 }
1661 }
1662
1663 for (i = 0; i < num_palette; i++)
1664 {
1665 if (i < (int)png_ptr->num_trans &&
1666 png_ptr->trans_alpha[i] != 0xff)
1667 {
1668 if (png_ptr->trans_alpha[i] == 0)
1669 {
1670 palette[i] = back;
1671 }
1672 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1673 {
1674 png_byte v, w;
1675
1676 v = png_ptr->gamma_to_1[palette[i].red];
1677 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
1678 palette[i].red = png_ptr->gamma_from_1[w];
1679
1680 v = png_ptr->gamma_to_1[palette[i].green];
1681 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
1682 palette[i].green = png_ptr->gamma_from_1[w];
1683
1684 v = png_ptr->gamma_to_1[palette[i].blue];
1685 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
1686 palette[i].blue = png_ptr->gamma_from_1[w];
1687 }
1688 }
1689 else
1690 {
1691 palette[i].red = png_ptr->gamma_table[palette[i].red];
1692 palette[i].green = png_ptr->gamma_table[palette[i].green];
1693 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1694 }
1695 }
1696
1697 /* Prevent the transformations being done again.
1698 *
1699 * NOTE: this is highly dubious; it removes the transformations in
1700 * place. This seems inconsistent with the general treatment of the
1701 * transformations elsewhere.
1702 */
1703 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
1704 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1705
1706 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1707 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1708 {
1709 int gs_sig, g_sig;
1710 png_fixed_point g = PNG_FP_1; /* Correction to linear */
1711 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
1712
1713 switch (png_ptr->background_gamma_type)
1714 {
1715 case PNG_BACKGROUND_GAMMA_SCREEN:
1716 g = png_ptr->screen_gamma;
1717 /* gs = PNG_FP_1; */
1718 break;
1719
1720 case PNG_BACKGROUND_GAMMA_FILE:
1721 g = png_reciprocal(png_ptr->colorspace.gamma);
1722 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1723 png_ptr->screen_gamma);
1724 break;
1725
1726 case PNG_BACKGROUND_GAMMA_UNIQUE:
1727 g = png_reciprocal(png_ptr->background_gamma);
1728 gs = png_reciprocal2(png_ptr->background_gamma,
1729 png_ptr->screen_gamma);
1730 break;
1731
1732 default:
1733 png_error(png_ptr, "invalid background gamma type");
1734 }
1735
1736 g_sig = png_gamma_significant(g);
1737 gs_sig = png_gamma_significant(gs);
1738
1739 if (g_sig)
1740 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
1741 png_ptr->background.gray, g);
1742
1743 if (gs_sig)
1744 png_ptr->background.gray = png_gamma_correct(png_ptr,
1745 png_ptr->background.gray, gs);
1746
1747 if ((png_ptr->background.red != png_ptr->background.green) ||
1748 (png_ptr->background.red != png_ptr->background.blue) ||
1749 (png_ptr->background.red != png_ptr->background.gray))
1750 {
1751 /* RGB or RGBA with color background */
1752 if (g_sig)
1753 {
1754 png_ptr->background_1.red = png_gamma_correct(png_ptr,
1755 png_ptr->background.red, g);
1756
1757 png_ptr->background_1.green = png_gamma_correct(png_ptr,
1758 png_ptr->background.green, g);
1759
1760 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
1761 png_ptr->background.blue, g);
1762 }
1763
1764 if (gs_sig)
1765 {
1766 png_ptr->background.red = png_gamma_correct(png_ptr,
1767 png_ptr->background.red, gs);
1768
1769 png_ptr->background.green = png_gamma_correct(png_ptr,
1770 png_ptr->background.green, gs);
1771
1772 png_ptr->background.blue = png_gamma_correct(png_ptr,
1773 png_ptr->background.blue, gs);
1774 }
1775 }
1776
1777 else
1778 {
1779 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1780 png_ptr->background_1.red = png_ptr->background_1.green
1781 = png_ptr->background_1.blue = png_ptr->background_1.gray;
1782
1783 png_ptr->background.red = png_ptr->background.green
1784 = png_ptr->background.blue = png_ptr->background.gray;
1785 }
1786
1787 /* The background is now in screen gamma: */
1788 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
1789 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1790 }/* png_ptr->transformations & PNG_BACKGROUND */
1791
1792 else
1793 /* Transformation does not include PNG_BACKGROUND */
1794 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
1795 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
1796 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1797 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1798 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
1799 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
1800 #endif
1801 )
1802 {
1803 png_colorp palette = png_ptr->palette;
1804 int num_palette = png_ptr->num_palette;
1805 int i;
1806
1807 /* NOTE: there are other transformations that should probably be in
1808 * here too.
1809 */
1810 for (i = 0; i < num_palette; i++)
1811 {
1812 palette[i].red = png_ptr->gamma_table[palette[i].red];
1813 palette[i].green = png_ptr->gamma_table[palette[i].green];
1814 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1815 }
1816
1817 /* Done the gamma correction. */
1818 png_ptr->transformations &= ~PNG_GAMMA;
1819 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1820 }
1821 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1822 else
1823 #endif
1824 #endif /* PNG_READ_GAMMA_SUPPORTED */
1825
1826 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1827 /* No GAMMA transformation (see the hanging else 4 lines above) */
1828 if ((png_ptr->transformations & PNG_COMPOSE) &&
1829 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1830 {
1831 int i;
1832 int istop = (int)png_ptr->num_trans;
1833 png_color back;
1834 png_colorp palette = png_ptr->palette;
1835
1836 back.red = (png_byte)png_ptr->background.red;
1837 back.green = (png_byte)png_ptr->background.green;
1838 back.blue = (png_byte)png_ptr->background.blue;
1839
1840 for (i = 0; i < istop; i++)
1841 {
1842 if (png_ptr->trans_alpha[i] == 0)
1843 {
1844 palette[i] = back;
1845 }
1846
1847 else if (png_ptr->trans_alpha[i] != 0xff)
1848 {
1849 /* The png_composite() macro is defined in png.h */
1850 png_composite(palette[i].red, palette[i].red,
1851 png_ptr->trans_alpha[i], back.red);
1852
1853 png_composite(palette[i].green, palette[i].green,
1854 png_ptr->trans_alpha[i], back.green);
1855
1856 png_composite(palette[i].blue, palette[i].blue,
1857 png_ptr->trans_alpha[i], back.blue);
1858 }
1859 }
1860
1861 png_ptr->transformations &= ~PNG_COMPOSE;
1862
1863 //png_ptr->flags |= PNG_FLAG_STRIP_ALPHA; /* Add by Sunliang.Liu */
1864 }
1865 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
1866
1867 #ifdef PNG_READ_SHIFT_SUPPORTED
1868 if ((png_ptr->transformations & PNG_SHIFT) &&
1869 !(png_ptr->transformations & PNG_EXPAND) &&
1870 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1871 {
1872 int i;
1873 int istop = png_ptr->num_palette;
1874 int shift = 8 - png_ptr->sig_bit.red;
1875
1876 png_ptr->transformations &= ~PNG_SHIFT;
1877
1878 /* significant bits can be in the range 1 to 7 for a meaninful result, if
1879 * the number of significant bits is 0 then no shift is done (this is an
1880 * error condition which is silently ignored.)
1881 */
1882 if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
1883 {
1884 int component = png_ptr->palette[i].red;
1885
1886 component >>= shift;
1887 png_ptr->palette[i].red = (png_byte)component;
1888 }
1889
1890 shift = 8 - png_ptr->sig_bit.green;
1891 if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
1892 {
1893 int component = png_ptr->palette[i].green;
1894
1895 component >>= shift;
1896 png_ptr->palette[i].green = (png_byte)component;
1897 }
1898
1899 shift = 8 - png_ptr->sig_bit.blue;
1900 if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
1901 {
1902 int component = png_ptr->palette[i].blue;
1903
1904 component >>= shift;
1905 png_ptr->palette[i].blue = (png_byte)component;
1906 }
1907 }
1908 #endif /* PNG_READ_SHIFT_SUPPORTED */
1909 }
1910
1911 /* Modify the info structure to reflect the transformations. The
1912 * info should be updated so a PNG file could be written with it,
1913 * assuming the transformations result in valid PNG data.
1914 */
1915 void /* PRIVATE */
png_read_transform_info(png_structrp png_ptr,png_inforp info_ptr)1916 png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
1917 {
1918 png_debug(1, "in png_read_transform_info");
1919
1920 #ifdef PNG_READ_EXPAND_SUPPORTED
1921 if (png_ptr->transformations & PNG_EXPAND)
1922 {
1923 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1924 {
1925 /* This check must match what actually happens in
1926 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1927 * it is all opaque we must do the same (at present it does not.)
1928 */
1929 if (png_ptr->num_trans > 0)
1930 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
1931
1932 else
1933 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
1934
1935 info_ptr->bit_depth = 8;
1936 info_ptr->num_trans = 0;
1937 }
1938 else
1939 {
1940 if (png_ptr->num_trans)
1941 {
1942 if (png_ptr->transformations & PNG_EXPAND_tRNS)
1943 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
1944 }
1945 if (info_ptr->bit_depth < 8)
1946 info_ptr->bit_depth = 8;
1947
1948 info_ptr->num_trans = 0;
1949 }
1950 }
1951 #endif
1952
1953 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
1954 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1955 /* The following is almost certainly wrong unless the background value is in
1956 * the screen space!
1957 */
1958 if (png_ptr->transformations & PNG_COMPOSE)
1959 info_ptr->background = png_ptr->background;
1960 #endif
1961
1962 #ifdef PNG_READ_GAMMA_SUPPORTED
1963 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
1964 * however it seems that the code in png_init_read_transformations, which has
1965 * been called before this from png_read_update_info->png_read_start_row
1966 * sometimes does the gamma transform and cancels the flag.
1967 *
1968 * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
1969 * the screen_gamma value. The following probably results in weirdness if
1970 * the info_ptr is used by the app after the rows have been read.
1971 */
1972 info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
1973 #endif
1974
1975 if (info_ptr->bit_depth == 16)
1976 {
1977 # ifdef PNG_READ_16BIT_SUPPORTED
1978 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1979 if (png_ptr->transformations & PNG_SCALE_16_TO_8)
1980 info_ptr->bit_depth = 8;
1981 # endif
1982
1983 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1984 if (png_ptr->transformations & PNG_16_TO_8)
1985 info_ptr->bit_depth = 8;
1986 # endif
1987
1988 # else
1989 /* No 16 bit support: force chopping 16-bit input down to 8, in this case
1990 * the app program can chose if both APIs are available by setting the
1991 * correct scaling to use.
1992 */
1993 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1994 /* For compatibility with previous versions use the strip method by
1995 * default. This code works because if PNG_SCALE_16_TO_8 is already
1996 * set the code below will do that in preference to the chop.
1997 */
1998 png_ptr->transformations |= PNG_16_TO_8;
1999 info_ptr->bit_depth = 8;
2000 # else
2001
2002 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2003 png_ptr->transformations |= PNG_SCALE_16_TO_8;
2004 info_ptr->bit_depth = 8;
2005 # else
2006
2007 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
2008 # endif
2009 # endif
2010 #endif /* !READ_16BIT_SUPPORTED */
2011 }
2012
2013 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2014 if (png_ptr->transformations & PNG_GRAY_TO_RGB)
2015 info_ptr->color_type = (png_byte)(info_ptr->color_type |
2016 PNG_COLOR_MASK_COLOR);
2017 #endif
2018
2019 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2020 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
2021 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2022 ~PNG_COLOR_MASK_COLOR);
2023 #endif
2024
2025 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2026 if (png_ptr->transformations & PNG_QUANTIZE)
2027 {
2028 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2029 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
2030 png_ptr->palette_lookup && info_ptr->bit_depth == 8)
2031 {
2032 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
2033 }
2034 }
2035 #endif
2036
2037 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2038 if (png_ptr->transformations & PNG_EXPAND_16 && info_ptr->bit_depth == 8 &&
2039 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
2040 {
2041 info_ptr->bit_depth = 16;
2042 }
2043 #endif
2044
2045 #ifdef PNG_READ_PACK_SUPPORTED
2046 if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8))
2047 info_ptr->bit_depth = 8;
2048 #endif
2049
2050 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
2051 info_ptr->channels = 1;
2052
2053 else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
2054 info_ptr->channels = 3;
2055
2056 else
2057 info_ptr->channels = 1;
2058
2059 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2060 if (png_ptr->transformations & PNG_STRIP_ALPHA)
2061 {
2062 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2063 ~PNG_COLOR_MASK_ALPHA);
2064 info_ptr->num_trans = 0;
2065 }
2066 #endif
2067
2068 if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
2069 info_ptr->channels++;
2070
2071 #ifdef PNG_READ_FILLER_SUPPORTED
2072 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2073 if ((png_ptr->transformations & PNG_FILLER) &&
2074 ((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2075 (info_ptr->color_type == PNG_COLOR_TYPE_GRAY)))
2076 {
2077 info_ptr->channels++;
2078 /* If adding a true alpha channel not just filler */
2079 if (png_ptr->transformations & PNG_ADD_ALPHA)
2080 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
2081 }
2082 #endif
2083
2084 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2085 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2086 if (png_ptr->transformations & PNG_USER_TRANSFORM)
2087 {
2088 if (info_ptr->bit_depth < png_ptr->user_transform_depth)
2089 info_ptr->bit_depth = png_ptr->user_transform_depth;
2090
2091 if (info_ptr->channels < png_ptr->user_transform_channels)
2092 info_ptr->channels = png_ptr->user_transform_channels;
2093 }
2094 #endif
2095
2096 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
2097 info_ptr->bit_depth);
2098
2099 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
2100
2101 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2102 * check in png_rowbytes that the user buffer won't get overwritten. Note
2103 * that the field is not always set - if png_read_update_info isn't called
2104 * the application has to either not do any transforms or get the calculation
2105 * right itself.
