1
2 /* pngrtran.c - transforms the data in a row for PNG readers
3 *
4 * Last changed in libpng 1.6.10 [March 6, 2014]
5 * Copyright (c) 1998-2014 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 *
13 * This file contains functions optionally called by an application
14 * in order to tell libpng how to handle data when reading a PNG.
15 * Transformations that are used in both reading and writing are
16 * in pngtrans.c.
17 */
18
19 #include "pngpriv.h"
20
21 #ifdef PNG_READ_SUPPORTED
22
23 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
24 void PNGAPI
png_set_crc_action(png_structrp png_ptr,int crit_action,int ancil_action)25 png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
26 {
27 png_debug(1, "in png_set_crc_action");
28
29 if (png_ptr == NULL)
30 return;
31
32 /* Tell libpng how we react to CRC errors in critical chunks */
33 switch (crit_action)
34 {
35 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
36 break;
37
38 case PNG_CRC_WARN_USE: /* Warn/use data */
39 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
40 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
41 break;
42
43 case PNG_CRC_QUIET_USE: /* Quiet/use data */
44 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
45 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
46 PNG_FLAG_CRC_CRITICAL_IGNORE;
47 break;
48
49 case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */
50 png_warning(png_ptr,
51 "Can't discard critical data on CRC error");
52 case PNG_CRC_ERROR_QUIT: /* Error/quit */
53
54 case PNG_CRC_DEFAULT:
55 default:
56 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
57 break;
58 }
59
60 /* Tell libpng how we react to CRC errors in ancillary chunks */
61 switch (ancil_action)
62 {
63 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
64 break;
65
66 case PNG_CRC_WARN_USE: /* Warn/use data */
67 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
68 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
69 break;
70
71 case PNG_CRC_QUIET_USE: /* Quiet/use data */
72 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
73 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
74 PNG_FLAG_CRC_ANCILLARY_NOWARN;
75 break;
76
77 case PNG_CRC_ERROR_QUIT: /* Error/quit */
78 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
79 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
80 break;
81
82 case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
83
84 case PNG_CRC_DEFAULT:
85 default:
86 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
87 break;
88 }
89 }
90
91 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
92 /* Is it OK to set a transformation now? Only if png_start_read_image or
93 * png_read_update_info have not been called. It is not necessary for the IHDR
94 * to have been read in all cases, the parameter allows for this check too.
95 */
96 static int
png_rtran_ok(png_structrp png_ptr,int need_IHDR)97 png_rtran_ok(png_structrp png_ptr, int need_IHDR)
98 {
99 if (png_ptr != NULL)
100 {
101 if (png_ptr->flags & PNG_FLAG_ROW_INIT)
102 png_app_error(png_ptr,
103 "invalid after png_start_read_image or png_read_update_info");
104
105 else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
106 png_app_error(png_ptr, "invalid before the PNG header has been read");
107
108 else
109 {
110 /* Turn on failure to initialize correctly for all transforms. */
111 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
112
113 return 1; /* Ok */
114 }
115 }
116
117 return 0; /* no png_error possible! */
118 }
119 #endif
120
121 #ifdef PNG_READ_BACKGROUND_SUPPORTED
122 /* Handle alpha and tRNS via a background color */
123 void PNGFAPI
png_set_background_fixed(png_structrp png_ptr,png_const_color_16p background_color,int background_gamma_code,int need_expand,png_fixed_point background_gamma)124 png_set_background_fixed(png_structrp png_ptr,
125 png_const_color_16p background_color, int background_gamma_code,
126 int need_expand, png_fixed_point background_gamma)
127 {
128 png_debug(1, "in png_set_background_fixed");
129
130 if (!png_rtran_ok(png_ptr, 0) || background_color == NULL)
131 return;
132
133 if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
134 {
135 png_warning(png_ptr, "Application must supply a known background gamma");
136 return;
137 }
138
139 png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
140 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
141 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
142
143 png_ptr->background = *background_color;
144 png_ptr->background_gamma = background_gamma;
145 png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
146 if (need_expand)
147 png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
148 else
149 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
150 }
151
152 # ifdef PNG_FLOATING_POINT_SUPPORTED
153 void PNGAPI
png_set_background(png_structrp png_ptr,png_const_color_16p background_color,int background_gamma_code,int need_expand,double background_gamma)154 png_set_background(png_structrp png_ptr,
155 png_const_color_16p background_color, int background_gamma_code,
156 int need_expand, double background_gamma)
157 {
158 png_set_background_fixed(png_ptr, background_color, background_gamma_code,
159 need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
160 }
161 # endif /* FLOATING_POINT */
162 #endif /* READ_BACKGROUND */
163
164 /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
165 * one that pngrtran does first (scale) happens. This is necessary to allow the
166 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
167 */
168 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
169 void PNGAPI
png_set_scale_16(png_structrp png_ptr)170 png_set_scale_16(png_structrp png_ptr)
171 {
172 png_debug(1, "in png_set_scale_16");
173
174 if (!png_rtran_ok(png_ptr, 0))
175 return;
176
177 png_ptr->transformations |= PNG_SCALE_16_TO_8;
178 }
179 #endif
180
181 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
182 /* Chop 16-bit depth files to 8-bit depth */
183 void PNGAPI
png_set_strip_16(png_structrp png_ptr)184 png_set_strip_16(png_structrp png_ptr)
185 {
186 png_debug(1, "in png_set_strip_16");
187
188 if (!png_rtran_ok(png_ptr, 0))
189 return;
190
191 png_ptr->transformations |= PNG_16_TO_8;
192 }
193 #endif
194
195 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
196 void PNGAPI
png_set_strip_alpha(png_structrp png_ptr)197 png_set_strip_alpha(png_structrp png_ptr)
198 {
199 png_debug(1, "in png_set_strip_alpha");
200
201 if (!png_rtran_ok(png_ptr, 0))
202 return;
203
204 png_ptr->transformations |= PNG_STRIP_ALPHA;
205 }
206 #endif
207
208 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
209 static png_fixed_point
translate_gamma_flags(png_structrp png_ptr,png_fixed_point output_gamma,int is_screen)210 translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
211 int is_screen)
212 {
213 /* Check for flag values. The main reason for having the old Mac value as a
214 * flag is that it is pretty near impossible to work out what the correct
215 * value is from Apple documentation - a working Mac system is needed to
216 * discover the value!
217 */
218 if (output_gamma == PNG_DEFAULT_sRGB ||
219 output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
220 {
221 /* If there is no sRGB support this just sets the gamma to the standard
222 * sRGB value. (This is a side effect of using this function!)
223 */
224 # ifdef PNG_READ_sRGB_SUPPORTED
225 png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
226 # else
227 PNG_UNUSED(png_ptr)
228 # endif
229 if (is_screen)
230 output_gamma = PNG_GAMMA_sRGB;
231 else
232 output_gamma = PNG_GAMMA_sRGB_INVERSE;
233 }
234
235 else if (output_gamma == PNG_GAMMA_MAC_18 ||
236 output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
237 {
238 if (is_screen)
239 output_gamma = PNG_GAMMA_MAC_OLD;
240 else
241 output_gamma = PNG_GAMMA_MAC_INVERSE;
242 }
243
244 return output_gamma;
245 }
246
247 # ifdef PNG_FLOATING_POINT_SUPPORTED
248 static png_fixed_point
convert_gamma_value(png_structrp png_ptr,double output_gamma)249 convert_gamma_value(png_structrp png_ptr, double output_gamma)
250 {
251 /* The following silently ignores cases where fixed point (times 100,000)
252 * gamma values are passed to the floating point API. This is safe and it
253 * means the fixed point constants work just fine with the floating point
254 * API. The alternative would just lead to undetected errors and spurious
255 * bug reports. Negative values fail inside the _fixed API unless they
256 * correspond to the flag values.
257 */
258 if (output_gamma > 0 && output_gamma < 128)
259 output_gamma *= PNG_FP_1;
260
261 /* This preserves -1 and -2 exactly: */
262 output_gamma = floor(output_gamma + .5);
263
264 if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
265 png_fixed_error(png_ptr, "gamma value");
266
267 return (png_fixed_point)output_gamma;
268 }
269 # endif
270 #endif /* READ_ALPHA_MODE || READ_GAMMA */
271
272 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
273 void PNGFAPI
png_set_alpha_mode_fixed(png_structrp png_ptr,int mode,png_fixed_point output_gamma)274 png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
275 png_fixed_point output_gamma)
276 {
277 int compose = 0;
278 png_fixed_point file_gamma;
279
280 png_debug(1, "in png_set_alpha_mode");
281
282 if (!png_rtran_ok(png_ptr, 0))
283 return;
284
285 output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
286
287 /* Validate the value to ensure it is in a reasonable range. The value
288 * is expected to be 1 or greater, but this range test allows for some
289 * viewing correction values. The intent is to weed out users of this API
290 * who use the inverse of the gamma value accidentally! Since some of these
291 * values are reasonable this may have to be changed.
292 */
293 if (output_gamma < 70000 || output_gamma > 300000)
294 png_error(png_ptr, "output gamma out of expected range");
295
296 /* The default file gamma is the inverse of the output gamma; the output
297 * gamma may be changed below so get the file value first:
298 */
299 file_gamma = png_reciprocal(output_gamma);
300
301 /* There are really 8 possibilities here, composed of any combination
302 * of:
303 *
304 * premultiply the color channels
305 * do not encode non-opaque pixels
306 * encode the alpha as well as the color channels
307 *
308 * The differences disappear if the input/output ('screen') gamma is 1.0,
309 * because then the encoding is a no-op and there is only the choice of
310 * premultiplying the color channels or not.
311 *
312 * png_set_alpha_mode and png_set_background interact because both use
313 * png_compose to do the work. Calling both is only useful when
314 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
315 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
316 */
317 switch (mode)
318 {
319 case PNG_ALPHA_PNG: /* default: png standard */
320 /* No compose, but it may be set by png_set_background! */
321 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
322 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
323 break;
324
325 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
326 compose = 1;
327 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
328 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
329 /* The output is linear: */
330 output_gamma = PNG_FP_1;
331 break;
332
333 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
334 compose = 1;
335 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
336 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
337 /* output_gamma records the encoding of opaque pixels! */
338 break;
339
340 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
341 compose = 1;
342 png_ptr->transformations |= PNG_ENCODE_ALPHA;
343 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
344 break;
345
346 default:
347 png_error(png_ptr, "invalid alpha mode");
348 }
349
350 /* Only set the default gamma if the file gamma has not been set (this has
351 * the side effect that the gamma in a second call to png_set_alpha_mode will
352 * be ignored.)
353 */
354 if (png_ptr->colorspace.gamma == 0)
355 {
356 png_ptr->colorspace.gamma = file_gamma;
357 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
358 }
359
360 /* But always set the output gamma: */
361 png_ptr->screen_gamma = output_gamma;
362
363 /* Finally, if pre-multiplying, set the background fields to achieve the
364 * desired result.
365 */
366 if (compose)
367 {
368 /* And obtain alpha pre-multiplication by composing on black: */
369 memset(&png_ptr->background, 0, (sizeof png_ptr->background));
370 png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
371 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
372 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
373
374 if (png_ptr->transformations & PNG_COMPOSE)
375 png_error(png_ptr,
376 "conflicting calls to set alpha mode and background");
377
378 png_ptr->transformations |= PNG_COMPOSE;
379 }
380 }
381
382 # ifdef PNG_FLOATING_POINT_SUPPORTED
383 void PNGAPI
png_set_alpha_mode(png_structrp png_ptr,int mode,double output_gamma)384 png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
385 {
386 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
387 output_gamma));
388 }
389 # endif
390 #endif
391
392 #ifdef PNG_READ_QUANTIZE_SUPPORTED
393 /* Dither file to 8-bit. Supply a palette, the current number
394 * of elements in the palette, the maximum number of elements
395 * allowed, and a histogram if possible. If the current number
396 * of colors is greater then the maximum number, the palette will be
397 * modified to fit in the maximum number. "full_quantize" indicates
398 * whether we need a quantizing cube set up for RGB images, or if we
399 * simply are reducing the number of colors in a paletted image.
400 */
401
402 typedef struct png_dsort_struct
403 {
404 struct png_dsort_struct * next;
405 png_byte left;
406 png_byte right;
407 } png_dsort;
408 typedef png_dsort * png_dsortp;
409 typedef png_dsort * * png_dsortpp;
410
411 void PNGAPI
png_set_quantize(png_structrp png_ptr,png_colorp palette,int num_palette,int maximum_colors,png_const_uint_16p histogram,int full_quantize)412 png_set_quantize(png_structrp png_ptr, png_colorp palette,
413 int num_palette, int maximum_colors, png_const_uint_16p histogram,
414 int full_quantize)
415 {
416 png_debug(1, "in png_set_quantize");
417
418 if (!png_rtran_ok(png_ptr, 0))
419 return;
420
421 png_ptr->transformations |= PNG_QUANTIZE;
422
423 if (!full_quantize)
424 {
425 int i;
426
427 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
428 (png_uint_32)(num_palette * (sizeof (png_byte))));
429 for (i = 0; i < num_palette; i++)
430 png_ptr->quantize_index[i] = (png_byte)i;
431 }
432
433 if (num_palette > maximum_colors)
434 {
435 if (histogram != NULL)
436 {
437 /* This is easy enough, just throw out the least used colors.
438 * Perhaps not the best solution, but good enough.
439 */
440
441 int i;
442
443 /* Initialize an array to sort colors */
444 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
445 (png_uint_32)(num_palette * (sizeof (png_byte))));
446
447 /* Initialize the quantize_sort array */
448 for (i = 0; i < num_palette; i++)
449 png_ptr->quantize_sort[i] = (png_byte)i;
450
451 /* Find the least used palette entries by starting a
452 * bubble sort, and running it until we have sorted
453 * out enough colors. Note that we don't care about
454 * sorting all the colors, just finding which are
455 * least used.
456 */
457
458 for (i = num_palette - 1; i >= maximum_colors; i--)
459 {
460 int done; /* To stop early if the list is pre-sorted */
461 int j;
462
463 done = 1;
464 for (j = 0; j < i; j++)
465 {
466 if (histogram[png_ptr->quantize_sort[j]]
467 < histogram[png_ptr->quantize_sort[j + 1]])
468 {
469 png_byte t;
470
471 t = png_ptr->quantize_sort[j];
472 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
473 png_ptr->quantize_sort[j + 1] = t;
474 done = 0;
475 }
476 }
477
478 if (done)
479 break;
480 }
481
482 /* Swap the palette around, and set up a table, if necessary */
483 if (full_quantize)
484 {
485 int j = num_palette;
486
487 /* Put all the useful colors within the max, but don't
488 * move the others.
489 */
490 for (i = 0; i < maximum_colors; i++)
491 {
492 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
493 {
494 do
495 j--;
496 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
497
498 palette[i] = palette[j];
499 }
500 }
501 }
502 else
503 {
504 int j = num_palette;
505
506 /* Move all the used colors inside the max limit, and
507 * develop a translation table.
508 */
509 for (i = 0; i < maximum_colors; i++)
510 {
511 /* Only move the colors we need to */
512 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
513 {
514 png_color tmp_color;
515
516 do
517 j--;
518 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
519
520 tmp_color = palette[j];
521 palette[j] = palette[i];
522 palette[i] = tmp_color;
523 /* Indicate where the color went */
524 png_ptr->quantize_index[j] = (png_byte)i;
525 png_ptr->quantize_index[i] = (png_byte)j;
526 }
527 }
528
529 /* Find closest color for those colors we are not using */
530 for (i = 0; i < num_palette; i++)
531 {
532 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
533 {
534 int min_d, k, min_k, d_index;
535
536 /* Find the closest color to one we threw out */
537 d_index = png_ptr->quantize_index[i];
538 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
539 for (k = 1, min_k = 0; k < maximum_colors; k++)
540 {
541 int d;
542
543 d = PNG_COLOR_DIST(palette[d_index], palette[k]);
544
545 if (d < min_d)
546 {
547 min_d = d;
548 min_k = k;
549 }
550 }
551 /* Point to closest color */
552 png_ptr->quantize_index[i] = (png_byte)min_k;
553 }
554 }
555 }
556 png_free(png_ptr, png_ptr->quantize_sort);
557 png_ptr->quantize_sort = NULL;
558 }
559 else
560 {
561 /* This is much harder to do simply (and quickly). Perhaps
562 * we need to go through a median cut routine, but those
563 * don't always behave themselves with only a few colors
564 * as input. So we will just find the closest two colors,
565 * and throw out one of them (chosen somewhat randomly).
566 * [We don't understand this at all, so if someone wants to
567 * work on improving it, be our guest - AED, GRP]
568 */
569 int i;
570 int max_d;
571 int num_new_palette;
572 png_dsortp t;
573 png_dsortpp hash;
574
575 t = NULL;
576
577 /* Initialize palette index arrays */
578 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
579 (png_uint_32)(num_palette * (sizeof (png_byte))));
580 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
581 (png_uint_32)(num_palette * (sizeof (png_byte))));
582
583 /* Initialize the sort array */
584 for (i = 0; i < num_palette; i++)
585 {
586 png_ptr->index_to_palette[i] = (png_byte)i;
587 png_ptr->palette_to_index[i] = (png_byte)i;
588 }
589
590 hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
591 (sizeof (png_dsortp))));
592
593 num_new_palette = num_palette;
594
595 /* Initial wild guess at how far apart the farthest pixel
596 * pair we will be eliminating will be. Larger
597 * numbers mean more areas will be allocated, Smaller
598 * numbers run the risk of not saving enough data, and
599 * having to do this all over again.
600 *
601 * I have not done extensive checking on this number.
