2 /* pngrtran.c - transforms the data in a row for PNG readers
4 * Last changed in libpng 1.5.10 [March 8, 2012]
5 * Copyright (c) 1998-2012 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_structp 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_BACKGROUND_SUPPORTED
92 /* Handle alpha and tRNS via a background color */
94 png_set_background_fixed(png_structp png_ptr
,
95 png_const_color_16p background_color
, int background_gamma_code
,
96 int need_expand
, png_fixed_point background_gamma
)
98 png_debug(1, "in png_set_background_fixed");
103 if (background_gamma_code
== PNG_BACKGROUND_GAMMA_UNKNOWN
)
105 png_warning(png_ptr
, "Application must supply a known background gamma");
109 png_ptr
->transformations
|= PNG_COMPOSE
| PNG_STRIP_ALPHA
;
110 png_ptr
->transformations
&= ~PNG_ENCODE_ALPHA
;
111 png_ptr
->flags
&= ~PNG_FLAG_OPTIMIZE_ALPHA
;
113 png_memcpy(&(png_ptr
->background
), background_color
,
114 png_sizeof(png_color_16
));
115 png_ptr
->background_gamma
= background_gamma
;
116 png_ptr
->background_gamma_type
= (png_byte
)(background_gamma_code
);
118 png_ptr
->transformations
|= PNG_BACKGROUND_EXPAND
;
120 png_ptr
->transformations
&= ~PNG_BACKGROUND_EXPAND
;
123 # ifdef PNG_FLOATING_POINT_SUPPORTED
125 png_set_background(png_structp png_ptr
,
126 png_const_color_16p background_color
, int background_gamma_code
,
127 int need_expand
, double background_gamma
)
129 png_set_background_fixed(png_ptr
, background_color
, background_gamma_code
,
130 need_expand
, png_fixed(png_ptr
, background_gamma
, "png_set_background"));
132 # endif /* FLOATING_POINT */
133 #endif /* READ_BACKGROUND */
135 /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
136 * one that pngrtran does first (scale) happens. This is necessary to allow the
137 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
139 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
141 png_set_scale_16(png_structp png_ptr
)
143 png_debug(1, "in png_set_scale_16");
148 png_ptr
->transformations
|= PNG_SCALE_16_TO_8
;
152 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
153 /* Chop 16-bit depth files to 8-bit depth */
155 png_set_strip_16(png_structp png_ptr
)
157 png_debug(1, "in png_set_strip_16");
162 png_ptr
->transformations
|= PNG_16_TO_8
;
166 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
168 png_set_strip_alpha(png_structp png_ptr
)
170 png_debug(1, "in png_set_strip_alpha");
175 png_ptr
->transformations
|= PNG_STRIP_ALPHA
;
179 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
180 static png_fixed_point
181 translate_gamma_flags(png_structp png_ptr
, png_fixed_point output_gamma
,
184 /* Check for flag values. The main reason for having the old Mac value as a
185 * flag is that it is pretty near impossible to work out what the correct
186 * value is from Apple documentation - a working Mac system is needed to
187 * discover the value!
189 if (output_gamma
== PNG_DEFAULT_sRGB
||
190 output_gamma
== PNG_FP_1
/ PNG_DEFAULT_sRGB
)
192 /* If there is no sRGB support this just sets the gamma to the standard
193 * sRGB value. (This is a side effect of using this function!)
195 # ifdef PNG_READ_sRGB_SUPPORTED
196 png_ptr
->flags
|= PNG_FLAG_ASSUME_sRGB
;
199 output_gamma
= PNG_GAMMA_sRGB
;
201 output_gamma
= PNG_GAMMA_sRGB_INVERSE
;
204 else if (output_gamma
== PNG_GAMMA_MAC_18
||
205 output_gamma
== PNG_FP_1
/ PNG_GAMMA_MAC_18
)
208 output_gamma
= PNG_GAMMA_MAC_OLD
;
210 output_gamma
= PNG_GAMMA_MAC_INVERSE
;
216 # ifdef PNG_FLOATING_POINT_SUPPORTED
217 static png_fixed_point
218 convert_gamma_value(png_structp png_ptr
, double output_gamma
)
220 /* The following silently ignores cases where fixed point (times 100,000)
221 * gamma values are passed to the floating point API. This is safe and it
222 * means the fixed point constants work just fine with the floating point
223 * API. The alternative would just lead to undetected errors and spurious
224 * bug reports. Negative values fail inside the _fixed API unless they
225 * correspond to the flag values.
227 if (output_gamma
> 0 && output_gamma
< 128)
228 output_gamma
*= PNG_FP_1
;
230 /* This preserves -1 and -2 exactly: */
231 output_gamma
= floor(output_gamma
+ .5);
233 if (output_gamma
> PNG_FP_MAX
|| output_gamma
< PNG_FP_MIN
)
234 png_fixed_error(png_ptr
, "gamma value");
236 return (png_fixed_point
)output_gamma
;
239 #endif /* READ_ALPHA_MODE || READ_GAMMA */
241 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
243 png_set_alpha_mode_fixed(png_structp png_ptr
, int mode
,
244 png_fixed_point output_gamma
)
247 png_fixed_point file_gamma
;
249 png_debug(1, "in png_set_alpha_mode");
254 output_gamma
= translate_gamma_flags(png_ptr
, output_gamma
, 1/*screen*/);
256 /* Validate the value to ensure it is in a reasonable range. The value
257 * is expected to be 1 or greater, but this range test allows for some
258 * viewing correction values. The intent is to weed out users of this API
259 * who use the inverse of the gamma value accidentally! Since some of these
260 * values are reasonable this may have to be changed.
262 if (output_gamma
< 70000 || output_gamma
> 300000)
263 png_error(png_ptr
, "output gamma out of expected range");
265 /* The default file gamma is the inverse of the output gamma; the output
266 * gamma may be changed below so get the file value first:
268 file_gamma
= png_reciprocal(output_gamma
);
270 /* There are really 8 possibilities here, composed of any combination
273 * premultiply the color channels
274 * do not encode non-opaque pixels
275 * encode the alpha as well as the color channels
277 * The differences disappear if the input/output ('screen') gamma is 1.0,
278 * because then the encoding is a no-op and there is only the choice of
279 * premultiplying the color channels or not.
281 * png_set_alpha_mode and png_set_background interact because both use
282 * png_compose to do the work. Calling both is only useful when
283 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
284 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
288 case PNG_ALPHA_PNG
: /* default: png standard */
289 /* No compose, but it may be set by png_set_background! */
290 png_ptr
->transformations
&= ~PNG_ENCODE_ALPHA
;
291 png_ptr
->flags
&= ~PNG_FLAG_OPTIMIZE_ALPHA
;
294 case PNG_ALPHA_ASSOCIATED
: /* color channels premultiplied */
296 png_ptr
->transformations
&= ~PNG_ENCODE_ALPHA
;
297 png_ptr
->flags
&= ~PNG_FLAG_OPTIMIZE_ALPHA
;
298 /* The output is linear: */
299 output_gamma
= PNG_FP_1
;
302 case PNG_ALPHA_OPTIMIZED
: /* associated, non-opaque pixels linear */
304 png_ptr
->transformations
&= ~PNG_ENCODE_ALPHA
;
305 png_ptr
->flags
|= PNG_FLAG_OPTIMIZE_ALPHA
;
306 /* output_gamma records the encoding of opaque pixels! */
309 case PNG_ALPHA_BROKEN
: /* associated, non-linear, alpha encoded */
311 png_ptr
->transformations
|= PNG_ENCODE_ALPHA
;
312 png_ptr
->flags
&= ~PNG_FLAG_OPTIMIZE_ALPHA
;
316 png_error(png_ptr
, "invalid alpha mode");
319 /* Only set the default gamma if the file gamma has not been set (this has
320 * the side effect that the gamma in a second call to png_set_alpha_mode will
323 if (png_ptr
->gamma
== 0)
324 png_ptr
->gamma
= file_gamma
;
326 /* But always set the output gamma: */
327 png_ptr
->screen_gamma
= output_gamma
;
329 /* Finally, if pre-multiplying, set the background fields to achieve the
334 /* And obtain alpha pre-multiplication by composing on black: */
335 png_memset(&png_ptr
->background
, 0, sizeof png_ptr
->background
);
336 png_ptr
->background_gamma
= png_ptr
->gamma
; /* just in case */
337 png_ptr
->background_gamma_type
= PNG_BACKGROUND_GAMMA_FILE
;
338 png_ptr
->transformations
&= ~PNG_BACKGROUND_EXPAND
;
340 if (png_ptr
->transformations
& PNG_COMPOSE
)
342 "conflicting calls to set alpha mode and background");
344 png_ptr
->transformations
|= PNG_COMPOSE
;
347 /* New API, make sure apps call the correct initializers: */
348 png_ptr
->flags
|= PNG_FLAG_DETECT_UNINITIALIZED
;
351 # ifdef PNG_FLOATING_POINT_SUPPORTED
353 png_set_alpha_mode(png_structp png_ptr
, int mode
, double output_gamma
)
355 png_set_alpha_mode_fixed(png_ptr
, mode
, convert_gamma_value(png_ptr
,
361 #ifdef PNG_READ_QUANTIZE_SUPPORTED
362 /* Dither file to 8-bit. Supply a palette, the current number
363 * of elements in the palette, the maximum number of elements
364 * allowed, and a histogram if possible. If the current number
365 * of colors is greater then the maximum number, the palette will be
366 * modified to fit in the maximum number. "full_quantize" indicates
367 * whether we need a quantizing cube set up for RGB images, or if we
368 * simply are reducing the number of colors in a paletted image.
