1
2 /* pngrtran.c - transforms the data in a row for PNG readers
3 *
4 * Last changed in libpng 1.6.35 [July 15, 2018]
5 * Copyright (c) 1998-2002,2004,2006-2018 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 /* FALLTHROUGH */
53 case PNG_CRC_ERROR_QUIT: /* Error/quit */
54
55 case PNG_CRC_DEFAULT:
56 default:
57 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
58 break;
59 }
60
61 /* Tell libpng how we react to CRC errors in ancillary chunks */
62 switch (ancil_action)
63 {
64 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
65 break;
66
67 case PNG_CRC_WARN_USE: /* Warn/use data */
68 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
69 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
70 break;
71
72 case PNG_CRC_QUIET_USE: /* Quiet/use data */
73 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
74 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
75 PNG_FLAG_CRC_ANCILLARY_NOWARN;
76 break;
77
78 case PNG_CRC_ERROR_QUIT: /* Error/quit */
79 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
80 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
81 break;
82
83 case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
84
85 case PNG_CRC_DEFAULT:
86 default:
87 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
88 break;
89 }
90 }
91
92 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
93 /* Is it OK to set a transformation now? Only if png_start_read_image or
94 * png_read_update_info have not been called. It is not necessary for the IHDR
95 * to have been read in all cases; the need_IHDR parameter allows for this
96 * check too.
97 */
98 static int
png_rtran_ok(png_structrp png_ptr,int need_IHDR)99 png_rtran_ok(png_structrp png_ptr, int need_IHDR)
100 {
101 if (png_ptr != NULL)
102 {
103 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
104 png_app_error(png_ptr,
105 "invalid after png_start_read_image or png_read_update_info");
106
107 else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
108 png_app_error(png_ptr, "invalid before the PNG header has been read");
109
110 else
111 {
112 /* Turn on failure to initialize correctly for all transforms. */
113 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
114
115 return 1; /* Ok */
116 }
117 }
118
119 return 0; /* no png_error possible! */
120 }
121 #endif
122
123 #ifdef PNG_READ_BACKGROUND_SUPPORTED
124 /* Handle alpha and tRNS via a background color */
125 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)126 png_set_background_fixed(png_structrp png_ptr,
127 png_const_color_16p background_color, int background_gamma_code,
128 int need_expand, png_fixed_point background_gamma)
129 {
130 png_debug(1, "in png_set_background_fixed");
131
132 if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL)
133 return;
134
135 if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
136 {
137 png_warning(png_ptr, "Application must supply a known background gamma");
138 return;
139 }
140
141 png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
142 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
143 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
144
145 png_ptr->background = *background_color;
146 png_ptr->background_gamma = background_gamma;
147 png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
148 if (need_expand != 0)
149 png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
150 else
151 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
152 }
153
154 # ifdef PNG_FLOATING_POINT_SUPPORTED
155 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)156 png_set_background(png_structrp png_ptr,
157 png_const_color_16p background_color, int background_gamma_code,
158 int need_expand, double background_gamma)
159 {
160 png_set_background_fixed(png_ptr, background_color, background_gamma_code,
161 need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
162 }
163 # endif /* FLOATING_POINT */
164 #endif /* READ_BACKGROUND */
165
166 /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
167 * one that pngrtran does first (scale) happens. This is necessary to allow the
168 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
169 */
170 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
171 void PNGAPI
png_set_scale_16(png_structrp png_ptr)172 png_set_scale_16(png_structrp png_ptr)
173 {
174 png_debug(1, "in png_set_scale_16");
175
176 if (png_rtran_ok(png_ptr, 0) == 0)
177 return;
178
179 png_ptr->transformations |= PNG_SCALE_16_TO_8;
180 }
181 #endif
182
183 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
184 /* Chop 16-bit depth files to 8-bit depth */
185 void PNGAPI
png_set_strip_16(png_structrp png_ptr)186 png_set_strip_16(png_structrp png_ptr)
187 {
188 png_debug(1, "in png_set_strip_16");
189
190 if (png_rtran_ok(png_ptr, 0) == 0)
191 return;
192
193 png_ptr->transformations |= PNG_16_TO_8;
194 }
195 #endif
196
197 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
198 void PNGAPI
png_set_strip_alpha(png_structrp png_ptr)199 png_set_strip_alpha(png_structrp png_ptr)
200 {
201 png_debug(1, "in png_set_strip_alpha");
202
203 if (png_rtran_ok(png_ptr, 0) == 0)
204 return;
205
206 png_ptr->transformations |= PNG_STRIP_ALPHA;
207 }
208 #endif
209
210 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
211 static png_fixed_point
translate_gamma_flags(png_structrp png_ptr,png_fixed_point output_gamma,int is_screen)212 translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
213 int is_screen)
214 {
215 /* Check for flag values. The main reason for having the old Mac value as a
216 * flag is that it is pretty near impossible to work out what the correct
217 * value is from Apple documentation - a working Mac system is needed to
218 * discover the value!
219 */
220 if (output_gamma == PNG_DEFAULT_sRGB ||
221 output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
222 {
223 /* If there is no sRGB support this just sets the gamma to the standard
224 * sRGB value. (This is a side effect of using this function!)
225 */
226 # ifdef PNG_READ_sRGB_SUPPORTED
227 png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
228 # else
229 PNG_UNUSED(png_ptr)
230 # endif
231 if (is_screen != 0)
232 output_gamma = PNG_GAMMA_sRGB;
233 else
234 output_gamma = PNG_GAMMA_sRGB_INVERSE;
235 }
236
237 else if (output_gamma == PNG_GAMMA_MAC_18 ||
238 output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
239 {
240 if (is_screen != 0)
241 output_gamma = PNG_GAMMA_MAC_OLD;
242 else
243 output_gamma = PNG_GAMMA_MAC_INVERSE;
244 }
245
246 return output_gamma;
247 }
248
249 # ifdef PNG_FLOATING_POINT_SUPPORTED
250 static png_fixed_point
convert_gamma_value(png_structrp png_ptr,double output_gamma)251 convert_gamma_value(png_structrp png_ptr, double output_gamma)
252 {
253 /* The following silently ignores cases where fixed point (times 100,000)
254 * gamma values are passed to the floating point API. This is safe and it
255 * means the fixed point constants work just fine with the floating point
256 * API. The alternative would just lead to undetected errors and spurious
257 * bug reports. Negative values fail inside the _fixed API unless they
258 * correspond to the flag values.
259 */
260 if (output_gamma > 0 && output_gamma < 128)
261 output_gamma *= PNG_FP_1;
262
263 /* This preserves -1 and -2 exactly: */
264 output_gamma = floor(output_gamma + .5);
265
266 if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
267 png_fixed_error(png_ptr, "gamma value");
268
269 return (png_fixed_point)output_gamma;
270 }
271 # endif
272 #endif /* READ_ALPHA_MODE || READ_GAMMA */
273
274 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
275 void PNGFAPI
png_set_alpha_mode_fixed(png_structrp png_ptr,int mode,png_fixed_point output_gamma)276 png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
277 png_fixed_point output_gamma)
278 {
279 int compose = 0;
280 png_fixed_point file_gamma;
281
282 png_debug(1, "in png_set_alpha_mode");
283
284 if (png_rtran_ok(png_ptr, 0) == 0)
285 return;
286
287 output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
288
289 /* Validate the value to ensure it is in a reasonable range. The value
290 * is expected to be 1 or greater, but this range test allows for some
291 * viewing correction values. The intent is to weed out users of this API
292 * who use the inverse of the gamma value accidentally! Since some of these
293 * values are reasonable this may have to be changed:
294 *
295 * 1.6.x: changed from 0.07..3 to 0.01..100 (to accommodate the optimal 16-bit
296 * gamma of 36, and its reciprocal.)
297 */
298 if (output_gamma < 1000 || output_gamma > 10000000)
299 png_error(png_ptr, "output gamma out of expected range");
300
301 /* The default file gamma is the inverse of the output gamma; the output
302 * gamma may be changed below so get the file value first:
303 */
304 file_gamma = png_reciprocal(output_gamma);
305
306 /* There are really 8 possibilities here, composed of any combination
307 * of:
308 *
309 * premultiply the color channels
310 * do not encode non-opaque pixels
311 * encode the alpha as well as the color channels
312 *
313 * The differences disappear if the input/output ('screen') gamma is 1.0,
314 * because then the encoding is a no-op and there is only the choice of
315 * premultiplying the color channels or not.
316 *
317 * png_set_alpha_mode and png_set_background interact because both use
318 * png_compose to do the work. Calling both is only useful when
319 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
320 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
321 */
322 switch (mode)
323 {
324 case PNG_ALPHA_PNG: /* default: png standard */
325 /* No compose, but it may be set by png_set_background! */
326 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
327 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
328 break;
329
330 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
331 compose = 1;
332 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
333 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
334 /* The output is linear: */
335 output_gamma = PNG_FP_1;
336 break;
337
338 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
339 compose = 1;
340 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
341 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
342 /* output_gamma records the encoding of opaque pixels! */
343 break;
344
345 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
346 compose = 1;
347 png_ptr->transformations |= PNG_ENCODE_ALPHA;
348 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
349 break;
350
351 default:
352 png_error(png_ptr, "invalid alpha mode");
353 }
354
355 /* Only set the default gamma if the file gamma has not been set (this has
356 * the side effect that the gamma in a second call to png_set_alpha_mode will
357 * be ignored.)
358 */
359 if (png_ptr->colorspace.gamma == 0)
360 {
361 png_ptr->colorspace.gamma = file_gamma;
362 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
363 }
364
365 /* But always set the output gamma: */
366 png_ptr->screen_gamma = output_gamma;
367
368 /* Finally, if pre-multiplying, set the background fields to achieve the
369 * desired result.
370 */
371 if (compose != 0)
372 {
373 /* And obtain alpha pre-multiplication by composing on black: */
374 memset(&png_ptr->background, 0, (sizeof png_ptr->background));
375 png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
376 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
377 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
378
379 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
380 png_error(png_ptr,
381 "conflicting calls to set alpha mode and background");
382
383 png_ptr->transformations |= PNG_COMPOSE;
384 }
385 }
386
387 # ifdef PNG_FLOATING_POINT_SUPPORTED
388 void PNGAPI
png_set_alpha_mode(png_structrp png_ptr,int mode,double output_gamma)389 png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
390 {
391 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
392 output_gamma));
393 }
394 # endif
395 #endif
396
397 #ifdef PNG_READ_QUANTIZE_SUPPORTED
398 /* Dither file to 8-bit. Supply a palette, the current number
399 * of elements in the palette, the maximum number of elements
400 * allowed, and a histogram if possible. If the current number
401 * of colors is greater than the maximum number, the palette will be
402 * modified to fit in the maximum number. "full_quantize" indicates
403 * whether we need a quantizing cube set up for RGB images, or if we
404 * simply are reducing the number of colors in a paletted image.
405 */
406
407 typedef struct png_dsort_struct
408 {
409 struct png_dsort_struct * next;
410 png_byte left;
411 png_byte right;
412 } png_dsort;
413 typedef png_dsort * png_dsortp;
414 typedef png_dsort * * png_dsortpp;
415
416 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)417 png_set_quantize(png_structrp png_ptr, png_colorp palette,
418 int num_palette, int maximum_colors, png_const_uint_16p histogram,
419 int full_quantize)
420 {
421 png_debug(1, "in png_set_quantize");
422
423 if (png_rtran_ok(png_ptr, 0) == 0)
424 return;
425
426 png_ptr->transformations |= PNG_QUANTIZE;
427
428 if (full_quantize == 0)
429 {
430 int i;
431
432 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
433 (png_alloc_size_t)((png_uint_32)num_palette * (sizeof (png_byte))));
434 for (i = 0; i < num_palette; i++)
435 png_ptr->quantize_index[i] = (png_byte)i;
436 }
437
438 if (num_palette > maximum_colors)
439 {
440 if (histogram != NULL)
441 {
442 /* This is easy enough, just throw out the least used colors.
443 * Perhaps not the best solution, but good enough.
444 */
445
446 int i;
447
448 /* Initialize an array to sort colors */
449 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
450 (png_alloc_size_t)((png_uint_32)num_palette * (sizeof (png_byte))));
451
452 /* Initialize the quantize_sort array */
453 for (i = 0; i < num_palette; i++)
454 png_ptr->quantize_sort[i] = (png_byte)i;
455
456 /* Find the least used palette entries by starting a
457 * bubble sort, and running it until we have sorted
458 * out enough colors. Note that we don't care about
459 * sorting all the colors, just finding which are
460 * least used.
461 */
462
463 for (i = num_palette - 1; i >= maximum_colors; i--)
464 {
465 int done; /* To stop early if the list is pre-sorted */
466 int j;
467
468 done = 1;
469 for (j = 0; j < i; j++)
470 {
471 if (histogram[png_ptr->quantize_sort[j]]
472 < histogram[png_ptr->quantize_sort[j + 1]])
473 {
474 png_byte t;
475
476 t = png_ptr->quantize_sort[j];
477 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
478 png_ptr->quantize_sort[j + 1] = t;
479 done = 0;
480 }
481 }
482
483 if (done != 0)
484 break;
485 }
486
487 /* Swap the palette around, and set up a table, if necessary */
488 if (full_quantize != 0)
489 {
490 int j = num_palette;
491
492 /* Put all the useful colors within the max, but don't
493 * move the others.
494 */
495 for (i = 0; i < maximum_colors; i++)
496 {
497 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
498 {
499 do
500 j--;
501 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
502
503 palette[i] = palette[j];
504 }
505 }
506 }
507 else
508 {
509 int j = num_palette;
510
511 /* Move all the used colors inside the max limit, and
512 * develop a translation table.
513 */
514 for (i = 0; i < maximum_colors; i++)
515 {
516 /* Only move the colors we need to */
517 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
518 {
519 png_color tmp_color;
520
521 do
522 j--;
523 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
524
525 tmp_color = palette[j];
526 palette[j] = palette[i];
527 palette[i] = tmp_color;
528 /* Indicate where the color went */
529 png_ptr->quantize_index[j] = (png_byte)i;
530 png_ptr->quantize_index[i] = (png_byte)j;
531 }
532 }
533
534 /* Find closest color for those colors we are not using */
535 for (i = 0; i < num_palette; i++)
536 {
537 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
538 {
539 int min_d, k, min_k, d_index;
540
541 /* Find the closest color to one we threw out */
542 d_index = png_ptr->quantize_index[i];
543 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
544 for (k = 1, min_k = 0; k < maximum_colors; k++)
545 {
546 int d;
547
548 d = PNG_COLOR_DIST(palette[d_index], palette[k]);
549
550 if (d < min_d)
551 {
552 min_d = d;
553 min_k = k;
554 }
555 }
556 /* Point to closest color */
557 png_ptr->quantize_index[i] = (png_byte)min_k;
558 }
559 }
560 }
561 png_free(png_ptr, png_ptr->quantize_sort);
562 png_ptr->quantize_sort = NULL;
563 }
564 else
565 {
566 /* This is much harder to do simply (and quickly). Perhaps
567 * we need to go through a median cut routine, but those
568 * don't always behave themselves with only a few colors
569 * as input. So we will just find the closest two colors,
570 * and throw out one of them (chosen somewhat randomly).
571 * [We don't understand this at all, so if someone wants to
572 * work on improving it, be our guest - AED, GRP]
573 */
574 int i;
575 int max_d;
576 int num_new_palette;
577 png_dsortp t;
578 png_dsortpp hash;
579
580 t = NULL;
581
582 /* Initialize palette index arrays */
583 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
584 (png_alloc_size_t)((png_uint_32)num_palette *
585 (sizeof (png_byte))));
586 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
587 (png_alloc_size_t)((png_uint_32)num_palette *
588 (sizeof (png_byte))));
589
590 /* Initialize the sort array */
591 for (i = 0; i < num_palette; i++)
592 {
593 png_ptr->index_to_palette[i] = (png_byte)i;
594 png_ptr->palette_to_index[i] = (png_byte)i;
595 }
596
597 hash = (png_dsortpp)png_calloc(png_ptr, (png_alloc_size_t)(769 *
598 (sizeof (png_dsortp))));
599
600 num_new_palette = num_palette;
601
602 /* Initial wild guess at how far apart the farthest pixel
603 * pair we will be eliminating will be. Larger
604 * numbers mean more areas will be allocated, Smaller
605 * numbers run the risk of not saving enough data, and
606 * having to do this all over again.
607 *
608 * I have not done extensive checking on this number.