2106 */
2107 png_ptr->info_rowbytes = info_ptr->rowbytes;
2108
2109 #ifndef PNG_READ_EXPAND_SUPPORTED
2110 if (png_ptr)
2111 return;
2112 #endif
2113 }
2114
2115 /* Transform the row. The order of transformations is significant,
2116 * and is very touchy. If you add a transformation, take care to
2117 * decide how it fits in with the other transformations here.
2118 */
2119 void /* PRIVATE */
png_do_read_transformations(png_structrp png_ptr,png_row_infop row_info)2120 png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
2121 {
2122 png_debug(1, "in png_do_read_transformations");
2123
2124 if (png_ptr->row_buf == NULL)
2125 {
2126 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
2127 * error is incredibly rare and incredibly easy to debug without this
2128 * information.
2129 */
2130 png_error(png_ptr, "NULL row buffer");
2131 }
2132
2133 /* The following is debugging; prior to 1.5.4 the code was never compiled in;
2134 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
2135 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for
2136 * all transformations, however in practice the ROW_INIT always gets done on
2137 * demand, if necessary.
2138 */
2139 if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
2140 !(png_ptr->flags & PNG_FLAG_ROW_INIT))
2141 {
2142 /* Application has failed to call either png_read_start_image() or
2143 * png_read_update_info() after setting transforms that expand pixels.
2144 * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
2145 */
2146 png_error(png_ptr, "Uninitialized row");
2147 }
2148
2149 #ifdef PNG_READ_EXPAND_SUPPORTED
2150 if (png_ptr->transformations & PNG_EXPAND)
2151 {
2152 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
2153 {
2154 png_do_expand_palette(row_info, png_ptr->row_buf + 1,
2155 png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
2156 }
2157
2158 else
2159 {
2160 if (png_ptr->num_trans &&
2161 (png_ptr->transformations & PNG_EXPAND_tRNS))
2162 png_do_expand(row_info, png_ptr->row_buf + 1,
2163 &(png_ptr->trans_color));
2164
2165 else
2166 png_do_expand(row_info, png_ptr->row_buf + 1,
2167 NULL);
2168 }
2169 }
2170 #endif
2171
2172 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2173 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
2174 !(png_ptr->transformations & PNG_COMPOSE) &&
2175 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2176 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
2177 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
2178 0 /* at_start == false, because SWAP_ALPHA happens later */);
2179 #endif
2180
2181 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2182 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
2183 {
2184 int rgb_error =
2185 png_do_rgb_to_gray(png_ptr, row_info,
2186 png_ptr->row_buf + 1);
2187
2188 if (rgb_error)
2189 {
2190 png_ptr->rgb_to_gray_status=1;
2191 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
2192 PNG_RGB_TO_GRAY_WARN)
2193 png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
2194
2195 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
2196 PNG_RGB_TO_GRAY_ERR)
2197 png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
2198 }
2199 }
2200 #endif
2201
2202 /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
2203 *
2204 * In most cases, the "simple transparency" should be done prior to doing
2205 * gray-to-RGB, or you will have to test 3x as many bytes to check if a
2206 * pixel is transparent. You would also need to make sure that the
2207 * transparency information is upgraded to RGB.
2208 *
2209 * To summarize, the current flow is:
2210 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
2211 * with background "in place" if transparent,
2212 * convert to RGB if necessary
2213 * - Gray + alpha -> composite with gray background and remove alpha bytes,
2214 * convert to RGB if necessary
2215 *
2216 * To support RGB backgrounds for gray images we need:
2217 * - Gray + simple transparency -> convert to RGB + simple transparency,
2218 * compare 3 or 6 bytes and composite with
2219 * background "in place" if transparent
2220 * (3x compare/pixel compared to doing
2221 * composite with gray bkgrnd)
2222 * - Gray + alpha -> convert to RGB + alpha, composite with background and
2223 * remove alpha bytes (3x float
2224 * operations/pixel compared with composite
2225 * on gray background)
2226 *
2227 * Greg's change will do this. The reason it wasn't done before is for
2228 * performance, as this increases the per-pixel operations. If we would check
2229 * in advance if the background was gray or RGB, and position the gray-to-RGB
2230 * transform appropriately, then it would save a lot of work/time.
2231 */
2232
2233 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2234 /* If gray -> RGB, do so now only if background is non-gray; else do later
2235 * for performance reasons
2236 */
2237 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
2238 !(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
2239 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
2240 #endif
2241
2242 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
2243 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
2244 if (png_ptr->transformations & PNG_COMPOSE)
2245 png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
2246 #endif
2247
2248 #ifdef PNG_READ_GAMMA_SUPPORTED
2249 if ((png_ptr->transformations & PNG_GAMMA) &&
2250 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2251 /* Because RGB_TO_GRAY does the gamma transform. */
2252 !(png_ptr->transformations & PNG_RGB_TO_GRAY) &&
2253 #endif
2254 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
2255 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
2256 /* Because PNG_COMPOSE does the gamma transform if there is something to
2257 * do (if there is an alpha channel or transparency.)
2258 */
2259 !((png_ptr->transformations & PNG_COMPOSE) &&
2260 ((png_ptr->num_trans != 0) ||
2261 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) &&
2262 #endif
2263 /* Because png_init_read_transformations transforms the palette, unless
2264 * RGB_TO_GRAY will do the transform.
2265 */
2266 (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
2267 png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
2268 #endif
2269
2270 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2271 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
2272 (png_ptr->transformations & PNG_COMPOSE) &&
2273 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2274 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
2275 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
2276 0 /* at_start == false, because SWAP_ALPHA happens later */);
2277 #endif
2278
2279 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
2280 if ((png_ptr->transformations & PNG_ENCODE_ALPHA) &&
2281 (row_info->color_type & PNG_COLOR_MASK_ALPHA))
2282 png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
2283 #endif
2284
2285 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2286 if (png_ptr->transformations & PNG_SCALE_16_TO_8)
2287 png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
2288 #endif
2289
2290 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2291 /* There is no harm in doing both of these because only one has any effect,
2292 * by putting the 'scale' option first if the app asks for scale (either by
2293 * calling the API or in a TRANSFORM flag) this is what happens.
2294 */
2295 if (png_ptr->transformations & PNG_16_TO_8)
2296 png_do_chop(row_info, png_ptr->row_buf + 1);
2297 #endif
2298
2299 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2300 if (png_ptr->transformations & PNG_QUANTIZE)
2301 {
2302 png_do_quantize(row_info, png_ptr->row_buf + 1,
2303 png_ptr->palette_lookup, png_ptr->quantize_index);
2304
2305 if (row_info->rowbytes == 0)
2306 png_error(png_ptr, "png_do_quantize returned rowbytes=0");
2307 }
2308 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
2309
2310 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2311 /* Do the expansion now, after all the arithmetic has been done. Notice
2312 * that previous transformations can handle the PNG_EXPAND_16 flag if this
2313 * is efficient (particularly true in the case of gamma correction, where
2314 * better accuracy results faster!)
2315 */
2316 if (png_ptr->transformations & PNG_EXPAND_16)
2317 png_do_expand_16(row_info, png_ptr->row_buf + 1);
2318 #endif
2319
2320 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2321 /* NOTE: moved here in 1.5.4 (from much later in this list.) */
2322 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
2323 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
2324 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
2325 #endif
2326
2327 #ifdef PNG_READ_INVERT_SUPPORTED
2328 if (png_ptr->transformations & PNG_INVERT_MONO)
2329 png_do_invert(row_info, png_ptr->row_buf + 1);
2330 #endif
2331
2332 #ifdef PNG_READ_SHIFT_SUPPORTED
2333 if (png_ptr->transformations & PNG_SHIFT)
2334 png_do_unshift(row_info, png_ptr->row_buf + 1,
2335 &(png_ptr->shift));
2336 #endif
2337
2338 #ifdef PNG_READ_PACK_SUPPORTED
2339 if (png_ptr->transformations & PNG_PACK)
2340 png_do_unpack(row_info, png_ptr->row_buf + 1);
2341 #endif
2342
2343 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
2344 /* Added at libpng-1.5.10 */
2345 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
2346 png_ptr->num_palette_max >= 0)
2347 png_do_check_palette_indexes(png_ptr, row_info);
2348 #endif
2349
2350 #ifdef PNG_READ_BGR_SUPPORTED
2351 if (png_ptr->transformations & PNG_BGR)
2352 png_do_bgr(row_info, png_ptr->row_buf + 1);
2353 #endif
2354
2355 #ifdef PNG_READ_PACKSWAP_SUPPORTED
2356 if (png_ptr->transformations & PNG_PACKSWAP)
2357 png_do_packswap(row_info, png_ptr->row_buf + 1);
2358 #endif
2359
2360 #ifdef PNG_READ_FILLER_SUPPORTED
2361 if (png_ptr->transformations & PNG_FILLER)
2362 png_do_read_filler(row_info, png_ptr->row_buf + 1,
2363 (png_uint_32)png_ptr->filler, png_ptr->flags);
2364 #endif
2365
2366 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2367 if (png_ptr->transformations & PNG_INVERT_ALPHA)
2368 png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
2369 #endif
2370
2371 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2372 if (png_ptr->transformations & PNG_SWAP_ALPHA)
2373 png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
2374 #endif
2375
2376 #ifdef PNG_READ_16BIT_SUPPORTED
2377 #ifdef PNG_READ_SWAP_SUPPORTED
2378 if (png_ptr->transformations & PNG_SWAP_BYTES)
2379 png_do_swap(row_info, png_ptr->row_buf + 1);
2380 #endif
2381 #endif
2382
2383 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
2384 if (png_ptr->transformations & PNG_USER_TRANSFORM)
2385 {
2386 if (png_ptr->read_user_transform_fn != NULL)
2387 (*(png_ptr->read_user_transform_fn)) /* User read transform function */
2388 (png_ptr, /* png_ptr */
2389 row_info, /* row_info: */
2390 /* png_uint_32 width; width of row */
2391 /* png_size_t rowbytes; number of bytes in row */
2392 /* png_byte color_type; color type of pixels */
2393 /* png_byte bit_depth; bit depth of samples */
2394 /* png_byte channels; number of channels (1-4) */
2395 /* png_byte pixel_depth; bits per pixel (depth*channels) */
2396 png_ptr->row_buf + 1); /* start of pixel data for row */
2397 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
2398 if (png_ptr->user_transform_depth)
2399 row_info->bit_depth = png_ptr->user_transform_depth;
2400
2401 if (png_ptr->user_transform_channels)
2402 row_info->channels = png_ptr->user_transform_channels;
2403 #endif
2404 row_info->pixel_depth = (png_byte)(row_info->bit_depth *
2405 row_info->channels);
2406
2407 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
2408 }
2409 #endif
2410 }
2411
2412 #ifdef PNG_READ_PACK_SUPPORTED
2413 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2414 * without changing the actual values. Thus, if you had a row with
2415 * a bit depth of 1, you would end up with bytes that only contained
2416 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2417 * png_do_shift() after this.
