1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* pngrtran.c - transforms the data in a row for PNG readers
26 *
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file and, per its terms, should not be removed:
31 *
32 * Copyright (c) 2018-2019 Cosmin Truta
33 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
34 * Copyright (c) 1996-1997 Andreas Dilger
35 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
36 *
37 * This code is released under the libpng license.
38 * For conditions of distribution and use, see the disclaimer
39 * and license in png.h
40 *
41 * This file contains functions optionally called by an application
42 * in order to tell libpng how to handle data when reading a PNG.
43 * Transformations that are used in both reading and writing are
44 * in pngtrans.c.
45 */
46
47 #include "pngpriv.h"
48
49 #ifdef PNG_ARM_NEON_IMPLEMENTATION
50 # if PNG_ARM_NEON_IMPLEMENTATION == 1
51 # define PNG_ARM_NEON_INTRINSICS_AVAILABLE
52 # if defined(_MSC_VER) && defined(_M_ARM64)
53 # include <arm64_neon.h>
54 # else
55 # include <arm_neon.h>
56 # endif
57 # endif
58 #endif
59
60 #ifdef PNG_READ_SUPPORTED
61
62 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
63 void PNGAPI
64 png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
65 {
66 png_debug(1, "in png_set_crc_action");
67
68 if (png_ptr == NULL)
69 return;
70
71 /* Tell libpng how we react to CRC errors in critical chunks */
72 switch (crit_action)
73 {
74 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
75 break;
76
77 case PNG_CRC_WARN_USE: /* Warn/use data */
78 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
79 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
80 break;
81
82 case PNG_CRC_QUIET_USE: /* Quiet/use data */
83 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
84 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
85 PNG_FLAG_CRC_CRITICAL_IGNORE;
86 break;
87
88 case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */
89 png_warning(png_ptr,
90 "Can't discard critical data on CRC error");
91 /* FALLTHROUGH */
92 case PNG_CRC_ERROR_QUIT: /* Error/quit */
93
94 case PNG_CRC_DEFAULT:
95 default:
96 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
97 break;
98 }
99
100 /* Tell libpng how we react to CRC errors in ancillary chunks */
101 switch (ancil_action)
102 {
103 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
104 break;
105
106 case PNG_CRC_WARN_USE: /* Warn/use data */
107 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
108 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
109 break;
110
111 case PNG_CRC_QUIET_USE: /* Quiet/use data */
112 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
113 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
114 PNG_FLAG_CRC_ANCILLARY_NOWARN;
115 break;
116
117 case PNG_CRC_ERROR_QUIT: /* Error/quit */
118 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
119 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
120 break;
121
122 case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
123
124 case PNG_CRC_DEFAULT:
125 default:
126 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
127 break;
128 }
129 }
130
131 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
132 /* Is it OK to set a transformation now? Only if png_start_read_image or
133 * png_read_update_info have not been called. It is not necessary for the IHDR
134 * to have been read in all cases; the need_IHDR parameter allows for this
135 * check too.
136 */
137 static int
138 png_rtran_ok(png_structrp png_ptr, int need_IHDR)
139 {
140 if (png_ptr != NULL)
141 {
142 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
143 png_app_error(png_ptr,
144 "invalid after png_start_read_image or png_read_update_info");
145
146 else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
147 png_app_error(png_ptr, "invalid before the PNG header has been read");
148
149 else
150 {
151 /* Turn on failure to initialize correctly for all transforms. */
152 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
153
154 return 1; /* Ok */
155 }
156 }
157
158 return 0; /* no png_error possible! */
159 }
160 #endif
161
162 #ifdef PNG_READ_BACKGROUND_SUPPORTED
163 /* Handle alpha and tRNS via a background color */
164 void PNGFAPI
165 png_set_background_fixed(png_structrp png_ptr,
166 png_const_color_16p background_color, int background_gamma_code,
167 int need_expand, png_fixed_point background_gamma)
168 {
169 png_debug(1, "in png_set_background_fixed");
170
171 if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL)
172 return;
173
174 if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
175 {
176 png_warning(png_ptr, "Application must supply a known background gamma");
177 return;
178 }
179
180 png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
181 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
182 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
183
184 png_ptr->background = *background_color;
185 png_ptr->background_gamma = background_gamma;
186 png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
187 if (need_expand != 0)
188 png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
189 else
190 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
191 }
192
193 # ifdef PNG_FLOATING_POINT_SUPPORTED
194 void PNGAPI
195 png_set_background(png_structrp png_ptr,
196 png_const_color_16p background_color, int background_gamma_code,
197 int need_expand, double background_gamma)
198 {
199 png_set_background_fixed(png_ptr, background_color, background_gamma_code,
200 need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
201 }
202 # endif /* FLOATING_POINT */
203 #endif /* READ_BACKGROUND */
204
205 /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
206 * one that pngrtran does first (scale) happens. This is necessary to allow the
207 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
208 */
209 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
210 void PNGAPI
211 png_set_scale_16(png_structrp png_ptr)
212 {
213 png_debug(1, "in png_set_scale_16");
214
215 if (png_rtran_ok(png_ptr, 0) == 0)
216 return;
217
218 png_ptr->transformations |= PNG_SCALE_16_TO_8;
219 }
220 #endif
221
222 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
223 /* Chop 16-bit depth files to 8-bit depth */
224 void PNGAPI
225 png_set_strip_16(png_structrp png_ptr)
226 {
227 png_debug(1, "in png_set_strip_16");
228
229 if (png_rtran_ok(png_ptr, 0) == 0)
230 return;
231
232 png_ptr->transformations |= PNG_16_TO_8;
233 }
234 #endif
235
236 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
237 void PNGAPI
238 png_set_strip_alpha(png_structrp png_ptr)
239 {
240 png_debug(1, "in png_set_strip_alpha");
241
242 if (png_rtran_ok(png_ptr, 0) == 0)
243 return;
244
245 png_ptr->transformations |= PNG_STRIP_ALPHA;
246 }
247 #endif
248
249 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
250 static png_fixed_point
251 translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
252 int is_screen)
253 {
254 /* Check for flag values. The main reason for having the old Mac value as a
255 * flag is that it is pretty near impossible to work out what the correct
256 * value is from Apple documentation - a working Mac system is needed to
257 * discover the value!
258 */
259 if (output_gamma == PNG_DEFAULT_sRGB ||
260 output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
261 {
262 /* If there is no sRGB support this just sets the gamma to the standard
263 * sRGB value. (This is a side effect of using this function!)
264 */
265 # ifdef PNG_READ_sRGB_SUPPORTED
266 png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
267 # else
268 PNG_UNUSED(png_ptr)
269 # endif
270 if (is_screen != 0)
271 output_gamma = PNG_GAMMA_sRGB;
272 else
273 output_gamma = PNG_GAMMA_sRGB_INVERSE;
274 }
275
276 else if (output_gamma == PNG_GAMMA_MAC_18 ||
277 output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
278 {
279 if (is_screen != 0)
280 output_gamma = PNG_GAMMA_MAC_OLD;
281 else
282 output_gamma = PNG_GAMMA_MAC_INVERSE;
283 }
284
285 return output_gamma;
286 }
287
288 # ifdef PNG_FLOATING_POINT_SUPPORTED
289 static png_fixed_point
290 convert_gamma_value(png_structrp png_ptr, double output_gamma)
291 {
292 /* The following silently ignores cases where fixed point (times 100,000)
293 * gamma values are passed to the floating point API. This is safe and it
294 * means the fixed point constants work just fine with the floating point
295 * API. The alternative would just lead to undetected errors and spurious
296 * bug reports. Negative values fail inside the _fixed API unless they
297 * correspond to the flag values.
298 */
299 if (output_gamma > 0 && output_gamma < 128)
300 output_gamma *= PNG_FP_1;
301
302 /* This preserves -1 and -2 exactly: */
303 output_gamma = floor(output_gamma + .5);
304
305 if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
306 png_fixed_error(png_ptr, "gamma value");
307
308 return (png_fixed_point)output_gamma;
309 }
310 # endif
311 #endif /* READ_ALPHA_MODE || READ_GAMMA */
312
313 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
314 void PNGFAPI
315 png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
316 png_fixed_point output_gamma)
317 {
318 int compose = 0;
319 png_fixed_point file_gamma;
320
321 png_debug(1, "in png_set_alpha_mode");
322
323 if (png_rtran_ok(png_ptr, 0) == 0)
324 return;
325
326 output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
327
328 /* Validate the value to ensure it is in a reasonable range. The value
329 * is expected to be 1 or greater, but this range test allows for some
330 * viewing correction values. The intent is to weed out users of this API
331 * who use the inverse of the gamma value accidentally! Since some of these
332 * values are reasonable this may have to be changed:
333 *
334 * 1.6.x: changed from 0.07..3 to 0.01..100 (to accommodate the optimal 16-bit
335 * gamma of 36, and its reciprocal.)
336 */
337 if (output_gamma < 1000 || output_gamma > 10000000)
338 png_error(png_ptr, "output gamma out of expected range");
339
340 /* The default file gamma is the inverse of the output gamma; the output
341 * gamma may be changed below so get the file value first:
342 */
343 file_gamma = png_reciprocal(output_gamma);
344
345 /* There are really 8 possibilities here, composed of any combination
346 * of:
347 *
348 * premultiply the color channels
349 * do not encode non-opaque pixels
350 * encode the alpha as well as the color channels
351 *
352 * The differences disappear if the input/output ('screen') gamma is 1.0,
353 * because then the encoding is a no-op and there is only the choice of
354 * premultiplying the color channels or not.
355 *
356 * png_set_alpha_mode and png_set_background interact because both use
357 * png_compose to do the work. Calling both is only useful when
358 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
359 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
360 */
361 switch (mode)
362 {
363 case PNG_ALPHA_PNG: /* default: png standard */
364 /* No compose, but it may be set by png_set_background! */
365 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
366 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
367 break;
368
369 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
370 compose = 1;
371 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
372 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
373 /* The output is linear: */
374 output_gamma = PNG_FP_1;
375 break;
376
377 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
378 compose = 1;
379 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
380 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
381 /* output_gamma records the encoding of opaque pixels! */
382 break;
383
384 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
385 compose = 1;
386 png_ptr->transformations |= PNG_ENCODE_ALPHA;
387 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
388 break;
389
390 default:
391 png_error(png_ptr, "invalid alpha mode");
392 }
393
394 /* Only set the default gamma if the file gamma has not been set (this has
395 * the side effect that the gamma in a second call to png_set_alpha_mode will
396 * be ignored.)
397 */
398 if (png_ptr->colorspace.gamma == 0)
399 {
400 png_ptr->colorspace.gamma = file_gamma;
401 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
402 }
403
404 /* But always set the output gamma: */
405 png_ptr->screen_gamma = output_gamma;
406
407 /* Finally, if pre-multiplying, set the background fields to achieve the
408 * desired result.
409 */
410 if (compose != 0)
411 {
412 /* And obtain alpha pre-multiplication by composing on black: */
413 memset(&png_ptr->background, 0, (sizeof png_ptr->background));
414 png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
415 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
416 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
417
418 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
419 png_error(png_ptr,
420 "conflicting calls to set alpha mode and background");
421
422 png_ptr->transformations |= PNG_COMPOSE;
423 }
424 }
425
426 # ifdef PNG_FLOATING_POINT_SUPPORTED
427 void PNGAPI
428 png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
429 {
430 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
431 output_gamma));
432 }
433 # endif
434 #endif
435
436 #ifdef PNG_READ_QUANTIZE_SUPPORTED
437 /* Dither file to 8-bit. Supply a palette, the current number
438 * of elements in the palette, the maximum number of elements
439 * allowed, and a histogram if possible. If the current number
440 * of colors is greater than the maximum number, the palette will be
441 * modified to fit in the maximum number. "full_quantize" indicates
442 * whether we need a quantizing cube set up for RGB images, or if we
443 * simply are reducing the number of colors in a paletted image.
444 */
445
446 typedef struct png_dsort_struct
447 {
448 struct png_dsort_struct * next;
449 png_byte left;
450 png_byte right;
451 } png_dsort;
452 typedef png_dsort * png_dsortp;
453 typedef png_dsort * * png_dsortpp;
454
455 void PNGAPI
456 png_set_quantize(png_structrp png_ptr, png_colorp palette,
457 int num_palette, int maximum_colors, png_const_uint_16p histogram,
458 int full_quantize)
459 {
460 png_debug(1, "in png_set_quantize");
461
462 if (png_rtran_ok(png_ptr, 0) == 0)
463 return;
464
465 png_ptr->transformations |= PNG_QUANTIZE;
466
467 if (full_quantize == 0)
468 {
469 int i;
470
471 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
472 (png_alloc_size_t)((png_uint_32)num_palette * (sizeof (png_byte))));
473 for (i = 0; i < num_palette; i++)
474 png_ptr->quantize_index[i] = (png_byte)i;
475 }
476
477 if (num_palette > maximum_colors)
478 {
479 if (histogram != NULL)
480 {
481 /* This is easy enough, just throw out the least used colors.
482 * Perhaps not the best solution, but good enough.
483 */
484
485 int i;
486
487 /* Initialize an array to sort colors */
488 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
489 (png_alloc_size_t)((png_uint_32)num_palette * (sizeof (png_byte))));
490
491 /* Initialize the quantize_sort array */
492 for (i = 0; i < num_palette; i++)
493 png_ptr->quantize_sort[i] = (png_byte)i;
494
495 /* Find the least used palette entries by starting a
496 * bubble sort, and running it until we have sorted
497 * out enough colors. Note that we don't care about
498 * sorting all the colors, just finding which are
499 * least used.
500 */
501
502 for (i = num_palette - 1; i >= maximum_colors; i--)
503 {
504 int done; /* To stop early if the list is pre-sorted */
505 int j;
506
507 done = 1;
508 for (j = 0; j < i; j++)
509 {
510 if (histogram[png_ptr->quantize_sort[j]]
511 < histogram[png_ptr->quantize_sort[j + 1]])
512 {
513 png_byte t;
514
515 t = png_ptr->quantize_sort[j];
516 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
517 png_ptr->quantize_sort[j + 1] = t;
518 done = 0;
519 }
520 }
521
522 if (done != 0)
523 break;
524 }
525
526 /* Swap the palette around, and set up a table, if necessary */
527 if (full_quantize != 0)
528 {
529 int j = num_palette;
530
531 /* Put all the useful colors within the max, but don't
532 * move the others.
533 */
534 for (i = 0; i < maximum_colors; i++)
535 {
536 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
537 {
538 do
539 j--;
540 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
541
542 palette[i] = palette[j];
543 }
544 }
545 }
546 else
547 {
548 int j = num_palette;
549
550 /* Move all the used colors inside the max limit, and
551 * develop a translation table.
552 */
553 for (i = 0; i < maximum_colors; i++)
554 {
555 /* Only move the colors we need to */
556 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
557 {
558 png_color tmp_color;
559
560 do
561 j--;
562 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
563
564 tmp_color = palette[j];
565 palette[j] = palette[i];
566 palette[i] = tmp_color;
567 /* Indicate where the color went */
568 png_ptr->quantize_index[j] = (png_byte)i;
569 png_ptr->quantize_index[i] = (png_byte)j;
570 }
571 }
572
573 /* Find closest color for those colors we are not using */
574 for (i = 0; i < num_palette; i++)
575 {
576 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
577 {
578 int min_d, k, min_k, d_index;
579
580 /* Find the closest color to one we threw out */
581 d_index = png_ptr->quantize_index[i];
582 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
583 for (k = 1, min_k = 0; k < maximum_colors; k++)
584 {
585 int d;
586
587 d = PNG_COLOR_DIST(palette[d_index], palette[k]);
588
589 if (d < min_d)
590 {
591 min_d = d;
592 min_k = k;
593 }
594 }
595 /* Point to closest color */
596 png_ptr->quantize_index[i] = (png_byte)min_k;
597 }
598 }
599 }
600 png_free(png_ptr, png_ptr->quantize_sort);
601 png_ptr->quantize_sort = NULL;
602 }
603 else
604 {
605 /* This is much harder to do simply (and quickly). Perhaps
606 * we need to go through a median cut routine, but those
607 * don't always behave themselves with only a few colors
608 * as input. So we will just find the closest two colors,
609 * and throw out one of them (chosen somewhat randomly).
610 * [We don't understand this at all, so if someone wants to
611 * work on improving it, be our guest - AED, GRP]
612 */
613 int i;
614 int max_d;
615 int num_new_palette;
616 png_dsortp t;
617 png_dsortpp hash;
618
619 t = NULL;
620
621 /* Initialize palette index arrays */
622 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
623 (png_alloc_size_t)((png_uint_32)num_palette *
624 (sizeof (png_byte))));
625 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
626 (png_alloc_size_t)((png_uint_32)num_palette *
627 (sizeof (png_byte))));
628
629 /* Initialize the sort array */
630 for (i = 0; i < num_palette; i++)
631 {
632 png_ptr->index_to_palette[i] = (png_byte)i;
633 png_ptr->palette_to_index[i] = (png_byte)i;
634 }
635
636 hash = (png_dsortpp)png_calloc(png_ptr, (png_alloc_size_t)(769 *
637 (sizeof (png_dsortp))));
638
639 num_new_palette = num_palette;
640
641 /* Initial wild guess at how far apart the farthest pixel
642 * pair we will be eliminating will be. Larger
643 * numbers mean more areas will be allocated, Smaller
644 * numbers run the risk of not saving enough data, and
645 * having to do this all over again.
646 *
647 * I have not done extensive checking on this number.