609 */
610 max_d = 96;
611
612 while (num_new_palette > maximum_colors)
613 {
614 for (i = 0; i < num_new_palette - 1; i++)
615 {
616 int j;
617
618 for (j = i + 1; j < num_new_palette; j++)
619 {
620 int d;
621
622 d = PNG_COLOR_DIST(palette[i], palette[j]);
623
624 if (d <= max_d)
625 {
626
627 t = (png_dsortp)png_malloc_warn(png_ptr,
628 (png_alloc_size_t)(sizeof (png_dsort)));
629
630 if (t == NULL)
631 break;
632
633 t->next = hash[d];
634 t->left = (png_byte)i;
635 t->right = (png_byte)j;
636 hash[d] = t;
637 }
638 }
639 if (t == NULL)
640 break;
641 }
642
643 if (t != NULL)
644 for (i = 0; i <= max_d; i++)
645 {
646 if (hash[i] != NULL)
647 {
648 png_dsortp p;
649
650 for (p = hash[i]; p; p = p->next)
651 {
652 if ((int)png_ptr->index_to_palette[p->left]
653 < num_new_palette &&
654 (int)png_ptr->index_to_palette[p->right]
655 < num_new_palette)
656 {
657 int j, next_j;
658
659 if (num_new_palette & 0x01)
660 {
661 j = p->left;
662 next_j = p->right;
663 }
664 else
665 {
666 j = p->right;
667 next_j = p->left;
668 }
669
670 num_new_palette--;
671 palette[png_ptr->index_to_palette[j]]
672 = palette[num_new_palette];
673 if (full_quantize == 0)
674 {
675 int k;
676
677 for (k = 0; k < num_palette; k++)
678 {
679 if (png_ptr->quantize_index[k] ==
680 png_ptr->index_to_palette[j])
681 png_ptr->quantize_index[k] =
682 png_ptr->index_to_palette[next_j];
683
684 if ((int)png_ptr->quantize_index[k] ==
685 num_new_palette)
686 png_ptr->quantize_index[k] =
687 png_ptr->index_to_palette[j];
688 }
689 }
690
691 png_ptr->index_to_palette[png_ptr->palette_to_index
692 [num_new_palette]] = png_ptr->index_to_palette[j];
693
694 png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
695 = png_ptr->palette_to_index[num_new_palette];
696
697 png_ptr->index_to_palette[j] =
698 (png_byte)num_new_palette;
699
700 png_ptr->palette_to_index[num_new_palette] =
701 (png_byte)j;
702 }
703 if (num_new_palette <= maximum_colors)
704 break;
705 }
706 if (num_new_palette <= maximum_colors)
707 break;
708 }
709 }
710
711 for (i = 0; i < 769; i++)
712 {
713 if (hash[i] != NULL)
714 {
715 png_dsortp p = hash[i];
716 while (p)
717 {
718 t = p->next;
719 png_free(png_ptr, p);
720 p = t;
721 }
722 }
723 hash[i] = 0;
724 }
725 max_d += 96;
726 }
727 png_free(png_ptr, hash);
728 png_free(png_ptr, png_ptr->palette_to_index);
729 png_free(png_ptr, png_ptr->index_to_palette);
730 png_ptr->palette_to_index = NULL;
731 png_ptr->index_to_palette = NULL;
732 }
733 num_palette = maximum_colors;
734 }
735 if (png_ptr->palette == NULL)
736 {
737 png_ptr->palette = palette;
738 }
739 png_ptr->num_palette = (png_uint_16)num_palette;
740
741 if (full_quantize != 0)
742 {
743 int i;
744 png_bytep distance;
745 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
746 PNG_QUANTIZE_BLUE_BITS;
747 int num_red = (1 << PNG_QUANTIZE_RED_BITS);
748 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
749 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
750 size_t num_entries = ((size_t)1 << total_bits);
751
752 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
753 (png_alloc_size_t)(num_entries * (sizeof (png_byte))));
754
755 distance = (png_bytep)png_malloc(png_ptr, (png_alloc_size_t)(num_entries *
756 (sizeof (png_byte))));
757
758 memset(distance, 0xff, num_entries * (sizeof (png_byte)));
759
760 for (i = 0; i < num_palette; i++)
761 {
762 int ir, ig, ib;
763 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
764 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
765 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
766
767 for (ir = 0; ir < num_red; ir++)
768 {
769 /* int dr = abs(ir - r); */
770 int dr = ((ir > r) ? ir - r : r - ir);
771 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
772 PNG_QUANTIZE_GREEN_BITS));
773
774 for (ig = 0; ig < num_green; ig++)
775 {
776 /* int dg = abs(ig - g); */
777 int dg = ((ig > g) ? ig - g : g - ig);
778 int dt = dr + dg;
779 int dm = ((dr > dg) ? dr : dg);
780 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
781
782 for (ib = 0; ib < num_blue; ib++)
783 {
784 int d_index = index_g | ib;
785 /* int db = abs(ib - b); */
786 int db = ((ib > b) ? ib - b : b - ib);
787 int dmax = ((dm > db) ? dm : db);
788 int d = dmax + dt + db;
789
790 if (d < (int)distance[d_index])
791 {
792 distance[d_index] = (png_byte)d;
793 png_ptr->palette_lookup[d_index] = (png_byte)i;
794 }
795 }
796 }
797 }
798 }
799
800 png_free(png_ptr, distance);
801 }
802 }
803 #endif /* READ_QUANTIZE */
804
805 #ifdef PNG_READ_GAMMA_SUPPORTED
806 void PNGFAPI
png_set_gamma_fixed(png_structrp png_ptr,png_fixed_point scrn_gamma,png_fixed_point file_gamma)807 png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
808 png_fixed_point file_gamma)
809 {
810 png_debug(1, "in png_set_gamma_fixed");
811
812 if (png_rtran_ok(png_ptr, 0) == 0)
813 return;
814
815 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
816 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
817 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
818
819 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
820 * premultiplied alpha support; this actually hides an undocumented feature
821 * of the previous implementation which allowed gamma processing to be
822 * disabled in background handling. There is no evidence (so far) that this
823 * was being used; however, png_set_background itself accepted and must still
824 * accept '0' for the gamma value it takes, because it isn't always used.
825 *
826 * Since this is an API change (albeit a very minor one that removes an
827 * undocumented API feature) the following checks were only enabled in
828 * libpng-1.6.0.
829 */
830 if (file_gamma <= 0)
831 png_error(png_ptr, "invalid file gamma in png_set_gamma");
832
833 if (scrn_gamma <= 0)
834 png_error(png_ptr, "invalid screen gamma in png_set_gamma");
835
836 /* Set the gamma values unconditionally - this overrides the value in the PNG
837 * file if a gAMA chunk was present. png_set_alpha_mode provides a
838 * different, easier, way to default the file gamma.
839 */
840 png_ptr->colorspace.gamma = file_gamma;
841 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
842 png_ptr->screen_gamma = scrn_gamma;
843 }
844
845 # ifdef PNG_FLOATING_POINT_SUPPORTED
846 void PNGAPI
png_set_gamma(png_structrp png_ptr,double scrn_gamma,double file_gamma)847 png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
848 {
849 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
850 convert_gamma_value(png_ptr, file_gamma));
851 }
852 # endif /* FLOATING_POINT */
853 #endif /* READ_GAMMA */
854
855 #ifdef PNG_READ_EXPAND_SUPPORTED
856 /* Expand paletted images to RGB, expand grayscale images of
857 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
858 * to alpha channels.
859 */
860 void PNGAPI
png_set_expand(png_structrp png_ptr)861 png_set_expand(png_structrp png_ptr)
862 {
863 png_debug(1, "in png_set_expand");
864
865 if (png_rtran_ok(png_ptr, 0) == 0)
866 return;
867
868 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
869 }
870
871 /* GRR 19990627: the following three functions currently are identical
872 * to png_set_expand(). However, it is entirely reasonable that someone
873 * might wish to expand an indexed image to RGB but *not* expand a single,
874 * fully transparent palette entry to a full alpha channel--perhaps instead
875 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
876 * the transparent color with a particular RGB value, or drop tRNS entirely.
877 * IOW, a future version of the library may make the transformations flag
878 * a bit more fine-grained, with separate bits for each of these three
879 * functions.
880 *
881 * More to the point, these functions make it obvious what libpng will be
882 * doing, whereas "expand" can (and does) mean any number of things.
883 *
884 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
885 * to expand only the sample depth but not to expand the tRNS to alpha
886 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
887 */
888
889 /* Expand paletted images to RGB. */
890 void PNGAPI
png_set_palette_to_rgb(png_structrp png_ptr)891 png_set_palette_to_rgb(png_structrp png_ptr)
892 {
893 png_debug(1, "in png_set_palette_to_rgb");
894
895 if (png_rtran_ok(png_ptr, 0) == 0)
896 return;
897
898 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
899 }
900
901 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
902 void PNGAPI
png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)903 png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
904 {
905 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
906
907 if (png_rtran_ok(png_ptr, 0) == 0)
908 return;
909
910 png_ptr->transformations |= PNG_EXPAND;
911 }
912
913 /* Expand tRNS chunks to alpha channels. */
914 void PNGAPI
png_set_tRNS_to_alpha(png_structrp png_ptr)915 png_set_tRNS_to_alpha(png_structrp png_ptr)
916 {
917 png_debug(1, "in png_set_tRNS_to_alpha");
918
919 if (png_rtran_ok(png_ptr, 0) == 0)
920 return;
921
922 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
923 }
924 #endif /* READ_EXPAND */
925
926 #ifdef PNG_READ_EXPAND_16_SUPPORTED
927 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
928 * it may not work correctly.)
929 */
930 void PNGAPI
png_set_expand_16(png_structrp png_ptr)931 png_set_expand_16(png_structrp png_ptr)
932 {
933 png_debug(1, "in png_set_expand_16");
934
935 if (png_rtran_ok(png_ptr, 0) == 0)
936 return;
937
938 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
939 }
940 #endif
941
942 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
943 void PNGAPI
png_set_gray_to_rgb(png_structrp png_ptr)944 png_set_gray_to_rgb(png_structrp png_ptr)
945 {
946 png_debug(1, "in png_set_gray_to_rgb");
947
948 if (png_rtran_ok(png_ptr, 0) == 0)
949 return;
950
951 /* Because rgb must be 8 bits or more: */
952 png_set_expand_gray_1_2_4_to_8(png_ptr);
953 png_ptr->transformations |= PNG_GRAY_TO_RGB;
954 }
955 #endif
956
957 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
958 void PNGFAPI
png_set_rgb_to_gray_fixed(png_structrp png_ptr,int error_action,png_fixed_point red,png_fixed_point green)959 png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
960 png_fixed_point red, png_fixed_point green)
961 {
962 png_debug(1, "in png_set_rgb_to_gray");
963
964 /* Need the IHDR here because of the check on color_type below. */
965 /* TODO: fix this */
966 if (png_rtran_ok(png_ptr, 1) == 0)
967 return;
968
969 switch (error_action)
970 {
971 case PNG_ERROR_ACTION_NONE:
972 png_ptr->transformations |= PNG_RGB_TO_GRAY;
973 break;
974
975 case PNG_ERROR_ACTION_WARN:
976 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
977 break;
978
979 case PNG_ERROR_ACTION_ERROR:
980 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
981 break;
982
983 default:
984 png_error(png_ptr, "invalid error action to rgb_to_gray");
985 }
986
987 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
988 #ifdef PNG_READ_EXPAND_SUPPORTED
989 png_ptr->transformations |= PNG_EXPAND;
990 #else
991 {
992 /* Make this an error in 1.6 because otherwise the application may assume
993 * that it just worked and get a memory overwrite.
994 */
995 png_error(png_ptr,
996 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
997
998 /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
999 }
1000 #endif
1001 {
1002 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
1003 {
1004 png_uint_16 red_int, green_int;
1005
1006 /* NOTE: this calculation does not round, but this behavior is retained
1007 * for consistency; the inaccuracy is very small. The code here always
1008 * overwrites the coefficients, regardless of whether they have been
1009 * defaulted or set already.
1010 */
1011 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
1012 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
1013
1014 png_ptr->rgb_to_gray_red_coeff = red_int;
1015 png_ptr->rgb_to_gray_green_coeff = green_int;
1016 png_ptr->rgb_to_gray_coefficients_set = 1;
1017 }
1018
1019 else
1020 {
1021 if (red >= 0 && green >= 0)
1022 png_app_warning(png_ptr,
1023 "ignoring out of range rgb_to_gray coefficients");
1024
1025 /* Use the defaults, from the cHRM chunk if set, else the historical
1026 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
1027 * png_do_rgb_to_gray for more discussion of the values. In this case
1028 * the coefficients are not marked as 'set' and are not overwritten if
1029 * something has already provided a default.
1030 */
1031 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
1032 png_ptr->rgb_to_gray_green_coeff == 0)
1033 {
1034 png_ptr->rgb_to_gray_red_coeff = 6968;
1035 png_ptr->rgb_to_gray_green_coeff = 23434;
1036 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1037 }
1038 }
1039 }
1040 }
1041
1042 #ifdef PNG_FLOATING_POINT_SUPPORTED
1043 /* Convert a RGB image to a grayscale of the same width. This allows us,
1044 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1045 */
1046
1047 void PNGAPI
png_set_rgb_to_gray(png_structrp png_ptr,int error_action,double red,double green)1048 png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
1049 double green)
1050 {
1051 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1052 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
1053 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
1054 }
1055 #endif /* FLOATING POINT */
1056
1057 #endif /* RGB_TO_GRAY */
1058
1059 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1060 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1061 void PNGAPI
png_set_read_user_transform_fn(png_structrp png_ptr,png_user_transform_ptr read_user_transform_fn)1062 png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1063 read_user_transform_fn)
1064 {
1065 png_debug(1, "in png_set_read_user_transform_fn");
1066
1067 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1068 png_ptr->transformations |= PNG_USER_TRANSFORM;
1069 png_ptr->read_user_transform_fn = read_user_transform_fn;
1070 #endif
1071 }
1072 #endif
1073
1074 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1075 #ifdef PNG_READ_GAMMA_SUPPORTED
1076 /* In the case of gamma transformations only do transformations on images where
1077 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1078 * slows things down slightly, and also needlessly introduces small errors.
1079 */
1080 static int /* PRIVATE */
png_gamma_threshold(png_fixed_point screen_gamma,png_fixed_point file_gamma)1081 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
1082 {
1083 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1084 * correction as a difference of the overall transform from 1.0
1085 *
1086 * We want to compare the threshold with s*f - 1, if we get
1087 * overflow here it is because of wacky gamma values so we
1088 * turn on processing anyway.
1089 */
1090 png_fixed_point gtest;
1091 return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) ||
1092 png_gamma_significant(gtest);
1093 }
1094 #endif
1095
1096 /* Initialize everything needed for the read. This includes modifying
1097 * the palette.
1098 */
1099
1100 /* For the moment 'png_init_palette_transformations' and
1101 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1102 * The intent is that these two routines should have palette or rgb operations
1103 * extracted from 'png_init_read_transformations'.
1104 */
1105 static void /* PRIVATE */
png_init_palette_transformations(png_structrp png_ptr)1106 png_init_palette_transformations(png_structrp png_ptr)
1107 {
1108 /* Called to handle the (input) palette case. In png_do_read_transformations
1109 * the first step is to expand the palette if requested, so this code must
1110 * take care to only make changes that are invariant with respect to the
1111 * palette expansion, or only do them if there is no expansion.
1112 *
1113 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1114 * to 0.)
1115 */
1116 int input_has_alpha = 0;
1117 int input_has_transparency = 0;
1118
1119 if (png_ptr->num_trans > 0)
1120 {
1121 int i;
1122
1123 /* Ignore if all the entries are opaque (unlikely!) */
1124 for (i=0; i<png_ptr->num_trans; ++i)
1125 {
1126 if (png_ptr->trans_alpha[i] == 255)
1127 continue;
1128 else if (png_ptr->trans_alpha[i] == 0)
1129 input_has_transparency = 1;
1130 else
1131 {
1132 input_has_transparency = 1;
1133 input_has_alpha = 1;
1134 break;
1135 }
1136 }
1137 }
1138
1139 /* If no alpha we can optimize. */
1140 if (input_has_alpha == 0)
1141 {
1142 /* Any alpha means background and associative alpha processing is
1143 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1144 * and ENCODE_ALPHA are irrelevant.
1145 */
1146 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1147 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1148
1149 if (input_has_transparency == 0)
1150 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1151 }
1152
1153 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1154 /* png_set_background handling - deals with the complexity of whether the
1155 * background color is in the file format or the screen format in the case
1156 * where an 'expand' will happen.
1157 */
1158
1159 /* The following code cannot be entered in the alpha pre-multiplication case
1160 * because PNG_BACKGROUND_EXPAND is cancelled below.
1161 */
1162 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1163 (png_ptr->transformations & PNG_EXPAND) != 0)
1164 {
1165 {
1166 png_ptr->background.red =
1167 png_ptr->palette[png_ptr->background.index].red;
1168 png_ptr->background.green =
1169 png_ptr->palette[png_ptr->background.index].green;
1170 png_ptr->background.blue =
1171 png_ptr->palette[png_ptr->background.index].blue;
1172
1173 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1174 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
1175 {
1176 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1177 {
1178 /* Invert the alpha channel (in tRNS) unless the pixels are
1179 * going to be expanded, in which case leave it for later
1180 */
1181 int i, istop = png_ptr->num_trans;
1182
1183 for (i=0; i<istop; i++)
1184 png_ptr->trans_alpha[i] = (png_byte)(255 -
1185 png_ptr->trans_alpha[i]);
1186 }
1187 }
1188 #endif /* READ_INVERT_ALPHA */
1189 }
1190 } /* background expand and (therefore) no alpha association. */
1191 #endif /* READ_EXPAND && READ_BACKGROUND */
1192 }
1193
1194 static void /* PRIVATE */
png_init_rgb_transformations(png_structrp png_ptr)1195 png_init_rgb_transformations(png_structrp png_ptr)
1196 {
1197 /* Added to libpng-1.5.4: check the color type to determine whether there
1198 * is any alpha or transparency in the image and simply cancel the
1199 * background and alpha mode stuff if there isn't.
1200 */
1201 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
1202 int input_has_transparency = png_ptr->num_trans > 0;
1203
1204 /* If no alpha we can optimize. */
1205 if (input_has_alpha == 0)
1206 {
1207 /* Any alpha means background and associative alpha processing is
1208 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1209 * and ENCODE_ALPHA are irrelevant.
1210 */
1211 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1212 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1213 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1214 # endif
1215
1216 if (input_has_transparency == 0)
1217 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1218 }
1219
1220 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1221 /* png_set_background handling - deals with the complexity of whether the
1222 * background color is in the file format or the screen format in the case
1223 * where an 'expand' will happen.
1224 */
1225
1226 /* The following code cannot be entered in the alpha pre-multiplication case
1227 * because PNG_BACKGROUND_EXPAND is cancelled below.
1228 */
1229 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1230 (png_ptr->transformations & PNG_EXPAND) != 0 &&
1231 (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1232 /* i.e., GRAY or GRAY_ALPHA */
1233 {
1234 {
1235 /* Expand background and tRNS chunks */
1236 int gray = png_ptr->background.gray;
1237 int trans_gray = png_ptr->trans_color.gray;
1238
1239 switch (png_ptr->bit_depth)
1240 {
1241 case 1:
1242 gray *= 0xff;
1243 trans_gray *= 0xff;
1244 break;
1245
1246 case 2:
1247 gray *= 0x55;
1248 trans_gray *= 0x55;
1249 break;
1250
1251 case 4:
1252 gray *= 0x11;
1253 trans_gray *= 0x11;
1254 break;
1255
1256 default:
1257
1258 case 8:
1259 /* FALLTHROUGH */ /* (Already 8 bits) */
1260
1261 case 16:
1262 /* Already a full 16 bits */
1263 break;
1264 }
1265
1266 png_ptr->background.red = png_ptr->background.green =
1267 png_ptr->background.blue = (png_uint_16)gray;
1268
1269 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1270 {
1271 png_ptr->trans_color.red = png_ptr->trans_color.green =
1272 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
1273 }
1274 }
1275 } /* background expand and (therefore) no alpha association. */
1276 #endif /* READ_EXPAND && READ_BACKGROUND */
1277 }
1278
1279 void /* PRIVATE */
png_init_read_transformations(png_structrp png_ptr)1280 png_init_read_transformations(png_structrp png_ptr)
1281 {
1282 png_debug(1, "in png_init_read_transformations");
1283
1284 /* This internal function is called from png_read_start_row in pngrutil.c
1285 * and it is called before the 'rowbytes' calculation is done, so the code
1286 * in here can change or update the transformations flags.