2418 */
2419 void /* PRIVATE */
png_do_unpack(png_row_infop row_info,png_bytep row)2420 png_do_unpack(png_row_infop row_info, png_bytep row)
2421 {
2422 png_debug(1, "in png_do_unpack");
2423
2424 if (row_info->bit_depth < 8)
2425 {
2426 png_uint_32 i;
2427 png_uint_32 row_width=row_info->width;
2428
2429 switch (row_info->bit_depth)
2430 {
2431 case 1:
2432 {
2433 png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
2434 png_bytep dp = row + (png_size_t)row_width - 1;
2435 png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
2436 for (i = 0; i < row_width; i++)
2437 {
2438 *dp = (png_byte)((*sp >> shift) & 0x01);
2439
2440 if (shift == 7)
2441 {
2442 shift = 0;
2443 sp--;
2444 }
2445
2446 else
2447 shift++;
2448
2449 dp--;
2450 }
2451 break;
2452 }
2453
2454 case 2:
2455 {
2456
2457 png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
2458 png_bytep dp = row + (png_size_t)row_width - 1;
2459 png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
2460 for (i = 0; i < row_width; i++)
2461 {
2462 *dp = (png_byte)((*sp >> shift) & 0x03);
2463
2464 if (shift == 6)
2465 {
2466 shift = 0;
2467 sp--;
2468 }
2469
2470 else
2471 shift += 2;
2472
2473 dp--;
2474 }
2475 break;
2476 }
2477
2478 case 4:
2479 {
2480 png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
2481 png_bytep dp = row + (png_size_t)row_width - 1;
2482 png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
2483 for (i = 0; i < row_width; i++)
2484 {
2485 *dp = (png_byte)((*sp >> shift) & 0x0f);
2486
2487 if (shift == 4)
2488 {
2489 shift = 0;
2490 sp--;
2491 }
2492
2493 else
2494 shift = 4;
2495
2496 dp--;
2497 }
2498 break;
2499 }
2500
2501 default:
2502 break;
2503 }
2504 row_info->bit_depth = 8;
2505 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2506 row_info->rowbytes = row_width * row_info->channels;
2507 }
2508 }
2509 #endif
2510
2511 #ifdef PNG_READ_SHIFT_SUPPORTED
2512 /* Reverse the effects of png_do_shift. This routine merely shifts the
2513 * pixels back to their significant bits values. Thus, if you have
2514 * a row of bit depth 8, but only 5 are significant, this will shift
2515 * the values back to 0 through 31.
2516 */
2517 void /* PRIVATE */
png_do_unshift(png_row_infop row_info,png_bytep row,png_const_color_8p sig_bits)2518 png_do_unshift(png_row_infop row_info, png_bytep row,
2519 png_const_color_8p sig_bits)
2520 {
2521 int color_type;
2522
2523 png_debug(1, "in png_do_unshift");
2524
2525 /* The palette case has already been handled in the _init routine. */
2526 color_type = row_info->color_type;
2527
2528 if (color_type != PNG_COLOR_TYPE_PALETTE)
2529 {
2530 int shift[4];
2531 int channels = 0;
2532 int bit_depth = row_info->bit_depth;
2533
2534 if (color_type & PNG_COLOR_MASK_COLOR)
2535 {
2536 shift[channels++] = bit_depth - sig_bits->red;
2537 shift[channels++] = bit_depth - sig_bits->green;
2538 shift[channels++] = bit_depth - sig_bits->blue;
2539 }
2540
2541 else
2542 {
2543 shift[channels++] = bit_depth - sig_bits->gray;
2544 }
2545
2546 if (color_type & PNG_COLOR_MASK_ALPHA)
2547 {
2548 shift[channels++] = bit_depth - sig_bits->alpha;
2549 }
2550
2551 {
2552 int c, have_shift;
2553
2554 for (c = have_shift = 0; c < channels; ++c)
2555 {
2556 /* A shift of more than the bit depth is an error condition but it
2557 * gets ignored here.
2558 */
2559 if (shift[c] <= 0 || shift[c] >= bit_depth)
2560 shift[c] = 0;
2561
2562 else
2563 have_shift = 1;
2564 }
2565
2566 if (!have_shift)
2567 return;
2568 }
2569
2570 switch (bit_depth)
2571 {
2572 default:
2573 /* Must be 1bpp gray: should not be here! */
2574 /* NOTREACHED */
2575 break;
2576
2577 case 2:
2578 /* Must be 2bpp gray */
2579 /* assert(channels == 1 && shift[0] == 1) */
2580 {
2581 png_bytep bp = row;
2582 png_bytep bp_end = bp + row_info->rowbytes;
2583
2584 while (bp < bp_end)
2585 {
2586 int b = (*bp >> 1) & 0x55;
2587 *bp++ = (png_byte)b;
2588 }
2589 break;
2590 }
2591
2592 case 4:
2593 /* Must be 4bpp gray */
2594 /* assert(channels == 1) */
2595 {
2596 png_bytep bp = row;
2597 png_bytep bp_end = bp + row_info->rowbytes;
2598 int gray_shift = shift[0];
2599 int mask = 0xf >> gray_shift;
2600
2601 mask |= mask << 4;
2602
2603 while (bp < bp_end)
2604 {
2605 int b = (*bp >> gray_shift) & mask;
2606 *bp++ = (png_byte)b;
2607 }
2608 break;
2609 }
2610
2611 case 8:
2612 /* Single byte components, G, GA, RGB, RGBA */
2613 {
2614 png_bytep bp = row;
2615 png_bytep bp_end = bp + row_info->rowbytes;
2616 int channel = 0;
2617
2618 while (bp < bp_end)
2619 {
2620 int b = *bp >> shift[channel];
2621 if (++channel >= channels)
2622 channel = 0;
2623 *bp++ = (png_byte)b;
2624 }
2625 break;
2626 }
2627
2628 #ifdef PNG_READ_16BIT_SUPPORTED
2629 case 16:
2630 /* Double byte components, G, GA, RGB, RGBA */
2631 {
2632 png_bytep bp = row;
2633 png_bytep bp_end = bp + row_info->rowbytes;
2634 int channel = 0;
2635
2636 while (bp < bp_end)
2637 {
2638 int value = (bp[0] << 8) + bp[1];
2639
2640 value >>= shift[channel];
2641 if (++channel >= channels)
2642 channel = 0;
2643 *bp++ = (png_byte)(value >> 8);
2644 *bp++ = (png_byte)(value & 0xff);
2645 }
2646 break;
2647 }
2648 #endif
2649 }
2650 }
2651 }
2652 #endif
2653
2654 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2655 /* Scale rows of bit depth 16 down to 8 accurately */
2656 void /* PRIVATE */
png_do_scale_16_to_8(png_row_infop row_info,png_bytep row)2657 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
2658 {
2659 png_debug(1, "in png_do_scale_16_to_8");
2660
2661 if (row_info->bit_depth == 16)
2662 {
2663 png_bytep sp = row; /* source */
2664 png_bytep dp = row; /* destination */
2665 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2666
2667 while (sp < ep)
2668 {
2669 /* The input is an array of 16 bit components, these must be scaled to
2670 * 8 bits each. For a 16 bit value V the required value (from the PNG
2671 * specification) is:
2672 *
2673 * (V * 255) / 65535
2674 *
2675 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2676 *
2677 * Represent V as the two byte value vhi.vlo. Make a guess that the
2678 * result is the top byte of V, vhi, then the correction to this value
2679 * is:
2680 *
2681 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2682 * = floor(((vlo-vhi) + 128.5) / 257)
2683 *
2684 * This can be approximated using integer arithmetic (and a signed
2685 * shift):
2686 *
2687 * error = (vlo-vhi+128) >> 8;
2688 *
2689 * The approximate differs from the exact answer only when (vlo-vhi) is
2690 * 128; it then gives a correction of +1 when the exact correction is
2691 * 0. This gives 128 errors. The exact answer (correct for all 16 bit
2692 * input values) is:
2693 *
2694 * error = (vlo-vhi+128)*65535 >> 24;
2695 *
2696 * An alternative arithmetic calculation which also gives no errors is:
2697 *
2698 * (V * 255 + 32895) >> 16
2699 */
2700
2701 png_int_32 tmp = *sp++; /* must be signed! */
2702 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
2703 *dp++ = (png_byte)tmp;
2704 }
2705
2706 row_info->bit_depth = 8;
2707 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2708 row_info->rowbytes = row_info->width * row_info->channels;
2709 }
2710 }
2711 #endif
2712
2713 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2714 void /* PRIVATE */
2715 /* Simply discard the low byte. This was the default behavior prior
2716 * to libpng-1.5.4.
2717 */
png_do_chop(png_row_infop row_info,png_bytep row)2718 png_do_chop(png_row_infop row_info, png_bytep row)
2719 {
2720 png_debug(1, "in png_do_chop");
2721
2722 if (row_info->bit_depth == 16)
2723 {
2724 png_bytep sp = row; /* source */
2725 png_bytep dp = row; /* destination */
2726 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2727
2728 while (sp < ep)
2729 {
2730 *dp++ = *sp;
2731 sp += 2; /* skip low byte */
2732 }
2733
2734 row_info->bit_depth = 8;
2735 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2736 row_info->rowbytes = row_info->width * row_info->channels;
2737 }
2738 }
2739 #endif
2740
2741 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2742 void /* PRIVATE */
png_do_read_swap_alpha(png_row_infop row_info,png_bytep row)2743 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
2744 {
2745 png_debug(1, "in png_do_read_swap_alpha");
2746
2747 {
2748 png_uint_32 row_width = row_info->width;
2749 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2750 {
2751 /* This converts from RGBA to ARGB */
2752 if (row_info->bit_depth == 8)
2753 {
2754 png_bytep sp = row + row_info->rowbytes;
2755 png_bytep dp = sp;
2756 png_byte save;
2757 png_uint_32 i;
2758
2759 for (i = 0; i < row_width; i++)
2760 {
2761 save = *(--sp);
2762 *(--dp) = *(--sp);
2763 *(--dp) = *(--sp);
2764 *(--dp) = *(--sp);
2765 *(--dp) = save;
2766 }
2767 }
2768
2769 #ifdef PNG_READ_16BIT_SUPPORTED
2770 /* This converts from RRGGBBAA to AARRGGBB */
2771 else
2772 {
2773 png_bytep sp = row + row_info->rowbytes;
2774 png_bytep dp = sp;
2775 png_byte save[2];
2776 png_uint_32 i;
2777
2778 for (i = 0; i < row_width; i++)
2779 {
2780 save[0] = *(--sp);
2781 save[1] = *(--sp);
2782 *(--dp) = *(--sp);
2783 *(--dp) = *(--sp);
2784 *(--dp) = *(--sp);
2785 *(--dp) = *(--sp);
2786 *(--dp) = *(--sp);
2787 *(--dp) = *(--sp);
2788 *(--dp) = save[0];
2789 *(--dp) = save[1];
2790 }
2791 }
2792 #endif
2793 }
2794
2795 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2796 {
2797 /* This converts from GA to AG */
2798 if (row_info->bit_depth == 8)
2799 {
2800 png_bytep sp = row + row_info->rowbytes;
2801 png_bytep dp = sp;
2802 png_byte save;
2803 png_uint_32 i;
2804
2805 for (i = 0; i < row_width; i++)
2806 {
2807 save = *(--sp);
2808 *(--dp) = *(--sp);
2809 *(--dp) = save;
2810 }
2811 }
2812
2813 #ifdef PNG_READ_16BIT_SUPPORTED
2814 /* This converts from GGAA to AAGG */
2815 else
2816 {
2817 png_bytep sp = row + row_info->rowbytes;
2818 png_bytep dp = sp;
2819 png_byte save[2];
2820 png_uint_32 i;
2821
2822 for (i = 0; i < row_width; i++)
2823 {
2824 save[0] = *(--sp);
2825 save[1] = *(--sp);
2826 *(--dp) = *(--sp);
2827 *(--dp) = *(--sp);
2828 *(--dp) = save[0];
2829 *(--dp) = save[1];
2830 }
2831 }
2832 #endif
2833 }
2834 }
2835 }
2836 #endif
2837
2838 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2839 void /* PRIVATE */
png_do_read_invert_alpha(png_row_infop row_info,png_bytep row)2840 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
2841 {
2842 png_uint_32 row_width;
2843 png_debug(1, "in png_do_read_invert_alpha");
2844
2845 row_width = row_info->width;
2846 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2847 {
2848 if (row_info->bit_depth == 8)
2849 {
2850 /* This inverts the alpha channel in RGBA */
2851 png_bytep sp = row + row_info->rowbytes;
2852 png_bytep dp = sp;
2853 png_uint_32 i;
2854
2855 for (i = 0; i < row_width; i++)
2856 {
2857 *(--dp) = (png_byte)(255 - *(--sp));
2858
2859 /* This does nothing:
2860 *(--dp) = *(--sp);
2861 *(--dp) = *(--sp);
2862 *(--dp) = *(--sp);
2863 We can replace it with:
2864 */
2865 sp-=3;
2866 dp=sp;
2867 }
2868 }
2869