648 */
649 max_d = 96;
650
651 while (num_new_palette > maximum_colors)
652 {
653 for (i = 0; i < num_new_palette - 1; i++)
654 {
655 int j;
656
657 for (j = i + 1; j < num_new_palette; j++)
658 {
659 int d;
660
661 d = PNG_COLOR_DIST(palette[i], palette[j]);
662
663 if (d <= max_d)
664 {
665
666 t = (png_dsortp)png_malloc_warn(png_ptr,
667 (png_alloc_size_t)(sizeof (png_dsort)));
668
669 if (t == NULL)
670 break;
671
672 t->next = hash[d];
673 t->left = (png_byte)i;
674 t->right = (png_byte)j;
675 hash[d] = t;
676 }
677 }
678 if (t == NULL)
679 break;
680 }
681
682 if (t != NULL)
683 for (i = 0; i <= max_d; i++)
684 {
685 if (hash[i] != NULL)
686 {
687 png_dsortp p;
688
689 for (p = hash[i]; p; p = p->next)
690 {
691 if ((int)png_ptr->index_to_palette[p->left]
692 < num_new_palette &&
693 (int)png_ptr->index_to_palette[p->right]
694 < num_new_palette)
695 {
696 int j, next_j;
697
698 if (num_new_palette & 0x01)
699 {
700 j = p->left;
701 next_j = p->right;
702 }
703 else
704 {
705 j = p->right;
706 next_j = p->left;
707 }
708
709 num_new_palette--;
710 palette[png_ptr->index_to_palette[j]]
711 = palette[num_new_palette];
712 if (full_quantize == 0)
713 {
714 int k;
715
716 for (k = 0; k < num_palette; k++)
717 {
718 if (png_ptr->quantize_index[k] ==
719 png_ptr->index_to_palette[j])
720 png_ptr->quantize_index[k] =
721 png_ptr->index_to_palette[next_j];
722
723 if ((int)png_ptr->quantize_index[k] ==
724 num_new_palette)
725 png_ptr->quantize_index[k] =
726 png_ptr->index_to_palette[j];
727 }
728 }
729
730 png_ptr->index_to_palette[png_ptr->palette_to_index
731 [num_new_palette]] = png_ptr->index_to_palette[j];
732
733 png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
734 = png_ptr->palette_to_index[num_new_palette];
735
736 png_ptr->index_to_palette[j] =
737 (png_byte)num_new_palette;
738
739 png_ptr->palette_to_index[num_new_palette] =
740 (png_byte)j;
741 }
742 if (num_new_palette <= maximum_colors)
743 break;
744 }
745 if (num_new_palette <= maximum_colors)
746 break;
747 }
748 }
749
750 for (i = 0; i < 769; i++)
751 {
752 if (hash[i] != NULL)
753 {
754 png_dsortp p = hash[i];
755 while (p)
756 {
757 t = p->next;
758 png_free(png_ptr, p);
759 p = t;
760 }
761 }
762 hash[i] = 0;
763 }
764 max_d += 96;
765 }
766 png_free(png_ptr, hash);
767 png_free(png_ptr, png_ptr->palette_to_index);
768 png_free(png_ptr, png_ptr->index_to_palette);
769 png_ptr->palette_to_index = NULL;
770 png_ptr->index_to_palette = NULL;
771 }
772 num_palette = maximum_colors;
773 }
774 if (png_ptr->palette == NULL)
775 {
776 png_ptr->palette = palette;
777 }
778 png_ptr->num_palette = (png_uint_16)num_palette;
779
780 if (full_quantize != 0)
781 {
782 int i;
783 png_bytep distance;
784 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
785 PNG_QUANTIZE_BLUE_BITS;
786 int num_red = (1 << PNG_QUANTIZE_RED_BITS);
787 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
788 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
789 size_t num_entries = ((size_t)1 << total_bits);
790
791 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
792 (png_alloc_size_t)(num_entries * (sizeof (png_byte))));
793
794 distance = (png_bytep)png_malloc(png_ptr, (png_alloc_size_t)(num_entries *
795 (sizeof (png_byte))));
796
797 memset(distance, 0xff, num_entries * (sizeof (png_byte)));
798
799 for (i = 0; i < num_palette; i++)
800 {
801 int ir, ig, ib;
802 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
803 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
804 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
805
806 for (ir = 0; ir < num_red; ir++)
807 {
808 /* int dr = abs(ir - r); */
809 int dr = ((ir > r) ? ir - r : r - ir);
810 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
811 PNG_QUANTIZE_GREEN_BITS));
812
813 for (ig = 0; ig < num_green; ig++)
814 {
815 /* int dg = abs(ig - g); */
816 int dg = ((ig > g) ? ig - g : g - ig);
817 int dt = dr + dg;
818 int dm = ((dr > dg) ? dr : dg);
819 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
820
821 for (ib = 0; ib < num_blue; ib++)
822 {
823 int d_index = index_g | ib;
824 /* int db = abs(ib - b); */
825 int db = ((ib > b) ? ib - b : b - ib);
826 int dmax = ((dm > db) ? dm : db);
827 int d = dmax + dt + db;
828
829 if (d < (int)distance[d_index])
830 {
831 distance[d_index] = (png_byte)d;
832 png_ptr->palette_lookup[d_index] = (png_byte)i;
833 }
834 }
835 }
836 }
837 }
838
839 png_free(png_ptr, distance);
840 }
841 }
842 #endif /* READ_QUANTIZE */
843
844 #ifdef PNG_READ_GAMMA_SUPPORTED
845 void PNGFAPI
846 png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
847 png_fixed_point file_gamma)
848 {
849 png_debug(1, "in png_set_gamma_fixed");
850
851 if (png_rtran_ok(png_ptr, 0) == 0)
852 return;
853
854 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
855 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
856 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
857
858 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
859 * premultiplied alpha support; this actually hides an undocumented feature
860 * of the previous implementation which allowed gamma processing to be
861 * disabled in background handling. There is no evidence (so far) that this
862 * was being used; however, png_set_background itself accepted and must still
863 * accept '0' for the gamma value it takes, because it isn't always used.
864 *
865 * Since this is an API change (albeit a very minor one that removes an
866 * undocumented API feature) the following checks were only enabled in
867 * libpng-1.6.0.
868 */
869 if (file_gamma <= 0)
870 png_error(png_ptr, "invalid file gamma in png_set_gamma");
871
872 if (scrn_gamma <= 0)
873 png_error(png_ptr, "invalid screen gamma in png_set_gamma");
874
875 /* Set the gamma values unconditionally - this overrides the value in the PNG
876 * file if a gAMA chunk was present. png_set_alpha_mode provides a
877 * different, easier, way to default the file gamma.
878 */
879 png_ptr->colorspace.gamma = file_gamma;
880 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
881 png_ptr->screen_gamma = scrn_gamma;
882 }
883
884 # ifdef PNG_FLOATING_POINT_SUPPORTED
885 void PNGAPI
886 png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
887 {
888 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
889 convert_gamma_value(png_ptr, file_gamma));
890 }
891 # endif /* FLOATING_POINT */
892 #endif /* READ_GAMMA */
893
894 #ifdef PNG_READ_EXPAND_SUPPORTED
895 /* Expand paletted images to RGB, expand grayscale images of
896 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
897 * to alpha channels.
898 */
899 void PNGAPI
900 png_set_expand(png_structrp png_ptr)
901 {
902 png_debug(1, "in png_set_expand");
903
904 if (png_rtran_ok(png_ptr, 0) == 0)
905 return;
906
907 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
908 }
909
910 /* GRR 19990627: the following three functions currently are identical
911 * to png_set_expand(). However, it is entirely reasonable that someone
912 * might wish to expand an indexed image to RGB but *not* expand a single,
913 * fully transparent palette entry to a full alpha channel--perhaps instead
914 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
915 * the transparent color with a particular RGB value, or drop tRNS entirely.
916 * IOW, a future version of the library may make the transformations flag
917 * a bit more fine-grained, with separate bits for each of these three
918 * functions.
919 *
920 * More to the point, these functions make it obvious what libpng will be
921 * doing, whereas "expand" can (and does) mean any number of things.
922 *
923 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
924 * to expand only the sample depth but not to expand the tRNS to alpha
925 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
926 */
927
928 /* Expand paletted images to RGB. */
929 void PNGAPI
930 png_set_palette_to_rgb(png_structrp png_ptr)
931 {
932 png_debug(1, "in png_set_palette_to_rgb");
933
934 if (png_rtran_ok(png_ptr, 0) == 0)
935 return;
936
937 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
938 }
939
940 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
941 void PNGAPI
942 png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
943 {
944 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
945
946 if (png_rtran_ok(png_ptr, 0) == 0)
947 return;
948
949 png_ptr->transformations |= PNG_EXPAND;
950 }
951
952 /* Expand tRNS chunks to alpha channels. */
953 void PNGAPI
954 png_set_tRNS_to_alpha(png_structrp png_ptr)
955 {
956 png_debug(1, "in png_set_tRNS_to_alpha");
957
958 if (png_rtran_ok(png_ptr, 0) == 0)
959 return;
960
961 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
962 }
963 #endif /* READ_EXPAND */
964
965 #ifdef PNG_READ_EXPAND_16_SUPPORTED
966 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
967 * it may not work correctly.)
968 */
969 void PNGAPI
970 png_set_expand_16(png_structrp png_ptr)
971 {
972 png_debug(1, "in png_set_expand_16");
973
974 if (png_rtran_ok(png_ptr, 0) == 0)
975 return;
976
977 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
978 }
979 #endif
980
981 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
982 void PNGAPI
983 png_set_gray_to_rgb(png_structrp png_ptr)
984 {
985 png_debug(1, "in png_set_gray_to_rgb");
986
987 if (png_rtran_ok(png_ptr, 0) == 0)
988 return;
989
990 /* Because rgb must be 8 bits or more: */
991 png_set_expand_gray_1_2_4_to_8(png_ptr);
992 png_ptr->transformations |= PNG_GRAY_TO_RGB;
993 }
994 #endif
995
996 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
997 void PNGFAPI
998 png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
999 png_fixed_point red, png_fixed_point green)
1000 {
1001 png_debug(1, "in png_set_rgb_to_gray");
1002
1003 /* Need the IHDR here because of the check on color_type below. */
1004 /* TODO: fix this */
1005 if (png_rtran_ok(png_ptr, 1) == 0)
1006 return;
1007
1008 switch (error_action)
1009 {
1010 case PNG_ERROR_ACTION_NONE:
1011 png_ptr->transformations |= PNG_RGB_TO_GRAY;
1012 break;
1013
1014 case PNG_ERROR_ACTION_WARN:
1015 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
1016 break;
1017
1018 case PNG_ERROR_ACTION_ERROR:
1019 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
1020 break;
1021
1022 default:
1023 png_error(png_ptr, "invalid error action to rgb_to_gray");
1024 }
1025
1026 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1027 #ifdef PNG_READ_EXPAND_SUPPORTED
1028 png_ptr->transformations |= PNG_EXPAND;
1029 #else
1030 {
1031 /* Make this an error in 1.6 because otherwise the application may assume
1032 * that it just worked and get a memory overwrite.
1033 */
1034 png_error(png_ptr,
1035 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
1036
1037 /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
1038 }
1039 #endif
1040 {
1041 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
1042 {
1043 png_uint_16 red_int, green_int;
1044
1045 /* NOTE: this calculation does not round, but this behavior is retained
1046 * for consistency; the inaccuracy is very small. The code here always
1047 * overwrites the coefficients, regardless of whether they have been
1048 * defaulted or set already.
1049 */
1050 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
1051 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
1052
1053 png_ptr->rgb_to_gray_red_coeff = red_int;
1054 png_ptr->rgb_to_gray_green_coeff = green_int;
1055 png_ptr->rgb_to_gray_coefficients_set = 1;
1056 }
1057
1058 else
1059 {
1060 if (red >= 0 && green >= 0)
1061 png_app_warning(png_ptr,
1062 "ignoring out of range rgb_to_gray coefficients");
1063
1064 /* Use the defaults, from the cHRM chunk if set, else the historical
1065 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
1066 * png_do_rgb_to_gray for more discussion of the values. In this case
1067 * the coefficients are not marked as 'set' and are not overwritten if
1068 * something has already provided a default.
1069 */
1070 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
1071 png_ptr->rgb_to_gray_green_coeff == 0)
1072 {
1073 png_ptr->rgb_to_gray_red_coeff = 6968;
1074 png_ptr->rgb_to_gray_green_coeff = 23434;
1075 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1076 }
1077 }
1078 }
1079 }
1080
1081 #ifdef PNG_FLOATING_POINT_SUPPORTED
1082 /* Convert a RGB image to a grayscale of the same width. This allows us,
1083 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1084 */
1085
1086 void PNGAPI
1087 png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
1088 double green)
1089 {
1090 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1091 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
1092 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
1093 }
1094 #endif /* FLOATING POINT */
1095
1096 #endif /* RGB_TO_GRAY */
1097
1098 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1099 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1100 void PNGAPI
1101 png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1102 read_user_transform_fn)
1103 {
1104 png_debug(1, "in png_set_read_user_transform_fn");
1105
1106 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1107 png_ptr->transformations |= PNG_USER_TRANSFORM;
1108 png_ptr->read_user_transform_fn = read_user_transform_fn;
1109 #endif
1110 }
1111 #endif
1112
1113 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1114 #ifdef PNG_READ_GAMMA_SUPPORTED
1115 /* In the case of gamma transformations only do transformations on images where
1116 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1117 * slows things down slightly, and also needlessly introduces small errors.
1118 */
1119 static int /* PRIVATE */
1120 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
1121 {
1122 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1123 * correction as a difference of the overall transform from 1.0
1124 *
1125 * We want to compare the threshold with s*f - 1, if we get
1126 * overflow here it is because of wacky gamma values so we
1127 * turn on processing anyway.
1128 */
1129 png_fixed_point gtest;
1130 return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) ||
1131 png_gamma_significant(gtest);
1132 }
1133 #endif
1134
1135 /* Initialize everything needed for the read. This includes modifying
1136 * the palette.
1137 */
1138
1139 /* For the moment 'png_init_palette_transformations' and
1140 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1141 * The intent is that these two routines should have palette or rgb operations
1142 * extracted from 'png_init_read_transformations'.
1143 */
1144 static void /* PRIVATE */
1145 png_init_palette_transformations(png_structrp png_ptr)
1146 {
1147 /* Called to handle the (input) palette case. In png_do_read_transformations
1148 * the first step is to expand the palette if requested, so this code must
1149 * take care to only make changes that are invariant with respect to the
1150 * palette expansion, or only do them if there is no expansion.
1151 *
1152 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1153 * to 0.)
1154 */
1155 int input_has_alpha = 0;
1156 int input_has_transparency = 0;
1157
1158 if (png_ptr->num_trans > 0)
1159 {
1160 int i;
1161
1162 /* Ignore if all the entries are opaque (unlikely!) */
1163 for (i=0; i<png_ptr->num_trans; ++i)
1164 {
1165 if (png_ptr->trans_alpha[i] == 255)
1166 continue;
1167 else if (png_ptr->trans_alpha[i] == 0)
1168 input_has_transparency = 1;
1169 else
1170 {
1171 input_has_transparency = 1;
1172 input_has_alpha = 1;
1173 break;
1174 }
1175 }
1176 }
1177
1178 /* If no alpha we can optimize. */
1179 if (input_has_alpha == 0)
1180 {
1181 /* Any alpha means background and associative alpha processing is
1182 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1183 * and ENCODE_ALPHA are irrelevant.
1184 */
1185 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1186 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1187
1188 if (input_has_transparency == 0)
1189 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1190 }
1191
1192 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1193 /* png_set_background handling - deals with the complexity of whether the
1194 * background color is in the file format or the screen format in the case
1195 * where an 'expand' will happen.
1196 */
1197
1198 /* The following code cannot be entered in the alpha pre-multiplication case
1199 * because PNG_BACKGROUND_EXPAND is cancelled below.
1200 */
1201 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1202 (png_ptr->transformations & PNG_EXPAND) != 0)
1203 {
1204 {
1205 png_ptr->background.red =
1206 png_ptr->palette[png_ptr->background.index].red;
1207 png_ptr->background.green =
1208 png_ptr->palette[png_ptr->background.index].green;
1209 png_ptr->background.blue =
1210 png_ptr->palette[png_ptr->background.index].blue;
1211
1212 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1213 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
1214 {
1215 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1216 {
1217 /* Invert the alpha channel (in tRNS) unless the pixels are
1218 * going to be expanded, in which case leave it for later
1219 */
1220 int i, istop = png_ptr->num_trans;
1221
1222 for (i = 0; i < istop; i++)
1223 png_ptr->trans_alpha[i] =
1224 (png_byte)(255 - png_ptr->trans_alpha[i]);
1225 }
1226 }
1227 #endif /* READ_INVERT_ALPHA */
1228 }
1229 } /* background expand and (therefore) no alpha association. */
1230 #endif /* READ_EXPAND && READ_BACKGROUND */
1231 }
1232
1233 static void /* PRIVATE */
1234 png_init_rgb_transformations(png_structrp png_ptr)
1235 {
1236 /* Added to libpng-1.5.4: check the color type to determine whether there
1237 * is any alpha or transparency in the image and simply cancel the
1238 * background and alpha mode stuff if there isn't.
1239 */
1240 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
1241 int input_has_transparency = png_ptr->num_trans > 0;
1242
1243 /* If no alpha we can optimize. */
1244 if (input_has_alpha == 0)
1245 {
1246 /* Any alpha means background and associative alpha processing is
1247 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1248 * and ENCODE_ALPHA are irrelevant.
1249 */
1250 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1251 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1252 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1253 # endif
1254
1255 if (input_has_transparency == 0)
1256 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1257 }
1258
1259 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1260 /* png_set_background handling - deals with the complexity of whether the
1261 * background color is in the file format or the screen format in the case
1262 * where an 'expand' will happen.
1263 */
1264
1265 /* The following code cannot be entered in the alpha pre-multiplication case
1266 * because PNG_BACKGROUND_EXPAND is cancelled below.
1267 */
1268 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1269 (png_ptr->transformations & PNG_EXPAND) != 0 &&
1270 (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1271 /* i.e., GRAY or GRAY_ALPHA */
1272 {
1273 {
1274 /* Expand background and tRNS chunks */
1275 int gray = png_ptr->background.gray;
1276 int trans_gray = png_ptr->trans_color.gray;
1277
1278 switch (png_ptr->bit_depth)
1279 {
1280 case 1:
1281 gray *= 0xff;
1282 trans_gray *= 0xff;
1283 break;
1284
1285 case 2:
1286 gray *= 0x55;
1287 trans_gray *= 0x55;
1288 break;
1289
1290 case 4:
1291 gray *= 0x11;
1292 trans_gray *= 0x11;
1293 break;
1294
1295 default:
1296
1297 case 8:
1298 /* FALLTHROUGH */ /* (Already 8 bits) */
1299
1300 case 16:
1301 /* Already a full 16 bits */
1302 break;
1303 }
1304
1305 png_ptr->background.red = png_ptr->background.green =
1306 png_ptr->background.blue = (png_uint_16)gray;
1307
1308 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1309 {
1310 png_ptr->trans_color.red = png_ptr->trans_color.green =
1311 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
1312 }
1313 }
1314 } /* background expand and (therefore) no alpha association. */
1315 #endif /* READ_EXPAND && READ_BACKGROUND */
1316 }
1317
1318 void /* PRIVATE */
1319 png_init_read_transformations(png_structrp png_ptr)
1320 {
1321 png_debug(1, "in png_init_read_transformations");
1322
1323 /* This internal function is called from png_read_start_row in pngrutil.c
1324 * and it is called before the 'rowbytes' calculation is done, so the code
1325 * in here can change or update the transformations flags.
