2 /* pngrtran.c - transforms the data in a row for PNG readers
4 * Last changed in libpng 1.6.17 [March 26, 2015]
5 * Copyright (c) 1998-2015 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
13 * This file contains functions optionally called by an application
14 * in order to tell libpng how to handle data when reading a PNG.
15 * Transformations that are used in both reading and writing are
21 #ifdef PNG_READ_SUPPORTED
23 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
25 png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
27 png_debug(1, "in png_set_crc_action");
32 /* Tell libpng how we react to CRC errors in critical chunks */
35 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
38 case PNG_CRC_WARN_USE: /* Warn/use data */
39 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
40 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
43 case PNG_CRC_QUIET_USE: /* Quiet/use data */
44 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
45 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
46 PNG_FLAG_CRC_CRITICAL_IGNORE;
49 case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */
51 "Can't discard critical data on CRC error");
52 case PNG_CRC_ERROR_QUIT: /* Error/quit */
56 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
60 /* Tell libpng how we react to CRC errors in ancillary chunks */
63 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
66 case PNG_CRC_WARN_USE: /* Warn/use data */
67 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
68 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
71 case PNG_CRC_QUIET_USE: /* Quiet/use data */
72 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
73 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
74 PNG_FLAG_CRC_ANCILLARY_NOWARN;
77 case PNG_CRC_ERROR_QUIT: /* Error/quit */
78 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
79 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
82 case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
86 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
91 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
92 /* Is it OK to set a transformation now? Only if png_start_read_image or
93 * png_read_update_info have not been called. It is not necessary for the IHDR
94 * to have been read in all cases; the need_IHDR parameter allows for this
98 png_rtran_ok(png_structrp png_ptr, int need_IHDR)
102 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
103 png_app_error(png_ptr,
104 "invalid after png_start_read_image or png_read_update_info");
106 else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
107 png_app_error(png_ptr, "invalid before the PNG header has been read");
111 /* Turn on failure to initialize correctly for all transforms. */
112 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
118 return 0; /* no png_error possible! */
122 #ifdef PNG_READ_BACKGROUND_SUPPORTED
123 /* Handle alpha and tRNS via a background color */
125 png_set_background_fixed(png_structrp png_ptr,
126 png_const_color_16p background_color, int background_gamma_code,
127 int need_expand, png_fixed_point background_gamma)
129 png_debug(1, "in png_set_background_fixed");
131 if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL)
134 if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
136 png_warning(png_ptr, "Application must supply a known background gamma");
140 png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
141 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
142 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
144 png_ptr->background = *background_color;
145 png_ptr->background_gamma = background_gamma;
146 png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
147 if (need_expand != 0)
148 png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
150 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
153 # ifdef PNG_FLOATING_POINT_SUPPORTED
155 png_set_background(png_structrp png_ptr,
156 png_const_color_16p background_color, int background_gamma_code,
157 int need_expand, double background_gamma)
159 png_set_background_fixed(png_ptr, background_color, background_gamma_code,
160 need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
162 # endif /* FLOATING_POINT */
163 #endif /* READ_BACKGROUND */
165 /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
166 * one that pngrtran does first (scale) happens. This is necessary to allow the
167 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
169 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
171 png_set_scale_16(png_structrp png_ptr)
173 png_debug(1, "in png_set_scale_16");
175 if (png_rtran_ok(png_ptr, 0) == 0)
178 png_ptr->transformations |= PNG_SCALE_16_TO_8;
182 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
183 /* Chop 16-bit depth files to 8-bit depth */
185 png_set_strip_16(png_structrp png_ptr)
187 png_debug(1, "in png_set_strip_16");
189 if (png_rtran_ok(png_ptr, 0) == 0)
192 png_ptr->transformations |= PNG_16_TO_8;
196 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
198 png_set_strip_alpha(png_structrp png_ptr)
200 png_debug(1, "in png_set_strip_alpha");
202 if (png_rtran_ok(png_ptr, 0) == 0)
205 png_ptr->transformations |= PNG_STRIP_ALPHA;
209 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
210 static png_fixed_point
211 translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
214 /* Check for flag values. The main reason for having the old Mac value as a
215 * flag is that it is pretty near impossible to work out what the correct
216 * value is from Apple documentation - a working Mac system is needed to
217 * discover the value!
219 if (output_gamma == PNG_DEFAULT_sRGB ||
220 output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
222 /* If there is no sRGB support this just sets the gamma to the standard
223 * sRGB value. (This is a side effect of using this function!)
225 # ifdef PNG_READ_sRGB_SUPPORTED
226 png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
231 output_gamma = PNG_GAMMA_sRGB;
233 output_gamma = PNG_GAMMA_sRGB_INVERSE;
236 else if (output_gamma == PNG_GAMMA_MAC_18 ||
237 output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
240 output_gamma = PNG_GAMMA_MAC_OLD;
242 output_gamma = PNG_GAMMA_MAC_INVERSE;
248 # ifdef PNG_FLOATING_POINT_SUPPORTED
249 static png_fixed_point
250 convert_gamma_value(png_structrp png_ptr, double output_gamma)
252 /* The following silently ignores cases where fixed point (times 100,000)
253 * gamma values are passed to the floating point API. This is safe and it
254 * means the fixed point constants work just fine with the floating point
255 * API. The alternative would just lead to undetected errors and spurious
256 * bug reports. Negative values fail inside the _fixed API unless they
257 * correspond to the flag values.
259 if (output_gamma > 0 && output_gamma < 128)
260 output_gamma *= PNG_FP_1;
262 /* This preserves -1 and -2 exactly: */
263 output_gamma = floor(output_gamma + .5);
265 if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
266 png_fixed_error(png_ptr, "gamma value");
268 return (png_fixed_point)output_gamma;
271 #endif /* READ_ALPHA_MODE || READ_GAMMA */
273 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
275 png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
276 png_fixed_point output_gamma)
279 png_fixed_point file_gamma;
281 png_debug(1, "in png_set_alpha_mode");
283 if (png_rtran_ok(png_ptr, 0) == 0)
286 output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
288 /* Validate the value to ensure it is in a reasonable range. The value
289 * is expected to be 1 or greater, but this range test allows for some
290 * viewing correction values. The intent is to weed out users of this API
291 * who use the inverse of the gamma value accidentally! Since some of these
292 * values are reasonable this may have to be changed.
294 if (output_gamma < 70000 || output_gamma > 300000)
295 png_error(png_ptr, "output gamma out of expected range");
297 /* The default file gamma is the inverse of the output gamma; the output
298 * gamma may be changed below so get the file value first:
300 file_gamma = png_reciprocal(output_gamma);
302 /* There are really 8 possibilities here, composed of any combination
305 * premultiply the color channels
306 * do not encode non-opaque pixels
307 * encode the alpha as well as the color channels
309 * The differences disappear if the input/output ('screen') gamma is 1.0,
310 * because then the encoding is a no-op and there is only the choice of
311 * premultiplying the color channels or not.
313 * png_set_alpha_mode and png_set_background interact because both use
314 * png_compose to do the work. Calling both is only useful when
315 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
316 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
320 case PNG_ALPHA_PNG: /* default: png standard */
321 /* No compose, but it may be set by png_set_background! */
322 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
323 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
326 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
328 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
329 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
330 /* The output is linear: */
331 output_gamma = PNG_FP_1;
334 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
336 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
337 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
338 /* output_gamma records the encoding of opaque pixels! */
341 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
343 png_ptr->transformations |= PNG_ENCODE_ALPHA;
344 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
348 png_error(png_ptr, "invalid alpha mode");
351 /* Only set the default gamma if the file gamma has not been set (this has
352 * the side effect that the gamma in a second call to png_set_alpha_mode will
355 if (png_ptr->colorspace.gamma == 0)
357 png_ptr->colorspace.gamma = file_gamma;
358 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
361 /* But always set the output gamma: */
362 png_ptr->screen_gamma = output_gamma;
364 /* Finally, if pre-multiplying, set the background fields to achieve the
369 /* And obtain alpha pre-multiplication by composing on black: */
370 memset(&png_ptr->background, 0, (sizeof png_ptr->background));
371 png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
372 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
373 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
375 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
377 "conflicting calls to set alpha mode and background");
379 png_ptr->transformations |= PNG_COMPOSE;
383 # ifdef PNG_FLOATING_POINT_SUPPORTED
385 png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
387 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
393 #ifdef PNG_READ_QUANTIZE_SUPPORTED
394 /* Dither file to 8-bit. Supply a palette, the current number
395 * of elements in the palette, the maximum number of elements
396 * allowed, and a histogram if possible. If the current number
397 * of colors is greater than the maximum number, the palette will be
398 * modified to fit in the maximum number. "full_quantize" indicates
399 * whether we need a quantizing cube set up for RGB images, or if we
400 * simply are reducing the number of colors in a paletted image.
403 typedef struct png_dsort_struct
405 struct png_dsort_struct * next;
409 typedef png_dsort * png_dsortp;
410 typedef png_dsort * * png_dsortpp;
413 png_set_quantize(png_structrp png_ptr, png_colorp palette,
414 int num_palette, int maximum_colors, png_const_uint_16p histogram,
417 png_debug(1, "in png_set_quantize");
419 if (png_rtran_ok(png_ptr, 0) == 0)
422 png_ptr->transformations |= PNG_QUANTIZE;
424 if (full_quantize == 0)
428 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
429 (png_uint_32)(num_palette * (sizeof (png_byte))));
430 for (i = 0; i < num_palette; i++)
431 png_ptr->quantize_index[i] = (png_byte)i;
434 if (num_palette > maximum_colors)
436 if (histogram != NULL)
438 /* This is easy enough, just throw out the least used colors.
439 * Perhaps not the best solution, but good enough.
444 /* Initialize an array to sort colors */
445 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
446 (png_uint_32)(num_palette * (sizeof (png_byte))));
448 /* Initialize the quantize_sort array */
449 for (i = 0; i < num_palette; i++)
450 png_ptr->quantize_sort[i] = (png_byte)i;
452 /* Find the least used palette entries by starting a
453 * bubble sort, and running it until we have sorted
454 * out enough colors. Note that we don't care about
455 * sorting all the colors, just finding which are
459 for (i = num_palette - 1; i >= maximum_colors; i--)
461 int done; /* To stop early if the list is pre-sorted */
465 for (j = 0; j < i; j++)
467 if (histogram[png_ptr->quantize_sort[j]]
468 < histogram[png_ptr->quantize_sort[j + 1]])
472 t = png_ptr->quantize_sort[j];
473 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
474 png_ptr->quantize_sort[j + 1] = t;
483 /* Swap the palette around, and set up a table, if necessary */
484 if (full_quantize != 0)
488 /* Put all the useful colors within the max, but don't
491 for (i = 0; i < maximum_colors; i++)
493 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
497 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
499 palette[i] = palette[j];
507 /* Move all the used colors inside the max limit, and
508 * develop a translation table.
510 for (i = 0; i < maximum_colors; i++)
512 /* Only move the colors we need to */
513 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
519 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
521 tmp_color = palette[j];
522 palette[j] = palette[i];
523 palette[i] = tmp_color;
524 /* Indicate where the color went */
525 png_ptr->quantize_index[j] = (png_byte)i;
526 png_ptr->quantize_index[i] = (png_byte)j;
530 /* Find closest color for those colors we are not using */
531 for (i = 0; i < num_palette; i++)
533 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
535 int min_d, k, min_k, d_index;
537 /* Find the closest color to one we threw out */
538 d_index = png_ptr->quantize_index[i];
539 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
540 for (k = 1, min_k = 0; k < maximum_colors; k++)
544 d = PNG_COLOR_DIST(palette[d_index], palette[k]);
552 /* Point to closest color */
553 png_ptr->quantize_index[i] = (png_byte)min_k;
557 png_free(png_ptr, png_ptr->quantize_sort);
558 png_ptr->quantize_sort = NULL;
562 /* This is much harder to do simply (and quickly). Perhaps
563 * we need to go through a median cut routine, but those
564 * don't always behave themselves with only a few colors
565 * as input. So we will just find the closest two colors,
566 * and throw out one of them (chosen somewhat randomly).
567 * [We don't understand this at all, so if someone wants to
568 * work on improving it, be our guest - AED, GRP]
578 /* Initialize palette index arrays */
579 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
580 (png_uint_32)(num_palette * (sizeof (png_byte))));
581 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
582 (png_uint_32)(num_palette * (sizeof (png_byte))));
584 /* Initialize the sort array */
585 for (i = 0; i < num_palette; i++)
587 png_ptr->index_to_palette[i] = (png_byte)i;
588 png_ptr->palette_to_index[i] = (png_byte)i;
591 hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
592 (sizeof (png_dsortp))));
594 num_new_palette = num_palette;
596 /* Initial wild guess at how far apart the farthest pixel
597 * pair we will be eliminating will be. Larger
598 * numbers mean more areas will be allocated, Smaller
599 * numbers run the risk of not saving enough data, and
600 * having to do this all over again.
602 * I have not done extensive checking on this number.