602 */
603 max_d = 96;
604
605 while (num_new_palette > maximum_colors)
606 {
607 for (i = 0; i < num_new_palette - 1; i++)
608 {
609 int j;
610
611 for (j = i + 1; j < num_new_palette; j++)
612 {
613 int d;
614
615 d = PNG_COLOR_DIST(palette[i], palette[j]);
616
617 if (d <= max_d)
618 {
619
620 t = (png_dsortp)png_malloc_warn(png_ptr,
621 (png_uint_32)(sizeof (png_dsort)));
622
623 if (t == NULL)
624 break;
625
626 t->next = hash[d];
627 t->left = (png_byte)i;
628 t->right = (png_byte)j;
629 hash[d] = t;
630 }
631 }
632 if (t == NULL)
633 break;
634 }
635
636 if (t != NULL)
637 for (i = 0; i <= max_d; i++)
638 {
639 if (hash[i] != NULL)
640 {
641 png_dsortp p;
642
643 for (p = hash[i]; p; p = p->next)
644 {
645 if ((int)png_ptr->index_to_palette[p->left]
646 < num_new_palette &&
647 (int)png_ptr->index_to_palette[p->right]
648 < num_new_palette)
649 {
650 int j, next_j;
651
652 if (num_new_palette & 0x01)
653 {
654 j = p->left;
655 next_j = p->right;
656 }
657 else
658 {
659 j = p->right;
660 next_j = p->left;
661 }
662
663 num_new_palette--;
664 palette[png_ptr->index_to_palette[j]]
665 = palette[num_new_palette];
666 if (!full_quantize)
667 {
668 int k;
669
670 for (k = 0; k < num_palette; k++)
671 {
672 if (png_ptr->quantize_index[k] ==
673 png_ptr->index_to_palette[j])
674 png_ptr->quantize_index[k] =
675 png_ptr->index_to_palette[next_j];
676
677 if ((int)png_ptr->quantize_index[k] ==
678 num_new_palette)
679 png_ptr->quantize_index[k] =
680 png_ptr->index_to_palette[j];
681 }
682 }
683
684 png_ptr->index_to_palette[png_ptr->palette_to_index
685 [num_new_palette]] = png_ptr->index_to_palette[j];
686
687 png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
688 = png_ptr->palette_to_index[num_new_palette];
689
690 png_ptr->index_to_palette[j] =
691 (png_byte)num_new_palette;
692
693 png_ptr->palette_to_index[num_new_palette] =
694 (png_byte)j;
695 }
696 if (num_new_palette <= maximum_colors)
697 break;
698 }
699 if (num_new_palette <= maximum_colors)
700 break;
701 }
702 }
703
704 for (i = 0; i < 769; i++)
705 {
706 if (hash[i] != NULL)
707 {
708 png_dsortp p = hash[i];
709 while (p)
710 {
711 t = p->next;
712 png_free(png_ptr, p);
713 p = t;
714 }
715 }
716 hash[i] = 0;
717 }
718 max_d += 96;
719 }
720 png_free(png_ptr, hash);
721 png_free(png_ptr, png_ptr->palette_to_index);
722 png_free(png_ptr, png_ptr->index_to_palette);
723 png_ptr->palette_to_index = NULL;
724 png_ptr->index_to_palette = NULL;
725 }
726 num_palette = maximum_colors;
727 }
728 if (png_ptr->palette == NULL)
729 {
730 png_ptr->palette = palette;
731 }
732 png_ptr->num_palette = (png_uint_16)num_palette;
733
734 if (full_quantize)
735 {
736 int i;
737 png_bytep distance;
738 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
739 PNG_QUANTIZE_BLUE_BITS;
740 int num_red = (1 << PNG_QUANTIZE_RED_BITS);
741 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
742 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
743 png_size_t num_entries = ((png_size_t)1 << total_bits);
744
745 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
746 (png_uint_32)(num_entries * (sizeof (png_byte))));
747
748 distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
749 (sizeof (png_byte))));
750
751 memset(distance, 0xff, num_entries * (sizeof (png_byte)));
752
753 for (i = 0; i < num_palette; i++)
754 {
755 int ir, ig, ib;
756 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
757 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
758 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
759
760 for (ir = 0; ir < num_red; ir++)
761 {
762 /* int dr = abs(ir - r); */
763 int dr = ((ir > r) ? ir - r : r - ir);
764 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
765 PNG_QUANTIZE_GREEN_BITS));
766
767 for (ig = 0; ig < num_green; ig++)
768 {
769 /* int dg = abs(ig - g); */
770 int dg = ((ig > g) ? ig - g : g - ig);
771 int dt = dr + dg;
772 int dm = ((dr > dg) ? dr : dg);
773 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
774
775 for (ib = 0; ib < num_blue; ib++)
776 {
777 int d_index = index_g | ib;
778 /* int db = abs(ib - b); */
779 int db = ((ib > b) ? ib - b : b - ib);
780 int dmax = ((dm > db) ? dm : db);
781 int d = dmax + dt + db;
782
783 if (d < (int)distance[d_index])
784 {
785 distance[d_index] = (png_byte)d;
786 png_ptr->palette_lookup[d_index] = (png_byte)i;
787 }
788 }
789 }
790 }
791 }
792
793 png_free(png_ptr, distance);
794 }
795 }
796 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
797
798 #ifdef PNG_READ_GAMMA_SUPPORTED
799 void PNGFAPI
png_set_gamma_fixed(png_structrp png_ptr,png_fixed_point scrn_gamma,png_fixed_point file_gamma)800 png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
801 png_fixed_point file_gamma)
802 {
803 png_debug(1, "in png_set_gamma_fixed");
804
805 if (!png_rtran_ok(png_ptr, 0))
806 return;
807
808 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
809 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
810 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
811
812 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
813 * premultiplied alpha support; this actually hides an undocumented feature
814 * of the previous implementation which allowed gamma processing to be
815 * disabled in background handling. There is no evidence (so far) that this
816 * was being used; however, png_set_background itself accepted and must still
817 * accept '0' for the gamma value it takes, because it isn't always used.
818 *
819 * Since this is an API change (albeit a very minor one that removes an
820 * undocumented API feature) the following checks were only enabled in
821 * libpng-1.6.0.
822 */
823 if (file_gamma <= 0)
824 png_error(png_ptr, "invalid file gamma in png_set_gamma");
825
826 if (scrn_gamma <= 0)
827 png_error(png_ptr, "invalid screen gamma in png_set_gamma");
828
829 /* Set the gamma values unconditionally - this overrides the value in the PNG
830 * file if a gAMA chunk was present. png_set_alpha_mode provides a
831 * different, easier, way to default the file gamma.
832 */
833 png_ptr->colorspace.gamma = file_gamma;
834 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
835 png_ptr->screen_gamma = scrn_gamma;
836 }
837
838 # ifdef PNG_FLOATING_POINT_SUPPORTED
839 void PNGAPI
png_set_gamma(png_structrp png_ptr,double scrn_gamma,double file_gamma)840 png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
841 {
842 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
843 convert_gamma_value(png_ptr, file_gamma));
844 }
845 # endif /* FLOATING_POINT_SUPPORTED */
846 #endif /* READ_GAMMA */
847
848 #ifdef PNG_READ_EXPAND_SUPPORTED
849 /* Expand paletted images to RGB, expand grayscale images of
850 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
851 * to alpha channels.
852 */
853 void PNGAPI
png_set_expand(png_structrp png_ptr)854 png_set_expand(png_structrp png_ptr)
855 {
856 png_debug(1, "in png_set_expand");
857
858 if (!png_rtran_ok(png_ptr, 0))
859 return;
860
861 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
862 }
863
864 /* GRR 19990627: the following three functions currently are identical
865 * to png_set_expand(). However, it is entirely reasonable that someone
866 * might wish to expand an indexed image to RGB but *not* expand a single,
867 * fully transparent palette entry to a full alpha channel--perhaps instead
868 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
869 * the transparent color with a particular RGB value, or drop tRNS entirely.
870 * IOW, a future version of the library may make the transformations flag
871 * a bit more fine-grained, with separate bits for each of these three
872 * functions.
873 *
874 * More to the point, these functions make it obvious what libpng will be
875 * doing, whereas "expand" can (and does) mean any number of things.
876 *
877 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
878 * to expand only the sample depth but not to expand the tRNS to alpha
879 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
880 */
881
882 /* Expand paletted images to RGB. */
883 void PNGAPI
png_set_palette_to_rgb(png_structrp png_ptr)884 png_set_palette_to_rgb(png_structrp png_ptr)
885 {
886 png_debug(1, "in png_set_palette_to_rgb");
887
888 if (!png_rtran_ok(png_ptr, 0))
889 return;
890
891 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
892 }
893
894 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
895 void PNGAPI
png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)896 png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
897 {
898 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
899
900 if (!png_rtran_ok(png_ptr, 0))
901 return;
902
903 png_ptr->transformations |= PNG_EXPAND;
904 }
905
906 /* Expand tRNS chunks to alpha channels. */
907 void PNGAPI
png_set_tRNS_to_alpha(png_structrp png_ptr)908 png_set_tRNS_to_alpha(png_structrp png_ptr)
909 {
910 png_debug(1, "in png_set_tRNS_to_alpha");
911
912 if (!png_rtran_ok(png_ptr, 0))
913 return;
914
915 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
916 }
917 #endif /* defined(PNG_READ_EXPAND_SUPPORTED) */
918
919 #ifdef PNG_READ_EXPAND_16_SUPPORTED
920 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
921 * it may not work correctly.)
922 */
923 void PNGAPI
png_set_expand_16(png_structrp png_ptr)924 png_set_expand_16(png_structrp png_ptr)
925 {
926 png_debug(1, "in png_set_expand_16");
927
928 if (!png_rtran_ok(png_ptr, 0))
929 return;
930
931 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
932 }
933 #endif
934
935 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
936 void PNGAPI
png_set_gray_to_rgb(png_structrp png_ptr)937 png_set_gray_to_rgb(png_structrp png_ptr)
938 {
939 png_debug(1, "in png_set_gray_to_rgb");
940
941 if (!png_rtran_ok(png_ptr, 0))
942 return;
943
944 /* Because rgb must be 8 bits or more: */
945 png_set_expand_gray_1_2_4_to_8(png_ptr);
946 png_ptr->transformations |= PNG_GRAY_TO_RGB;
947 }
948 #endif
949
950 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
951 void PNGFAPI
png_set_rgb_to_gray_fixed(png_structrp png_ptr,int error_action,png_fixed_point red,png_fixed_point green)952 png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
953 png_fixed_point red, png_fixed_point green)
954 {
955 png_debug(1, "in png_set_rgb_to_gray");
956
957 /* Need the IHDR here because of the check on color_type below. */
958 /* TODO: fix this */
959 if (!png_rtran_ok(png_ptr, 1))
960 return;
961
962 switch(error_action)
963 {
964 case PNG_ERROR_ACTION_NONE:
965 png_ptr->transformations |= PNG_RGB_TO_GRAY;
966 break;
967
968 case PNG_ERROR_ACTION_WARN:
969 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
970 break;
971
972 case PNG_ERROR_ACTION_ERROR:
973 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
974 break;
975
976 default:
977 png_error(png_ptr, "invalid error action to rgb_to_gray");
978 break;
979 }
980
981 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
982 #ifdef PNG_READ_EXPAND_SUPPORTED
983 png_ptr->transformations |= PNG_EXPAND;
984 #else
985 {
986 /* Make this an error in 1.6 because otherwise the application may assume
987 * that it just worked and get a memory overwrite.
988 */
989 png_error(png_ptr,
990 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
991
992 /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
993 }
994 #endif
995 {
996 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
997 {
998 png_uint_16 red_int, green_int;
999
1000 /* NOTE: this calculation does not round, but this behavior is retained
1001 * for consistency, the inaccuracy is very small. The code here always
1002 * overwrites the coefficients, regardless of whether they have been
1003 * defaulted or set already.
1004 */
1005 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
1006 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
1007
1008 png_ptr->rgb_to_gray_red_coeff = red_int;
1009 png_ptr->rgb_to_gray_green_coeff = green_int;
1010 png_ptr->rgb_to_gray_coefficients_set = 1;
1011 }
1012
1013 else
1014 {
1015 if (red >= 0 && green >= 0)
1016 png_app_warning(png_ptr,
1017 "ignoring out of range rgb_to_gray coefficients");
1018
1019 /* Use the defaults, from the cHRM chunk if set, else the historical
1020 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
1021 * png_do_rgb_to_gray for more discussion of the values. In this case
1022 * the coefficients are not marked as 'set' and are not overwritten if
1023 * something has already provided a default.
1024 */
1025 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
1026 png_ptr->rgb_to_gray_green_coeff == 0)
1027 {
1028 png_ptr->rgb_to_gray_red_coeff = 6968;
1029 png_ptr->rgb_to_gray_green_coeff = 23434;
1030 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1031 }
1032 }
1033 }
1034 }
1035
1036 #ifdef PNG_FLOATING_POINT_SUPPORTED
1037 /* Convert a RGB image to a grayscale of the same width. This allows us,
1038 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1039 */
1040
1041 void PNGAPI
png_set_rgb_to_gray(png_structrp png_ptr,int error_action,double red,double green)1042 png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
1043 double green)
1044 {
1045 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1046 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
1047 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
1048 }
1049 #endif /* FLOATING POINT */
1050
1051 #endif /* RGB_TO_GRAY */
1052
1053 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1054 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1055 void PNGAPI
png_set_read_user_transform_fn(png_structrp png_ptr,png_user_transform_ptr read_user_transform_fn)1056 png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1057 read_user_transform_fn)
1058 {
1059 png_debug(1, "in png_set_read_user_transform_fn");
1060
1061 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1062 png_ptr->transformations |= PNG_USER_TRANSFORM;
1063 png_ptr->read_user_transform_fn = read_user_transform_fn;
1064 #endif
1065 }
1066 #endif
1067
1068 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1069 #ifdef PNG_READ_GAMMA_SUPPORTED
1070 /* In the case of gamma transformations only do transformations on images where
1071 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1072 * slows things down slightly, and also needlessly introduces small errors.
1073 */
1074 static int /* PRIVATE */
png_gamma_threshold(png_fixed_point screen_gamma,png_fixed_point file_gamma)1075 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
1076 {
1077 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1078 * correction as a difference of the overall transform from 1.0
1079 *
1080 * We want to compare the threshold with s*f - 1, if we get
1081 * overflow here it is because of wacky gamma values so we
1082 * turn on processing anyway.
1083 */
1084 png_fixed_point gtest;
1085 return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) ||
1086 png_gamma_significant(gtest);
1087 }
1088 #endif
1089
1090 /* Initialize everything needed for the read. This includes modifying
1091 * the palette.
1092 */
1093
1094 /*For the moment 'png_init_palette_transformations' and
1095 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1096 * The intent is that these two routines should have palette or rgb operations
1097 * extracted from 'png_init_read_transformations'.
1098 */
1099 static void /* PRIVATE */
png_init_palette_transformations(png_structrp png_ptr)1100 png_init_palette_transformations(png_structrp png_ptr)
1101 {
1102 /* Called to handle the (input) palette case. In png_do_read_transformations
1103 * the first step is to expand the palette if requested, so this code must
1104 * take care to only make changes that are invariant with respect to the
1105 * palette expansion, or only do them if there is no expansion.
1106 *
1107 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1108 * to 0.)
1109 */
1110 int input_has_alpha = 0;
1111 int input_has_transparency = 0;
1112
1113 if (png_ptr->num_trans > 0)
1114 {
1115 int i;
1116
1117 /* Ignore if all the entries are opaque (unlikely!) */
1118 for (i=0; i<png_ptr->num_trans; ++i)
1119 {
1120 if (png_ptr->trans_alpha[i] == 255)
1121 continue;
1122 else if (png_ptr->trans_alpha[i] == 0)
1123 input_has_transparency = 1;
1124 else
1125 {
1126 input_has_transparency = 1;
1127 input_has_alpha = 1;
1128 break;
1129 }
1130 }
1131 }
1132
1133 /* If no alpha we can optimize. */
1134 if (!input_has_alpha)
1135 {
1136 /* Any alpha means background and associative alpha processing is
1137 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1138 * and ENCODE_ALPHA are irrelevant.
1139 */
1140 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1141 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1142
1143 if (!input_has_transparency)
1144 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1145 }
1146
1147 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1148 /* png_set_background handling - deals with the complexity of whether the
1149 * background color is in the file format or the screen format in the case
1150 * where an 'expand' will happen.
1151 */
1152
1153 /* The following code cannot be entered in the alpha pre-multiplication case
1154 * because PNG_BACKGROUND_EXPAND is cancelled below.
1155 */
1156 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1157 (png_ptr->transformations & PNG_EXPAND))
1158 {
1159 {
1160 png_ptr->background.red =
1161 png_ptr->palette[png_ptr->background.index].red;
1162 png_ptr->background.green =
1163 png_ptr->palette[png_ptr->background.index].green;
1164 png_ptr->background.blue =
1165 png_ptr->palette[png_ptr->background.index].blue;
1166
1167 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1168 if (png_ptr->transformations & PNG_INVERT_ALPHA)
1169 {
1170 if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
1171 {
1172 /* Invert the alpha channel (in tRNS) unless the pixels are
1173 * going to be expanded, in which case leave it for later
1174 */
1175 int i, istop = png_ptr->num_trans;
1176
1177 for (i=0; i<istop; i++)
1178 png_ptr->trans_alpha[i] = (png_byte)(255 -
1179 png_ptr->trans_alpha[i]);
1180 }
1181 }
1182 #endif /* PNG_READ_INVERT_ALPHA_SUPPORTED */
1183 }
1184 } /* background expand and (therefore) no alpha association. */
1185 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
1186 }
1187
1188 static void /* PRIVATE */
png_init_rgb_transformations(png_structrp png_ptr)1189 png_init_rgb_transformations(png_structrp png_ptr)
1190 {
1191 /* Added to libpng-1.5.4: check the color type to determine whether there
1192 * is any alpha or transparency in the image and simply cancel the
1193 * background and alpha mode stuff if there isn't.
1194 */
1195 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
1196 int input_has_transparency = png_ptr->num_trans > 0;
1197
1198 /* If no alpha we can optimize. */
1199 if (!input_has_alpha)
1200 {
1201 /* Any alpha means background and associative alpha processing is
1202 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1203 * and ENCODE_ALPHA are irrelevant.
1204 */
1205 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1206 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1207 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1208 # endif
1209
1210 if (!input_has_transparency)
1211 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1212 }
1213
1214 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1215 /* png_set_background handling - deals with the complexity of whether the
1216 * background color is in the file format or the screen format in the case
1217 * where an 'expand' will happen.
1218 */
1219
1220 /* The following code cannot be entered in the alpha pre-multiplication case
1221 * because PNG_BACKGROUND_EXPAND is cancelled below.
1222 */
1223 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1224 (png_ptr->transformations & PNG_EXPAND) &&
1225 !(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
1226 /* i.e., GRAY or GRAY_ALPHA */
1227 {
1228 {
1229 /* Expand background and tRNS chunks */
1230 int gray = png_ptr->background.gray;
1231 int trans_gray = png_ptr->trans_color.gray;
1232
1233 switch (png_ptr->bit_depth)
1234 {
1235 case 1:
1236 gray *= 0xff;
1237 trans_gray *= 0xff;
1238 break;
1239
1240 case 2:
1241 gray *= 0x55;
1242 trans_gray *= 0x55;
1243 break;
1244
1245 case 4:
1246 gray *= 0x11;
1247 trans_gray *= 0x11;
1248 break;
1249
1250 default:
1251
1252 case 8:
1253 /* FALL THROUGH (Already 8 bits) */
1254
1255 case 16:
1256 /* Already a full 16 bits */
1257 break;
1258 }
1259
1260 png_ptr->background.red = png_ptr->background.green =
1261 png_ptr->background.blue = (png_uint_16)gray;
1262
1263 if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
1264 {
1265 png_ptr->trans_color.red = png_ptr->trans_color.green =
1266 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
1267 }
1268 }
1269 } /* background expand and (therefore) no alpha association. */
1270 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
1271 }
1272
1273 void /* PRIVATE */
png_init_read_transformations(png_structrp png_ptr)1274 png_init_read_transformations(png_structrp png_ptr)
1275 {
1276 png_debug(1, "in png_init_read_transformations");
1277
1278 /* This internal function is called from png_read_start_row in pngrutil.c
1279 * and it is called before the 'rowbytes' calculation is done, so the code
1280 * in here can change or update the transformations flags.