371 typedef struct png_dsort_struct
373 struct png_dsort_struct FAR
* next
;
377 typedef png_dsort FAR
* png_dsortp
;
378 typedef png_dsort FAR
* FAR
* png_dsortpp
;
381 png_set_quantize(png_structp png_ptr
, png_colorp palette
,
382 int num_palette
, int maximum_colors
, png_const_uint_16p histogram
,
385 png_debug(1, "in png_set_quantize");
390 png_ptr
->transformations
|= PNG_QUANTIZE
;
396 png_ptr
->quantize_index
= (png_bytep
)png_malloc(png_ptr
,
397 (png_uint_32
)(num_palette
* png_sizeof(png_byte
)));
398 for (i
= 0; i
< num_palette
; i
++)
399 png_ptr
->quantize_index
[i
] = (png_byte
)i
;
402 if (num_palette
> maximum_colors
)
404 if (histogram
!= NULL
)
406 /* This is easy enough, just throw out the least used colors.
407 * Perhaps not the best solution, but good enough.
412 /* Initialize an array to sort colors */
413 png_ptr
->quantize_sort
= (png_bytep
)png_malloc(png_ptr
,
414 (png_uint_32
)(num_palette
* png_sizeof(png_byte
)));
416 /* Initialize the quantize_sort array */
417 for (i
= 0; i
< num_palette
; i
++)
418 png_ptr
->quantize_sort
[i
] = (png_byte
)i
;
420 /* Find the least used palette entries by starting a
421 * bubble sort, and running it until we have sorted
422 * out enough colors. Note that we don't care about
423 * sorting all the colors, just finding which are
427 for (i
= num_palette
- 1; i
>= maximum_colors
; i
--)
429 int done
; /* To stop early if the list is pre-sorted */
433 for (j
= 0; j
< i
; j
++)
435 if (histogram
[png_ptr
->quantize_sort
[j
]]
436 < histogram
[png_ptr
->quantize_sort
[j
+ 1]])
440 t
= png_ptr
->quantize_sort
[j
];
441 png_ptr
->quantize_sort
[j
] = png_ptr
->quantize_sort
[j
+ 1];
442 png_ptr
->quantize_sort
[j
+ 1] = t
;
451 /* Swap the palette around, and set up a table, if necessary */
456 /* Put all the useful colors within the max, but don't
459 for (i
= 0; i
< maximum_colors
; i
++)
461 if ((int)png_ptr
->quantize_sort
[i
] >= maximum_colors
)
465 while ((int)png_ptr
->quantize_sort
[j
] >= maximum_colors
);
467 palette
[i
] = palette
[j
];
475 /* Move all the used colors inside the max limit, and
476 * develop a translation table.
478 for (i
= 0; i
< maximum_colors
; i
++)
480 /* Only move the colors we need to */
481 if ((int)png_ptr
->quantize_sort
[i
] >= maximum_colors
)
487 while ((int)png_ptr
->quantize_sort
[j
] >= maximum_colors
);
489 tmp_color
= palette
[j
];
490 palette
[j
] = palette
[i
];
491 palette
[i
] = tmp_color
;
492 /* Indicate where the color went */
493 png_ptr
->quantize_index
[j
] = (png_byte
)i
;
494 png_ptr
->quantize_index
[i
] = (png_byte
)j
;
498 /* Find closest color for those colors we are not using */
499 for (i
= 0; i
< num_palette
; i
++)
501 if ((int)png_ptr
->quantize_index
[i
] >= maximum_colors
)
503 int min_d
, k
, min_k
, d_index
;
505 /* Find the closest color to one we threw out */
506 d_index
= png_ptr
->quantize_index
[i
];
507 min_d
= PNG_COLOR_DIST(palette
[d_index
], palette
[0]);
508 for (k
= 1, min_k
= 0; k
< maximum_colors
; k
++)
512 d
= PNG_COLOR_DIST(palette
[d_index
], palette
[k
]);
520 /* Point to closest color */
521 png_ptr
->quantize_index
[i
] = (png_byte
)min_k
;
525 png_free(png_ptr
, png_ptr
->quantize_sort
);
526 png_ptr
->quantize_sort
= NULL
;
530 /* This is much harder to do simply (and quickly). Perhaps
531 * we need to go through a median cut routine, but those
532 * don't always behave themselves with only a few colors
533 * as input. So we will just find the closest two colors,
534 * and throw out one of them (chosen somewhat randomly).
535 * [We don't understand this at all, so if someone wants to
536 * work on improving it, be our guest - AED, GRP]
546 /* Initialize palette index arrays */
547 png_ptr
->index_to_palette
= (png_bytep
)png_malloc(png_ptr
,
548 (png_uint_32
)(num_palette
* png_sizeof(png_byte
)));
549 png_ptr
->palette_to_index
= (png_bytep
)png_malloc(png_ptr
,
550 (png_uint_32
)(num_palette
* png_sizeof(png_byte
)));
552 /* Initialize the sort array */
553 for (i
= 0; i
< num_palette
; i
++)
555 png_ptr
->index_to_palette
[i
] = (png_byte
)i
;
556 png_ptr
->palette_to_index
[i
] = (png_byte
)i
;
559 hash
= (png_dsortpp
)png_calloc(png_ptr
, (png_uint_32
)(769 *
560 png_sizeof(png_dsortp
)));
562 num_new_palette
= num_palette
;
564 /* Initial wild guess at how far apart the farthest pixel
565 * pair we will be eliminating will be. Larger
566 * numbers mean more areas will be allocated, Smaller
567 * numbers run the risk of not saving enough data, and
568 * having to do this all over again.
570 * I have not done extensive checking on this number.