2870 #ifdef PNG_READ_16BIT_SUPPORTED
2871 /* This inverts the alpha channel in RRGGBBAA */
2872 else
2873 {
2874 png_bytep sp = row + row_info->rowbytes;
2875 png_bytep dp = sp;
2876 png_uint_32 i;
2877
2878 for (i = 0; i < row_width; i++)
2879 {
2880 *(--dp) = (png_byte)(255 - *(--sp));
2881 *(--dp) = (png_byte)(255 - *(--sp));
2882
2883 /* This does nothing:
2884 *(--dp) = *(--sp);
2885 *(--dp) = *(--sp);
2886 *(--dp) = *(--sp);
2887 *(--dp) = *(--sp);
2888 *(--dp) = *(--sp);
2889 *(--dp) = *(--sp);
2890 We can replace it with:
2891 */
2892 sp-=6;
2893 dp=sp;
2894 }
2895 }
2896 #endif
2897 }
2898 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2899 {
2900 if (row_info->bit_depth == 8)
2901 {
2902 /* This inverts the alpha channel in GA */
2903 png_bytep sp = row + row_info->rowbytes;
2904 png_bytep dp = sp;
2905 png_uint_32 i;
2906
2907 for (i = 0; i < row_width; i++)
2908 {
2909 *(--dp) = (png_byte)(255 - *(--sp));
2910 *(--dp) = *(--sp);
2911 }
2912 }
2913
2914 #ifdef PNG_READ_16BIT_SUPPORTED
2915 else
2916 {
2917 /* This inverts the alpha channel in GGAA */
2918 png_bytep sp = row + row_info->rowbytes;
2919 png_bytep dp = sp;
2920 png_uint_32 i;
2921
2922 for (i = 0; i < row_width; i++)
2923 {
2924 *(--dp) = (png_byte)(255 - *(--sp));
2925 *(--dp) = (png_byte)(255 - *(--sp));
2926 /*
2927 *(--dp) = *(--sp);
2928 *(--dp) = *(--sp);
2929 */
2930 sp-=2;
2931 dp=sp;
2932 }
2933 }
2934 #endif
2935 }
2936 }
2937 #endif
2938
2939 #ifdef PNG_READ_FILLER_SUPPORTED
2940 /* Add filler channel if we have RGB color */
2941 void /* PRIVATE */
png_do_read_filler(png_row_infop row_info,png_bytep row,png_uint_32 filler,png_uint_32 flags)2942 png_do_read_filler(png_row_infop row_info, png_bytep row,
2943 png_uint_32 filler, png_uint_32 flags)
2944 {
2945 png_uint_32 i;
2946 png_uint_32 row_width = row_info->width;
2947
2948 #ifdef PNG_READ_16BIT_SUPPORTED
2949 png_byte hi_filler = (png_byte)((filler>>8) & 0xff);
2950 #endif
2951 png_byte lo_filler = (png_byte)(filler & 0xff);
2952
2953 png_debug(1, "in png_do_read_filler");
2954
2955 if (
2956 row_info->color_type == PNG_COLOR_TYPE_GRAY)
2957 {
2958 if (row_info->bit_depth == 8)
2959 {
2960 if (flags & PNG_FLAG_FILLER_AFTER)
2961 {
2962 /* This changes the data from G to GX */
2963 png_bytep sp = row + (png_size_t)row_width;
2964 png_bytep dp = sp + (png_size_t)row_width;
2965 for (i = 1; i < row_width; i++)
2966 {
2967 *(--dp) = lo_filler;
2968 *(--dp) = *(--sp);
2969 }
2970 *(--dp) = lo_filler;
2971 row_info->channels = 2;
2972 row_info->pixel_depth = 16;
2973 row_info->rowbytes = row_width * 2;
2974 }
2975
2976 else
2977 {
2978 /* This changes the data from G to XG */
2979 png_bytep sp = row + (png_size_t)row_width;
2980 png_bytep dp = sp + (png_size_t)row_width;
2981 for (i = 0; i < row_width; i++)
2982 {
2983 *(--dp) = *(--sp);
2984 *(--dp) = lo_filler;
2985 }
2986 row_info->channels = 2;
2987 row_info->pixel_depth = 16;
2988 row_info->rowbytes = row_width * 2;
2989 }
2990 }
2991
2992 #ifdef PNG_READ_16BIT_SUPPORTED
2993 else if (row_info->bit_depth == 16)
2994 {
2995 if (flags & PNG_FLAG_FILLER_AFTER)
2996 {
2997 /* This changes the data from GG to GGXX */
2998 png_bytep sp = row + (png_size_t)row_width * 2;
2999 png_bytep dp = sp + (png_size_t)row_width * 2;
3000 for (i = 1; i < row_width; i++)
3001 {
3002 *(--dp) = hi_filler;
3003 *(--dp) = lo_filler;
3004 *(--dp) = *(--sp);
3005 *(--dp) = *(--sp);
3006 }
3007 *(--dp) = hi_filler;
3008 *(--dp) = lo_filler;
3009 row_info->channels = 2;
3010 row_info->pixel_depth = 32;
3011 row_info->rowbytes = row_width * 4;
3012 }
3013
3014 else
3015 {
3016 /* This changes the data from GG to XXGG */
3017 png_bytep sp = row + (png_size_t)row_width * 2;
3018 png_bytep dp = sp + (png_size_t)row_width * 2;
3019 for (i = 0; i < row_width; i++)
3020 {
3021 *(--dp) = *(--sp);
3022 *(--dp) = *(--sp);
3023 *(--dp) = hi_filler;
3024 *(--dp) = lo_filler;
3025 }
3026 row_info->channels = 2;
3027 row_info->pixel_depth = 32;
3028 row_info->rowbytes = row_width * 4;
3029 }
3030 }
3031 #endif
3032 } /* COLOR_TYPE == GRAY */
3033 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
3034 {
3035 if (row_info->bit_depth == 8)
3036 {
3037 if (flags & PNG_FLAG_FILLER_AFTER)
3038 {
3039 /* This changes the data from RGB to RGBX */
3040 png_bytep sp = row + (png_size_t)row_width * 3;
3041 png_bytep dp = sp + (png_size_t)row_width;
3042 for (i = 1; i < row_width; i++)
3043 {
3044 *(--dp) = lo_filler;
3045 *(--dp) = *(--sp);
3046 *(--dp) = *(--sp);
3047 *(--dp) = *(--sp);
3048 }
3049 *(--dp) = lo_filler;
3050 row_info->channels = 4;
3051 row_info->pixel_depth = 32;
3052 row_info->rowbytes = row_width * 4;
3053 }
3054
3055 else
3056 {
3057 /* This changes the data from RGB to XRGB */
3058 png_bytep sp = row + (png_size_t)row_width * 3;
3059 png_bytep dp = sp + (png_size_t)row_width;
3060 for (i = 0; i < row_width; i++)
3061 {
3062 *(--dp) = *(--sp);
3063 *(--dp) = *(--sp);
3064 *(--dp) = *(--sp);
3065 *(--dp) = lo_filler;
3066 }
3067 row_info->channels = 4;
3068 row_info->pixel_depth = 32;
3069 row_info->rowbytes = row_width * 4;
3070 }
3071 }
3072
3073 #ifdef PNG_READ_16BIT_SUPPORTED
3074 else if (row_info->bit_depth == 16)
3075 {
3076 if (flags & PNG_FLAG_FILLER_AFTER)
3077 {
3078 /* This changes the data from RRGGBB to RRGGBBXX */
3079 png_bytep sp = row + (png_size_t)row_width * 6;
3080 png_bytep dp = sp + (png_size_t)row_width * 2;
3081 for (i = 1; i < row_width; i++)
3082 {
3083 *(--dp) = hi_filler;
3084 *(--dp) = lo_filler;
3085 *(--dp) = *(--sp);
3086 *(--dp) = *(--sp);
3087 *(--dp) = *(--sp);
3088 *(--dp) = *(--sp);
3089 *(--dp) = *(--sp);
3090 *(--dp) = *(--sp);
3091 }
3092 *(--dp) = hi_filler;
3093 *(--dp) = lo_filler;
3094 row_info->channels = 4;
3095 row_info->pixel_depth = 64;
3096 row_info->rowbytes = row_width * 8;
3097 }
3098
3099 else
3100 {
3101 /* This changes the data from RRGGBB to XXRRGGBB */
3102 png_bytep sp = row + (png_size_t)row_width * 6;
3103 png_bytep dp = sp + (png_size_t)row_width * 2;
3104 for (i = 0; i < row_width; i++)
3105 {
3106 *(--dp) = *(--sp);
3107 *(--dp) = *(--sp);
3108 *(--dp) = *(--sp);
3109 *(--dp) = *(--sp);
3110 *(--dp) = *(--sp);
3111 *(--dp) = *(--sp);
3112 *(--dp) = hi_filler;
3113 *(--dp) = lo_filler;
3114 }
3115
3116 row_info->channels = 4;
3117 row_info->pixel_depth = 64;
3118 row_info->rowbytes = row_width * 8;
3119 }
3120 }
3121 #endif
3122 } /* COLOR_TYPE == RGB */
3123 }
3124 #endif
3125
3126 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
3127 /* Expand grayscale files to RGB, with or without alpha */
3128 void /* PRIVATE */
png_do_gray_to_rgb(png_row_infop row_info,png_bytep row)3129 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
3130 {
3131 png_uint_32 i;
3132 png_uint_32 row_width = row_info->width;
3133
3134 png_debug(1, "in png_do_gray_to_rgb");
3135
3136 if (row_info->bit_depth >= 8 &&
3137 !(row_info->color_type & PNG_COLOR_MASK_COLOR))
3138 {
3139 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
3140 {
3141 if (row_info->bit_depth == 8)
3142 {
3143 /* This changes G to RGB */
3144 png_bytep sp = row + (png_size_t)row_width - 1;
3145 png_bytep dp = sp + (png_size_t)row_width * 2;
3146 for (i = 0; i < row_width; i++)
3147 {
3148 *(dp--) = *sp;
3149 *(dp--) = *sp;
3150 *(dp--) = *(sp--);
3151 }
3152 }
3153
3154 else
3155 {
3156 /* This changes GG to RRGGBB */
3157 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
3158 png_bytep dp = sp + (png_size_t)row_width * 4;
3159 for (i = 0; i < row_width; i++)
3160 {
3161 *(dp--) = *sp;
3162 *(dp--) = *(sp - 1);
3163 *(dp--) = *sp;
3164 *(dp--) = *(sp - 1);
3165 *(dp--) = *(sp--);
3166 *(dp--) = *(sp--);
3167 }
3168 }
3169 }
3170
3171 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
3172 {
3173 if (row_info->bit_depth == 8)
3174 {
3175 /* This changes GA to RGBA */
3176 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
3177 png_bytep dp = sp + (png_size_t)row_width * 2;
3178 for (i = 0; i < row_width; i++)
3179 {
3180 *(dp--) = *(sp--);
3181 *(dp--) = *sp;
3182 *(dp--) = *sp;
3183 *(dp--) = *(sp--);
3184 }
3185 }
3186
3187 else
3188 {
3189 /* This changes GGAA to RRGGBBAA */
3190 png_bytep sp = row + (png_size_t)row_width * 4 - 1;
3191 png_bytep dp = sp + (png_size_t)row_width * 4;
3192 for (i = 0; i < row_width; i++)
3193 {
3194 *(dp--) = *(sp--);
3195 *(dp--) = *(sp--);
3196 *(dp--) = *sp;
3197 *(dp--) = *(sp - 1);
3198 *(dp--) = *sp;
3199 *(dp--) = *(sp - 1);
3200 *(dp--) = *(sp--);
3201 *(dp--) = *(sp--);
3202 }
3203 }
3204 }
3205 row_info->channels = (png_byte)(row_info->channels + 2);
3206 row_info->color_type |= PNG_COLOR_MASK_COLOR;
3207 row_info->pixel_depth = (png_byte)(row_info->channels *
3208 row_info->bit_depth);
3209 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3210 }
3211 }
3212 #endif
3213
3214 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
3215 /* Reduce RGB files to grayscale, with or without alpha
3216 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
3217 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
3218 * versions dated 1998 through November 2002 have been archived at
3219 * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
3220 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
3221 * Charles Poynton poynton at poynton.com
3222 *
3223 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
3224 *
3225 * which can be expressed with integers as
3226 *
3227 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
3228 *
3229 * Poynton's current link (as of January 2003 through July 2011):
3230 * <http://www.poynton.com/notes/colour_and_gamma/>
3231 * has changed the numbers slightly:
3232 *
3233 * Y = 0.2126*R + 0.7152*G + 0.0722*B
3234 *
3235 * which can be expressed with integers as
3236 *
3237 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
3238 *
3239 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
3240 * end point chromaticities and the D65 white point. Depending on the
3241 * precision used for the D65 white point this produces a variety of different
3242 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
3243 * used (0.3127,0.3290) the Y calculation would be:
3244 *
3245 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
3246 *
3247 * While this is correct the rounding results in an overflow for white, because
3248 * the sum of the rounded coefficients is 32769, not 32768. Consequently
3249 * libpng uses, instead, the closest non-overflowing approximation:
3250 *
3251 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
3252 *
3253 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
3254 * (including an sRGB chunk) then the chromaticities are used to calculate the
3255 * coefficients. See the chunk handling in pngrutil.c for more information.
3256 *
3257 * In all cases the calculation is to be done in a linear colorspace. If no
3258 * gamma information is available to correct the encoding of the original RGB
3259 * values this results in an implicit assumption that the original PNG RGB
3260 * values were linear.