1281 *
1282 * First do updates that do not depend on the details of the PNG image data
1283 * being processed.
1284 */
1285
1286 #ifdef PNG_READ_GAMMA_SUPPORTED
1287 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1288 * png_set_alpha_mode and this is another source for a default file gamma so
1289 * the test needs to be performed later - here. In addition prior to 1.5.4
1290 * the tests were repeated for the PALETTE color type here - this is no
1291 * longer necessary (and doesn't seem to have been necessary before.)
1292 */
1293 {
1294 /* The following temporary indicates if overall gamma correction is
1295 * required.
1296 */
1297 int gamma_correction = 0;
1298
1299 if (png_ptr->colorspace.gamma != 0) /* has been set */
1300 {
1301 if (png_ptr->screen_gamma != 0) /* screen set too */
1302 gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
1303 png_ptr->screen_gamma);
1304
1305 else
1306 /* Assume the output matches the input; a long time default behavior
1307 * of libpng, although the standard has nothing to say about this.
1308 */
1309 png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
1310 }
1311
1312 else if (png_ptr->screen_gamma != 0)
1313 /* The converse - assume the file matches the screen, note that this
1314 * perhaps undesireable default can (from 1.5.4) be changed by calling
1315 * png_set_alpha_mode (even if the alpha handling mode isn't required
1316 * or isn't changed from the default.)
1317 */
1318 png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
1319
1320 else /* neither are set */
1321 /* Just in case the following prevents any processing - file and screen
1322 * are both assumed to be linear and there is no way to introduce a
1323 * third gamma value other than png_set_background with 'UNIQUE', and,
1324 * prior to 1.5.4
1325 */
1326 png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
1327
1328 /* We have a gamma value now. */
1329 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
1330
1331 /* Now turn the gamma transformation on or off as appropriate. Notice
1332 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1333 * composition may independently cause gamma correction because it needs
1334 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1335 * hasn't been specified.) In any case this flag may get turned off in
1336 * the code immediately below if the transform can be handled outside the
1337 * row loop.
1338 */
1339 if (gamma_correction)
1340 png_ptr->transformations |= PNG_GAMMA;
1341
1342 else
1343 png_ptr->transformations &= ~PNG_GAMMA;
1344 }
1345 #endif
1346
1347 /* Certain transformations have the effect of preventing other
1348 * transformations that happen afterward in png_do_read_transformations,
1349 * resolve the interdependencies here. From the code of
1350 * png_do_read_transformations the order is:
1351 *
1352 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1353 * 2) PNG_STRIP_ALPHA (if no compose)
1354 * 3) PNG_RGB_TO_GRAY
1355 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1356 * 5) PNG_COMPOSE
1357 * 6) PNG_GAMMA
1358 * 7) PNG_STRIP_ALPHA (if compose)
1359 * 8) PNG_ENCODE_ALPHA
1360 * 9) PNG_SCALE_16_TO_8
1361 * 10) PNG_16_TO_8
1362 * 11) PNG_QUANTIZE (converts to palette)
1363 * 12) PNG_EXPAND_16
1364 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1365 * 14) PNG_INVERT_MONO
1366 * 15) PNG_INVERT_ALPHA
1367 * 16) PNG_SHIFT
1368 * 17) PNG_PACK
1369 * 18) PNG_BGR
1370 * 19) PNG_PACKSWAP
1371 * 20) PNG_FILLER (includes PNG_ADD_ALPHA)
1372 * 21) PNG_SWAP_ALPHA
1373 * 22) PNG_SWAP_BYTES
1374 * 23) PNG_USER_TRANSFORM [must be last]
1375 */
1376 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1377 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
1378 !(png_ptr->transformations & PNG_COMPOSE))
1379 {
1380 /* Stripping the alpha channel happens immediately after the 'expand'
1381 * transformations, before all other transformation, so it cancels out
1382 * the alpha handling. It has the side effect negating the effect of
1383 * PNG_EXPAND_tRNS too:
1384 */
1385 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
1386 PNG_EXPAND_tRNS);
1387 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1388
1389 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1390 * so transparency information would remain just so long as it wasn't
1391 * expanded. This produces unexpected API changes if the set of things
1392 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1393 * documentation - which says ask for what you want, accept what you
1394 * get.) This makes the behavior consistent from 1.5.4:
1395 */
1396 png_ptr->num_trans = 0;
1397 }
1398 #endif /* STRIP_ALPHA supported, no COMPOSE */
1399
1400 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1401 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1402 * settings will have no effect.
1403 */
1404 if (!png_gamma_significant(png_ptr->screen_gamma))
1405 {
1406 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1407 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1408 }
1409 #endif
1410
1411 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1412 /* Make sure the coefficients for the rgb to gray conversion are set
1413 * appropriately.
1414 */
1415 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
1416 png_colorspace_set_rgb_coefficients(png_ptr);
1417 #endif
1418
1419 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1420 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1421 /* Detect gray background and attempt to enable optimization for
1422 * gray --> RGB case.
1423 *
1424 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1425 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1426 * background color might actually be gray yet not be flagged as such.
1427 * This is not a problem for the current code, which uses
1428 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1429 * png_do_gray_to_rgb() transformation.
1430 *
1431 * TODO: this code needs to be revised to avoid the complexity and
1432 * interdependencies. The color type of the background should be recorded in
1433 * png_set_background, along with the bit depth, then the code has a record
1434 * of exactly what color space the background is currently in.
1435 */
1436 if (png_ptr->transformations & PNG_BACKGROUND_EXPAND)
1437 {
1438 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1439 * the file was grayscale the background value is gray.
1440 */
1441 if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
1442 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1443 }
1444
1445 else if (png_ptr->transformations & PNG_COMPOSE)
1446 {
1447 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1448 * so the color is in the color space of the output or png_set_alpha_mode
1449 * was called and the color is black. Ignore RGB_TO_GRAY because that
1450 * happens before GRAY_TO_RGB.
1451 */
1452 if (png_ptr->transformations & PNG_GRAY_TO_RGB)
1453 {
1454 if (png_ptr->background.red == png_ptr->background.green &&
1455 png_ptr->background.red == png_ptr->background.blue)
1456 {
1457 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1458 png_ptr->background.gray = png_ptr->background.red;
1459 }
1460 }
1461 }
1462 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
1463 #endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED */
1464
1465 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1466 * can be performed directly on the palette, and some (such as rgb to gray)
1467 * can be optimized inside the palette. This is particularly true of the
1468 * composite (background and alpha) stuff, which can be pretty much all done
1469 * in the palette even if the result is expanded to RGB or gray afterward.
1470 *
1471 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1472 * earlier and the palette stuff is actually handled on the first row. This
1473 * leads to the reported bug that the palette returned by png_get_PLTE is not
1474 * updated.
1475 */
1476 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1477 png_init_palette_transformations(png_ptr);
1478
1479 else
1480 png_init_rgb_transformations(png_ptr);
1481
1482 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1483 defined(PNG_READ_EXPAND_16_SUPPORTED)
1484 if ((png_ptr->transformations & PNG_EXPAND_16) &&
1485 (png_ptr->transformations & PNG_COMPOSE) &&
1486 !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1487 png_ptr->bit_depth != 16)
1488 {
1489 /* TODO: fix this. Because the expand_16 operation is after the compose
1490 * handling the background color must be 8, not 16, bits deep, but the
1491 * application will supply a 16-bit value so reduce it here.
1492 *
1493 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1494 * present, so that case is ok (until do_expand_16 is moved.)
1495 *
1496 * NOTE: this discards the low 16 bits of the user supplied background
1497 * color, but until expand_16 works properly there is no choice!
1498 */
1499 # define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
1500 CHOP(png_ptr->background.red);
1501 CHOP(png_ptr->background.green);
1502 CHOP(png_ptr->background.blue);
1503 CHOP(png_ptr->background.gray);
1504 # undef CHOP
1505 }
1506 #endif /* PNG_READ_BACKGROUND_SUPPORTED && PNG_READ_EXPAND_16_SUPPORTED */
1507
1508 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1509 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1510 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1511 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) &&
1512 (png_ptr->transformations & PNG_COMPOSE) &&
1513 !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1514 png_ptr->bit_depth == 16)
1515 {
1516 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1517 * component this will also happen after PNG_COMPOSE and so the background
1518 * color must be pre-expanded here.
1519 *
1520 * TODO: fix this too.
1521 */
1522 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
1523 png_ptr->background.green =
1524 (png_uint_16)(png_ptr->background.green * 257);
1525 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
1526 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
1527 }
1528 #endif
1529
1530 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1531 * background support (see the comments in scripts/pnglibconf.dfa), this
1532 * allows pre-multiplication of the alpha channel to be implemented as
1533 * compositing on black. This is probably sub-optimal and has been done in
1534 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1535 * implement the new API quickly, without lots of internal changes.)
1536 */
1537
1538 #ifdef PNG_READ_GAMMA_SUPPORTED
1539 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1540 /* Includes ALPHA_MODE */
1541 png_ptr->background_1 = png_ptr->background;
1542 # endif
1543
1544 /* This needs to change - in the palette image case a whole set of tables are
1545 * built when it would be quicker to just calculate the correct value for
1546 * each palette entry directly. Also, the test is too tricky - why check
1547 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1548 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1549 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1550 * the gamma tables will not be built even if composition is required on a
1551 * gamma encoded value.
1552 *
1553 * In 1.5.4 this is addressed below by an additional check on the individual
1554 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1555 * tables.
1556 */
1557 if ((png_ptr->transformations & PNG_GAMMA)
1558 || ((png_ptr->transformations & PNG_RGB_TO_GRAY)
1559 && (png_gamma_significant(png_ptr->colorspace.gamma) ||
1560 png_gamma_significant(png_ptr->screen_gamma)))
1561 || ((png_ptr->transformations & PNG_COMPOSE)
1562 && (png_gamma_significant(png_ptr->colorspace.gamma)
1563 || png_gamma_significant(png_ptr->screen_gamma)
1564 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1565 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE
1566 && png_gamma_significant(png_ptr->background_gamma))
1567 # endif
1568 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA)
1569 && png_gamma_significant(png_ptr->screen_gamma))
1570 )
1571 {
1572 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
1573
1574 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1575 if (png_ptr->transformations & PNG_COMPOSE)
1576 {
1577 /* Issue a warning about this combination: because RGB_TO_GRAY is
1578 * optimized to do the gamma transform if present yet do_background has
1579 * to do the same thing if both options are set a
1580 * double-gamma-correction happens. This is true in all versions of
1581 * libpng to date.
1582 */
1583 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
1584 png_warning(png_ptr,
1585 "libpng does not support gamma+background+rgb_to_gray");
1586
1587 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1588 {
1589 /* We don't get to here unless there is a tRNS chunk with non-opaque
1590 * entries - see the checking code at the start of this function.
1591 */
1592 png_color back, back_1;
1593 png_colorp palette = png_ptr->palette;
1594 int num_palette = png_ptr->num_palette;
1595 int i;
1596 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
1597 {
1598
1599 back.red = png_ptr->gamma_table[png_ptr->background.red];
1600 back.green = png_ptr->gamma_table[png_ptr->background.green];
1601 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
1602
1603 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
1604 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
1605 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
1606 }
1607 else
1608 {
1609 png_fixed_point g, gs;
1610
1611 switch (png_ptr->background_gamma_type)
1612 {
1613 case PNG_BACKGROUND_GAMMA_SCREEN:
1614 g = (png_ptr->screen_gamma);
1615 gs = PNG_FP_1;
1616 break;
1617
1618 case PNG_BACKGROUND_GAMMA_FILE:
1619 g = png_reciprocal(png_ptr->colorspace.gamma);
1620 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1621 png_ptr->screen_gamma);
1622 break;
1623
1624 case PNG_BACKGROUND_GAMMA_UNIQUE:
1625 g = png_reciprocal(png_ptr->background_gamma);
1626 gs = png_reciprocal2(png_ptr->background_gamma,
1627 png_ptr->screen_gamma);
1628 break;
1629 default:
1630 g = PNG_FP_1; /* back_1 */
1631 gs = PNG_FP_1; /* back */
1632 break;
1633 }
1634
1635 if (png_gamma_significant(gs))
1636 {
1637 back.red = png_gamma_8bit_correct(png_ptr->background.red,
1638 gs);
1639 back.green = png_gamma_8bit_correct(png_ptr->background.green,
1640 gs);
1641 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1642 gs);
1643 }
1644
1645 else
1646 {
1647 back.red = (png_byte)png_ptr->background.red;
1648 back.green = (png_byte)png_ptr->background.green;
1649 back.blue = (png_byte)png_ptr->background.blue;
1650 }
1651
1652 if (png_gamma_significant(g))
1653 {
1654 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
1655 g);
1656 back_1.green = png_gamma_8bit_correct(
1657 png_ptr->background.green, g);
1658 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1659 g);
1660 }
1661
1662 else
1663 {
1664 back_1.red = (png_byte)png_ptr->background.red;
1665 back_1.green = (png_byte)png_ptr->background.green;
1666 back_1.blue = (png_byte)png_ptr->background.blue;
1667 }
1668 }
1669
1670 for (i = 0; i < num_palette; i++)
1671 {
1672 if (i < (int)png_ptr->num_trans &&
1673 png_ptr->trans_alpha[i] != 0xff)
1674 {
1675 if (png_ptr->trans_alpha[i] == 0)
1676 {
1677 palette[i] = back;
1678 }
1679 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1680 {
1681 png_byte v, w;
1682
1683 v = png_ptr->gamma_to_1[palette[i].red];
1684 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
1685 palette[i].red = png_ptr->gamma_from_1[w];
1686
1687 v = png_ptr->gamma_to_1[palette[i].green];
1688 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
1689 palette[i].green = png_ptr->gamma_from_1[w];
1690
1691 v = png_ptr->gamma_to_1[palette[i].blue];
1692 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
1693 palette[i].blue = png_ptr->gamma_from_1[w];
1694 }
1695 }
1696 else
1697 {
1698 palette[i].red = png_ptr->gamma_table[palette[i].red];
1699 palette[i].green = png_ptr->gamma_table[palette[i].green];
1700 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1701 }
1702 }
1703
1704 /* Prevent the transformations being done again.
1705 *
1706 * NOTE: this is highly dubious; it removes the transformations in
1707 * place. This seems inconsistent with the general treatment of the
1708 * transformations elsewhere.
1709 */
1710 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
1711 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1712
1713 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1714 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1715 {
1716 int gs_sig, g_sig;
1717 png_fixed_point g = PNG_FP_1; /* Correction to linear */
1718 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
1719
1720 switch (png_ptr->background_gamma_type)
1721 {
1722 case PNG_BACKGROUND_GAMMA_SCREEN:
1723 g = png_ptr->screen_gamma;
1724 /* gs = PNG_FP_1; */
1725 break;
1726
1727 case PNG_BACKGROUND_GAMMA_FILE:
1728 g = png_reciprocal(png_ptr->colorspace.gamma);
1729 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1730 png_ptr->screen_gamma);
1731 break;
1732
1733 case PNG_BACKGROUND_GAMMA_UNIQUE:
1734 g = png_reciprocal(png_ptr->background_gamma);
1735 gs = png_reciprocal2(png_ptr->background_gamma,
1736 png_ptr->screen_gamma);
1737 break;
1738
1739 default:
1740 png_error(png_ptr, "invalid background gamma type");
1741 }
1742
1743 g_sig = png_gamma_significant(g);
1744 gs_sig = png_gamma_significant(gs);
1745
1746 if (g_sig)
1747 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
1748 png_ptr->background.gray, g);
1749
1750 if (gs_sig)
1751 png_ptr->background.gray = png_gamma_correct(png_ptr,
1752 png_ptr->background.gray, gs);
1753
1754 if ((png_ptr->background.red != png_ptr->background.green) ||
1755 (png_ptr->background.red != png_ptr->background.blue) ||
1756 (png_ptr->background.red != png_ptr->background.gray))
1757 {
1758 /* RGB or RGBA with color background */
1759 if (g_sig)
1760 {
1761 png_ptr->background_1.red = png_gamma_correct(png_ptr,
1762 png_ptr->background.red, g);
1763
1764 png_ptr->background_1.green = png_gamma_correct(png_ptr,
1765 png_ptr->background.green, g);
1766
1767 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
1768 png_ptr->background.blue, g);
1769 }
1770
1771 if (gs_sig)
1772 {
1773 png_ptr->background.red = png_gamma_correct(png_ptr,
1774 png_ptr->background.red, gs);
1775
1776 png_ptr->background.green = png_gamma_correct(png_ptr,
1777 png_ptr->background.green, gs);
1778
1779 png_ptr->background.blue = png_gamma_correct(png_ptr,
1780 png_ptr->background.blue, gs);
1781 }
1782 }
1783
1784 else
1785 {
1786 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1787 png_ptr->background_1.red = png_ptr->background_1.green
1788 = png_ptr->background_1.blue = png_ptr->background_1.gray;
1789
1790 png_ptr->background.red = png_ptr->background.green
1791 = png_ptr->background.blue = png_ptr->background.gray;
1792 }
1793
1794 /* The background is now in screen gamma: */
1795 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
1796 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1797 }/* png_ptr->transformations & PNG_BACKGROUND */
1798
1799 else
1800 /* Transformation does not include PNG_BACKGROUND */
1801 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
1802 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
1803 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1804 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1805 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
1806 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
1807 #endif
1808 )
1809 {
1810 png_colorp palette = png_ptr->palette;
1811 int num_palette = png_ptr->num_palette;
1812 int i;
1813
1814 /* NOTE: there are other transformations that should probably be in
1815 * here too.