1326 *
1327 * First do updates that do not depend on the details of the PNG image data
1328 * being processed.
1329 */
1330
1331 #ifdef PNG_READ_GAMMA_SUPPORTED
1332 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1333 * png_set_alpha_mode and this is another source for a default file gamma so
1334 * the test needs to be performed later - here. In addition prior to 1.5.4
1335 * the tests were repeated for the PALETTE color type here - this is no
1336 * longer necessary (and doesn't seem to have been necessary before.)
1337 */
1338 {
1339 /* The following temporary indicates if overall gamma correction is
1340 * required.
1341 */
1342 int gamma_correction = 0;
1343
1344 if (png_ptr->colorspace.gamma != 0) /* has been set */
1345 {
1346 if (png_ptr->screen_gamma != 0) /* screen set too */
1347 gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
1348 png_ptr->screen_gamma);
1349
1350 else
1351 /* Assume the output matches the input; a long time default behavior
1352 * of libpng, although the standard has nothing to say about this.
1353 */
1354 png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
1355 }
1356
1357 else if (png_ptr->screen_gamma != 0)
1358 /* The converse - assume the file matches the screen, note that this
1359 * perhaps undesirable default can (from 1.5.4) be changed by calling
1360 * png_set_alpha_mode (even if the alpha handling mode isn't required
1361 * or isn't changed from the default.)
1362 */
1363 png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
1364
1365 else /* neither are set */
1366 /* Just in case the following prevents any processing - file and screen
1367 * are both assumed to be linear and there is no way to introduce a
1368 * third gamma value other than png_set_background with 'UNIQUE', and,
1369 * prior to 1.5.4
1370 */
1371 png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
1372
1373 /* We have a gamma value now. */
1374 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
1375
1376 /* Now turn the gamma transformation on or off as appropriate. Notice
1377 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1378 * composition may independently cause gamma correction because it needs
1379 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1380 * hasn't been specified.) In any case this flag may get turned off in
1381 * the code immediately below if the transform can be handled outside the
1382 * row loop.
1383 */
1384 if (gamma_correction != 0)
1385 png_ptr->transformations |= PNG_GAMMA;
1386
1387 else
1388 png_ptr->transformations &= ~PNG_GAMMA;
1389 }
1390 #endif
1391
1392 /* Certain transformations have the effect of preventing other
1393 * transformations that happen afterward in png_do_read_transformations;
1394 * resolve the interdependencies here. From the code of
1395 * png_do_read_transformations the order is:
1396 *
1397 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1398 * 2) PNG_STRIP_ALPHA (if no compose)
1399 * 3) PNG_RGB_TO_GRAY
1400 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1401 * 5) PNG_COMPOSE
1402 * 6) PNG_GAMMA
1403 * 7) PNG_STRIP_ALPHA (if compose)
1404 * 8) PNG_ENCODE_ALPHA
1405 * 9) PNG_SCALE_16_TO_8
1406 * 10) PNG_16_TO_8
1407 * 11) PNG_QUANTIZE (converts to palette)
1408 * 12) PNG_EXPAND_16
1409 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1410 * 14) PNG_INVERT_MONO
1411 * 15) PNG_INVERT_ALPHA
1412 * 16) PNG_SHIFT
1413 * 17) PNG_PACK
1414 * 18) PNG_BGR
1415 * 19) PNG_PACKSWAP
1416 * 20) PNG_FILLER (includes PNG_ADD_ALPHA)
1417 * 21) PNG_SWAP_ALPHA
1418 * 22) PNG_SWAP_BYTES
1419 * 23) PNG_USER_TRANSFORM [must be last]
1420 */
1421 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1422 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
1423 (png_ptr->transformations & PNG_COMPOSE) == 0)
1424 {
1425 /* Stripping the alpha channel happens immediately after the 'expand'
1426 * transformations, before all other transformation, so it cancels out
1427 * the alpha handling. It has the side effect negating the effect of
1428 * PNG_EXPAND_tRNS too:
1429 */
1430 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
1431 PNG_EXPAND_tRNS);
1432 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1433
1434 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1435 * so transparency information would remain just so long as it wasn't
1436 * expanded. This produces unexpected API changes if the set of things
1437 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1438 * documentation - which says ask for what you want, accept what you
1439 * get.) This makes the behavior consistent from 1.5.4:
1440 */
1441 png_ptr->num_trans = 0;
1442 }
1443 #endif /* STRIP_ALPHA supported, no COMPOSE */
1444
1445 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1446 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1447 * settings will have no effect.
1448 */
1449 if (png_gamma_significant(png_ptr->screen_gamma) == 0)
1450 {
1451 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1452 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1453 }
1454 #endif
1455
1456 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1457 /* Make sure the coefficients for the rgb to gray conversion are set
1458 * appropriately.
1459 */
1460 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1461 png_colorspace_set_rgb_coefficients(png_ptr);
1462 #endif
1463
1464 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1465 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1466 /* Detect gray background and attempt to enable optimization for
1467 * gray --> RGB case.
1468 *
1469 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1470 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1471 * background color might actually be gray yet not be flagged as such.
1472 * This is not a problem for the current code, which uses
1473 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1474 * png_do_gray_to_rgb() transformation.
1475 *
1476 * TODO: this code needs to be revised to avoid the complexity and
1477 * interdependencies. The color type of the background should be recorded in
1478 * png_set_background, along with the bit depth, then the code has a record
1479 * of exactly what color space the background is currently in.
1480 */
1481 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0)
1482 {
1483 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1484 * the file was grayscale the background value is gray.
1485 */
1486 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1487 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1488 }
1489
1490 else if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1491 {
1492 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1493 * so the color is in the color space of the output or png_set_alpha_mode
1494 * was called and the color is black. Ignore RGB_TO_GRAY because that
1495 * happens before GRAY_TO_RGB.
1496 */
1497 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
1498 {
1499 if (png_ptr->background.red == png_ptr->background.green &&
1500 png_ptr->background.red == png_ptr->background.blue)
1501 {
1502 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1503 png_ptr->background.gray = png_ptr->background.red;
1504 }
1505 }
1506 }
1507 #endif /* READ_EXPAND && READ_BACKGROUND */
1508 #endif /* READ_GRAY_TO_RGB */
1509
1510 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1511 * can be performed directly on the palette, and some (such as rgb to gray)
1512 * can be optimized inside the palette. This is particularly true of the
1513 * composite (background and alpha) stuff, which can be pretty much all done
1514 * in the palette even if the result is expanded to RGB or gray afterward.
1515 *
1516 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1517 * earlier and the palette stuff is actually handled on the first row. This
1518 * leads to the reported bug that the palette returned by png_get_PLTE is not
1519 * updated.
1520 */
1521 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1522 png_init_palette_transformations(png_ptr);
1523
1524 else
1525 png_init_rgb_transformations(png_ptr);
1526
1527 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1528 defined(PNG_READ_EXPAND_16_SUPPORTED)
1529 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
1530 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1531 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1532 png_ptr->bit_depth != 16)
1533 {
1534 /* TODO: fix this. Because the expand_16 operation is after the compose
1535 * handling the background color must be 8, not 16, bits deep, but the
1536 * application will supply a 16-bit value so reduce it here.
1537 *
1538 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1539 * present, so that case is ok (until do_expand_16 is moved.)
1540 *
1541 * NOTE: this discards the low 16 bits of the user supplied background
1542 * color, but until expand_16 works properly there is no choice!
1543 */
1544 # define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
1545 CHOP(png_ptr->background.red);
1546 CHOP(png_ptr->background.green);
1547 CHOP(png_ptr->background.blue);
1548 CHOP(png_ptr->background.gray);
1549 # undef CHOP
1550 }
1551 #endif /* READ_BACKGROUND && READ_EXPAND_16 */
1552
1553 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1554 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1555 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1556 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 &&
1557 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1558 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1559 png_ptr->bit_depth == 16)
1560 {
1561 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1562 * component this will also happen after PNG_COMPOSE and so the background
1563 * color must be pre-expanded here.
1564 *
1565 * TODO: fix this too.
1566 */
1567 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
1568 png_ptr->background.green =
1569 (png_uint_16)(png_ptr->background.green * 257);
1570 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
1571 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
1572 }
1573 #endif
1574
1575 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1576 * background support (see the comments in scripts/pnglibconf.dfa), this
1577 * allows pre-multiplication of the alpha channel to be implemented as
1578 * compositing on black. This is probably sub-optimal and has been done in
1579 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1580 * implement the new API quickly, without lots of internal changes.)
1581 */
1582
1583 #ifdef PNG_READ_GAMMA_SUPPORTED
1584 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1585 /* Includes ALPHA_MODE */
1586 png_ptr->background_1 = png_ptr->background;
1587 # endif
1588
1589 /* This needs to change - in the palette image case a whole set of tables are
1590 * built when it would be quicker to just calculate the correct value for
1591 * each palette entry directly. Also, the test is too tricky - why check
1592 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1593 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1594 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1595 * the gamma tables will not be built even if composition is required on a
1596 * gamma encoded value.
1597 *
1598 * In 1.5.4 this is addressed below by an additional check on the individual
1599 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1600 * tables.
1601 */
1602 if ((png_ptr->transformations & PNG_GAMMA) != 0 ||
1603 ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 &&
1604 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1605 png_gamma_significant(png_ptr->screen_gamma) != 0)) ||
1606 ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1607 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1608 png_gamma_significant(png_ptr->screen_gamma) != 0
1609 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1610 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE &&
1611 png_gamma_significant(png_ptr->background_gamma) != 0)
1612 # endif
1613 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
1614 png_gamma_significant(png_ptr->screen_gamma) != 0))
1615 {
1616 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
1617
1618 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1619 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1620 {
1621 /* Issue a warning about this combination: because RGB_TO_GRAY is
1622 * optimized to do the gamma transform if present yet do_background has
1623 * to do the same thing if both options are set a
1624 * double-gamma-correction happens. This is true in all versions of
1625 * libpng to date.
1626 */
1627 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1628 png_warning(png_ptr,
1629 "libpng does not support gamma+background+rgb_to_gray");
1630
1631 if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
1632 {
1633 /* We don't get to here unless there is a tRNS chunk with non-opaque
1634 * entries - see the checking code at the start of this function.
1635 */
1636 png_color back, back_1;
1637 png_colorp palette = png_ptr->palette;
1638 int num_palette = png_ptr->num_palette;
1639 int i;
1640 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
1641 {
1642
1643 back.red = png_ptr->gamma_table[png_ptr->background.red];
1644 back.green = png_ptr->gamma_table[png_ptr->background.green];
1645 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
1646
1647 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
1648 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
1649 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
1650 }
1651 else
1652 {
1653 png_fixed_point g, gs;
1654
1655 switch (png_ptr->background_gamma_type)
1656 {
1657 case PNG_BACKGROUND_GAMMA_SCREEN:
1658 g = (png_ptr->screen_gamma);
1659 gs = PNG_FP_1;
1660 break;
1661
1662 case PNG_BACKGROUND_GAMMA_FILE:
1663 g = png_reciprocal(png_ptr->colorspace.gamma);
1664 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1665 png_ptr->screen_gamma);
1666 break;
1667
1668 case PNG_BACKGROUND_GAMMA_UNIQUE:
1669 g = png_reciprocal(png_ptr->background_gamma);
1670 gs = png_reciprocal2(png_ptr->background_gamma,
1671 png_ptr->screen_gamma);
1672 break;
1673 default:
1674 g = PNG_FP_1; /* back_1 */
1675 gs = PNG_FP_1; /* back */
1676 break;
1677 }
1678
1679 if (png_gamma_significant(gs) != 0)
1680 {
1681 back.red = png_gamma_8bit_correct(png_ptr->background.red,
1682 gs);
1683 back.green = png_gamma_8bit_correct(png_ptr->background.green,
1684 gs);
1685 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1686 gs);
1687 }
1688
1689 else
1690 {
1691 back.red = (png_byte)png_ptr->background.red;
1692 back.green = (png_byte)png_ptr->background.green;
1693 back.blue = (png_byte)png_ptr->background.blue;
1694 }
1695
1696 if (png_gamma_significant(g) != 0)
1697 {
1698 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
1699 g);
1700 back_1.green = png_gamma_8bit_correct(
1701 png_ptr->background.green, g);
1702 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1703 g);
1704 }
1705
1706 else
1707 {
1708 back_1.red = (png_byte)png_ptr->background.red;
1709 back_1.green = (png_byte)png_ptr->background.green;
1710 back_1.blue = (png_byte)png_ptr->background.blue;
1711 }
1712 }
1713
1714 for (i = 0; i < num_palette; i++)
1715 {
1716 if (i < (int)png_ptr->num_trans &&
1717 png_ptr->trans_alpha[i] != 0xff)
1718 {
1719 if (png_ptr->trans_alpha[i] == 0)
1720 {
1721 palette[i] = back;
1722 }
1723 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1724 {
1725 png_byte v, w;
1726
1727 v = png_ptr->gamma_to_1[palette[i].red];
1728 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
1729 palette[i].red = png_ptr->gamma_from_1[w];
1730
1731 v = png_ptr->gamma_to_1[palette[i].green];
1732 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
1733 palette[i].green = png_ptr->gamma_from_1[w];
1734
1735 v = png_ptr->gamma_to_1[palette[i].blue];
1736 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
1737 palette[i].blue = png_ptr->gamma_from_1[w];
1738 }
1739 }
1740 else
1741 {
1742 palette[i].red = png_ptr->gamma_table[palette[i].red];
1743 palette[i].green = png_ptr->gamma_table[palette[i].green];
1744 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1745 }
1746 }
1747
1748 /* Prevent the transformations being done again.
1749 *
1750 * NOTE: this is highly dubious; it removes the transformations in
1751 * place. This seems inconsistent with the general treatment of the
1752 * transformations elsewhere.
1753 */
1754 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
1755 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1756
1757 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1758 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1759 {
1760 int gs_sig, g_sig;
1761 png_fixed_point g = PNG_FP_1; /* Correction to linear */
1762 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
1763
1764 switch (png_ptr->background_gamma_type)
1765 {
1766 case PNG_BACKGROUND_GAMMA_SCREEN:
1767 g = png_ptr->screen_gamma;
1768 /* gs = PNG_FP_1; */
1769 break;
1770
1771 case PNG_BACKGROUND_GAMMA_FILE:
1772 g = png_reciprocal(png_ptr->colorspace.gamma);
1773 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1774 png_ptr->screen_gamma);
1775 break;
1776
1777 case PNG_BACKGROUND_GAMMA_UNIQUE:
1778 g = png_reciprocal(png_ptr->background_gamma);
1779 gs = png_reciprocal2(png_ptr->background_gamma,
1780 png_ptr->screen_gamma);
1781 break;
1782
1783 default:
1784 png_error(png_ptr, "invalid background gamma type");
1785 }
1786
1787 g_sig = png_gamma_significant(g);
1788 gs_sig = png_gamma_significant(gs);
1789
1790 if (g_sig != 0)
1791 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
1792 png_ptr->background.gray, g);
1793
1794 if (gs_sig != 0)
1795 png_ptr->background.gray = png_gamma_correct(png_ptr,
1796 png_ptr->background.gray, gs);
1797
1798 if ((png_ptr->background.red != png_ptr->background.green) ||
1799 (png_ptr->background.red != png_ptr->background.blue) ||
1800 (png_ptr->background.red != png_ptr->background.gray))
1801 {
1802 /* RGB or RGBA with color background */
1803 if (g_sig != 0)
1804 {
1805 png_ptr->background_1.red = png_gamma_correct(png_ptr,
1806 png_ptr->background.red, g);
1807
1808 png_ptr->background_1.green = png_gamma_correct(png_ptr,
1809 png_ptr->background.green, g);
1810
1811 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
1812 png_ptr->background.blue, g);
1813 }
1814
1815 if (gs_sig != 0)
1816 {
1817 png_ptr->background.red = png_gamma_correct(png_ptr,
1818 png_ptr->background.red, gs);
1819
1820 png_ptr->background.green = png_gamma_correct(png_ptr,
1821 png_ptr->background.green, gs);
1822
1823 png_ptr->background.blue = png_gamma_correct(png_ptr,
1824 png_ptr->background.blue, gs);
1825 }
1826 }
1827
1828 else
1829 {
1830 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1831 png_ptr->background_1.red = png_ptr->background_1.green
1832 = png_ptr->background_1.blue = png_ptr->background_1.gray;
1833
1834 png_ptr->background.red = png_ptr->background.green
1835 = png_ptr->background.blue = png_ptr->background.gray;
1836 }
1837
1838 /* The background is now in screen gamma: */
1839 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
1840 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1841 }/* png_ptr->transformations & PNG_BACKGROUND */
1842
1843 else
1844 /* Transformation does not include PNG_BACKGROUND */
1845 #endif /* READ_BACKGROUND */
1846 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
1847 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1848 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1849 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
1850 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
1851 #endif
1852 )
1853 {
1854 png_colorp palette = png_ptr->palette;
1855 int num_palette = png_ptr->num_palette;
1856 int i;
1857
1858 /* NOTE: there are other transformations that should probably be in
1859 * here too.