3261 *
3262 * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
3263 * the API takes just red and green coefficients the blue coefficient is
3264 * calculated to make the sum 32768. This will result in different rounding
3265 * to that used above.
3266 */
3267 int /* PRIVATE */
png_do_rgb_to_gray(png_structrp png_ptr,png_row_infop row_info,png_bytep row)3268 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
3269
3270 {
3271 int rgb_error = 0;
3272
3273 png_debug(1, "in png_do_rgb_to_gray");
3274
3275 if (!(row_info->color_type & PNG_COLOR_MASK_PALETTE) &&
3276 (row_info->color_type & PNG_COLOR_MASK_COLOR))
3277 {
3278 PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
3279 PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
3280 PNG_CONST png_uint_32 bc = 32768 - rc - gc;
3281 PNG_CONST png_uint_32 row_width = row_info->width;
3282 PNG_CONST int have_alpha =
3283 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
3284
3285 if (row_info->bit_depth == 8)
3286 {
3287 #ifdef PNG_READ_GAMMA_SUPPORTED
3288 /* Notice that gamma to/from 1 are not necessarily inverses (if
3289 * there is an overall gamma correction). Prior to 1.5.5 this code
3290 * checked the linearized values for equality; this doesn't match
3291 * the documentation, the original values must be checked.
3292 */
3293 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
3294 {
3295 png_bytep sp = row;
3296 png_bytep dp = row;
3297 png_uint_32 i;
3298
3299 for (i = 0; i < row_width; i++)
3300 {
3301 png_byte red = *(sp++);
3302 png_byte green = *(sp++);
3303 png_byte blue = *(sp++);
3304
3305 if (red != green || red != blue)
3306 {
3307 red = png_ptr->gamma_to_1[red];
3308 green = png_ptr->gamma_to_1[green];
3309 blue = png_ptr->gamma_to_1[blue];
3310
3311 rgb_error |= 1;
3312 *(dp++) = png_ptr->gamma_from_1[
3313 (rc*red + gc*green + bc*blue + 16384)>>15];
3314 }
3315
3316 else
3317 {
3318 /* If there is no overall correction the table will not be
3319 * set.
3320 */
3321 if (png_ptr->gamma_table != NULL)
3322 red = png_ptr->gamma_table[red];
3323
3324 *(dp++) = red;
3325 }
3326
3327 if (have_alpha)
3328 *(dp++) = *(sp++);
3329 }
3330 }
3331 else
3332 #endif
3333 {
3334 png_bytep sp = row;
3335 png_bytep dp = row;
3336 png_uint_32 i;
3337
3338 for (i = 0; i < row_width; i++)
3339 {
3340 png_byte red = *(sp++);
3341 png_byte green = *(sp++);
3342 png_byte blue = *(sp++);
3343
3344 if (red != green || red != blue)
3345 {
3346 rgb_error |= 1;
3347 /* NOTE: this is the historical approach which simply
3348 * truncates the results.
3349 */
3350 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
3351 }
3352
3353 else
3354 *(dp++) = red;
3355
3356 if (have_alpha)
3357 *(dp++) = *(sp++);
3358 }
3359 }
3360 }
3361
3362 else /* RGB bit_depth == 16 */
3363 {
3364 #ifdef PNG_READ_GAMMA_SUPPORTED
3365 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
3366 {
3367 png_bytep sp = row;
3368 png_bytep dp = row;
3369 png_uint_32 i;
3370
3371 for (i = 0; i < row_width; i++)
3372 {
3373 png_uint_16 red, green, blue, w;
3374
3375 red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3376 green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3377 blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3378
3379 if (red == green && red == blue)
3380 {
3381 if (png_ptr->gamma_16_table != NULL)
3382 w = png_ptr->gamma_16_table[(red&0xff)
3383 >> png_ptr->gamma_shift][red>>8];
3384
3385 else
3386 w = red;
3387 }
3388
3389 else
3390 {
3391 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff)
3392 >> png_ptr->gamma_shift][red>>8];
3393 png_uint_16 green_1 =
3394 png_ptr->gamma_16_to_1[(green&0xff) >>
3395 png_ptr->gamma_shift][green>>8];
3396 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff)
3397 >> png_ptr->gamma_shift][blue>>8];
3398 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
3399 + bc*blue_1 + 16384)>>15);
3400 w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
3401 png_ptr->gamma_shift][gray16 >> 8];
3402 rgb_error |= 1;
3403 }
3404
3405 *(dp++) = (png_byte)((w>>8) & 0xff);
3406 *(dp++) = (png_byte)(w & 0xff);
3407
3408 if (have_alpha)
3409 {
3410 *(dp++) = *(sp++);
3411 *(dp++) = *(sp++);
3412 }
3413 }
3414 }
3415 else
3416 #endif
3417 {
3418 png_bytep sp = row;
3419 png_bytep dp = row;
3420 png_uint_32 i;
3421
3422 for (i = 0; i < row_width; i++)
3423 {
3424 png_uint_16 red, green, blue, gray16;
3425
3426 red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3427 green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3428 blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3429
3430 if (red != green || red != blue)
3431 rgb_error |= 1;
3432
3433 /* From 1.5.5 in the 16 bit case do the accurate conversion even
3434 * in the 'fast' case - this is because this is where the code
3435 * ends up when handling linear 16 bit data.
3436 */
3437 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
3438 15);
3439 *(dp++) = (png_byte)((gray16>>8) & 0xff);
3440 *(dp++) = (png_byte)(gray16 & 0xff);
3441
3442 if (have_alpha)
3443 {
3444 *(dp++) = *(sp++);
3445 *(dp++) = *(sp++);
3446 }
3447 }
3448 }
3449 }
3450
3451 row_info->channels = (png_byte)(row_info->channels - 2);
3452 row_info->color_type = (png_byte)(row_info->color_type &
3453 ~PNG_COLOR_MASK_COLOR);
3454 row_info->pixel_depth = (png_byte)(row_info->channels *
3455 row_info->bit_depth);
3456 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3457 }
3458 return rgb_error;
3459 }
3460 #endif
3461 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
3462
3463 #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
3464 /* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
3465 * large of png_color. This lets grayscale images be treated as
3466 * paletted. Most useful for gamma correction and simplification
3467 * of code. This API is not used internally.
3468 */
3469 void PNGAPI
png_build_grayscale_palette(int bit_depth,png_colorp palette)3470 png_build_grayscale_palette(int bit_depth, png_colorp palette)
3471 {
3472 int num_palette;
3473 int color_inc;
3474 int i;
3475 int v;
3476
3477 png_debug(1, "in png_do_build_grayscale_palette");
3478
3479 if (palette == NULL)
3480 return;
3481
3482 switch (bit_depth)
3483 {
3484 case 1:
3485 num_palette = 2;
3486 color_inc = 0xff;
3487 break;
3488
3489 case 2:
3490 num_palette = 4;
3491 color_inc = 0x55;
3492 break;
3493
3494 case 4:
3495 num_palette = 16;
3496 color_inc = 0x11;
3497 break;
3498
3499 case 8:
3500 num_palette = 256;
3501 color_inc = 1;
3502 break;
3503
3504 default:
3505 num_palette = 0;
3506 color_inc = 0;
3507 break;
3508 }
3509
3510 for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
3511 {
3512 palette[i].red = (png_byte)v;
3513 palette[i].green = (png_byte)v;
3514 palette[i].blue = (png_byte)v;
3515 }
3516 }
3517 #endif
3518
3519
3520 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
3521 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
3522 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
3523 /* Replace any alpha or transparency with the supplied background color.
3524 * "background" is already in the screen gamma, while "background_1" is
3525 * at a gamma of 1.0. Paletted files have already been taken care of.
3526 */
3527 void /* PRIVATE */
png_do_compose(png_row_infop row_info,png_bytep row,png_structrp png_ptr)3528 png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3529 {
3530 #ifdef PNG_READ_GAMMA_SUPPORTED
3531 png_const_bytep gamma_table = png_ptr->gamma_table;
3532 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
3533 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
3534 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
3535 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
3536 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
3537 int gamma_shift = png_ptr->gamma_shift;
3538 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
3539 #endif
3540
3541 png_bytep sp;
3542 png_uint_32 i;
3543 png_uint_32 row_width = row_info->width;
3544 int shift;
3545
3546 png_debug(1, "in png_do_compose");
3547
3548 {
3549 switch (row_info->color_type)
3550 {
3551 case PNG_COLOR_TYPE_GRAY:
3552 {
3553 switch (row_info->bit_depth)
3554 {
3555 case 1:
3556 {
3557 sp = row;
3558 shift = 7;
3559 for (i = 0; i < row_width; i++)
3560 {
3561 if ((png_uint_16)((*sp >> shift) & 0x01)
3562 == png_ptr->trans_color.gray)
3563 {
3564 unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
3565 tmp |= png_ptr->background.gray << shift;
3566 *sp = (png_byte)(tmp & 0xff);
3567 }
3568
3569 if (!shift)
3570 {
3571 shift = 7;
3572 sp++;
3573 }
3574
3575 else
3576 shift--;
3577 }
3578 break;
3579 }
3580
3581 case 2:
3582 {
3583 #ifdef PNG_READ_GAMMA_SUPPORTED
3584 if (gamma_table != NULL)
3585 {
3586 sp = row;
3587 shift = 6;
3588 for (i = 0; i < row_width; i++)
3589 {
3590 if ((png_uint_16)((*sp >> shift) & 0x03)
3591 == png_ptr->trans_color.gray)
3592 {
3593 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3594 tmp |= png_ptr->background.gray << shift;
3595 *sp = (png_byte)(tmp & 0xff);
3596 }
3597
3598 else
3599 {
3600 unsigned int p = (*sp >> shift) & 0x03;
3601 unsigned int g = (gamma_table [p | (p << 2) |
3602 (p << 4) | (p << 6)] >> 6) & 0x03;
3603 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3604 tmp |= g << shift;
3605 *sp = (png_byte)(tmp & 0xff);
3606 }
3607
3608 if (!shift)
3609 {
3610 shift = 6;
3611 sp++;
3612 }
3613
3614 else
3615 shift -= 2;
3616 }
3617 }
3618
3619 else
3620 #endif
3621 {
3622 sp = row;
3623 shift = 6;
3624 for (i = 0; i < row_width; i++)
3625 {
3626 if ((png_uint_16)((*sp >> shift) & 0x03)
3627 == png_ptr->trans_color.gray)
3628 {
3629 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3630 tmp |= png_ptr->background.gray << shift;
3631 *sp = (png_byte)(tmp & 0xff);
3632 }
3633
3634 if (!shift)
3635 {
3636 shift = 6;
3637 sp++;
3638 }
3639
3640 else
3641 shift -= 2;
3642 }
3643 }
3644 break;
3645 }
3646
3647 case 4:
3648 {
3649 #ifdef PNG_READ_GAMMA_SUPPORTED
3650 if (gamma_table != NULL)
3651 {
3652 sp = row;
3653 shift = 4;
3654 for (i = 0; i < row_width; i++)
3655 {
3656 if ((png_uint_16)((*sp >> shift) & 0x0f)
3657 == png_ptr->trans_color.gray)
3658 {
3659 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3660 tmp |= png_ptr->background.gray << shift;
3661 *sp = (png_byte)(tmp & 0xff);
3662 }
3663
3664 else
3665 {
3666 unsigned int p = (*sp >> shift) & 0x0f;
3667 unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
3668 0x0f;
3669 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3670 tmp |= g << shift;
3671 *sp = (png_byte)(tmp & 0xff);
3672 }
3673
3674 if (!shift)
3675 {
3676 shift = 4;
3677 sp++;
3678 }
3679
3680 else
3681 shift -= 4;
3682 }
3683 }
3684
3685 else
3686 #endif
3687 {
3688 sp = row;
3689 shift = 4;
3690 for (i = 0; i < row_width; i++)
3691 {
3692 if ((png_uint_16)((*sp >> shift) & 0x0f)
3693 == png_ptr->trans_color.gray)
3694 {
3695 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3696 tmp |= png_ptr->background.gray << shift;
3697 *sp = (png_byte)(tmp & 0xff);
3698 }
3699
3700 if (!shift)
3701 {
3702 shift = 4;
3703 sp++;
3704 }
3705
3706 else
3707 shift -= 4;
3708 }
3709 }
3710 break;
3711 }
3712
3713 case 8:
3714 {
3715 #ifdef PNG_READ_GAMMA_SUPPORTED
3716 if (gamma_table != NULL)
3717 {
3718 sp = row;
3719 for (i = 0; i < row_width; i++, sp++)
3720 {
3721 if (*sp == png_ptr->trans_color.gray)
3722 *sp = (png_byte)png_ptr->background.gray;
3723
3724 else
3725 *sp = gamma_table[*sp];
3726 }
3727 }
3728 else
3729 #endif
3730 {
3731 sp = row;
3732 for (i = 0; i < row_width; i++, sp++)
3733 {
3734 if (*sp == png_ptr->trans_color.gray)
3735 *sp = (png_byte)png_ptr->background.gray;
3736 }
3737 }
3738 break;
3739 }
3740
3741 case 16:
3742 {
3743 #ifdef PNG_READ_GAMMA_SUPPORTED
3744 if (gamma_16 != NULL)
3745 {
3746 sp = row;
3747 for (i = 0; i < row_width; i++, sp += 2)
3748 {
3749 png_uint_16 v;
3750
3751 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3752
3753 if (v == png_ptr->trans_color.gray)
3754 {
3755 /* Background is already in screen gamma */
3756 *sp = (png_byte)((png_ptr->background.gray >> 8)
3757 & 0xff);
3758 *(sp + 1) = (png_byte)(png_ptr->background.gray
3759 & 0xff);
3760 }
3761
3762 else
3763 {
3764 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3765 *sp = (png_byte)((v >> 8) & 0xff);
3766 *(sp + 1) = (png_byte)(v & 0xff);
3767 }
3768 }
3769 }
3770 else
3771 #endif
3772 {
3773 sp = row;
3774 for (i = 0; i < row_width; i++, sp += 2)
3775 {
3776 png_uint_16 v;
3777
3778 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3779
3780 if (v == png_ptr->trans_color.gray)
3781 {