1287 *
1288 * First do updates that do not depend on the details of the PNG image data
1289 * being processed.
1290 */
1291
1292 #ifdef PNG_READ_GAMMA_SUPPORTED
1293 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1294 * png_set_alpha_mode and this is another source for a default file gamma so
1295 * the test needs to be performed later - here. In addition prior to 1.5.4
1296 * the tests were repeated for the PALETTE color type here - this is no
1297 * longer necessary (and doesn't seem to have been necessary before.)
1298 */
1299 {
1300 /* The following temporary indicates if overall gamma correction is
1301 * required.
1302 */
1303 int gamma_correction = 0;
1304
1305 if (png_ptr->colorspace.gamma != 0) /* has been set */
1306 {
1307 if (png_ptr->screen_gamma != 0) /* screen set too */
1308 gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
1309 png_ptr->screen_gamma);
1310
1311 else
1312 /* Assume the output matches the input; a long time default behavior
1313 * of libpng, although the standard has nothing to say about this.
1314 */
1315 png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
1316 }
1317
1318 else if (png_ptr->screen_gamma != 0)
1319 /* The converse - assume the file matches the screen, note that this
1320 * perhaps undesirable default can (from 1.5.4) be changed by calling
1321 * png_set_alpha_mode (even if the alpha handling mode isn't required
1322 * or isn't changed from the default.)
1323 */
1324 png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
1325
1326 else /* neither are set */
1327 /* Just in case the following prevents any processing - file and screen
1328 * are both assumed to be linear and there is no way to introduce a
1329 * third gamma value other than png_set_background with 'UNIQUE', and,
1330 * prior to 1.5.4
1331 */
1332 png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
1333
1334 /* We have a gamma value now. */
1335 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
1336
1337 /* Now turn the gamma transformation on or off as appropriate. Notice
1338 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1339 * composition may independently cause gamma correction because it needs
1340 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1341 * hasn't been specified.) In any case this flag may get turned off in
1342 * the code immediately below if the transform can be handled outside the
1343 * row loop.
1344 */
1345 if (gamma_correction != 0)
1346 png_ptr->transformations |= PNG_GAMMA;
1347
1348 else
1349 png_ptr->transformations &= ~PNG_GAMMA;
1350 }
1351 #endif
1352
1353 /* Certain transformations have the effect of preventing other
1354 * transformations that happen afterward in png_do_read_transformations;
1355 * resolve the interdependencies here. From the code of
1356 * png_do_read_transformations the order is:
1357 *
1358 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1359 * 2) PNG_STRIP_ALPHA (if no compose)
1360 * 3) PNG_RGB_TO_GRAY
1361 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1362 * 5) PNG_COMPOSE
1363 * 6) PNG_GAMMA
1364 * 7) PNG_STRIP_ALPHA (if compose)
1365 * 8) PNG_ENCODE_ALPHA
1366 * 9) PNG_SCALE_16_TO_8
1367 * 10) PNG_16_TO_8
1368 * 11) PNG_QUANTIZE (converts to palette)
1369 * 12) PNG_EXPAND_16
1370 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1371 * 14) PNG_INVERT_MONO
1372 * 15) PNG_INVERT_ALPHA
1373 * 16) PNG_SHIFT
1374 * 17) PNG_PACK
1375 * 18) PNG_BGR
1376 * 19) PNG_PACKSWAP
1377 * 20) PNG_FILLER (includes PNG_ADD_ALPHA)
1378 * 21) PNG_SWAP_ALPHA
1379 * 22) PNG_SWAP_BYTES
1380 * 23) PNG_USER_TRANSFORM [must be last]
1381 */
1382 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1383 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
1384 (png_ptr->transformations & PNG_COMPOSE) == 0)
1385 {
1386 /* Stripping the alpha channel happens immediately after the 'expand'
1387 * transformations, before all other transformation, so it cancels out
1388 * the alpha handling. It has the side effect negating the effect of
1389 * PNG_EXPAND_tRNS too:
1390 */
1391 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
1392 PNG_EXPAND_tRNS);
1393 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1394
1395 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1396 * so transparency information would remain just so long as it wasn't
1397 * expanded. This produces unexpected API changes if the set of things
1398 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1399 * documentation - which says ask for what you want, accept what you
1400 * get.) This makes the behavior consistent from 1.5.4:
1401 */
1402 png_ptr->num_trans = 0;
1403 }
1404 #endif /* STRIP_ALPHA supported, no COMPOSE */
1405
1406 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1407 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1408 * settings will have no effect.
1409 */
1410 if (png_gamma_significant(png_ptr->screen_gamma) == 0)
1411 {
1412 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1413 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1414 }
1415 #endif
1416
1417 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1418 /* Make sure the coefficients for the rgb to gray conversion are set
1419 * appropriately.
1420 */
1421 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1422 png_colorspace_set_rgb_coefficients(png_ptr);
1423 #endif
1424
1425 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1426 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1427 /* Detect gray background and attempt to enable optimization for
1428 * gray --> RGB case.
1429 *
1430 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1431 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1432 * background color might actually be gray yet not be flagged as such.
1433 * This is not a problem for the current code, which uses
1434 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1435 * png_do_gray_to_rgb() transformation.
1436 *
1437 * TODO: this code needs to be revised to avoid the complexity and
1438 * interdependencies. The color type of the background should be recorded in
1439 * png_set_background, along with the bit depth, then the code has a record
1440 * of exactly what color space the background is currently in.
1441 */
1442 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0)
1443 {
1444 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1445 * the file was grayscale the background value is gray.
1446 */
1447 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1448 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1449 }
1450
1451 else if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1452 {
1453 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1454 * so the color is in the color space of the output or png_set_alpha_mode
1455 * was called and the color is black. Ignore RGB_TO_GRAY because that
1456 * happens before GRAY_TO_RGB.
1457 */
1458 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
1459 {
1460 if (png_ptr->background.red == png_ptr->background.green &&
1461 png_ptr->background.red == png_ptr->background.blue)
1462 {
1463 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1464 png_ptr->background.gray = png_ptr->background.red;
1465 }
1466 }
1467 }
1468 #endif /* READ_EXPAND && READ_BACKGROUND */
1469 #endif /* READ_GRAY_TO_RGB */
1470
1471 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1472 * can be performed directly on the palette, and some (such as rgb to gray)
1473 * can be optimized inside the palette. This is particularly true of the
1474 * composite (background and alpha) stuff, which can be pretty much all done
1475 * in the palette even if the result is expanded to RGB or gray afterward.
1476 *
1477 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1478 * earlier and the palette stuff is actually handled on the first row. This
1479 * leads to the reported bug that the palette returned by png_get_PLTE is not
1480 * updated.
1481 */
1482 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1483 png_init_palette_transformations(png_ptr);
1484
1485 else
1486 png_init_rgb_transformations(png_ptr);
1487
1488 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1489 defined(PNG_READ_EXPAND_16_SUPPORTED)
1490 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
1491 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1492 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1493 png_ptr->bit_depth != 16)
1494 {
1495 /* TODO: fix this. Because the expand_16 operation is after the compose
1496 * handling the background color must be 8, not 16, bits deep, but the
1497 * application will supply a 16-bit value so reduce it here.
1498 *
1499 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1500 * present, so that case is ok (until do_expand_16 is moved.)
1501 *
1502 * NOTE: this discards the low 16 bits of the user supplied background
1503 * color, but until expand_16 works properly there is no choice!
1504 */
1505 # define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
1506 CHOP(png_ptr->background.red);
1507 CHOP(png_ptr->background.green);
1508 CHOP(png_ptr->background.blue);
1509 CHOP(png_ptr->background.gray);
1510 # undef CHOP
1511 }
1512 #endif /* READ_BACKGROUND && READ_EXPAND_16 */
1513
1514 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1515 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1516 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1517 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 &&
1518 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1519 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1520 png_ptr->bit_depth == 16)
1521 {
1522 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1523 * component this will also happen after PNG_COMPOSE and so the background
1524 * color must be pre-expanded here.
1525 *
1526 * TODO: fix this too.
1527 */
1528 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
1529 png_ptr->background.green =
1530 (png_uint_16)(png_ptr->background.green * 257);
1531 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
1532 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
1533 }
1534 #endif
1535
1536 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1537 * background support (see the comments in scripts/pnglibconf.dfa), this
1538 * allows pre-multiplication of the alpha channel to be implemented as
1539 * compositing on black. This is probably sub-optimal and has been done in
1540 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1541 * implement the new API quickly, without lots of internal changes.)
1542 */
1543
1544 #ifdef PNG_READ_GAMMA_SUPPORTED
1545 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1546 /* Includes ALPHA_MODE */
1547 png_ptr->background_1 = png_ptr->background;
1548 # endif
1549
1550 /* This needs to change - in the palette image case a whole set of tables are
1551 * built when it would be quicker to just calculate the correct value for
1552 * each palette entry directly. Also, the test is too tricky - why check
1553 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1554 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1555 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1556 * the gamma tables will not be built even if composition is required on a
1557 * gamma encoded value.
1558 *
1559 * In 1.5.4 this is addressed below by an additional check on the individual
1560 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1561 * tables.
1562 */
1563 if ((png_ptr->transformations & PNG_GAMMA) != 0 ||
1564 ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 &&
1565 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1566 png_gamma_significant(png_ptr->screen_gamma) != 0)) ||
1567 ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1568 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1569 png_gamma_significant(png_ptr->screen_gamma) != 0
1570 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1571 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE &&
1572 png_gamma_significant(png_ptr->background_gamma) != 0)
1573 # endif
1574 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
1575 png_gamma_significant(png_ptr->screen_gamma) != 0))
1576 {
1577 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
1578
1579 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1580 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1581 {
1582 /* Issue a warning about this combination: because RGB_TO_GRAY is
1583 * optimized to do the gamma transform if present yet do_background has
1584 * to do the same thing if both options are set a
1585 * double-gamma-correction happens. This is true in all versions of
1586 * libpng to date.
1587 */
1588 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1589 png_warning(png_ptr,
1590 "libpng does not support gamma+background+rgb_to_gray");
1591
1592 if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
1593 {
1594 /* We don't get to here unless there is a tRNS chunk with non-opaque
1595 * entries - see the checking code at the start of this function.
1596 */
1597 png_color back, back_1;
1598 png_colorp palette = png_ptr->palette;
1599 int num_palette = png_ptr->num_palette;
1600 int i;
1601 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
1602 {
1603
1604 back.red = png_ptr->gamma_table[png_ptr->background.red];
1605 back.green = png_ptr->gamma_table[png_ptr->background.green];
1606 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
1607
1608 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
1609 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
1610 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
1611 }
1612 else
1613 {
1614 png_fixed_point g, gs;
1615
1616 switch (png_ptr->background_gamma_type)
1617 {
1618 case PNG_BACKGROUND_GAMMA_SCREEN:
1619 g = (png_ptr->screen_gamma);
1620 gs = PNG_FP_1;
1621 break;
1622
1623 case PNG_BACKGROUND_GAMMA_FILE:
1624 g = png_reciprocal(png_ptr->colorspace.gamma);
1625 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1626 png_ptr->screen_gamma);
1627 break;
1628
1629 case PNG_BACKGROUND_GAMMA_UNIQUE:
1630 g = png_reciprocal(png_ptr->background_gamma);
1631 gs = png_reciprocal2(png_ptr->background_gamma,
1632 png_ptr->screen_gamma);
1633 break;
1634 default:
1635 g = PNG_FP_1; /* back_1 */
1636 gs = PNG_FP_1; /* back */
1637 break;
1638 }
1639
1640 if (png_gamma_significant(gs) != 0)
1641 {
1642 back.red = png_gamma_8bit_correct(png_ptr->background.red,
1643 gs);
1644 back.green = png_gamma_8bit_correct(png_ptr->background.green,
1645 gs);
1646 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1647 gs);
1648 }
1649
1650 else
1651 {
1652 back.red = (png_byte)png_ptr->background.red;
1653 back.green = (png_byte)png_ptr->background.green;
1654 back.blue = (png_byte)png_ptr->background.blue;
1655 }
1656
1657 if (png_gamma_significant(g) != 0)
1658 {
1659 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
1660 g);
1661 back_1.green = png_gamma_8bit_correct(
1662 png_ptr->background.green, g);
1663 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1664 g);
1665 }
1666
1667 else
1668 {
1669 back_1.red = (png_byte)png_ptr->background.red;
1670 back_1.green = (png_byte)png_ptr->background.green;
1671 back_1.blue = (png_byte)png_ptr->background.blue;
1672 }
1673 }
1674
1675 for (i = 0; i < num_palette; i++)
1676 {
1677 if (i < (int)png_ptr->num_trans &&
1678 png_ptr->trans_alpha[i] != 0xff)
1679 {
1680 if (png_ptr->trans_alpha[i] == 0)
1681 {
1682 palette[i] = back;
1683 }
1684 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1685 {
1686 png_byte v, w;
1687
1688 v = png_ptr->gamma_to_1[palette[i].red];
1689 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
1690 palette[i].red = png_ptr->gamma_from_1[w];
1691
1692 v = png_ptr->gamma_to_1[palette[i].green];
1693 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
1694 palette[i].green = png_ptr->gamma_from_1[w];
1695
1696 v = png_ptr->gamma_to_1[palette[i].blue];
1697 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
1698 palette[i].blue = png_ptr->gamma_from_1[w];
1699 }
1700 }
1701 else
1702 {
1703 palette[i].red = png_ptr->gamma_table[palette[i].red];
1704 palette[i].green = png_ptr->gamma_table[palette[i].green];
1705 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1706 }
1707 }
1708
1709 /* Prevent the transformations being done again.
1710 *
1711 * NOTE: this is highly dubious; it removes the transformations in
1712 * place. This seems inconsistent with the general treatment of the
1713 * transformations elsewhere.
1714 */
1715 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
1716 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1717
1718 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1719 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1720 {
1721 int gs_sig, g_sig;
1722 png_fixed_point g = PNG_FP_1; /* Correction to linear */
1723 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
1724
1725 switch (png_ptr->background_gamma_type)
1726 {
1727 case PNG_BACKGROUND_GAMMA_SCREEN:
1728 g = png_ptr->screen_gamma;
1729 /* gs = PNG_FP_1; */
1730 break;
1731
1732 case PNG_BACKGROUND_GAMMA_FILE:
1733 g = png_reciprocal(png_ptr->colorspace.gamma);
1734 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1735 png_ptr->screen_gamma);
1736 break;
1737
1738 case PNG_BACKGROUND_GAMMA_UNIQUE:
1739 g = png_reciprocal(png_ptr->background_gamma);
1740 gs = png_reciprocal2(png_ptr->background_gamma,
1741 png_ptr->screen_gamma);
1742 break;
1743
1744 default:
1745 png_error(png_ptr, "invalid background gamma type");
1746 }
1747
1748 g_sig = png_gamma_significant(g);
1749 gs_sig = png_gamma_significant(gs);
1750
1751 if (g_sig != 0)
1752 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
1753 png_ptr->background.gray, g);
1754
1755 if (gs_sig != 0)
1756 png_ptr->background.gray = png_gamma_correct(png_ptr,
1757 png_ptr->background.gray, gs);
1758
1759 if ((png_ptr->background.red != png_ptr->background.green) ||
1760 (png_ptr->background.red != png_ptr->background.blue) ||
1761 (png_ptr->background.red != png_ptr->background.gray))
1762 {
1763 /* RGB or RGBA with color background */
1764 if (g_sig != 0)
1765 {
1766 png_ptr->background_1.red = png_gamma_correct(png_ptr,
1767 png_ptr->background.red, g);
1768
1769 png_ptr->background_1.green = png_gamma_correct(png_ptr,
1770 png_ptr->background.green, g);
1771
1772 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
1773 png_ptr->background.blue, g);
1774 }
1775
1776 if (gs_sig != 0)
1777 {
1778 png_ptr->background.red = png_gamma_correct(png_ptr,
1779 png_ptr->background.red, gs);
1780
1781 png_ptr->background.green = png_gamma_correct(png_ptr,
1782 png_ptr->background.green, gs);
1783
1784 png_ptr->background.blue = png_gamma_correct(png_ptr,
1785 png_ptr->background.blue, gs);
1786 }
1787 }
1788
1789 else
1790 {
1791 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1792 png_ptr->background_1.red = png_ptr->background_1.green
1793 = png_ptr->background_1.blue = png_ptr->background_1.gray;
1794
1795 png_ptr->background.red = png_ptr->background.green
1796 = png_ptr->background.blue = png_ptr->background.gray;
1797 }
1798
1799 /* The background is now in screen gamma: */
1800 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
1801 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1802 }/* png_ptr->transformations & PNG_BACKGROUND */
1803
1804 else
1805 /* Transformation does not include PNG_BACKGROUND */
1806 #endif /* READ_BACKGROUND */
1807 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
1808 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1809 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1810 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
1811 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
1812 #endif
1813 )
1814 {
1815 png_colorp palette = png_ptr->palette;
1816 int num_palette = png_ptr->num_palette;
1817 int i;
1818
1819 /* NOTE: there are other transformations that should probably be in
1820 * here too.
1821 */
1822 for (i = 0; i < num_palette; i++)
1823 {
1824 palette[i].red = png_ptr->gamma_table[palette[i].red];
1825 palette[i].green = png_ptr->gamma_table[palette[i].green];
1826 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1827 }
1828
1829 /* Done the gamma correction. */
1830 png_ptr->transformations &= ~PNG_GAMMA;
1831 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1832 }
1833 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1834 else
1835 #endif
1836 #endif /* READ_GAMMA */
1837
1838 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1839 /* No GAMMA transformation (see the hanging else 4 lines above) */
1840 if ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1841 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1842 {
1843 int i;
1844 int istop = (int)png_ptr->num_trans;
1845 png_color back;
1846 png_colorp palette = png_ptr->palette;
1847
1848 back.red = (png_byte)png_ptr->background.red;
1849 back.green = (png_byte)png_ptr->background.green;
1850 back.blue = (png_byte)png_ptr->background.blue;
1851
1852 for (i = 0; i < istop; i++)
1853 {
1854 if (png_ptr->trans_alpha[i] == 0)
1855 {
1856 palette[i] = back;
1857 }
1858
1859 else if (png_ptr->trans_alpha[i] != 0xff)
1860 {
1861 /* The png_composite() macro is defined in png.h */
1862 png_composite(palette[i].red, palette[i].red,
1863 png_ptr->trans_alpha[i], back.red);
1864
1865 png_composite(palette[i].green, palette[i].green,
1866 png_ptr->trans_alpha[i], back.green);
1867
1868 png_composite(palette[i].blue, palette[i].blue,
1869 png_ptr->trans_alpha[i], back.blue);
1870 }
1871 }
1872
1873 png_ptr->transformations &= ~PNG_COMPOSE;
1874 }
1875 #endif /* READ_BACKGROUND */
1876
1877 #ifdef PNG_READ_SHIFT_SUPPORTED
1878 if ((png_ptr->transformations & PNG_SHIFT) != 0 &&
1879 (png_ptr->transformations & PNG_EXPAND) == 0 &&
1880 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1881 {
1882 int i;
1883 int istop = png_ptr->num_palette;
1884 int shift = 8 - png_ptr->sig_bit.red;
1885
1886 png_ptr->transformations &= ~PNG_SHIFT;
1887
1888 /* significant bits can be in the range 1 to 7 for a meaningful result, if
1889 * the number of significant bits is 0 then no shift is done (this is an
1890 * error condition which is silently ignored.)