1816 */
1817 for (i = 0; i < num_palette; i++)
1818 {
1819 palette[i].red = png_ptr->gamma_table[palette[i].red];
1820 palette[i].green = png_ptr->gamma_table[palette[i].green];
1821 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1822 }
1823
1824 /* Done the gamma correction. */
1825 png_ptr->transformations &= ~PNG_GAMMA;
1826 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1827 }
1828 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1829 else
1830 #endif
1831 #endif /* PNG_READ_GAMMA_SUPPORTED */
1832
1833 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1834 /* No GAMMA transformation (see the hanging else 4 lines above) */
1835 if ((png_ptr->transformations & PNG_COMPOSE) &&
1836 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1837 {
1838 int i;
1839 int istop = (int)png_ptr->num_trans;
1840 png_color back;
1841 png_colorp palette = png_ptr->palette;
1842
1843 back.red = (png_byte)png_ptr->background.red;
1844 back.green = (png_byte)png_ptr->background.green;
1845 back.blue = (png_byte)png_ptr->background.blue;
1846
1847 for (i = 0; i < istop; i++)
1848 {
1849 if (png_ptr->trans_alpha[i] == 0)
1850 {
1851 palette[i] = back;
1852 }
1853
1854 else if (png_ptr->trans_alpha[i] != 0xff)
1855 {
1856 /* The png_composite() macro is defined in png.h */
1857 png_composite(palette[i].red, palette[i].red,
1858 png_ptr->trans_alpha[i], back.red);
1859
1860 png_composite(palette[i].green, palette[i].green,
1861 png_ptr->trans_alpha[i], back.green);
1862
1863 png_composite(palette[i].blue, palette[i].blue,
1864 png_ptr->trans_alpha[i], back.blue);
1865 }
1866 }
1867
1868 png_ptr->transformations &= ~PNG_COMPOSE;
1869 }
1870 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
1871
1872 #ifdef PNG_READ_SHIFT_SUPPORTED
1873 if ((png_ptr->transformations & PNG_SHIFT) &&
1874 !(png_ptr->transformations & PNG_EXPAND) &&
1875 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1876 {
1877 int i;
1878 int istop = png_ptr->num_palette;
1879 int shift = 8 - png_ptr->sig_bit.red;
1880
1881 png_ptr->transformations &= ~PNG_SHIFT;
1882
1883 /* significant bits can be in the range 1 to 7 for a meaninful result, if
1884 * the number of significant bits is 0 then no shift is done (this is an
1885 * error condition which is silently ignored.)
1886 */
1887 if (shift > 0 && shift < 8)
1888 for (i=0; i<istop; ++i)
1889 {
1890 int component = png_ptr->palette[i].red;
1891
1892 component >>= shift;
1893 png_ptr->palette[i].red = (png_byte)component;
1894 }
1895
1896 shift = 8 - png_ptr->sig_bit.green;
1897 if (shift > 0 && shift < 8)
1898 for (i=0; i<istop; ++i)
1899 {
1900 int component = png_ptr->palette[i].green;
1901
1902 component >>= shift;
1903 png_ptr->palette[i].green = (png_byte)component;
1904 }
1905
1906 shift = 8 - png_ptr->sig_bit.blue;
1907 if (shift > 0 && shift < 8)
1908 for (i=0; i<istop; ++i)
1909 {
1910 int component = png_ptr->palette[i].blue;
1911
1912 component >>= shift;
1913 png_ptr->palette[i].blue = (png_byte)component;
1914 }
1915 }
1916 #endif /* PNG_READ_SHIFT_SUPPORTED */
1917 }
1918
1919 /* Modify the info structure to reflect the transformations. The
1920 * info should be updated so a PNG file could be written with it,
1921 * assuming the transformations result in valid PNG data.
1922 */
1923 void /* PRIVATE */
png_read_transform_info(png_structrp png_ptr,png_inforp info_ptr)1924 png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
1925 {
1926 png_debug(1, "in png_read_transform_info");
1927
1928 #ifdef PNG_READ_EXPAND_SUPPORTED
1929 if (png_ptr->transformations & PNG_EXPAND)
1930 {
1931 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1932 {
1933 /* This check must match what actually happens in
1934 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1935 * it is all opaque we must do the same (at present it does not.)
1936 */
1937 if (png_ptr->num_trans > 0)
1938 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
1939
1940 else
1941 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
1942
1943 info_ptr->bit_depth = 8;
1944 info_ptr->num_trans = 0;
1945
1946 if (png_ptr->palette == NULL)
1947 png_error (png_ptr, "Palette is NULL in indexed image");
1948 }
1949 else
1950 {
1951 if (png_ptr->num_trans)
1952 {
1953 if (png_ptr->transformations & PNG_EXPAND_tRNS)
1954 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
1955 }
1956 if (info_ptr->bit_depth < 8)
1957 info_ptr->bit_depth = 8;
1958
1959 info_ptr->num_trans = 0;
1960 }
1961 }
1962 #endif
1963
1964 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
1965 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1966 /* The following is almost certainly wrong unless the background value is in
1967 * the screen space!
1968 */
1969 if (png_ptr->transformations & PNG_COMPOSE)
1970 info_ptr->background = png_ptr->background;
1971 #endif
1972
1973 #ifdef PNG_READ_GAMMA_SUPPORTED
1974 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
1975 * however it seems that the code in png_init_read_transformations, which has
1976 * been called before this from png_read_update_info->png_read_start_row
1977 * sometimes does the gamma transform and cancels the flag.
1978 *
1979 * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
1980 * the screen_gamma value. The following probably results in weirdness if
1981 * the info_ptr is used by the app after the rows have been read.
1982 */
1983 info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
1984 #endif
1985
1986 if (info_ptr->bit_depth == 16)
1987 {
1988 # ifdef PNG_READ_16BIT_SUPPORTED
1989 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1990 if (png_ptr->transformations & PNG_SCALE_16_TO_8)
1991 info_ptr->bit_depth = 8;
1992 # endif
1993
1994 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1995 if (png_ptr->transformations & PNG_16_TO_8)
1996 info_ptr->bit_depth = 8;
1997 # endif
1998
1999 # else
2000 /* No 16 bit support: force chopping 16-bit input down to 8, in this case
2001 * the app program can chose if both APIs are available by setting the
2002 * correct scaling to use.
2003 */
2004 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2005 /* For compatibility with previous versions use the strip method by
2006 * default. This code works because if PNG_SCALE_16_TO_8 is already
2007 * set the code below will do that in preference to the chop.
2008 */
2009 png_ptr->transformations |= PNG_16_TO_8;
2010 info_ptr->bit_depth = 8;
2011 # else
2012
2013 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2014 png_ptr->transformations |= PNG_SCALE_16_TO_8;
2015 info_ptr->bit_depth = 8;
2016 # else
2017
2018 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
2019 # endif
2020 # endif
2021 #endif /* !READ_16BIT_SUPPORTED */
2022 }
2023
2024 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2025 if (png_ptr->transformations & PNG_GRAY_TO_RGB)
2026 info_ptr->color_type = (png_byte)(info_ptr->color_type |
2027 PNG_COLOR_MASK_COLOR);
2028 #endif
2029
2030 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2031 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
2032 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2033 ~PNG_COLOR_MASK_COLOR);
2034 #endif
2035
2036 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2037 if (png_ptr->transformations & PNG_QUANTIZE)
2038 {
2039 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2040 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
2041 png_ptr->palette_lookup && info_ptr->bit_depth == 8)
2042 {
2043 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
2044 }
2045 }
2046 #endif
2047
2048 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2049 if (png_ptr->transformations & PNG_EXPAND_16 && info_ptr->bit_depth == 8 &&
2050 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
2051 {
2052 info_ptr->bit_depth = 16;
2053 }
2054 #endif
2055
2056 #ifdef PNG_READ_PACK_SUPPORTED
2057 if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8))
2058 info_ptr->bit_depth = 8;
2059 #endif
2060
2061 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
2062 info_ptr->channels = 1;
2063
2064 else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
2065 info_ptr->channels = 3;
2066
2067 else
2068 info_ptr->channels = 1;
2069
2070 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2071 if (png_ptr->transformations & PNG_STRIP_ALPHA)
2072 {
2073 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2074 ~PNG_COLOR_MASK_ALPHA);
2075 info_ptr->num_trans = 0;
2076 }
2077 #endif
2078
2079 if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
2080 info_ptr->channels++;
2081
2082 #ifdef PNG_READ_FILLER_SUPPORTED
2083 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2084 if ((png_ptr->transformations & PNG_FILLER) &&
2085 ((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2086 (info_ptr->color_type == PNG_COLOR_TYPE_GRAY)))
2087 {
2088 info_ptr->channels++;
2089 /* If adding a true alpha channel not just filler */
2090 if (png_ptr->transformations & PNG_ADD_ALPHA)
2091 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
2092 }
2093 #endif
2094
2095 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2096 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2097 if (png_ptr->transformations & PNG_USER_TRANSFORM)
2098 {
2099 if (info_ptr->bit_depth < png_ptr->user_transform_depth)
2100 info_ptr->bit_depth = png_ptr->user_transform_depth;
2101
2102 if (info_ptr->channels < png_ptr->user_transform_channels)
2103 info_ptr->channels = png_ptr->user_transform_channels;
2104 }
2105 #endif
2106
2107 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
2108 info_ptr->bit_depth);
2109
2110 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
2111
2112 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2113 * check in png_rowbytes that the user buffer won't get overwritten. Note
2114 * that the field is not always set - if png_read_update_info isn't called
2115 * the application has to either not do any transforms or get the calculation
2116 * right itself.
2117 */
2118 png_ptr->info_rowbytes = info_ptr->rowbytes;
2119
2120 #ifndef PNG_READ_EXPAND_SUPPORTED
2121 if (png_ptr)
2122 return;
2123 #endif
2124 }
2125
2126 #ifdef PNG_READ_PACK_SUPPORTED
2127 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2128 * without changing the actual values. Thus, if you had a row with
2129 * a bit depth of 1, you would end up with bytes that only contained
2130 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2131 * png_do_shift() after this.
2132 */
2133 static void
png_do_unpack(png_row_infop row_info,png_bytep row)2134 png_do_unpack(png_row_infop row_info, png_bytep row)
2135 {
2136 png_debug(1, "in png_do_unpack");
2137
2138 if (row_info->bit_depth < 8)
2139 {
2140 png_uint_32 i;
2141 png_uint_32 row_width=row_info->width;
2142
2143 switch (row_info->bit_depth)
2144 {
2145 case 1:
2146 {
2147 png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
2148 png_bytep dp = row + (png_size_t)row_width - 1;
2149 png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
2150 for (i = 0; i < row_width; i++)
2151 {
2152 *dp = (png_byte)((*sp >> shift) & 0x01);
2153
2154 if (shift == 7)
2155 {
2156 shift = 0;
2157 sp--;
2158 }
2159
2160 else
2161 shift++;
2162
2163 dp--;
2164 }
2165 break;
2166 }
2167
2168 case 2:
2169 {
2170
2171 png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
2172 png_bytep dp = row + (png_size_t)row_width - 1;
2173 png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
2174 for (i = 0; i < row_width; i++)
2175 {
2176 *dp = (png_byte)((*sp >> shift) & 0x03);
2177
2178 if (shift == 6)
2179 {
2180 shift = 0;
2181 sp--;
2182 }
2183
2184 else
2185 shift += 2;
2186
2187 dp--;
2188 }
2189 break;
2190 }
2191
2192 case 4:
2193 {
2194 png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
2195 png_bytep dp = row + (png_size_t)row_width - 1;
2196 png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
2197 for (i = 0; i < row_width; i++)
2198 {
2199 *dp = (png_byte)((*sp >> shift) & 0x0f);
2200
2201 if (shift == 4)
2202 {
2203 shift = 0;
2204 sp--;
2205 }
2206
2207 else
2208 shift = 4;
2209
2210 dp--;
2211 }
2212 break;
2213 }
2214
2215 default:
2216 break;
2217 }
2218 row_info->bit_depth = 8;
2219 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2220 row_info->rowbytes = row_width * row_info->channels;
2221 }
2222 }
2223 #endif
2224
2225 #ifdef PNG_READ_SHIFT_SUPPORTED
2226 /* Reverse the effects of png_do_shift. This routine merely shifts the
2227 * pixels back to their significant bits values. Thus, if you have
2228 * a row of bit depth 8, but only 5 are significant, this will shift
2229 * the values back to 0 through 31.
2230 */
2231 static void
png_do_unshift(png_row_infop row_info,png_bytep row,png_const_color_8p sig_bits)2232 png_do_unshift(png_row_infop row_info, png_bytep row,
2233 png_const_color_8p sig_bits)
2234 {
2235 int color_type;
2236
2237 png_debug(1, "in png_do_unshift");
2238
2239 /* The palette case has already been handled in the _init routine. */
2240 color_type = row_info->color_type;
2241
2242 if (color_type != PNG_COLOR_TYPE_PALETTE)
2243 {
2244 int shift[4];
2245 int channels = 0;
2246 int bit_depth = row_info->bit_depth;
2247
2248 if (color_type & PNG_COLOR_MASK_COLOR)
2249 {
2250 shift[channels++] = bit_depth - sig_bits->red;
2251 shift[channels++] = bit_depth - sig_bits->green;
2252 shift[channels++] = bit_depth - sig_bits->blue;
2253 }
2254
2255 else
2256 {
2257 shift[channels++] = bit_depth - sig_bits->gray;
2258 }
2259
2260 if (color_type & PNG_COLOR_MASK_ALPHA)
2261 {
2262 shift[channels++] = bit_depth - sig_bits->alpha;
2263 }
2264
2265 {
2266 int c, have_shift;
2267
2268 for (c = have_shift = 0; c < channels; ++c)
2269 {
2270 /* A shift of more than the bit depth is an error condition but it
2271 * gets ignored here.
2272 */
2273 if (shift[c] <= 0 || shift[c] >= bit_depth)
2274 shift[c] = 0;
2275
2276 else
2277 have_shift = 1;
2278 }
2279
2280 if (!have_shift)
2281 return;
2282 }
2283
2284 switch (bit_depth)
2285 {
2286 default:
2287 /* Must be 1bpp gray: should not be here! */
2288 /* NOTREACHED */
2289 break;
2290
2291 case 2:
2292 /* Must be 2bpp gray */
2293 /* assert(channels == 1 && shift[0] == 1) */
2294 {
2295 png_bytep bp = row;
2296 png_bytep bp_end = bp + row_info->rowbytes;
2297
2298 while (bp < bp_end)
2299 {
2300 int b = (*bp >> 1) & 0x55;
2301 *bp++ = (png_byte)b;
2302 }
2303 break;
2304 }
2305
2306 case 4:
2307 /* Must be 4bpp gray */
2308 /* assert(channels == 1) */
2309 {
2310 png_bytep bp = row;
2311 png_bytep bp_end = bp + row_info->rowbytes;
2312 int gray_shift = shift[0];
2313 int mask = 0xf >> gray_shift;
2314
2315 mask |= mask << 4;
2316
2317 while (bp < bp_end)
2318 {
2319 int b = (*bp >> gray_shift) & mask;
2320 *bp++ = (png_byte)b;
2321 }
2322 break;
2323 }
2324
2325 case 8:
2326 /* Single byte components, G, GA, RGB, RGBA */
2327 {
2328 png_bytep bp = row;
2329 png_bytep bp_end = bp + row_info->rowbytes;
2330 int channel = 0;
2331
2332 while (bp < bp_end)
2333 {
2334 int b = *bp >> shift[channel];
2335 if (++channel >= channels)
2336 channel = 0;
2337 *bp++ = (png_byte)b;
2338 }
2339 break;
2340 }
2341
2342 #ifdef PNG_READ_16BIT_SUPPORTED
2343 case 16:
2344 /* Double byte components, G, GA, RGB, RGBA */
2345 {
2346 png_bytep bp = row;
2347 png_bytep bp_end = bp + row_info->rowbytes;
2348 int channel = 0;
2349
2350 while (bp < bp_end)
2351 {
2352 int value = (bp[0] << 8) + bp[1];
2353
2354 value >>= shift[channel];
2355 if (++channel >= channels)
2356 channel = 0;
2357 *bp++ = (png_byte)(value >> 8);
2358 *bp++ = (png_byte)(value & 0xff);
2359 }
2360 break;
2361 }
2362 #endif
2363 }
2364 }
2365 }
2366 #endif
2367
2368 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2369 /* Scale rows of bit depth 16 down to 8 accurately */
2370 static void
png_do_scale_16_to_8(png_row_infop row_info,png_bytep row)2371 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
2372 {
2373 png_debug(1, "in png_do_scale_16_to_8");
2374
2375 if (row_info->bit_depth == 16)
2376 {
2377 png_bytep sp = row; /* source */
2378 png_bytep dp = row; /* destination */
2379 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2380
2381 while (sp < ep)
2382 {
2383 /* The input is an array of 16 bit components, these must be scaled to
2384 * 8 bits each. For a 16 bit value V the required value (from the PNG
2385 * specification) is:
2386 *
2387 * (V * 255) / 65535
2388 *
2389 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2390 *
2391 * Represent V as the two byte value vhi.vlo. Make a guess that the
2392 * result is the top byte of V, vhi, then the correction to this value
2393 * is:
2394 *
2395 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2396 * = floor(((vlo-vhi) + 128.5) / 257)
2397 *
2398 * This can be approximated using integer arithmetic (and a signed
2399 * shift):
2400 *
2401 * error = (vlo-vhi+128) >> 8;
2402 *
2403 * The approximate differs from the exact answer only when (vlo-vhi) is
2404 * 128; it then gives a correction of +1 when the exact correction is
2405 * 0. This gives 128 errors. The exact answer (correct for all 16 bit
2406 * input values) is:
2407 *
2408 * error = (vlo-vhi+128)*65535 >> 24;
2409 *
2410 * An alternative arithmetic calculation which also gives no errors is:
2411 *
2412 * (V * 255 + 32895) >> 16
2413 */
2414
2415 png_int_32 tmp = *sp++; /* must be signed! */
2416 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
2417 *dp++ = (png_byte)tmp;
2418 }
2419
2420 row_info->bit_depth = 8;
2421 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2422 row_info->rowbytes = row_info->width * row_info->channels;
2423 }
2424 }
2425 #endif
2426
2427 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2428 static void
2429 /* Simply discard the low byte. This was the default behavior prior
2430 * to libpng-1.5.4.