606 while (num_new_palette > maximum_colors)
608 for (i = 0; i < num_new_palette - 1; i++)
612 for (j = i + 1; j < num_new_palette; j++)
616 d = PNG_COLOR_DIST(palette[i], palette[j]);
621 t = (png_dsortp)png_malloc_warn(png_ptr,
622 (png_uint_32)(sizeof (png_dsort)));
628 t->left = (png_byte)i;
629 t->right = (png_byte)j;
638 for (i = 0; i <= max_d; i++)
644 for (p = hash[i]; p; p = p->next)
646 if ((int)png_ptr->index_to_palette[p->left]
648 (int)png_ptr->index_to_palette[p->right]
653 if (num_new_palette & 0x01)
665 palette[png_ptr->index_to_palette[j]]
666 = palette[num_new_palette];
667 if (full_quantize == 0)
671 for (k = 0; k < num_palette; k++)
673 if (png_ptr->quantize_index[k] ==
674 png_ptr->index_to_palette[j])
675 png_ptr->quantize_index[k] =
676 png_ptr->index_to_palette[next_j];
678 if ((int)png_ptr->quantize_index[k] ==
680 png_ptr->quantize_index[k] =
681 png_ptr->index_to_palette[j];
685 png_ptr->index_to_palette[png_ptr->palette_to_index
686 [num_new_palette]] = png_ptr->index_to_palette[j];
688 png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
689 = png_ptr->palette_to_index[num_new_palette];
691 png_ptr->index_to_palette[j] =
692 (png_byte)num_new_palette;
694 png_ptr->palette_to_index[num_new_palette] =
697 if (num_new_palette <= maximum_colors)
700 if (num_new_palette <= maximum_colors)
705 for (i = 0; i < 769; i++)
709 png_dsortp p = hash[i];
713 png_free(png_ptr, p);
721 png_free(png_ptr, hash);
722 png_free(png_ptr, png_ptr->palette_to_index);
723 png_free(png_ptr, png_ptr->index_to_palette);
724 png_ptr->palette_to_index = NULL;
725 png_ptr->index_to_palette = NULL;
727 num_palette = maximum_colors;
729 if (png_ptr->palette == NULL)
731 png_ptr->palette = palette;
733 png_ptr->num_palette = (png_uint_16)num_palette;
735 if (full_quantize != 0)
739 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
740 PNG_QUANTIZE_BLUE_BITS;
741 int num_red = (1 << PNG_QUANTIZE_RED_BITS);
742 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
743 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
744 png_size_t num_entries = ((png_size_t)1 << total_bits);
746 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
747 (png_uint_32)(num_entries * (sizeof (png_byte))));
749 distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
750 (sizeof (png_byte))));
752 memset(distance, 0xff, num_entries * (sizeof (png_byte)));
754 for (i = 0; i < num_palette; i++)
757 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
758 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
759 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
761 for (ir = 0; ir < num_red; ir++)
763 /* int dr = abs(ir - r); */
764 int dr = ((ir > r) ? ir - r : r - ir);
765 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
766 PNG_QUANTIZE_GREEN_BITS));
768 for (ig = 0; ig < num_green; ig++)
770 /* int dg = abs(ig - g); */
771 int dg = ((ig > g) ? ig - g : g - ig);
773 int dm = ((dr > dg) ? dr : dg);
774 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
776 for (ib = 0; ib < num_blue; ib++)
778 int d_index = index_g | ib;
779 /* int db = abs(ib - b); */
780 int db = ((ib > b) ? ib - b : b - ib);
781 int dmax = ((dm > db) ? dm : db);
782 int d = dmax + dt + db;
784 if (d < (int)distance[d_index])
786 distance[d_index] = (png_byte)d;
787 png_ptr->palette_lookup[d_index] = (png_byte)i;
794 png_free(png_ptr, distance);
797 #endif /* READ_QUANTIZE */
799 #ifdef PNG_READ_GAMMA_SUPPORTED
801 png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
802 png_fixed_point file_gamma)
804 png_debug(1, "in png_set_gamma_fixed");
806 if (png_rtran_ok(png_ptr, 0) == 0)
809 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
810 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
811 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
813 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
814 * premultiplied alpha support; this actually hides an undocumented feature
815 * of the previous implementation which allowed gamma processing to be
816 * disabled in background handling. There is no evidence (so far) that this
817 * was being used; however, png_set_background itself accepted and must still
818 * accept '0' for the gamma value it takes, because it isn't always used.
820 * Since this is an API change (albeit a very minor one that removes an
821 * undocumented API feature) the following checks were only enabled in
825 png_error(png_ptr, "invalid file gamma in png_set_gamma");
828 png_error(png_ptr, "invalid screen gamma in png_set_gamma");
830 /* Set the gamma values unconditionally - this overrides the value in the PNG
831 * file if a gAMA chunk was present. png_set_alpha_mode provides a
832 * different, easier, way to default the file gamma.
834 png_ptr->colorspace.gamma = file_gamma;
835 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
836 png_ptr->screen_gamma = scrn_gamma;
839 # ifdef PNG_FLOATING_POINT_SUPPORTED
841 png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
843 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
844 convert_gamma_value(png_ptr, file_gamma));
846 # endif /* FLOATING_POINT */
847 #endif /* READ_GAMMA */
849 #ifdef PNG_READ_EXPAND_SUPPORTED
850 /* Expand paletted images to RGB, expand grayscale images of
851 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
855 png_set_expand(png_structrp png_ptr)
857 png_debug(1, "in png_set_expand");
859 if (png_rtran_ok(png_ptr, 0) == 0)
862 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
865 /* GRR 19990627: the following three functions currently are identical
866 * to png_set_expand(). However, it is entirely reasonable that someone
867 * might wish to expand an indexed image to RGB but *not* expand a single,
868 * fully transparent palette entry to a full alpha channel--perhaps instead
869 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
870 * the transparent color with a particular RGB value, or drop tRNS entirely.
871 * IOW, a future version of the library may make the transformations flag
872 * a bit more fine-grained, with separate bits for each of these three
875 * More to the point, these functions make it obvious what libpng will be
876 * doing, whereas "expand" can (and does) mean any number of things.
878 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
879 * to expand only the sample depth but not to expand the tRNS to alpha
880 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
883 /* Expand paletted images to RGB. */
885 png_set_palette_to_rgb(png_structrp png_ptr)
887 png_debug(1, "in png_set_palette_to_rgb");
889 if (png_rtran_ok(png_ptr, 0) == 0)
892 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
895 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
897 png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
899 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
901 if (png_rtran_ok(png_ptr, 0) == 0)
904 png_ptr->transformations |= PNG_EXPAND;
907 /* Expand tRNS chunks to alpha channels. */
909 png_set_tRNS_to_alpha(png_structrp png_ptr)
911 png_debug(1, "in png_set_tRNS_to_alpha");
913 if (png_rtran_ok(png_ptr, 0) == 0)
916 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
918 #endif /* READ_EXPAND */
920 #ifdef PNG_READ_EXPAND_16_SUPPORTED
921 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
922 * it may not work correctly.)
925 png_set_expand_16(png_structrp png_ptr)
927 png_debug(1, "in png_set_expand_16");
929 if (png_rtran_ok(png_ptr, 0) == 0)
932 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
936 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
938 png_set_gray_to_rgb(png_structrp png_ptr)
940 png_debug(1, "in png_set_gray_to_rgb");
942 if (png_rtran_ok(png_ptr, 0) == 0)
945 /* Because rgb must be 8 bits or more: */
946 png_set_expand_gray_1_2_4_to_8(png_ptr);
947 png_ptr->transformations |= PNG_GRAY_TO_RGB;
951 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
953 png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
954 png_fixed_point red, png_fixed_point green)
956 png_debug(1, "in png_set_rgb_to_gray");
958 /* Need the IHDR here because of the check on color_type below. */
960 if (png_rtran_ok(png_ptr, 1) == 0)
963 switch (error_action)
965 case PNG_ERROR_ACTION_NONE:
966 png_ptr->transformations |= PNG_RGB_TO_GRAY;
969 case PNG_ERROR_ACTION_WARN:
970 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
973 case PNG_ERROR_ACTION_ERROR:
974 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
978 png_error(png_ptr, "invalid error action to rgb_to_gray");
982 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
983 #ifdef PNG_READ_EXPAND_SUPPORTED
984 png_ptr->transformations |= PNG_EXPAND;
987 /* Make this an error in 1.6 because otherwise the application may assume
988 * that it just worked and get a memory overwrite.
991 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
993 /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
997 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
999 png_uint_16 red_int, green_int;
1001 /* NOTE: this calculation does not round, but this behavior is retained
1002 * for consistency; the inaccuracy is very small. The code here always
1003 * overwrites the coefficients, regardless of whether they have been
1004 * defaulted or set already.
1006 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
1007 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
1009 png_ptr->rgb_to_gray_red_coeff = red_int;
1010 png_ptr->rgb_to_gray_green_coeff = green_int;
1011 png_ptr->rgb_to_gray_coefficients_set = 1;
1016 if (red >= 0 && green >= 0)
1017 png_app_warning(png_ptr,
1018 "ignoring out of range rgb_to_gray coefficients");
1020 /* Use the defaults, from the cHRM chunk if set, else the historical
1021 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
1022 * png_do_rgb_to_gray for more discussion of the values. In this case
1023 * the coefficients are not marked as 'set' and are not overwritten if
1024 * something has already provided a default.
1026 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
1027 png_ptr->rgb_to_gray_green_coeff == 0)
1029 png_ptr->rgb_to_gray_red_coeff = 6968;
1030 png_ptr->rgb_to_gray_green_coeff = 23434;
1031 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1037 #ifdef PNG_FLOATING_POINT_SUPPORTED
1038 /* Convert a RGB image to a grayscale of the same width. This allows us,
1039 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1043 png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
1046 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1047 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
1048 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
1050 #endif /* FLOATING POINT */
1052 #endif /* RGB_TO_GRAY */
1054 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1055 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1057 png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1058 read_user_transform_fn)
1060 png_debug(1, "in png_set_read_user_transform_fn");
1062 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1063 png_ptr->transformations |= PNG_USER_TRANSFORM;
1064 png_ptr->read_user_transform_fn = read_user_transform_fn;
1069 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1070 #ifdef PNG_READ_GAMMA_SUPPORTED
1071 /* In the case of gamma transformations only do transformations on images where
1072 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1073 * slows things down slightly, and also needlessly introduces small errors.
1075 static int /* PRIVATE */
1076 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
1078 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1079 * correction as a difference of the overall transform from 1.0
1081 * We want to compare the threshold with s*f - 1, if we get
1082 * overflow here it is because of wacky gamma values so we
1083 * turn on processing anyway.
1085 png_fixed_point gtest;
1086 return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) ||
1087 png_gamma_significant(gtest);
1091 /* Initialize everything needed for the read. This includes modifying
1095 /* For the moment 'png_init_palette_transformations' and
1096 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1097 * The intent is that these two routines should have palette or rgb operations
1098 * extracted from 'png_init_read_transformations'.
1100 static void /* PRIVATE */
1101 png_init_palette_transformations(png_structrp png_ptr)
1103 /* Called to handle the (input) palette case. In png_do_read_transformations
1104 * the first step is to expand the palette if requested, so this code must
1105 * take care to only make changes that are invariant with respect to the
1106 * palette expansion, or only do them if there is no expansion.
1108 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1111 int input_has_alpha = 0;
1112 int input_has_transparency = 0;
1114 if (png_ptr->num_trans > 0)
1118 /* Ignore if all the entries are opaque (unlikely!) */
1119 for (i=0; i<png_ptr->num_trans; ++i)
1121 if (png_ptr->trans_alpha[i] == 255)
1123 else if (png_ptr->trans_alpha[i] == 0)
1124 input_has_transparency = 1;
1127 input_has_transparency = 1;
1128 input_has_alpha = 1;
1134 /* If no alpha we can optimize. */
1135 if (input_has_alpha == 0)
1137 /* Any alpha means background and associative alpha processing is
1138 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1139 * and ENCODE_ALPHA are irrelevant.
1141 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1142 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1144 if (input_has_transparency == 0)
1145 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1148 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1149 /* png_set_background handling - deals with the complexity of whether the
1150 * background color is in the file format or the screen format in the case
1151 * where an 'expand' will happen.
1154 /* The following code cannot be entered in the alpha pre-multiplication case
1155 * because PNG_BACKGROUND_EXPAND is cancelled below.
1157 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1158 (png_ptr->transformations & PNG_EXPAND) != 0)
1161 png_ptr->background.red =
1162 png_ptr->palette[png_ptr->background.index].red;
1163 png_ptr->background.green =
1164 png_ptr->palette[png_ptr->background.index].green;
1165 png_ptr->background.blue =
1166 png_ptr->palette[png_ptr->background.index].blue;
1168 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1169 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
1171 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1173 /* Invert the alpha channel (in tRNS) unless the pixels are
1174 * going to be expanded, in which case leave it for later
1176 int i, istop = png_ptr->num_trans;
1178 for (i=0; i<istop; i++)
1179 png_ptr->trans_alpha[i] = (png_byte)(255 -
1180 png_ptr->trans_alpha[i]);
1183 #endif /* READ_INVERT_ALPHA */
1185 } /* background expand and (therefore) no alpha association. */
1186 #endif /* READ_EXPAND && READ_BACKGROUND */
1189 static void /* PRIVATE */
1190 png_init_rgb_transformations(png_structrp png_ptr)
1192 /* Added to libpng-1.5.4: check the color type to determine whether there
1193 * is any alpha or transparency in the image and simply cancel the
1194 * background and alpha mode stuff if there isn't.