1891 */
1892 if (shift > 0 && shift < 8)
1893 for (i=0; i<istop; ++i)
1894 {
1895 int component = png_ptr->palette[i].red;
1896
1897 component >>= shift;
1898 png_ptr->palette[i].red = (png_byte)component;
1899 }
1900
1901 shift = 8 - png_ptr->sig_bit.green;
1902 if (shift > 0 && shift < 8)
1903 for (i=0; i<istop; ++i)
1904 {
1905 int component = png_ptr->palette[i].green;
1906
1907 component >>= shift;
1908 png_ptr->palette[i].green = (png_byte)component;
1909 }
1910
1911 shift = 8 - png_ptr->sig_bit.blue;
1912 if (shift > 0 && shift < 8)
1913 for (i=0; i<istop; ++i)
1914 {
1915 int component = png_ptr->palette[i].blue;
1916
1917 component >>= shift;
1918 png_ptr->palette[i].blue = (png_byte)component;
1919 }
1920 }
1921 #endif /* READ_SHIFT */
1922 }
1923
1924 /* Modify the info structure to reflect the transformations. The
1925 * info should be updated so a PNG file could be written with it,
1926 * assuming the transformations result in valid PNG data.
1927 */
1928 void /* PRIVATE */
png_read_transform_info(png_structrp png_ptr,png_inforp info_ptr)1929 png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
1930 {
1931 png_debug(1, "in png_read_transform_info");
1932
1933 #ifdef PNG_READ_EXPAND_SUPPORTED
1934 if ((png_ptr->transformations & PNG_EXPAND) != 0)
1935 {
1936 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1937 {
1938 /* This check must match what actually happens in
1939 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1940 * it is all opaque we must do the same (at present it does not.)
1941 */
1942 if (png_ptr->num_trans > 0)
1943 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
1944
1945 else
1946 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
1947
1948 info_ptr->bit_depth = 8;
1949 info_ptr->num_trans = 0;
1950
1951 if (png_ptr->palette == NULL)
1952 png_error (png_ptr, "Palette is NULL in indexed image");
1953 }
1954 else
1955 {
1956 if (png_ptr->num_trans != 0)
1957 {
1958 if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
1959 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
1960 }
1961 if (info_ptr->bit_depth < 8)
1962 info_ptr->bit_depth = 8;
1963
1964 info_ptr->num_trans = 0;
1965 }
1966 }
1967 #endif
1968
1969 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
1970 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1971 /* The following is almost certainly wrong unless the background value is in
1972 * the screen space!
1973 */
1974 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1975 info_ptr->background = png_ptr->background;
1976 #endif
1977
1978 #ifdef PNG_READ_GAMMA_SUPPORTED
1979 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
1980 * however it seems that the code in png_init_read_transformations, which has
1981 * been called before this from png_read_update_info->png_read_start_row
1982 * sometimes does the gamma transform and cancels the flag.
1983 *
1984 * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
1985 * the screen_gamma value. The following probably results in weirdness if
1986 * the info_ptr is used by the app after the rows have been read.
1987 */
1988 info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
1989 #endif
1990
1991 if (info_ptr->bit_depth == 16)
1992 {
1993 # ifdef PNG_READ_16BIT_SUPPORTED
1994 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1995 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
1996 info_ptr->bit_depth = 8;
1997 # endif
1998
1999 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2000 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
2001 info_ptr->bit_depth = 8;
2002 # endif
2003
2004 # else
2005 /* No 16-bit support: force chopping 16-bit input down to 8, in this case
2006 * the app program can chose if both APIs are available by setting the
2007 * correct scaling to use.
2008 */
2009 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2010 /* For compatibility with previous versions use the strip method by
2011 * default. This code works because if PNG_SCALE_16_TO_8 is already
2012 * set the code below will do that in preference to the chop.
2013 */
2014 png_ptr->transformations |= PNG_16_TO_8;
2015 info_ptr->bit_depth = 8;
2016 # else
2017
2018 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2019 png_ptr->transformations |= PNG_SCALE_16_TO_8;
2020 info_ptr->bit_depth = 8;
2021 # else
2022
2023 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
2024 # endif
2025 # endif
2026 #endif /* !READ_16BIT */
2027 }
2028
2029 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2030 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
2031 info_ptr->color_type = (png_byte)(info_ptr->color_type |
2032 PNG_COLOR_MASK_COLOR);
2033 #endif
2034
2035 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2036 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
2037 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2038 ~PNG_COLOR_MASK_COLOR);
2039 #endif
2040
2041 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2042 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
2043 {
2044 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2045 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
2046 png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8)
2047 {
2048 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
2049 }
2050 }
2051 #endif
2052
2053 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2054 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
2055 info_ptr->bit_depth == 8 &&
2056 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
2057 {
2058 info_ptr->bit_depth = 16;
2059 }
2060 #endif
2061
2062 #ifdef PNG_READ_PACK_SUPPORTED
2063 if ((png_ptr->transformations & PNG_PACK) != 0 &&
2064 (info_ptr->bit_depth < 8))
2065 info_ptr->bit_depth = 8;
2066 #endif
2067
2068 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
2069 info_ptr->channels = 1;
2070
2071 else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
2072 info_ptr->channels = 3;
2073
2074 else
2075 info_ptr->channels = 1;
2076
2077 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2078 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0)
2079 {
2080 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2081 ~PNG_COLOR_MASK_ALPHA);
2082 info_ptr->num_trans = 0;
2083 }
2084 #endif
2085
2086 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
2087 info_ptr->channels++;
2088
2089 #ifdef PNG_READ_FILLER_SUPPORTED
2090 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2091 if ((png_ptr->transformations & PNG_FILLER) != 0 &&
2092 (info_ptr->color_type == PNG_COLOR_TYPE_RGB ||
2093 info_ptr->color_type == PNG_COLOR_TYPE_GRAY))
2094 {
2095 info_ptr->channels++;
2096 /* If adding a true alpha channel not just filler */
2097 if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0)
2098 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
2099 }
2100 #endif
2101
2102 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2103 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2104 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
2105 {
2106 if (png_ptr->user_transform_depth != 0)
2107 info_ptr->bit_depth = png_ptr->user_transform_depth;
2108
2109 if (png_ptr->user_transform_channels != 0)
2110 info_ptr->channels = png_ptr->user_transform_channels;
2111 }
2112 #endif
2113
2114 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
2115 info_ptr->bit_depth);
2116
2117 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
2118
2119 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2120 * check in png_rowbytes that the user buffer won't get overwritten. Note
2121 * that the field is not always set - if png_read_update_info isn't called
2122 * the application has to either not do any transforms or get the calculation
2123 * right itself.
2124 */
2125 png_ptr->info_rowbytes = info_ptr->rowbytes;
2126
2127 #ifndef PNG_READ_EXPAND_SUPPORTED
2128 if (png_ptr != NULL)
2129 return;
2130 #endif
2131 }
2132
2133 #ifdef PNG_READ_PACK_SUPPORTED
2134 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2135 * without changing the actual values. Thus, if you had a row with
2136 * a bit depth of 1, you would end up with bytes that only contained
2137 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2138 * png_do_shift() after this.
2139 */
2140 static void
png_do_unpack(png_row_infop row_info,png_bytep row)2141 png_do_unpack(png_row_infop row_info, png_bytep row)
2142 {
2143 png_debug(1, "in png_do_unpack");
2144
2145 if (row_info->bit_depth < 8)
2146 {
2147 png_uint_32 i;
2148 png_uint_32 row_width=row_info->width;
2149
2150 switch (row_info->bit_depth)
2151 {
2152 case 1:
2153 {
2154 png_bytep sp = row + (size_t)((row_width - 1) >> 3);
2155 png_bytep dp = row + (size_t)row_width - 1;
2156 png_uint_32 shift = 7U - ((row_width + 7U) & 0x07);
2157 for (i = 0; i < row_width; i++)
2158 {
2159 *dp = (png_byte)((*sp >> shift) & 0x01);
2160
2161 if (shift == 7)
2162 {
2163 shift = 0;
2164 sp--;
2165 }
2166
2167 else
2168 shift++;
2169
2170 dp--;
2171 }
2172 break;
2173 }
2174
2175 case 2:
2176 {
2177
2178 png_bytep sp = row + (size_t)((row_width - 1) >> 2);
2179 png_bytep dp = row + (size_t)row_width - 1;
2180 png_uint_32 shift = ((3U - ((row_width + 3U) & 0x03)) << 1);
2181 for (i = 0; i < row_width; i++)
2182 {
2183 *dp = (png_byte)((*sp >> shift) & 0x03);
2184
2185 if (shift == 6)
2186 {
2187 shift = 0;
2188 sp--;
2189 }
2190
2191 else
2192 shift += 2;
2193
2194 dp--;
2195 }
2196 break;
2197 }
2198
2199 case 4:
2200 {
2201 png_bytep sp = row + (size_t)((row_width - 1) >> 1);
2202 png_bytep dp = row + (size_t)row_width - 1;
2203 png_uint_32 shift = ((1U - ((row_width + 1U) & 0x01)) << 2);
2204 for (i = 0; i < row_width; i++)
2205 {
2206 *dp = (png_byte)((*sp >> shift) & 0x0f);
2207
2208 if (shift == 4)
2209 {
2210 shift = 0;
2211 sp--;
2212 }
2213
2214 else
2215 shift = 4;
2216
2217 dp--;
2218 }
2219 break;
2220 }
2221
2222 default:
2223 break;
2224 }
2225 row_info->bit_depth = 8;
2226 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2227 row_info->rowbytes = row_width * row_info->channels;
2228 }
2229 }
2230 #endif
2231
2232 #ifdef PNG_READ_SHIFT_SUPPORTED
2233 /* Reverse the effects of png_do_shift. This routine merely shifts the
2234 * pixels back to their significant bits values. Thus, if you have
2235 * a row of bit depth 8, but only 5 are significant, this will shift
2236 * the values back to 0 through 31.
2237 */
2238 static void
png_do_unshift(png_row_infop row_info,png_bytep row,png_const_color_8p sig_bits)2239 png_do_unshift(png_row_infop row_info, png_bytep row,
2240 png_const_color_8p sig_bits)
2241 {
2242 int color_type;
2243
2244 png_debug(1, "in png_do_unshift");
2245
2246 /* The palette case has already been handled in the _init routine. */
2247 color_type = row_info->color_type;
2248
2249 if (color_type != PNG_COLOR_TYPE_PALETTE)
2250 {
2251 int shift[4];
2252 int channels = 0;
2253 int bit_depth = row_info->bit_depth;
2254
2255 if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
2256 {
2257 shift[channels++] = bit_depth - sig_bits->red;
2258 shift[channels++] = bit_depth - sig_bits->green;
2259 shift[channels++] = bit_depth - sig_bits->blue;
2260 }
2261
2262 else
2263 {
2264 shift[channels++] = bit_depth - sig_bits->gray;
2265 }
2266
2267 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
2268 {
2269 shift[channels++] = bit_depth - sig_bits->alpha;
2270 }
2271
2272 {
2273 int c, have_shift;
2274
2275 for (c = have_shift = 0; c < channels; ++c)
2276 {
2277 /* A shift of more than the bit depth is an error condition but it
2278 * gets ignored here.
2279 */
2280 if (shift[c] <= 0 || shift[c] >= bit_depth)
2281 shift[c] = 0;
2282
2283 else
2284 have_shift = 1;
2285 }
2286
2287 if (have_shift == 0)
2288 return;
2289 }
2290
2291 switch (bit_depth)
2292 {
2293 default:
2294 /* Must be 1bpp gray: should not be here! */
2295 /* NOTREACHED */
2296 break;
2297
2298 case 2:
2299 /* Must be 2bpp gray */
2300 /* assert(channels == 1 && shift[0] == 1) */
2301 {
2302 png_bytep bp = row;
2303 png_bytep bp_end = bp + row_info->rowbytes;
2304
2305 while (bp < bp_end)
2306 {
2307 int b = (*bp >> 1) & 0x55;
2308 *bp++ = (png_byte)b;
2309 }
2310 break;
2311 }
2312
2313 case 4:
2314 /* Must be 4bpp gray */
2315 /* assert(channels == 1) */
2316 {
2317 png_bytep bp = row;
2318 png_bytep bp_end = bp + row_info->rowbytes;
2319 int gray_shift = shift[0];
2320 int mask = 0xf >> gray_shift;
2321
2322 mask |= mask << 4;
2323
2324 while (bp < bp_end)
2325 {
2326 int b = (*bp >> gray_shift) & mask;
2327 *bp++ = (png_byte)b;
2328 }
2329 break;
2330 }
2331
2332 case 8:
2333 /* Single byte components, G, GA, RGB, RGBA */
2334 {
2335 png_bytep bp = row;
2336 png_bytep bp_end = bp + row_info->rowbytes;
2337 int channel = 0;
2338
2339 while (bp < bp_end)
2340 {
2341 int b = *bp >> shift[channel];
2342 if (++channel >= channels)
2343 channel = 0;
2344 *bp++ = (png_byte)b;
2345 }
2346 break;
2347 }
2348
2349 #ifdef PNG_READ_16BIT_SUPPORTED
2350 case 16:
2351 /* Double byte components, G, GA, RGB, RGBA */
2352 {
2353 png_bytep bp = row;
2354 png_bytep bp_end = bp + row_info->rowbytes;
2355 int channel = 0;
2356
2357 while (bp < bp_end)
2358 {
2359 int value = (bp[0] << 8) + bp[1];
2360
2361 value >>= shift[channel];
2362 if (++channel >= channels)
2363 channel = 0;
2364 *bp++ = (png_byte)(value >> 8);
2365 *bp++ = (png_byte)value;
2366 }
2367 break;
2368 }
2369 #endif
2370 }
2371 }
2372 }
2373 #endif
2374
2375 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2376 /* Scale rows of bit depth 16 down to 8 accurately */
2377 static void
png_do_scale_16_to_8(png_row_infop row_info,png_bytep row)2378 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
2379 {
2380 png_debug(1, "in png_do_scale_16_to_8");
2381
2382 if (row_info->bit_depth == 16)
2383 {
2384 png_bytep sp = row; /* source */
2385 png_bytep dp = row; /* destination */
2386 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2387
2388 while (sp < ep)
2389 {
2390 /* The input is an array of 16-bit components, these must be scaled to
2391 * 8 bits each. For a 16-bit value V the required value (from the PNG
2392 * specification) is:
2393 *
2394 * (V * 255) / 65535
2395 *
2396 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2397 *
2398 * Represent V as the two byte value vhi.vlo. Make a guess that the
2399 * result is the top byte of V, vhi, then the correction to this value
2400 * is:
2401 *
2402 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2403 * = floor(((vlo-vhi) + 128.5) / 257)
2404 *
2405 * This can be approximated using integer arithmetic (and a signed
2406 * shift):
2407 *
2408 * error = (vlo-vhi+128) >> 8;
2409 *
2410 * The approximate differs from the exact answer only when (vlo-vhi) is
2411 * 128; it then gives a correction of +1 when the exact correction is
2412 * 0. This gives 128 errors. The exact answer (correct for all 16-bit
2413 * input values) is:
2414 *
2415 * error = (vlo-vhi+128)*65535 >> 24;
2416 *
2417 * An alternative arithmetic calculation which also gives no errors is:
2418 *
2419 * (V * 255 + 32895) >> 16
2420 */
2421
2422 png_int_32 tmp = *sp++; /* must be signed! */
2423 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
2424 *dp++ = (png_byte)tmp;
2425 }
2426
2427 row_info->bit_depth = 8;
2428 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2429 row_info->rowbytes = row_info->width * row_info->channels;
2430 }
2431 }
2432 #endif
2433
2434 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2435 static void
2436 /* Simply discard the low byte. This was the default behavior prior
2437 * to libpng-1.5.4.
