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