1196 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
1197 int input_has_transparency = png_ptr->num_trans > 0;
1199 /* If no alpha we can optimize. */
1200 if (input_has_alpha == 0)
1202 /* Any alpha means background and associative alpha processing is
1203 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1204 * and ENCODE_ALPHA are irrelevant.
1206 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1207 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1208 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1211 if (input_has_transparency == 0)
1212 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1215 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1216 /* png_set_background handling - deals with the complexity of whether the
1217 * background color is in the file format or the screen format in the case
1218 * where an 'expand' will happen.
1221 /* The following code cannot be entered in the alpha pre-multiplication case
1222 * because PNG_BACKGROUND_EXPAND is cancelled below.
1224 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1225 (png_ptr->transformations & PNG_EXPAND) != 0 &&
1226 (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1227 /* i.e., GRAY or GRAY_ALPHA */
1230 /* Expand background and tRNS chunks */
1231 int gray = png_ptr->background.gray;
1232 int trans_gray = png_ptr->trans_color.gray;
1234 switch (png_ptr->bit_depth)
1254 /* FALL THROUGH (Already 8 bits) */
1257 /* Already a full 16 bits */
1261 png_ptr->background.red = png_ptr->background.green =
1262 png_ptr->background.blue = (png_uint_16)gray;
1264 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1266 png_ptr->trans_color.red = png_ptr->trans_color.green =
1267 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
1270 } /* background expand and (therefore) no alpha association. */
1271 #endif /* READ_EXPAND && READ_BACKGROUND */
1275 png_init_read_transformations(png_structrp png_ptr)
1277 png_debug(1, "in png_init_read_transformations");
1279 /* This internal function is called from png_read_start_row in pngrutil.c
1280 * and it is called before the 'rowbytes' calculation is done, so the code
1281 * in here can change or update the transformations flags.
1283 * First do updates that do not depend on the details of the PNG image data
1287 #ifdef PNG_READ_GAMMA_SUPPORTED
1288 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1289 * png_set_alpha_mode and this is another source for a default file gamma so
1290 * the test needs to be performed later - here. In addition prior to 1.5.4
1291 * the tests were repeated for the PALETTE color type here - this is no
1292 * longer necessary (and doesn't seem to have been necessary before.)
1295 /* The following temporary indicates if overall gamma correction is
1298 int gamma_correction = 0;
1300 if (png_ptr->colorspace.gamma != 0) /* has been set */
1302 if (png_ptr->screen_gamma != 0) /* screen set too */
1303 gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
1304 png_ptr->screen_gamma);
1307 /* Assume the output matches the input; a long time default behavior
1308 * of libpng, although the standard has nothing to say about this.
1310 png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
1313 else if (png_ptr->screen_gamma != 0)
1314 /* The converse - assume the file matches the screen, note that this
1315 * perhaps undesireable default can (from 1.5.4) be changed by calling
1316 * png_set_alpha_mode (even if the alpha handling mode isn't required
1317 * or isn't changed from the default.)
1319 png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
1321 else /* neither are set */
1322 /* Just in case the following prevents any processing - file and screen
1323 * are both assumed to be linear and there is no way to introduce a
1324 * third gamma value other than png_set_background with 'UNIQUE', and,
1327 png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
1329 /* We have a gamma value now. */
1330 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
1332 /* Now turn the gamma transformation on or off as appropriate. Notice
1333 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1334 * composition may independently cause gamma correction because it needs
1335 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1336 * hasn't been specified.) In any case this flag may get turned off in
1337 * the code immediately below if the transform can be handled outside the
1340 if (gamma_correction != 0)
1341 png_ptr->transformations |= PNG_GAMMA;
1344 png_ptr->transformations &= ~PNG_GAMMA;
1348 /* Certain transformations have the effect of preventing other
1349 * transformations that happen afterward in png_do_read_transformations;
1350 * resolve the interdependencies here. From the code of
1351 * png_do_read_transformations the order is:
1353 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1354 * 2) PNG_STRIP_ALPHA (if no compose)
1355 * 3) PNG_RGB_TO_GRAY
1356 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1359 * 7) PNG_STRIP_ALPHA (if compose)
1360 * 8) PNG_ENCODE_ALPHA
1361 * 9) PNG_SCALE_16_TO_8
1363 * 11) PNG_QUANTIZE (converts to palette)
1365 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1366 * 14) PNG_INVERT_MONO
1367 * 15) PNG_INVERT_ALPHA
1372 * 20) PNG_FILLER (includes PNG_ADD_ALPHA)
1373 * 21) PNG_SWAP_ALPHA
1374 * 22) PNG_SWAP_BYTES
1375 * 23) PNG_USER_TRANSFORM [must be last]
1377 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1378 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
1379 (png_ptr->transformations & PNG_COMPOSE) == 0)
1381 /* Stripping the alpha channel happens immediately after the 'expand'
1382 * transformations, before all other transformation, so it cancels out
1383 * the alpha handling. It has the side effect negating the effect of
1384 * PNG_EXPAND_tRNS too:
1386 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
1388 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1390 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1391 * so transparency information would remain just so long as it wasn't
1392 * expanded. This produces unexpected API changes if the set of things
1393 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1394 * documentation - which says ask for what you want, accept what you
1395 * get.) This makes the behavior consistent from 1.5.4:
1397 png_ptr->num_trans = 0;
1399 #endif /* STRIP_ALPHA supported, no COMPOSE */
1401 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1402 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1403 * settings will have no effect.
1405 if (png_gamma_significant(png_ptr->screen_gamma) == 0)
1407 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1408 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1412 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1413 /* Make sure the coefficients for the rgb to gray conversion are set
1416 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1417 png_colorspace_set_rgb_coefficients(png_ptr);
1420 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1421 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1422 /* Detect gray background and attempt to enable optimization for
1423 * gray --> RGB case.
1425 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1426 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1427 * background color might actually be gray yet not be flagged as such.
1428 * This is not a problem for the current code, which uses
1429 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1430 * png_do_gray_to_rgb() transformation.
1432 * TODO: this code needs to be revised to avoid the complexity and
1433 * interdependencies. The color type of the background should be recorded in
1434 * png_set_background, along with the bit depth, then the code has a record
1435 * of exactly what color space the background is currently in.
1437 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0)
1439 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1440 * the file was grayscale the background value is gray.
1442 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1443 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1446 else if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1448 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1449 * so the color is in the color space of the output or png_set_alpha_mode
1450 * was called and the color is black. Ignore RGB_TO_GRAY because that
1451 * happens before GRAY_TO_RGB.
1453 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
1455 if (png_ptr->background.red == png_ptr->background.green &&
1456 png_ptr->background.red == png_ptr->background.blue)
1458 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1459 png_ptr->background.gray = png_ptr->background.red;
1463 #endif /* READ_EXPAND && READ_BACKGROUND */
1464 #endif /* READ_GRAY_TO_RGB */
1466 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1467 * can be performed directly on the palette, and some (such as rgb to gray)
1468 * can be optimized inside the palette. This is particularly true of the
1469 * composite (background and alpha) stuff, which can be pretty much all done
1470 * in the palette even if the result is expanded to RGB or gray afterward.
1472 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1473 * earlier and the palette stuff is actually handled on the first row. This
1474 * leads to the reported bug that the palette returned by png_get_PLTE is not
1477 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1478 png_init_palette_transformations(png_ptr);
1481 png_init_rgb_transformations(png_ptr);
1483 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1484 defined(PNG_READ_EXPAND_16_SUPPORTED)
1485 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
1486 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1487 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1488 png_ptr->bit_depth != 16)
1490 /* TODO: fix this. Because the expand_16 operation is after the compose
1491 * handling the background color must be 8, not 16, bits deep, but the
1492 * application will supply a 16-bit value so reduce it here.
1494 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1495 * present, so that case is ok (until do_expand_16 is moved.)
1497 * NOTE: this discards the low 16 bits of the user supplied background
1498 * color, but until expand_16 works properly there is no choice!
1500 # define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
1501 CHOP(png_ptr->background.red);
1502 CHOP(png_ptr->background.green);
1503 CHOP(png_ptr->background.blue);
1504 CHOP(png_ptr->background.gray);
1507 #endif /* READ_BACKGROUND && READ_EXPAND_16 */
1509 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1510 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1511 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1512 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 &&
1513 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1514 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1515 png_ptr->bit_depth == 16)
1517 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1518 * component this will also happen after PNG_COMPOSE and so the background
1519 * color must be pre-expanded here.
1521 * TODO: fix this too.
1523 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
1524 png_ptr->background.green =
1525 (png_uint_16)(png_ptr->background.green * 257);
1526 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
1527 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
1531 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1532 * background support (see the comments in scripts/pnglibconf.dfa), this
1533 * allows pre-multiplication of the alpha channel to be implemented as
1534 * compositing on black. This is probably sub-optimal and has been done in
1535 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1536 * implement the new API quickly, without lots of internal changes.)
1539 #ifdef PNG_READ_GAMMA_SUPPORTED
1540 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1541 /* Includes ALPHA_MODE */
1542 png_ptr->background_1 = png_ptr->background;
1545 /* This needs to change - in the palette image case a whole set of tables are
1546 * built when it would be quicker to just calculate the correct value for
1547 * each palette entry directly. Also, the test is too tricky - why check
1548 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1549 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1550 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1551 * the gamma tables will not be built even if composition is required on a
1552 * gamma encoded value.
1554 * In 1.5.4 this is addressed below by an additional check on the individual
1555 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1558 if ((png_ptr->transformations & PNG_GAMMA) != 0 ||
1559 ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 &&
1560 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1561 png_gamma_significant(png_ptr->screen_gamma) != 0)) ||
1562 ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1563 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1564 png_gamma_significant(png_ptr->screen_gamma) != 0
1565 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1566 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE &&
1567 png_gamma_significant(png_ptr->background_gamma) != 0)
1569 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
1570 png_gamma_significant(png_ptr->screen_gamma) != 0))
1572 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
1574 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1575 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1577 /* Issue a warning about this combination: because RGB_TO_GRAY is
1578 * optimized to do the gamma transform if present yet do_background has
1579 * to do the same thing if both options are set a
1580 * double-gamma-correction happens. This is true in all versions of
1583 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1584 png_warning(png_ptr,
1585 "libpng does not support gamma+background+rgb_to_gray");
1587 if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
1589 /* We don't get to here unless there is a tRNS chunk with non-opaque
1590 * entries - see the checking code at the start of this function.
1592 png_color back, back_1;
1593 png_colorp palette = png_ptr->palette;
1594 int num_palette = png_ptr->num_palette;
1596 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
1599 back.red = png_ptr->gamma_table[png_ptr->background.red];
1600 back.green = png_ptr->gamma_table[png_ptr->background.green];
1601 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
1603 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
1604 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
1605 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
1609 png_fixed_point g, gs;
1611 switch (png_ptr->background_gamma_type)
1613 case PNG_BACKGROUND_GAMMA_SCREEN:
1614 g = (png_ptr->screen_gamma);
1618 case PNG_BACKGROUND_GAMMA_FILE:
1619 g = png_reciprocal(png_ptr->colorspace.gamma);
1620 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1621 png_ptr->screen_gamma);
1624 case PNG_BACKGROUND_GAMMA_UNIQUE:
1625 g = png_reciprocal(png_ptr->background_gamma);
1626 gs = png_reciprocal2(png_ptr->background_gamma,
1627 png_ptr->screen_gamma);
1630 g = PNG_FP_1; /* back_1 */
1631 gs = PNG_FP_1; /* back */
1635 if (png_gamma_significant(gs) != 0)
1637 back.red = png_gamma_8bit_correct(png_ptr->background.red,
1639 back.green = png_gamma_8bit_correct(png_ptr->background.green,
1641 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1647 back.red = (png_byte)png_ptr->background.red;
1648 back.green = (png_byte)png_ptr->background.green;
1649 back.blue = (png_byte)png_ptr->background.blue;
1652 if (png_gamma_significant(g) != 0)
1654 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
1656 back_1.green = png_gamma_8bit_correct(
1657 png_ptr->background.green, g);
1658 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1664 back_1.red = (png_byte)png_ptr->background.red;
1665 back_1.green = (png_byte)png_ptr->background.green;
1666 back_1.blue = (png_byte)png_ptr->background.blue;
1670 for (i = 0; i < num_palette; i++)
1672 if (i < (int)png_ptr->num_trans &&
1673 png_ptr->trans_alpha[i] != 0xff)
1675 if (png_ptr->trans_alpha[i] == 0)
1679 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1683 v = png_ptr->gamma_to_1[palette[i].red];
1684 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
1685 palette[i].red = png_ptr->gamma_from_1[w];
1687 v = png_ptr->gamma_to_1[palette[i].green];
1688 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
1689 palette[i].green = png_ptr->gamma_from_1[w];
1691 v = png_ptr->gamma_to_1[palette[i].blue];
1692 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
1693 palette[i].blue = png_ptr->gamma_from_1[w];
1698 palette[i].red = png_ptr->gamma_table[palette[i].red];
1699 palette[i].green = png_ptr->gamma_table[palette[i].green];
1700 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1704 /* Prevent the transformations being done again.