2438 */
png_do_chop(png_row_infop row_info,png_bytep row)2439 png_do_chop(png_row_infop row_info, png_bytep row)
2440 {
2441 png_debug(1, "in png_do_chop");
2442
2443 if (row_info->bit_depth == 16)
2444 {
2445 png_bytep sp = row; /* source */
2446 png_bytep dp = row; /* destination */
2447 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2448
2449 while (sp < ep)
2450 {
2451 *dp++ = *sp;
2452 sp += 2; /* skip low byte */
2453 }
2454
2455 row_info->bit_depth = 8;
2456 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2457 row_info->rowbytes = row_info->width * row_info->channels;
2458 }
2459 }
2460 #endif
2461
2462 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2463 static void
png_do_read_swap_alpha(png_row_infop row_info,png_bytep row)2464 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
2465 {
2466 png_uint_32 row_width = row_info->width;
2467
2468 png_debug(1, "in png_do_read_swap_alpha");
2469
2470 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2471 {
2472 /* This converts from RGBA to ARGB */
2473 if (row_info->bit_depth == 8)
2474 {
2475 png_bytep sp = row + row_info->rowbytes;
2476 png_bytep dp = sp;
2477 png_byte save;
2478 png_uint_32 i;
2479
2480 for (i = 0; i < row_width; i++)
2481 {
2482 save = *(--sp);
2483 *(--dp) = *(--sp);
2484 *(--dp) = *(--sp);
2485 *(--dp) = *(--sp);
2486 *(--dp) = save;
2487 }
2488 }
2489
2490 #ifdef PNG_READ_16BIT_SUPPORTED
2491 /* This converts from RRGGBBAA to AARRGGBB */
2492 else
2493 {
2494 png_bytep sp = row + row_info->rowbytes;
2495 png_bytep dp = sp;
2496 png_byte save[2];
2497 png_uint_32 i;
2498
2499 for (i = 0; i < row_width; i++)
2500 {
2501 save[0] = *(--sp);
2502 save[1] = *(--sp);
2503 *(--dp) = *(--sp);
2504 *(--dp) = *(--sp);
2505 *(--dp) = *(--sp);
2506 *(--dp) = *(--sp);
2507 *(--dp) = *(--sp);
2508 *(--dp) = *(--sp);
2509 *(--dp) = save[0];
2510 *(--dp) = save[1];
2511 }
2512 }
2513 #endif
2514 }
2515
2516 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2517 {
2518 /* This converts from GA to AG */
2519 if (row_info->bit_depth == 8)
2520 {
2521 png_bytep sp = row + row_info->rowbytes;
2522 png_bytep dp = sp;
2523 png_byte save;
2524 png_uint_32 i;
2525
2526 for (i = 0; i < row_width; i++)
2527 {
2528 save = *(--sp);
2529 *(--dp) = *(--sp);
2530 *(--dp) = save;
2531 }
2532 }
2533
2534 #ifdef PNG_READ_16BIT_SUPPORTED
2535 /* This converts from GGAA to AAGG */
2536 else
2537 {
2538 png_bytep sp = row + row_info->rowbytes;
2539 png_bytep dp = sp;
2540 png_byte save[2];
2541 png_uint_32 i;
2542
2543 for (i = 0; i < row_width; i++)
2544 {
2545 save[0] = *(--sp);
2546 save[1] = *(--sp);
2547 *(--dp) = *(--sp);
2548 *(--dp) = *(--sp);
2549 *(--dp) = save[0];
2550 *(--dp) = save[1];
2551 }
2552 }
2553 #endif
2554 }
2555 }
2556 #endif
2557
2558 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2559 static void
png_do_read_invert_alpha(png_row_infop row_info,png_bytep row)2560 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
2561 {
2562 png_uint_32 row_width;
2563 png_debug(1, "in png_do_read_invert_alpha");
2564
2565 row_width = row_info->width;
2566 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2567 {
2568 if (row_info->bit_depth == 8)
2569 {
2570 /* This inverts the alpha channel in RGBA */
2571 png_bytep sp = row + row_info->rowbytes;
2572 png_bytep dp = sp;
2573 png_uint_32 i;
2574
2575 for (i = 0; i < row_width; i++)
2576 {
2577 *(--dp) = (png_byte)(255 - *(--sp));
2578
2579 /* This does nothing:
2580 *(--dp) = *(--sp);
2581 *(--dp) = *(--sp);
2582 *(--dp) = *(--sp);
2583 We can replace it with:
2584 */
2585 sp-=3;
2586 dp=sp;
2587 }
2588 }
2589
2590 #ifdef PNG_READ_16BIT_SUPPORTED
2591 /* This inverts the alpha channel in RRGGBBAA */
2592 else
2593 {
2594 png_bytep sp = row + row_info->rowbytes;
2595 png_bytep dp = sp;
2596 png_uint_32 i;
2597
2598 for (i = 0; i < row_width; i++)
2599 {
2600 *(--dp) = (png_byte)(255 - *(--sp));
2601 *(--dp) = (png_byte)(255 - *(--sp));
2602
2603 /* This does nothing:
2604 *(--dp) = *(--sp);
2605 *(--dp) = *(--sp);
2606 *(--dp) = *(--sp);
2607 *(--dp) = *(--sp);
2608 *(--dp) = *(--sp);
2609 *(--dp) = *(--sp);
2610 We can replace it with:
2611 */
2612 sp-=6;
2613 dp=sp;
2614 }
2615 }
2616 #endif
2617 }
2618 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2619 {
2620 if (row_info->bit_depth == 8)
2621 {
2622 /* This inverts the alpha channel in GA */
2623 png_bytep sp = row + row_info->rowbytes;
2624 png_bytep dp = sp;
2625 png_uint_32 i;
2626
2627 for (i = 0; i < row_width; i++)
2628 {
2629 *(--dp) = (png_byte)(255 - *(--sp));
2630 *(--dp) = *(--sp);
2631 }
2632 }
2633
2634 #ifdef PNG_READ_16BIT_SUPPORTED
2635 else
2636 {
2637 /* This inverts the alpha channel in GGAA */
2638 png_bytep sp = row + row_info->rowbytes;
2639 png_bytep dp = sp;
2640 png_uint_32 i;
2641
2642 for (i = 0; i < row_width; i++)
2643 {
2644 *(--dp) = (png_byte)(255 - *(--sp));
2645 *(--dp) = (png_byte)(255 - *(--sp));
2646 /*
2647 *(--dp) = *(--sp);
2648 *(--dp) = *(--sp);
2649 */
2650 sp-=2;
2651 dp=sp;
2652 }
2653 }
2654 #endif
2655 }
2656 }
2657 #endif
2658
2659 #ifdef PNG_READ_FILLER_SUPPORTED
2660 /* Add filler channel if we have RGB color */
2661 static void
png_do_read_filler(png_row_infop row_info,png_bytep row,png_uint_32 filler,png_uint_32 flags)2662 png_do_read_filler(png_row_infop row_info, png_bytep row,
2663 png_uint_32 filler, png_uint_32 flags)
2664 {
2665 png_uint_32 i;
2666 png_uint_32 row_width = row_info->width;
2667
2668 #ifdef PNG_READ_16BIT_SUPPORTED
2669 png_byte hi_filler = (png_byte)(filler>>8);
2670 #endif
2671 png_byte lo_filler = (png_byte)filler;
2672
2673 png_debug(1, "in png_do_read_filler");
2674
2675 if (
2676 row_info->color_type == PNG_COLOR_TYPE_GRAY)
2677 {
2678 if (row_info->bit_depth == 8)
2679 {
2680 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2681 {
2682 /* This changes the data from G to GX */
2683 png_bytep sp = row + (size_t)row_width;
2684 png_bytep dp = sp + (size_t)row_width;
2685 for (i = 1; i < row_width; i++)
2686 {
2687 *(--dp) = lo_filler;
2688 *(--dp) = *(--sp);
2689 }
2690 *(--dp) = lo_filler;
2691 row_info->channels = 2;
2692 row_info->pixel_depth = 16;
2693 row_info->rowbytes = row_width * 2;
2694 }
2695
2696 else
2697 {
2698 /* This changes the data from G to XG */
2699 png_bytep sp = row + (size_t)row_width;
2700 png_bytep dp = sp + (size_t)row_width;
2701 for (i = 0; i < row_width; i++)
2702 {
2703 *(--dp) = *(--sp);
2704 *(--dp) = lo_filler;
2705 }
2706 row_info->channels = 2;
2707 row_info->pixel_depth = 16;
2708 row_info->rowbytes = row_width * 2;
2709 }
2710 }
2711
2712 #ifdef PNG_READ_16BIT_SUPPORTED
2713 else if (row_info->bit_depth == 16)
2714 {
2715 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2716 {
2717 /* This changes the data from GG to GGXX */
2718 png_bytep sp = row + (size_t)row_width * 2;
2719 png_bytep dp = sp + (size_t)row_width * 2;
2720 for (i = 1; i < row_width; i++)
2721 {
2722 *(--dp) = lo_filler;
2723 *(--dp) = hi_filler;
2724 *(--dp) = *(--sp);
2725 *(--dp) = *(--sp);
2726 }
2727 *(--dp) = lo_filler;
2728 *(--dp) = hi_filler;
2729 row_info->channels = 2;
2730 row_info->pixel_depth = 32;
2731 row_info->rowbytes = row_width * 4;
2732 }
2733
2734 else
2735 {
2736 /* This changes the data from GG to XXGG */
2737 png_bytep sp = row + (size_t)row_width * 2;
2738 png_bytep dp = sp + (size_t)row_width * 2;
2739 for (i = 0; i < row_width; i++)
2740 {
2741 *(--dp) = *(--sp);
2742 *(--dp) = *(--sp);
2743 *(--dp) = lo_filler;
2744 *(--dp) = hi_filler;
2745 }
2746 row_info->channels = 2;
2747 row_info->pixel_depth = 32;
2748 row_info->rowbytes = row_width * 4;
2749 }
2750 }
2751 #endif
2752 } /* COLOR_TYPE == GRAY */
2753 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
2754 {
2755 if (row_info->bit_depth == 8)
2756 {
2757 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2758 {
2759 /* This changes the data from RGB to RGBX */
2760 png_bytep sp = row + (size_t)row_width * 3;
2761 png_bytep dp = sp + (size_t)row_width;
2762 for (i = 1; i < row_width; i++)
2763 {
2764 *(--dp) = lo_filler;
2765 *(--dp) = *(--sp);
2766 *(--dp) = *(--sp);
2767 *(--dp) = *(--sp);
2768 }
2769 *(--dp) = lo_filler;
2770 row_info->channels = 4;
2771 row_info->pixel_depth = 32;
2772 row_info->rowbytes = row_width * 4;
2773 }
2774
2775 else
2776 {
2777 /* This changes the data from RGB to XRGB */
2778 png_bytep sp = row + (size_t)row_width * 3;
2779 png_bytep dp = sp + (size_t)row_width;
2780 for (i = 0; i < row_width; i++)
2781 {
2782 *(--dp) = *(--sp);
2783 *(--dp) = *(--sp);
2784 *(--dp) = *(--sp);
2785 *(--dp) = lo_filler;
2786 }
2787 row_info->channels = 4;
2788 row_info->pixel_depth = 32;
2789 row_info->rowbytes = row_width * 4;
2790 }
2791 }
2792
2793 #ifdef PNG_READ_16BIT_SUPPORTED
2794 else if (row_info->bit_depth == 16)
2795 {
2796 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2797 {
2798 /* This changes the data from RRGGBB to RRGGBBXX */
2799 png_bytep sp = row + (size_t)row_width * 6;
2800 png_bytep dp = sp + (size_t)row_width * 2;
2801 for (i = 1; i < row_width; i++)
2802 {
2803 *(--dp) = lo_filler;
2804 *(--dp) = hi_filler;
2805 *(--dp) = *(--sp);
2806 *(--dp) = *(--sp);
2807 *(--dp) = *(--sp);
2808 *(--dp) = *(--sp);
2809 *(--dp) = *(--sp);
2810 *(--dp) = *(--sp);
2811 }
2812 *(--dp) = lo_filler;
2813 *(--dp) = hi_filler;
2814 row_info->channels = 4;
2815 row_info->pixel_depth = 64;
2816 row_info->rowbytes = row_width * 8;
2817 }
2818
2819 else
2820 {
2821 /* This changes the data from RRGGBB to XXRRGGBB */
2822 png_bytep sp = row + (size_t)row_width * 6;
2823 png_bytep dp = sp + (size_t)row_width * 2;
2824 for (i = 0; i < row_width; i++)
2825 {
2826 *(--dp) = *(--sp);
2827 *(--dp) = *(--sp);
2828 *(--dp) = *(--sp);
2829 *(--dp) = *(--sp);
2830 *(--dp) = *(--sp);
2831 *(--dp) = *(--sp);
2832 *(--dp) = lo_filler;
2833 *(--dp) = hi_filler;
2834 }
2835
2836 row_info->channels = 4;
2837 row_info->pixel_depth = 64;
2838 row_info->rowbytes = row_width * 8;
2839 }
2840 }
2841 #endif
2842 } /* COLOR_TYPE == RGB */
2843 }
2844 #endif
2845
2846 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2847 /* Expand grayscale files to RGB, with or without alpha */
2848 static void
png_do_gray_to_rgb(png_row_infop row_info,png_bytep row)2849 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
2850 {
2851 png_uint_32 i;
2852 png_uint_32 row_width = row_info->width;
2853
2854 png_debug(1, "in png_do_gray_to_rgb");
2855
2856 if (row_info->bit_depth >= 8 &&
2857 (row_info->color_type & PNG_COLOR_MASK_COLOR) == 0)
2858 {
2859 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
2860 {
2861 if (row_info->bit_depth == 8)
2862 {
2863 /* This changes G to RGB */
2864 png_bytep sp = row + (size_t)row_width - 1;
2865 png_bytep dp = sp + (size_t)row_width * 2;
2866 for (i = 0; i < row_width; i++)
2867 {
2868 *(dp--) = *sp;
2869 *(dp--) = *sp;
2870 *(dp--) = *(sp--);
2871 }
2872 }
2873
2874 else
2875 {
2876 /* This changes GG to RRGGBB */
2877 png_bytep sp = row + (size_t)row_width * 2 - 1;
2878 png_bytep dp = sp + (size_t)row_width * 4;
2879 for (i = 0; i < row_width; i++)
2880 {
2881 *(dp--) = *sp;
2882 *(dp--) = *(sp - 1);
2883 *(dp--) = *sp;
2884 *(dp--) = *(sp - 1);
2885 *(dp--) = *(sp--);
2886 *(dp--) = *(sp--);
2887 }
2888 }
2889 }
2890
2891 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2892 {
2893 if (row_info->bit_depth == 8)
2894 {
2895 /* This changes GA to RGBA */
2896 png_bytep sp = row + (size_t)row_width * 2 - 1;
2897 png_bytep dp = sp + (size_t)row_width * 2;
2898 for (i = 0; i < row_width; i++)
2899 {
2900 *(dp--) = *(sp--);
2901 *(dp--) = *sp;
2902 *(dp--) = *sp;
2903 *(dp--) = *(sp--);
2904 }
2905 }
2906
2907 else
2908 {
2909 /* This changes GGAA to RRGGBBAA */
2910 png_bytep sp = row + (size_t)row_width * 4 - 1;
2911 png_bytep dp = sp + (size_t)row_width * 4;
2912 for (i = 0; i < row_width; i++)
2913 {
2914 *(dp--) = *(sp--);
2915 *(dp--) = *(sp--);
2916 *(dp--) = *sp;
2917 *(dp--) = *(sp - 1);
2918 *(dp--) = *sp;
2919 *(dp--) = *(sp - 1);
2920 *(dp--) = *(sp--);
2921 *(dp--) = *(sp--);
2922 }
2923 }
2924 }
2925 row_info->channels = (png_byte)(row_info->channels + 2);
2926 row_info->color_type |= PNG_COLOR_MASK_COLOR;
2927 row_info->pixel_depth = (png_byte)(row_info->channels *
2928 row_info->bit_depth);
2929 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
2930 }
2931 }
2932 #endif
2933
2934 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2935 /* Reduce RGB files to grayscale, with or without alpha
2936 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
2937 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
2938 * versions dated 1998 through November 2002 have been archived at
2939 * https://web.archive.org/web/20000816232553/www.inforamp.net/
2940 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
2941 * Charles Poynton poynton at poynton.com
2942 *
2943 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
2944 *
2945 * which can be expressed with integers as
2946 *
2947 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
2948 *
2949 * Poynton's current link (as of January 2003 through July 2011):
2950 * <http://www.poynton.com/notes/colour_and_gamma/>
2951 * has changed the numbers slightly:
2952 *
2953 * Y = 0.2126*R + 0.7152*G + 0.0722*B
2954 *
2955 * which can be expressed with integers as
2956 *
2957 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
2958 *
2959 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
2960 * end point chromaticities and the D65 white point. Depending on the
2961 * precision used for the D65 white point this produces a variety of different
2962 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
2963 * used (0.3127,0.3290) the Y calculation would be:
2964 *
2965 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
2966 *
2967 * While this is correct the rounding results in an overflow for white, because
2968 * the sum of the rounded coefficients is 32769, not 32768. Consequently
2969 * libpng uses, instead, the closest non-overflowing approximation:
2970 *
2971 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
2972 *
2973 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
2974 * (including an sRGB chunk) then the chromaticities are used to calculate the
2975 * coefficients. See the chunk handling in pngrutil.c for more information.
2976 *
2977 * In all cases the calculation is to be done in a linear colorspace. If no
2978 * gamma information is available to correct the encoding of the original RGB
2979 * values this results in an implicit assumption that the original PNG RGB
2980 * values were linear.
2981 *
2982 * Other integer coefficients can be used via png_set_rgb_to_gray(). Because
2983 * the API takes just red and green coefficients the blue coefficient is
2984 * calculated to make the sum 32768. This will result in different rounding
2985 * to that used above.
2986 */
2987 static int
png_do_rgb_to_gray(png_structrp png_ptr,png_row_infop row_info,png_bytep row)2988 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
2989
2990 {
2991 int rgb_error = 0;
2992
2993 png_debug(1, "in png_do_rgb_to_gray");
2994
2995 if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
2996 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
2997 {
2998 PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
2999 PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
3000 PNG_CONST png_uint_32 bc = 32768 - rc - gc;
3001 PNG_CONST png_uint_32 row_width = row_info->width;
3002 PNG_CONST int have_alpha =
3003 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
3004
3005 if (row_info->bit_depth == 8)
3006 {
3007 #ifdef PNG_READ_GAMMA_SUPPORTED
3008 /* Notice that gamma to/from 1 are not necessarily inverses (if
3009 * there is an overall gamma correction). Prior to 1.5.5 this code
3010 * checked the linearized values for equality; this doesn't match
3011 * the documentation, the original values must be checked.
3012 */
3013 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
3014 {
3015 png_bytep sp = row;
3016 png_bytep dp = row;
3017 png_uint_32 i;
3018
3019 for (i = 0; i < row_width; i++)
3020 {
3021 png_byte red = *(sp++);
3022 png_byte green = *(sp++);
3023 png_byte blue = *(sp++);
3024
3025 if (red != green || red != blue)
3026 {
3027 red = png_ptr->gamma_to_1[red];
3028 green = png_ptr->gamma_to_1[green];
3029 blue = png_ptr->gamma_to_1[blue];
3030
3031 rgb_error |= 1;
3032 *(dp++) = png_ptr->gamma_from_1[
3033 (rc*red + gc*green + bc*blue + 16384)>>15];
3034 }
3035
3036 else
3037 {
3038 /* If there is no overall correction the table will not be
3039 * set.