574 while (num_new_palette
> maximum_colors
)
576 for (i
= 0; i
< num_new_palette
- 1; i
++)
580 for (j
= i
+ 1; j
< num_new_palette
; j
++)
584 d
= PNG_COLOR_DIST(palette
[i
], palette
[j
]);
589 t
= (png_dsortp
)png_malloc_warn(png_ptr
,
590 (png_uint_32
)(png_sizeof(png_dsort
)));
596 t
->left
= (png_byte
)i
;
597 t
->right
= (png_byte
)j
;
606 for (i
= 0; i
<= max_d
; i
++)
612 for (p
= hash
[i
]; p
; p
= p
->next
)
614 if ((int)png_ptr
->index_to_palette
[p
->left
]
616 (int)png_ptr
->index_to_palette
[p
->right
]
621 if (num_new_palette
& 0x01)
633 palette
[png_ptr
->index_to_palette
[j
]]
634 = palette
[num_new_palette
];
639 for (k
= 0; k
< num_palette
; k
++)
641 if (png_ptr
->quantize_index
[k
] ==
642 png_ptr
->index_to_palette
[j
])
643 png_ptr
->quantize_index
[k
] =
644 png_ptr
->index_to_palette
[next_j
];
646 if ((int)png_ptr
->quantize_index
[k
] ==
648 png_ptr
->quantize_index
[k
] =
649 png_ptr
->index_to_palette
[j
];
653 png_ptr
->index_to_palette
[png_ptr
->palette_to_index
654 [num_new_palette
]] = png_ptr
->index_to_palette
[j
];
656 png_ptr
->palette_to_index
[png_ptr
->index_to_palette
[j
]]
657 = png_ptr
->palette_to_index
[num_new_palette
];
659 png_ptr
->index_to_palette
[j
] =
660 (png_byte
)num_new_palette
;
662 png_ptr
->palette_to_index
[num_new_palette
] =
665 if (num_new_palette
<= maximum_colors
)
668 if (num_new_palette
<= maximum_colors
)
673 for (i
= 0; i
< 769; i
++)
677 png_dsortp p
= hash
[i
];
681 png_free(png_ptr
, p
);
689 png_free(png_ptr
, hash
);
690 png_free(png_ptr
, png_ptr
->palette_to_index
);
691 png_free(png_ptr
, png_ptr
->index_to_palette
);
692 png_ptr
->palette_to_index
= NULL
;
693 png_ptr
->index_to_palette
= NULL
;
695 num_palette
= maximum_colors
;
697 if (png_ptr
->palette
== NULL
)
699 png_ptr
->palette
= palette
;
701 png_ptr
->num_palette
= (png_uint_16
)num_palette
;
707 int total_bits
= PNG_QUANTIZE_RED_BITS
+ PNG_QUANTIZE_GREEN_BITS
+
708 PNG_QUANTIZE_BLUE_BITS
;
709 int num_red
= (1 << PNG_QUANTIZE_RED_BITS
);
710 int num_green
= (1 << PNG_QUANTIZE_GREEN_BITS
);
711 int num_blue
= (1 << PNG_QUANTIZE_BLUE_BITS
);
712 png_size_t num_entries
= ((png_size_t
)1 << total_bits
);
714 png_ptr
->palette_lookup
= (png_bytep
)png_calloc(png_ptr
,
715 (png_uint_32
)(num_entries
* png_sizeof(png_byte
)));
717 distance
= (png_bytep
)png_malloc(png_ptr
, (png_uint_32
)(num_entries
*
718 png_sizeof(png_byte
)));
720 png_memset(distance
, 0xff, num_entries
* png_sizeof(png_byte
));
722 for (i
= 0; i
< num_palette
; i
++)
725 int r
= (palette
[i
].red
>> (8 - PNG_QUANTIZE_RED_BITS
));
726 int g
= (palette
[i
].green
>> (8 - PNG_QUANTIZE_GREEN_BITS
));
727 int b
= (palette
[i
].blue
>> (8 - PNG_QUANTIZE_BLUE_BITS
));
729 for (ir
= 0; ir
< num_red
; ir
++)
731 /* int dr = abs(ir - r); */
732 int dr
= ((ir
> r
) ? ir
- r
: r
- ir
);
733 int index_r
= (ir
<< (PNG_QUANTIZE_BLUE_BITS
+
734 PNG_QUANTIZE_GREEN_BITS
));
736 for (ig
= 0; ig
< num_green
; ig
++)
738 /* int dg = abs(ig - g); */
739 int dg
= ((ig
> g
) ? ig
- g
: g
- ig
);
741 int dm
= ((dr
> dg
) ? dr
: dg
);
742 int index_g
= index_r
| (ig
<< PNG_QUANTIZE_BLUE_BITS
);
744 for (ib
= 0; ib
< num_blue
; ib
++)
746 int d_index
= index_g
| ib
;
747 /* int db = abs(ib - b); */
748 int db
= ((ib
> b
) ? ib
- b
: b
- ib
);
749 int dmax
= ((dm
> db
) ? dm
: db
);
750 int d
= dmax
+ dt
+ db
;
752 if (d
< (int)distance
[d_index
])
754 distance
[d_index
] = (png_byte
)d
;
755 png_ptr
->palette_lookup
[d_index
] = (png_byte
)i
;
762 png_free(png_ptr
, distance
);
765 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
767 #ifdef PNG_READ_GAMMA_SUPPORTED
769 png_set_gamma_fixed(png_structp png_ptr
, png_fixed_point scrn_gamma
,
770 png_fixed_point file_gamma
)
772 png_debug(1, "in png_set_gamma_fixed");
777 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
778 scrn_gamma
= translate_gamma_flags(png_ptr
, scrn_gamma
, 1/*screen*/);
779 file_gamma
= translate_gamma_flags(png_ptr
, file_gamma
, 0/*file*/);
781 #if PNG_LIBPNG_VER >= 10600
782 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
783 * premultiplied alpha support; this actually hides an undocumented feature
784 * of the previous implementation which allowed gamma processing to be
785 * disabled in background handling. There is no evidence (so far) that this
786 * was being used; however, png_set_background itself accepted and must still
787 * accept '0' for the gamma value it takes, because it isn't always used.
789 * Since this is an API change (albeit a very minor one that removes an
790 * undocumented API feature) it will not be made until libpng-1.6.0.
793 png_error(png_ptr
, "invalid file gamma in png_set_gamma");
796 png_error(png_ptr
, "invalid screen gamma in png_set_gamma");
799 /* Set the gamma values unconditionally - this overrides the value in the PNG
800 * file if a gAMA chunk was present. png_set_alpha_mode provides a
801 * different, easier, way to default the file gamma.
803 png_ptr
->gamma
= file_gamma
;
804 png_ptr
->screen_gamma
= scrn_gamma
;
807 # ifdef PNG_FLOATING_POINT_SUPPORTED
809 png_set_gamma(png_structp png_ptr
, double scrn_gamma
, double file_gamma
)
811 png_set_gamma_fixed(png_ptr
, convert_gamma_value(png_ptr
, scrn_gamma
),
812 convert_gamma_value(png_ptr
, file_gamma
));
814 # endif /* FLOATING_POINT_SUPPORTED */
815 #endif /* READ_GAMMA */
817 #ifdef PNG_READ_EXPAND_SUPPORTED
818 /* Expand paletted images to RGB, expand grayscale images of
819 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
823 png_set_expand(png_structp png_ptr
)
825 png_debug(1, "in png_set_expand");
830 png_ptr
->transformations
|= (PNG_EXPAND
| PNG_EXPAND_tRNS
);
831 png_ptr
->flags
&= ~PNG_FLAG_ROW_INIT
;
834 /* GRR 19990627: the following three functions currently are identical
835 * to png_set_expand(). However, it is entirely reasonable that someone
836 * might wish to expand an indexed image to RGB but *not* expand a single,
837 * fully transparent palette entry to a full alpha channel--perhaps instead
838 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
839 * the transparent color with a particular RGB value, or drop tRNS entirely.
840 * IOW, a future version of the library may make the transformations flag
841 * a bit more fine-grained, with separate bits for each of these three
844 * More to the point, these functions make it obvious what libpng will be
845 * doing, whereas "expand" can (and does) mean any number of things.
847 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
848 * to expand only the sample depth but not to expand the tRNS to alpha
849 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
852 /* Expand paletted images to RGB. */
854 png_set_palette_to_rgb(png_structp png_ptr
)
856 png_debug(1, "in png_set_palette_to_rgb");
861 png_ptr
->transformations
|= (PNG_EXPAND
| PNG_EXPAND_tRNS
);
862 png_ptr
->flags
&= ~PNG_FLAG_ROW_INIT
;
865 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
867 png_set_expand_gray_1_2_4_to_8(png_structp png_ptr
)
869 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
874 png_ptr
->transformations
|= PNG_EXPAND
;
875 png_ptr
->flags
&= ~PNG_FLAG_ROW_INIT
;
880 /* Expand tRNS chunks to alpha channels. */
882 png_set_tRNS_to_alpha(png_structp png_ptr
)
884 png_debug(1, "in png_set_tRNS_to_alpha");
886 png_ptr
->transformations
|= (PNG_EXPAND
| PNG_EXPAND_tRNS
);
887 png_ptr
->flags
&= ~PNG_FLAG_ROW_INIT
;
889 #endif /* defined(PNG_READ_EXPAND_SUPPORTED) */
891 #ifdef PNG_READ_EXPAND_16_SUPPORTED
892 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
893 * it may not work correctly.)