1860 */
1861 for (i = 0; i < num_palette; i++)
1862 {
1863 palette[i].red = png_ptr->gamma_table[palette[i].red];
1864 palette[i].green = png_ptr->gamma_table[palette[i].green];
1865 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1866 }
1867
1868 /* Done the gamma correction. */
1869 png_ptr->transformations &= ~PNG_GAMMA;
1870 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1871 }
1872 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1873 else
1874 #endif
1875 #endif /* READ_GAMMA */
1876
1877 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1878 /* No GAMMA transformation (see the hanging else 4 lines above) */
1879 if ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1880 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1881 {
1882 int i;
1883 int istop = (int)png_ptr->num_trans;
1884 png_color back;
1885 png_colorp palette = png_ptr->palette;
1886
1887 back.red = (png_byte)png_ptr->background.red;
1888 back.green = (png_byte)png_ptr->background.green;
1889 back.blue = (png_byte)png_ptr->background.blue;
1890
1891 for (i = 0; i < istop; i++)
1892 {
1893 if (png_ptr->trans_alpha[i] == 0)
1894 {
1895 palette[i] = back;
1896 }
1897
1898 else if (png_ptr->trans_alpha[i] != 0xff)
1899 {
1900 /* The png_composite() macro is defined in png.h */
1901 png_composite(palette[i].red, palette[i].red,
1902 png_ptr->trans_alpha[i], back.red);
1903
1904 png_composite(palette[i].green, palette[i].green,
1905 png_ptr->trans_alpha[i], back.green);
1906
1907 png_composite(palette[i].blue, palette[i].blue,
1908 png_ptr->trans_alpha[i], back.blue);
1909 }
1910 }
1911
1912 png_ptr->transformations &= ~PNG_COMPOSE;
1913 }
1914 #endif /* READ_BACKGROUND */
1915
1916 #ifdef PNG_READ_SHIFT_SUPPORTED
1917 if ((png_ptr->transformations & PNG_SHIFT) != 0 &&
1918 (png_ptr->transformations & PNG_EXPAND) == 0 &&
1919 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1920 {
1921 int i;
1922 int istop = png_ptr->num_palette;
1923 int shift = 8 - png_ptr->sig_bit.red;
1924
1925 png_ptr->transformations &= ~PNG_SHIFT;
1926
1927 /* significant bits can be in the range 1 to 7 for a meaningful result, if
1928 * the number of significant bits is 0 then no shift is done (this is an
1929 * error condition which is silently ignored.)
1930 */
1931 if (shift > 0 && shift < 8)
1932 for (i=0; i<istop; ++i)
1933 {
1934 int component = png_ptr->palette[i].red;
1935
1936 component >>= shift;
1937 png_ptr->palette[i].red = (png_byte)component;
1938 }
1939
1940 shift = 8 - png_ptr->sig_bit.green;
1941 if (shift > 0 && shift < 8)
1942 for (i=0; i<istop; ++i)
1943 {
1944 int component = png_ptr->palette[i].green;
1945
1946 component >>= shift;
1947 png_ptr->palette[i].green = (png_byte)component;
1948 }
1949
1950 shift = 8 - png_ptr->sig_bit.blue;
1951 if (shift > 0 && shift < 8)
1952 for (i=0; i<istop; ++i)
1953 {
1954 int component = png_ptr->palette[i].blue;
1955
1956 component >>= shift;
1957 png_ptr->palette[i].blue = (png_byte)component;
1958 }
1959 }
1960 #endif /* READ_SHIFT */
1961 }
1962
1963 /* Modify the info structure to reflect the transformations. The
1964 * info should be updated so a PNG file could be written with it,
1965 * assuming the transformations result in valid PNG data.
1966 */
1967 void /* PRIVATE */
1968 png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
1969 {
1970 png_debug(1, "in png_read_transform_info");
1971
1972 #ifdef PNG_READ_EXPAND_SUPPORTED
1973 if ((png_ptr->transformations & PNG_EXPAND) != 0)
1974 {
1975 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1976 {
1977 /* This check must match what actually happens in
1978 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1979 * it is all opaque we must do the same (at present it does not.)
1980 */
1981 if (png_ptr->num_trans > 0)
1982 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
1983
1984 else
1985 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
1986
1987 info_ptr->bit_depth = 8;
1988 info_ptr->num_trans = 0;
1989
1990 if (png_ptr->palette == NULL)
1991 png_error (png_ptr, "Palette is NULL in indexed image");
1992 }
1993 else
1994 {
1995 if (png_ptr->num_trans != 0)
1996 {
1997 if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
1998 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
1999 }
2000 if (info_ptr->bit_depth < 8)
2001 info_ptr->bit_depth = 8;
2002
2003 info_ptr->num_trans = 0;
2004 }
2005 }
2006 #endif
2007
2008 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
2009 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
2010 /* The following is almost certainly wrong unless the background value is in
2011 * the screen space!
2012 */
2013 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
2014 info_ptr->background = png_ptr->background;
2015 #endif
2016
2017 #ifdef PNG_READ_GAMMA_SUPPORTED
2018 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
2019 * however it seems that the code in png_init_read_transformations, which has
2020 * been called before this from png_read_update_info->png_read_start_row
2021 * sometimes does the gamma transform and cancels the flag.
2022 *
2023 * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
2024 * the screen_gamma value. The following probably results in weirdness if
2025 * the info_ptr is used by the app after the rows have been read.
2026 */
2027 info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
2028 #endif
2029
2030 if (info_ptr->bit_depth == 16)
2031 {
2032 # ifdef PNG_READ_16BIT_SUPPORTED
2033 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2034 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
2035 info_ptr->bit_depth = 8;
2036 # endif
2037
2038 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2039 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
2040 info_ptr->bit_depth = 8;
2041 # endif
2042
2043 # else
2044 /* No 16-bit support: force chopping 16-bit input down to 8, in this case
2045 * the app program can chose if both APIs are available by setting the
2046 * correct scaling to use.
2047 */
2048 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2049 /* For compatibility with previous versions use the strip method by
2050 * default. This code works because if PNG_SCALE_16_TO_8 is already
2051 * set the code below will do that in preference to the chop.
2052 */
2053 png_ptr->transformations |= PNG_16_TO_8;
2054 info_ptr->bit_depth = 8;
2055 # else
2056
2057 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2058 png_ptr->transformations |= PNG_SCALE_16_TO_8;
2059 info_ptr->bit_depth = 8;
2060 # else
2061
2062 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
2063 # endif
2064 # endif
2065 #endif /* !READ_16BIT */
2066 }
2067
2068 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2069 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
2070 info_ptr->color_type = (png_byte)(info_ptr->color_type |
2071 PNG_COLOR_MASK_COLOR);
2072 #endif
2073
2074 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2075 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
2076 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2077 ~PNG_COLOR_MASK_COLOR);
2078 #endif
2079
2080 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2081 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
2082 {
2083 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2084 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
2085 png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8)
2086 {
2087 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
2088 }
2089 }
2090 #endif
2091
2092 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2093 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
2094 info_ptr->bit_depth == 8 &&
2095 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
2096 {
2097 info_ptr->bit_depth = 16;
2098 }
2099 #endif
2100
2101 #ifdef PNG_READ_PACK_SUPPORTED
2102 if ((png_ptr->transformations & PNG_PACK) != 0 &&
2103 (info_ptr->bit_depth < 8))
2104 info_ptr->bit_depth = 8;
2105 #endif
2106
2107 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
2108 info_ptr->channels = 1;
2109
2110 else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
2111 info_ptr->channels = 3;
2112
2113 else
2114 info_ptr->channels = 1;
2115
2116 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2117 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0)
2118 {
2119 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2120 ~PNG_COLOR_MASK_ALPHA);
2121 info_ptr->num_trans = 0;
2122 }
2123 #endif
2124
2125 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
2126 info_ptr->channels++;
2127
2128 #ifdef PNG_READ_FILLER_SUPPORTED
2129 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2130 if ((png_ptr->transformations & PNG_FILLER) != 0 &&
2131 (info_ptr->color_type == PNG_COLOR_TYPE_RGB ||
2132 info_ptr->color_type == PNG_COLOR_TYPE_GRAY))
2133 {
2134 info_ptr->channels++;
2135 /* If adding a true alpha channel not just filler */
2136 if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0)
2137 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
2138 }
2139 #endif
2140
2141 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2142 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2143 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
2144 {
2145 if (png_ptr->user_transform_depth != 0)
2146 info_ptr->bit_depth = png_ptr->user_transform_depth;
2147
2148 if (png_ptr->user_transform_channels != 0)
2149 info_ptr->channels = png_ptr->user_transform_channels;
2150 }
2151 #endif
2152
2153 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
2154 info_ptr->bit_depth);
2155
2156 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
2157
2158 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2159 * check in png_rowbytes that the user buffer won't get overwritten. Note
2160 * that the field is not always set - if png_read_update_info isn't called
2161 * the application has to either not do any transforms or get the calculation
2162 * right itself.
2163 */
2164 png_ptr->info_rowbytes = info_ptr->rowbytes;
2165
2166 #ifndef PNG_READ_EXPAND_SUPPORTED
2167 if (png_ptr != NULL)
2168 return;
2169 #endif
2170 }
2171
2172 #ifdef PNG_READ_PACK_SUPPORTED
2173 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2174 * without changing the actual values. Thus, if you had a row with
2175 * a bit depth of 1, you would end up with bytes that only contained
2176 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2177 * png_do_shift() after this.
2178 */
2179 static void
2180 png_do_unpack(png_row_infop row_info, png_bytep row)
2181 {
2182 png_debug(1, "in png_do_unpack");
2183
2184 if (row_info->bit_depth < 8)
2185 {
2186 png_uint_32 i;
2187 png_uint_32 row_width=row_info->width;
2188
2189 switch (row_info->bit_depth)
2190 {
2191 case 1:
2192 {
2193 png_bytep sp = row + (size_t)((row_width - 1) >> 3);
2194 png_bytep dp = row + (size_t)row_width - 1;
2195 png_uint_32 shift = 7U - ((row_width + 7U) & 0x07);
2196 for (i = 0; i < row_width; i++)
2197 {
2198 *dp = (png_byte)((*sp >> shift) & 0x01);
2199
2200 if (shift == 7)
2201 {
2202 shift = 0;
2203 sp--;
2204 }
2205
2206 else
2207 shift++;
2208
2209 dp--;
2210 }
2211 break;
2212 }
2213
2214 case 2:
2215 {
2216
2217 png_bytep sp = row + (size_t)((row_width - 1) >> 2);
2218 png_bytep dp = row + (size_t)row_width - 1;
2219 png_uint_32 shift = ((3U - ((row_width + 3U) & 0x03)) << 1);
2220 for (i = 0; i < row_width; i++)
2221 {
2222 *dp = (png_byte)((*sp >> shift) & 0x03);
2223
2224 if (shift == 6)
2225 {
2226 shift = 0;
2227 sp--;
2228 }
2229
2230 else
2231 shift += 2;
2232
2233 dp--;
2234 }
2235 break;
2236 }
2237
2238 case 4:
2239 {
2240 png_bytep sp = row + (size_t)((row_width - 1) >> 1);
2241 png_bytep dp = row + (size_t)row_width - 1;
2242 png_uint_32 shift = ((1U - ((row_width + 1U) & 0x01)) << 2);
2243 for (i = 0; i < row_width; i++)
2244 {
2245 *dp = (png_byte)((*sp >> shift) & 0x0f);
2246
2247 if (shift == 4)
2248 {
2249 shift = 0;
2250 sp--;
2251 }
2252
2253 else
2254 shift = 4;
2255
2256 dp--;
2257 }
2258 break;
2259 }
2260
2261 default:
2262 break;
2263 }
2264 row_info->bit_depth = 8;
2265 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2266 row_info->rowbytes = row_width * row_info->channels;
2267 }
2268 }
2269 #endif
2270
2271 #ifdef PNG_READ_SHIFT_SUPPORTED
2272 /* Reverse the effects of png_do_shift. This routine merely shifts the
2273 * pixels back to their significant bits values. Thus, if you have
2274 * a row of bit depth 8, but only 5 are significant, this will shift
2275 * the values back to 0 through 31.
2276 */
2277 static void
2278 png_do_unshift(png_row_infop row_info, png_bytep row,
2279 png_const_color_8p sig_bits)
2280 {
2281 int color_type;
2282
2283 png_debug(1, "in png_do_unshift");
2284
2285 /* The palette case has already been handled in the _init routine. */
2286 color_type = row_info->color_type;
2287
2288 if (color_type != PNG_COLOR_TYPE_PALETTE)
2289 {
2290 int shift[4];
2291 int channels = 0;
2292 int bit_depth = row_info->bit_depth;
2293
2294 if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
2295 {
2296 shift[channels++] = bit_depth - sig_bits->red;
2297 shift[channels++] = bit_depth - sig_bits->green;
2298 shift[channels++] = bit_depth - sig_bits->blue;
2299 }
2300
2301 else
2302 {
2303 shift[channels++] = bit_depth - sig_bits->gray;
2304 }
2305
2306 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
2307 {
2308 shift[channels++] = bit_depth - sig_bits->alpha;
2309 }
2310
2311 {
2312 int c, have_shift;
2313
2314 for (c = have_shift = 0; c < channels; ++c)
2315 {
2316 /* A shift of more than the bit depth is an error condition but it
2317 * gets ignored here.
2318 */
2319 if (shift[c] <= 0 || shift[c] >= bit_depth)
2320 shift[c] = 0;
2321
2322 else
2323 have_shift = 1;
2324 }
2325
2326 if (have_shift == 0)
2327 return;
2328 }
2329
2330 switch (bit_depth)
2331 {
2332 default:
2333 /* Must be 1bpp gray: should not be here! */
2334 /* NOTREACHED */
2335 break;
2336
2337 case 2:
2338 /* Must be 2bpp gray */
2339 /* assert(channels == 1 && shift[0] == 1) */
2340 {
2341 png_bytep bp = row;
2342 png_bytep bp_end = bp + row_info->rowbytes;
2343
2344 while (bp < bp_end)
2345 {
2346 int b = (*bp >> 1) & 0x55;
2347 *bp++ = (png_byte)b;
2348 }
2349 break;
2350 }
2351
2352 case 4:
2353 /* Must be 4bpp gray */
2354 /* assert(channels == 1) */
2355 {
2356 png_bytep bp = row;
2357 png_bytep bp_end = bp + row_info->rowbytes;
2358 int gray_shift = shift[0];
2359 int mask = 0xf >> gray_shift;
2360
2361 mask |= mask << 4;
2362
2363 while (bp < bp_end)
2364 {
2365 int b = (*bp >> gray_shift) & mask;
2366 *bp++ = (png_byte)b;
2367 }
2368 break;
2369 }
2370
2371 case 8:
2372 /* Single byte components, G, GA, RGB, RGBA */
2373 {
2374 png_bytep bp = row;
2375 png_bytep bp_end = bp + row_info->rowbytes;
2376 int channel = 0;
2377
2378 while (bp < bp_end)
2379 {
2380 int b = *bp >> shift[channel];
2381 if (++channel >= channels)
2382 channel = 0;
2383 *bp++ = (png_byte)b;
2384 }
2385 break;
2386 }
2387
2388 #ifdef PNG_READ_16BIT_SUPPORTED
2389 case 16:
2390 /* Double byte components, G, GA, RGB, RGBA */
2391 {
2392 png_bytep bp = row;
2393 png_bytep bp_end = bp + row_info->rowbytes;
2394 int channel = 0;
2395
2396 while (bp < bp_end)
2397 {
2398 int value = (bp[0] << 8) + bp[1];
2399
2400 value >>= shift[channel];
2401 if (++channel >= channels)
2402 channel = 0;
2403 *bp++ = (png_byte)(value >> 8);
2404 *bp++ = (png_byte)value;
2405 }
2406 break;
2407 }
2408 #endif
2409 }
2410 }
2411 }
2412 #endif
2413
2414 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2415 /* Scale rows of bit depth 16 down to 8 accurately */
2416 static void
2417 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
2418 {
2419 png_debug(1, "in png_do_scale_16_to_8");
2420
2421 if (row_info->bit_depth == 16)
2422 {
2423 png_bytep sp = row; /* source */
2424 png_bytep dp = row; /* destination */
2425 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2426
2427 while (sp < ep)
2428 {
2429 /* The input is an array of 16-bit components, these must be scaled to
2430 * 8 bits each. For a 16-bit value V the required value (from the PNG
2431 * specification) is:
2432 *
2433 * (V * 255) / 65535
2434 *
2435 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2436 *
2437 * Represent V as the two byte value vhi.vlo. Make a guess that the
2438 * result is the top byte of V, vhi, then the correction to this value
2439 * is:
2440 *
2441 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2442 * = floor(((vlo-vhi) + 128.5) / 257)
2443 *
2444 * This can be approximated using integer arithmetic (and a signed
2445 * shift):
2446 *
2447 * error = (vlo-vhi+128) >> 8;
2448 *
2449 * The approximate differs from the exact answer only when (vlo-vhi) is
2450 * 128; it then gives a correction of +1 when the exact correction is
2451 * 0. This gives 128 errors. The exact answer (correct for all 16-bit
2452 * input values) is:
2453 *
2454 * error = (vlo-vhi+128)*65535 >> 24;
2455 *
2456 * An alternative arithmetic calculation which also gives no errors is:
2457 *
2458 * (V * 255 + 32895) >> 16
2459 */
2460
2461 png_int_32 tmp = *sp++; /* must be signed! */
2462 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
2463 *dp++ = (png_byte)tmp;
2464 }
2465
2466 row_info->bit_depth = 8;
2467 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2468 row_info->rowbytes = row_info->width * row_info->channels;
2469 }
2470 }
2471 #endif
2472
2473 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2474 static void
2475 /* Simply discard the low byte. This was the default behavior prior
2476 * to libpng-1.5.4.