2431 */
png_do_chop(png_row_infop row_info,png_bytep row)2432 png_do_chop(png_row_infop row_info, png_bytep row)
2433 {
2434 png_debug(1, "in png_do_chop");
2435
2436 if (row_info->bit_depth == 16)
2437 {
2438 png_bytep sp = row; /* source */
2439 png_bytep dp = row; /* destination */
2440 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2441
2442 while (sp < ep)
2443 {
2444 *dp++ = *sp;
2445 sp += 2; /* skip low byte */
2446 }
2447
2448 row_info->bit_depth = 8;
2449 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2450 row_info->rowbytes = row_info->width * row_info->channels;
2451 }
2452 }
2453 #endif
2454
2455 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2456 static void
png_do_read_swap_alpha(png_row_infop row_info,png_bytep row)2457 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
2458 {
2459 png_debug(1, "in png_do_read_swap_alpha");
2460
2461 {
2462 png_uint_32 row_width = row_info->width;
2463 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2464 {
2465 /* This converts from RGBA to ARGB */
2466 if (row_info->bit_depth == 8)
2467 {
2468 png_bytep sp = row + row_info->rowbytes;
2469 png_bytep dp = sp;
2470 png_byte save;
2471 png_uint_32 i;
2472
2473 for (i = 0; i < row_width; i++)
2474 {
2475 save = *(--sp);
2476 *(--dp) = *(--sp);
2477 *(--dp) = *(--sp);
2478 *(--dp) = *(--sp);
2479 *(--dp) = save;
2480 }
2481 }
2482
2483 #ifdef PNG_READ_16BIT_SUPPORTED
2484 /* This converts from RRGGBBAA to AARRGGBB */
2485 else
2486 {
2487 png_bytep sp = row + row_info->rowbytes;
2488 png_bytep dp = sp;
2489 png_byte save[2];
2490 png_uint_32 i;
2491
2492 for (i = 0; i < row_width; i++)
2493 {
2494 save[0] = *(--sp);
2495 save[1] = *(--sp);
2496 *(--dp) = *(--sp);
2497 *(--dp) = *(--sp);
2498 *(--dp) = *(--sp);
2499 *(--dp) = *(--sp);
2500 *(--dp) = *(--sp);
2501 *(--dp) = *(--sp);
2502 *(--dp) = save[0];
2503 *(--dp) = save[1];
2504 }
2505 }
2506 #endif
2507 }
2508
2509 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2510 {
2511 /* This converts from GA to AG */
2512 if (row_info->bit_depth == 8)
2513 {
2514 png_bytep sp = row + row_info->rowbytes;
2515 png_bytep dp = sp;
2516 png_byte save;
2517 png_uint_32 i;
2518
2519 for (i = 0; i < row_width; i++)
2520 {
2521 save = *(--sp);
2522 *(--dp) = *(--sp);
2523 *(--dp) = save;
2524 }
2525 }
2526
2527 #ifdef PNG_READ_16BIT_SUPPORTED
2528 /* This converts from GGAA to AAGG */
2529 else
2530 {
2531 png_bytep sp = row + row_info->rowbytes;
2532 png_bytep dp = sp;
2533 png_byte save[2];
2534 png_uint_32 i;
2535
2536 for (i = 0; i < row_width; i++)
2537 {
2538 save[0] = *(--sp);
2539 save[1] = *(--sp);
2540 *(--dp) = *(--sp);
2541 *(--dp) = *(--sp);
2542 *(--dp) = save[0];
2543 *(--dp) = save[1];
2544 }
2545 }
2546 #endif
2547 }
2548 }
2549 }
2550 #endif
2551
2552 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2553 static void
png_do_read_invert_alpha(png_row_infop row_info,png_bytep row)2554 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
2555 {
2556 png_uint_32 row_width;
2557 png_debug(1, "in png_do_read_invert_alpha");
2558
2559 row_width = row_info->width;
2560 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2561 {
2562 if (row_info->bit_depth == 8)
2563 {
2564 /* This inverts the alpha channel in RGBA */
2565 png_bytep sp = row + row_info->rowbytes;
2566 png_bytep dp = sp;
2567 png_uint_32 i;
2568
2569 for (i = 0; i < row_width; i++)
2570 {
2571 *(--dp) = (png_byte)(255 - *(--sp));
2572
2573 /* This does nothing:
2574 *(--dp) = *(--sp);
2575 *(--dp) = *(--sp);
2576 *(--dp) = *(--sp);
2577 We can replace it with:
2578 */
2579 sp-=3;
2580 dp=sp;
2581 }
2582 }
2583
2584 #ifdef PNG_READ_16BIT_SUPPORTED
2585 /* This inverts the alpha channel in RRGGBBAA */
2586 else
2587 {
2588 png_bytep sp = row + row_info->rowbytes;
2589 png_bytep dp = sp;
2590 png_uint_32 i;
2591
2592 for (i = 0; i < row_width; i++)
2593 {
2594 *(--dp) = (png_byte)(255 - *(--sp));
2595 *(--dp) = (png_byte)(255 - *(--sp));
2596
2597 /* This does nothing:
2598 *(--dp) = *(--sp);
2599 *(--dp) = *(--sp);
2600 *(--dp) = *(--sp);
2601 *(--dp) = *(--sp);
2602 *(--dp) = *(--sp);
2603 *(--dp) = *(--sp);
2604 We can replace it with:
2605 */
2606 sp-=6;
2607 dp=sp;
2608 }
2609 }
2610 #endif
2611 }
2612 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2613 {
2614 if (row_info->bit_depth == 8)
2615 {
2616 /* This inverts the alpha channel in GA */
2617 png_bytep sp = row + row_info->rowbytes;
2618 png_bytep dp = sp;
2619 png_uint_32 i;
2620
2621 for (i = 0; i < row_width; i++)
2622 {
2623 *(--dp) = (png_byte)(255 - *(--sp));
2624 *(--dp) = *(--sp);
2625 }
2626 }
2627
2628 #ifdef PNG_READ_16BIT_SUPPORTED
2629 else
2630 {
2631 /* This inverts the alpha channel in GGAA */
2632 png_bytep sp = row + row_info->rowbytes;
2633 png_bytep dp = sp;
2634 png_uint_32 i;
2635
2636 for (i = 0; i < row_width; i++)
2637 {
2638 *(--dp) = (png_byte)(255 - *(--sp));
2639 *(--dp) = (png_byte)(255 - *(--sp));
2640 /*
2641 *(--dp) = *(--sp);
2642 *(--dp) = *(--sp);
2643 */
2644 sp-=2;
2645 dp=sp;
2646 }
2647 }
2648 #endif
2649 }
2650 }
2651 #endif
2652
2653 #ifdef PNG_READ_FILLER_SUPPORTED
2654 /* Add filler channel if we have RGB color */
2655 static void
png_do_read_filler(png_row_infop row_info,png_bytep row,png_uint_32 filler,png_uint_32 flags)2656 png_do_read_filler(png_row_infop row_info, png_bytep row,
2657 png_uint_32 filler, png_uint_32 flags)
2658 {
2659 png_uint_32 i;
2660 png_uint_32 row_width = row_info->width;
2661
2662 #ifdef PNG_READ_16BIT_SUPPORTED
2663 png_byte hi_filler = (png_byte)((filler>>8) & 0xff);
2664 #endif
2665 png_byte lo_filler = (png_byte)(filler & 0xff);
2666
2667 png_debug(1, "in png_do_read_filler");
2668
2669 if (
2670 row_info->color_type == PNG_COLOR_TYPE_GRAY)
2671 {
2672 if (row_info->bit_depth == 8)
2673 {
2674 if (flags & PNG_FLAG_FILLER_AFTER)
2675 {
2676 /* This changes the data from G to GX */
2677 png_bytep sp = row + (png_size_t)row_width;
2678 png_bytep dp = sp + (png_size_t)row_width;
2679 for (i = 1; i < row_width; i++)
2680 {
2681 *(--dp) = lo_filler;
2682 *(--dp) = *(--sp);
2683 }
2684 *(--dp) = lo_filler;
2685 row_info->channels = 2;
2686 row_info->pixel_depth = 16;
2687 row_info->rowbytes = row_width * 2;
2688 }
2689
2690 else
2691 {
2692 /* This changes the data from G to XG */
2693 png_bytep sp = row + (png_size_t)row_width;
2694 png_bytep dp = sp + (png_size_t)row_width;
2695 for (i = 0; i < row_width; i++)
2696 {
2697 *(--dp) = *(--sp);
2698 *(--dp) = lo_filler;
2699 }
2700 row_info->channels = 2;
2701 row_info->pixel_depth = 16;
2702 row_info->rowbytes = row_width * 2;
2703 }
2704 }
2705
2706 #ifdef PNG_READ_16BIT_SUPPORTED
2707 else if (row_info->bit_depth == 16)
2708 {
2709 if (flags & PNG_FLAG_FILLER_AFTER)
2710 {
2711 /* This changes the data from GG to GGXX */
2712 png_bytep sp = row + (png_size_t)row_width * 2;
2713 png_bytep dp = sp + (png_size_t)row_width * 2;
2714 for (i = 1; i < row_width; i++)
2715 {
2716 *(--dp) = hi_filler;
2717 *(--dp) = lo_filler;
2718 *(--dp) = *(--sp);
2719 *(--dp) = *(--sp);
2720 }
2721 *(--dp) = hi_filler;
2722 *(--dp) = lo_filler;
2723 row_info->channels = 2;
2724 row_info->pixel_depth = 32;
2725 row_info->rowbytes = row_width * 4;
2726 }
2727
2728 else
2729 {
2730 /* This changes the data from GG to XXGG */
2731 png_bytep sp = row + (png_size_t)row_width * 2;
2732 png_bytep dp = sp + (png_size_t)row_width * 2;
2733 for (i = 0; i < row_width; i++)
2734 {
2735 *(--dp) = *(--sp);
2736 *(--dp) = *(--sp);
2737 *(--dp) = hi_filler;
2738 *(--dp) = lo_filler;
2739 }
2740 row_info->channels = 2;
2741 row_info->pixel_depth = 32;
2742 row_info->rowbytes = row_width * 4;
2743 }
2744 }
2745 #endif
2746 } /* COLOR_TYPE == GRAY */
2747 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
2748 {
2749 if (row_info->bit_depth == 8)
2750 {
2751 if (flags & PNG_FLAG_FILLER_AFTER)
2752 {
2753 /* This changes the data from RGB to RGBX */
2754 png_bytep sp = row + (png_size_t)row_width * 3;
2755 png_bytep dp = sp + (png_size_t)row_width;
2756 for (i = 1; i < row_width; i++)
2757 {
2758 *(--dp) = lo_filler;
2759 *(--dp) = *(--sp);
2760 *(--dp) = *(--sp);
2761 *(--dp) = *(--sp);
2762 }
2763 *(--dp) = lo_filler;
2764 row_info->channels = 4;
2765 row_info->pixel_depth = 32;
2766 row_info->rowbytes = row_width * 4;
2767 }
2768
2769 else
2770 {
2771 /* This changes the data from RGB to XRGB */
2772 png_bytep sp = row + (png_size_t)row_width * 3;
2773 png_bytep dp = sp + (png_size_t)row_width;
2774 for (i = 0; i < row_width; i++)
2775 {
2776 *(--dp) = *(--sp);
2777 *(--dp) = *(--sp);
2778 *(--dp) = *(--sp);
2779 *(--dp) = lo_filler;
2780 }
2781 row_info->channels = 4;
2782 row_info->pixel_depth = 32;
2783 row_info->rowbytes = row_width * 4;
2784 }
2785 }
2786
2787 #ifdef PNG_READ_16BIT_SUPPORTED
2788 else if (row_info->bit_depth == 16)
2789 {
2790 if (flags & PNG_FLAG_FILLER_AFTER)
2791 {
2792 /* This changes the data from RRGGBB to RRGGBBXX */
2793 png_bytep sp = row + (png_size_t)row_width * 6;
2794 png_bytep dp = sp + (png_size_t)row_width * 2;
2795 for (i = 1; i < row_width; i++)
2796 {
2797 *(--dp) = hi_filler;
2798 *(--dp) = lo_filler;
2799 *(--dp) = *(--sp);
2800 *(--dp) = *(--sp);
2801 *(--dp) = *(--sp);
2802 *(--dp) = *(--sp);
2803 *(--dp) = *(--sp);
2804 *(--dp) = *(--sp);
2805 }
2806 *(--dp) = hi_filler;
2807 *(--dp) = lo_filler;
2808 row_info->channels = 4;
2809 row_info->pixel_depth = 64;
2810 row_info->rowbytes = row_width * 8;
2811 }
2812
2813 else
2814 {
2815 /* This changes the data from RRGGBB to XXRRGGBB */
2816 png_bytep sp = row + (png_size_t)row_width * 6;
2817 png_bytep dp = sp + (png_size_t)row_width * 2;
2818 for (i = 0; i < row_width; i++)
2819 {
2820 *(--dp) = *(--sp);
2821 *(--dp) = *(--sp);
2822 *(--dp) = *(--sp);
2823 *(--dp) = *(--sp);
2824 *(--dp) = *(--sp);
2825 *(--dp) = *(--sp);
2826 *(--dp) = hi_filler;
2827 *(--dp) = lo_filler;
2828 }
2829
2830 row_info->channels = 4;
2831 row_info->pixel_depth = 64;
2832 row_info->rowbytes = row_width * 8;
2833 }
2834 }
2835 #endif
2836 } /* COLOR_TYPE == RGB */
2837 }
2838 #endif
2839
2840 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2841 /* Expand grayscale files to RGB, with or without alpha */
2842 static void
png_do_gray_to_rgb(png_row_infop row_info,png_bytep row)2843 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
2844 {
2845 png_uint_32 i;
2846 png_uint_32 row_width = row_info->width;
2847
2848 png_debug(1, "in png_do_gray_to_rgb");
2849
2850 if (row_info->bit_depth >= 8 &&
2851 !(row_info->color_type & PNG_COLOR_MASK_COLOR))
2852 {
2853 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
2854 {
2855 if (row_info->bit_depth == 8)
2856 {
2857 /* This changes G to RGB */
2858 png_bytep sp = row + (png_size_t)row_width - 1;
2859 png_bytep dp = sp + (png_size_t)row_width * 2;
2860 for (i = 0; i < row_width; i++)
2861 {
2862 *(dp--) = *sp;
2863 *(dp--) = *sp;
2864 *(dp--) = *(sp--);
2865 }
2866 }
2867
2868 else
2869 {
2870 /* This changes GG to RRGGBB */
2871 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2872 png_bytep dp = sp + (png_size_t)row_width * 4;
2873 for (i = 0; i < row_width; i++)
2874 {
2875 *(dp--) = *sp;
2876 *(dp--) = *(sp - 1);
2877 *(dp--) = *sp;
2878 *(dp--) = *(sp - 1);
2879 *(dp--) = *(sp--);
2880 *(dp--) = *(sp--);
2881 }
2882 }
2883 }
2884
2885 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2886 {
2887 if (row_info->bit_depth == 8)
2888 {
2889 /* This changes GA to RGBA */
2890 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2891 png_bytep dp = sp + (png_size_t)row_width * 2;
2892 for (i = 0; i < row_width; i++)
2893 {
2894 *(dp--) = *(sp--);
2895 *(dp--) = *sp;
2896 *(dp--) = *sp;
2897 *(dp--) = *(sp--);
2898 }
2899 }
2900
2901 else
2902 {
2903 /* This changes GGAA to RRGGBBAA */
2904 png_bytep sp = row + (png_size_t)row_width * 4 - 1;
2905 png_bytep dp = sp + (png_size_t)row_width * 4;
2906 for (i = 0; i < row_width; i++)
2907 {
2908 *(dp--) = *(sp--);
2909 *(dp--) = *(sp--);
2910 *(dp--) = *sp;
2911 *(dp--) = *(sp - 1);
2912 *(dp--) = *sp;
2913 *(dp--) = *(sp - 1);
2914 *(dp--) = *(sp--);
2915 *(dp--) = *(sp--);
2916 }
2917 }
2918 }
2919 row_info->channels = (png_byte)(row_info->channels + 2);
2920 row_info->color_type |= PNG_COLOR_MASK_COLOR;
2921 row_info->pixel_depth = (png_byte)(row_info->channels *
2922 row_info->bit_depth);
2923 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
2924 }
2925 }
2926 #endif
2927
2928 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2929 /* Reduce RGB files to grayscale, with or without alpha
2930 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
2931 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
2932 * versions dated 1998 through November 2002 have been archived at
2933 * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
2934 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
2935 * Charles Poynton poynton at poynton.com
2936 *
2937 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
2938 *
2939 * which can be expressed with integers as
2940 *
2941 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
2942 *
2943 * Poynton's current link (as of January 2003 through July 2011):
2944 * <http://www.poynton.com/notes/colour_and_gamma/>
2945 * has changed the numbers slightly:
2946 *
2947 * Y = 0.2126*R + 0.7152*G + 0.0722*B
2948 *
2949 * which can be expressed with integers as
2950 *
2951 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
2952 *
2953 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
2954 * end point chromaticities and the D65 white point. Depending on the
2955 * precision used for the D65 white point this produces a variety of different
2956 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
2957 * used (0.3127,0.3290) the Y calculation would be:
2958 *
2959 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
2960 *
2961 * While this is correct the rounding results in an overflow for white, because
2962 * the sum of the rounded coefficients is 32769, not 32768. Consequently
2963 * libpng uses, instead, the closest non-overflowing approximation:
2964 *
2965 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
2966 *
2967 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
2968 * (including an sRGB chunk) then the chromaticities are used to calculate the
2969 * coefficients. See the chunk handling in pngrutil.c for more information.
2970 *
2971 * In all cases the calculation is to be done in a linear colorspace. If no
2972 * gamma information is available to correct the encoding of the original RGB
2973 * values this results in an implicit assumption that the original PNG RGB
2974 * values were linear.
2975 *
2976 * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
2977 * the API takes just red and green coefficients the blue coefficient is
2978 * calculated to make the sum 32768. This will result in different rounding
2979 * to that used above.
2980 */
2981 static int
png_do_rgb_to_gray(png_structrp png_ptr,png_row_infop row_info,png_bytep row)2982 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
2983
2984 {
2985 int rgb_error = 0;
2986
2987 png_debug(1, "in png_do_rgb_to_gray");
2988
2989 if (!(row_info->color_type & PNG_COLOR_MASK_PALETTE) &&
2990 (row_info->color_type & PNG_COLOR_MASK_COLOR))
2991 {
2992 PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
2993 PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
2994 PNG_CONST png_uint_32 bc = 32768 - rc - gc;
2995 PNG_CONST png_uint_32 row_width = row_info->width;
2996 PNG_CONST int have_alpha =
2997 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
2998
2999 if (row_info->bit_depth == 8)
3000 {
3001 #ifdef PNG_READ_GAMMA_SUPPORTED
3002 /* Notice that gamma to/from 1 are not necessarily inverses (if
3003 * there is an overall gamma correction). Prior to 1.5.5 this code
3004 * checked the linearized values for equality; this doesn't match
3005 * the documentation, the original values must be checked.
3006 */
3007 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
3008 {
3009 png_bytep sp = row;
3010 png_bytep dp = row;
3011 png_uint_32 i;
3012
3013 for (i = 0; i < row_width; i++)
3014 {
3015 png_byte red = *(sp++);
3016 png_byte green = *(sp++);
3017 png_byte blue = *(sp++);
3018
3019 if (red != green || red != blue)
3020 {
3021 red = png_ptr->gamma_to_1[red];
3022 green = png_ptr->gamma_to_1[green];
3023 blue = png_ptr->gamma_to_1[blue];
3024
3025 rgb_error |= 1;
3026 *(dp++) = png_ptr->gamma_from_1[
3027 (rc*red + gc*green + bc*blue + 16384)>>15];
3028 }
3029
3030 else
3031 {
3032 /* If there is no overall correction the table will not be
3033 * set.