896 png_set_expand_16(png_structp png_ptr
)
898 png_debug(1, "in png_set_expand_16");
903 png_ptr
->transformations
|= (PNG_EXPAND_16
| PNG_EXPAND
| PNG_EXPAND_tRNS
);
904 png_ptr
->flags
&= ~PNG_FLAG_ROW_INIT
;
906 /* New API, make sure apps call the correct initializers: */
907 png_ptr
->flags
|= PNG_FLAG_DETECT_UNINITIALIZED
;
911 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
913 png_set_gray_to_rgb(png_structp png_ptr
)
915 png_debug(1, "in png_set_gray_to_rgb");
919 /* Because rgb must be 8 bits or more: */
920 png_set_expand_gray_1_2_4_to_8(png_ptr
);
921 png_ptr
->transformations
|= PNG_GRAY_TO_RGB
;
922 png_ptr
->flags
&= ~PNG_FLAG_ROW_INIT
;
927 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
929 png_set_rgb_to_gray_fixed(png_structp png_ptr
, int error_action
,
930 png_fixed_point red
, png_fixed_point green
)
932 png_debug(1, "in png_set_rgb_to_gray");
939 case PNG_ERROR_ACTION_NONE
:
940 png_ptr
->transformations
|= PNG_RGB_TO_GRAY
;
943 case PNG_ERROR_ACTION_WARN
:
944 png_ptr
->transformations
|= PNG_RGB_TO_GRAY_WARN
;
947 case PNG_ERROR_ACTION_ERROR
:
948 png_ptr
->transformations
|= PNG_RGB_TO_GRAY_ERR
;
952 png_error(png_ptr
, "invalid error action to rgb_to_gray");
955 if (png_ptr
->color_type
== PNG_COLOR_TYPE_PALETTE
)
956 #ifdef PNG_READ_EXPAND_SUPPORTED
957 png_ptr
->transformations
|= PNG_EXPAND
;
961 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
963 png_ptr
->transformations
&= ~PNG_RGB_TO_GRAY
;
967 if (red
>= 0 && green
>= 0 && red
+ green
<= PNG_FP_1
)
969 png_uint_16 red_int
, green_int
;
971 /* NOTE: this calculation does not round, but this behavior is retained
972 * for consistency, the inaccuracy is very small. The code here always
973 * overwrites the coefficients, regardless of whether they have been
974 * defaulted or set already.
976 red_int
= (png_uint_16
)(((png_uint_32
)red
*32768)/100000);
977 green_int
= (png_uint_16
)(((png_uint_32
)green
*32768)/100000);
979 png_ptr
->rgb_to_gray_red_coeff
= red_int
;
980 png_ptr
->rgb_to_gray_green_coeff
= green_int
;
981 png_ptr
->rgb_to_gray_coefficients_set
= 1;
986 if (red
>= 0 && green
>= 0)
988 "ignoring out of range rgb_to_gray coefficients");
990 /* Use the defaults, from the cHRM chunk if set, else the historical
991 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
992 * png_do_rgb_to_gray for more discussion of the values. In this case
993 * the coefficients are not marked as 'set' and are not overwritten if
994 * something has already provided a default.
996 if (png_ptr
->rgb_to_gray_red_coeff
== 0 &&
997 png_ptr
->rgb_to_gray_green_coeff
== 0)
999 png_ptr
->rgb_to_gray_red_coeff
= 6968;
1000 png_ptr
->rgb_to_gray_green_coeff
= 23434;
1001 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1007 #ifdef PNG_FLOATING_POINT_SUPPORTED
1008 /* Convert a RGB image to a grayscale of the same width. This allows us,
1009 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1013 png_set_rgb_to_gray(png_structp png_ptr
, int error_action
, double red
,
1016 if (png_ptr
== NULL
)
1019 png_set_rgb_to_gray_fixed(png_ptr
, error_action
,
1020 png_fixed(png_ptr
, red
, "rgb to gray red coefficient"),
1021 png_fixed(png_ptr
, green
, "rgb to gray green coefficient"));
1023 #endif /* FLOATING POINT */
1027 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1028 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1030 png_set_read_user_transform_fn(png_structp png_ptr
, png_user_transform_ptr
1031 read_user_transform_fn
)
1033 png_debug(1, "in png_set_read_user_transform_fn");
1035 if (png_ptr
== NULL
)
1038 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1039 png_ptr
->transformations
|= PNG_USER_TRANSFORM
;
1040 png_ptr
->read_user_transform_fn
= read_user_transform_fn
;
1045 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1046 #ifdef PNG_READ_GAMMA_SUPPORTED
1047 /* In the case of gamma transformations only do transformations on images where
1048 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1049 * slows things down slightly, and also needlessly introduces small errors.
1051 static int /* PRIVATE */
1052 png_gamma_threshold(png_fixed_point screen_gamma
, png_fixed_point file_gamma
)
1054 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1055 * correction as a difference of the overall transform from 1.0
1057 * We want to compare the threshold with s*f - 1, if we get
1058 * overflow here it is because of wacky gamma values so we
1059 * turn on processing anyway.
1061 png_fixed_point gtest
;
1062 return !png_muldiv(>est
, screen_gamma
, file_gamma
, PNG_FP_1
) ||
1063 png_gamma_significant(gtest
);
1067 /* Initialize everything needed for the read. This includes modifying
1071 /*For the moment 'png_init_palette_transformations' and
1072 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1073 * The intent is that these two routines should have palette or rgb operations
1074 * extracted from 'png_init_read_transformations'.
1076 static void /* PRIVATE */
1077 png_init_palette_transformations(png_structp png_ptr
)
1079 /* Called to handle the (input) palette case. In png_do_read_transformations
1080 * the first step is to expand the palette if requested, so this code must
1081 * take care to only make changes that are invariant with respect to the
1082 * palette expansion, or only do them if there is no expansion.
1084 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1087 int input_has_alpha
= 0;
1088 int input_has_transparency
= 0;
1090 if (png_ptr
->num_trans
> 0)
1094 /* Ignore if all the entries are opaque (unlikely!) */
1095 for (i
=0; i
<png_ptr
->num_trans
; ++i
)
1096 if (png_ptr
->trans_alpha
[i
] == 255)
1098 else if (png_ptr
->trans_alpha
[i
] == 0)
1099 input_has_transparency
= 1;
1101 input_has_alpha
= 1;
1104 /* If no alpha we can optimize. */
1105 if (!input_has_alpha
)
1107 /* Any alpha means background and associative alpha processing is
1108 * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
1109 * and ENCODE_ALPHA are irrelevant.
1111 png_ptr
->transformations
&= ~PNG_ENCODE_ALPHA
;
1112 png_ptr
->flags
&= ~PNG_FLAG_OPTIMIZE_ALPHA
;
1114 if (!input_has_transparency
)
1115 png_ptr
->transformations
&= ~(PNG_COMPOSE
| PNG_BACKGROUND_EXPAND
);
1118 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1119 /* png_set_background handling - deals with the complexity of whether the
1120 * background color is in the file format or the screen format in the case
1121 * where an 'expand' will happen.
1124 /* The following code cannot be entered in the alpha pre-multiplication case
1125 * because PNG_BACKGROUND_EXPAND is cancelled below.
1127 if ((png_ptr
->transformations
& PNG_BACKGROUND_EXPAND
) &&
1128 (png_ptr
->transformations
& PNG_EXPAND
))
1131 png_ptr
->background
.red
=
1132 png_ptr
->palette
[png_ptr
->background
.index
].red
;
1133 png_ptr
->background
.green
=
1134 png_ptr
->palette
[png_ptr
->background
.index
].green
;
1135 png_ptr
->background
.blue
=
1136 png_ptr
->palette
[png_ptr
->background
.index
].blue
;
1138 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1139 if (png_ptr
->transformations
& PNG_INVERT_ALPHA
)
1141 if (!(png_ptr
->transformations
& PNG_EXPAND_tRNS
))
1143 /* Invert the alpha channel (in tRNS) unless the pixels are
1144 * going to be expanded, in which case leave it for later
1146 int i
, istop
= png_ptr
->num_trans
;
1148 for (i
=0; i
<istop
; i
++)
1149 png_ptr
->trans_alpha
[i
] = (png_byte
)(255 -
1150 png_ptr
->trans_alpha
[i
]);
1153 #endif /* PNG_READ_INVERT_ALPHA_SUPPORTED */
1155 } /* background expand and (therefore) no alpha association. */
1156 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
1159 static void /* PRIVATE */
1160 png_init_rgb_transformations(png_structp png_ptr
)
1162 /* Added to libpng-1.5.4: check the color type to determine whether there
1163 * is any alpha or transparency in the image and simply cancel the
1164 * background and alpha mode stuff if there isn't.
1166 int input_has_alpha
= (png_ptr
->color_type
& PNG_COLOR_MASK_ALPHA
) != 0;
1167 int input_has_transparency
= png_ptr
->num_trans
> 0;
1169 /* If no alpha we can optimize. */
1170 if (!input_has_alpha
)
1172 /* Any alpha means background and associative alpha processing is
1173 * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
1174 * and ENCODE_ALPHA are irrelevant.
1176 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1177 png_ptr
->transformations
&= ~PNG_ENCODE_ALPHA
;
1178 png_ptr
->flags
&= ~PNG_FLAG_OPTIMIZE_ALPHA
;
1181 if (!input_has_transparency
)
1182 png_ptr
->transformations
&= ~(PNG_COMPOSE
| PNG_BACKGROUND_EXPAND
);
1185 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1186 /* png_set_background handling - deals with the complexity of whether the
1187 * background color is in the file format or the screen format in the case
1188 * where an 'expand' will happen.