1706 * NOTE: this is highly dubious; it removes the transformations in
1707 * place. This seems inconsistent with the general treatment of the
1708 * transformations elsewhere.
1710 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
1711 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1713 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1714 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1717 png_fixed_point g = PNG_FP_1; /* Correction to linear */
1718 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
1720 switch (png_ptr->background_gamma_type)
1722 case PNG_BACKGROUND_GAMMA_SCREEN:
1723 g = png_ptr->screen_gamma;
1724 /* gs = PNG_FP_1; */
1727 case PNG_BACKGROUND_GAMMA_FILE:
1728 g = png_reciprocal(png_ptr->colorspace.gamma);
1729 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1730 png_ptr->screen_gamma);
1733 case PNG_BACKGROUND_GAMMA_UNIQUE:
1734 g = png_reciprocal(png_ptr->background_gamma);
1735 gs = png_reciprocal2(png_ptr->background_gamma,
1736 png_ptr->screen_gamma);
1740 png_error(png_ptr, "invalid background gamma type");
1743 g_sig = png_gamma_significant(g);
1744 gs_sig = png_gamma_significant(gs);
1747 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
1748 png_ptr->background.gray, g);
1751 png_ptr->background.gray = png_gamma_correct(png_ptr,
1752 png_ptr->background.gray, gs);
1754 if ((png_ptr->background.red != png_ptr->background.green) ||
1755 (png_ptr->background.red != png_ptr->background.blue) ||
1756 (png_ptr->background.red != png_ptr->background.gray))
1758 /* RGB or RGBA with color background */
1761 png_ptr->background_1.red = png_gamma_correct(png_ptr,
1762 png_ptr->background.red, g);
1764 png_ptr->background_1.green = png_gamma_correct(png_ptr,
1765 png_ptr->background.green, g);
1767 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
1768 png_ptr->background.blue, g);
1773 png_ptr->background.red = png_gamma_correct(png_ptr,
1774 png_ptr->background.red, gs);
1776 png_ptr->background.green = png_gamma_correct(png_ptr,
1777 png_ptr->background.green, gs);
1779 png_ptr->background.blue = png_gamma_correct(png_ptr,
1780 png_ptr->background.blue, gs);
1786 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1787 png_ptr->background_1.red = png_ptr->background_1.green
1788 = png_ptr->background_1.blue = png_ptr->background_1.gray;
1790 png_ptr->background.red = png_ptr->background.green
1791 = png_ptr->background.blue = png_ptr->background.gray;
1794 /* The background is now in screen gamma: */
1795 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
1796 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1797 }/* png_ptr->transformations & PNG_BACKGROUND */
1800 /* Transformation does not include PNG_BACKGROUND */
1801 #endif /* READ_BACKGROUND */
1802 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
1803 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1804 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1805 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
1806 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
1810 png_colorp palette = png_ptr->palette;
1811 int num_palette = png_ptr->num_palette;
1814 /* NOTE: there are other transformations that should probably be in
1817 for (i = 0; i < num_palette; i++)
1819 palette[i].red = png_ptr->gamma_table[palette[i].red];
1820 palette[i].green = png_ptr->gamma_table[palette[i].green];
1821 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1824 /* Done the gamma correction. */
1825 png_ptr->transformations &= ~PNG_GAMMA;
1826 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1828 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1831 #endif /* READ_GAMMA */
1833 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1834 /* No GAMMA transformation (see the hanging else 4 lines above) */
1835 if ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1836 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1839 int istop = (int)png_ptr->num_trans;
1841 png_colorp palette = png_ptr->palette;
1843 back.red = (png_byte)png_ptr->background.red;
1844 back.green = (png_byte)png_ptr->background.green;
1845 back.blue = (png_byte)png_ptr->background.blue;
1847 for (i = 0; i < istop; i++)
1849 if (png_ptr->trans_alpha[i] == 0)
1854 else if (png_ptr->trans_alpha[i] != 0xff)
1856 /* The png_composite() macro is defined in png.h */
1857 png_composite(palette[i].red, palette[i].red,
1858 png_ptr->trans_alpha[i], back.red);
1860 png_composite(palette[i].green, palette[i].green,
1861 png_ptr->trans_alpha[i], back.green);
1863 png_composite(palette[i].blue, palette[i].blue,
1864 png_ptr->trans_alpha[i], back.blue);
1868 png_ptr->transformations &= ~PNG_COMPOSE;
1870 #endif /* READ_BACKGROUND */
1872 #ifdef PNG_READ_SHIFT_SUPPORTED
1873 if ((png_ptr->transformations & PNG_SHIFT) != 0 &&
1874 (png_ptr->transformations & PNG_EXPAND) == 0 &&
1875 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1878 int istop = png_ptr->num_palette;
1879 int shift = 8 - png_ptr->sig_bit.red;
1881 png_ptr->transformations &= ~PNG_SHIFT;
1883 /* significant bits can be in the range 1 to 7 for a meaninful result, if
1884 * the number of significant bits is 0 then no shift is done (this is an
1885 * error condition which is silently ignored.)
1887 if (shift > 0 && shift < 8)
1888 for (i=0; i<istop; ++i)
1890 int component = png_ptr->palette[i].red;
1892 component >>= shift;
1893 png_ptr->palette[i].red = (png_byte)component;
1896 shift = 8 - png_ptr->sig_bit.green;
1897 if (shift > 0 && shift < 8)
1898 for (i=0; i<istop; ++i)
1900 int component = png_ptr->palette[i].green;
1902 component >>= shift;
1903 png_ptr->palette[i].green = (png_byte)component;
1906 shift = 8 - png_ptr->sig_bit.blue;
1907 if (shift > 0 && shift < 8)
1908 for (i=0; i<istop; ++i)
1910 int component = png_ptr->palette[i].blue;
1912 component >>= shift;
1913 png_ptr->palette[i].blue = (png_byte)component;
1916 #endif /* READ_SHIFT */
1919 /* Modify the info structure to reflect the transformations. The
1920 * info should be updated so a PNG file could be written with it,
1921 * assuming the transformations result in valid PNG data.
1924 png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
1926 png_debug(1, "in png_read_transform_info");
1928 #ifdef PNG_READ_EXPAND_SUPPORTED
1929 if ((png_ptr->transformations & PNG_EXPAND) != 0)
1931 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1933 /* This check must match what actually happens in
1934 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1935 * it is all opaque we must do the same (at present it does not.)
1937 if (png_ptr->num_trans > 0)
1938 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
1941 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
1943 info_ptr->bit_depth = 8;
1944 info_ptr->num_trans = 0;
1946 if (png_ptr->palette == NULL)
1947 png_error (png_ptr, "Palette is NULL in indexed image");
1951 if (png_ptr->num_trans != 0)
1953 if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
1954 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
1956 if (info_ptr->bit_depth < 8)
1957 info_ptr->bit_depth = 8;
1959 info_ptr->num_trans = 0;
1964 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
1965 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1966 /* The following is almost certainly wrong unless the background value is in
1969 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1970 info_ptr->background = png_ptr->background;
1973 #ifdef PNG_READ_GAMMA_SUPPORTED
1974 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
1975 * however it seems that the code in png_init_read_transformations, which has
1976 * been called before this from png_read_update_info->png_read_start_row
1977 * sometimes does the gamma transform and cancels the flag.
1979 * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
1980 * the screen_gamma value. The following probably results in weirdness if
1981 * the info_ptr is used by the app after the rows have been read.
1983 info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
1986 if (info_ptr->bit_depth == 16)
1988 # ifdef PNG_READ_16BIT_SUPPORTED
1989 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1990 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
1991 info_ptr->bit_depth = 8;
1994 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1995 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
1996 info_ptr->bit_depth = 8;
2000 /* No 16 bit support: force chopping 16-bit input down to 8, in this case
2001 * the app program can chose if both APIs are available by setting the
2002 * correct scaling to use.
2004 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2005 /* For compatibility with previous versions use the strip method by
2006 * default. This code works because if PNG_SCALE_16_TO_8 is already
2007 * set the code below will do that in preference to the chop.
2009 png_ptr->transformations |= PNG_16_TO_8;
2010 info_ptr->bit_depth = 8;
2013 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2014 png_ptr->transformations |= PNG_SCALE_16_TO_8;
2015 info_ptr->bit_depth = 8;
2018 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
2021 #endif /* !READ_16BIT */
2024 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2025 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
2026 info_ptr->color_type = (png_byte)(info_ptr->color_type |
2027 PNG_COLOR_MASK_COLOR);
2030 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2031 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
2032 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2033 ~PNG_COLOR_MASK_COLOR);
2036 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2037 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
2039 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2040 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
2041 png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8)
2043 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
2048 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2049 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
2050 info_ptr->bit_depth == 8 &&
2051 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
2053 info_ptr->bit_depth = 16;
2057 #ifdef PNG_READ_PACK_SUPPORTED
2058 if ((png_ptr->transformations & PNG_PACK) != 0 &&
2059 (info_ptr->bit_depth < 8))
2060 info_ptr->bit_depth = 8;
2063 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
2064 info_ptr->channels = 1;
2066 else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
2067 info_ptr->channels = 3;
2070 info_ptr->channels = 1;
2072 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2073 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0)
2075 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2076 ~PNG_COLOR_MASK_ALPHA);
2077 info_ptr->num_trans = 0;
2081 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
2082 info_ptr->channels++;
2084 #ifdef PNG_READ_FILLER_SUPPORTED
2085 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2086 if ((png_ptr->transformations & PNG_FILLER) != 0 &&
2087 (info_ptr->color_type == PNG_COLOR_TYPE_RGB ||
2088 info_ptr->color_type == PNG_COLOR_TYPE_GRAY))
2090 info_ptr->channels++;
2091 /* If adding a true alpha channel not just filler */
2092 if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0)
2093 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
2097 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2098 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2099 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
2101 if (info_ptr->bit_depth < png_ptr->user_transform_depth)
2102 info_ptr->bit_depth = png_ptr->user_transform_depth;
2104 if (info_ptr->channels < png_ptr->user_transform_channels)
2105 info_ptr->channels = png_ptr->user_transform_channels;
2109 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
2110 info_ptr->bit_depth);
2112 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
2114 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2115 * check in png_rowbytes that the user buffer won't get overwritten. Note
2116 * that the field is not always set - if png_read_update_info isn't called
2117 * the application has to either not do any transforms or get the calculation
2120 png_ptr->info_rowbytes = info_ptr->rowbytes;
2122 #ifndef PNG_READ_EXPAND_SUPPORTED
2123 if (png_ptr != NULL)
2128 #ifdef PNG_READ_PACK_SUPPORTED
2129 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2130 * without changing the actual values. Thus, if you had a row with
2131 * a bit depth of 1, you would end up with bytes that only contained
2132 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2133 * png_do_shift() after this.
2136 png_do_unpack(png_row_infop row_info, png_bytep row)
2138 png_debug(1, "in png_do_unpack");
2140 if (row_info->bit_depth < 8)
2143 png_uint_32 row_width=row_info->width;
2145 switch (row_info->bit_depth)
2149 png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
2150 png_bytep dp = row + (png_size_t)row_width - 1;
2151 png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
2152 for (i = 0; i < row_width; i++)
2154 *dp = (png_byte)((*sp >> shift) & 0x01);
2173 png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
2174 png_bytep dp = row + (png_size_t)row_width - 1;
2175 png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
2176 for (i = 0; i < row_width; i++)
2178 *dp = (png_byte)((*sp >> shift) & 0x03);
2196 png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
2197 png_bytep dp = row + (png_size_t)row_width - 1;
2198 png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
2199 for (i = 0; i < row_width; i++)
2201 *dp = (png_byte)((*sp >> shift) & 0x0f);
2220 row_info->bit_depth = 8;
2221 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2222 row_info->rowbytes = row_width * row_info->channels;
2227 #ifdef PNG_READ_SHIFT_SUPPORTED
2228 /* Reverse the effects of png_do_shift. This routine merely shifts the
2229 * pixels back to their significant bits values. Thus, if you have
2230 * a row of bit depth 8, but only 5 are significant, this will shift
2231 * the values back to 0 through 31.
2234 png_do_unshift(png_row_infop row_info, png_bytep row,
2235 png_const_color_8p sig_bits)
2239 png_debug(1, "in png_do_unshift");
2241 /* The palette case has already been handled in the _init routine. */
2242 color_type = row_info->color_type;
2244 if (color_type != PNG_COLOR_TYPE_PALETTE)
2248 int bit_depth = row_info->bit_depth;
2250 if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
2252 shift[channels++] = bit_depth - sig_bits->red;
2253 shift[channels++] = bit_depth - sig_bits->green;
2254 shift[channels++] = bit_depth - sig_bits->blue;
2259 shift[channels++] = bit_depth - sig_bits->gray;
2262 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
2264 shift[channels++] = bit_depth - sig_bits->alpha;
2270 for (c = have_shift = 0; c < channels; ++c)
2272 /* A shift of more than the bit depth is an error condition but it
2273 * gets ignored here.