3034 */
3035 if (png_ptr->gamma_table != NULL)
3036 red = png_ptr->gamma_table[red];
3037
3038 *(dp++) = red;
3039 }
3040
3041 if (have_alpha)
3042 *(dp++) = *(sp++);
3043 }
3044 }
3045 else
3046 #endif
3047 {
3048 png_bytep sp = row;
3049 png_bytep dp = row;
3050 png_uint_32 i;
3051
3052 for (i = 0; i < row_width; i++)
3053 {
3054 png_byte red = *(sp++);
3055 png_byte green = *(sp++);
3056 png_byte blue = *(sp++);
3057
3058 if (red != green || red != blue)
3059 {
3060 rgb_error |= 1;
3061 /* NOTE: this is the historical approach which simply
3062 * truncates the results.
3063 */
3064 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
3065 }
3066
3067 else
3068 *(dp++) = red;
3069
3070 if (have_alpha)
3071 *(dp++) = *(sp++);
3072 }
3073 }
3074 }
3075
3076 else /* RGB bit_depth == 16 */
3077 {
3078 #ifdef PNG_READ_GAMMA_SUPPORTED
3079 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
3080 {
3081 png_bytep sp = row;
3082 png_bytep dp = row;
3083 png_uint_32 i;
3084
3085 for (i = 0; i < row_width; i++)
3086 {
3087 png_uint_16 red, green, blue, w;
3088
3089 red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3090 green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3091 blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3092
3093 if (red == green && red == blue)
3094 {
3095 if (png_ptr->gamma_16_table != NULL)
3096 w = png_ptr->gamma_16_table[(red&0xff)
3097 >> png_ptr->gamma_shift][red>>8];
3098
3099 else
3100 w = red;
3101 }
3102
3103 else
3104 {
3105 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff)
3106 >> png_ptr->gamma_shift][red>>8];
3107 png_uint_16 green_1 =
3108 png_ptr->gamma_16_to_1[(green&0xff) >>
3109 png_ptr->gamma_shift][green>>8];
3110 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff)
3111 >> png_ptr->gamma_shift][blue>>8];
3112 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
3113 + bc*blue_1 + 16384)>>15);
3114 w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
3115 png_ptr->gamma_shift][gray16 >> 8];
3116 rgb_error |= 1;
3117 }
3118
3119 *(dp++) = (png_byte)((w>>8) & 0xff);
3120 *(dp++) = (png_byte)(w & 0xff);
3121
3122 if (have_alpha)
3123 {
3124 *(dp++) = *(sp++);
3125 *(dp++) = *(sp++);
3126 }
3127 }
3128 }
3129 else
3130 #endif
3131 {
3132 png_bytep sp = row;
3133 png_bytep dp = row;
3134 png_uint_32 i;
3135
3136 for (i = 0; i < row_width; i++)
3137 {
3138 png_uint_16 red, green, blue, gray16;
3139
3140 red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3141 green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3142 blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3143
3144 if (red != green || red != blue)
3145 rgb_error |= 1;
3146
3147 /* From 1.5.5 in the 16 bit case do the accurate conversion even
3148 * in the 'fast' case - this is because this is where the code
3149 * ends up when handling linear 16 bit data.
3150 */
3151 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
3152 15);
3153 *(dp++) = (png_byte)((gray16>>8) & 0xff);
3154 *(dp++) = (png_byte)(gray16 & 0xff);
3155
3156 if (have_alpha)
3157 {
3158 *(dp++) = *(sp++);
3159 *(dp++) = *(sp++);
3160 }
3161 }
3162 }
3163 }
3164
3165 row_info->channels = (png_byte)(row_info->channels - 2);
3166 row_info->color_type = (png_byte)(row_info->color_type &
3167 ~PNG_COLOR_MASK_COLOR);
3168 row_info->pixel_depth = (png_byte)(row_info->channels *
3169 row_info->bit_depth);
3170 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3171 }
3172 return rgb_error;
3173 }
3174 #endif
3175
3176 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
3177 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
3178 /* Replace any alpha or transparency with the supplied background color.
3179 * "background" is already in the screen gamma, while "background_1" is
3180 * at a gamma of 1.0. Paletted files have already been taken care of.
3181 */
3182 static void
png_do_compose(png_row_infop row_info,png_bytep row,png_structrp png_ptr)3183 png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3184 {
3185 #ifdef PNG_READ_GAMMA_SUPPORTED
3186 png_const_bytep gamma_table = png_ptr->gamma_table;
3187 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
3188 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
3189 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
3190 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
3191 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
3192 int gamma_shift = png_ptr->gamma_shift;
3193 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
3194 #endif
3195
3196 png_bytep sp;
3197 png_uint_32 i;
3198 png_uint_32 row_width = row_info->width;
3199 int shift;
3200
3201 png_debug(1, "in png_do_compose");
3202
3203 {
3204 switch (row_info->color_type)
3205 {
3206 case PNG_COLOR_TYPE_GRAY:
3207 {
3208 switch (row_info->bit_depth)
3209 {
3210 case 1:
3211 {
3212 sp = row;
3213 shift = 7;
3214 for (i = 0; i < row_width; i++)
3215 {
3216 if ((png_uint_16)((*sp >> shift) & 0x01)
3217 == png_ptr->trans_color.gray)
3218 {
3219 unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
3220 tmp |= png_ptr->background.gray << shift;
3221 *sp = (png_byte)(tmp & 0xff);
3222 }
3223
3224 if (!shift)
3225 {
3226 shift = 7;
3227 sp++;
3228 }
3229
3230 else
3231 shift--;
3232 }
3233 break;
3234 }
3235
3236 case 2:
3237 {
3238 #ifdef PNG_READ_GAMMA_SUPPORTED
3239 if (gamma_table != NULL)
3240 {
3241 sp = row;
3242 shift = 6;
3243 for (i = 0; i < row_width; i++)
3244 {
3245 if ((png_uint_16)((*sp >> shift) & 0x03)
3246 == png_ptr->trans_color.gray)
3247 {
3248 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3249 tmp |= png_ptr->background.gray << shift;
3250 *sp = (png_byte)(tmp & 0xff);
3251 }
3252
3253 else
3254 {
3255 unsigned int p = (*sp >> shift) & 0x03;
3256 unsigned int g = (gamma_table [p | (p << 2) |
3257 (p << 4) | (p << 6)] >> 6) & 0x03;
3258 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3259 tmp |= g << shift;
3260 *sp = (png_byte)(tmp & 0xff);
3261 }
3262
3263 if (!shift)
3264 {
3265 shift = 6;
3266 sp++;
3267 }
3268
3269 else
3270 shift -= 2;
3271 }
3272 }
3273
3274 else
3275 #endif
3276 {
3277 sp = row;
3278 shift = 6;
3279 for (i = 0; i < row_width; i++)
3280 {
3281 if ((png_uint_16)((*sp >> shift) & 0x03)
3282 == png_ptr->trans_color.gray)
3283 {
3284 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3285 tmp |= png_ptr->background.gray << shift;
3286 *sp = (png_byte)(tmp & 0xff);
3287 }
3288
3289 if (!shift)
3290 {
3291 shift = 6;
3292 sp++;
3293 }
3294
3295 else
3296 shift -= 2;
3297 }
3298 }
3299 break;
3300 }
3301
3302 case 4:
3303 {
3304 #ifdef PNG_READ_GAMMA_SUPPORTED
3305 if (gamma_table != NULL)
3306 {
3307 sp = row;
3308 shift = 4;
3309 for (i = 0; i < row_width; i++)
3310 {
3311 if ((png_uint_16)((*sp >> shift) & 0x0f)
3312 == png_ptr->trans_color.gray)
3313 {
3314 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3315 tmp |= png_ptr->background.gray << shift;
3316 *sp = (png_byte)(tmp & 0xff);
3317 }
3318
3319 else
3320 {
3321 unsigned int p = (*sp >> shift) & 0x0f;
3322 unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
3323 0x0f;
3324 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3325 tmp |= g << shift;
3326 *sp = (png_byte)(tmp & 0xff);
3327 }
3328
3329 if (!shift)
3330 {
3331 shift = 4;
3332 sp++;
3333 }
3334
3335 else
3336 shift -= 4;
3337 }
3338 }
3339
3340 else
3341 #endif
3342 {
3343 sp = row;
3344 shift = 4;
3345 for (i = 0; i < row_width; i++)
3346 {
3347 if ((png_uint_16)((*sp >> shift) & 0x0f)
3348 == png_ptr->trans_color.gray)
3349 {
3350 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3351 tmp |= png_ptr->background.gray << shift;
3352 *sp = (png_byte)(tmp & 0xff);
3353 }
3354
3355 if (!shift)
3356 {
3357 shift = 4;
3358 sp++;
3359 }
3360
3361 else
3362 shift -= 4;
3363 }
3364 }
3365 break;
3366 }
3367
3368 case 8:
3369 {
3370 #ifdef PNG_READ_GAMMA_SUPPORTED
3371 if (gamma_table != NULL)
3372 {
3373 sp = row;
3374 for (i = 0; i < row_width; i++, sp++)
3375 {
3376 if (*sp == png_ptr->trans_color.gray)
3377 *sp = (png_byte)png_ptr->background.gray;
3378
3379 else
3380 *sp = gamma_table[*sp];
3381 }
3382 }
3383 else
3384 #endif
3385 {
3386 sp = row;
3387 for (i = 0; i < row_width; i++, sp++)
3388 {
3389 if (*sp == png_ptr->trans_color.gray)
3390 *sp = (png_byte)png_ptr->background.gray;
3391 }
3392 }
3393 break;
3394 }
3395
3396 case 16:
3397 {
3398 #ifdef PNG_READ_GAMMA_SUPPORTED
3399 if (gamma_16 != NULL)
3400 {
3401 sp = row;
3402 for (i = 0; i < row_width; i++, sp += 2)
3403 {
3404 png_uint_16 v;
3405
3406 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3407
3408 if (v == png_ptr->trans_color.gray)
3409 {
3410 /* Background is already in screen gamma */
3411 *sp = (png_byte)((png_ptr->background.gray >> 8)
3412 & 0xff);
3413 *(sp + 1) = (png_byte)(png_ptr->background.gray
3414 & 0xff);
3415 }
3416
3417 else
3418 {
3419 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3420 *sp = (png_byte)((v >> 8) & 0xff);
3421 *(sp + 1) = (png_byte)(v & 0xff);
3422 }
3423 }
3424 }
3425 else
3426 #endif
3427 {
3428 sp = row;
3429 for (i = 0; i < row_width; i++, sp += 2)
3430 {
3431 png_uint_16 v;
3432
3433 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3434
3435 if (v == png_ptr->trans_color.gray)
3436 {
3437 *sp = (png_byte)((png_ptr->background.gray >> 8)
3438 & 0xff);
3439 *(sp + 1) = (png_byte)(png_ptr->background.gray
3440 & 0xff);
3441 }
3442 }
3443 }
3444 break;
3445 }
3446
3447 default:
3448 break;
3449 }
3450 break;
3451 }
3452
3453 case PNG_COLOR_TYPE_RGB:
3454 {
3455 if (row_info->bit_depth == 8)
3456 {
3457 #ifdef PNG_READ_GAMMA_SUPPORTED
3458 if (gamma_table != NULL)
3459 {
3460 sp = row;
3461 for (i = 0; i < row_width; i++, sp += 3)
3462 {
3463 if (*sp == png_ptr->trans_color.red &&
3464 *(sp + 1) == png_ptr->trans_color.green &&
3465 *(sp + 2) == png_ptr->trans_color.blue)
3466 {
3467 *sp = (png_byte)png_ptr->background.red;
3468 *(sp + 1) = (png_byte)png_ptr->background.green;
3469 *(sp + 2) = (png_byte)png_ptr->background.blue;
3470 }
3471
3472 else
3473 {
3474 *sp = gamma_table[*sp];
3475 *(sp + 1) = gamma_table[*(sp + 1)];
3476 *(sp + 2) = gamma_table[*(sp + 2)];
3477 }
3478 }
3479 }
3480 else
3481 #endif
3482 {
3483 sp = row;
3484 for (i = 0; i < row_width; i++, sp += 3)
3485 {
3486 if (*sp == png_ptr->trans_color.red &&
3487 *(sp + 1) == png_ptr->trans_color.green &&
3488 *(sp + 2) == png_ptr->trans_color.blue)
3489 {
3490 *sp = (png_byte)png_ptr->background.red;
3491 *(sp + 1) = (png_byte)png_ptr->background.green;
3492 *(sp + 2) = (png_byte)png_ptr->background.blue;
3493 }
3494 }
3495 }
3496 }
3497 else /* if (row_info->bit_depth == 16) */
3498 {
3499 #ifdef PNG_READ_GAMMA_SUPPORTED
3500 if (gamma_16 != NULL)
3501 {
3502 sp = row;
3503 for (i = 0; i < row_width; i++, sp += 6)
3504 {
3505 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3506
3507 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3508 + *(sp + 3));
3509
3510 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3511 + *(sp + 5));
3512
3513 if (r == png_ptr->trans_color.red &&
3514 g == png_ptr->trans_color.green &&
3515 b == png_ptr->trans_color.blue)
3516 {
3517 /* Background is already in screen gamma */
3518 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3519 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3520 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3521 & 0xff);
3522 *(sp + 3) = (png_byte)(png_ptr->background.green
3523 & 0xff);
3524 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3525 & 0xff);
3526 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3527 }
3528
3529 else
3530 {
3531 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3532 *sp = (png_byte)((v >> 8) & 0xff);
3533 *(sp + 1) = (png_byte)(v & 0xff);
3534
3535 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3536 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3537 *(sp + 3) = (png_byte)(v & 0xff);
3538
3539 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3540 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3541 *(sp + 5) = (png_byte)(v & 0xff);
3542 }
3543 }
3544 }
3545
3546 else
3547 #endif
3548 {
3549 sp = row;
3550 for (i = 0; i < row_width; i++, sp += 6)
3551 {
3552 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3553
3554 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3555 + *(sp + 3));
3556
3557 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3558 + *(sp + 5));
3559
3560 if (r == png_ptr->trans_color.red &&
3561 g == png_ptr->trans_color.green &&
3562 b == png_ptr->trans_color.blue)
3563 {
3564 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3565 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3566 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3567 & 0xff);
3568 *(sp + 3) = (png_byte)(png_ptr->background.green
3569 & 0xff);
3570 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3571 & 0xff);
3572 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3573 }
3574 }
3575 }
3576 }
3577 break;
3578 }
3579
3580 case PNG_COLOR_TYPE_GRAY_ALPHA:
3581 {
3582 if (row_info->bit_depth == 8)
3583 {
3584 #ifdef PNG_READ_GAMMA_SUPPORTED
3585 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3586 gamma_table != NULL)
3587 {
3588 sp = row;
3589 for (i = 0; i < row_width; i++, sp += 2)
3590 {
3591 png_uint_16 a = *(sp + 1);
3592
3593 if (a == 0xff)
3594 *sp = gamma_table[*sp];
3595
3596 else if (a == 0)
3597 {
3598 /* Background is already in screen gamma */
3599 *sp = (png_byte)png_ptr->background.gray;
3600 }
3601
3602 else
3603 {
3604 png_byte v, w;
3605
3606 v = gamma_to_1[*sp];
3607 png_composite(w, v, a, png_ptr->background_1.gray);
3608 if (!optimize)
3609 w = gamma_from_1[w];
3610 *sp = w;
3611 }
3612 }
3613 }
3614 else
3615 #endif
3616 {
3617 sp = row;
3618 for (i = 0; i < row_width; i++, sp += 2)
3619 {
3620 png_byte a = *(sp + 1);
3621
3622 if (a == 0)
3623 *sp = (png_byte)png_ptr->background.gray;
3624
3625 else if (a < 0xff)
3626 png_composite(*sp, *sp, a, png_ptr->background.gray);
3627 }
3628 }
3629 }
3630 else /* if (png_ptr->bit_depth == 16) */
3631 {
3632 #ifdef PNG_READ_GAMMA_SUPPORTED
3633 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3634 gamma_16_to_1 != NULL)
3635 {
3636 sp = row;
3637 for (i = 0; i < row_width; i++, sp += 4)
3638 {
3639 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3640 + *(sp + 3));
3641
3642 if (a == (png_uint_16)0xffff)
3643 {
3644 png_uint_16 v;
3645
3646 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3647 *sp = (png_byte)((v >> 8) & 0xff);
3648 *(sp + 1) = (png_byte)(v & 0xff);
3649 }
3650
3651 else if (a == 0)
3652 {
3653 /* Background is already in screen gamma */
3654 *sp = (png_byte)((png_ptr->background.gray >> 8)
3655 & 0xff);
3656 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3657 }
3658
3659 else
3660 {
3661 png_uint_16 g, v, w;
3662
3663 g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3664 png_composite_16(v, g, a, png_ptr->background_1.gray);
3665 if (optimize)
3666 w = v;
3667 else
3668 w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8];
3669 *sp = (png_byte)((w >> 8) & 0xff);
3670 *(sp + 1) = (png_byte)(w & 0xff);
3671 }
3672 }
3673 }
3674 else
3675 #endif
3676 {
3677 sp = row;
3678 for (i = 0; i < row_width; i++, sp += 4)
3679 {
3680 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3681 + *(sp + 3));
3682
3683 if (a == 0)
3684 {
3685 *sp = (png_byte)((png_ptr->background.gray >> 8)
3686 & 0xff);
3687 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3688 }
3689
3690 else if (a < 0xffff)
3691 {
3692 png_uint_16 g, v;
3693
3694 g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3695 png_composite_16(v, g, a, png_ptr->background.gray);
3696 *sp = (png_byte)((v >> 8) & 0xff);
3697 *(sp + 1) = (png_byte)(v & 0xff);