1191 /* The following code cannot be entered in the alpha pre-multiplication case
1192 * because PNG_BACKGROUND_EXPAND is cancelled below.
1194 if ((png_ptr
->transformations
& PNG_BACKGROUND_EXPAND
) &&
1195 (png_ptr
->transformations
& PNG_EXPAND
) &&
1196 !(png_ptr
->color_type
& PNG_COLOR_MASK_COLOR
))
1197 /* i.e., GRAY or GRAY_ALPHA */
1200 /* Expand background and tRNS chunks */
1201 int gray
= png_ptr
->background
.gray
;
1202 int trans_gray
= png_ptr
->trans_color
.gray
;
1204 switch (png_ptr
->bit_depth
)
1224 /* Already 8 bits, fall through */
1227 /* Already a full 16 bits */
1231 png_ptr
->background
.red
= png_ptr
->background
.green
=
1232 png_ptr
->background
.blue
= (png_uint_16
)gray
;
1234 if (!(png_ptr
->transformations
& PNG_EXPAND_tRNS
))
1236 png_ptr
->trans_color
.red
= png_ptr
->trans_color
.green
=
1237 png_ptr
->trans_color
.blue
= (png_uint_16
)trans_gray
;
1240 } /* background expand and (therefore) no alpha association. */
1241 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
1245 png_init_read_transformations(png_structp png_ptr
)
1247 png_debug(1, "in png_init_read_transformations");
1249 /* This internal function is called from png_read_start_row in pngrutil.c
1250 * and it is called before the 'rowbytes' calculation is done, so the code
1251 * in here can change or update the transformations flags.
1253 * First do updates that do not depend on the details of the PNG image data
1257 #ifdef PNG_READ_GAMMA_SUPPORTED
1258 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1259 * png_set_alpha_mode and this is another source for a default file gamma so
1260 * the test needs to be performed later - here. In addition prior to 1.5.4
1261 * the tests were repeated for the PALETTE color type here - this is no
1262 * longer necessary (and doesn't seem to have been necessary before.)
1265 /* The following temporary indicates if overall gamma correction is
1268 int gamma_correction
= 0;
1270 if (png_ptr
->gamma
!= 0) /* has been set */
1272 if (png_ptr
->screen_gamma
!= 0) /* screen set too */
1273 gamma_correction
= png_gamma_threshold(png_ptr
->gamma
,
1274 png_ptr
->screen_gamma
);
1277 /* Assume the output matches the input; a long time default behavior
1278 * of libpng, although the standard has nothing to say about this.
1280 png_ptr
->screen_gamma
= png_reciprocal(png_ptr
->gamma
);
1283 else if (png_ptr
->screen_gamma
!= 0)
1284 /* The converse - assume the file matches the screen, note that this
1285 * perhaps undesireable default can (from 1.5.4) be changed by calling
1286 * png_set_alpha_mode (even if the alpha handling mode isn't required
1287 * or isn't changed from the default.)
1289 png_ptr
->gamma
= png_reciprocal(png_ptr
->screen_gamma
);
1291 else /* neither are set */
1292 /* Just in case the following prevents any processing - file and screen
1293 * are both assumed to be linear and there is no way to introduce a
1294 * third gamma value other than png_set_background with 'UNIQUE', and,
1297 png_ptr
->screen_gamma
= png_ptr
->gamma
= PNG_FP_1
;
1299 /* Now turn the gamma transformation on or off as appropriate. Notice
1300 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1301 * composition may independently cause gamma correction because it needs
1302 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1303 * hasn't been specified.) In any case this flag may get turned off in
1304 * the code immediately below if the transform can be handled outside the
1307 if (gamma_correction
)
1308 png_ptr
->transformations
|= PNG_GAMMA
;
1311 png_ptr
->transformations
&= ~PNG_GAMMA
;
1315 /* Certain transformations have the effect of preventing other
1316 * transformations that happen afterward in png_do_read_transformations,
1317 * resolve the interdependencies here. From the code of
1318 * png_do_read_transformations the order is:
1320 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1321 * 2) PNG_STRIP_ALPHA (if no compose)
1322 * 3) PNG_RGB_TO_GRAY
1323 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1326 * 7) PNG_STRIP_ALPHA (if compose)
1327 * 8) PNG_ENCODE_ALPHA
1328 * 9) PNG_SCALE_16_TO_8
1330 * 11) PNG_QUANTIZE (converts to palette)
1332 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1333 * 14) PNG_INVERT_MONO
1338 * 19) PNG_FILLER (includes PNG_ADD_ALPHA)
1339 * 20) PNG_INVERT_ALPHA
1340 * 21) PNG_SWAP_ALPHA
1341 * 22) PNG_SWAP_BYTES
1342 * 23) PNG_USER_TRANSFORM [must be last]
1344 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1345 if ((png_ptr
->transformations
& PNG_STRIP_ALPHA
) &&
1346 !(png_ptr
->transformations
& PNG_COMPOSE
))
1348 /* Stripping the alpha channel happens immediately after the 'expand'
1349 * transformations, before all other transformation, so it cancels out
1350 * the alpha handling. It has the side effect negating the effect of
1351 * PNG_EXPAND_tRNS too:
1353 png_ptr
->transformations
&= ~(PNG_BACKGROUND_EXPAND
| PNG_ENCODE_ALPHA
|
1355 png_ptr
->flags
&= ~PNG_FLAG_OPTIMIZE_ALPHA
;
1357 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1358 * so transparency information would remain just so long as it wasn't
1359 * expanded. This produces unexpected API changes if the set of things
1360 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1361 * documentation - which says ask for what you want, accept what you
1362 * get.) This makes the behavior consistent from 1.5.4:
1364 png_ptr
->num_trans
= 0;
1366 #endif /* STRIP_ALPHA supported, no COMPOSE */
1368 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1369 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1370 * settings will have no effect.
1372 if (!png_gamma_significant(png_ptr
->screen_gamma
))
1374 png_ptr
->transformations
&= ~PNG_ENCODE_ALPHA
;
1375 png_ptr
->flags
&= ~PNG_FLAG_OPTIMIZE_ALPHA
;
1379 #if defined(PNG_READ_EXPAND_SUPPORTED) && \
1380 defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1381 defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
1382 /* Detect gray background and attempt to enable optimization for
1383 * gray --> RGB case.
1385 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1386 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1387 * background color might actually be gray yet not be flagged as such.
1388 * This is not a problem for the current code, which uses
1389 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1390 * png_do_gray_to_rgb() transformation.
1392 * TODO: this code needs to be revised to avoid the complexity and
1393 * interdependencies. The color type of the background should be recorded in
1394 * png_set_background, along with the bit depth, then the code has a record
1395 * of exactly what color space the background is currently in.
1397 if (png_ptr
->transformations
& PNG_BACKGROUND_EXPAND
)
1399 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1400 * the file was grayscale the background value is gray.
1402 if (!(png_ptr
->color_type
& PNG_COLOR_MASK_COLOR
))
1403 png_ptr
->mode
|= PNG_BACKGROUND_IS_GRAY
;
1406 else if (png_ptr
->transformations
& PNG_COMPOSE
)
1408 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1409 * so the color is in the color space of the output or png_set_alpha_mode
1410 * was called and the color is black. Ignore RGB_TO_GRAY because that
1411 * happens before GRAY_TO_RGB.
1413 if (png_ptr
->transformations
& PNG_GRAY_TO_RGB
)
1415 if (png_ptr
->background
.red
== png_ptr
->background
.green
&&
1416 png_ptr
->background
.red
== png_ptr
->background
.blue
)
1418 png_ptr
->mode
|= PNG_BACKGROUND_IS_GRAY
;
1419 png_ptr
->background
.gray
= png_ptr
->background
.red
;
1423 #endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED (etc) */
1425 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1426 * can be performed directly on the palette, and some (such as rgb to gray)
1427 * can be optimized inside the palette. This is particularly true of the
1428 * composite (background and alpha) stuff, which can be pretty much all done
1429 * in the palette even if the result is expanded to RGB or gray afterward.