2275 if (shift[c] <= 0 || shift[c] >= bit_depth)
2282 if (have_shift == 0)
2289 /* Must be 1bpp gray: should not be here! */
2294 /* Must be 2bpp gray */
2295 /* assert(channels == 1 && shift[0] == 1) */
2298 png_bytep bp_end = bp + row_info->rowbytes;
2302 int b = (*bp >> 1) & 0x55;
2303 *bp++ = (png_byte)b;
2309 /* Must be 4bpp gray */
2310 /* assert(channels == 1) */
2313 png_bytep bp_end = bp + row_info->rowbytes;
2314 int gray_shift = shift[0];
2315 int mask = 0xf >> gray_shift;
2321 int b = (*bp >> gray_shift) & mask;
2322 *bp++ = (png_byte)b;
2328 /* Single byte components, G, GA, RGB, RGBA */
2331 png_bytep bp_end = bp + row_info->rowbytes;
2336 int b = *bp >> shift[channel];
2337 if (++channel >= channels)
2339 *bp++ = (png_byte)b;
2344 #ifdef PNG_READ_16BIT_SUPPORTED
2346 /* Double byte components, G, GA, RGB, RGBA */
2349 png_bytep bp_end = bp + row_info->rowbytes;
2354 int value = (bp[0] << 8) + bp[1];
2356 value >>= shift[channel];
2357 if (++channel >= channels)
2359 *bp++ = (png_byte)(value >> 8);
2360 *bp++ = (png_byte)value;
2370 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2371 /* Scale rows of bit depth 16 down to 8 accurately */
2373 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
2375 png_debug(1, "in png_do_scale_16_to_8");
2377 if (row_info->bit_depth == 16)
2379 png_bytep sp = row; /* source */
2380 png_bytep dp = row; /* destination */
2381 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2385 /* The input is an array of 16 bit components, these must be scaled to
2386 * 8 bits each. For a 16 bit value V the required value (from the PNG
2387 * specification) is:
2391 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2393 * Represent V as the two byte value vhi.vlo. Make a guess that the
2394 * result is the top byte of V, vhi, then the correction to this value
2397 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2398 * = floor(((vlo-vhi) + 128.5) / 257)
2400 * This can be approximated using integer arithmetic (and a signed
2403 * error = (vlo-vhi+128) >> 8;
2405 * The approximate differs from the exact answer only when (vlo-vhi) is
2406 * 128; it then gives a correction of +1 when the exact correction is
2407 * 0. This gives 128 errors. The exact answer (correct for all 16 bit
2410 * error = (vlo-vhi+128)*65535 >> 24;
2412 * An alternative arithmetic calculation which also gives no errors is:
2414 * (V * 255 + 32895) >> 16
2417 png_int_32 tmp = *sp++; /* must be signed! */
2418 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
2419 *dp++ = (png_byte)tmp;
2422 row_info->bit_depth = 8;
2423 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2424 row_info->rowbytes = row_info->width * row_info->channels;
2429 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2431 /* Simply discard the low byte. This was the default behavior prior
2434 png_do_chop(png_row_infop row_info, png_bytep row)
2436 png_debug(1, "in png_do_chop");
2438 if (row_info->bit_depth == 16)
2440 png_bytep sp = row; /* source */
2441 png_bytep dp = row; /* destination */
2442 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2447 sp += 2; /* skip low byte */
2450 row_info->bit_depth = 8;
2451 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2452 row_info->rowbytes = row_info->width * row_info->channels;
2457 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2459 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
2461 png_debug(1, "in png_do_read_swap_alpha");
2464 png_uint_32 row_width = row_info->width;
2465 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2467 /* This converts from RGBA to ARGB */
2468 if (row_info->bit_depth == 8)
2470 png_bytep sp = row + row_info->rowbytes;
2475 for (i = 0; i < row_width; i++)
2485 #ifdef PNG_READ_16BIT_SUPPORTED
2486 /* This converts from RRGGBBAA to AARRGGBB */
2489 png_bytep sp = row + row_info->rowbytes;
2494 for (i = 0; i < row_width; i++)
2511 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2513 /* This converts from GA to AG */
2514 if (row_info->bit_depth == 8)
2516 png_bytep sp = row + row_info->rowbytes;
2521 for (i = 0; i < row_width; i++)
2529 #ifdef PNG_READ_16BIT_SUPPORTED
2530 /* This converts from GGAA to AAGG */
2533 png_bytep sp = row + row_info->rowbytes;
2538 for (i = 0; i < row_width; i++)
2554 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2556 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
2558 png_uint_32 row_width;
2559 png_debug(1, "in png_do_read_invert_alpha");
2561 row_width = row_info->width;
2562 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2564 if (row_info->bit_depth == 8)
2566 /* This inverts the alpha channel in RGBA */
2567 png_bytep sp = row + row_info->rowbytes;
2571 for (i = 0; i < row_width; i++)
2573 *(--dp) = (png_byte)(255 - *(--sp));
2575 /* This does nothing:
2579 We can replace it with:
2586 #ifdef PNG_READ_16BIT_SUPPORTED
2587 /* This inverts the alpha channel in RRGGBBAA */
2590 png_bytep sp = row + row_info->rowbytes;
2594 for (i = 0; i < row_width; i++)
2596 *(--dp) = (png_byte)(255 - *(--sp));
2597 *(--dp) = (png_byte)(255 - *(--sp));
2599 /* This does nothing:
2606 We can replace it with:
2614 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2616 if (row_info->bit_depth == 8)
2618 /* This inverts the alpha channel in GA */
2619 png_bytep sp = row + row_info->rowbytes;
2623 for (i = 0; i < row_width; i++)
2625 *(--dp) = (png_byte)(255 - *(--sp));
2630 #ifdef PNG_READ_16BIT_SUPPORTED
2633 /* This inverts the alpha channel in GGAA */
2634 png_bytep sp = row + row_info->rowbytes;
2638 for (i = 0; i < row_width; i++)
2640 *(--dp) = (png_byte)(255 - *(--sp));
2641 *(--dp) = (png_byte)(255 - *(--sp));
2655 #ifdef PNG_READ_FILLER_SUPPORTED
2656 /* Add filler channel if we have RGB color */
2658 png_do_read_filler(png_row_infop row_info, png_bytep row,
2659 png_uint_32 filler, png_uint_32 flags)
2662 png_uint_32 row_width = row_info->width;
2664 #ifdef PNG_READ_16BIT_SUPPORTED
2665 png_byte hi_filler = (png_byte)(filler>>8);
2667 png_byte lo_filler = (png_byte)filler;
2669 png_debug(1, "in png_do_read_filler");
2672 row_info->color_type == PNG_COLOR_TYPE_GRAY)
2674 if (row_info->bit_depth == 8)
2676 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2678 /* This changes the data from G to GX */
2679 png_bytep sp = row + (png_size_t)row_width;
2680 png_bytep dp = sp + (png_size_t)row_width;
2681 for (i = 1; i < row_width; i++)
2683 *(--dp) = lo_filler;
2686 *(--dp) = lo_filler;
2687 row_info->channels = 2;
2688 row_info->pixel_depth = 16;
2689 row_info->rowbytes = row_width * 2;
2694 /* This changes the data from G to XG */
2695 png_bytep sp = row + (png_size_t)row_width;
2696 png_bytep dp = sp + (png_size_t)row_width;
2697 for (i = 0; i < row_width; i++)
2700 *(--dp) = lo_filler;
2702 row_info->channels = 2;
2703 row_info->pixel_depth = 16;
2704 row_info->rowbytes = row_width * 2;
2708 #ifdef PNG_READ_16BIT_SUPPORTED
2709 else if (row_info->bit_depth == 16)
2711 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2713 /* This changes the data from GG to GGXX */
2714 png_bytep sp = row + (png_size_t)row_width * 2;
2715 png_bytep dp = sp + (png_size_t)row_width * 2;
2716 for (i = 1; i < row_width; i++)
2718 *(--dp) = lo_filler;
2719 *(--dp) = hi_filler;
2723 *(--dp) = lo_filler;
2724 *(--dp) = hi_filler;
2725 row_info->channels = 2;
2726 row_info->pixel_depth = 32;
2727 row_info->rowbytes = row_width * 4;
2732 /* This changes the data from GG to XXGG */
2733 png_bytep sp = row + (png_size_t)row_width * 2;
2734 png_bytep dp = sp + (png_size_t)row_width * 2;
2735 for (i = 0; i < row_width; i++)
2739 *(--dp) = lo_filler;
2740 *(--dp) = hi_filler;
2742 row_info->channels = 2;
2743 row_info->pixel_depth = 32;
2744 row_info->rowbytes = row_width * 4;
2748 } /* COLOR_TYPE == GRAY */
2749 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
2751 if (row_info->bit_depth == 8)
2753 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2755 /* This changes the data from RGB to RGBX */
2756 png_bytep sp = row + (png_size_t)row_width * 3;
2757 png_bytep dp = sp + (png_size_t)row_width;
2758 for (i = 1; i < row_width; i++)
2760 *(--dp) = lo_filler;
2765 *(--dp) = lo_filler;
2766 row_info->channels = 4;
2767 row_info->pixel_depth = 32;
2768 row_info->rowbytes = row_width * 4;
2773 /* This changes the data from RGB to XRGB */
2774 png_bytep sp = row + (png_size_t)row_width * 3;
2775 png_bytep dp = sp + (png_size_t)row_width;
2776 for (i = 0; i < row_width; i++)
2781 *(--dp) = lo_filler;
2783 row_info->channels = 4;
2784 row_info->pixel_depth = 32;
2785 row_info->rowbytes = row_width * 4;
2789 #ifdef PNG_READ_16BIT_SUPPORTED
2790 else if (row_info->bit_depth == 16)
2792 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2794 /* This changes the data from RRGGBB to RRGGBBXX */
2795 png_bytep sp = row + (png_size_t)row_width * 6;
2796 png_bytep dp = sp + (png_size_t)row_width * 2;
2797 for (i = 1; i < row_width; i++)
2799 *(--dp) = lo_filler;
2800 *(--dp) = hi_filler;
2808 *(--dp) = lo_filler;
2809 *(--dp) = hi_filler;
2810 row_info->channels = 4;
2811 row_info->pixel_depth = 64;
2812 row_info->rowbytes = row_width * 8;
2817 /* This changes the data from RRGGBB to XXRRGGBB */
2818 png_bytep sp = row + (png_size_t)row_width * 6;
2819 png_bytep dp = sp + (png_size_t)row_width * 2;
2820 for (i = 0; i < row_width; i++)
2828 *(--dp) = lo_filler;
2829 *(--dp) = hi_filler;
2832 row_info->channels = 4;
2833 row_info->pixel_depth = 64;
2834 row_info->rowbytes = row_width * 8;
2838 } /* COLOR_TYPE == RGB */
2842 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2843 /* Expand grayscale files to RGB, with or without alpha */
2845 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
2848 png_uint_32 row_width = row_info->width;
2850 png_debug(1, "in png_do_gray_to_rgb");
2852 if (row_info->bit_depth >= 8 &&
2853 (row_info->color_type & PNG_COLOR_MASK_COLOR) == 0)
2855 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
2857 if (row_info->bit_depth == 8)
2859 /* This changes G to RGB */
2860 png_bytep sp = row + (png_size_t)row_width - 1;
2861 png_bytep dp = sp + (png_size_t)row_width * 2;
2862 for (i = 0; i < row_width; i++)
2872 /* This changes GG to RRGGBB */
2873 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2874 png_bytep dp = sp + (png_size_t)row_width * 4;
2875 for (i = 0; i < row_width; i++)
2878 *(dp--) = *(sp - 1);
2880 *(dp--) = *(sp - 1);
2887 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2889 if (row_info->bit_depth == 8)
2891 /* This changes GA to RGBA */
2892 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2893 png_bytep dp = sp + (png_size_t)row_width * 2;
2894 for (i = 0; i < row_width; i++)
2905 /* This changes GGAA to RRGGBBAA */
2906 png_bytep sp = row + (png_size_t)row_width * 4 - 1;
2907 png_bytep dp = sp + (png_size_t)row_width * 4;
2908 for (i = 0; i < row_width; i++)
2913 *(dp--) = *(sp - 1);
2915 *(dp--) = *(sp - 1);
2921 row_info->channels = (png_byte)(row_info->channels + 2);
2922 row_info->color_type |= PNG_COLOR_MASK_COLOR;
2923 row_info->pixel_depth = (png_byte)(row_info->channels *
2924 row_info->bit_depth);
2925 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
2930 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2931 /* Reduce RGB files to grayscale, with or without alpha
2932 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
2933 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
2934 * versions dated 1998 through November 2002 have been archived at
2935 * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
2936 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
2937 * Charles Poynton poynton at poynton.com
2939 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
2941 * which can be expressed with integers as
2943 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
2945 * Poynton's current link (as of January 2003 through July 2011):
2946 * <http://www.poynton.com/notes/colour_and_gamma/>
2947 * has changed the numbers slightly:
2949 * Y = 0.2126*R + 0.7152*G + 0.0722*B
2951 * which can be expressed with integers as
2953 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
2955 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
2956 * end point chromaticities and the D65 white point. Depending on the
2957 * precision used for the D65 white point this produces a variety of different
2958 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
2959 * used (0.3127,0.3290) the Y calculation would be:
2961 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
2963 * While this is correct the rounding results in an overflow for white, because
2964 * the sum of the rounded coefficients is 32769, not 32768. Consequently
2965 * libpng uses, instead, the closest non-overflowing approximation:
2967 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
2969 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
2970 * (including an sRGB chunk) then the chromaticities are used to calculate the
2971 * coefficients. See the chunk handling in pngrutil.c for more information.