2477 */
2478 png_do_chop(png_row_infop row_info, png_bytep row)
2479 {
2480 png_debug(1, "in png_do_chop");
2481
2482 if (row_info->bit_depth == 16)
2483 {
2484 png_bytep sp = row; /* source */
2485 png_bytep dp = row; /* destination */
2486 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2487
2488 while (sp < ep)
2489 {
2490 *dp++ = *sp;
2491 sp += 2; /* skip low byte */
2492 }
2493
2494 row_info->bit_depth = 8;
2495 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2496 row_info->rowbytes = row_info->width * row_info->channels;
2497 }
2498 }
2499 #endif
2500
2501 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2502 static void
2503 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
2504 {
2505 png_uint_32 row_width = row_info->width;
2506
2507 png_debug(1, "in png_do_read_swap_alpha");
2508
2509 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2510 {
2511 /* This converts from RGBA to ARGB */
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) = *(--sp);
2524 *(--dp) = *(--sp);
2525 *(--dp) = save;
2526 }
2527 }
2528
2529 #ifdef PNG_READ_16BIT_SUPPORTED
2530 /* This converts from RRGGBBAA to AARRGGBB */
2531 else
2532 {
2533 png_bytep sp = row + row_info->rowbytes;
2534 png_bytep dp = sp;
2535 png_byte save[2];
2536 png_uint_32 i;
2537
2538 for (i = 0; i < row_width; i++)
2539 {
2540 save[0] = *(--sp);
2541 save[1] = *(--sp);
2542 *(--dp) = *(--sp);
2543 *(--dp) = *(--sp);
2544 *(--dp) = *(--sp);
2545 *(--dp) = *(--sp);
2546 *(--dp) = *(--sp);
2547 *(--dp) = *(--sp);
2548 *(--dp) = save[0];
2549 *(--dp) = save[1];
2550 }
2551 }
2552 #endif
2553 }
2554
2555 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2556 {
2557 /* This converts from GA to AG */
2558 if (row_info->bit_depth == 8)
2559 {
2560 png_bytep sp = row + row_info->rowbytes;
2561 png_bytep dp = sp;
2562 png_byte save;
2563 png_uint_32 i;
2564
2565 for (i = 0; i < row_width; i++)
2566 {
2567 save = *(--sp);
2568 *(--dp) = *(--sp);
2569 *(--dp) = save;
2570 }
2571 }
2572
2573 #ifdef PNG_READ_16BIT_SUPPORTED
2574 /* This converts from GGAA to AAGG */
2575 else
2576 {
2577 png_bytep sp = row + row_info->rowbytes;
2578 png_bytep dp = sp;
2579 png_byte save[2];
2580 png_uint_32 i;
2581
2582 for (i = 0; i < row_width; i++)
2583 {
2584 save[0] = *(--sp);
2585 save[1] = *(--sp);
2586 *(--dp) = *(--sp);
2587 *(--dp) = *(--sp);
2588 *(--dp) = save[0];
2589 *(--dp) = save[1];
2590 }
2591 }
2592 #endif
2593 }
2594 }
2595 #endif
2596
2597 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2598 static void
2599 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
2600 {
2601 png_uint_32 row_width;
2602 png_debug(1, "in png_do_read_invert_alpha");
2603
2604 row_width = row_info->width;
2605 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2606 {
2607 if (row_info->bit_depth == 8)
2608 {
2609 /* This inverts the alpha channel in RGBA */
2610 png_bytep sp = row + row_info->rowbytes;
2611 png_bytep dp = sp;
2612 png_uint_32 i;
2613
2614 for (i = 0; i < row_width; i++)
2615 {
2616 *(--dp) = (png_byte)(255 - *(--sp));
2617
2618 /* This does nothing:
2619 *(--dp) = *(--sp);
2620 *(--dp) = *(--sp);
2621 *(--dp) = *(--sp);
2622 We can replace it with:
2623 */
2624 sp-=3;
2625 dp=sp;
2626 }
2627 }
2628
2629 #ifdef PNG_READ_16BIT_SUPPORTED
2630 /* This inverts the alpha channel in RRGGBBAA */
2631 else
2632 {
2633 png_bytep sp = row + row_info->rowbytes;
2634 png_bytep dp = sp;
2635 png_uint_32 i;
2636
2637 for (i = 0; i < row_width; i++)
2638 {
2639 *(--dp) = (png_byte)(255 - *(--sp));
2640 *(--dp) = (png_byte)(255 - *(--sp));
2641
2642 /* This does nothing:
2643 *(--dp) = *(--sp);
2644 *(--dp) = *(--sp);
2645 *(--dp) = *(--sp);
2646 *(--dp) = *(--sp);
2647 *(--dp) = *(--sp);
2648 *(--dp) = *(--sp);
2649 We can replace it with:
2650 */
2651 sp-=6;
2652 dp=sp;
2653 }
2654 }
2655 #endif
2656 }
2657 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2658 {
2659 if (row_info->bit_depth == 8)
2660 {
2661 /* This inverts the alpha channel in GA */
2662 png_bytep sp = row + row_info->rowbytes;
2663 png_bytep dp = sp;
2664 png_uint_32 i;
2665
2666 for (i = 0; i < row_width; i++)
2667 {
2668 *(--dp) = (png_byte)(255 - *(--sp));
2669 *(--dp) = *(--sp);
2670 }
2671 }
2672
2673 #ifdef PNG_READ_16BIT_SUPPORTED
2674 else
2675 {
2676 /* This inverts the alpha channel in GGAA */
2677 png_bytep sp = row + row_info->rowbytes;
2678 png_bytep dp = sp;
2679 png_uint_32 i;
2680
2681 for (i = 0; i < row_width; i++)
2682 {
2683 *(--dp) = (png_byte)(255 - *(--sp));
2684 *(--dp) = (png_byte)(255 - *(--sp));
2685 /*
2686 *(--dp) = *(--sp);
2687 *(--dp) = *(--sp);
2688 */
2689 sp-=2;
2690 dp=sp;
2691 }
2692 }
2693 #endif
2694 }
2695 }
2696 #endif
2697
2698 #ifdef PNG_READ_FILLER_SUPPORTED
2699 /* Add filler channel if we have RGB color */
2700 static void
2701 png_do_read_filler(png_row_infop row_info, png_bytep row,
2702 png_uint_32 filler, png_uint_32 flags)
2703 {
2704 png_uint_32 i;
2705 png_uint_32 row_width = row_info->width;
2706
2707 #ifdef PNG_READ_16BIT_SUPPORTED
2708 png_byte hi_filler = (png_byte)(filler>>8);
2709 #endif
2710 png_byte lo_filler = (png_byte)filler;
2711
2712 png_debug(1, "in png_do_read_filler");
2713
2714 if (
2715 row_info->color_type == PNG_COLOR_TYPE_GRAY)
2716 {
2717 if (row_info->bit_depth == 8)
2718 {
2719 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2720 {
2721 /* This changes the data from G to GX */
2722 png_bytep sp = row + (size_t)row_width;
2723 png_bytep dp = sp + (size_t)row_width;
2724 for (i = 1; i < row_width; i++)
2725 {
2726 *(--dp) = lo_filler;
2727 *(--dp) = *(--sp);
2728 }
2729 *(--dp) = lo_filler;
2730 row_info->channels = 2;
2731 row_info->pixel_depth = 16;
2732 row_info->rowbytes = row_width * 2;
2733 }
2734
2735 else
2736 {
2737 /* This changes the data from G to XG */
2738 png_bytep sp = row + (size_t)row_width;
2739 png_bytep dp = sp + (size_t)row_width;
2740 for (i = 0; i < row_width; i++)
2741 {
2742 *(--dp) = *(--sp);
2743 *(--dp) = lo_filler;
2744 }
2745 row_info->channels = 2;
2746 row_info->pixel_depth = 16;
2747 row_info->rowbytes = row_width * 2;
2748 }
2749 }
2750
2751 #ifdef PNG_READ_16BIT_SUPPORTED
2752 else if (row_info->bit_depth == 16)
2753 {
2754 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2755 {
2756 /* This changes the data from GG to GGXX */
2757 png_bytep sp = row + (size_t)row_width * 2;
2758 png_bytep dp = sp + (size_t)row_width * 2;
2759 for (i = 1; i < row_width; i++)
2760 {
2761 *(--dp) = lo_filler;
2762 *(--dp) = hi_filler;
2763 *(--dp) = *(--sp);
2764 *(--dp) = *(--sp);
2765 }
2766 *(--dp) = lo_filler;
2767 *(--dp) = hi_filler;
2768 row_info->channels = 2;
2769 row_info->pixel_depth = 32;
2770 row_info->rowbytes = row_width * 4;
2771 }
2772
2773 else
2774 {
2775 /* This changes the data from GG to XXGG */
2776 png_bytep sp = row + (size_t)row_width * 2;
2777 png_bytep dp = sp + (size_t)row_width * 2;
2778 for (i = 0; i < row_width; i++)
2779 {
2780 *(--dp) = *(--sp);
2781 *(--dp) = *(--sp);
2782 *(--dp) = lo_filler;
2783 *(--dp) = hi_filler;
2784 }
2785 row_info->channels = 2;
2786 row_info->pixel_depth = 32;
2787 row_info->rowbytes = row_width * 4;
2788 }
2789 }
2790 #endif
2791 } /* COLOR_TYPE == GRAY */
2792 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
2793 {
2794 if (row_info->bit_depth == 8)
2795 {
2796 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2797 {
2798 /* This changes the data from RGB to RGBX */
2799 png_bytep sp = row + (size_t)row_width * 3;
2800 png_bytep dp = sp + (size_t)row_width;
2801 for (i = 1; i < row_width; i++)
2802 {
2803 *(--dp) = lo_filler;
2804 *(--dp) = *(--sp);
2805 *(--dp) = *(--sp);
2806 *(--dp) = *(--sp);
2807 }
2808 *(--dp) = lo_filler;
2809 row_info->channels = 4;
2810 row_info->pixel_depth = 32;
2811 row_info->rowbytes = row_width * 4;
2812 }
2813
2814 else
2815 {
2816 /* This changes the data from RGB to XRGB */
2817 png_bytep sp = row + (size_t)row_width * 3;
2818 png_bytep dp = sp + (size_t)row_width;
2819 for (i = 0; i < row_width; i++)
2820 {
2821 *(--dp) = *(--sp);
2822 *(--dp) = *(--sp);
2823 *(--dp) = *(--sp);
2824 *(--dp) = lo_filler;
2825 }
2826 row_info->channels = 4;
2827 row_info->pixel_depth = 32;
2828 row_info->rowbytes = row_width * 4;
2829 }
2830 }
2831
2832 #ifdef PNG_READ_16BIT_SUPPORTED
2833 else if (row_info->bit_depth == 16)
2834 {
2835 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2836 {
2837 /* This changes the data from RRGGBB to RRGGBBXX */
2838 png_bytep sp = row + (size_t)row_width * 6;
2839 png_bytep dp = sp + (size_t)row_width * 2;
2840 for (i = 1; i < row_width; i++)
2841 {
2842 *(--dp) = lo_filler;
2843 *(--dp) = hi_filler;
2844 *(--dp) = *(--sp);
2845 *(--dp) = *(--sp);
2846 *(--dp) = *(--sp);
2847 *(--dp) = *(--sp);
2848 *(--dp) = *(--sp);
2849 *(--dp) = *(--sp);
2850 }
2851 *(--dp) = lo_filler;
2852 *(--dp) = hi_filler;
2853 row_info->channels = 4;
2854 row_info->pixel_depth = 64;
2855 row_info->rowbytes = row_width * 8;
2856 }
2857
2858 else
2859 {
2860 /* This changes the data from RRGGBB to XXRRGGBB */
2861 png_bytep sp = row + (size_t)row_width * 6;
2862 png_bytep dp = sp + (size_t)row_width * 2;
2863 for (i = 0; i < row_width; i++)
2864 {
2865 *(--dp) = *(--sp);
2866 *(--dp) = *(--sp);
2867 *(--dp) = *(--sp);
2868 *(--dp) = *(--sp);
2869 *(--dp) = *(--sp);
2870 *(--dp) = *(--sp);
2871 *(--dp) = lo_filler;
2872 *(--dp) = hi_filler;
2873 }
2874
2875 row_info->channels = 4;
2876 row_info->pixel_depth = 64;
2877 row_info->rowbytes = row_width * 8;
2878 }
2879 }
2880 #endif
2881 } /* COLOR_TYPE == RGB */
2882 }
2883 #endif
2884
2885 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2886 /* Expand grayscale files to RGB, with or without alpha */
2887 static void
2888 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
2889 {
2890 png_uint_32 i;
2891 png_uint_32 row_width = row_info->width;
2892
2893 png_debug(1, "in png_do_gray_to_rgb");
2894
2895 if (row_info->bit_depth >= 8 &&
2896 (row_info->color_type & PNG_COLOR_MASK_COLOR) == 0)
2897 {
2898 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
2899 {
2900 if (row_info->bit_depth == 8)
2901 {
2902 /* This changes G to RGB */
2903 png_bytep sp = row + (size_t)row_width - 1;
2904 png_bytep dp = sp + (size_t)row_width * 2;
2905 for (i = 0; i < row_width; i++)
2906 {
2907 *(dp--) = *sp;
2908 *(dp--) = *sp;
2909 *(dp--) = *(sp--);
2910 }
2911 }
2912
2913 else
2914 {
2915 /* This changes GG to RRGGBB */
2916 png_bytep sp = row + (size_t)row_width * 2 - 1;
2917 png_bytep dp = sp + (size_t)row_width * 4;
2918 for (i = 0; i < row_width; i++)
2919 {
2920 *(dp--) = *sp;
2921 *(dp--) = *(sp - 1);
2922 *(dp--) = *sp;
2923 *(dp--) = *(sp - 1);
2924 *(dp--) = *(sp--);
2925 *(dp--) = *(sp--);
2926 }
2927 }
2928 }
2929
2930 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2931 {
2932 if (row_info->bit_depth == 8)
2933 {
2934 /* This changes GA to RGBA */
2935 png_bytep sp = row + (size_t)row_width * 2 - 1;
2936 png_bytep dp = sp + (size_t)row_width * 2;
2937 for (i = 0; i < row_width; i++)
2938 {
2939 *(dp--) = *(sp--);
2940 *(dp--) = *sp;
2941 *(dp--) = *sp;
2942 *(dp--) = *(sp--);
2943 }
2944 }
2945
2946 else
2947 {
2948 /* This changes GGAA to RRGGBBAA */
2949 png_bytep sp = row + (size_t)row_width * 4 - 1;
2950 png_bytep dp = sp + (size_t)row_width * 4;
2951 for (i = 0; i < row_width; i++)
2952 {
2953 *(dp--) = *(sp--);
2954 *(dp--) = *(sp--);
2955 *(dp--) = *sp;
2956 *(dp--) = *(sp - 1);
2957 *(dp--) = *sp;
2958 *(dp--) = *(sp - 1);
2959 *(dp--) = *(sp--);
2960 *(dp--) = *(sp--);
2961 }
2962 }
2963 }
2964 row_info->channels = (png_byte)(row_info->channels + 2);
2965 row_info->color_type |= PNG_COLOR_MASK_COLOR;
2966 row_info->pixel_depth = (png_byte)(row_info->channels *
2967 row_info->bit_depth);
2968 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
2969 }
2970 }
2971 #endif
2972
2973 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2974 /* Reduce RGB files to grayscale, with or without alpha
2975 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
2976 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
2977 * versions dated 1998 through November 2002 have been archived at
2978 * https://web.archive.org/web/20000816232553/www.inforamp.net/
2979 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
2980 * Charles Poynton poynton at poynton.com
2981 *
2982 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
2983 *
2984 * which can be expressed with integers as
2985 *
2986 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
2987 *
2988 * Poynton's current link (as of January 2003 through July 2011):
2989 * <http://www.poynton.com/notes/colour_and_gamma/>
2990 * has changed the numbers slightly:
2991 *
2992 * Y = 0.2126*R + 0.7152*G + 0.0722*B
2993 *
2994 * which can be expressed with integers as
2995 *
2996 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
2997 *
2998 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
2999 * end point chromaticities and the D65 white point. Depending on the
3000 * precision used for the D65 white point this produces a variety of different
3001 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
3002 * used (0.3127,0.3290) the Y calculation would be:
3003 *
3004 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
3005 *
3006 * While this is correct the rounding results in an overflow for white, because
3007 * the sum of the rounded coefficients is 32769, not 32768. Consequently
3008 * libpng uses, instead, the closest non-overflowing approximation:
3009 *
3010 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
3011 *
3012 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
3013 * (including an sRGB chunk) then the chromaticities are used to calculate the
3014 * coefficients. See the chunk handling in pngrutil.c for more information.
3015 *
3016 * In all cases the calculation is to be done in a linear colorspace. If no
3017 * gamma information is available to correct the encoding of the original RGB
3018 * values this results in an implicit assumption that the original PNG RGB
3019 * values were linear.
3020 *
3021 * Other integer coefficients can be used via png_set_rgb_to_gray(). Because
3022 * the API takes just red and green coefficients the blue coefficient is
3023 * calculated to make the sum 32768. This will result in different rounding
3024 * to that used above.
3025 */
3026 static int
3027 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
3028 {
3029 int rgb_error = 0;
3030
3031 png_debug(1, "in png_do_rgb_to_gray");
3032
3033 if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
3034 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
3035 {
3036 png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
3037 png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
3038 png_uint_32 bc = 32768 - rc - gc;
3039 png_uint_32 row_width = row_info->width;
3040 int have_alpha = (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
3041
3042 if (row_info->bit_depth == 8)
3043 {
3044 #ifdef PNG_READ_GAMMA_SUPPORTED
3045 /* Notice that gamma to/from 1 are not necessarily inverses (if
3046 * there is an overall gamma correction). Prior to 1.5.5 this code
3047 * checked the linearized values for equality; this doesn't match
3048 * the documentation, the original values must be checked.
3049 */
3050 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
3051 {
3052 png_bytep sp = row;
3053 png_bytep dp = row;
3054 png_uint_32 i;
3055
3056 for (i = 0; i < row_width; i++)
3057 {
3058 png_byte red = *(sp++);
3059 png_byte green = *(sp++);
3060 png_byte blue = *(sp++);
3061
3062 if (red != green || red != blue)
3063 {
3064 red = png_ptr->gamma_to_1[red];
3065 green = png_ptr->gamma_to_1[green];
3066 blue = png_ptr->gamma_to_1[blue];
3067
3068 rgb_error |= 1;
3069 *(dp++) = png_ptr->gamma_from_1[
3070 (rc*red + gc*green + bc*blue + 16384)>>15];
3071 }
3072
3073 else
3074 {
3075 /* If there is no overall correction the table will not be
3076 * set.
3077 */
3078 if (png_ptr->gamma_table != NULL)
3079 red = png_ptr->gamma_table[red];
3080
3081 *(dp++) = red;
3082 }
3083
3084 if (have_alpha != 0)
3085 *(dp++) = *(sp++);
3086 }
3087 }
3088 else
3089 #endif
3090 {
3091 png_bytep sp = row;
3092 png_bytep dp = row;
3093 png_uint_32 i;
3094
3095 for (i = 0; i < row_width; i++)
3096 {
3097 png_byte red = *(sp++);
3098 png_byte green = *(sp++);
3099 png_byte blue = *(sp++);
3100
3101 if (red != green || red != blue)
3102 {
3103 rgb_error |= 1;
3104 /* NOTE: this is the historical approach which simply
3105 * truncates the results.