1431 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1432 * earlier and the palette stuff is actually handled on the first row. This
1433 * leads to the reported bug that the palette returned by png_get_PLTE is not
1436 if (png_ptr
->color_type
== PNG_COLOR_TYPE_PALETTE
)
1437 png_init_palette_transformations(png_ptr
);
1440 png_init_rgb_transformations(png_ptr
);
1442 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1443 defined(PNG_READ_EXPAND_16_SUPPORTED)
1444 if ((png_ptr
->transformations
& PNG_EXPAND_16
) &&
1445 (png_ptr
->transformations
& PNG_COMPOSE
) &&
1446 !(png_ptr
->transformations
& PNG_BACKGROUND_EXPAND
) &&
1447 png_ptr
->bit_depth
!= 16)
1449 /* TODO: fix this. Because the expand_16 operation is after the compose
1450 * handling the background color must be 8, not 16, bits deep, but the
1451 * application will supply a 16-bit value so reduce it here.
1453 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1454 * present, so that case is ok (until do_expand_16 is moved.)
1456 * NOTE: this discards the low 16 bits of the user supplied background
1457 * color, but until expand_16 works properly there is no choice!
1459 # define CHOP(x) (x)=((png_uint_16)(((png_uint_32)(x)*255+32895) >> 16))
1460 CHOP(png_ptr
->background
.red
);
1461 CHOP(png_ptr
->background
.green
);
1462 CHOP(png_ptr
->background
.blue
);
1463 CHOP(png_ptr
->background
.gray
);
1466 #endif /* PNG_READ_BACKGROUND_SUPPORTED && PNG_READ_EXPAND_16_SUPPORTED */
1468 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1469 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1470 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1471 if ((png_ptr
->transformations
& (PNG_16_TO_8
|PNG_SCALE_16_TO_8
)) &&
1472 (png_ptr
->transformations
& PNG_COMPOSE
) &&
1473 !(png_ptr
->transformations
& PNG_BACKGROUND_EXPAND
) &&
1474 png_ptr
->bit_depth
== 16)
1476 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1477 * component this will also happen after PNG_COMPOSE and so the background
1478 * color must be pre-expanded here.
1480 * TODO: fix this too.
1482 png_ptr
->background
.red
= (png_uint_16
)(png_ptr
->background
.red
* 257);
1483 png_ptr
->background
.green
=
1484 (png_uint_16
)(png_ptr
->background
.green
* 257);
1485 png_ptr
->background
.blue
= (png_uint_16
)(png_ptr
->background
.blue
* 257);
1486 png_ptr
->background
.gray
= (png_uint_16
)(png_ptr
->background
.gray
* 257);
1490 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1491 * background support (see the comments in scripts/pnglibconf.dfa), this
1492 * allows pre-multiplication of the alpha channel to be implemented as
1493 * compositing on black. This is probably sub-optimal and has been done in
1494 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1495 * implement the new API quickly, without lots of internal changes.)
1498 #ifdef PNG_READ_GAMMA_SUPPORTED
1499 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1500 /* Includes ALPHA_MODE */
1501 png_ptr
->background_1
= png_ptr
->background
;
1504 /* This needs to change - in the palette image case a whole set of tables are
1505 * built when it would be quicker to just calculate the correct value for
1506 * each palette entry directly. Also, the test is too tricky - why check
1507 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1508 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1509 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1510 * the gamma tables will not be built even if composition is required on a
1511 * gamma encoded value.
1513 * In 1.5.4 this is addressed below by an additional check on the individual
1514 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1517 if ((png_ptr
->transformations
& PNG_GAMMA
)
1518 || ((png_ptr
->transformations
& PNG_RGB_TO_GRAY
)
1519 && (png_gamma_significant(png_ptr
->gamma
) ||
1520 png_gamma_significant(png_ptr
->screen_gamma
)))
1521 || ((png_ptr
->transformations
& PNG_COMPOSE
)
1522 && (png_gamma_significant(png_ptr
->gamma
)
1523 || png_gamma_significant(png_ptr
->screen_gamma
)
1524 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1525 || (png_ptr
->background_gamma_type
== PNG_BACKGROUND_GAMMA_UNIQUE
1526 && png_gamma_significant(png_ptr
->background_gamma
))
1528 )) || ((png_ptr
->transformations
& PNG_ENCODE_ALPHA
)
1529 && png_gamma_significant(png_ptr
->screen_gamma
))
1532 png_build_gamma_table(png_ptr
, png_ptr
->bit_depth
);
1534 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1535 if (png_ptr
->transformations
& PNG_COMPOSE
)
1537 /* Issue a warning about this combination: because RGB_TO_GRAY is
1538 * optimized to do the gamma transform if present yet do_background has
1539 * to do the same thing if both options are set a
1540 * double-gamma-correction happens. This is true in all versions of
1543 if (png_ptr
->transformations
& PNG_RGB_TO_GRAY
)
1544 png_warning(png_ptr
,
1545 "libpng does not support gamma+background+rgb_to_gray");
1547 if (png_ptr
->color_type
== PNG_COLOR_TYPE_PALETTE
)
1549 /* We don't get to here unless there is a tRNS chunk with non-opaque
1550 * entries - see the checking code at the start of this function.
1552 png_color back
, back_1
;
1553 png_colorp palette
= png_ptr
->palette
;
1554 int num_palette
= png_ptr
->num_palette
;
1556 if (png_ptr
->background_gamma_type
== PNG_BACKGROUND_GAMMA_FILE
)
1559 back
.red
= png_ptr
->gamma_table
[png_ptr
->background
.red
];
1560 back
.green
= png_ptr
->gamma_table
[png_ptr
->background
.green
];
1561 back
.blue
= png_ptr
->gamma_table
[png_ptr
->background
.blue
];
1563 back_1
.red
= png_ptr
->gamma_to_1
[png_ptr
->background
.red
];
1564 back_1
.green
= png_ptr
->gamma_to_1
[png_ptr
->background
.green
];
1565 back_1
.blue
= png_ptr
->gamma_to_1
[png_ptr
->background
.blue
];
1569 png_fixed_point g
, gs
;
1571 switch (png_ptr
->background_gamma_type
)
1573 case PNG_BACKGROUND_GAMMA_SCREEN
:
1574 g
= (png_ptr
->screen_gamma
);
1578 case PNG_BACKGROUND_GAMMA_FILE
:
1579 g
= png_reciprocal(png_ptr
->gamma
);
1580 gs
= png_reciprocal2(png_ptr
->gamma
,
1581 png_ptr
->screen_gamma
);
1584 case PNG_BACKGROUND_GAMMA_UNIQUE
:
1585 g
= png_reciprocal(png_ptr
->background_gamma
);
1586 gs
= png_reciprocal2(png_ptr
->background_gamma
,
1587 png_ptr
->screen_gamma
);
1590 g
= PNG_FP_1
; /* back_1 */
1591 gs
= PNG_FP_1
; /* back */
1595 if (png_gamma_significant(gs
))
1597 back
.red
= png_gamma_8bit_correct(png_ptr
->background
.red
,
1599 back
.green
= png_gamma_8bit_correct(png_ptr
->background
.green
,
1601 back
.blue
= png_gamma_8bit_correct(png_ptr
->background
.blue
,
1607 back
.red
= (png_byte
)png_ptr
->background
.red
;
1608 back
.green
= (png_byte
)png_ptr
->background
.green
;
1609 back
.blue
= (png_byte
)png_ptr
->background
.blue
;
1612 if (png_gamma_significant(g
))
1614 back_1
.red
= png_gamma_8bit_correct(png_ptr
->background
.red
,
1616 back_1
.green
= png_gamma_8bit_correct(
1617 png_ptr
->background
.green
, g
);
1618 back_1
.blue
= png_gamma_8bit_correct(png_ptr
->background
.blue
,
1624 back_1
.red
= (png_byte
)png_ptr
->background
.red
;
1625 back_1
.green
= (png_byte
)png_ptr
->background
.green
;
1626 back_1
.blue
= (png_byte
)png_ptr
->background
.blue
;
1630 for (i
= 0; i
< num_palette
; i
++)
1632 if (i
< (int)png_ptr
->num_trans
&&
1633 png_ptr
->trans_alpha
[i
] != 0xff)
1635 if (png_ptr
->trans_alpha
[i
] == 0)
1639 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1643 v
= png_ptr
->gamma_to_1
[palette
[i
].red
];
1644 png_composite(w
, v
, png_ptr
->trans_alpha
[i
], back_1
.red
);
1645 palette
[i
].red
= png_ptr
->gamma_from_1
[w
];
1647 v
= png_ptr
->gamma_to_1
[palette
[i
].green
];
1648 png_composite(w
, v
, png_ptr
->trans_alpha
[i
], back_1
.green
);
1649 palette
[i
].green
= png_ptr
->gamma_from_1
[w
];
1651 v
= png_ptr
->gamma_to_1
[palette
[i
].blue
];
1652 png_composite(w
, v
, png_ptr
->trans_alpha
[i
], back_1
.blue
);
1653 palette
[i
].blue
= png_ptr
->gamma_from_1
[w
];
1658 palette
[i
].red
= png_ptr
->gamma_table
[palette
[i
].red
];
1659 palette
[i
].green
= png_ptr
->gamma_table
[palette
[i
].green
];
1660 palette
[i
].blue
= png_ptr
->gamma_table
[palette
[i
].blue
];
1664 /* Prevent the transformations being done again.