2973 * In all cases the calculation is to be done in a linear colorspace. If no
2974 * gamma information is available to correct the encoding of the original RGB
2975 * values this results in an implicit assumption that the original PNG RGB
2976 * values were linear.
2978 * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
2979 * the API takes just red and green coefficients the blue coefficient is
2980 * calculated to make the sum 32768. This will result in different rounding
2981 * to that used above.
2984 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
2989 png_debug(1, "in png_do_rgb_to_gray");
2991 if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
2992 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
2994 PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
2995 PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
2996 PNG_CONST png_uint_32 bc = 32768 - rc - gc;
2997 PNG_CONST png_uint_32 row_width = row_info->width;
2998 PNG_CONST int have_alpha =
2999 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
3001 if (row_info->bit_depth == 8)
3003 #ifdef PNG_READ_GAMMA_SUPPORTED
3004 /* Notice that gamma to/from 1 are not necessarily inverses (if
3005 * there is an overall gamma correction). Prior to 1.5.5 this code
3006 * checked the linearized values for equality; this doesn't match
3007 * the documentation, the original values must be checked.
3009 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
3015 for (i = 0; i < row_width; i++)
3017 png_byte red = *(sp++);
3018 png_byte green = *(sp++);
3019 png_byte blue = *(sp++);
3021 if (red != green || red != blue)
3023 red = png_ptr->gamma_to_1[red];
3024 green = png_ptr->gamma_to_1[green];
3025 blue = png_ptr->gamma_to_1[blue];
3028 *(dp++) = png_ptr->gamma_from_1[
3029 (rc*red + gc*green + bc*blue + 16384)>>15];
3034 /* If there is no overall correction the table will not be
3037 if (png_ptr->gamma_table != NULL)
3038 red = png_ptr->gamma_table[red];
3043 if (have_alpha != 0)
3054 for (i = 0; i < row_width; i++)
3056 png_byte red = *(sp++);
3057 png_byte green = *(sp++);
3058 png_byte blue = *(sp++);
3060 if (red != green || red != blue)
3063 /* NOTE: this is the historical approach which simply
3064 * truncates the results.
3066 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
3072 if (have_alpha != 0)
3078 else /* RGB bit_depth == 16 */
3080 #ifdef PNG_READ_GAMMA_SUPPORTED
3081 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
3087 for (i = 0; i < row_width; i++)
3089 png_uint_16 red, green, blue, w;
3092 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3093 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3094 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3096 if (red == green && red == blue)
3098 if (png_ptr->gamma_16_table != NULL)
3099 w = png_ptr->gamma_16_table[(red & 0xff)
3100 >> png_ptr->gamma_shift][red >> 8];
3108 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red & 0xff)
3109 >> png_ptr->gamma_shift][red>>8];
3110 png_uint_16 green_1 =
3111 png_ptr->gamma_16_to_1[(green & 0xff) >>
3112 png_ptr->gamma_shift][green>>8];
3113 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue & 0xff)
3114 >> png_ptr->gamma_shift][blue>>8];
3115 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
3116 + bc*blue_1 + 16384)>>15);
3117 w = png_ptr->gamma_16_from_1[(gray16 & 0xff) >>
3118 png_ptr->gamma_shift][gray16 >> 8];
3122 *(dp++) = (png_byte)((w>>8) & 0xff);
3123 *(dp++) = (png_byte)(w & 0xff);
3125 if (have_alpha != 0)
3139 for (i = 0; i < row_width; i++)
3141 png_uint_16 red, green, blue, gray16;
3144 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3145 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3146 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3148 if (red != green || red != blue)
3151 /* From 1.5.5 in the 16 bit case do the accurate conversion even
3152 * in the 'fast' case - this is because this is where the code
3153 * ends up when handling linear 16 bit data.
3155 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
3157 *(dp++) = (png_byte)((gray16 >> 8) & 0xff);
3158 *(dp++) = (png_byte)(gray16 & 0xff);
3160 if (have_alpha != 0)
3169 row_info->channels = (png_byte)(row_info->channels - 2);
3170 row_info->color_type = (png_byte)(row_info->color_type &
3171 ~PNG_COLOR_MASK_COLOR);
3172 row_info->pixel_depth = (png_byte)(row_info->channels *
3173 row_info->bit_depth);
3174 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3180 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
3181 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
3182 /* Replace any alpha or transparency with the supplied background color.
3183 * "background" is already in the screen gamma, while "background_1" is
3184 * at a gamma of 1.0. Paletted files have already been taken care of.
3187 png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3189 #ifdef PNG_READ_GAMMA_SUPPORTED
3190 png_const_bytep gamma_table = png_ptr->gamma_table;
3191 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
3192 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
3193 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
3194 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
3195 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
3196 int gamma_shift = png_ptr->gamma_shift;
3197 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
3202 png_uint_32 row_width = row_info->width;
3205 png_debug(1, "in png_do_compose");
3208 switch (row_info->color_type)
3210 case PNG_COLOR_TYPE_GRAY:
3212 switch (row_info->bit_depth)
3218 for (i = 0; i < row_width; i++)
3220 if ((png_uint_16)((*sp >> shift) & 0x01)
3221 == png_ptr->trans_color.gray)
3223 unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
3224 tmp |= png_ptr->background.gray << shift;
3225 *sp = (png_byte)(tmp & 0xff);
3242 #ifdef PNG_READ_GAMMA_SUPPORTED
3243 if (gamma_table != NULL)
3247 for (i = 0; i < row_width; i++)
3249 if ((png_uint_16)((*sp >> shift) & 0x03)
3250 == png_ptr->trans_color.gray)
3252 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3253 tmp |= png_ptr->background.gray << shift;
3254 *sp = (png_byte)(tmp & 0xff);
3259 unsigned int p = (*sp >> shift) & 0x03;
3260 unsigned int g = (gamma_table [p | (p << 2) |
3261 (p << 4) | (p << 6)] >> 6) & 0x03;
3262 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3264 *sp = (png_byte)(tmp & 0xff);
3283 for (i = 0; i < row_width; i++)
3285 if ((png_uint_16)((*sp >> shift) & 0x03)
3286 == png_ptr->trans_color.gray)
3288 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3289 tmp |= png_ptr->background.gray << shift;
3290 *sp = (png_byte)(tmp & 0xff);
3308 #ifdef PNG_READ_GAMMA_SUPPORTED
3309 if (gamma_table != NULL)
3313 for (i = 0; i < row_width; i++)
3315 if ((png_uint_16)((*sp >> shift) & 0x0f)
3316 == png_ptr->trans_color.gray)
3318 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3319 tmp |= png_ptr->background.gray << shift;
3320 *sp = (png_byte)(tmp & 0xff);
3325 unsigned int p = (*sp >> shift) & 0x0f;
3326 unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
3328 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3330 *sp = (png_byte)(tmp & 0xff);
3349 for (i = 0; i < row_width; i++)
3351 if ((png_uint_16)((*sp >> shift) & 0x0f)
3352 == png_ptr->trans_color.gray)
3354 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3355 tmp |= png_ptr->background.gray << shift;
3356 *sp = (png_byte)(tmp & 0xff);
3374 #ifdef PNG_READ_GAMMA_SUPPORTED
3375 if (gamma_table != NULL)
3378 for (i = 0; i < row_width; i++, sp++)
3380 if (*sp == png_ptr->trans_color.gray)
3381 *sp = (png_byte)png_ptr->background.gray;
3384 *sp = gamma_table[*sp];
3391 for (i = 0; i < row_width; i++, sp++)
3393 if (*sp == png_ptr->trans_color.gray)
3394 *sp = (png_byte)png_ptr->background.gray;
3402 #ifdef PNG_READ_GAMMA_SUPPORTED
3403 if (gamma_16 != NULL)
3406 for (i = 0; i < row_width; i++, sp += 2)
3410 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3412 if (v == png_ptr->trans_color.gray)
3414 /* Background is already in screen gamma */
3415 *sp = (png_byte)((png_ptr->background.gray >> 8)
3417 *(sp + 1) = (png_byte)(png_ptr->background.gray
3423 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3424 *sp = (png_byte)((v >> 8) & 0xff);
3425 *(sp + 1) = (png_byte)(v & 0xff);
3433 for (i = 0; i < row_width; i++, sp += 2)
3437 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3439 if (v == png_ptr->trans_color.gray)
3441 *sp = (png_byte)((png_ptr->background.gray >> 8)
3443 *(sp + 1) = (png_byte)(png_ptr->background.gray
3457 case PNG_COLOR_TYPE_RGB:
3459 if (row_info->bit_depth == 8)
3461 #ifdef PNG_READ_GAMMA_SUPPORTED
3462 if (gamma_table != NULL)
3465 for (i = 0; i < row_width; i++, sp += 3)
3467 if (*sp == png_ptr->trans_color.red &&
3468 *(sp + 1) == png_ptr->trans_color.green &&
3469 *(sp + 2) == png_ptr->trans_color.blue)
3471 *sp = (png_byte)png_ptr->background.red;
3472 *(sp + 1) = (png_byte)png_ptr->background.green;
3473 *(sp + 2) = (png_byte)png_ptr->background.blue;
3478 *sp = gamma_table[*sp];
3479 *(sp + 1) = gamma_table[*(sp + 1)];
3480 *(sp + 2) = gamma_table[*(sp + 2)];
3488 for (i = 0; i < row_width; i++, sp += 3)
3490 if (*sp == png_ptr->trans_color.red &&
3491 *(sp + 1) == png_ptr->trans_color.green &&
3492 *(sp + 2) == png_ptr->trans_color.blue)
3494 *sp = (png_byte)png_ptr->background.red;
3495 *(sp + 1) = (png_byte)png_ptr->background.green;
3496 *(sp + 2) = (png_byte)png_ptr->background.blue;
3501 else /* if (row_info->bit_depth == 16) */
3503 #ifdef PNG_READ_GAMMA_SUPPORTED
3504 if (gamma_16 != NULL)
3507 for (i = 0; i < row_width; i++, sp += 6)
3509 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3511 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3514 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3517 if (r == png_ptr->trans_color.red &&
3518 g == png_ptr->trans_color.green &&
3519 b == png_ptr->trans_color.blue)
3521 /* Background is already in screen gamma */
3522 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3523 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3524 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3526 *(sp + 3) = (png_byte)(png_ptr->background.green
3528 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3530 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3535 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3536 *sp = (png_byte)((v >> 8) & 0xff);
3537 *(sp + 1) = (png_byte)(v & 0xff);
3539 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3540 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3541 *(sp + 3) = (png_byte)(v & 0xff);
3543 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3544 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3545 *(sp + 5) = (png_byte)(v & 0xff);
3554 for (i = 0; i < row_width; i++, sp += 6)
3556 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3558 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3561 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3564 if (r == png_ptr->trans_color.red &&
3565 g == png_ptr->trans_color.green &&
3566 b == png_ptr->trans_color.blue)
3568 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3569 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3570 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3572 *(sp + 3) = (png_byte)(png_ptr->background.green
3574 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3576 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3584 case PNG_COLOR_TYPE_GRAY_ALPHA:
3586 if (row_info->bit_depth == 8)
3588 #ifdef PNG_READ_GAMMA_SUPPORTED
3589 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3590 gamma_table != NULL)
3593 for (i = 0; i < row_width; i++, sp += 2)
3595 png_uint_16 a = *(sp + 1);
3598 *sp = gamma_table[*sp];
3602 /* Background is already in screen gamma */
3603 *sp = (png_byte)png_ptr->background.gray;
3610 v = gamma_to_1[*sp];
3611 png_composite(w, v, a, png_ptr->background_1.gray);
3613 w = gamma_from_1[w];
3622 for (i = 0; i < row_width; i++, sp += 2)
3624 png_byte a = *(sp + 1);
3627 *sp = (png_byte)png_ptr->background.gray;
3630 png_composite(*sp, *sp, a, png_ptr->background.gray);
3634 else /* if (png_ptr->bit_depth == 16) */
3636 #ifdef PNG_READ_GAMMA_SUPPORTED
3637 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3638 gamma_16_to_1 != NULL)
3641 for (i = 0; i < row_width; i++, sp += 4)
3643 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3646 if (a == (png_uint_16)0xffff)
3650 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3651 *sp = (png_byte)((v >> 8) & 0xff);
3652 *(sp + 1) = (png_byte)(v & 0xff);
3657 /* Background is already in screen gamma */