3040 */
3041 if (png_ptr->gamma_table != NULL)
3042 red = png_ptr->gamma_table[red];
3043
3044 *(dp++) = red;
3045 }
3046
3047 if (have_alpha != 0)
3048 *(dp++) = *(sp++);
3049 }
3050 }
3051 else
3052 #endif
3053 {
3054 png_bytep sp = row;
3055 png_bytep dp = row;
3056 png_uint_32 i;
3057
3058 for (i = 0; i < row_width; i++)
3059 {
3060 png_byte red = *(sp++);
3061 png_byte green = *(sp++);
3062 png_byte blue = *(sp++);
3063
3064 if (red != green || red != blue)
3065 {
3066 rgb_error |= 1;
3067 /* NOTE: this is the historical approach which simply
3068 * truncates the results.
3069 */
3070 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
3071 }
3072
3073 else
3074 *(dp++) = red;
3075
3076 if (have_alpha != 0)
3077 *(dp++) = *(sp++);
3078 }
3079 }
3080 }
3081
3082 else /* RGB bit_depth == 16 */
3083 {
3084 #ifdef PNG_READ_GAMMA_SUPPORTED
3085 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
3086 {
3087 png_bytep sp = row;
3088 png_bytep dp = row;
3089 png_uint_32 i;
3090
3091 for (i = 0; i < row_width; i++)
3092 {
3093 png_uint_16 red, green, blue, w;
3094 png_byte hi,lo;
3095
3096 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3097 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3098 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3099
3100 if (red == green && red == blue)
3101 {
3102 if (png_ptr->gamma_16_table != NULL)
3103 w = png_ptr->gamma_16_table[(red & 0xff)
3104 >> png_ptr->gamma_shift][red >> 8];
3105
3106 else
3107 w = red;
3108 }
3109
3110 else
3111 {
3112 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red & 0xff)
3113 >> png_ptr->gamma_shift][red>>8];
3114 png_uint_16 green_1 =
3115 png_ptr->gamma_16_to_1[(green & 0xff) >>
3116 png_ptr->gamma_shift][green>>8];
3117 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue & 0xff)
3118 >> png_ptr->gamma_shift][blue>>8];
3119 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
3120 + bc*blue_1 + 16384)>>15);
3121 w = png_ptr->gamma_16_from_1[(gray16 & 0xff) >>
3122 png_ptr->gamma_shift][gray16 >> 8];
3123 rgb_error |= 1;
3124 }
3125
3126 *(dp++) = (png_byte)((w>>8) & 0xff);
3127 *(dp++) = (png_byte)(w & 0xff);
3128
3129 if (have_alpha != 0)
3130 {
3131 *(dp++) = *(sp++);
3132 *(dp++) = *(sp++);
3133 }
3134 }
3135 }
3136 else
3137 #endif
3138 {
3139 png_bytep sp = row;
3140 png_bytep dp = row;
3141 png_uint_32 i;
3142
3143 for (i = 0; i < row_width; i++)
3144 {
3145 png_uint_16 red, green, blue, gray16;
3146 png_byte hi,lo;
3147
3148 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3149 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3150 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3151
3152 if (red != green || red != blue)
3153 rgb_error |= 1;
3154
3155 /* From 1.5.5 in the 16-bit case do the accurate conversion even
3156 * in the 'fast' case - this is because this is where the code
3157 * ends up when handling linear 16-bit data.
3158 */
3159 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
3160 15);
3161 *(dp++) = (png_byte)((gray16 >> 8) & 0xff);
3162 *(dp++) = (png_byte)(gray16 & 0xff);
3163
3164 if (have_alpha != 0)
3165 {
3166 *(dp++) = *(sp++);
3167 *(dp++) = *(sp++);
3168 }
3169 }
3170 }
3171 }
3172
3173 row_info->channels = (png_byte)(row_info->channels - 2);
3174 row_info->color_type = (png_byte)(row_info->color_type &
3175 ~PNG_COLOR_MASK_COLOR);
3176 row_info->pixel_depth = (png_byte)(row_info->channels *
3177 row_info->bit_depth);
3178 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3179 }
3180 return rgb_error;
3181 }
3182 #endif
3183
3184 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
3185 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
3186 /* Replace any alpha or transparency with the supplied background color.
3187 * "background" is already in the screen gamma, while "background_1" is
3188 * at a gamma of 1.0. Paletted files have already been taken care of.
3189 */
3190 static void
png_do_compose(png_row_infop row_info,png_bytep row,png_structrp png_ptr)3191 png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3192 {
3193 #ifdef PNG_READ_GAMMA_SUPPORTED
3194 png_const_bytep gamma_table = png_ptr->gamma_table;
3195 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
3196 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
3197 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
3198 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
3199 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
3200 int gamma_shift = png_ptr->gamma_shift;
3201 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
3202 #endif
3203
3204 png_bytep sp;
3205 png_uint_32 i;
3206 png_uint_32 row_width = row_info->width;
3207 int shift;
3208
3209 png_debug(1, "in png_do_compose");
3210
3211 switch (row_info->color_type)
3212 {
3213 case PNG_COLOR_TYPE_GRAY:
3214 {
3215 switch (row_info->bit_depth)
3216 {
3217 case 1:
3218 {
3219 sp = row;
3220 shift = 7;
3221 for (i = 0; i < row_width; i++)
3222 {
3223 if ((png_uint_16)((*sp >> shift) & 0x01)
3224 == png_ptr->trans_color.gray)
3225 {
3226 unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
3227 tmp |=
3228 (unsigned int)(png_ptr->background.gray << shift);
3229 *sp = (png_byte)(tmp & 0xff);
3230 }
3231
3232 if (shift == 0)
3233 {
3234 shift = 7;
3235 sp++;
3236 }
3237
3238 else
3239 shift--;
3240 }
3241 break;
3242 }
3243
3244 case 2:
3245 {
3246 #ifdef PNG_READ_GAMMA_SUPPORTED
3247 if (gamma_table != NULL)
3248 {
3249 sp = row;
3250 shift = 6;
3251 for (i = 0; i < row_width; i++)
3252 {
3253 if ((png_uint_16)((*sp >> shift) & 0x03)
3254 == png_ptr->trans_color.gray)
3255 {
3256 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3257 tmp |=
3258 (unsigned int)png_ptr->background.gray << shift;
3259 *sp = (png_byte)(tmp & 0xff);
3260 }
3261
3262 else
3263 {
3264 unsigned int p = (*sp >> shift) & 0x03;
3265 unsigned int g = (gamma_table [p | (p << 2) |
3266 (p << 4) | (p << 6)] >> 6) & 0x03;
3267 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3268 tmp |= (unsigned int)(g << shift);
3269 *sp = (png_byte)(tmp & 0xff);
3270 }
3271
3272 if (shift == 0)
3273 {
3274 shift = 6;
3275 sp++;
3276 }
3277
3278 else
3279 shift -= 2;
3280 }
3281 }
3282
3283 else
3284 #endif
3285 {
3286 sp = row;
3287 shift = 6;
3288 for (i = 0; i < row_width; i++)
3289 {
3290 if ((png_uint_16)((*sp >> shift) & 0x03)
3291 == png_ptr->trans_color.gray)
3292 {
3293 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3294 tmp |=
3295 (unsigned int)png_ptr->background.gray << shift;
3296 *sp = (png_byte)(tmp & 0xff);
3297 }
3298
3299 if (shift == 0)
3300 {
3301 shift = 6;
3302 sp++;
3303 }
3304
3305 else
3306 shift -= 2;
3307 }
3308 }
3309 break;
3310 }
3311
3312 case 4:
3313 {
3314 #ifdef PNG_READ_GAMMA_SUPPORTED
3315 if (gamma_table != NULL)
3316 {
3317 sp = row;
3318 shift = 4;
3319 for (i = 0; i < row_width; i++)
3320 {
3321 if ((png_uint_16)((*sp >> shift) & 0x0f)
3322 == png_ptr->trans_color.gray)
3323 {
3324 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3325 tmp |=
3326 (unsigned int)(png_ptr->background.gray << shift);
3327 *sp = (png_byte)(tmp & 0xff);
3328 }
3329
3330 else
3331 {
3332 unsigned int p = (*sp >> shift) & 0x0f;
3333 unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
3334 0x0f;
3335 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3336 tmp |= (unsigned int)(g << shift);
3337 *sp = (png_byte)(tmp & 0xff);
3338 }
3339
3340 if (shift == 0)
3341 {
3342 shift = 4;
3343 sp++;
3344 }
3345
3346 else
3347 shift -= 4;
3348 }
3349 }
3350
3351 else
3352 #endif
3353 {
3354 sp = row;
3355 shift = 4;
3356 for (i = 0; i < row_width; i++)
3357 {
3358 if ((png_uint_16)((*sp >> shift) & 0x0f)
3359 == png_ptr->trans_color.gray)
3360 {
3361 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3362 tmp |=
3363 (unsigned int)(png_ptr->background.gray << shift);
3364 *sp = (png_byte)(tmp & 0xff);
3365 }
3366
3367 if (shift == 0)
3368 {
3369 shift = 4;
3370 sp++;
3371 }
3372
3373 else
3374 shift -= 4;
3375 }
3376 }
3377 break;
3378 }
3379
3380 case 8:
3381 {
3382 #ifdef PNG_READ_GAMMA_SUPPORTED
3383 if (gamma_table != NULL)
3384 {
3385 sp = row;
3386 for (i = 0; i < row_width; i++, sp++)
3387 {
3388 if (*sp == png_ptr->trans_color.gray)
3389 *sp = (png_byte)png_ptr->background.gray;
3390
3391 else
3392 *sp = gamma_table[*sp];
3393 }
3394 }
3395 else
3396 #endif
3397 {
3398 sp = row;
3399 for (i = 0; i < row_width; i++, sp++)
3400 {
3401 if (*sp == png_ptr->trans_color.gray)
3402 *sp = (png_byte)png_ptr->background.gray;
3403 }
3404 }
3405 break;
3406 }
3407
3408 case 16:
3409 {
3410 #ifdef PNG_READ_GAMMA_SUPPORTED
3411 if (gamma_16 != NULL)
3412 {
3413 sp = row;
3414 for (i = 0; i < row_width; i++, sp += 2)
3415 {
3416 png_uint_16 v;
3417
3418 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3419
3420 if (v == png_ptr->trans_color.gray)
3421 {
3422 /* Background is already in screen gamma */
3423 *sp = (png_byte)((png_ptr->background.gray >> 8)
3424 & 0xff);
3425 *(sp + 1) = (png_byte)(png_ptr->background.gray
3426 & 0xff);
3427 }
3428
3429 else
3430 {
3431 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3432 *sp = (png_byte)((v >> 8) & 0xff);
3433 *(sp + 1) = (png_byte)(v & 0xff);
3434 }
3435 }
3436 }
3437 else
3438 #endif
3439 {
3440 sp = row;
3441 for (i = 0; i < row_width; i++, sp += 2)
3442 {
3443 png_uint_16 v;
3444
3445 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3446
3447 if (v == png_ptr->trans_color.gray)
3448 {
3449 *sp = (png_byte)((png_ptr->background.gray >> 8)
3450 & 0xff);
3451 *(sp + 1) = (png_byte)(png_ptr->background.gray
3452 & 0xff);
3453 }
3454 }
3455 }
3456 break;
3457 }
3458
3459 default:
3460 break;
3461 }
3462 break;
3463 }
3464
3465 case PNG_COLOR_TYPE_RGB:
3466 {
3467 if (row_info->bit_depth == 8)
3468 {
3469 #ifdef PNG_READ_GAMMA_SUPPORTED
3470 if (gamma_table != NULL)
3471 {
3472 sp = row;
3473 for (i = 0; i < row_width; i++, sp += 3)
3474 {
3475 if (*sp == png_ptr->trans_color.red &&
3476 *(sp + 1) == png_ptr->trans_color.green &&
3477 *(sp + 2) == png_ptr->trans_color.blue)
3478 {
3479 *sp = (png_byte)png_ptr->background.red;
3480 *(sp + 1) = (png_byte)png_ptr->background.green;
3481 *(sp + 2) = (png_byte)png_ptr->background.blue;
3482 }
3483
3484 else
3485 {
3486 *sp = gamma_table[*sp];
3487 *(sp + 1) = gamma_table[*(sp + 1)];
3488 *(sp + 2) = gamma_table[*(sp + 2)];
3489 }
3490 }
3491 }
3492 else
3493 #endif
3494 {
3495 sp = row;
3496 for (i = 0; i < row_width; i++, sp += 3)
3497 {
3498 if (*sp == png_ptr->trans_color.red &&
3499 *(sp + 1) == png_ptr->trans_color.green &&
3500 *(sp + 2) == png_ptr->trans_color.blue)
3501 {
3502 *sp = (png_byte)png_ptr->background.red;
3503 *(sp + 1) = (png_byte)png_ptr->background.green;
3504 *(sp + 2) = (png_byte)png_ptr->background.blue;
3505 }
3506 }
3507 }
3508 }
3509 else /* if (row_info->bit_depth == 16) */
3510 {
3511 #ifdef PNG_READ_GAMMA_SUPPORTED
3512 if (gamma_16 != NULL)
3513 {
3514 sp = row;
3515 for (i = 0; i < row_width; i++, sp += 6)
3516 {
3517 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3518
3519 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3520 + *(sp + 3));
3521
3522 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3523 + *(sp + 5));
3524
3525 if (r == png_ptr->trans_color.red &&
3526 g == png_ptr->trans_color.green &&
3527 b == png_ptr->trans_color.blue)
3528 {
3529 /* Background is already in screen gamma */
3530 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3531 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3532 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3533 & 0xff);
3534 *(sp + 3) = (png_byte)(png_ptr->background.green
3535 & 0xff);
3536 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3537 & 0xff);
3538 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3539 }
3540
3541 else
3542 {
3543 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3544 *sp = (png_byte)((v >> 8) & 0xff);
3545 *(sp + 1) = (png_byte)(v & 0xff);
3546
3547 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3548 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3549 *(sp + 3) = (png_byte)(v & 0xff);
3550
3551 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3552 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3553 *(sp + 5) = (png_byte)(v & 0xff);
3554 }
3555 }
3556 }
3557
3558 else
3559 #endif
3560 {
3561 sp = row;
3562 for (i = 0; i < row_width; i++, sp += 6)
3563 {
3564 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3565
3566 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3567 + *(sp + 3));
3568
3569 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3570 + *(sp + 5));
3571
3572 if (r == png_ptr->trans_color.red &&
3573 g == png_ptr->trans_color.green &&
3574 b == png_ptr->trans_color.blue)
3575 {
3576 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3577 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3578 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3579 & 0xff);
3580 *(sp + 3) = (png_byte)(png_ptr->background.green
3581 & 0xff);
3582 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3583 & 0xff);
3584 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3585 }
3586 }
3587 }
3588 }
3589 break;
3590 }
3591
3592 case PNG_COLOR_TYPE_GRAY_ALPHA:
3593 {
3594 if (row_info->bit_depth == 8)
3595 {
3596 #ifdef PNG_READ_GAMMA_SUPPORTED
3597 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3598 gamma_table != NULL)
3599 {
3600 sp = row;
3601 for (i = 0; i < row_width; i++, sp += 2)
3602 {
3603 png_uint_16 a = *(sp + 1);
3604
3605 if (a == 0xff)
3606 *sp = gamma_table[*sp];
3607
3608 else if (a == 0)
3609 {
3610 /* Background is already in screen gamma */
3611 *sp = (png_byte)png_ptr->background.gray;
3612 }
3613
3614 else
3615 {
3616 png_byte v, w;
3617
3618 v = gamma_to_1[*sp];
3619 png_composite(w, v, a, png_ptr->background_1.gray);
3620 if (optimize == 0)
3621 w = gamma_from_1[w];
3622 *sp = w;
3623 }
3624 }
3625 }
3626 else
3627 #endif
3628 {
3629 sp = row;
3630 for (i = 0; i < row_width; i++, sp += 2)
3631 {
3632 png_byte a = *(sp + 1);
3633
3634 if (a == 0)
3635 *sp = (png_byte)png_ptr->background.gray;
3636
3637 else if (a < 0xff)
3638 png_composite(*sp, *sp, a, png_ptr->background.gray);
3639 }
3640 }
3641 }
3642 else /* if (png_ptr->bit_depth == 16) */
3643 {
3644 #ifdef PNG_READ_GAMMA_SUPPORTED
3645 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3646 gamma_16_to_1 != NULL)
3647 {
3648 sp = row;
3649 for (i = 0; i < row_width; i++, sp += 4)
3650 {
3651 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3652 + *(sp + 3));
3653
3654 if (a == (png_uint_16)0xffff)
3655 {
3656 png_uint_16 v;
3657
3658 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3659 *sp = (png_byte)((v >> 8) & 0xff);
3660 *(sp + 1) = (png_byte)(v & 0xff);
3661 }
3662
3663 else if (a == 0)
3664 {
3665 /* Background is already in screen gamma */
3666 *sp = (png_byte)((png_ptr->background.gray >> 8)
3667 & 0xff);
3668 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3669 }
3670
3671 else
3672 {
3673 png_uint_16 g, v, w;
3674
3675 g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3676 png_composite_16(v, g, a, png_ptr->background_1.gray);
3677 if (optimize != 0)
3678 w = v;
3679 else
3680 w = gamma_16_from_1[(v & 0xff) >>
3681 gamma_shift][v >> 8];
3682 *sp = (png_byte)((w >> 8) & 0xff);
3683 *(sp + 1) = (png_byte)(w & 0xff);
3684 }
3685 }
3686 }
3687 else
3688 #endif
3689 {
3690 sp = row;
3691 for (i = 0; i < row_width; i++, sp += 4)
3692 {
3693 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3694 + *(sp + 3));
3695
3696 if (a == 0)
3697 {
3698 *sp = (png_byte)((png_ptr->background.gray >> 8)
3699 & 0xff);
3700 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3701 }
3702
3703 else if (a < 0xffff)
3704 {
3705 png_uint_16 g, v;
3706
3707 g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3708 png_composite_16(v, g, a, png_ptr->background.gray);