1666 * NOTE: this is highly dubious; it removes the transformations in
1667 * place. This seems inconsistent with the general treatment of the
1668 * transformations elsewhere.
1670 png_ptr
->transformations
&= ~(PNG_COMPOSE
| PNG_GAMMA
);
1671 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1673 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1674 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1677 png_fixed_point g
= PNG_FP_1
; /* Correction to linear */
1678 png_fixed_point gs
= PNG_FP_1
; /* Correction to screen */
1680 switch (png_ptr
->background_gamma_type
)
1682 case PNG_BACKGROUND_GAMMA_SCREEN
:
1683 g
= png_ptr
->screen_gamma
;
1684 /* gs = PNG_FP_1; */
1687 case PNG_BACKGROUND_GAMMA_FILE
:
1688 g
= png_reciprocal(png_ptr
->gamma
);
1689 gs
= png_reciprocal2(png_ptr
->gamma
, png_ptr
->screen_gamma
);
1692 case PNG_BACKGROUND_GAMMA_UNIQUE
:
1693 g
= png_reciprocal(png_ptr
->background_gamma
);
1694 gs
= png_reciprocal2(png_ptr
->background_gamma
,
1695 png_ptr
->screen_gamma
);
1699 png_error(png_ptr
, "invalid background gamma type");
1702 g_sig
= png_gamma_significant(g
);
1703 gs_sig
= png_gamma_significant(gs
);
1706 png_ptr
->background_1
.gray
= png_gamma_correct(png_ptr
,
1707 png_ptr
->background
.gray
, g
);
1710 png_ptr
->background
.gray
= png_gamma_correct(png_ptr
,
1711 png_ptr
->background
.gray
, gs
);
1713 if ((png_ptr
->background
.red
!= png_ptr
->background
.green
) ||
1714 (png_ptr
->background
.red
!= png_ptr
->background
.blue
) ||
1715 (png_ptr
->background
.red
!= png_ptr
->background
.gray
))
1717 /* RGB or RGBA with color background */
1720 png_ptr
->background_1
.red
= png_gamma_correct(png_ptr
,
1721 png_ptr
->background
.red
, g
);
1723 png_ptr
->background_1
.green
= png_gamma_correct(png_ptr
,
1724 png_ptr
->background
.green
, g
);
1726 png_ptr
->background_1
.blue
= png_gamma_correct(png_ptr
,
1727 png_ptr
->background
.blue
, g
);
1732 png_ptr
->background
.red
= png_gamma_correct(png_ptr
,
1733 png_ptr
->background
.red
, gs
);
1735 png_ptr
->background
.green
= png_gamma_correct(png_ptr
,
1736 png_ptr
->background
.green
, gs
);
1738 png_ptr
->background
.blue
= png_gamma_correct(png_ptr
,
1739 png_ptr
->background
.blue
, gs
);
1745 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1746 png_ptr
->background_1
.red
= png_ptr
->background_1
.green
1747 = png_ptr
->background_1
.blue
= png_ptr
->background_1
.gray
;
1749 png_ptr
->background
.red
= png_ptr
->background
.green
1750 = png_ptr
->background
.blue
= png_ptr
->background
.gray
;
1753 /* The background is now in screen gamma: */
1754 png_ptr
->background_gamma_type
= PNG_BACKGROUND_GAMMA_SCREEN
;
1755 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1756 }/* png_ptr->transformations & PNG_BACKGROUND */
1759 /* Transformation does not include PNG_BACKGROUND */
1760 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
1761 if (png_ptr
->color_type
== PNG_COLOR_TYPE_PALETTE
1762 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1763 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1764 && ((png_ptr
->transformations
& PNG_EXPAND
) == 0 ||
1765 (png_ptr
->transformations
& PNG_RGB_TO_GRAY
) == 0)
1769 png_colorp palette
= png_ptr
->palette
;
1770 int num_palette
= png_ptr
->num_palette
;
1773 /*NOTE: there are other transformations that should probably be in here
1776 for (i
= 0; i
< num_palette
; i
++)
1778 palette
[i
].red
= png_ptr
->gamma_table
[palette
[i
].red
];
1779 palette
[i
].green
= png_ptr
->gamma_table
[palette
[i
].green
];
1780 palette
[i
].blue
= png_ptr
->gamma_table
[palette
[i
].blue
];
1783 /* Done the gamma correction. */
1784 png_ptr
->transformations
&= ~PNG_GAMMA
;
1785 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1787 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1790 #endif /* PNG_READ_GAMMA_SUPPORTED */
1792 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1793 /* No GAMMA transformation (see the hanging else 4 lines above) */
1794 if ((png_ptr
->transformations
& PNG_COMPOSE
) &&
1795 (png_ptr
->color_type
== PNG_COLOR_TYPE_PALETTE
))
1798 int istop
= (int)png_ptr
->num_trans
;
1800 png_colorp palette
= png_ptr
->palette
;
1802 back
.red
= (png_byte
)png_ptr
->background
.red
;
1803 back
.green
= (png_byte
)png_ptr
->background
.green
;
1804 back
.blue
= (png_byte
)png_ptr
->background
.blue
;
1806 for (i
= 0; i
< istop
; i
++)
1808 if (png_ptr
->trans_alpha
[i
] == 0)
1813 else if (png_ptr
->trans_alpha
[i
] != 0xff)
1815 /* The png_composite() macro is defined in png.h */
1816 png_composite(palette
[i
].red
, palette
[i
].red
,
1817 png_ptr
->trans_alpha
[i
], back
.red
);
1819 png_composite(palette
[i
].green
, palette
[i
].green
,
1820 png_ptr
->trans_alpha
[i
], back
.green
);
1822 png_composite(palette
[i
].blue
, palette
[i
].blue
,
1823 png_ptr
->trans_alpha
[i
], back
.blue
);
1827 png_ptr
->transformations
&= ~PNG_COMPOSE
;
1829 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
1831 #ifdef PNG_READ_SHIFT_SUPPORTED
1832 if ((png_ptr
->transformations
& PNG_SHIFT
) &&
1833 !(png_ptr
->transformations
& PNG_EXPAND
) &&
1834 (png_ptr
->color_type
== PNG_COLOR_TYPE_PALETTE
))
1837 int istop
= png_ptr
->num_palette
;
1838 int shift
= 8 - png_ptr
->sig_bit
.red
;
1840 png_ptr
->transformations
&= ~PNG_SHIFT
;
1842 /* significant bits can be in the range 1 to 7 for a meaninful result, if
1843 * the number of significant bits is 0 then no shift is done (this is an
1844 * error condition which is silently ignored.)
1846 if (shift
> 0 && shift
< 8) for (i
=0; i
<istop
; ++i
)
1848 int component
= png_ptr
->palette
[i
].red
;
1850 component
>>= shift
;
1851 png_ptr
->palette
[i
].red
= (png_byte
)component
;
1854 shift
= 8 - png_ptr
->sig_bit
.green
;
1855 if (shift
> 0 && shift
< 8) for (i
=0; i
<istop
; ++i
)
1857 int component
= png_ptr
->palette
[i
].green
;
1859 component
>>= shift
;
1860 png_ptr
->palette
[i
].green
= (png_byte
)component
;
1863 shift
= 8 - png_ptr
->sig_bit
.blue
;
1864 if (shift
> 0 && shift
< 8) for (i
=0; i
<istop
; ++i
)
1866 int component
= png_ptr
->palette
[i
].blue
;
1868 component
>>= shift
;
1869 png_ptr
->palette
[i
].blue
= (png_byte
)component
;
1872 #endif /* PNG_READ_SHIFT_SUPPORTED */
1875 /* Modify the info structure to reflect the transformations. The
1876 * info should be updated so a PNG file could be written with it,
1877 * assuming the transformations result in valid PNG data.
1880 png_read_transform_info(png_structp png_ptr
, png_infop info_ptr
)
1882 png_debug(1, "in png_read_transform_info");
1884 #ifdef PNG_READ_EXPAND_SUPPORTED
1885 if (png_ptr
->transformations
& PNG_EXPAND
)
1887 if (info_ptr
->color_type
== PNG_COLOR_TYPE_PALETTE
)
1889 /* This check must match what actually happens in
1890 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1891 * it is all opaque we must do the same (at present it does not.)