3658 *sp = (png_byte)((png_ptr->background.gray >> 8)
3660 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3665 png_uint_16 g, v, w;
3667 g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3668 png_composite_16(v, g, a, png_ptr->background_1.gray);
3672 w = gamma_16_from_1[(v & 0xff) >>
3673 gamma_shift][v >> 8];
3674 *sp = (png_byte)((w >> 8) & 0xff);
3675 *(sp + 1) = (png_byte)(w & 0xff);
3683 for (i = 0; i < row_width; i++, sp += 4)
3685 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3690 *sp = (png_byte)((png_ptr->background.gray >> 8)
3692 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3695 else if (a < 0xffff)
3699 g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3700 png_composite_16(v, g, a, png_ptr->background.gray);
3701 *sp = (png_byte)((v >> 8) & 0xff);
3702 *(sp + 1) = (png_byte)(v & 0xff);
3710 case PNG_COLOR_TYPE_RGB_ALPHA:
3712 if (row_info->bit_depth == 8)
3714 #ifdef PNG_READ_GAMMA_SUPPORTED
3715 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3716 gamma_table != NULL)
3719 for (i = 0; i < row_width; i++, sp += 4)
3721 png_byte a = *(sp + 3);
3725 *sp = gamma_table[*sp];
3726 *(sp + 1) = gamma_table[*(sp + 1)];
3727 *(sp + 2) = gamma_table[*(sp + 2)];
3732 /* Background is already in screen gamma */
3733 *sp = (png_byte)png_ptr->background.red;
3734 *(sp + 1) = (png_byte)png_ptr->background.green;
3735 *(sp + 2) = (png_byte)png_ptr->background.blue;
3742 v = gamma_to_1[*sp];
3743 png_composite(w, v, a, png_ptr->background_1.red);
3744 if (optimize == 0) w = gamma_from_1[w];
3747 v = gamma_to_1[*(sp + 1)];
3748 png_composite(w, v, a, png_ptr->background_1.green);
3749 if (optimize == 0) w = gamma_from_1[w];
3752 v = gamma_to_1[*(sp + 2)];
3753 png_composite(w, v, a, png_ptr->background_1.blue);
3754 if (optimize == 0) w = gamma_from_1[w];
3763 for (i = 0; i < row_width; i++, sp += 4)
3765 png_byte a = *(sp + 3);
3769 *sp = (png_byte)png_ptr->background.red;
3770 *(sp + 1) = (png_byte)png_ptr->background.green;
3771 *(sp + 2) = (png_byte)png_ptr->background.blue;
3776 png_composite(*sp, *sp, a, png_ptr->background.red);
3778 png_composite(*(sp + 1), *(sp + 1), a,
3779 png_ptr->background.green);
3781 png_composite(*(sp + 2), *(sp + 2), a,
3782 png_ptr->background.blue);
3787 else /* if (row_info->bit_depth == 16) */
3789 #ifdef PNG_READ_GAMMA_SUPPORTED
3790 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3791 gamma_16_to_1 != NULL)
3794 for (i = 0; i < row_width; i++, sp += 8)
3796 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3797 << 8) + (png_uint_16)(*(sp + 7)));
3799 if (a == (png_uint_16)0xffff)
3803 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3804 *sp = (png_byte)((v >> 8) & 0xff);
3805 *(sp + 1) = (png_byte)(v & 0xff);
3807 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3808 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3809 *(sp + 3) = (png_byte)(v & 0xff);
3811 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3812 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3813 *(sp + 5) = (png_byte)(v & 0xff);
3818 /* Background is already in screen gamma */
3819 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3820 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3821 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3823 *(sp + 3) = (png_byte)(png_ptr->background.green
3825 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3827 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3834 v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3835 png_composite_16(w, v, a, png_ptr->background_1.red);
3837 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3839 *sp = (png_byte)((w >> 8) & 0xff);
3840 *(sp + 1) = (png_byte)(w & 0xff);
3842 v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
3843 png_composite_16(w, v, a, png_ptr->background_1.green);
3845 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3848 *(sp + 2) = (png_byte)((w >> 8) & 0xff);
3849 *(sp + 3) = (png_byte)(w & 0xff);
3851 v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
3852 png_composite_16(w, v, a, png_ptr->background_1.blue);
3854 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3857 *(sp + 4) = (png_byte)((w >> 8) & 0xff);
3858 *(sp + 5) = (png_byte)(w & 0xff);
3867 for (i = 0; i < row_width; i++, sp += 8)
3869 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3870 << 8) + (png_uint_16)(*(sp + 7)));
3874 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3875 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3876 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3878 *(sp + 3) = (png_byte)(png_ptr->background.green
3880 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3882 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3885 else if (a < 0xffff)
3889 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3890 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3892 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3895 png_composite_16(v, r, a, png_ptr->background.red);
3896 *sp = (png_byte)((v >> 8) & 0xff);
3897 *(sp + 1) = (png_byte)(v & 0xff);
3899 png_composite_16(v, g, a, png_ptr->background.green);
3900 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3901 *(sp + 3) = (png_byte)(v & 0xff);
3903 png_composite_16(v, b, a, png_ptr->background.blue);
3904 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3905 *(sp + 5) = (png_byte)(v & 0xff);
3918 #endif /* READ_BACKGROUND || READ_ALPHA_MODE */
3920 #ifdef PNG_READ_GAMMA_SUPPORTED
3921 /* Gamma correct the image, avoiding the alpha channel. Make sure
3922 * you do this after you deal with the transparency issue on grayscale
3923 * or RGB images. If your bit depth is 8, use gamma_table, if it
3924 * is 16, use gamma_16_table and gamma_shift. Build these with
3925 * build_gamma_table().
3928 png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3930 png_const_bytep gamma_table = png_ptr->gamma_table;
3931 png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
3932 int gamma_shift = png_ptr->gamma_shift;
3936 png_uint_32 row_width=row_info->width;
3938 png_debug(1, "in png_do_gamma");
3940 if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
3941 (row_info->bit_depth == 16 && gamma_16_table != NULL)))
3943 switch (row_info->color_type)
3945 case PNG_COLOR_TYPE_RGB:
3947 if (row_info->bit_depth == 8)
3950 for (i = 0; i < row_width; i++)
3952 *sp = gamma_table[*sp];
3954 *sp = gamma_table[*sp];
3956 *sp = gamma_table[*sp];
3961 else /* if (row_info->bit_depth == 16) */
3964 for (i = 0; i < row_width; i++)
3968 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
3969 *sp = (png_byte)((v >> 8) & 0xff);
3970 *(sp + 1) = (png_byte)(v & 0xff);
3973 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
3974 *sp = (png_byte)((v >> 8) & 0xff);
3975 *(sp + 1) = (png_byte)(v & 0xff);
3978 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
3979 *sp = (png_byte)((v >> 8) & 0xff);
3980 *(sp + 1) = (png_byte)(v & 0xff);
3987 case PNG_COLOR_TYPE_RGB_ALPHA:
3989 if (row_info->bit_depth == 8)
3992 for (i = 0; i < row_width; i++)
3994 *sp = gamma_table[*sp];
3997 *sp = gamma_table[*sp];
4000 *sp = gamma_table[*sp];
4007 else /* if (row_info->bit_depth == 16) */
4010 for (i = 0; i < row_width; i++)
4012 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4013 *sp = (png_byte)((v >> 8) & 0xff);
4014 *(sp + 1) = (png_byte)(v & 0xff);
4017 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4018 *sp = (png_byte)((v >> 8) & 0xff);
4019 *(sp + 1) = (png_byte)(v & 0xff);
4022 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4023 *sp = (png_byte)((v >> 8) & 0xff);
4024 *(sp + 1) = (png_byte)(v & 0xff);
4031 case PNG_COLOR_TYPE_GRAY_ALPHA:
4033 if (row_info->bit_depth == 8)
4036 for (i = 0; i < row_width; i++)
4038 *sp = gamma_table[*sp];
4043 else /* if (row_info->bit_depth == 16) */
4046 for (i = 0; i < row_width; i++)
4048 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4049 *sp = (png_byte)((v >> 8) & 0xff);
4050 *(sp + 1) = (png_byte)(v & 0xff);
4057 case PNG_COLOR_TYPE_GRAY:
4059 if (row_info->bit_depth == 2)
4062 for (i = 0; i < row_width; i += 4)
4070 ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)|
4071 ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
4072 ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
4073 ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
4078 if (row_info->bit_depth == 4)
4081 for (i = 0; i < row_width; i += 2)
4083 int msb = *sp & 0xf0;
4084 int lsb = *sp & 0x0f;
4086 *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
4087 | (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
4092 else if (row_info->bit_depth == 8)
4095 for (i = 0; i < row_width; i++)
4097 *sp = gamma_table[*sp];
4102 else if (row_info->bit_depth == 16)
4105 for (i = 0; i < row_width; i++)
4107 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4108 *sp = (png_byte)((v >> 8) & 0xff);
4109 *(sp + 1) = (png_byte)(v & 0xff);
4123 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4124 /* Encode the alpha channel to the output gamma (the input channel is always
4125 * linear.) Called only with color types that have an alpha channel. Needs the
4129 png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
4131 png_uint_32 row_width = row_info->width;
4133 png_debug(1, "in png_do_encode_alpha");
4135 if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4137 if (row_info->bit_depth == 8)
4139 PNG_CONST png_bytep table = png_ptr->gamma_from_1;
4143 PNG_CONST int step =
4144 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
4146 /* The alpha channel is the last component: */
4149 for (; row_width > 0; --row_width, row += step)
4156 else if (row_info->bit_depth == 16)
4158 PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1;
4159 PNG_CONST int gamma_shift = png_ptr->gamma_shift;
4163 PNG_CONST int step =
4164 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
4166 /* The alpha channel is the last component: */
4169 for (; row_width > 0; --row_width, row += step)
4173 v = table[*(row + 1) >> gamma_shift][*row];
4174 *row = (png_byte)((v >> 8) & 0xff);
4175 *(row + 1) = (png_byte)(v & 0xff);
4183 /* Only get to here if called with a weird row_info; no harm has been done,
4184 * so just issue a warning.
4186 png_warning(png_ptr, "png_do_encode_alpha: unexpected call");
4190 #ifdef PNG_READ_EXPAND_SUPPORTED
4191 /* Expands a palette row to an RGB or RGBA row depending
4192 * upon whether you supply trans and num_trans.
4195 png_do_expand_palette(png_row_infop row_info, png_bytep row,
4196 png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
4201 png_uint_32 row_width=row_info->width;
4203 png_debug(1, "in png_do_expand_palette");
4205 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4207 if (row_info->bit_depth < 8)
4209 switch (row_info->bit_depth)
4213 sp = row + (png_size_t)((row_width - 1) >> 3);
4214 dp = row + (png_size_t)row_width - 1;
4215 shift = 7 - (int)((row_width + 7) & 0x07);
4216 for (i = 0; i < row_width; i++)
4218 if ((*sp >> shift) & 0x01)
4240 sp = row + (png_size_t)((row_width - 1) >> 2);
4241 dp = row + (png_size_t)row_width - 1;
4242 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4243 for (i = 0; i < row_width; i++)
4245 value = (*sp >> shift) & 0x03;
4246 *dp = (png_byte)value;
4263 sp = row + (png_size_t)((row_width - 1) >> 1);
4264 dp = row + (png_size_t)row_width - 1;
4265 shift = (int)((row_width & 0x01) << 2);
4266 for (i = 0; i < row_width; i++)
4268 value = (*sp >> shift) & 0x0f;
4269 *dp = (png_byte)value;
4287 row_info->bit_depth = 8;
4288 row_info->pixel_depth = 8;
4289 row_info->rowbytes = row_width;
4292 if (row_info->bit_depth == 8)
4297 sp = row + (png_size_t)row_width - 1;
4298 dp = row + (png_size_t)(row_width << 2) - 1;
4300 for (i = 0; i < row_width; i++)
4302 if ((int)(*sp) >= num_trans)
4306 *dp-- = trans_alpha[*sp];
4308 *dp-- = palette[*sp].blue;
4309 *dp-- = palette[*sp].green;
4310 *dp-- = palette[*sp].red;
4313 row_info->bit_depth = 8;
4314 row_info->pixel_depth = 32;
4315 row_info->rowbytes = row_width * 4;
4316 row_info->color_type = 6;
4317 row_info->channels = 4;
4322 sp = row + (png_size_t)row_width - 1;
4323 dp = row + (png_size_t)(row_width * 3) - 1;
4325 for (i = 0; i < row_width; i++)
4327 *dp-- = palette[*sp].blue;
4328 *dp-- = palette[*sp].green;
4329 *dp-- = palette[*sp].red;
4333 row_info->bit_depth = 8;
4334 row_info->pixel_depth = 24;
4335 row_info->rowbytes = row_width * 3;
4336 row_info->color_type = 2;
4337 row_info->channels = 3;
4344 /* If the bit depth < 8, it is expanded to 8. Also, if the already
4345 * expanded transparency value is supplied, an alpha channel is built.