3782 *sp = (png_byte)((png_ptr->background.gray >> 8)
3783 & 0xff);
3784 *(sp + 1) = (png_byte)(png_ptr->background.gray
3785 & 0xff);
3786 }
3787 }
3788 }
3789 break;
3790 }
3791
3792 default:
3793 break;
3794 }
3795 break;
3796 }
3797
3798 case PNG_COLOR_TYPE_RGB:
3799 {
3800 if (row_info->bit_depth == 8)
3801 {
3802 #ifdef PNG_READ_GAMMA_SUPPORTED
3803 if (gamma_table != NULL)
3804 {
3805 sp = row;
3806 for (i = 0; i < row_width; i++, sp += 3)
3807 {
3808 if (*sp == png_ptr->trans_color.red &&
3809 *(sp + 1) == png_ptr->trans_color.green &&
3810 *(sp + 2) == png_ptr->trans_color.blue)
3811 {
3812 *sp = (png_byte)png_ptr->background.red;
3813 *(sp + 1) = (png_byte)png_ptr->background.green;
3814 *(sp + 2) = (png_byte)png_ptr->background.blue;
3815 }
3816
3817 else
3818 {
3819 *sp = gamma_table[*sp];
3820 *(sp + 1) = gamma_table[*(sp + 1)];
3821 *(sp + 2) = gamma_table[*(sp + 2)];
3822 }
3823 }
3824 }
3825 else
3826 #endif
3827 {
3828 sp = row;
3829 for (i = 0; i < row_width; i++, sp += 3)
3830 {
3831 if (*sp == png_ptr->trans_color.red &&
3832 *(sp + 1) == png_ptr->trans_color.green &&
3833 *(sp + 2) == png_ptr->trans_color.blue)
3834 {
3835 *sp = (png_byte)png_ptr->background.red;
3836 *(sp + 1) = (png_byte)png_ptr->background.green;
3837 *(sp + 2) = (png_byte)png_ptr->background.blue;
3838 }
3839 }
3840 }
3841 }
3842 else /* if (row_info->bit_depth == 16) */
3843 {
3844 #ifdef PNG_READ_GAMMA_SUPPORTED
3845 if (gamma_16 != NULL)
3846 {
3847 sp = row;
3848 for (i = 0; i < row_width; i++, sp += 6)
3849 {
3850 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3851
3852 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3853 + *(sp + 3));
3854
3855 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3856 + *(sp + 5));
3857
3858 if (r == png_ptr->trans_color.red &&
3859 g == png_ptr->trans_color.green &&
3860 b == png_ptr->trans_color.blue)
3861 {
3862 /* Background is already in screen gamma */
3863 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3864 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3865 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3866 & 0xff);
3867 *(sp + 3) = (png_byte)(png_ptr->background.green
3868 & 0xff);
3869 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3870 & 0xff);
3871 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3872 }
3873
3874 else
3875 {
3876 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3877 *sp = (png_byte)((v >> 8) & 0xff);
3878 *(sp + 1) = (png_byte)(v & 0xff);
3879
3880 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3881 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3882 *(sp + 3) = (png_byte)(v & 0xff);
3883
3884 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3885 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3886 *(sp + 5) = (png_byte)(v & 0xff);
3887 }
3888 }
3889 }
3890
3891 else
3892 #endif
3893 {
3894 sp = row;
3895 for (i = 0; i < row_width; i++, sp += 6)
3896 {
3897 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3898
3899 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3900 + *(sp + 3));
3901
3902 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3903 + *(sp + 5));
3904
3905 if (r == png_ptr->trans_color.red &&
3906 g == png_ptr->trans_color.green &&
3907 b == png_ptr->trans_color.blue)
3908 {
3909 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3910 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3911 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3912 & 0xff);
3913 *(sp + 3) = (png_byte)(png_ptr->background.green
3914 & 0xff);
3915 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3916 & 0xff);
3917 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3918 }
3919 }
3920 }
3921 }
3922 break;
3923 }
3924
3925 case PNG_COLOR_TYPE_GRAY_ALPHA:
3926 {
3927 if (row_info->bit_depth == 8)
3928 {
3929 #ifdef PNG_READ_GAMMA_SUPPORTED
3930 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3931 gamma_table != NULL)
3932 {
3933 sp = row;
3934 for (i = 0; i < row_width; i++, sp += 2)
3935 {
3936 png_uint_16 a = *(sp + 1);
3937
3938 if (a == 0xff)
3939 *sp = gamma_table[*sp];
3940
3941 else if (a == 0)
3942 {
3943 /* Background is already in screen gamma */
3944 *sp = (png_byte)png_ptr->background.gray;
3945 }
3946
3947 else
3948 {
3949 png_byte v, w;
3950
3951 v = gamma_to_1[*sp];
3952 png_composite(w, v, a, png_ptr->background_1.gray);
3953 if (!optimize)
3954 w = gamma_from_1[w];
3955 *sp = w;
3956 }
3957 }
3958 }
3959 else
3960 #endif
3961 {
3962 sp = row;
3963 for (i = 0; i < row_width; i++, sp += 2)
3964 {
3965 png_byte a = *(sp + 1);
3966
3967 if (a == 0)
3968 *sp = (png_byte)png_ptr->background.gray;
3969
3970 else if (a < 0xff)
3971 png_composite(*sp, *sp, a, png_ptr->background.gray);
3972 }
3973 }
3974 }
3975 else /* if (png_ptr->bit_depth == 16) */
3976 {
3977 #ifdef PNG_READ_GAMMA_SUPPORTED
3978 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3979 gamma_16_to_1 != NULL)
3980 {
3981 sp = row;
3982 for (i = 0; i < row_width; i++, sp += 4)
3983 {
3984 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3985 + *(sp + 3));
3986
3987 if (a == (png_uint_16)0xffff)
3988 {
3989 png_uint_16 v;
3990
3991 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3992 *sp = (png_byte)((v >> 8) & 0xff);
3993 *(sp + 1) = (png_byte)(v & 0xff);
3994 }
3995
3996 else if (a == 0)
3997 {
3998 /* Background is already in screen gamma */
3999 *sp = (png_byte)((png_ptr->background.gray >> 8)
4000 & 0xff);
4001 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
4002 }
4003
4004 else
4005 {
4006 png_uint_16 g, v, w;
4007
4008 g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
4009 png_composite_16(v, g, a, png_ptr->background_1.gray);
4010 if (optimize)
4011 w = v;
4012 else
4013 w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8];
4014 *sp = (png_byte)((w >> 8) & 0xff);
4015 *(sp + 1) = (png_byte)(w & 0xff);
4016 }
4017 }
4018 }
4019 else
4020 #endif
4021 {
4022 sp = row;
4023 for (i = 0; i < row_width; i++, sp += 4)
4024 {
4025 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
4026 + *(sp + 3));
4027
4028 if (a == 0)
4029 {
4030 *sp = (png_byte)((png_ptr->background.gray >> 8)
4031 & 0xff);
4032 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
4033 }
4034
4035 else if (a < 0xffff)
4036 {
4037 png_uint_16 g, v;
4038
4039 g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
4040 png_composite_16(v, g, a, png_ptr->background.gray);
4041 *sp = (png_byte)((v >> 8) & 0xff);
4042 *(sp + 1) = (png_byte)(v & 0xff);
4043 }
4044 }
4045 }
4046 }
4047 break;
4048 }
4049
4050 case PNG_COLOR_TYPE_RGB_ALPHA:
4051 {
4052 if (row_info->bit_depth == 8)
4053 {
4054 #ifdef PNG_READ_GAMMA_SUPPORTED
4055 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
4056 gamma_table != NULL)
4057 {
4058 sp = row;
4059 for (i = 0; i < row_width; i++, sp += 4)
4060 {
4061 png_byte a = *(sp + 3);
4062
4063 if (a == 0xff)
4064 {
4065 *sp = gamma_table[*sp];
4066 *(sp + 1) = gamma_table[*(sp + 1)];
4067 *(sp + 2) = gamma_table[*(sp + 2)];
4068 }
4069
4070 else if (a == 0)
4071 {
4072 /* Background is already in screen gamma */
4073 *sp = (png_byte)png_ptr->background.red;
4074 *(sp + 1) = (png_byte)png_ptr->background.green;
4075 *(sp + 2) = (png_byte)png_ptr->background.blue;
4076 }
4077
4078 else
4079 {
4080 png_byte v, w;
4081
4082 v = gamma_to_1[*sp];
4083 png_composite(w, v, a, png_ptr->background_1.red);
4084 if (!optimize) w = gamma_from_1[w];
4085 *sp = w;
4086
4087 v = gamma_to_1[*(sp + 1)];
4088 png_composite(w, v, a, png_ptr->background_1.green);
4089 if (!optimize) w = gamma_from_1[w];
4090 *(sp + 1) = w;
4091
4092 v = gamma_to_1[*(sp + 2)];
4093 png_composite(w, v, a, png_ptr->background_1.blue);
4094 if (!optimize) w = gamma_from_1[w];
4095 *(sp + 2) = w;
4096 }
4097 }
4098 }
4099 else
4100 #endif
4101 {
4102 sp = row;
4103 for (i = 0; i < row_width; i++, sp += 4)
4104 {
4105 png_byte a = *(sp + 3);
4106
4107 if (a == 0)
4108 {
4109 *sp = (png_byte)png_ptr->background.red;
4110 *(sp + 1) = (png_byte)png_ptr->background.green;
4111 *(sp + 2) = (png_byte)png_ptr->background.blue;
4112 }
4113
4114 else if (a < 0xff)
4115 {
4116 png_composite(*sp, *sp, a, png_ptr->background.red);
4117
4118 png_composite(*(sp + 1), *(sp + 1), a,
4119 png_ptr->background.green);
4120
4121 png_composite(*(sp + 2), *(sp + 2), a,
4122 png_ptr->background.blue);
4123 }
4124 }
4125 }
4126 }
4127 else /* if (row_info->bit_depth == 16) */
4128 {
4129 #ifdef PNG_READ_GAMMA_SUPPORTED
4130 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
4131 gamma_16_to_1 != NULL)
4132 {
4133 sp = row;
4134 for (i = 0; i < row_width; i++, sp += 8)
4135 {
4136 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
4137 << 8) + (png_uint_16)(*(sp + 7)));
4138
4139 if (a == (png_uint_16)0xffff)
4140 {
4141 png_uint_16 v;
4142
4143 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
4144 *sp = (png_byte)((v >> 8) & 0xff);
4145 *(sp + 1) = (png_byte)(v & 0xff);
4146
4147 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
4148 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
4149 *(sp + 3) = (png_byte)(v & 0xff);
4150
4151 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
4152 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
4153 *(sp + 5) = (png_byte)(v & 0xff);
4154 }
4155
4156 else if (a == 0)
4157 {
4158 /* Background is already in screen gamma */
4159 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
4160 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
4161 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
4162 & 0xff);
4163 *(sp + 3) = (png_byte)(png_ptr->background.green
4164 & 0xff);
4165 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
4166 & 0xff);
4167 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
4168 }
4169
4170 else
4171 {
4172 png_uint_16 v, w;
4173
4174 v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
4175 png_composite_16(w, v, a, png_ptr->background_1.red);
4176 if (!optimize)
4177 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
4178 8];
4179 *sp = (png_byte)((w >> 8) & 0xff);
4180 *(sp + 1) = (png_byte)(w & 0xff);
4181
4182 v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
4183 png_composite_16(w, v, a, png_ptr->background_1.green);
4184 if (!optimize)
4185 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
4186 8];
4187
4188 *(sp + 2) = (png_byte)((w >> 8) & 0xff);
4189 *(sp + 3) = (png_byte)(w & 0xff);
4190
4191 v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
4192 png_composite_16(w, v, a, png_ptr->background_1.blue);
4193 if (!optimize)
4194 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
4195 8];
4196
4197 *(sp + 4) = (png_byte)((w >> 8) & 0xff);
4198 *(sp + 5) = (png_byte)(w & 0xff);
4199 }
4200 }
4201 }
4202
4203 else
4204 #endif
4205 {
4206 sp = row;
4207 for (i = 0; i < row_width; i++, sp += 8)
4208 {
4209 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
4210 << 8) + (png_uint_16)(*(sp + 7)));
4211
4212 if (a == 0)
4213 {
4214 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
4215 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
4216 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
4217 & 0xff);
4218 *(sp + 3) = (png_byte)(png_ptr->background.green
4219 & 0xff);
4220 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
4221 & 0xff);
4222 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
4223 }
4224
4225 else if (a < 0xffff)
4226 {
4227 png_uint_16 v;
4228
4229 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
4230 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
4231 + *(sp + 3));
4232 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
4233 + *(sp + 5));
4234
4235 png_composite_16(v, r, a, png_ptr->background.red);
4236 *sp = (png_byte)((v >> 8) & 0xff);
4237 *(sp + 1) = (png_byte)(v & 0xff);
4238
4239 png_composite_16(v, g, a, png_ptr->background.green);
4240 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
4241 *(sp + 3) = (png_byte)(v & 0xff);
4242
4243 png_composite_16(v, b, a, png_ptr->background.blue);
4244 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
4245 *(sp + 5) = (png_byte)(v & 0xff);
4246 }
4247 }
4248 }
4249 }
4250 break;
4251 }
4252
4253 default:
4254 break;
4255 }
4256 }
4257 }
4258 #endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_READ_ALPHA_MODE_SUPPORTED */
4259
4260 #ifdef PNG_READ_GAMMA_SUPPORTED
4261 /* Gamma correct the image, avoiding the alpha channel. Make sure
4262 * you do this after you deal with the transparency issue on grayscale
4263 * or RGB images. If your bit depth is 8, use gamma_table, if it
4264 * is 16, use gamma_16_table and gamma_shift. Build these with
4265 * build_gamma_table().