3106 */
3107 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
3108 }
3109
3110 else
3111 *(dp++) = red;
3112
3113 if (have_alpha != 0)
3114 *(dp++) = *(sp++);
3115 }
3116 }
3117 }
3118
3119 else /* RGB bit_depth == 16 */
3120 {
3121 #ifdef PNG_READ_GAMMA_SUPPORTED
3122 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
3123 {
3124 png_bytep sp = row;
3125 png_bytep dp = row;
3126 png_uint_32 i;
3127
3128 for (i = 0; i < row_width; i++)
3129 {
3130 png_uint_16 red, green, blue, w;
3131 png_byte hi,lo;
3132
3133 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3134 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3135 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3136
3137 if (red == green && red == blue)
3138 {
3139 if (png_ptr->gamma_16_table != NULL)
3140 w = png_ptr->gamma_16_table[(red & 0xff)
3141 >> png_ptr->gamma_shift][red >> 8];
3142
3143 else
3144 w = red;
3145 }
3146
3147 else
3148 {
3149 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red & 0xff)
3150 >> png_ptr->gamma_shift][red>>8];
3151 png_uint_16 green_1 =
3152 png_ptr->gamma_16_to_1[(green & 0xff) >>
3153 png_ptr->gamma_shift][green>>8];
3154 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue & 0xff)
3155 >> png_ptr->gamma_shift][blue>>8];
3156 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
3157 + bc*blue_1 + 16384)>>15);
3158 w = png_ptr->gamma_16_from_1[(gray16 & 0xff) >>
3159 png_ptr->gamma_shift][gray16 >> 8];
3160 rgb_error |= 1;
3161 }
3162
3163 *(dp++) = (png_byte)((w>>8) & 0xff);
3164 *(dp++) = (png_byte)(w & 0xff);
3165
3166 if (have_alpha != 0)
3167 {
3168 *(dp++) = *(sp++);
3169 *(dp++) = *(sp++);
3170 }
3171 }
3172 }
3173 else
3174 #endif
3175 {
3176 png_bytep sp = row;
3177 png_bytep dp = row;
3178 png_uint_32 i;
3179
3180 for (i = 0; i < row_width; i++)
3181 {
3182 png_uint_16 red, green, blue, gray16;
3183 png_byte hi,lo;
3184
3185 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3186 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3187 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3188
3189 if (red != green || red != blue)
3190 rgb_error |= 1;
3191
3192 /* From 1.5.5 in the 16-bit case do the accurate conversion even
3193 * in the 'fast' case - this is because this is where the code
3194 * ends up when handling linear 16-bit data.
3195 */
3196 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
3197 15);
3198 *(dp++) = (png_byte)((gray16 >> 8) & 0xff);
3199 *(dp++) = (png_byte)(gray16 & 0xff);
3200
3201 if (have_alpha != 0)
3202 {
3203 *(dp++) = *(sp++);
3204 *(dp++) = *(sp++);
3205 }
3206 }
3207 }
3208 }
3209
3210 row_info->channels = (png_byte)(row_info->channels - 2);
3211 row_info->color_type = (png_byte)(row_info->color_type &
3212 ~PNG_COLOR_MASK_COLOR);
3213 row_info->pixel_depth = (png_byte)(row_info->channels *
3214 row_info->bit_depth);
3215 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3216 }
3217 return rgb_error;
3218 }
3219 #endif
3220
3221 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
3222 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
3223 /* Replace any alpha or transparency with the supplied background color.
3224 * "background" is already in the screen gamma, while "background_1" is
3225 * at a gamma of 1.0. Paletted files have already been taken care of.
3226 */
3227 static void
3228 png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3229 {
3230 #ifdef PNG_READ_GAMMA_SUPPORTED
3231 png_const_bytep gamma_table = png_ptr->gamma_table;
3232 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
3233 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
3234 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
3235 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
3236 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
3237 int gamma_shift = png_ptr->gamma_shift;
3238 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
3239 #endif
3240
3241 png_bytep sp;
3242 png_uint_32 i;
3243 png_uint_32 row_width = row_info->width;
3244 int shift;
3245
3246 png_debug(1, "in png_do_compose");
3247
3248 switch (row_info->color_type)
3249 {
3250 case PNG_COLOR_TYPE_GRAY:
3251 {
3252 switch (row_info->bit_depth)
3253 {
3254 case 1:
3255 {
3256 sp = row;
3257 shift = 7;
3258 for (i = 0; i < row_width; i++)
3259 {
3260 if ((png_uint_16)((*sp >> shift) & 0x01)
3261 == png_ptr->trans_color.gray)
3262 {
3263 unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
3264 tmp |=
3265 (unsigned int)(png_ptr->background.gray << shift);
3266 *sp = (png_byte)(tmp & 0xff);
3267 }
3268
3269 if (shift == 0)
3270 {
3271 shift = 7;
3272 sp++;
3273 }
3274
3275 else
3276 shift--;
3277 }
3278 break;
3279 }
3280
3281 case 2:
3282 {
3283 #ifdef PNG_READ_GAMMA_SUPPORTED
3284 if (gamma_table != NULL)
3285 {
3286 sp = row;
3287 shift = 6;
3288 for (i = 0; i < row_width; i++)
3289 {
3290 if ((png_uint_16)((*sp >> shift) & 0x03)
3291 == png_ptr->trans_color.gray)
3292 {
3293 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3294 tmp |=
3295 (unsigned int)png_ptr->background.gray << shift;
3296 *sp = (png_byte)(tmp & 0xff);
3297 }
3298
3299 else
3300 {
3301 unsigned int p = (*sp >> shift) & 0x03;
3302 unsigned int g = (gamma_table [p | (p << 2) |
3303 (p << 4) | (p << 6)] >> 6) & 0x03;
3304 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3305 tmp |= (unsigned int)(g << shift);
3306 *sp = (png_byte)(tmp & 0xff);
3307 }
3308
3309 if (shift == 0)
3310 {
3311 shift = 6;
3312 sp++;
3313 }
3314
3315 else
3316 shift -= 2;
3317 }
3318 }
3319
3320 else
3321 #endif
3322 {
3323 sp = row;
3324 shift = 6;
3325 for (i = 0; i < row_width; i++)
3326 {
3327 if ((png_uint_16)((*sp >> shift) & 0x03)
3328 == png_ptr->trans_color.gray)
3329 {
3330 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3331 tmp |=
3332 (unsigned int)png_ptr->background.gray << shift;
3333 *sp = (png_byte)(tmp & 0xff);
3334 }
3335
3336 if (shift == 0)
3337 {
3338 shift = 6;
3339 sp++;
3340 }
3341
3342 else
3343 shift -= 2;
3344 }
3345 }
3346 break;
3347 }
3348
3349 case 4:
3350 {
3351 #ifdef PNG_READ_GAMMA_SUPPORTED
3352 if (gamma_table != NULL)
3353 {
3354 sp = row;
3355 shift = 4;
3356 for (i = 0; i < row_width; i++)
3357 {
3358 if ((png_uint_16)((*sp >> shift) & 0x0f)
3359 == png_ptr->trans_color.gray)
3360 {
3361 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3362 tmp |=
3363 (unsigned int)(png_ptr->background.gray << shift);
3364 *sp = (png_byte)(tmp & 0xff);
3365 }
3366
3367 else
3368 {
3369 unsigned int p = (*sp >> shift) & 0x0f;
3370 unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
3371 0x0f;
3372 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3373 tmp |= (unsigned int)(g << shift);
3374 *sp = (png_byte)(tmp & 0xff);
3375 }
3376
3377 if (shift == 0)
3378 {
3379 shift = 4;
3380 sp++;
3381 }
3382
3383 else
3384 shift -= 4;
3385 }
3386 }
3387
3388 else
3389 #endif
3390 {
3391 sp = row;
3392 shift = 4;
3393 for (i = 0; i < row_width; i++)
3394 {
3395 if ((png_uint_16)((*sp >> shift) & 0x0f)
3396 == png_ptr->trans_color.gray)
3397 {
3398 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3399 tmp |=
3400 (unsigned int)(png_ptr->background.gray << shift);
3401 *sp = (png_byte)(tmp & 0xff);
3402 }
3403
3404 if (shift == 0)
3405 {
3406 shift = 4;
3407 sp++;
3408 }
3409
3410 else
3411 shift -= 4;
3412 }
3413 }
3414 break;
3415 }
3416
3417 case 8:
3418 {
3419 #ifdef PNG_READ_GAMMA_SUPPORTED
3420 if (gamma_table != NULL)
3421 {
3422 sp = row;
3423 for (i = 0; i < row_width; i++, sp++)
3424 {
3425 if (*sp == png_ptr->trans_color.gray)
3426 *sp = (png_byte)png_ptr->background.gray;
3427
3428 else
3429 *sp = gamma_table[*sp];
3430 }
3431 }
3432 else
3433 #endif
3434 {
3435 sp = row;
3436 for (i = 0; i < row_width; i++, sp++)
3437 {
3438 if (*sp == png_ptr->trans_color.gray)
3439 *sp = (png_byte)png_ptr->background.gray;
3440 }
3441 }
3442 break;
3443 }
3444
3445 case 16:
3446 {
3447 #ifdef PNG_READ_GAMMA_SUPPORTED
3448 if (gamma_16 != NULL)
3449 {
3450 sp = row;
3451 for (i = 0; i < row_width; i++, sp += 2)
3452 {
3453 png_uint_16 v;
3454
3455 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3456
3457 if (v == png_ptr->trans_color.gray)
3458 {
3459 /* Background is already in screen gamma */
3460 *sp = (png_byte)((png_ptr->background.gray >> 8)
3461 & 0xff);
3462 *(sp + 1) = (png_byte)(png_ptr->background.gray
3463 & 0xff);
3464 }
3465
3466 else
3467 {
3468 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3469 *sp = (png_byte)((v >> 8) & 0xff);
3470 *(sp + 1) = (png_byte)(v & 0xff);
3471 }
3472 }
3473 }
3474 else
3475 #endif
3476 {
3477 sp = row;
3478 for (i = 0; i < row_width; i++, sp += 2)
3479 {
3480 png_uint_16 v;
3481
3482 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3483
3484 if (v == png_ptr->trans_color.gray)
3485 {
3486 *sp = (png_byte)((png_ptr->background.gray >> 8)
3487 & 0xff);
3488 *(sp + 1) = (png_byte)(png_ptr->background.gray
3489 & 0xff);
3490 }
3491 }
3492 }
3493 break;
3494 }
3495
3496 default:
3497 break;
3498 }
3499 break;
3500 }
3501
3502 case PNG_COLOR_TYPE_RGB:
3503 {
3504 if (row_info->bit_depth == 8)
3505 {
3506 #ifdef PNG_READ_GAMMA_SUPPORTED
3507 if (gamma_table != NULL)
3508 {
3509 sp = row;
3510 for (i = 0; i < row_width; i++, sp += 3)
3511 {
3512 if (*sp == png_ptr->trans_color.red &&
3513 *(sp + 1) == png_ptr->trans_color.green &&
3514 *(sp + 2) == png_ptr->trans_color.blue)
3515 {
3516 *sp = (png_byte)png_ptr->background.red;
3517 *(sp + 1) = (png_byte)png_ptr->background.green;
3518 *(sp + 2) = (png_byte)png_ptr->background.blue;
3519 }
3520
3521 else
3522 {
3523 *sp = gamma_table[*sp];
3524 *(sp + 1) = gamma_table[*(sp + 1)];
3525 *(sp + 2) = gamma_table[*(sp + 2)];
3526 }
3527 }
3528 }
3529 else
3530 #endif
3531 {
3532 sp = row;
3533 for (i = 0; i < row_width; i++, sp += 3)
3534 {
3535 if (*sp == png_ptr->trans_color.red &&
3536 *(sp + 1) == png_ptr->trans_color.green &&
3537 *(sp + 2) == png_ptr->trans_color.blue)
3538 {
3539 *sp = (png_byte)png_ptr->background.red;
3540 *(sp + 1) = (png_byte)png_ptr->background.green;
3541 *(sp + 2) = (png_byte)png_ptr->background.blue;
3542 }
3543 }
3544 }
3545 }
3546 else /* if (row_info->bit_depth == 16) */
3547 {
3548 #ifdef PNG_READ_GAMMA_SUPPORTED
3549 if (gamma_16 != NULL)
3550 {
3551 sp = row;
3552 for (i = 0; i < row_width; i++, sp += 6)
3553 {
3554 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3555
3556 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3557 + *(sp + 3));
3558
3559 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3560 + *(sp + 5));
3561
3562 if (r == png_ptr->trans_color.red &&
3563 g == png_ptr->trans_color.green &&
3564 b == png_ptr->trans_color.blue)
3565 {
3566 /* Background is already in screen gamma */
3567 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3568 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3569 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3570 & 0xff);
3571 *(sp + 3) = (png_byte)(png_ptr->background.green
3572 & 0xff);
3573 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3574 & 0xff);
3575 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3576 }
3577
3578 else
3579 {
3580 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3581 *sp = (png_byte)((v >> 8) & 0xff);
3582 *(sp + 1) = (png_byte)(v & 0xff);
3583
3584 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3585 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3586 *(sp + 3) = (png_byte)(v & 0xff);
3587
3588 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3589 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3590 *(sp + 5) = (png_byte)(v & 0xff);
3591 }
3592 }
3593 }
3594
3595 else
3596 #endif
3597 {
3598 sp = row;
3599 for (i = 0; i < row_width; i++, sp += 6)
3600 {
3601 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3602
3603 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3604 + *(sp + 3));
3605
3606 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3607 + *(sp + 5));
3608
3609 if (r == png_ptr->trans_color.red &&
3610 g == png_ptr->trans_color.green &&
3611 b == png_ptr->trans_color.blue)
3612 {
3613 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3614 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3615 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3616 & 0xff);
3617 *(sp + 3) = (png_byte)(png_ptr->background.green
3618 & 0xff);
3619 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3620 & 0xff);
3621 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3622 }
3623 }
3624 }
3625 }
3626 break;
3627 }
3628
3629 case PNG_COLOR_TYPE_GRAY_ALPHA:
3630 {
3631 if (row_info->bit_depth == 8)
3632 {
3633 #ifdef PNG_READ_GAMMA_SUPPORTED
3634 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3635 gamma_table != NULL)
3636 {
3637 sp = row;
3638 for (i = 0; i < row_width; i++, sp += 2)
3639 {
3640 png_uint_16 a = *(sp + 1);
3641
3642 if (a == 0xff)
3643 *sp = gamma_table[*sp];
3644
3645 else if (a == 0)
3646 {
3647 /* Background is already in screen gamma */
3648 *sp = (png_byte)png_ptr->background.gray;
3649 }
3650
3651 else
3652 {
3653 png_byte v, w;
3654
3655 v = gamma_to_1[*sp];
3656 png_composite(w, v, a, png_ptr->background_1.gray);
3657 if (optimize == 0)
3658 w = gamma_from_1[w];
3659 *sp = w;
3660 }
3661 }
3662 }
3663 else
3664 #endif
3665 {
3666 sp = row;
3667 for (i = 0; i < row_width; i++, sp += 2)
3668 {
3669 png_byte a = *(sp + 1);
3670
3671 if (a == 0)
3672 *sp = (png_byte)png_ptr->background.gray;
3673
3674 else if (a < 0xff)
3675 png_composite(*sp, *sp, a, png_ptr->background.gray);
3676 }
3677 }
3678 }
3679 else /* if (png_ptr->bit_depth == 16) */
3680 {
3681 #ifdef PNG_READ_GAMMA_SUPPORTED
3682 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3683 gamma_16_to_1 != NULL)
3684 {
3685 sp = row;
3686 for (i = 0; i < row_width; i++, sp += 4)
3687 {
3688 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3689 + *(sp + 3));
3690
3691 if (a == (png_uint_16)0xffff)
3692 {
3693 png_uint_16 v;
3694
3695 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3696 *sp = (png_byte)((v >> 8) & 0xff);
3697 *(sp + 1) = (png_byte)(v & 0xff);
3698 }
3699
3700 else if (a == 0)
3701 {
3702 /* Background is already in screen gamma */
3703 *sp = (png_byte)((png_ptr->background.gray >> 8)
3704 & 0xff);
3705 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3706 }
3707
3708 else
3709 {
3710 png_uint_16 g, v, w;
3711
3712 g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3713 png_composite_16(v, g, a, png_ptr->background_1.gray);
3714 if (optimize != 0)
3715 w = v;
3716 else
3717 w = gamma_16_from_1[(v & 0xff) >>
3718 gamma_shift][v >> 8];
3719 *sp = (png_byte)((w >> 8) & 0xff);
3720 *(sp + 1) = (png_byte)(w & 0xff);
3721 }
3722 }
3723 }
3724 else
3725 #endif
3726 {
3727 sp = row;
3728 for (i = 0; i < row_width; i++, sp += 4)
3729 {
3730 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3731 + *(sp + 3));
3732
3733 if (a == 0)
3734 {
3735 *sp = (png_byte)((png_ptr->background.gray >> 8)
3736 & 0xff);
3737 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3738 }
3739
3740 else if (a < 0xffff)
3741 {
3742 png_uint_16 g, v;
3743
3744 g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3745 png_composite_16(v, g, a, png_ptr->background.gray);
3746 *sp = (png_byte)((v >> 8) & 0xff);
3747 *(sp + 1) = (png_byte)(v & 0xff);
3748 }
3749 }
3750 }
3751 }
3752 break;
3753 }
3754
3755 case PNG_COLOR_TYPE_RGB_ALPHA:
3756 {
3757 if (row_info->bit_depth == 8)
3758 {
3759 #ifdef PNG_READ_GAMMA_SUPPORTED
3760 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3761 gamma_table != NULL)
3762 {
3763 sp = row;
3764 for (i = 0; i < row_width; i++, sp += 4)
3765 {
3766 png_byte a = *(sp + 3);
3767
3768 if (a == 0xff)
3769 {
3770 *sp = gamma_table[*sp];
3771 *(sp + 1) = gamma_table[*(sp + 1)];
3772 *(sp + 2) = gamma_table[*(sp + 2)];
3773 }
3774
3775 else if (a == 0)
3776 {
3777 /* Background is already in screen gamma */
3778 *sp = (png_byte)png_ptr->background.red;
3779 *(sp + 1) = (png_byte)png_ptr->background.green;
3780 *(sp + 2) = (png_byte)png_ptr->background.blue;
3781 }
3782
3783 else
3784 {
3785 png_byte v, w;
3786
3787 v = gamma_to_1[*sp];
3788 png_composite(w, v, a, png_ptr->background_1.red);
3789 if (optimize == 0) w = gamma_from_1[w];
3790 *sp = w;
3791
3792 v = gamma_to_1[*(sp + 1)];
3793 png_composite(w, v, a, png_ptr->background_1.green);
3794 if (optimize == 0) w = gamma_from_1[w];
3795 *(sp + 1) = w;
3796
3797 v = gamma_to_1[*(sp + 2)];
3798 png_composite(w, v, a, png_ptr->background_1.blue);
3799 if (optimize == 0) w = gamma_from_1[w];
3800 *(sp + 2) = w;
3801 }
3802 }
3803 }
3804 else
3805 #endif
3806 {
3807 sp = row;
3808 for (i = 0; i < row_width; i++, sp += 4)
3809 {
3810 png_byte a = *(sp + 3);
3811
3812 if (a == 0)
3813 {
3814 *sp = (png_byte)png_ptr->background.red;
3815 *(sp + 1) = (png_byte)png_ptr->background.green;
3816 *(sp + 2) = (png_byte)png_ptr->background.blue;
3817 }
3818
3819 else if (a < 0xff)
3820 {
3821 png_composite(*sp, *sp, a, png_ptr->background.red);
3822
3823 png_composite(*(sp + 1), *(sp + 1), a,
3824 png_ptr->background.green);
3825
3826 png_composite(*(sp + 2), *(sp + 2), a,
3827 png_ptr->background.blue);
3828 }
3829 }
3830 }
3831 }
3832 else /* if (row_info->bit_depth == 16) */
3833 {
3834 #ifdef PNG_READ_GAMMA_SUPPORTED
3835 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3836 gamma_16_to_1 != NULL)
3837 {
3838 sp = row;
3839 for (i = 0; i < row_width; i++, sp += 8)
3840 {
3841 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3842 << 8) + (png_uint_16)(*(sp + 7)));
3843
3844 if (a == (png_uint_16)0xffff)
3845 {
3846 png_uint_16 v;
3847
3848 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3849 *sp = (png_byte)((v >> 8) & 0xff);
3850 *(sp + 1) = (png_byte)(v & 0xff);
3851
3852 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3853 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3854 *(sp + 3) = (png_byte)(v & 0xff);
3855
3856 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3857 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3858 *(sp + 5) = (png_byte)(v & 0xff);
3859 }
3860
3861 else if (a == 0)
3862 {
3863 /* Background is already in screen gamma */
3864 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3865 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3866 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3867 & 0xff);
3868 *(sp + 3) = (png_byte)(png_ptr->background.green
3869 & 0xff);
3870 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3871 & 0xff);
3872 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3873 }
3874
3875 else
3876 {
3877 png_uint_16 v, w;
3878
3879 v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3880 png_composite_16(w, v, a, png_ptr->background_1.red);
3881 if (optimize == 0)
3882 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3883 8];
3884 *sp = (png_byte)((w >> 8) & 0xff);
3885 *(sp + 1) = (png_byte)(w & 0xff);
3886
3887 v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
3888 png_composite_16(w, v, a, png_ptr->background_1.green);
3889 if (optimize == 0)
3890 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3891 8];
3892
3893 *(sp + 2) = (png_byte)((w >> 8) & 0xff);
3894 *(sp + 3) = (png_byte)(w & 0xff);
3895
3896 v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
3897 png_composite_16(w, v, a, png_ptr->background_1.blue);
3898 if (optimize == 0)
3899 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3900 8];
3901
3902 *(sp + 4) = (png_byte)((w >> 8) & 0xff);
3903 *(sp + 5) = (png_byte)(w & 0xff);
3904 }
3905 }
3906 }
3907
3908 else
3909 #endif
3910 {
3911 sp = row;
3912 for (i = 0; i < row_width; i++, sp += 8)
3913 {
3914 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3915 << 8) + (png_uint_16)(*(sp + 7)));
3916
3917 if (a == 0)
3918 {
3919 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3920 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3921 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3922 & 0xff);
3923 *(sp + 3) = (png_byte)(png_ptr->background.green
3924 & 0xff);
3925 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3926 & 0xff);
3927 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3928 }
3929
3930 else if (a < 0xffff)
3931 {
3932 png_uint_16 v;
3933
3934 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3935 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3936 + *(sp + 3));
3937 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3938 + *(sp + 5));
3939
3940 png_composite_16(v, r, a, png_ptr->background.red);
3941 *sp = (png_byte)((v >> 8) & 0xff);
3942 *(sp + 1) = (png_byte)(v & 0xff);
3943
3944 png_composite_16(v, g, a, png_ptr->background.green);
3945 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3946 *(sp + 3) = (png_byte)(v & 0xff);
3947
3948 png_composite_16(v, b, a, png_ptr->background.blue);
3949 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3950 *(sp + 5) = (png_byte)(v & 0xff);
3951 }
3952 }
3953 }
3954 }
3955 break;
3956 }
3957
3958 default:
3959 break;
3960 }
3961 }
3962 #endif /* READ_BACKGROUND || READ_ALPHA_MODE */
3963
3964 #ifdef PNG_READ_GAMMA_SUPPORTED
3965 /* Gamma correct the image, avoiding the alpha channel. Make sure
3966 * you do this after you deal with the transparency issue on grayscale
3967 * or RGB images. If your bit depth is 8, use gamma_table, if it
3968 * is 16, use gamma_16_table and gamma_shift. Build these with
3969 * build_gamma_table().