3709 *sp = (png_byte)((v >> 8) & 0xff);
3710 *(sp + 1) = (png_byte)(v & 0xff);
3711 }
3712 }
3713 }
3714 }
3715 break;
3716 }
3717
3718 case PNG_COLOR_TYPE_RGB_ALPHA:
3719 {
3720 if (row_info->bit_depth == 8)
3721 {
3722 #ifdef PNG_READ_GAMMA_SUPPORTED
3723 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3724 gamma_table != NULL)
3725 {
3726 sp = row;
3727 for (i = 0; i < row_width; i++, sp += 4)
3728 {
3729 png_byte a = *(sp + 3);
3730
3731 if (a == 0xff)
3732 {
3733 *sp = gamma_table[*sp];
3734 *(sp + 1) = gamma_table[*(sp + 1)];
3735 *(sp + 2) = gamma_table[*(sp + 2)];
3736 }
3737
3738 else if (a == 0)
3739 {
3740 /* Background is already in screen gamma */
3741 *sp = (png_byte)png_ptr->background.red;
3742 *(sp + 1) = (png_byte)png_ptr->background.green;
3743 *(sp + 2) = (png_byte)png_ptr->background.blue;
3744 }
3745
3746 else
3747 {
3748 png_byte v, w;
3749
3750 v = gamma_to_1[*sp];
3751 png_composite(w, v, a, png_ptr->background_1.red);
3752 if (optimize == 0) w = gamma_from_1[w];
3753 *sp = w;
3754
3755 v = gamma_to_1[*(sp + 1)];
3756 png_composite(w, v, a, png_ptr->background_1.green);
3757 if (optimize == 0) w = gamma_from_1[w];
3758 *(sp + 1) = w;
3759
3760 v = gamma_to_1[*(sp + 2)];
3761 png_composite(w, v, a, png_ptr->background_1.blue);
3762 if (optimize == 0) w = gamma_from_1[w];
3763 *(sp + 2) = w;
3764 }
3765 }
3766 }
3767 else
3768 #endif
3769 {
3770 sp = row;
3771 for (i = 0; i < row_width; i++, sp += 4)
3772 {
3773 png_byte a = *(sp + 3);
3774
3775 if (a == 0)
3776 {
3777 *sp = (png_byte)png_ptr->background.red;
3778 *(sp + 1) = (png_byte)png_ptr->background.green;
3779 *(sp + 2) = (png_byte)png_ptr->background.blue;
3780 }
3781
3782 else if (a < 0xff)
3783 {
3784 png_composite(*sp, *sp, a, png_ptr->background.red);
3785
3786 png_composite(*(sp + 1), *(sp + 1), a,
3787 png_ptr->background.green);
3788
3789 png_composite(*(sp + 2), *(sp + 2), a,
3790 png_ptr->background.blue);
3791 }
3792 }
3793 }
3794 }
3795 else /* if (row_info->bit_depth == 16) */
3796 {
3797 #ifdef PNG_READ_GAMMA_SUPPORTED
3798 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3799 gamma_16_to_1 != NULL)
3800 {
3801 sp = row;
3802 for (i = 0; i < row_width; i++, sp += 8)
3803 {
3804 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3805 << 8) + (png_uint_16)(*(sp + 7)));
3806
3807 if (a == (png_uint_16)0xffff)
3808 {
3809 png_uint_16 v;
3810
3811 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3812 *sp = (png_byte)((v >> 8) & 0xff);
3813 *(sp + 1) = (png_byte)(v & 0xff);
3814
3815 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3816 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3817 *(sp + 3) = (png_byte)(v & 0xff);
3818
3819 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3820 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3821 *(sp + 5) = (png_byte)(v & 0xff);
3822 }
3823
3824 else if (a == 0)
3825 {
3826 /* Background is already in screen gamma */
3827 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3828 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3829 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3830 & 0xff);
3831 *(sp + 3) = (png_byte)(png_ptr->background.green
3832 & 0xff);
3833 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3834 & 0xff);
3835 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3836 }
3837
3838 else
3839 {
3840 png_uint_16 v, w;
3841
3842 v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3843 png_composite_16(w, v, a, png_ptr->background_1.red);
3844 if (optimize == 0)
3845 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3846 8];
3847 *sp = (png_byte)((w >> 8) & 0xff);
3848 *(sp + 1) = (png_byte)(w & 0xff);
3849
3850 v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
3851 png_composite_16(w, v, a, png_ptr->background_1.green);
3852 if (optimize == 0)
3853 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3854 8];
3855
3856 *(sp + 2) = (png_byte)((w >> 8) & 0xff);
3857 *(sp + 3) = (png_byte)(w & 0xff);
3858
3859 v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
3860 png_composite_16(w, v, a, png_ptr->background_1.blue);
3861 if (optimize == 0)
3862 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3863 8];
3864
3865 *(sp + 4) = (png_byte)((w >> 8) & 0xff);
3866 *(sp + 5) = (png_byte)(w & 0xff);
3867 }
3868 }
3869 }
3870
3871 else
3872 #endif
3873 {
3874 sp = row;
3875 for (i = 0; i < row_width; i++, sp += 8)
3876 {
3877 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3878 << 8) + (png_uint_16)(*(sp + 7)));
3879
3880 if (a == 0)
3881 {
3882 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3883 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3884 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3885 & 0xff);
3886 *(sp + 3) = (png_byte)(png_ptr->background.green
3887 & 0xff);
3888 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3889 & 0xff);
3890 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3891 }
3892
3893 else if (a < 0xffff)
3894 {
3895 png_uint_16 v;
3896
3897 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3898 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3899 + *(sp + 3));
3900 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3901 + *(sp + 5));
3902
3903 png_composite_16(v, r, a, png_ptr->background.red);
3904 *sp = (png_byte)((v >> 8) & 0xff);
3905 *(sp + 1) = (png_byte)(v & 0xff);
3906
3907 png_composite_16(v, g, a, png_ptr->background.green);
3908 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3909 *(sp + 3) = (png_byte)(v & 0xff);
3910
3911 png_composite_16(v, b, a, png_ptr->background.blue);
3912 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3913 *(sp + 5) = (png_byte)(v & 0xff);
3914 }
3915 }
3916 }
3917 }
3918 break;
3919 }
3920
3921 default:
3922 break;
3923 }
3924 }
3925 #endif /* READ_BACKGROUND || READ_ALPHA_MODE */
3926
3927 #ifdef PNG_READ_GAMMA_SUPPORTED
3928 /* Gamma correct the image, avoiding the alpha channel. Make sure
3929 * you do this after you deal with the transparency issue on grayscale
3930 * or RGB images. If your bit depth is 8, use gamma_table, if it
3931 * is 16, use gamma_16_table and gamma_shift. Build these with
3932 * build_gamma_table().
3933 */
3934 static void
png_do_gamma(png_row_infop row_info,png_bytep row,png_structrp png_ptr)3935 png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3936 {
3937 png_const_bytep gamma_table = png_ptr->gamma_table;
3938 png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
3939 int gamma_shift = png_ptr->gamma_shift;
3940
3941 png_bytep sp;
3942 png_uint_32 i;
3943 png_uint_32 row_width=row_info->width;
3944
3945 png_debug(1, "in png_do_gamma");
3946
3947 if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
3948 (row_info->bit_depth == 16 && gamma_16_table != NULL)))
3949 {
3950 switch (row_info->color_type)
3951 {
3952 case PNG_COLOR_TYPE_RGB:
3953 {
3954 if (row_info->bit_depth == 8)
3955 {
3956 sp = row;
3957 for (i = 0; i < row_width; i++)
3958 {
3959 *sp = gamma_table[*sp];
3960 sp++;
3961 *sp = gamma_table[*sp];
3962 sp++;
3963 *sp = gamma_table[*sp];
3964 sp++;
3965 }
3966 }
3967
3968 else /* if (row_info->bit_depth == 16) */
3969 {
3970 sp = row;
3971 for (i = 0; i < row_width; i++)
3972 {
3973 png_uint_16 v;
3974
3975 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
3976 *sp = (png_byte)((v >> 8) & 0xff);
3977 *(sp + 1) = (png_byte)(v & 0xff);
3978 sp += 2;
3979
3980 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
3981 *sp = (png_byte)((v >> 8) & 0xff);
3982 *(sp + 1) = (png_byte)(v & 0xff);
3983 sp += 2;
3984
3985 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
3986 *sp = (png_byte)((v >> 8) & 0xff);
3987 *(sp + 1) = (png_byte)(v & 0xff);
3988 sp += 2;
3989 }
3990 }
3991 break;
3992 }
3993
3994 case PNG_COLOR_TYPE_RGB_ALPHA:
3995 {
3996 if (row_info->bit_depth == 8)
3997 {
3998 sp = row;
3999 for (i = 0; i < row_width; i++)
4000 {
4001 *sp = gamma_table[*sp];
4002 sp++;
4003
4004 *sp = gamma_table[*sp];
4005 sp++;
4006
4007 *sp = gamma_table[*sp];
4008 sp++;
4009
4010 sp++;
4011 }
4012 }
4013
4014 else /* if (row_info->bit_depth == 16) */
4015 {
4016 sp = row;
4017 for (i = 0; i < row_width; i++)
4018 {
4019 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4020 *sp = (png_byte)((v >> 8) & 0xff);
4021 *(sp + 1) = (png_byte)(v & 0xff);
4022 sp += 2;
4023
4024 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4025 *sp = (png_byte)((v >> 8) & 0xff);
4026 *(sp + 1) = (png_byte)(v & 0xff);
4027 sp += 2;
4028
4029 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4030 *sp = (png_byte)((v >> 8) & 0xff);
4031 *(sp + 1) = (png_byte)(v & 0xff);
4032 sp += 4;
4033 }
4034 }
4035 break;
4036 }
4037
4038 case PNG_COLOR_TYPE_GRAY_ALPHA:
4039 {
4040 if (row_info->bit_depth == 8)
4041 {
4042 sp = row;
4043 for (i = 0; i < row_width; i++)
4044 {
4045 *sp = gamma_table[*sp];
4046 sp += 2;
4047 }
4048 }
4049
4050 else /* if (row_info->bit_depth == 16) */
4051 {
4052 sp = row;
4053 for (i = 0; i < row_width; i++)
4054 {
4055 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4056 *sp = (png_byte)((v >> 8) & 0xff);
4057 *(sp + 1) = (png_byte)(v & 0xff);
4058 sp += 4;
4059 }
4060 }
4061 break;
4062 }
4063
4064 case PNG_COLOR_TYPE_GRAY:
4065 {
4066 if (row_info->bit_depth == 2)
4067 {
4068 sp = row;
4069 for (i = 0; i < row_width; i += 4)
4070 {
4071 int a = *sp & 0xc0;
4072 int b = *sp & 0x30;
4073 int c = *sp & 0x0c;
4074 int d = *sp & 0x03;
4075
4076 *sp = (png_byte)(
4077 ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)|
4078 ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
4079 ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
4080 ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
4081 sp++;
4082 }
4083 }
4084
4085 if (row_info->bit_depth == 4)
4086 {
4087 sp = row;
4088 for (i = 0; i < row_width; i += 2)
4089 {
4090 int msb = *sp & 0xf0;
4091 int lsb = *sp & 0x0f;
4092
4093 *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
4094 | (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
4095 sp++;
4096 }
4097 }
4098
4099 else if (row_info->bit_depth == 8)
4100 {
4101 sp = row;
4102 for (i = 0; i < row_width; i++)
4103 {
4104 *sp = gamma_table[*sp];
4105 sp++;
4106 }
4107 }
4108
4109 else if (row_info->bit_depth == 16)
4110 {
4111 sp = row;
4112 for (i = 0; i < row_width; i++)
4113 {
4114 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4115 *sp = (png_byte)((v >> 8) & 0xff);
4116 *(sp + 1) = (png_byte)(v & 0xff);
4117 sp += 2;
4118 }
4119 }
4120 break;
4121 }
4122
4123 default:
4124 break;
4125 }
4126 }
4127 }
4128 #endif
4129
4130 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4131 /* Encode the alpha channel to the output gamma (the input channel is always
4132 * linear.) Called only with color types that have an alpha channel. Needs the
4133 * from_1 tables.
4134 */
4135 static void
png_do_encode_alpha(png_row_infop row_info,png_bytep row,png_structrp png_ptr)4136 png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
4137 {
4138 png_uint_32 row_width = row_info->width;
4139
4140 png_debug(1, "in png_do_encode_alpha");
4141
4142 if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4143 {
4144 if (row_info->bit_depth == 8)
4145 {
4146 PNG_CONST png_bytep table = png_ptr->gamma_from_1;
4147
4148 if (table != NULL)
4149 {
4150 PNG_CONST int step =
4151 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
4152
4153 /* The alpha channel is the last component: */
4154 row += step - 1;
4155
4156 for (; row_width > 0; --row_width, row += step)
4157 *row = table[*row];
4158
4159 return;
4160 }
4161 }
4162
4163 else if (row_info->bit_depth == 16)
4164 {
4165 PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1;
4166 PNG_CONST int gamma_shift = png_ptr->gamma_shift;
4167
4168 if (table != NULL)
4169 {
4170 PNG_CONST int step =
4171 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
4172
4173 /* The alpha channel is the last component: */
4174 row += step - 2;
4175
4176 for (; row_width > 0; --row_width, row += step)
4177 {
4178 png_uint_16 v;
4179
4180 v = table[*(row + 1) >> gamma_shift][*row];
4181 *row = (png_byte)((v >> 8) & 0xff);
4182 *(row + 1) = (png_byte)(v & 0xff);
4183 }
4184
4185 return;
4186 }
4187 }
4188 }
4189
4190 /* Only get to here if called with a weird row_info; no harm has been done,
4191 * so just issue a warning.
4192 */
4193 png_warning(png_ptr, "png_do_encode_alpha: unexpected call");
4194 }
4195 #endif
4196
4197 #ifdef PNG_READ_EXPAND_SUPPORTED
4198 /* Expands a palette row to an RGB or RGBA row depending
4199 * upon whether you supply trans and num_trans.
4200 */
4201 static void
png_do_expand_palette(png_row_infop row_info,png_bytep row,png_const_colorp palette,png_const_bytep trans_alpha,int num_trans)4202 png_do_expand_palette(png_row_infop row_info, png_bytep row,
4203 png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
4204 {
4205 int shift, value;
4206 png_bytep sp, dp;
4207 png_uint_32 i;
4208 png_uint_32 row_width=row_info->width;
4209
4210 png_debug(1, "in png_do_expand_palette");
4211
4212 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4213 {
4214 if (row_info->bit_depth < 8)
4215 {
4216 switch (row_info->bit_depth)
4217 {
4218 case 1:
4219 {
4220 sp = row + (size_t)((row_width - 1) >> 3);
4221 dp = row + (size_t)row_width - 1;
4222 shift = 7 - (int)((row_width + 7) & 0x07);
4223 for (i = 0; i < row_width; i++)
4224 {
4225 if ((*sp >> shift) & 0x01)
4226 *dp = 1;
4227
4228 else
4229 *dp = 0;
4230
4231 if (shift == 7)
4232 {
4233 shift = 0;
4234 sp--;
4235 }
4236
4237 else
4238 shift++;
4239
4240 dp--;
4241 }
4242 break;
4243 }
4244
4245 case 2:
4246 {
4247 sp = row + (size_t)((row_width - 1) >> 2);
4248 dp = row + (size_t)row_width - 1;
4249 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4250 for (i = 0; i < row_width; i++)
4251 {
4252 value = (*sp >> shift) & 0x03;
4253 *dp = (png_byte)value;
4254 if (shift == 6)
4255 {
4256 shift = 0;
4257 sp--;
4258 }
4259
4260 else
4261 shift += 2;
4262
4263 dp--;
4264 }
4265 break;
4266 }
4267
4268 case 4:
4269 {
4270 sp = row + (size_t)((row_width - 1) >> 1);
4271 dp = row + (size_t)row_width - 1;
4272 shift = (int)((row_width & 0x01) << 2);
4273 for (i = 0; i < row_width; i++)
4274 {
4275 value = (*sp >> shift) & 0x0f;
4276 *dp = (png_byte)value;
4277 if (shift == 4)
4278 {
4279 shift = 0;
4280 sp--;
4281 }
4282
4283 else
4284 shift += 4;
4285
4286 dp--;
4287 }
4288 break;
4289 }
4290
4291 default:
4292 break;
4293 }
4294 row_info->bit_depth = 8;
4295 row_info->pixel_depth = 8;
4296 row_info->rowbytes = row_width;
4297 }
4298
4299 if (row_info->bit_depth == 8)
4300 {
4301 {
4302 if (num_trans > 0)
4303 {
4304 sp = row + (size_t)row_width - 1;
4305 dp = row + ((size_t)row_width << 2) - 1;
4306
4307 for (i = 0; i < row_width; i++)
4308 {
4309 if ((int)(*sp) >= num_trans)
4310 *dp-- = 0xff;
4311
4312 else
4313 *dp-- = trans_alpha[*sp];
4314
4315 *dp-- = palette[*sp].blue;
4316 *dp-- = palette[*sp].green;
4317 *dp-- = palette[*sp].red;
4318 sp--;
4319 }
4320 row_info->bit_depth = 8;
4321 row_info->pixel_depth = 32;
4322 row_info->rowbytes = row_width * 4;
4323 row_info->color_type = 6;
4324 row_info->channels = 4;
4325 }
4326
4327 else
4328 {
4329 sp = row + (size_t)row_width - 1;
4330 dp = row + (size_t)(row_width * 3) - 1;
4331
4332 for (i = 0; i < row_width; i++)
4333 {
4334 *dp-- = palette[*sp].blue;
4335 *dp-- = palette[*sp].green;
4336 *dp-- = palette[*sp].red;
4337 sp--;
4338 }
4339
4340 row_info->bit_depth = 8;
4341 row_info->pixel_depth = 24;
4342 row_info->rowbytes = row_width * 3;
4343 row_info->color_type = 2;
4344 row_info->channels = 3;
4345 }
4346 }
4347 }
4348 }
4349 }
4350
4351 /* If the bit depth < 8, it is expanded to 8. Also, if the already
4352 * expanded transparency value is supplied, an alpha channel is built.