4266 */
4267 void /* PRIVATE */
png_do_gamma(png_row_infop row_info,png_bytep row,png_structrp png_ptr)4268 png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
4269 {
4270 png_const_bytep gamma_table = png_ptr->gamma_table;
4271 png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
4272 int gamma_shift = png_ptr->gamma_shift;
4273
4274 png_bytep sp;
4275 png_uint_32 i;
4276 png_uint_32 row_width=row_info->width;
4277
4278 png_debug(1, "in png_do_gamma");
4279
4280 if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
4281 (row_info->bit_depth == 16 && gamma_16_table != NULL)))
4282 {
4283 switch (row_info->color_type)
4284 {
4285 case PNG_COLOR_TYPE_RGB:
4286 {
4287 if (row_info->bit_depth == 8)
4288 {
4289 sp = row;
4290 for (i = 0; i < row_width; i++)
4291 {
4292 *sp = gamma_table[*sp];
4293 sp++;
4294 *sp = gamma_table[*sp];
4295 sp++;
4296 *sp = gamma_table[*sp];
4297 sp++;
4298 }
4299 }
4300
4301 else /* if (row_info->bit_depth == 16) */
4302 {
4303 sp = row;
4304 for (i = 0; i < row_width; i++)
4305 {
4306 png_uint_16 v;
4307
4308 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4309 *sp = (png_byte)((v >> 8) & 0xff);
4310 *(sp + 1) = (png_byte)(v & 0xff);
4311 sp += 2;
4312
4313 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4314 *sp = (png_byte)((v >> 8) & 0xff);
4315 *(sp + 1) = (png_byte)(v & 0xff);
4316 sp += 2;
4317
4318 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4319 *sp = (png_byte)((v >> 8) & 0xff);
4320 *(sp + 1) = (png_byte)(v & 0xff);
4321 sp += 2;
4322 }
4323 }
4324 break;
4325 }
4326
4327 case PNG_COLOR_TYPE_RGB_ALPHA:
4328 {
4329 if (row_info->bit_depth == 8)
4330 {
4331 sp = row;
4332 for (i = 0; i < row_width; i++)
4333 {
4334 *sp = gamma_table[*sp];
4335 sp++;
4336
4337 *sp = gamma_table[*sp];
4338 sp++;
4339
4340 *sp = gamma_table[*sp];
4341 sp++;
4342
4343 sp++;
4344 }
4345 }
4346
4347 else /* if (row_info->bit_depth == 16) */
4348 {
4349 sp = row;
4350 for (i = 0; i < row_width; i++)
4351 {
4352 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4353 *sp = (png_byte)((v >> 8) & 0xff);
4354 *(sp + 1) = (png_byte)(v & 0xff);
4355 sp += 2;
4356
4357 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4358 *sp = (png_byte)((v >> 8) & 0xff);
4359 *(sp + 1) = (png_byte)(v & 0xff);
4360 sp += 2;
4361
4362 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4363 *sp = (png_byte)((v >> 8) & 0xff);
4364 *(sp + 1) = (png_byte)(v & 0xff);
4365 sp += 4;
4366 }
4367 }
4368 break;
4369 }
4370
4371 case PNG_COLOR_TYPE_GRAY_ALPHA:
4372 {
4373 if (row_info->bit_depth == 8)
4374 {
4375 sp = row;
4376 for (i = 0; i < row_width; i++)
4377 {
4378 *sp = gamma_table[*sp];
4379 sp += 2;
4380 }
4381 }
4382
4383 else /* if (row_info->bit_depth == 16) */
4384 {
4385 sp = row;
4386 for (i = 0; i < row_width; i++)
4387 {
4388 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4389 *sp = (png_byte)((v >> 8) & 0xff);
4390 *(sp + 1) = (png_byte)(v & 0xff);
4391 sp += 4;
4392 }
4393 }
4394 break;
4395 }
4396
4397 case PNG_COLOR_TYPE_GRAY:
4398 {
4399 if (row_info->bit_depth == 2)
4400 {
4401 sp = row;
4402 for (i = 0; i < row_width; i += 4)
4403 {
4404 int a = *sp & 0xc0;
4405 int b = *sp & 0x30;
4406 int c = *sp & 0x0c;
4407 int d = *sp & 0x03;
4408
4409 *sp = (png_byte)(
4410 ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)|
4411 ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
4412 ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
4413 ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
4414 sp++;
4415 }
4416 }
4417
4418 if (row_info->bit_depth == 4)
4419 {
4420 sp = row;
4421 for (i = 0; i < row_width; i += 2)
4422 {
4423 int msb = *sp & 0xf0;
4424 int lsb = *sp & 0x0f;
4425
4426 *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
4427 | (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
4428 sp++;
4429 }
4430 }
4431
4432 else if (row_info->bit_depth == 8)
4433 {
4434 sp = row;
4435 for (i = 0; i < row_width; i++)
4436 {
4437 *sp = gamma_table[*sp];
4438 sp++;
4439 }
4440 }
4441
4442 else if (row_info->bit_depth == 16)
4443 {
4444 sp = row;
4445 for (i = 0; i < row_width; i++)
4446 {
4447 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4448 *sp = (png_byte)((v >> 8) & 0xff);
4449 *(sp + 1) = (png_byte)(v & 0xff);
4450 sp += 2;
4451 }
4452 }
4453 break;
4454 }
4455
4456 default:
4457 break;
4458 }
4459 }
4460 }
4461 #endif
4462
4463 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4464 /* Encode the alpha channel to the output gamma (the input channel is always
4465 * linear.) Called only with color types that have an alpha channel. Needs the
4466 * from_1 tables.
4467 */
4468 void /* PRIVATE */
png_do_encode_alpha(png_row_infop row_info,png_bytep row,png_structrp png_ptr)4469 png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
4470 {
4471 png_uint_32 row_width = row_info->width;
4472
4473 png_debug(1, "in png_do_encode_alpha");
4474
4475 if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
4476 {
4477 if (row_info->bit_depth == 8)
4478 {
4479 PNG_CONST png_bytep table = png_ptr->gamma_from_1;
4480
4481 if (table != NULL)
4482 {
4483 PNG_CONST int step =
4484 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
4485
4486 /* The alpha channel is the last component: */
4487 row += step - 1;
4488
4489 for (; row_width > 0; --row_width, row += step)
4490 *row = table[*row];
4491
4492 return;
4493 }
4494 }
4495
4496 else if (row_info->bit_depth == 16)
4497 {
4498 PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1;
4499 PNG_CONST int gamma_shift = png_ptr->gamma_shift;
4500
4501 if (table != NULL)
4502 {
4503 PNG_CONST int step =
4504 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
4505
4506 /* The alpha channel is the last component: */
4507 row += step - 2;
4508
4509 for (; row_width > 0; --row_width, row += step)
4510 {
4511 png_uint_16 v;
4512
4513 v = table[*(row + 1) >> gamma_shift][*row];
4514 *row = (png_byte)((v >> 8) & 0xff);
4515 *(row + 1) = (png_byte)(v & 0xff);
4516 }
4517
4518 return;
4519 }
4520 }
4521 }
4522
4523 /* Only get to here if called with a weird row_info; no harm has been done,
4524 * so just issue a warning.
4525 */
4526 png_warning(png_ptr, "png_do_encode_alpha: unexpected call");
4527 }
4528 #endif
4529
4530 #ifdef PNG_READ_EXPAND_SUPPORTED
4531 /* Expands a palette row to an RGB or RGBA row depending
4532 * upon whether you supply trans and num_trans.
4533 */
4534 void /* PRIVATE */
png_do_expand_palette(png_row_infop row_info,png_bytep row,png_const_colorp palette,png_const_bytep trans_alpha,int num_trans)4535 png_do_expand_palette(png_row_infop row_info, png_bytep row,
4536 png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
4537 {
4538 int shift, value;
4539 png_bytep sp, dp;
4540 png_uint_32 i;
4541 png_uint_32 row_width=row_info->width;
4542
4543 png_debug(1, "in png_do_expand_palette");
4544
4545 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4546 {
4547 if (row_info->bit_depth < 8)
4548 {
4549 switch (row_info->bit_depth)
4550 {
4551 case 1:
4552 {
4553 sp = row + (png_size_t)((row_width - 1) >> 3);
4554 dp = row + (png_size_t)row_width - 1;
4555 shift = 7 - (int)((row_width + 7) & 0x07);
4556 for (i = 0; i < row_width; i++)
4557 {
4558 if ((*sp >> shift) & 0x01)
4559 *dp = 1;
4560
4561 else
4562 *dp = 0;
4563
4564 if (shift == 7)
4565 {
4566 shift = 0;
4567 sp--;
4568 }
4569
4570 else
4571 shift++;
4572
4573 dp--;
4574 }
4575 break;
4576 }
4577
4578 case 2:
4579 {
4580 sp = row + (png_size_t)((row_width - 1) >> 2);
4581 dp = row + (png_size_t)row_width - 1;
4582 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4583 for (i = 0; i < row_width; i++)
4584 {
4585 value = (*sp >> shift) & 0x03;
4586 *dp = (png_byte)value;
4587 if (shift == 6)
4588 {
4589 shift = 0;
4590 sp--;
4591 }
4592
4593 else
4594 shift += 2;
4595
4596 dp--;
4597 }
4598 break;
4599 }
4600
4601 case 4:
4602 {
4603 sp = row + (png_size_t)((row_width - 1) >> 1);
4604 dp = row + (png_size_t)row_width - 1;
4605 shift = (int)((row_width & 0x01) << 2);
4606 for (i = 0; i < row_width; i++)
4607 {
4608 value = (*sp >> shift) & 0x0f;
4609 *dp = (png_byte)value;
4610 if (shift == 4)
4611 {
4612 shift = 0;
4613 sp--;
4614 }
4615
4616 else
4617 shift += 4;
4618
4619 dp--;
4620 }
4621 break;
4622 }
4623
4624 default:
4625 break;
4626 }
4627 row_info->bit_depth = 8;
4628 row_info->pixel_depth = 8;
4629 row_info->rowbytes = row_width;
4630 }
4631
4632 if (row_info->bit_depth == 8)
4633 {
4634 {
4635 if (num_trans > 0)
4636 {
4637 sp = row + (png_size_t)row_width - 1;
4638 dp = row + (png_size_t)(row_width << 2) - 1;
4639
4640 for (i = 0; i < row_width; i++)
4641 {
4642 if ((int)(*sp) >= num_trans)
4643 *dp-- = 0xff;
4644
4645 else
4646 *dp-- = trans_alpha[*sp];
4647
4648 *dp-- = palette[*sp].blue;
4649 *dp-- = palette[*sp].green;
4650 *dp-- = palette[*sp].red;
4651 sp--;
4652 }
4653 row_info->bit_depth = 8;
4654 row_info->pixel_depth = 32;
4655 row_info->rowbytes = row_width * 4;
4656 row_info->color_type = 6;
4657 row_info->channels = 4;
4658 }
4659
4660 else
4661 {
4662 sp = row + (png_size_t)row_width - 1;
4663 dp = row + (png_size_t)(row_width * 3) - 1;
4664
4665 for (i = 0; i < row_width; i++)
4666 {
4667 *dp-- = palette[*sp].blue;
4668 *dp-- = palette[*sp].green;
4669 *dp-- = palette[*sp].red;
4670 sp--;
4671 }
4672
4673 row_info->bit_depth = 8;
4674 row_info->pixel_depth = 24;
4675 row_info->rowbytes = row_width * 3;
4676 row_info->color_type = 2;
4677 row_info->channels = 3;
4678 }
4679 }
4680 }
4681 }
4682 }
4683
4684 /* If the bit depth < 8, it is expanded to 8. Also, if the already
4685 * expanded transparency value is supplied, an alpha channel is built.