3970 */
3971 static void
3972 png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3973 {
3974 png_const_bytep gamma_table = png_ptr->gamma_table;
3975 png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
3976 int gamma_shift = png_ptr->gamma_shift;
3977
3978 png_bytep sp;
3979 png_uint_32 i;
3980 png_uint_32 row_width=row_info->width;
3981
3982 png_debug(1, "in png_do_gamma");
3983
3984 if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
3985 (row_info->bit_depth == 16 && gamma_16_table != NULL)))
3986 {
3987 switch (row_info->color_type)
3988 {
3989 case PNG_COLOR_TYPE_RGB:
3990 {
3991 if (row_info->bit_depth == 8)
3992 {
3993 sp = row;
3994 for (i = 0; i < row_width; i++)
3995 {
3996 *sp = gamma_table[*sp];
3997 sp++;
3998 *sp = gamma_table[*sp];
3999 sp++;
4000 *sp = gamma_table[*sp];
4001 sp++;
4002 }
4003 }
4004
4005 else /* if (row_info->bit_depth == 16) */
4006 {
4007 sp = row;
4008 for (i = 0; i < row_width; i++)
4009 {
4010 png_uint_16 v;
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 += 2;
4021
4022 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4023 *sp = (png_byte)((v >> 8) & 0xff);
4024 *(sp + 1) = (png_byte)(v & 0xff);
4025 sp += 2;
4026 }
4027 }
4028 break;
4029 }
4030
4031 case PNG_COLOR_TYPE_RGB_ALPHA:
4032 {
4033 if (row_info->bit_depth == 8)
4034 {
4035 sp = row;
4036 for (i = 0; i < row_width; i++)
4037 {
4038 *sp = gamma_table[*sp];
4039 sp++;
4040
4041 *sp = gamma_table[*sp];
4042 sp++;
4043
4044 *sp = gamma_table[*sp];
4045 sp++;
4046
4047 sp++;
4048 }
4049 }
4050
4051 else /* if (row_info->bit_depth == 16) */
4052 {
4053 sp = row;
4054 for (i = 0; i < row_width; i++)
4055 {
4056 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4057 *sp = (png_byte)((v >> 8) & 0xff);
4058 *(sp + 1) = (png_byte)(v & 0xff);
4059 sp += 2;
4060
4061 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4062 *sp = (png_byte)((v >> 8) & 0xff);
4063 *(sp + 1) = (png_byte)(v & 0xff);
4064 sp += 2;
4065
4066 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4067 *sp = (png_byte)((v >> 8) & 0xff);
4068 *(sp + 1) = (png_byte)(v & 0xff);
4069 sp += 4;
4070 }
4071 }
4072 break;
4073 }
4074
4075 case PNG_COLOR_TYPE_GRAY_ALPHA:
4076 {
4077 if (row_info->bit_depth == 8)
4078 {
4079 sp = row;
4080 for (i = 0; i < row_width; i++)
4081 {
4082 *sp = gamma_table[*sp];
4083 sp += 2;
4084 }
4085 }
4086
4087 else /* if (row_info->bit_depth == 16) */
4088 {
4089 sp = row;
4090 for (i = 0; i < row_width; i++)
4091 {
4092 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4093 *sp = (png_byte)((v >> 8) & 0xff);
4094 *(sp + 1) = (png_byte)(v & 0xff);
4095 sp += 4;
4096 }
4097 }
4098 break;
4099 }
4100
4101 case PNG_COLOR_TYPE_GRAY:
4102 {
4103 if (row_info->bit_depth == 2)
4104 {
4105 sp = row;
4106 for (i = 0; i < row_width; i += 4)
4107 {
4108 int a = *sp & 0xc0;
4109 int b = *sp & 0x30;
4110 int c = *sp & 0x0c;
4111 int d = *sp & 0x03;
4112
4113 *sp = (png_byte)(
4114 ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)|
4115 ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
4116 ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
4117 ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
4118 sp++;
4119 }
4120 }
4121
4122 if (row_info->bit_depth == 4)
4123 {
4124 sp = row;
4125 for (i = 0; i < row_width; i += 2)
4126 {
4127 int msb = *sp & 0xf0;
4128 int lsb = *sp & 0x0f;
4129
4130 *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
4131 | (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
4132 sp++;
4133 }
4134 }
4135
4136 else if (row_info->bit_depth == 8)
4137 {
4138 sp = row;
4139 for (i = 0; i < row_width; i++)
4140 {
4141 *sp = gamma_table[*sp];
4142 sp++;
4143 }
4144 }
4145
4146 else if (row_info->bit_depth == 16)
4147 {
4148 sp = row;
4149 for (i = 0; i < row_width; i++)
4150 {
4151 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4152 *sp = (png_byte)((v >> 8) & 0xff);
4153 *(sp + 1) = (png_byte)(v & 0xff);
4154 sp += 2;
4155 }
4156 }
4157 break;
4158 }
4159
4160 default:
4161 break;
4162 }
4163 }
4164 }
4165 #endif
4166
4167 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4168 /* Encode the alpha channel to the output gamma (the input channel is always
4169 * linear.) Called only with color types that have an alpha channel. Needs the
4170 * from_1 tables.
4171 */
4172 static void
4173 png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
4174 {
4175 png_uint_32 row_width = row_info->width;
4176
4177 png_debug(1, "in png_do_encode_alpha");
4178
4179 if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4180 {
4181 if (row_info->bit_depth == 8)
4182 {
4183 png_bytep table = png_ptr->gamma_from_1;
4184
4185 if (table != NULL)
4186 {
4187 int step = (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
4188
4189 /* The alpha channel is the last component: */
4190 row += step - 1;
4191
4192 for (; row_width > 0; --row_width, row += step)
4193 *row = table[*row];
4194
4195 return;
4196 }
4197 }
4198
4199 else if (row_info->bit_depth == 16)
4200 {
4201 png_uint_16pp table = png_ptr->gamma_16_from_1;
4202 int gamma_shift = png_ptr->gamma_shift;
4203
4204 if (table != NULL)
4205 {
4206 int step = (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
4207
4208 /* The alpha channel is the last component: */
4209 row += step - 2;
4210
4211 for (; row_width > 0; --row_width, row += step)
4212 {
4213 png_uint_16 v;
4214
4215 v = table[*(row + 1) >> gamma_shift][*row];
4216 *row = (png_byte)((v >> 8) & 0xff);
4217 *(row + 1) = (png_byte)(v & 0xff);
4218 }
4219
4220 return;
4221 }
4222 }
4223 }
4224
4225 /* Only get to here if called with a weird row_info; no harm has been done,
4226 * so just issue a warning.
4227 */
4228 png_warning(png_ptr, "png_do_encode_alpha: unexpected call");
4229 }
4230 #endif
4231
4232 #ifdef PNG_READ_EXPAND_SUPPORTED
4233 /* Expands a palette row to an RGB or RGBA row depending
4234 * upon whether you supply trans and num_trans.
4235 */
4236 static void
4237 png_do_expand_palette(png_structrp png_ptr, png_row_infop row_info,
4238 png_bytep row, png_const_colorp palette, png_const_bytep trans_alpha,
4239 int num_trans)
4240 {
4241 int shift, value;
4242 png_bytep sp, dp;
4243 png_uint_32 i;
4244 png_uint_32 row_width=row_info->width;
4245
4246 png_debug(1, "in png_do_expand_palette");
4247
4248 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4249 {
4250 if (row_info->bit_depth < 8)
4251 {
4252 switch (row_info->bit_depth)
4253 {
4254 case 1:
4255 {
4256 sp = row + (size_t)((row_width - 1) >> 3);
4257 dp = row + (size_t)row_width - 1;
4258 shift = 7 - (int)((row_width + 7) & 0x07);
4259 for (i = 0; i < row_width; i++)
4260 {
4261 if ((*sp >> shift) & 0x01)
4262 *dp = 1;
4263
4264 else
4265 *dp = 0;
4266
4267 if (shift == 7)
4268 {
4269 shift = 0;
4270 sp--;
4271 }
4272
4273 else
4274 shift++;
4275
4276 dp--;
4277 }
4278 break;
4279 }
4280
4281 case 2:
4282 {
4283 sp = row + (size_t)((row_width - 1) >> 2);
4284 dp = row + (size_t)row_width - 1;
4285 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4286 for (i = 0; i < row_width; i++)
4287 {
4288 value = (*sp >> shift) & 0x03;
4289 *dp = (png_byte)value;
4290 if (shift == 6)
4291 {
4292 shift = 0;
4293 sp--;
4294 }
4295
4296 else
4297 shift += 2;
4298
4299 dp--;
4300 }
4301 break;
4302 }
4303
4304 case 4:
4305 {
4306 sp = row + (size_t)((row_width - 1) >> 1);
4307 dp = row + (size_t)row_width - 1;
4308 shift = (int)((row_width & 0x01) << 2);
4309 for (i = 0; i < row_width; i++)
4310 {
4311 value = (*sp >> shift) & 0x0f;
4312 *dp = (png_byte)value;
4313 if (shift == 4)
4314 {
4315 shift = 0;
4316 sp--;
4317 }
4318
4319 else
4320 shift += 4;
4321
4322 dp--;
4323 }
4324 break;
4325 }
4326
4327 default:
4328 break;
4329 }
4330 row_info->bit_depth = 8;
4331 row_info->pixel_depth = 8;
4332 row_info->rowbytes = row_width;
4333 }
4334
4335 if (row_info->bit_depth == 8)
4336 {
4337 {
4338 if (num_trans > 0)
4339 {
4340 sp = row + (size_t)row_width - 1;
4341 dp = row + ((size_t)row_width << 2) - 1;
4342
4343 i = 0;
4344 #ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
4345 if (png_ptr->riffled_palette != NULL)
4346 {
4347 /* The RGBA optimization works with png_ptr->bit_depth == 8
4348 * but sometimes row_info->bit_depth has been changed to 8.
4349 * In these cases, the palette hasn't been riffled.
4350 */
4351 i = png_do_expand_palette_rgba8_neon(png_ptr, row_info, row,
4352 &sp, &dp);
4353 }
4354 #else
4355 PNG_UNUSED(png_ptr)
4356 #endif
4357
4358 for (; i < row_width; i++)
4359 {
4360 if ((int)(*sp) >= num_trans)
4361 *dp-- = 0xff;
4362 else
4363 *dp-- = trans_alpha[*sp];
4364 *dp-- = palette[*sp].blue;
4365 *dp-- = palette[*sp].green;
4366 *dp-- = palette[*sp].red;
4367 sp--;
4368 }
4369 row_info->bit_depth = 8;
4370 row_info->pixel_depth = 32;
4371 row_info->rowbytes = row_width * 4;
4372 row_info->color_type = 6;
4373 row_info->channels = 4;
4374 }
4375
4376 else
4377 {
4378 sp = row + (size_t)row_width - 1;
4379 dp = row + (size_t)(row_width * 3) - 1;
4380 i = 0;
4381 #ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
4382 i = png_do_expand_palette_rgb8_neon(png_ptr, row_info, row,
4383 &sp, &dp);
4384 #else
4385 PNG_UNUSED(png_ptr)
4386 #endif
4387
4388 for (; i < row_width; i++)
4389 {
4390 *dp-- = palette[*sp].blue;
4391 *dp-- = palette[*sp].green;
4392 *dp-- = palette[*sp].red;
4393 sp--;
4394 }
4395
4396 row_info->bit_depth = 8;
4397 row_info->pixel_depth = 24;
4398 row_info->rowbytes = row_width * 3;
4399 row_info->color_type = 2;
4400 row_info->channels = 3;
4401 }
4402 }
4403 }
4404 }
4405 }
4406
4407 /* If the bit depth < 8, it is expanded to 8. Also, if the already
4408 * expanded transparency value is supplied, an alpha channel is built.