4348 png_do_expand(png_row_infop row_info, png_bytep row,
4349 png_const_color_16p trans_color)
4354 png_uint_32 row_width=row_info->width;
4356 png_debug(1, "in png_do_expand");
4359 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
4361 unsigned int gray = trans_color != NULL ? trans_color->gray : 0;
4363 if (row_info->bit_depth < 8)
4365 switch (row_info->bit_depth)
4369 gray = (gray & 0x01) * 0xff;
4370 sp = row + (png_size_t)((row_width - 1) >> 3);
4371 dp = row + (png_size_t)row_width - 1;
4372 shift = 7 - (int)((row_width + 7) & 0x07);
4373 for (i = 0; i < row_width; i++)
4375 if ((*sp >> shift) & 0x01)
4397 gray = (gray & 0x03) * 0x55;
4398 sp = row + (png_size_t)((row_width - 1) >> 2);
4399 dp = row + (png_size_t)row_width - 1;
4400 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4401 for (i = 0; i < row_width; i++)
4403 value = (*sp >> shift) & 0x03;
4404 *dp = (png_byte)(value | (value << 2) | (value << 4) |
4422 gray = (gray & 0x0f) * 0x11;
4423 sp = row + (png_size_t)((row_width - 1) >> 1);
4424 dp = row + (png_size_t)row_width - 1;
4425 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
4426 for (i = 0; i < row_width; i++)
4428 value = (*sp >> shift) & 0x0f;
4429 *dp = (png_byte)(value | (value << 4));
4448 row_info->bit_depth = 8;
4449 row_info->pixel_depth = 8;
4450 row_info->rowbytes = row_width;
4453 if (trans_color != NULL)
4455 if (row_info->bit_depth == 8)
4458 sp = row + (png_size_t)row_width - 1;
4459 dp = row + (png_size_t)(row_width << 1) - 1;
4461 for (i = 0; i < row_width; i++)
4473 else if (row_info->bit_depth == 16)
4475 unsigned int gray_high = (gray >> 8) & 0xff;
4476 unsigned int gray_low = gray & 0xff;
4477 sp = row + row_info->rowbytes - 1;
4478 dp = row + (row_info->rowbytes << 1) - 1;
4479 for (i = 0; i < row_width; i++)
4481 if (*(sp - 1) == gray_high && *(sp) == gray_low)
4498 row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
4499 row_info->channels = 2;
4500 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
4501 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
4505 else if (row_info->color_type == PNG_COLOR_TYPE_RGB &&
4506 trans_color != NULL)
4508 if (row_info->bit_depth == 8)
4510 png_byte red = (png_byte)(trans_color->red & 0xff);
4511 png_byte green = (png_byte)(trans_color->green & 0xff);
4512 png_byte blue = (png_byte)(trans_color->blue & 0xff);
4513 sp = row + (png_size_t)row_info->rowbytes - 1;
4514 dp = row + (png_size_t)(row_width << 2) - 1;
4515 for (i = 0; i < row_width; i++)
4517 if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
4528 else if (row_info->bit_depth == 16)
4530 png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff);
4531 png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff);
4532 png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff);
4533 png_byte red_low = (png_byte)(trans_color->red & 0xff);
4534 png_byte green_low = (png_byte)(trans_color->green & 0xff);
4535 png_byte blue_low = (png_byte)(trans_color->blue & 0xff);
4536 sp = row + row_info->rowbytes - 1;
4537 dp = row + (png_size_t)(row_width << 3) - 1;
4538 for (i = 0; i < row_width; i++)
4540 if (*(sp - 5) == red_high &&
4541 *(sp - 4) == red_low &&
4542 *(sp - 3) == green_high &&
4543 *(sp - 2) == green_low &&
4544 *(sp - 1) == blue_high &&
4565 row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
4566 row_info->channels = 4;
4567 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
4568 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4574 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4575 /* If the bit depth is 8 and the color type is not a palette type expand the
4576 * whole row to 16 bits. Has no effect otherwise.
4579 png_do_expand_16(png_row_infop row_info, png_bytep row)
4581 if (row_info->bit_depth == 8 &&
4582 row_info->color_type != PNG_COLOR_TYPE_PALETTE)
4584 /* The row have a sequence of bytes containing [0..255] and we need
4585 * to turn it into another row containing [0..65535], to do this we
4588 * (input / 255) * 65535
4590 * Which happens to be exactly input * 257 and this can be achieved
4591 * simply by byte replication in place (copying backwards).
4593 png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */
4594 png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */
4596 dp[-2] = dp[-1] = *--sp, dp -= 2;
4598 row_info->rowbytes *= 2;
4599 row_info->bit_depth = 16;
4600 row_info->pixel_depth = (png_byte)(row_info->channels * 16);
4605 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4607 png_do_quantize(png_row_infop row_info, png_bytep row,
4608 png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
4612 png_uint_32 row_width=row_info->width;
4614 png_debug(1, "in png_do_quantize");
4616 if (row_info->bit_depth == 8)
4618 if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup)
4623 for (i = 0; i < row_width; i++)
4629 /* This looks real messy, but the compiler will reduce
4630 * it down to a reasonable formula. For example, with
4631 * 5 bits per color, we get:
4632 * p = (((r >> 3) & 0x1f) << 10) |
4633 * (((g >> 3) & 0x1f) << 5) |
4634 * ((b >> 3) & 0x1f);
4636 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4637 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4638 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4639 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4640 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4641 (PNG_QUANTIZE_BLUE_BITS)) |
4642 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4643 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4645 *dp++ = palette_lookup[p];
4648 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4649 row_info->channels = 1;
4650 row_info->pixel_depth = row_info->bit_depth;
4651 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4654 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
4655 palette_lookup != NULL)
4660 for (i = 0; i < row_width; i++)
4667 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4668 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4669 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4670 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4671 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4672 (PNG_QUANTIZE_BLUE_BITS)) |
4673 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4674 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4676 *dp++ = palette_lookup[p];
4679 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4680 row_info->channels = 1;
4681 row_info->pixel_depth = row_info->bit_depth;
4682 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4685 else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4690 for (i = 0; i < row_width; i++, sp++)
4692 *sp = quantize_lookup[*sp];
4697 #endif /* READ_QUANTIZE */
4699 /* Transform the row. The order of transformations is significant,
4700 * and is very touchy. If you add a transformation, take care to
4701 * decide how it fits in with the other transformations here.
4704 png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
4706 png_debug(1, "in png_do_read_transformations");
4708 if (png_ptr->row_buf == NULL)
4710 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
4711 * error is incredibly rare and incredibly easy to debug without this
4714 png_error(png_ptr, "NULL row buffer");
4717 /* The following is debugging; prior to 1.5.4 the code was never compiled in;
4718 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
4719 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for
4720 * all transformations, however in practice the ROW_INIT always gets done on
4721 * demand, if necessary.
4723 if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
4724 (png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
4726 /* Application has failed to call either png_read_start_image() or
4727 * png_read_update_info() after setting transforms that expand pixels.
4728 * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
4730 png_error(png_ptr, "Uninitialized row");
4733 #ifdef PNG_READ_EXPAND_SUPPORTED
4734 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4736 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4738 png_do_expand_palette(row_info, png_ptr->row_buf + 1,
4739 png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
4744 if (png_ptr->num_trans != 0 &&
4745 (png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
4746 png_do_expand(row_info, png_ptr->row_buf + 1,
4747 &(png_ptr->trans_color));
4750 png_do_expand(row_info, png_ptr->row_buf + 1,
4756 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4757 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4758 (png_ptr->transformations & PNG_COMPOSE) == 0 &&
4759 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4760 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4761 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4762 0 /* at_start == false, because SWAP_ALPHA happens later */);
4765 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4766 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
4769 png_do_rgb_to_gray(png_ptr, row_info,
4770 png_ptr->row_buf + 1);
4774 png_ptr->rgb_to_gray_status=1;
4775 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4776 PNG_RGB_TO_GRAY_WARN)
4777 png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4779 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4780 PNG_RGB_TO_GRAY_ERR)
4781 png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4786 /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
4788 * In most cases, the "simple transparency" should be done prior to doing
4789 * gray-to-RGB, or you will have to test 3x as many bytes to check if a
4790 * pixel is transparent. You would also need to make sure that the
4791 * transparency information is upgraded to RGB.
4793 * To summarize, the current flow is:
4794 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
4795 * with background "in place" if transparent,
4796 * convert to RGB if necessary
4797 * - Gray + alpha -> composite with gray background and remove alpha bytes,
4798 * convert to RGB if necessary
4800 * To support RGB backgrounds for gray images we need:
4801 * - Gray + simple transparency -> convert to RGB + simple transparency,
4802 * compare 3 or 6 bytes and composite with
4803 * background "in place" if transparent
4804 * (3x compare/pixel compared to doing
4805 * composite with gray bkgrnd)
4806 * - Gray + alpha -> convert to RGB + alpha, composite with background and
4807 * remove alpha bytes (3x float
4808 * operations/pixel compared with composite
4809 * on gray background)
4811 * Greg's change will do this. The reason it wasn't done before is for
4812 * performance, as this increases the per-pixel operations. If we would check
4813 * in advance if the background was gray or RGB, and position the gray-to-RGB
4814 * transform appropriately, then it would save a lot of work/time.
4817 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4818 /* If gray -> RGB, do so now only if background is non-gray; else do later
4819 * for performance reasons
4821 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4822 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) == 0)
4823 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4826 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4827 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4828 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
4829 png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
4832 #ifdef PNG_READ_GAMMA_SUPPORTED
4833 if ((png_ptr->transformations & PNG_GAMMA) != 0 &&
4834 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4835 /* Because RGB_TO_GRAY does the gamma transform. */
4836 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0 &&
4838 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4839 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4840 /* Because PNG_COMPOSE does the gamma transform if there is something to
4841 * do (if there is an alpha channel or transparency.)
4843 !((png_ptr->transformations & PNG_COMPOSE) != 0 &&
4844 ((png_ptr->num_trans != 0) ||
4845 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)) &&
4847 /* Because png_init_read_transformations transforms the palette, unless
4848 * RGB_TO_GRAY will do the transform.
4850 (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
4851 png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
4854 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4855 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4856 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
4857 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4858 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4859 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4860 0 /* at_start == false, because SWAP_ALPHA happens later */);
4863 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4864 if ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
4865 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4866 png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
4869 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
4870 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
4871 png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
4874 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
4875 /* There is no harm in doing both of these because only one has any effect,
4876 * by putting the 'scale' option first if the app asks for scale (either by
4877 * calling the API or in a TRANSFORM flag) this is what happens.
4879 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
4880 png_do_chop(row_info, png_ptr->row_buf + 1);
4883 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4884 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
4886 png_do_quantize(row_info, png_ptr->row_buf + 1,
4887 png_ptr->palette_lookup, png_ptr->quantize_index);
4889 if (row_info->rowbytes == 0)
4890 png_error(png_ptr, "png_do_quantize returned rowbytes=0");
4892 #endif /* READ_QUANTIZE */
4894 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4895 /* Do the expansion now, after all the arithmetic has been done. Notice
4896 * that previous transformations can handle the PNG_EXPAND_16 flag if this
4897 * is efficient (particularly true in the case of gamma correction, where
4898 * better accuracy results faster!)
4900 if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
4901 png_do_expand_16(row_info, png_ptr->row_buf + 1);
4904 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4905 /* NOTE: moved here in 1.5.4 (from much later in this list.) */
4906 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4907 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) != 0)
4908 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4911 #ifdef PNG_READ_INVERT_SUPPORTED
4912 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
4913 png_do_invert(row_info, png_ptr->row_buf + 1);
4916 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
4917 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
4918 png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
4921 #ifdef PNG_READ_SHIFT_SUPPORTED
4922 if ((png_ptr->transformations & PNG_SHIFT) != 0)
4923 png_do_unshift(row_info, png_ptr->row_buf + 1,
4927 #ifdef PNG_READ_PACK_SUPPORTED
4928 if ((png_ptr->transformations & PNG_PACK) != 0)
4929 png_do_unpack(row_info, png_ptr->row_buf + 1);
4932 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
4933 /* Added at libpng-1.5.10 */
4934 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4935 png_ptr->num_palette_max >= 0)
4936 png_do_check_palette_indexes(png_ptr, row_info);
4939 #ifdef PNG_READ_BGR_SUPPORTED
4940 if ((png_ptr->transformations & PNG_BGR) != 0)
4941 png_do_bgr(row_info, png_ptr->row_buf + 1);
4944 #ifdef PNG_READ_PACKSWAP_SUPPORTED
4945 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
4946 png_do_packswap(row_info, png_ptr->row_buf + 1);
4949 #ifdef PNG_READ_FILLER_SUPPORTED
4950 if ((png_ptr->transformations & PNG_FILLER) != 0)
4951 png_do_read_filler(row_info, png_ptr->row_buf + 1,
4952 (png_uint_32)png_ptr->filler, png_ptr->flags);
4955 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
4956 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
4957 png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
4960 #ifdef PNG_READ_16BIT_SUPPORTED
4961 #ifdef PNG_READ_SWAP_SUPPORTED
4962 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
4963 png_do_swap(row_info, png_ptr->row_buf + 1);
4967 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
4968 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
4970 if (png_ptr->read_user_transform_fn != NULL)
4971 (*(png_ptr->read_user_transform_fn)) /* User read transform function */
4972 (png_ptr, /* png_ptr */
4973 row_info, /* row_info: */
4974 /* png_uint_32 width; width of row */
4975 /* png_size_t rowbytes; number of bytes in row */
4976 /* png_byte color_type; color type of pixels */
4977 /* png_byte bit_depth; bit depth of samples */
4978 /* png_byte channels; number of channels (1-4) */
4979 /* png_byte pixel_depth; bits per pixel (depth*channels) */
4980 png_ptr->row_buf + 1); /* start of pixel data for row */
4981 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
4982 if (png_ptr->user_transform_depth != 0)
4983 row_info->bit_depth = png_ptr->user_transform_depth;
4985 if (png_ptr->user_transform_channels != 0)
4986 row_info->channels = png_ptr->user_transform_channels;
4988 row_info->pixel_depth = (png_byte)(row_info->bit_depth *
4989 row_info->channels);
4991 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
4996 #endif /* READ_TRANSFORMS */