4686 */
4687 void /* PRIVATE */
png_do_expand(png_row_infop row_info,png_bytep row,png_const_color_16p trans_color)4688 png_do_expand(png_row_infop row_info, png_bytep row,
4689 png_const_color_16p trans_color)
4690 {
4691 int shift, value;
4692 png_bytep sp, dp;
4693 png_uint_32 i;
4694 png_uint_32 row_width=row_info->width;
4695
4696 png_debug(1, "in png_do_expand");
4697
4698 {
4699 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
4700 {
4701 unsigned int gray = trans_color ? trans_color->gray : 0;
4702
4703 if (row_info->bit_depth < 8)
4704 {
4705 switch (row_info->bit_depth)
4706 {
4707 case 1:
4708 {
4709 gray = (gray & 0x01) * 0xff;
4710 sp = row + (png_size_t)((row_width - 1) >> 3);
4711 dp = row + (png_size_t)row_width - 1;
4712 shift = 7 - (int)((row_width + 7) & 0x07);
4713 for (i = 0; i < row_width; i++)
4714 {
4715 if ((*sp >> shift) & 0x01)
4716 *dp = 0xff;
4717
4718 else
4719 *dp = 0;
4720
4721 if (shift == 7)
4722 {
4723 shift = 0;
4724 sp--;
4725 }
4726
4727 else
4728 shift++;
4729
4730 dp--;
4731 }
4732 break;
4733 }
4734
4735 case 2:
4736 {
4737 gray = (gray & 0x03) * 0x55;
4738 sp = row + (png_size_t)((row_width - 1) >> 2);
4739 dp = row + (png_size_t)row_width - 1;
4740 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4741 for (i = 0; i < row_width; i++)
4742 {
4743 value = (*sp >> shift) & 0x03;
4744 *dp = (png_byte)(value | (value << 2) | (value << 4) |
4745 (value << 6));
4746 if (shift == 6)
4747 {
4748 shift = 0;
4749 sp--;
4750 }
4751
4752 else
4753 shift += 2;
4754
4755 dp--;
4756 }
4757 break;
4758 }
4759
4760 case 4:
4761 {
4762 gray = (gray & 0x0f) * 0x11;
4763 sp = row + (png_size_t)((row_width - 1) >> 1);
4764 dp = row + (png_size_t)row_width - 1;
4765 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
4766 for (i = 0; i < row_width; i++)
4767 {
4768 value = (*sp >> shift) & 0x0f;
4769 *dp = (png_byte)(value | (value << 4));
4770 if (shift == 4)
4771 {
4772 shift = 0;
4773 sp--;
4774 }
4775
4776 else
4777 shift = 4;
4778
4779 dp--;
4780 }
4781 break;
4782 }
4783
4784 default:
4785 break;
4786 }
4787
4788 row_info->bit_depth = 8;
4789 row_info->pixel_depth = 8;
4790 row_info->rowbytes = row_width;
4791 }
4792
4793 if (trans_color != NULL)
4794 {
4795 if (row_info->bit_depth == 8)
4796 {
4797 gray = gray & 0xff;
4798 sp = row + (png_size_t)row_width - 1;
4799 dp = row + (png_size_t)(row_width << 1) - 1;
4800
4801 for (i = 0; i < row_width; i++)
4802 {
4803 if (*sp == gray)
4804 *dp-- = 0;
4805
4806 else
4807 *dp-- = 0xff;
4808
4809 *dp-- = *sp--;
4810 }
4811 }
4812
4813 else if (row_info->bit_depth == 16)
4814 {
4815 unsigned int gray_high = (gray >> 8) & 0xff;
4816 unsigned int gray_low = gray & 0xff;
4817 sp = row + row_info->rowbytes - 1;
4818 dp = row + (row_info->rowbytes << 1) - 1;
4819 for (i = 0; i < row_width; i++)
4820 {
4821 if (*(sp - 1) == gray_high && *(sp) == gray_low)
4822 {
4823 *dp-- = 0;
4824 *dp-- = 0;
4825 }
4826
4827 else
4828 {
4829 *dp-- = 0xff;
4830 *dp-- = 0xff;
4831 }
4832
4833 *dp-- = *sp--;
4834 *dp-- = *sp--;
4835 }
4836 }
4837
4838 row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
4839 row_info->channels = 2;
4840 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
4841 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
4842 row_width);
4843 }
4844 }
4845 else if (row_info->color_type == PNG_COLOR_TYPE_RGB && trans_color)
4846 {
4847 if (row_info->bit_depth == 8)
4848 {
4849 png_byte red = (png_byte)(trans_color->red & 0xff);
4850 png_byte green = (png_byte)(trans_color->green & 0xff);
4851 png_byte blue = (png_byte)(trans_color->blue & 0xff);
4852 sp = row + (png_size_t)row_info->rowbytes - 1;
4853 dp = row + (png_size_t)(row_width << 2) - 1;
4854 for (i = 0; i < row_width; i++)
4855 {
4856 if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
4857 *dp-- = 0;
4858
4859 else
4860 *dp-- = 0xff;
4861
4862 *dp-- = *sp--;
4863 *dp-- = *sp--;
4864 *dp-- = *sp--;
4865 }
4866 }
4867 else if (row_info->bit_depth == 16)
4868 {
4869 png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff);
4870 png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff);
4871 png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff);
4872 png_byte red_low = (png_byte)(trans_color->red & 0xff);
4873 png_byte green_low = (png_byte)(trans_color->green & 0xff);
4874 png_byte blue_low = (png_byte)(trans_color->blue & 0xff);
4875 sp = row + row_info->rowbytes - 1;
4876 dp = row + (png_size_t)(row_width << 3) - 1;
4877 for (i = 0; i < row_width; i++)
4878 {
4879 if (*(sp - 5) == red_high &&
4880 *(sp - 4) == red_low &&
4881 *(sp - 3) == green_high &&
4882 *(sp - 2) == green_low &&
4883 *(sp - 1) == blue_high &&
4884 *(sp ) == blue_low)
4885 {
4886 *dp-- = 0;
4887 *dp-- = 0;
4888 }
4889
4890 else
4891 {
4892 *dp-- = 0xff;
4893 *dp-- = 0xff;
4894 }
4895
4896 *dp-- = *sp--;
4897 *dp-- = *sp--;
4898 *dp-- = *sp--;
4899 *dp-- = *sp--;
4900 *dp-- = *sp--;
4901 *dp-- = *sp--;
4902 }
4903 }
4904 row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
4905 row_info->channels = 4;
4906 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
4907 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4908 }
4909 }
4910 }
4911 #endif
4912
4913 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4914 /* If the bit depth is 8 and the color type is not a palette type expand the
4915 * whole row to 16 bits. Has no effect otherwise.
4916 */
4917 void /* PRIVATE */
png_do_expand_16(png_row_infop row_info,png_bytep row)4918 png_do_expand_16(png_row_infop row_info, png_bytep row)
4919 {
4920 if (row_info->bit_depth == 8 &&
4921 row_info->color_type != PNG_COLOR_TYPE_PALETTE)
4922 {
4923 /* The row have a sequence of bytes containing [0..255] and we need
4924 * to turn it into another row containing [0..65535], to do this we
4925 * calculate:
4926 *
4927 * (input / 255) * 65535
4928 *
4929 * Which happens to be exactly input * 257 and this can be achieved
4930 * simply by byte replication in place (copying backwards).
4931 */
4932 png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */
4933 png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */
4934 while (dp > sp)
4935 dp[-2] = dp[-1] = *--sp, dp -= 2;
4936
4937 row_info->rowbytes *= 2;
4938 row_info->bit_depth = 16;
4939 row_info->pixel_depth = (png_byte)(row_info->channels * 16);
4940 }
4941 }
4942 #endif
4943
4944 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4945 void /* PRIVATE */
png_do_quantize(png_row_infop row_info,png_bytep row,png_const_bytep palette_lookup,png_const_bytep quantize_lookup)4946 png_do_quantize(png_row_infop row_info, png_bytep row,
4947 png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
4948 {
4949 png_bytep sp, dp;
4950 png_uint_32 i;
4951 png_uint_32 row_width=row_info->width;
4952
4953 png_debug(1, "in png_do_quantize");
4954
4955 if (row_info->bit_depth == 8)
4956 {
4957 if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup)
4958 {
4959 int r, g, b, p;
4960 sp = row;
4961 dp = row;
4962 for (i = 0; i < row_width; i++)
4963 {
4964 r = *sp++;
4965 g = *sp++;
4966 b = *sp++;
4967
4968 /* This looks real messy, but the compiler will reduce
4969 * it down to a reasonable formula. For example, with
4970 * 5 bits per color, we get:
4971 * p = (((r >> 3) & 0x1f) << 10) |
4972 * (((g >> 3) & 0x1f) << 5) |
4973 * ((b >> 3) & 0x1f);
4974 */
4975 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4976 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4977 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4978 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4979 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4980 (PNG_QUANTIZE_BLUE_BITS)) |
4981 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4982 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4983
4984 *dp++ = palette_lookup[p];
4985 }
4986
4987 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4988 row_info->channels = 1;
4989 row_info->pixel_depth = row_info->bit_depth;
4990 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4991 }
4992
4993 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
4994 palette_lookup != NULL)
4995 {
4996 int r, g, b, p;
4997 sp = row;
4998 dp = row;
4999 for (i = 0; i < row_width; i++)
5000 {
5001 r = *sp++;
5002 g = *sp++;
5003 b = *sp++;
5004 sp++;
5005
5006 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
5007 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
5008 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
5009 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
5010 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
5011 (PNG_QUANTIZE_BLUE_BITS)) |
5012 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
5013 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
5014
5015 *dp++ = palette_lookup[p];
5016 }
5017
5018 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
5019 row_info->channels = 1;
5020 row_info->pixel_depth = row_info->bit_depth;
5021 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
5022 }
5023
5024 else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
5025 quantize_lookup)
5026 {
5027 sp = row;
5028
5029 for (i = 0; i < row_width; i++, sp++)
5030 {
5031 *sp = quantize_lookup[*sp];
5032 }
5033 }
5034 }
5035 }
5036 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
5037 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
5038
5039 #ifdef PNG_MNG_FEATURES_SUPPORTED
5040 /* Undoes intrapixel differencing */
5041 void /* PRIVATE */
png_do_read_intrapixel(png_row_infop row_info,png_bytep row)5042 png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
5043 {
5044 png_debug(1, "in png_do_read_intrapixel");
5045
5046 if (
5047 (row_info->color_type & PNG_COLOR_MASK_COLOR))
5048 {
5049 int bytes_per_pixel;
5050 png_uint_32 row_width = row_info->width;
5051
5052 if (row_info->bit_depth == 8)
5053 {
5054 png_bytep rp;
5055 png_uint_32 i;
5056
5057 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
5058 bytes_per_pixel = 3;
5059
5060 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
5061 bytes_per_pixel = 4;
5062
5063 else
5064 return;
5065
5066 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
5067 {
5068 *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
5069 *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
5070 }
5071 }
5072 else if (row_info->bit_depth == 16)
5073 {
5074 png_bytep rp;
5075 png_uint_32 i;
5076
5077 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
5078 bytes_per_pixel = 6;
5079
5080 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
5081 bytes_per_pixel = 8;
5082
5083 else
5084 return;
5085
5086 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
5087 {
5088 png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
5089 png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
5090 png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
5091 png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
5092 png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
5093 *(rp ) = (png_byte)((red >> 8) & 0xff);
5094 *(rp + 1) = (png_byte)(red & 0xff);
5095 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
5096 *(rp + 5) = (png_byte)(blue & 0xff);
5097 }
5098 }
5099 }
5100 }
5101 #endif /* PNG_MNG_FEATURES_SUPPORTED */
5102 #endif /* PNG_READ_SUPPORTED */
5103