4409 */
4410 static void
4411 png_do_expand(png_row_infop row_info, png_bytep row,
4412 png_const_color_16p trans_color)
4413 {
4414 int shift, value;
4415 png_bytep sp, dp;
4416 png_uint_32 i;
4417 png_uint_32 row_width=row_info->width;
4418
4419 png_debug(1, "in png_do_expand");
4420
4421 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
4422 {
4423 unsigned int gray = trans_color != NULL ? trans_color->gray : 0;
4424
4425 if (row_info->bit_depth < 8)
4426 {
4427 switch (row_info->bit_depth)
4428 {
4429 case 1:
4430 {
4431 gray = (gray & 0x01) * 0xff;
4432 sp = row + (size_t)((row_width - 1) >> 3);
4433 dp = row + (size_t)row_width - 1;
4434 shift = 7 - (int)((row_width + 7) & 0x07);
4435 for (i = 0; i < row_width; i++)
4436 {
4437 if ((*sp >> shift) & 0x01)
4438 *dp = 0xff;
4439
4440 else
4441 *dp = 0;
4442
4443 if (shift == 7)
4444 {
4445 shift = 0;
4446 sp--;
4447 }
4448
4449 else
4450 shift++;
4451
4452 dp--;
4453 }
4454 break;
4455 }
4456
4457 case 2:
4458 {
4459 gray = (gray & 0x03) * 0x55;
4460 sp = row + (size_t)((row_width - 1) >> 2);
4461 dp = row + (size_t)row_width - 1;
4462 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4463 for (i = 0; i < row_width; i++)
4464 {
4465 value = (*sp >> shift) & 0x03;
4466 *dp = (png_byte)(value | (value << 2) | (value << 4) |
4467 (value << 6));
4468 if (shift == 6)
4469 {
4470 shift = 0;
4471 sp--;
4472 }
4473
4474 else
4475 shift += 2;
4476
4477 dp--;
4478 }
4479 break;
4480 }
4481
4482 case 4:
4483 {
4484 gray = (gray & 0x0f) * 0x11;
4485 sp = row + (size_t)((row_width - 1) >> 1);
4486 dp = row + (size_t)row_width - 1;
4487 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
4488 for (i = 0; i < row_width; i++)
4489 {
4490 value = (*sp >> shift) & 0x0f;
4491 *dp = (png_byte)(value | (value << 4));
4492 if (shift == 4)
4493 {
4494 shift = 0;
4495 sp--;
4496 }
4497
4498 else
4499 shift = 4;
4500
4501 dp--;
4502 }
4503 break;
4504 }
4505
4506 default:
4507 break;
4508 }
4509
4510 row_info->bit_depth = 8;
4511 row_info->pixel_depth = 8;
4512 row_info->rowbytes = row_width;
4513 }
4514
4515 if (trans_color != NULL)
4516 {
4517 if (row_info->bit_depth == 8)
4518 {
4519 gray = gray & 0xff;
4520 sp = row + (size_t)row_width - 1;
4521 dp = row + ((size_t)row_width << 1) - 1;
4522
4523 for (i = 0; i < row_width; i++)
4524 {
4525 if ((*sp & 0xffU) == gray)
4526 *dp-- = 0;
4527
4528 else
4529 *dp-- = 0xff;
4530
4531 *dp-- = *sp--;
4532 }
4533 }
4534
4535 else if (row_info->bit_depth == 16)
4536 {
4537 unsigned int gray_high = (gray >> 8) & 0xff;
4538 unsigned int gray_low = gray & 0xff;
4539 sp = row + row_info->rowbytes - 1;
4540 dp = row + (row_info->rowbytes << 1) - 1;
4541 for (i = 0; i < row_width; i++)
4542 {
4543 if ((*(sp - 1) & 0xffU) == gray_high &&
4544 (*(sp) & 0xffU) == gray_low)
4545 {
4546 *dp-- = 0;
4547 *dp-- = 0;
4548 }
4549
4550 else
4551 {
4552 *dp-- = 0xff;
4553 *dp-- = 0xff;
4554 }
4555
4556 *dp-- = *sp--;
4557 *dp-- = *sp--;
4558 }
4559 }
4560
4561 row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
4562 row_info->channels = 2;
4563 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
4564 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
4565 row_width);
4566 }
4567 }
4568 else if (row_info->color_type == PNG_COLOR_TYPE_RGB &&
4569 trans_color != NULL)
4570 {
4571 if (row_info->bit_depth == 8)
4572 {
4573 png_byte red = (png_byte)(trans_color->red & 0xff);
4574 png_byte green = (png_byte)(trans_color->green & 0xff);
4575 png_byte blue = (png_byte)(trans_color->blue & 0xff);
4576 sp = row + (size_t)row_info->rowbytes - 1;
4577 dp = row + ((size_t)row_width << 2) - 1;
4578 for (i = 0; i < row_width; i++)
4579 {
4580 if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
4581 *dp-- = 0;
4582
4583 else
4584 *dp-- = 0xff;
4585
4586 *dp-- = *sp--;
4587 *dp-- = *sp--;
4588 *dp-- = *sp--;
4589 }
4590 }
4591 else if (row_info->bit_depth == 16)
4592 {
4593 png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff);
4594 png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff);
4595 png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff);
4596 png_byte red_low = (png_byte)(trans_color->red & 0xff);
4597 png_byte green_low = (png_byte)(trans_color->green & 0xff);
4598 png_byte blue_low = (png_byte)(trans_color->blue & 0xff);
4599 sp = row + row_info->rowbytes - 1;
4600 dp = row + ((size_t)row_width << 3) - 1;
4601 for (i = 0; i < row_width; i++)
4602 {
4603 if (*(sp - 5) == red_high &&
4604 *(sp - 4) == red_low &&
4605 *(sp - 3) == green_high &&
4606 *(sp - 2) == green_low &&
4607 *(sp - 1) == blue_high &&
4608 *(sp ) == blue_low)
4609 {
4610 *dp-- = 0;
4611 *dp-- = 0;
4612 }
4613
4614 else
4615 {
4616 *dp-- = 0xff;
4617 *dp-- = 0xff;
4618 }
4619
4620 *dp-- = *sp--;
4621 *dp-- = *sp--;
4622 *dp-- = *sp--;
4623 *dp-- = *sp--;
4624 *dp-- = *sp--;
4625 *dp-- = *sp--;
4626 }
4627 }
4628 row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
4629 row_info->channels = 4;
4630 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
4631 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4632 }
4633 }
4634 #endif
4635
4636 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4637 /* If the bit depth is 8 and the color type is not a palette type expand the
4638 * whole row to 16 bits. Has no effect otherwise.
4639 */
4640 static void
4641 png_do_expand_16(png_row_infop row_info, png_bytep row)
4642 {
4643 if (row_info->bit_depth == 8 &&
4644 row_info->color_type != PNG_COLOR_TYPE_PALETTE)
4645 {
4646 /* The row have a sequence of bytes containing [0..255] and we need
4647 * to turn it into another row containing [0..65535], to do this we
4648 * calculate:
4649 *
4650 * (input / 255) * 65535
4651 *
4652 * Which happens to be exactly input * 257 and this can be achieved
4653 * simply by byte replication in place (copying backwards).
4654 */
4655 png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */
4656 png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */
4657 while (dp > sp)
4658 {
4659 dp[-2] = dp[-1] = *--sp; dp -= 2;
4660 }
4661
4662 row_info->rowbytes *= 2;
4663 row_info->bit_depth = 16;
4664 row_info->pixel_depth = (png_byte)(row_info->channels * 16);
4665 }
4666 }
4667 #endif
4668
4669 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4670 static void
4671 png_do_quantize(png_row_infop row_info, png_bytep row,
4672 png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
4673 {
4674 png_bytep sp, dp;
4675 png_uint_32 i;
4676 png_uint_32 row_width=row_info->width;
4677
4678 png_debug(1, "in png_do_quantize");
4679
4680 if (row_info->bit_depth == 8)
4681 {
4682 if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup)
4683 {
4684 int r, g, b, p;
4685 sp = row;
4686 dp = row;
4687 for (i = 0; i < row_width; i++)
4688 {
4689 r = *sp++;
4690 g = *sp++;
4691 b = *sp++;
4692
4693 /* This looks real messy, but the compiler will reduce
4694 * it down to a reasonable formula. For example, with
4695 * 5 bits per color, we get:
4696 * p = (((r >> 3) & 0x1f) << 10) |
4697 * (((g >> 3) & 0x1f) << 5) |
4698 * ((b >> 3) & 0x1f);
4699 */
4700 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4701 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4702 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4703 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4704 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4705 (PNG_QUANTIZE_BLUE_BITS)) |
4706 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4707 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4708
4709 *dp++ = palette_lookup[p];
4710 }
4711
4712 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4713 row_info->channels = 1;
4714 row_info->pixel_depth = row_info->bit_depth;
4715 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4716 }
4717
4718 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
4719 palette_lookup != NULL)
4720 {
4721 int r, g, b, p;
4722 sp = row;
4723 dp = row;
4724 for (i = 0; i < row_width; i++)
4725 {
4726 r = *sp++;
4727 g = *sp++;
4728 b = *sp++;
4729 sp++;
4730
4731 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4732 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4733 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4734 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4735 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4736 (PNG_QUANTIZE_BLUE_BITS)) |
4737 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4738 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4739
4740 *dp++ = palette_lookup[p];
4741 }
4742
4743 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4744 row_info->channels = 1;
4745 row_info->pixel_depth = row_info->bit_depth;
4746 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4747 }
4748
4749 else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4750 quantize_lookup)
4751 {
4752 sp = row;
4753
4754 for (i = 0; i < row_width; i++, sp++)
4755 {
4756 *sp = quantize_lookup[*sp];
4757 }
4758 }
4759 }
4760 }
4761 #endif /* READ_QUANTIZE */
4762
4763 /* Transform the row. The order of transformations is significant,
4764 * and is very touchy. If you add a transformation, take care to
4765 * decide how it fits in with the other transformations here.
4766 */
4767 void /* PRIVATE */
4768 png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
4769 {
4770 png_debug(1, "in png_do_read_transformations");
4771
4772 if (png_ptr->row_buf == NULL)
4773 {
4774 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
4775 * error is incredibly rare and incredibly easy to debug without this
4776 * information.
4777 */
4778 png_error(png_ptr, "NULL row buffer");
4779 }
4780
4781 /* The following is debugging; prior to 1.5.4 the code was never compiled in;
4782 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
4783 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for
4784 * all transformations, however in practice the ROW_INIT always gets done on
4785 * demand, if necessary.
4786 */
4787 if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
4788 (png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
4789 {
4790 /* Application has failed to call either png_read_start_image() or
4791 * png_read_update_info() after setting transforms that expand pixels.
4792 * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
4793 */
4794 png_error(png_ptr, "Uninitialized row");
4795 }
4796
4797 #ifdef PNG_READ_EXPAND_SUPPORTED
4798 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4799 {
4800 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4801 {
4802 #ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
4803 if ((png_ptr->num_trans > 0) && (png_ptr->bit_depth == 8))
4804 {
4805 if (png_ptr->riffled_palette == NULL)
4806 {
4807 /* Initialize the accelerated palette expansion. */
4808 png_ptr->riffled_palette =
4809 (png_bytep)png_malloc(png_ptr, 256 * 4);
4810 png_riffle_palette_neon(png_ptr);
4811 }
4812 }
4813 #endif
4814 png_do_expand_palette(png_ptr, row_info, png_ptr->row_buf + 1,
4815 png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
4816 }
4817
4818 else
4819 {
4820 if (png_ptr->num_trans != 0 &&
4821 (png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
4822 png_do_expand(row_info, png_ptr->row_buf + 1,
4823 &(png_ptr->trans_color));
4824
4825 else
4826 png_do_expand(row_info, png_ptr->row_buf + 1, NULL);
4827 }
4828 }
4829 #endif
4830
4831 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4832 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4833 (png_ptr->transformations & PNG_COMPOSE) == 0 &&
4834 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4835 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4836 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4837 0 /* at_start == false, because SWAP_ALPHA happens later */);
4838 #endif
4839
4840 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4841 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
4842 {
4843 int rgb_error =
4844 png_do_rgb_to_gray(png_ptr, row_info,
4845 png_ptr->row_buf + 1);
4846
4847 if (rgb_error != 0)
4848 {
4849 png_ptr->rgb_to_gray_status=1;
4850 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4851 PNG_RGB_TO_GRAY_WARN)
4852 png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4853
4854 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4855 PNG_RGB_TO_GRAY_ERR)
4856 png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4857 }
4858 }
4859 #endif
4860
4861 /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
4862 *
4863 * In most cases, the "simple transparency" should be done prior to doing
4864 * gray-to-RGB, or you will have to test 3x as many bytes to check if a
4865 * pixel is transparent. You would also need to make sure that the
4866 * transparency information is upgraded to RGB.
4867 *
4868 * To summarize, the current flow is:
4869 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
4870 * with background "in place" if transparent,
4871 * convert to RGB if necessary
4872 * - Gray + alpha -> composite with gray background and remove alpha bytes,
4873 * convert to RGB if necessary
4874 *
4875 * To support RGB backgrounds for gray images we need:
4876 * - Gray + simple transparency -> convert to RGB + simple transparency,
4877 * compare 3 or 6 bytes and composite with
4878 * background "in place" if transparent
4879 * (3x compare/pixel compared to doing
4880 * composite with gray bkgrnd)
4881 * - Gray + alpha -> convert to RGB + alpha, composite with background and
4882 * remove alpha bytes (3x float
4883 * operations/pixel compared with composite
4884 * on gray background)
4885 *
4886 * Greg's change will do this. The reason it wasn't done before is for
4887 * performance, as this increases the per-pixel operations. If we would check
4888 * in advance if the background was gray or RGB, and position the gray-to-RGB
4889 * transform appropriately, then it would save a lot of work/time.
4890 */
4891
4892 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4893 /* If gray -> RGB, do so now only if background is non-gray; else do later
4894 * for performance reasons
4895 */
4896 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4897 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) == 0)
4898 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4899 #endif
4900
4901 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4902 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4903 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
4904 png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
4905 #endif
4906
4907 #ifdef PNG_READ_GAMMA_SUPPORTED
4908 if ((png_ptr->transformations & PNG_GAMMA) != 0 &&
4909 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4910 /* Because RGB_TO_GRAY does the gamma transform. */
4911 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0 &&
4912 #endif
4913 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4914 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4915 /* Because PNG_COMPOSE does the gamma transform if there is something to
4916 * do (if there is an alpha channel or transparency.)
4917 */
4918 !((png_ptr->transformations & PNG_COMPOSE) != 0 &&
4919 ((png_ptr->num_trans != 0) ||
4920 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)) &&
4921 #endif
4922 /* Because png_init_read_transformations transforms the palette, unless
4923 * RGB_TO_GRAY will do the transform.
4924 */
4925 (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
4926 png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
4927 #endif
4928
4929 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4930 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4931 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
4932 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4933 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4934 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4935 0 /* at_start == false, because SWAP_ALPHA happens later */);
4936 #endif
4937
4938 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4939 if ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
4940 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4941 png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
4942 #endif
4943
4944 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
4945 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
4946 png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
4947 #endif
4948
4949 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
4950 /* There is no harm in doing both of these because only one has any effect,
4951 * by putting the 'scale' option first if the app asks for scale (either by
4952 * calling the API or in a TRANSFORM flag) this is what happens.
4953 */
4954 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
4955 png_do_chop(row_info, png_ptr->row_buf + 1);
4956 #endif
4957
4958 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4959 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
4960 {
4961 png_do_quantize(row_info, png_ptr->row_buf + 1,
4962 png_ptr->palette_lookup, png_ptr->quantize_index);
4963
4964 if (row_info->rowbytes == 0)
4965 png_error(png_ptr, "png_do_quantize returned rowbytes=0");
4966 }
4967 #endif /* READ_QUANTIZE */
4968
4969 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4970 /* Do the expansion now, after all the arithmetic has been done. Notice
4971 * that previous transformations can handle the PNG_EXPAND_16 flag if this
4972 * is efficient (particularly true in the case of gamma correction, where
4973 * better accuracy results faster!)
4974 */
4975 if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
4976 png_do_expand_16(row_info, png_ptr->row_buf + 1);
4977 #endif
4978
4979 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4980 /* NOTE: moved here in 1.5.4 (from much later in this list.) */
4981 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4982 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) != 0)
4983 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4984 #endif
4985
4986 #ifdef PNG_READ_INVERT_SUPPORTED
4987 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
4988 png_do_invert(row_info, png_ptr->row_buf + 1);
4989 #endif
4990
4991 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
4992 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
4993 png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
4994 #endif
4995
4996 #ifdef PNG_READ_SHIFT_SUPPORTED
4997 if ((png_ptr->transformations & PNG_SHIFT) != 0)
4998 png_do_unshift(row_info, png_ptr->row_buf + 1,
4999 &(png_ptr->shift));
5000 #endif
5001
5002 #ifdef PNG_READ_PACK_SUPPORTED
5003 if ((png_ptr->transformations & PNG_PACK) != 0)
5004 png_do_unpack(row_info, png_ptr->row_buf + 1);
5005 #endif
5006
5007 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
5008 /* Added at libpng-1.5.10 */
5009 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
5010 png_ptr->num_palette_max >= 0)
5011 png_do_check_palette_indexes(png_ptr, row_info);
5012 #endif
5013
5014 #ifdef PNG_READ_BGR_SUPPORTED
5015 if ((png_ptr->transformations & PNG_BGR) != 0)
5016 png_do_bgr(row_info, png_ptr->row_buf + 1);
5017 #endif
5018
5019 #ifdef PNG_READ_PACKSWAP_SUPPORTED
5020 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
5021 png_do_packswap(row_info, png_ptr->row_buf + 1);
5022 #endif
5023
5024 #ifdef PNG_READ_FILLER_SUPPORTED
5025 if ((png_ptr->transformations & PNG_FILLER) != 0)
5026 png_do_read_filler(row_info, png_ptr->row_buf + 1,
5027 (png_uint_32)png_ptr->filler, png_ptr->flags);
5028 #endif
5029
5030 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
5031 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
5032 png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
5033 #endif
5034
5035 #ifdef PNG_READ_16BIT_SUPPORTED
5036 #ifdef PNG_READ_SWAP_SUPPORTED
5037 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
5038 png_do_swap(row_info, png_ptr->row_buf + 1);
5039 #endif
5040 #endif
5041
5042 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
5043 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
5044 {
5045 if (png_ptr->read_user_transform_fn != NULL)
5046 (*(png_ptr->read_user_transform_fn)) /* User read transform function */
5047 (png_ptr, /* png_ptr */
5048 row_info, /* row_info: */
5049 /* png_uint_32 width; width of row */
5050 /* size_t rowbytes; number of bytes in row */
5051 /* png_byte color_type; color type of pixels */
5052 /* png_byte bit_depth; bit depth of samples */
5053 /* png_byte channels; number of channels (1-4) */
5054 /* png_byte pixel_depth; bits per pixel (depth*channels) */
5055 png_ptr->row_buf + 1); /* start of pixel data for row */
5056 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
5057 if (png_ptr->user_transform_depth != 0)
5058 row_info->bit_depth = png_ptr->user_transform_depth;
5059
5060 if (png_ptr->user_transform_channels != 0)
5061 row_info->channels = png_ptr->user_transform_channels;
5062 #endif
5063 row_info->pixel_depth = (png_byte)(row_info->bit_depth *
5064 row_info->channels);
5065
5066 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
5067 }
5068 #endif
5069 }
5070
5071 #endif /* READ_TRANSFORMS */
5072 #endif /* READ */