4353 */
4354 static void
png_do_expand(png_row_infop row_info,png_bytep row,png_const_color_16p trans_color)4355 png_do_expand(png_row_infop row_info, png_bytep row,
4356 png_const_color_16p trans_color)
4357 {
4358 int shift, value;
4359 png_bytep sp, dp;
4360 png_uint_32 i;
4361 png_uint_32 row_width=row_info->width;
4362
4363 png_debug(1, "in png_do_expand");
4364
4365 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
4366 {
4367 unsigned int gray = trans_color != NULL ? trans_color->gray : 0;
4368
4369 if (row_info->bit_depth < 8)
4370 {
4371 switch (row_info->bit_depth)
4372 {
4373 case 1:
4374 {
4375 gray = (gray & 0x01) * 0xff;
4376 sp = row + (size_t)((row_width - 1) >> 3);
4377 dp = row + (size_t)row_width - 1;
4378 shift = 7 - (int)((row_width + 7) & 0x07);
4379 for (i = 0; i < row_width; i++)
4380 {
4381 if ((*sp >> shift) & 0x01)
4382 *dp = 0xff;
4383
4384 else
4385 *dp = 0;
4386
4387 if (shift == 7)
4388 {
4389 shift = 0;
4390 sp--;
4391 }
4392
4393 else
4394 shift++;
4395
4396 dp--;
4397 }
4398 break;
4399 }
4400
4401 case 2:
4402 {
4403 gray = (gray & 0x03) * 0x55;
4404 sp = row + (size_t)((row_width - 1) >> 2);
4405 dp = row + (size_t)row_width - 1;
4406 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4407 for (i = 0; i < row_width; i++)
4408 {
4409 value = (*sp >> shift) & 0x03;
4410 *dp = (png_byte)(value | (value << 2) | (value << 4) |
4411 (value << 6));
4412 if (shift == 6)
4413 {
4414 shift = 0;
4415 sp--;
4416 }
4417
4418 else
4419 shift += 2;
4420
4421 dp--;
4422 }
4423 break;
4424 }
4425
4426 case 4:
4427 {
4428 gray = (gray & 0x0f) * 0x11;
4429 sp = row + (size_t)((row_width - 1) >> 1);
4430 dp = row + (size_t)row_width - 1;
4431 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
4432 for (i = 0; i < row_width; i++)
4433 {
4434 value = (*sp >> shift) & 0x0f;
4435 *dp = (png_byte)(value | (value << 4));
4436 if (shift == 4)
4437 {
4438 shift = 0;
4439 sp--;
4440 }
4441
4442 else
4443 shift = 4;
4444
4445 dp--;
4446 }
4447 break;
4448 }
4449
4450 default:
4451 break;
4452 }
4453
4454 row_info->bit_depth = 8;
4455 row_info->pixel_depth = 8;
4456 row_info->rowbytes = row_width;
4457 }
4458
4459 if (trans_color != NULL)
4460 {
4461 if (row_info->bit_depth == 8)
4462 {
4463 gray = gray & 0xff;
4464 sp = row + (size_t)row_width - 1;
4465 dp = row + ((size_t)row_width << 1) - 1;
4466
4467 for (i = 0; i < row_width; i++)
4468 {
4469 if ((*sp & 0xffU) == gray)
4470 *dp-- = 0;
4471
4472 else
4473 *dp-- = 0xff;
4474
4475 *dp-- = *sp--;
4476 }
4477 }
4478
4479 else if (row_info->bit_depth == 16)
4480 {
4481 unsigned int gray_high = (gray >> 8) & 0xff;
4482 unsigned int gray_low = gray & 0xff;
4483 sp = row + row_info->rowbytes - 1;
4484 dp = row + (row_info->rowbytes << 1) - 1;
4485 for (i = 0; i < row_width; i++)
4486 {
4487 if ((*(sp - 1) & 0xffU) == gray_high &&
4488 (*(sp) & 0xffU) == gray_low)
4489 {
4490 *dp-- = 0;
4491 *dp-- = 0;
4492 }
4493
4494 else
4495 {
4496 *dp-- = 0xff;
4497 *dp-- = 0xff;
4498 }
4499
4500 *dp-- = *sp--;
4501 *dp-- = *sp--;
4502 }
4503 }
4504
4505 row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
4506 row_info->channels = 2;
4507 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
4508 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
4509 row_width);
4510 }
4511 }
4512 else if (row_info->color_type == PNG_COLOR_TYPE_RGB &&
4513 trans_color != NULL)
4514 {
4515 if (row_info->bit_depth == 8)
4516 {
4517 png_byte red = (png_byte)(trans_color->red & 0xff);
4518 png_byte green = (png_byte)(trans_color->green & 0xff);
4519 png_byte blue = (png_byte)(trans_color->blue & 0xff);
4520 sp = row + (size_t)row_info->rowbytes - 1;
4521 dp = row + ((size_t)row_width << 2) - 1;
4522 for (i = 0; i < row_width; i++)
4523 {
4524 if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
4525 *dp-- = 0;
4526
4527 else
4528 *dp-- = 0xff;
4529
4530 *dp-- = *sp--;
4531 *dp-- = *sp--;
4532 *dp-- = *sp--;
4533 }
4534 }
4535 else if (row_info->bit_depth == 16)
4536 {
4537 png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff);
4538 png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff);
4539 png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff);
4540 png_byte red_low = (png_byte)(trans_color->red & 0xff);
4541 png_byte green_low = (png_byte)(trans_color->green & 0xff);
4542 png_byte blue_low = (png_byte)(trans_color->blue & 0xff);
4543 sp = row + row_info->rowbytes - 1;
4544 dp = row + ((size_t)row_width << 3) - 1;
4545 for (i = 0; i < row_width; i++)
4546 {
4547 if (*(sp - 5) == red_high &&
4548 *(sp - 4) == red_low &&
4549 *(sp - 3) == green_high &&
4550 *(sp - 2) == green_low &&
4551 *(sp - 1) == blue_high &&
4552 *(sp ) == blue_low)
4553 {
4554 *dp-- = 0;
4555 *dp-- = 0;
4556 }
4557
4558 else
4559 {
4560 *dp-- = 0xff;
4561 *dp-- = 0xff;
4562 }
4563
4564 *dp-- = *sp--;
4565 *dp-- = *sp--;
4566 *dp-- = *sp--;
4567 *dp-- = *sp--;
4568 *dp-- = *sp--;
4569 *dp-- = *sp--;
4570 }
4571 }
4572 row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
4573 row_info->channels = 4;
4574 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
4575 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4576 }
4577 }
4578 #endif
4579
4580 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4581 /* If the bit depth is 8 and the color type is not a palette type expand the
4582 * whole row to 16 bits. Has no effect otherwise.
4583 */
4584 static void
png_do_expand_16(png_row_infop row_info,png_bytep row)4585 png_do_expand_16(png_row_infop row_info, png_bytep row)
4586 {
4587 if (row_info->bit_depth == 8 &&
4588 row_info->color_type != PNG_COLOR_TYPE_PALETTE)
4589 {
4590 /* The row have a sequence of bytes containing [0..255] and we need
4591 * to turn it into another row containing [0..65535], to do this we
4592 * calculate:
4593 *
4594 * (input / 255) * 65535
4595 *
4596 * Which happens to be exactly input * 257 and this can be achieved
4597 * simply by byte replication in place (copying backwards).
4598 */
4599 png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */
4600 png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */
4601 while (dp > sp)
4602 {
4603 dp[-2] = dp[-1] = *--sp; dp -= 2;
4604 }
4605
4606 row_info->rowbytes *= 2;
4607 row_info->bit_depth = 16;
4608 row_info->pixel_depth = (png_byte)(row_info->channels * 16);
4609 }
4610 }
4611 #endif
4612
4613 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4614 static void
png_do_quantize(png_row_infop row_info,png_bytep row,png_const_bytep palette_lookup,png_const_bytep quantize_lookup)4615 png_do_quantize(png_row_infop row_info, png_bytep row,
4616 png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
4617 {
4618 png_bytep sp, dp;
4619 png_uint_32 i;
4620 png_uint_32 row_width=row_info->width;
4621
4622 png_debug(1, "in png_do_quantize");
4623
4624 if (row_info->bit_depth == 8)
4625 {
4626 if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup)
4627 {
4628 int r, g, b, p;
4629 sp = row;
4630 dp = row;
4631 for (i = 0; i < row_width; i++)
4632 {
4633 r = *sp++;
4634 g = *sp++;
4635 b = *sp++;
4636
4637 /* This looks real messy, but the compiler will reduce
4638 * it down to a reasonable formula. For example, with
4639 * 5 bits per color, we get:
4640 * p = (((r >> 3) & 0x1f) << 10) |
4641 * (((g >> 3) & 0x1f) << 5) |
4642 * ((b >> 3) & 0x1f);
4643 */
4644 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4645 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4646 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4647 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4648 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4649 (PNG_QUANTIZE_BLUE_BITS)) |
4650 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4651 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4652
4653 *dp++ = palette_lookup[p];
4654 }
4655
4656 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4657 row_info->channels = 1;
4658 row_info->pixel_depth = row_info->bit_depth;
4659 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4660 }
4661
4662 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
4663 palette_lookup != NULL)
4664 {
4665 int r, g, b, p;
4666 sp = row;
4667 dp = row;
4668 for (i = 0; i < row_width; i++)
4669 {
4670 r = *sp++;
4671 g = *sp++;
4672 b = *sp++;
4673 sp++;
4674
4675 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4676 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4677 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4678 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4679 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4680 (PNG_QUANTIZE_BLUE_BITS)) |
4681 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4682 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4683
4684 *dp++ = palette_lookup[p];
4685 }
4686
4687 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4688 row_info->channels = 1;
4689 row_info->pixel_depth = row_info->bit_depth;
4690 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4691 }
4692
4693 else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4694 quantize_lookup)
4695 {
4696 sp = row;
4697
4698 for (i = 0; i < row_width; i++, sp++)
4699 {
4700 *sp = quantize_lookup[*sp];
4701 }
4702 }
4703 }
4704 }
4705 #endif /* READ_QUANTIZE */
4706
4707 /* Transform the row. The order of transformations is significant,
4708 * and is very touchy. If you add a transformation, take care to
4709 * decide how it fits in with the other transformations here.
4710 */
4711 void /* PRIVATE */
png_do_read_transformations(png_structrp png_ptr,png_row_infop row_info)4712 png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
4713 {
4714 png_debug(1, "in png_do_read_transformations");
4715
4716 if (png_ptr->row_buf == NULL)
4717 {
4718 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
4719 * error is incredibly rare and incredibly easy to debug without this
4720 * information.
4721 */
4722 png_error(png_ptr, "NULL row buffer");
4723 }
4724
4725 /* The following is debugging; prior to 1.5.4 the code was never compiled in;
4726 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
4727 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for
4728 * all transformations, however in practice the ROW_INIT always gets done on
4729 * demand, if necessary.
4730 */
4731 if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
4732 (png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
4733 {
4734 /* Application has failed to call either png_read_start_image() or
4735 * png_read_update_info() after setting transforms that expand pixels.
4736 * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
4737 */
4738 png_error(png_ptr, "Uninitialized row");
4739 }
4740
4741 #ifdef PNG_READ_EXPAND_SUPPORTED
4742 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4743 {
4744 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4745 {
4746 png_do_expand_palette(row_info, png_ptr->row_buf + 1,
4747 png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
4748 }
4749
4750 else
4751 {
4752 if (png_ptr->num_trans != 0 &&
4753 (png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
4754 png_do_expand(row_info, png_ptr->row_buf + 1,
4755 &(png_ptr->trans_color));
4756
4757 else
4758 png_do_expand(row_info, png_ptr->row_buf + 1, NULL);
4759 }
4760 }
4761 #endif
4762
4763 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4764 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4765 (png_ptr->transformations & PNG_COMPOSE) == 0 &&
4766 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4767 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4768 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4769 0 /* at_start == false, because SWAP_ALPHA happens later */);
4770 #endif
4771
4772 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4773 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
4774 {
4775 int rgb_error =
4776 png_do_rgb_to_gray(png_ptr, row_info,
4777 png_ptr->row_buf + 1);
4778
4779 if (rgb_error != 0)
4780 {
4781 png_ptr->rgb_to_gray_status=1;
4782 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4783 PNG_RGB_TO_GRAY_WARN)
4784 png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4785
4786 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4787 PNG_RGB_TO_GRAY_ERR)
4788 png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4789 }
4790 }
4791 #endif
4792
4793 /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
4794 *
4795 * In most cases, the "simple transparency" should be done prior to doing
4796 * gray-to-RGB, or you will have to test 3x as many bytes to check if a
4797 * pixel is transparent. You would also need to make sure that the
4798 * transparency information is upgraded to RGB.
4799 *
4800 * To summarize, the current flow is:
4801 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
4802 * with background "in place" if transparent,
4803 * convert to RGB if necessary
4804 * - Gray + alpha -> composite with gray background and remove alpha bytes,
4805 * convert to RGB if necessary
4806 *
4807 * To support RGB backgrounds for gray images we need:
4808 * - Gray + simple transparency -> convert to RGB + simple transparency,
4809 * compare 3 or 6 bytes and composite with
4810 * background "in place" if transparent
4811 * (3x compare/pixel compared to doing
4812 * composite with gray bkgrnd)
4813 * - Gray + alpha -> convert to RGB + alpha, composite with background and
4814 * remove alpha bytes (3x float
4815 * operations/pixel compared with composite
4816 * on gray background)
4817 *
4818 * Greg's change will do this. The reason it wasn't done before is for
4819 * performance, as this increases the per-pixel operations. If we would check
4820 * in advance if the background was gray or RGB, and position the gray-to-RGB
4821 * transform appropriately, then it would save a lot of work/time.
4822 */
4823
4824 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4825 /* If gray -> RGB, do so now only if background is non-gray; else do later
4826 * for performance reasons
4827 */
4828 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4829 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) == 0)
4830 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4831 #endif
4832
4833 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4834 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4835 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
4836 png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
4837 #endif
4838
4839 #ifdef PNG_READ_GAMMA_SUPPORTED
4840 if ((png_ptr->transformations & PNG_GAMMA) != 0 &&
4841 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4842 /* Because RGB_TO_GRAY does the gamma transform. */
4843 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0 &&
4844 #endif
4845 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4846 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4847 /* Because PNG_COMPOSE does the gamma transform if there is something to
4848 * do (if there is an alpha channel or transparency.)
4849 */
4850 !((png_ptr->transformations & PNG_COMPOSE) != 0 &&
4851 ((png_ptr->num_trans != 0) ||
4852 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)) &&
4853 #endif
4854 /* Because png_init_read_transformations transforms the palette, unless
4855 * RGB_TO_GRAY will do the transform.
4856 */
4857 (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
4858 png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
4859 #endif
4860
4861 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4862 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4863 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
4864 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4865 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4866 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4867 0 /* at_start == false, because SWAP_ALPHA happens later */);
4868 #endif
4869
4870 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4871 if ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
4872 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4873 png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
4874 #endif
4875
4876 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
4877 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
4878 png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
4879 #endif
4880
4881 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
4882 /* There is no harm in doing both of these because only one has any effect,
4883 * by putting the 'scale' option first if the app asks for scale (either by
4884 * calling the API or in a TRANSFORM flag) this is what happens.
4885 */
4886 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
4887 png_do_chop(row_info, png_ptr->row_buf + 1);
4888 #endif
4889
4890 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4891 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
4892 {
4893 png_do_quantize(row_info, png_ptr->row_buf + 1,
4894 png_ptr->palette_lookup, png_ptr->quantize_index);
4895
4896 if (row_info->rowbytes == 0)
4897 png_error(png_ptr, "png_do_quantize returned rowbytes=0");
4898 }
4899 #endif /* READ_QUANTIZE */
4900
4901 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4902 /* Do the expansion now, after all the arithmetic has been done. Notice
4903 * that previous transformations can handle the PNG_EXPAND_16 flag if this
4904 * is efficient (particularly true in the case of gamma correction, where
4905 * better accuracy results faster!)
4906 */
4907 if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
4908 png_do_expand_16(row_info, png_ptr->row_buf + 1);
4909 #endif
4910
4911 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4912 /* NOTE: moved here in 1.5.4 (from much later in this list.) */
4913 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4914 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) != 0)
4915 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4916 #endif
4917
4918 #ifdef PNG_READ_INVERT_SUPPORTED
4919 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
4920 png_do_invert(row_info, png_ptr->row_buf + 1);
4921 #endif
4922
4923 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
4924 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
4925 png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
4926 #endif
4927
4928 #ifdef PNG_READ_SHIFT_SUPPORTED
4929 if ((png_ptr->transformations & PNG_SHIFT) != 0)
4930 png_do_unshift(row_info, png_ptr->row_buf + 1,
4931 &(png_ptr->shift));
4932 #endif
4933
4934 #ifdef PNG_READ_PACK_SUPPORTED
4935 if ((png_ptr->transformations & PNG_PACK) != 0)
4936 png_do_unpack(row_info, png_ptr->row_buf + 1);
4937 #endif
4938
4939 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
4940 /* Added at libpng-1.5.10 */
4941 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4942 png_ptr->num_palette_max >= 0)
4943 png_do_check_palette_indexes(png_ptr, row_info);
4944 #endif
4945
4946 #ifdef PNG_READ_BGR_SUPPORTED
4947 if ((png_ptr->transformations & PNG_BGR) != 0)
4948 png_do_bgr(row_info, png_ptr->row_buf + 1);
4949 #endif
4950
4951 #ifdef PNG_READ_PACKSWAP_SUPPORTED
4952 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
4953 png_do_packswap(row_info, png_ptr->row_buf + 1);
4954 #endif
4955
4956 #ifdef PNG_READ_FILLER_SUPPORTED
4957 if ((png_ptr->transformations & PNG_FILLER) != 0)
4958 png_do_read_filler(row_info, png_ptr->row_buf + 1,
4959 (png_uint_32)png_ptr->filler, png_ptr->flags);
4960 #endif
4961
4962 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
4963 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
4964 png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
4965 #endif
4966
4967 #ifdef PNG_READ_16BIT_SUPPORTED
4968 #ifdef PNG_READ_SWAP_SUPPORTED
4969 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
4970 png_do_swap(row_info, png_ptr->row_buf + 1);
4971 #endif
4972 #endif
4973
4974 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
4975 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
4976 {
4977 if (png_ptr->read_user_transform_fn != NULL)
4978 (*(png_ptr->read_user_transform_fn)) /* User read transform function */
4979 (png_ptr, /* png_ptr */
4980 row_info, /* row_info: */
4981 /* png_uint_32 width; width of row */
4982 /* size_t rowbytes; number of bytes in row */
4983 /* png_byte color_type; color type of pixels */
4984 /* png_byte bit_depth; bit depth of samples */
4985 /* png_byte channels; number of channels (1-4) */
4986 /* png_byte pixel_depth; bits per pixel (depth*channels) */
4987 png_ptr->row_buf + 1); /* start of pixel data for row */
4988 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
4989 if (png_ptr->user_transform_depth != 0)
4990 row_info->bit_depth = png_ptr->user_transform_depth;
4991
4992 if (png_ptr->user_transform_channels != 0)
4993 row_info->channels = png_ptr->user_transform_channels;
4994 #endif
4995 row_info->pixel_depth = (png_byte)(row_info->bit_depth *
4996 row_info->channels);
4997
4998 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
4999 }
5000 #endif
5001 }
5002
5003 #endif /* READ_TRANSFORMS */
5004 #endif /* READ */
5005