3698 }
3699 }
3700 }
3701 }
3702 break;
3703 }
3704
3705 case PNG_COLOR_TYPE_RGB_ALPHA:
3706 {
3707 if (row_info->bit_depth == 8)
3708 {
3709 #ifdef PNG_READ_GAMMA_SUPPORTED
3710 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3711 gamma_table != NULL)
3712 {
3713 sp = row;
3714 for (i = 0; i < row_width; i++, sp += 4)
3715 {
3716 png_byte a = *(sp + 3);
3717
3718 if (a == 0xff)
3719 {
3720 *sp = gamma_table[*sp];
3721 *(sp + 1) = gamma_table[*(sp + 1)];
3722 *(sp + 2) = gamma_table[*(sp + 2)];
3723 }
3724
3725 else if (a == 0)
3726 {
3727 /* Background is already in screen gamma */
3728 *sp = (png_byte)png_ptr->background.red;
3729 *(sp + 1) = (png_byte)png_ptr->background.green;
3730 *(sp + 2) = (png_byte)png_ptr->background.blue;
3731 }
3732
3733 else
3734 {
3735 png_byte v, w;
3736
3737 v = gamma_to_1[*sp];
3738 png_composite(w, v, a, png_ptr->background_1.red);
3739 if (!optimize) w = gamma_from_1[w];
3740 *sp = w;
3741
3742 v = gamma_to_1[*(sp + 1)];
3743 png_composite(w, v, a, png_ptr->background_1.green);
3744 if (!optimize) w = gamma_from_1[w];
3745 *(sp + 1) = w;
3746
3747 v = gamma_to_1[*(sp + 2)];
3748 png_composite(w, v, a, png_ptr->background_1.blue);
3749 if (!optimize) w = gamma_from_1[w];
3750 *(sp + 2) = w;
3751 }
3752 }
3753 }
3754 else
3755 #endif
3756 {
3757 sp = row;
3758 for (i = 0; i < row_width; i++, sp += 4)
3759 {
3760 png_byte a = *(sp + 3);
3761
3762 if (a == 0)
3763 {
3764 *sp = (png_byte)png_ptr->background.red;
3765 *(sp + 1) = (png_byte)png_ptr->background.green;
3766 *(sp + 2) = (png_byte)png_ptr->background.blue;
3767 }
3768
3769 else if (a < 0xff)
3770 {
3771 png_composite(*sp, *sp, a, png_ptr->background.red);
3772
3773 png_composite(*(sp + 1), *(sp + 1), a,
3774 png_ptr->background.green);
3775
3776 png_composite(*(sp + 2), *(sp + 2), a,
3777 png_ptr->background.blue);
3778 }
3779 }
3780 }
3781 }
3782 else /* if (row_info->bit_depth == 16) */
3783 {
3784 #ifdef PNG_READ_GAMMA_SUPPORTED
3785 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3786 gamma_16_to_1 != NULL)
3787 {
3788 sp = row;
3789 for (i = 0; i < row_width; i++, sp += 8)
3790 {
3791 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3792 << 8) + (png_uint_16)(*(sp + 7)));
3793
3794 if (a == (png_uint_16)0xffff)
3795 {
3796 png_uint_16 v;
3797
3798 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3799 *sp = (png_byte)((v >> 8) & 0xff);
3800 *(sp + 1) = (png_byte)(v & 0xff);
3801
3802 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3803 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3804 *(sp + 3) = (png_byte)(v & 0xff);
3805
3806 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3807 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3808 *(sp + 5) = (png_byte)(v & 0xff);
3809 }
3810
3811 else if (a == 0)
3812 {
3813 /* Background is already in screen gamma */
3814 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3815 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3816 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3817 & 0xff);
3818 *(sp + 3) = (png_byte)(png_ptr->background.green
3819 & 0xff);
3820 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3821 & 0xff);
3822 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3823 }
3824
3825 else
3826 {
3827 png_uint_16 v, w;
3828
3829 v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3830 png_composite_16(w, v, a, png_ptr->background_1.red);
3831 if (!optimize)
3832 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
3833 8];
3834 *sp = (png_byte)((w >> 8) & 0xff);
3835 *(sp + 1) = (png_byte)(w & 0xff);
3836
3837 v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
3838 png_composite_16(w, v, a, png_ptr->background_1.green);
3839 if (!optimize)
3840 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
3841 8];
3842
3843 *(sp + 2) = (png_byte)((w >> 8) & 0xff);
3844 *(sp + 3) = (png_byte)(w & 0xff);
3845
3846 v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
3847 png_composite_16(w, v, a, png_ptr->background_1.blue);
3848 if (!optimize)
3849 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
3850 8];
3851
3852 *(sp + 4) = (png_byte)((w >> 8) & 0xff);
3853 *(sp + 5) = (png_byte)(w & 0xff);
3854 }
3855 }
3856 }
3857
3858 else
3859 #endif
3860 {
3861 sp = row;
3862 for (i = 0; i < row_width; i++, sp += 8)
3863 {
3864 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3865 << 8) + (png_uint_16)(*(sp + 7)));
3866
3867 if (a == 0)
3868 {
3869 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3870 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3871 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3872 & 0xff);
3873 *(sp + 3) = (png_byte)(png_ptr->background.green
3874 & 0xff);
3875 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3876 & 0xff);
3877 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3878 }
3879
3880 else if (a < 0xffff)
3881 {
3882 png_uint_16 v;
3883
3884 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3885 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3886 + *(sp + 3));
3887 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3888 + *(sp + 5));
3889
3890 png_composite_16(v, r, a, png_ptr->background.red);
3891 *sp = (png_byte)((v >> 8) & 0xff);
3892 *(sp + 1) = (png_byte)(v & 0xff);
3893
3894 png_composite_16(v, g, a, png_ptr->background.green);
3895 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3896 *(sp + 3) = (png_byte)(v & 0xff);
3897
3898 png_composite_16(v, b, a, png_ptr->background.blue);
3899 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3900 *(sp + 5) = (png_byte)(v & 0xff);
3901 }
3902 }
3903 }
3904 }
3905 break;
3906 }
3907
3908 default:
3909 break;
3910 }
3911 }
3912 }
3913 #endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_READ_ALPHA_MODE_SUPPORTED */
3914
3915 #ifdef PNG_READ_GAMMA_SUPPORTED
3916 /* Gamma correct the image, avoiding the alpha channel. Make sure
3917 * you do this after you deal with the transparency issue on grayscale
3918 * or RGB images. If your bit depth is 8, use gamma_table, if it
3919 * is 16, use gamma_16_table and gamma_shift. Build these with
3920 * build_gamma_table().
3921 */
3922 static void
png_do_gamma(png_row_infop row_info,png_bytep row,png_structrp png_ptr)3923 png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3924 {
3925 png_const_bytep gamma_table = png_ptr->gamma_table;
3926 png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
3927 int gamma_shift = png_ptr->gamma_shift;
3928
3929 png_bytep sp;
3930 png_uint_32 i;
3931 png_uint_32 row_width=row_info->width;
3932
3933 png_debug(1, "in png_do_gamma");
3934
3935 if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
3936 (row_info->bit_depth == 16 && gamma_16_table != NULL)))
3937 {
3938 switch (row_info->color_type)
3939 {
3940 case PNG_COLOR_TYPE_RGB:
3941 {
3942 if (row_info->bit_depth == 8)
3943 {
3944 sp = row;
3945 for (i = 0; i < row_width; i++)
3946 {
3947 *sp = gamma_table[*sp];
3948 sp++;
3949 *sp = gamma_table[*sp];
3950 sp++;
3951 *sp = gamma_table[*sp];
3952 sp++;
3953 }
3954 }
3955
3956 else /* if (row_info->bit_depth == 16) */
3957 {
3958 sp = row;
3959 for (i = 0; i < row_width; i++)
3960 {
3961 png_uint_16 v;
3962
3963 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
3964 *sp = (png_byte)((v >> 8) & 0xff);
3965 *(sp + 1) = (png_byte)(v & 0xff);
3966 sp += 2;
3967
3968 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
3969 *sp = (png_byte)((v >> 8) & 0xff);
3970 *(sp + 1) = (png_byte)(v & 0xff);
3971 sp += 2;
3972
3973 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
3974 *sp = (png_byte)((v >> 8) & 0xff);
3975 *(sp + 1) = (png_byte)(v & 0xff);
3976 sp += 2;
3977 }
3978 }
3979 break;
3980 }
3981
3982 case PNG_COLOR_TYPE_RGB_ALPHA:
3983 {
3984 if (row_info->bit_depth == 8)
3985 {
3986 sp = row;
3987 for (i = 0; i < row_width; i++)
3988 {
3989 *sp = gamma_table[*sp];
3990 sp++;
3991
3992 *sp = gamma_table[*sp];
3993 sp++;
3994
3995 *sp = gamma_table[*sp];
3996 sp++;
3997
3998 sp++;
3999 }
4000 }
4001
4002 else /* if (row_info->bit_depth == 16) */
4003 {
4004 sp = row;
4005 for (i = 0; i < row_width; i++)
4006 {
4007 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4008 *sp = (png_byte)((v >> 8) & 0xff);
4009 *(sp + 1) = (png_byte)(v & 0xff);
4010 sp += 2;
4011
4012 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4013 *sp = (png_byte)((v >> 8) & 0xff);
4014 *(sp + 1) = (png_byte)(v & 0xff);
4015 sp += 2;
4016
4017 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4018 *sp = (png_byte)((v >> 8) & 0xff);
4019 *(sp + 1) = (png_byte)(v & 0xff);
4020 sp += 4;
4021 }
4022 }
4023 break;
4024 }
4025
4026 case PNG_COLOR_TYPE_GRAY_ALPHA:
4027 {
4028 if (row_info->bit_depth == 8)
4029 {
4030 sp = row;
4031 for (i = 0; i < row_width; i++)
4032 {
4033 *sp = gamma_table[*sp];
4034 sp += 2;
4035 }
4036 }
4037
4038 else /* if (row_info->bit_depth == 16) */
4039 {
4040 sp = row;
4041 for (i = 0; i < row_width; i++)
4042 {
4043 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4044 *sp = (png_byte)((v >> 8) & 0xff);
4045 *(sp + 1) = (png_byte)(v & 0xff);
4046 sp += 4;
4047 }
4048 }
4049 break;
4050 }
4051
4052 case PNG_COLOR_TYPE_GRAY:
4053 {
4054 if (row_info->bit_depth == 2)
4055 {
4056 sp = row;
4057 for (i = 0; i < row_width; i += 4)
4058 {
4059 int a = *sp & 0xc0;
4060 int b = *sp & 0x30;
4061 int c = *sp & 0x0c;
4062 int d = *sp & 0x03;
4063
4064 *sp = (png_byte)(
4065 ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)|
4066 ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
4067 ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
4068 ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
4069 sp++;
4070 }
4071 }
4072
4073 if (row_info->bit_depth == 4)
4074 {
4075 sp = row;
4076 for (i = 0; i < row_width; i += 2)
4077 {
4078 int msb = *sp & 0xf0;
4079 int lsb = *sp & 0x0f;
4080
4081 *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
4082 | (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
4083 sp++;
4084 }
4085 }
4086
4087 else if (row_info->bit_depth == 8)
4088 {
4089 sp = row;
4090 for (i = 0; i < row_width; i++)
4091 {
4092 *sp = gamma_table[*sp];
4093 sp++;
4094 }
4095 }
4096
4097 else if (row_info->bit_depth == 16)
4098 {
4099 sp = row;
4100 for (i = 0; i < row_width; i++)
4101 {
4102 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4103 *sp = (png_byte)((v >> 8) & 0xff);
4104 *(sp + 1) = (png_byte)(v & 0xff);
4105 sp += 2;
4106 }
4107 }
4108 break;
4109 }
4110
4111 default:
4112 break;
4113 }
4114 }
4115 }
4116 #endif
4117
4118 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4119 /* Encode the alpha channel to the output gamma (the input channel is always
4120 * linear.) Called only with color types that have an alpha channel. Needs the
4121 * from_1 tables.
4122 */
4123 static void
png_do_encode_alpha(png_row_infop row_info,png_bytep row,png_structrp png_ptr)4124 png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
4125 {
4126 png_uint_32 row_width = row_info->width;
4127
4128 png_debug(1, "in png_do_encode_alpha");
4129
4130 if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
4131 {
4132 if (row_info->bit_depth == 8)
4133 {
4134 PNG_CONST png_bytep table = png_ptr->gamma_from_1;
4135
4136 if (table != NULL)
4137 {
4138 PNG_CONST int step =
4139 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
4140
4141 /* The alpha channel is the last component: */
4142 row += step - 1;
4143
4144 for (; row_width > 0; --row_width, row += step)
4145 *row = table[*row];
4146
4147 return;
4148 }
4149 }
4150
4151 else if (row_info->bit_depth == 16)
4152 {
4153 PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1;
4154 PNG_CONST int gamma_shift = png_ptr->gamma_shift;
4155
4156 if (table != NULL)
4157 {
4158 PNG_CONST int step =
4159 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
4160
4161 /* The alpha channel is the last component: */
4162 row += step - 2;
4163
4164 for (; row_width > 0; --row_width, row += step)
4165 {
4166 png_uint_16 v;
4167
4168 v = table[*(row + 1) >> gamma_shift][*row];
4169 *row = (png_byte)((v >> 8) & 0xff);
4170 *(row + 1) = (png_byte)(v & 0xff);
4171 }
4172
4173 return;
4174 }
4175 }
4176 }
4177
4178 /* Only get to here if called with a weird row_info; no harm has been done,
4179 * so just issue a warning.
4180 */
4181 png_warning(png_ptr, "png_do_encode_alpha: unexpected call");
4182 }
4183 #endif
4184
4185 #ifdef PNG_READ_EXPAND_SUPPORTED
4186 /* Expands a palette row to an RGB or RGBA row depending
4187 * upon whether you supply trans and num_trans.
4188 */
4189 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)4190 png_do_expand_palette(png_row_infop row_info, png_bytep row,
4191 png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
4192 {
4193 int shift, value;
4194 png_bytep sp, dp;
4195 png_uint_32 i;
4196 png_uint_32 row_width=row_info->width;
4197
4198 png_debug(1, "in png_do_expand_palette");
4199
4200 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4201 {
4202 if (row_info->bit_depth < 8)
4203 {
4204 switch (row_info->bit_depth)
4205 {
4206 case 1:
4207 {
4208 sp = row + (png_size_t)((row_width - 1) >> 3);
4209 dp = row + (png_size_t)row_width - 1;
4210 shift = 7 - (int)((row_width + 7) & 0x07);
4211 for (i = 0; i < row_width; i++)
4212 {
4213 if ((*sp >> shift) & 0x01)
4214 *dp = 1;
4215
4216 else
4217 *dp = 0;
4218
4219 if (shift == 7)
4220 {
4221 shift = 0;
4222 sp--;
4223 }
4224
4225 else
4226 shift++;
4227
4228 dp--;
4229 }
4230 break;
4231 }
4232
4233 case 2:
4234 {
4235 sp = row + (png_size_t)((row_width - 1) >> 2);
4236 dp = row + (png_size_t)row_width - 1;
4237 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4238 for (i = 0; i < row_width; i++)
4239 {
4240 value = (*sp >> shift) & 0x03;
4241 *dp = (png_byte)value;
4242 if (shift == 6)
4243 {
4244 shift = 0;
4245 sp--;
4246 }
4247
4248 else
4249 shift += 2;
4250
4251 dp--;
4252 }
4253 break;
4254 }
4255
4256 case 4:
4257 {
4258 sp = row + (png_size_t)((row_width - 1) >> 1);
4259 dp = row + (png_size_t)row_width - 1;
4260 shift = (int)((row_width & 0x01) << 2);
4261 for (i = 0; i < row_width; i++)
4262 {
4263 value = (*sp >> shift) & 0x0f;
4264 *dp = (png_byte)value;
4265 if (shift == 4)
4266 {
4267 shift = 0;
4268 sp--;
4269 }
4270
4271 else
4272 shift += 4;
4273
4274 dp--;
4275 }
4276 break;
4277 }
4278
4279 default:
4280 break;
4281 }
4282 row_info->bit_depth = 8;
4283 row_info->pixel_depth = 8;
4284 row_info->rowbytes = row_width;
4285 }
4286
4287 if (row_info->bit_depth == 8)
4288 {
4289 {
4290 if (num_trans > 0)
4291 {
4292 sp = row + (png_size_t)row_width - 1;
4293 dp = row + (png_size_t)(row_width << 2) - 1;
4294
4295 for (i = 0; i < row_width; i++)
4296 {
4297 if ((int)(*sp) >= num_trans)
4298 *dp-- = 0xff;
4299
4300 else
4301 *dp-- = trans_alpha[*sp];
4302
4303 *dp-- = palette[*sp].blue;
4304 *dp-- = palette[*sp].green;
4305 *dp-- = palette[*sp].red;
4306 sp--;
4307 }
4308 row_info->bit_depth = 8;
4309 row_info->pixel_depth = 32;
4310 row_info->rowbytes = row_width * 4;
4311 row_info->color_type = 6;
4312 row_info->channels = 4;
4313 }
4314
4315 else
4316 {
4317 sp = row + (png_size_t)row_width - 1;
4318 dp = row + (png_size_t)(row_width * 3) - 1;
4319
4320 for (i = 0; i < row_width; i++)
4321 {
4322 *dp-- = palette[*sp].blue;
4323 *dp-- = palette[*sp].green;
4324 *dp-- = palette[*sp].red;
4325 sp--;
4326 }
4327
4328 row_info->bit_depth = 8;
4329 row_info->pixel_depth = 24;
4330 row_info->rowbytes = row_width * 3;
4331 row_info->color_type = 2;
4332 row_info->channels = 3;
4333 }
4334 }
4335 }
4336 }
4337 }
4338
4339 /* If the bit depth < 8, it is expanded to 8. Also, if the already
4340 * expanded transparency value is supplied, an alpha channel is built.
4341 */
4342 static void
png_do_expand(png_row_infop row_info,png_bytep row,png_const_color_16p trans_color)4343 png_do_expand(png_row_infop row_info, png_bytep row,
4344 png_const_color_16p trans_color)
4345 {
4346 int shift, value;
4347 png_bytep sp, dp;
4348 png_uint_32 i;
4349 png_uint_32 row_width=row_info->width;
4350
4351 png_debug(1, "in png_do_expand");
4352
4353 {
4354 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
4355 {
4356 unsigned int gray = trans_color ? trans_color->gray : 0;
4357
4358 if (row_info->bit_depth < 8)
4359 {
4360 switch (row_info->bit_depth)
4361 {
4362 case 1:
4363 {
4364 gray = (gray & 0x01) * 0xff;
4365 sp = row + (png_size_t)((row_width - 1) >> 3);
4366 dp = row + (png_size_t)row_width - 1;
4367 shift = 7 - (int)((row_width + 7) & 0x07);
4368 for (i = 0; i < row_width; i++)
4369 {
4370 if ((*sp >> shift) & 0x01)
4371 *dp = 0xff;
4372
4373 else
4374 *dp = 0;
4375
4376 if (shift == 7)
4377 {
4378 shift = 0;
4379 sp--;
4380 }
4381
4382 else
4383 shift++;
4384
4385 dp--;
4386 }
4387 break;
4388 }
4389
4390 case 2:
4391 {
4392 gray = (gray & 0x03) * 0x55;
4393 sp = row + (png_size_t)((row_width - 1) >> 2);
4394 dp = row + (png_size_t)row_width - 1;
4395 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4396 for (i = 0; i < row_width; i++)
4397 {
4398 value = (*sp >> shift) & 0x03;
4399 *dp = (png_byte)(value | (value << 2) | (value << 4) |
4400 (value << 6));
4401 if (shift == 6)
4402 {
4403 shift = 0;
4404 sp--;
4405 }
4406
4407 else
4408 shift += 2;
4409
4410 dp--;
4411 }
4412 break;
4413 }
4414
4415 case 4:
4416 {
4417 gray = (gray & 0x0f) * 0x11;
4418 sp = row + (png_size_t)((row_width - 1) >> 1);
4419 dp = row + (png_size_t)row_width - 1;
4420 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
4421 for (i = 0; i < row_width; i++)
4422 {
4423 value = (*sp >> shift) & 0x0f;
4424 *dp = (png_byte)(value | (value << 4));
4425 if (shift == 4)
4426 {
4427 shift = 0;
4428 sp--;
4429 }
4430
4431 else
4432 shift = 4;
4433
4434 dp--;
4435 }
4436 break;
4437 }
4438
4439 default:
4440 break;
4441 }
4442
4443 row_info->bit_depth = 8;
4444 row_info->pixel_depth = 8;
4445 row_info->rowbytes = row_width;
4446 }
4447
4448 if (trans_color != NULL)
4449 {
4450 if (row_info->bit_depth == 8)
4451 {
4452 gray = gray & 0xff;
4453 sp = row + (png_size_t)row_width - 1;
4454 dp = row + (png_size_t)(row_width << 1) - 1;
4455
4456 for (i = 0; i < row_width; i++)
4457 {
4458 if (*sp == gray)
4459 *dp-- = 0;
4460
4461 else
4462 *dp-- = 0xff;
4463
4464 *dp-- = *sp--;
4465 }
4466 }
4467
4468 else if (row_info->bit_depth == 16)
4469 {
4470 unsigned int gray_high = (gray >> 8) & 0xff;
4471 unsigned int gray_low = gray & 0xff;
4472 sp = row + row_info->rowbytes - 1;
4473 dp = row + (row_info->rowbytes << 1) - 1;
4474 for (i = 0; i < row_width; i++)
4475 {
4476 if (*(sp - 1) == gray_high && *(sp) == gray_low)
4477 {
4478 *dp-- = 0;
4479 *dp-- = 0;
4480 }
4481
4482 else
4483 {
4484 *dp-- = 0xff;
4485 *dp-- = 0xff;
4486 }
4487
4488 *dp-- = *sp--;
4489 *dp-- = *sp--;
4490 }
4491 }
4492
4493 row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
4494 row_info->channels = 2;
4495 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
4496 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
4497 row_width);
4498 }
4499 }
4500 else if (row_info->color_type == PNG_COLOR_TYPE_RGB && trans_color)
4501 {
4502 if (row_info->bit_depth == 8)
4503 {
4504 png_byte red = (png_byte)(trans_color->red & 0xff);
4505 png_byte green = (png_byte)(trans_color->green & 0xff);
4506 png_byte blue = (png_byte)(trans_color->blue & 0xff);
4507 sp = row + (png_size_t)row_info->rowbytes - 1;
4508 dp = row + (png_size_t)(row_width << 2) - 1;
4509 for (i = 0; i < row_width; i++)
4510 {
4511 if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
4512 *dp-- = 0;
4513
4514 else
4515 *dp-- = 0xff;
4516
4517 *dp-- = *sp--;
4518 *dp-- = *sp--;
4519 *dp-- = *sp--;
4520 }
4521 }
4522 else if (row_info->bit_depth == 16)
4523 {
4524 png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff);
4525 png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff);
4526 png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff);
4527 png_byte red_low = (png_byte)(trans_color->red & 0xff);
4528 png_byte green_low = (png_byte)(trans_color->green & 0xff);
4529 png_byte blue_low = (png_byte)(trans_color->blue & 0xff);
4530 sp = row + row_info->rowbytes - 1;
4531 dp = row + (png_size_t)(row_width << 3) - 1;
4532 for (i = 0; i < row_width; i++)
4533 {
4534 if (*(sp - 5) == red_high &&
4535 *(sp - 4) == red_low &&
4536 *(sp - 3) == green_high &&
4537 *(sp - 2) == green_low &&
4538 *(sp - 1) == blue_high &&
4539 *(sp ) == blue_low)
4540 {
4541 *dp-- = 0;
4542 *dp-- = 0;
4543 }
4544
4545 else
4546 {
4547 *dp-- = 0xff;
4548 *dp-- = 0xff;
4549 }
4550
4551 *dp-- = *sp--;
4552 *dp-- = *sp--;
4553 *dp-- = *sp--;
4554 *dp-- = *sp--;
4555 *dp-- = *sp--;
4556 *dp-- = *sp--;
4557 }
4558 }
4559 row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
4560 row_info->channels = 4;
4561 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
4562 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4563 }
4564 }
4565 }
4566 #endif
4567
4568 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4569 /* If the bit depth is 8 and the color type is not a palette type expand the
4570 * whole row to 16 bits. Has no effect otherwise.
4571 */
4572 static void
png_do_expand_16(png_row_infop row_info,png_bytep row)4573 png_do_expand_16(png_row_infop row_info, png_bytep row)
4574 {
4575 if (row_info->bit_depth == 8 &&
4576 row_info->color_type != PNG_COLOR_TYPE_PALETTE)
4577 {
4578 /* The row have a sequence of bytes containing [0..255] and we need
4579 * to turn it into another row containing [0..65535], to do this we
4580 * calculate:
4581 *
4582 * (input / 255) * 65535
4583 *
4584 * Which happens to be exactly input * 257 and this can be achieved
4585 * simply by byte replication in place (copying backwards).
4586 */
4587 png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */
4588 png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */
4589 while (dp > sp)
4590 dp[-2] = dp[-1] = *--sp, dp -= 2;
4591
4592 row_info->rowbytes *= 2;
4593 row_info->bit_depth = 16;
4594 row_info->pixel_depth = (png_byte)(row_info->channels * 16);
4595 }
4596 }
4597 #endif
4598
4599 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4600 static void
png_do_quantize(png_row_infop row_info,png_bytep row,png_const_bytep palette_lookup,png_const_bytep quantize_lookup)4601 png_do_quantize(png_row_infop row_info, png_bytep row,
4602 png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
4603 {
4604 png_bytep sp, dp;
4605 png_uint_32 i;
4606 png_uint_32 row_width=row_info->width;
4607
4608 png_debug(1, "in png_do_quantize");
4609
4610 if (row_info->bit_depth == 8)
4611 {
4612 if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup)
4613 {
4614 int r, g, b, p;
4615 sp = row;
4616 dp = row;
4617 for (i = 0; i < row_width; i++)
4618 {
4619 r = *sp++;
4620 g = *sp++;
4621 b = *sp++;
4622
4623 /* This looks real messy, but the compiler will reduce
4624 * it down to a reasonable formula. For example, with
4625 * 5 bits per color, we get:
4626 * p = (((r >> 3) & 0x1f) << 10) |
4627 * (((g >> 3) & 0x1f) << 5) |
4628 * ((b >> 3) & 0x1f);
4629 */
4630 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4631 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4632 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4633 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4634 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4635 (PNG_QUANTIZE_BLUE_BITS)) |
4636 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4637 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4638
4639 *dp++ = palette_lookup[p];
4640 }
4641
4642 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4643 row_info->channels = 1;
4644 row_info->pixel_depth = row_info->bit_depth;
4645 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4646 }
4647
4648 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
4649 palette_lookup != NULL)
4650 {
4651 int r, g, b, p;
4652 sp = row;
4653 dp = row;
4654 for (i = 0; i < row_width; i++)
4655 {
4656 r = *sp++;
4657 g = *sp++;
4658 b = *sp++;
4659 sp++;
4660
4661 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4662 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4663 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4664 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4665 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4666 (PNG_QUANTIZE_BLUE_BITS)) |
4667 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4668 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4669
4670 *dp++ = palette_lookup[p];
4671 }
4672
4673 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4674 row_info->channels = 1;
4675 row_info->pixel_depth = row_info->bit_depth;
4676 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4677 }
4678
4679 else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4680 quantize_lookup)
4681 {
4682 sp = row;
4683
4684 for (i = 0; i < row_width; i++, sp++)
4685 {
4686 *sp = quantize_lookup[*sp];
4687 }
4688 }
4689 }
4690 }
4691 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
4692
4693 /* Transform the row. The order of transformations is significant,
4694 * and is very touchy. If you add a transformation, take care to
4695 * decide how it fits in with the other transformations here.
4696 */
4697 void /* PRIVATE */
png_do_read_transformations(png_structrp png_ptr,png_row_infop row_info)4698 png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
4699 {
4700 png_debug(1, "in png_do_read_transformations");
4701
4702 if (png_ptr->row_buf == NULL)
4703 {
4704 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
4705 * error is incredibly rare and incredibly easy to debug without this
4706 * information.
4707 */
4708 png_error(png_ptr, "NULL row buffer");
4709 }
4710
4711 /* The following is debugging; prior to 1.5.4 the code was never compiled in;
4712 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
4713 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for
4714 * all transformations, however in practice the ROW_INIT always gets done on
4715 * demand, if necessary.
4716 */
4717 if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
4718 !(png_ptr->flags & PNG_FLAG_ROW_INIT))
4719 {
4720 /* Application has failed to call either png_read_start_image() or
4721 * png_read_update_info() after setting transforms that expand pixels.
4722 * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
4723 */
4724 png_error(png_ptr, "Uninitialized row");
4725 }
4726
4727 #ifdef PNG_READ_EXPAND_SUPPORTED
4728 if (png_ptr->transformations & PNG_EXPAND)
4729 {
4730 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4731 {
4732 png_do_expand_palette(row_info, png_ptr->row_buf + 1,
4733 png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
4734 }
4735
4736 else
4737 {
4738 if (png_ptr->num_trans &&
4739 (png_ptr->transformations & PNG_EXPAND_tRNS))
4740 png_do_expand(row_info, png_ptr->row_buf + 1,
4741 &(png_ptr->trans_color));
4742
4743 else
4744 png_do_expand(row_info, png_ptr->row_buf + 1,
4745 NULL);
4746 }
4747 }
4748 #endif
4749
4750 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4751 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
4752 !(png_ptr->transformations & PNG_COMPOSE) &&
4753 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4754 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4755 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4756 0 /* at_start == false, because SWAP_ALPHA happens later */);
4757 #endif
4758
4759 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4760 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
4761 {
4762 int rgb_error =
4763 png_do_rgb_to_gray(png_ptr, row_info,
4764 png_ptr->row_buf + 1);
4765
4766 if (rgb_error)
4767 {
4768 png_ptr->rgb_to_gray_status=1;
4769 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4770 PNG_RGB_TO_GRAY_WARN)
4771 png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4772
4773 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4774 PNG_RGB_TO_GRAY_ERR)
4775 png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4776 }
4777 }
4778 #endif
4779
4780 /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
4781 *
4782 * In most cases, the "simple transparency" should be done prior to doing
4783 * gray-to-RGB, or you will have to test 3x as many bytes to check if a
4784 * pixel is transparent. You would also need to make sure that the
4785 * transparency information is upgraded to RGB.
4786 *
4787 * To summarize, the current flow is:
4788 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
4789 * with background "in place" if transparent,
4790 * convert to RGB if necessary
4791 * - Gray + alpha -> composite with gray background and remove alpha bytes,
4792 * convert to RGB if necessary
4793 *
4794 * To support RGB backgrounds for gray images we need:
4795 * - Gray + simple transparency -> convert to RGB + simple transparency,
4796 * compare 3 or 6 bytes and composite with
4797 * background "in place" if transparent
4798 * (3x compare/pixel compared to doing
4799 * composite with gray bkgrnd)
4800 * - Gray + alpha -> convert to RGB + alpha, composite with background and
4801 * remove alpha bytes (3x float
4802 * operations/pixel compared with composite
4803 * on gray background)
4804 *
4805 * Greg's change will do this. The reason it wasn't done before is for
4806 * performance, as this increases the per-pixel operations. If we would check
4807 * in advance if the background was gray or RGB, and position the gray-to-RGB
4808 * transform appropriately, then it would save a lot of work/time.
4809 */
4810
4811 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4812 /* If gray -> RGB, do so now only if background is non-gray; else do later
4813 * for performance reasons
4814 */
4815 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
4816 !(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
4817 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4818 #endif
4819
4820 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4821 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4822 if (png_ptr->transformations & PNG_COMPOSE)
4823 png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
4824 #endif
4825
4826 #ifdef PNG_READ_GAMMA_SUPPORTED
4827 if ((png_ptr->transformations & PNG_GAMMA) &&
4828 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4829 /* Because RGB_TO_GRAY does the gamma transform. */
4830 !(png_ptr->transformations & PNG_RGB_TO_GRAY) &&
4831 #endif
4832 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4833 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4834 /* Because PNG_COMPOSE does the gamma transform if there is something to
4835 * do (if there is an alpha channel or transparency.)
4836 */
4837 !((png_ptr->transformations & PNG_COMPOSE) &&
4838 ((png_ptr->num_trans != 0) ||
4839 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) &&
4840 #endif
4841 /* Because png_init_read_transformations transforms the palette, unless
4842 * RGB_TO_GRAY will do the transform.
4843 */
4844 (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
4845 png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
4846 #endif
4847
4848 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4849 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
4850 (png_ptr->transformations & PNG_COMPOSE) &&
4851 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4852 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4853 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4854 0 /* at_start == false, because SWAP_ALPHA happens later */);
4855 #endif
4856
4857 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4858 if ((png_ptr->transformations & PNG_ENCODE_ALPHA) &&
4859 (row_info->color_type & PNG_COLOR_MASK_ALPHA))
4860 png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
4861 #endif
4862
4863 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
4864 if (png_ptr->transformations & PNG_SCALE_16_TO_8)
4865 png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
4866 #endif
4867
4868 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
4869 /* There is no harm in doing both of these because only one has any effect,
4870 * by putting the 'scale' option first if the app asks for scale (either by
4871 * calling the API or in a TRANSFORM flag) this is what happens.
4872 */
4873 if (png_ptr->transformations & PNG_16_TO_8)
4874 png_do_chop(row_info, png_ptr->row_buf + 1);
4875 #endif
4876
4877 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4878 if (png_ptr->transformations & PNG_QUANTIZE)
4879 {
4880 png_do_quantize(row_info, png_ptr->row_buf + 1,
4881 png_ptr->palette_lookup, png_ptr->quantize_index);
4882
4883 if (row_info->rowbytes == 0)
4884 png_error(png_ptr, "png_do_quantize returned rowbytes=0");
4885 }
4886 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
4887
4888 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4889 /* Do the expansion now, after all the arithmetic has been done. Notice
4890 * that previous transformations can handle the PNG_EXPAND_16 flag if this
4891 * is efficient (particularly true in the case of gamma correction, where
4892 * better accuracy results faster!)
4893 */
4894 if (png_ptr->transformations & PNG_EXPAND_16)
4895 png_do_expand_16(row_info, png_ptr->row_buf + 1);
4896 #endif
4897
4898 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4899 /* NOTE: moved here in 1.5.4 (from much later in this list.) */
4900 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
4901 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
4902 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4903 #endif
4904
4905 #ifdef PNG_READ_INVERT_SUPPORTED
4906 if (png_ptr->transformations & PNG_INVERT_MONO)
4907 png_do_invert(row_info, png_ptr->row_buf + 1);
4908 #endif
4909
4910 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
4911 if (png_ptr->transformations & PNG_INVERT_ALPHA)
4912 png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
4913 #endif
4914
4915 #ifdef PNG_READ_SHIFT_SUPPORTED
4916 if (png_ptr->transformations & PNG_SHIFT)
4917 png_do_unshift(row_info, png_ptr->row_buf + 1,
4918 &(png_ptr->shift));
4919 #endif
4920
4921 #ifdef PNG_READ_PACK_SUPPORTED
4922 if (png_ptr->transformations & PNG_PACK)
4923 png_do_unpack(row_info, png_ptr->row_buf + 1);
4924 #endif
4925
4926 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
4927 /* Added at libpng-1.5.10 */
4928 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4929 png_ptr->num_palette_max >= 0)
4930 png_do_check_palette_indexes(png_ptr, row_info);
4931 #endif
4932
4933 #ifdef PNG_READ_BGR_SUPPORTED
4934 if (png_ptr->transformations & PNG_BGR)
4935 png_do_bgr(row_info, png_ptr->row_buf + 1);
4936 #endif
4937
4938 #ifdef PNG_READ_PACKSWAP_SUPPORTED
4939 if (png_ptr->transformations & PNG_PACKSWAP)
4940 png_do_packswap(row_info, png_ptr->row_buf + 1);
4941 #endif
4942
4943 #ifdef PNG_READ_FILLER_SUPPORTED
4944 if (png_ptr->transformations & PNG_FILLER)
4945 png_do_read_filler(row_info, png_ptr->row_buf + 1,
4946 (png_uint_32)png_ptr->filler, png_ptr->flags);
4947 #endif
4948
4949 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
4950 if (png_ptr->transformations & PNG_SWAP_ALPHA)
4951 png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
4952 #endif
4953
4954 #ifdef PNG_READ_16BIT_SUPPORTED
4955 #ifdef PNG_READ_SWAP_SUPPORTED
4956 if (png_ptr->transformations & PNG_SWAP_BYTES)
4957 png_do_swap(row_info, png_ptr->row_buf + 1);
4958 #endif
4959 #endif
4960
4961 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
4962 if (png_ptr->transformations & PNG_USER_TRANSFORM)
4963 {
4964 if (png_ptr->read_user_transform_fn != NULL)
4965 (*(png_ptr->read_user_transform_fn)) /* User read transform function */
4966 (png_ptr, /* png_ptr */
4967 row_info, /* row_info: */
4968 /* png_uint_32 width; width of row */
4969 /* png_size_t rowbytes; number of bytes in row */
4970 /* png_byte color_type; color type of pixels */
4971 /* png_byte bit_depth; bit depth of samples */
4972 /* png_byte channels; number of channels (1-4) */
4973 /* png_byte pixel_depth; bits per pixel (depth*channels) */
4974 png_ptr->row_buf + 1); /* start of pixel data for row */
4975 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
4976 if (png_ptr->user_transform_depth)
4977 row_info->bit_depth = png_ptr->user_transform_depth;
4978
4979 if (png_ptr->user_transform_channels)
4980 row_info->channels = png_ptr->user_transform_channels;
4981 #endif
4982 row_info->pixel_depth = (png_byte)(row_info->bit_depth *
4983 row_info->channels);
4984
4985 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
4986 }
4987 #endif
4988 }
4989
4990 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
4991 #endif /* PNG_READ_SUPPORTED */
4992