1893 if (png_ptr
->num_trans
> 0)
1894 info_ptr
->color_type
= PNG_COLOR_TYPE_RGB_ALPHA
;
1897 info_ptr
->color_type
= PNG_COLOR_TYPE_RGB
;
1899 info_ptr
->bit_depth
= 8;
1900 info_ptr
->num_trans
= 0;
1904 if (png_ptr
->num_trans
)
1906 if (png_ptr
->transformations
& PNG_EXPAND_tRNS
)
1907 info_ptr
->color_type
|= PNG_COLOR_MASK_ALPHA
;
1909 if (info_ptr
->bit_depth
< 8)
1910 info_ptr
->bit_depth
= 8;
1912 info_ptr
->num_trans
= 0;
1917 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
1918 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1919 /* The following is almost certainly wrong unless the background value is in
1922 if (png_ptr
->transformations
& PNG_COMPOSE
)
1923 info_ptr
->background
= png_ptr
->background
;
1926 #ifdef PNG_READ_GAMMA_SUPPORTED
1927 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
1928 * however it seems that the code in png_init_read_transformations, which has
1929 * been called before this from png_read_update_info->png_read_start_row
1930 * sometimes does the gamma transform and cancels the flag.
1932 info_ptr
->gamma
= png_ptr
->gamma
;
1935 if (info_ptr
->bit_depth
== 16)
1937 # ifdef PNG_READ_16BIT_SUPPORTED
1938 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1939 if (png_ptr
->transformations
& PNG_SCALE_16_TO_8
)
1940 info_ptr
->bit_depth
= 8;
1943 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1944 if (png_ptr
->transformations
& PNG_16_TO_8
)
1945 info_ptr
->bit_depth
= 8;
1949 /* No 16 bit support: force chopping 16-bit input down to 8, in this case
1950 * the app program can chose if both APIs are available by setting the
1951 * correct scaling to use.
1953 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1954 /* For compatibility with previous versions use the strip method by
1955 * default. This code works because if PNG_SCALE_16_TO_8 is already
1956 * set the code below will do that in preference to the chop.
1958 png_ptr
->transformations
|= PNG_16_TO_8
;
1959 info_ptr
->bit_depth
= 8;
1962 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1963 png_ptr
->transformations
|= PNG_SCALE_16_TO_8
;
1964 info_ptr
->bit_depth
= 8;
1967 CONFIGURATION ERROR
: you must enable at least one
16 to
8 method
1970 #endif /* !READ_16BIT_SUPPORTED */
1973 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1974 if (png_ptr
->transformations
& PNG_GRAY_TO_RGB
)
1975 info_ptr
->color_type
= (png_byte
)(info_ptr
->color_type
|
1976 PNG_COLOR_MASK_COLOR
);
1979 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1980 if (png_ptr
->transformations
& PNG_RGB_TO_GRAY
)
1981 info_ptr
->color_type
= (png_byte
)(info_ptr
->color_type
&
1982 ~PNG_COLOR_MASK_COLOR
);
1985 #ifdef PNG_READ_QUANTIZE_SUPPORTED
1986 if (png_ptr
->transformations
& PNG_QUANTIZE
)
1988 if (((info_ptr
->color_type
== PNG_COLOR_TYPE_RGB
) ||
1989 (info_ptr
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
)) &&
1990 png_ptr
->palette_lookup
&& info_ptr
->bit_depth
== 8)
1992 info_ptr
->color_type
= PNG_COLOR_TYPE_PALETTE
;
1997 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1998 if (png_ptr
->transformations
& PNG_EXPAND_16
&& info_ptr
->bit_depth
== 8 &&
1999 info_ptr
->color_type
!= PNG_COLOR_TYPE_PALETTE
)
2001 info_ptr
->bit_depth
= 16;
2005 #ifdef PNG_READ_PACK_SUPPORTED
2006 if ((png_ptr
->transformations
& PNG_PACK
) && (info_ptr
->bit_depth
< 8))
2007 info_ptr
->bit_depth
= 8;
2010 if (info_ptr
->color_type
== PNG_COLOR_TYPE_PALETTE
)
2011 info_ptr
->channels
= 1;
2013 else if (info_ptr
->color_type
& PNG_COLOR_MASK_COLOR
)
2014 info_ptr
->channels
= 3;
2017 info_ptr
->channels
= 1;
2019 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2020 if (png_ptr
->transformations
& PNG_STRIP_ALPHA
)
2022 info_ptr
->color_type
= (png_byte
)(info_ptr
->color_type
&
2023 ~PNG_COLOR_MASK_ALPHA
);
2024 info_ptr
->num_trans
= 0;
2028 if (info_ptr
->color_type
& PNG_COLOR_MASK_ALPHA
)
2029 info_ptr
->channels
++;
2031 #ifdef PNG_READ_FILLER_SUPPORTED
2032 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2033 if ((png_ptr
->transformations
& PNG_FILLER
) &&
2034 ((info_ptr
->color_type
== PNG_COLOR_TYPE_RGB
) ||
2035 (info_ptr
->color_type
== PNG_COLOR_TYPE_GRAY
)))
2037 info_ptr
->channels
++;
2038 /* If adding a true alpha channel not just filler */
2039 if (png_ptr
->transformations
& PNG_ADD_ALPHA
)
2040 info_ptr
->color_type
|= PNG_COLOR_MASK_ALPHA
;
2044 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2045 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2046 if (png_ptr
->transformations
& PNG_USER_TRANSFORM
)
2048 if (info_ptr
->bit_depth
< png_ptr
->user_transform_depth
)
2049 info_ptr
->bit_depth
= png_ptr
->user_transform_depth
;
2051 if (info_ptr
->channels
< png_ptr
->user_transform_channels
)
2052 info_ptr
->channels
= png_ptr
->user_transform_channels
;
2056 info_ptr
->pixel_depth
= (png_byte
)(info_ptr
->channels
*
2057 info_ptr
->bit_depth
);
2059 info_ptr
->rowbytes
= PNG_ROWBYTES(info_ptr
->pixel_depth
, info_ptr
->width
);
2061 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2062 * check in png_rowbytes that the user buffer won't get overwritten. Note
2063 * that the field is not always set - if png_read_update_info isn't called
2064 * the application has to either not do any transforms or get the calculation
2067 png_ptr
->info_rowbytes
= info_ptr
->rowbytes
;
2069 #ifndef PNG_READ_EXPAND_SUPPORTED
2075 /* Transform the row. The order of transformations is significant,
2076 * and is very touchy. If you add a transformation, take care to
2077 * decide how it fits in with the other transformations here.
2080 png_do_read_transformations(png_structp png_ptr
, png_row_infop row_info
)
2082 png_debug(1, "in png_do_read_transformations");
2084 if (png_ptr
->row_buf
== NULL
)
2086 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
2087 * error is incredibly rare and incredibly easy to debug without this
2090 png_error(png_ptr
, "NULL row buffer");
2093 /* The following is debugging; prior to 1.5.4 the code was never compiled in;
2094 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
2095 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.5 the new flag is set only for
2096 * selected new APIs to ensure that there is no API change.
2098 if ((png_ptr
->flags
& PNG_FLAG_DETECT_UNINITIALIZED
) != 0 &&
2099 !(png_ptr
->flags
& PNG_FLAG_ROW_INIT
))
2101 /* Application has failed to call either png_read_start_image() or
2102 * png_read_update_info() after setting transforms that expand pixels.
2103 * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
2105 png_error(png_ptr
, "Uninitialized row");
2108 #ifdef PNG_READ_EXPAND_SUPPORTED
2109 if (png_ptr
->transformations
& PNG_EXPAND
)
2111 if (row_info
->color_type
== PNG_COLOR_TYPE_PALETTE
)
2113 png_do_expand_palette(row_info
, png_ptr
->row_buf
+ 1,
2114 png_ptr
->palette
, png_ptr
->trans_alpha
, png_ptr
->num_trans
);
2119 if (png_ptr
->num_trans
&&
2120 (png_ptr
->transformations
& PNG_EXPAND_tRNS
))
2121 png_do_expand(row_info
, png_ptr
->row_buf
+ 1,
2122 &(png_ptr
->trans_color
));
2125 png_do_expand(row_info
, png_ptr
->row_buf
+ 1,
2131 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2132 if ((png_ptr
->transformations
& PNG_STRIP_ALPHA
) &&
2133 !(png_ptr
->transformations
& PNG_COMPOSE
) &&
2134 (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
||
2135 row_info
->color_type
== PNG_COLOR_TYPE_GRAY_ALPHA
))
2136 png_do_strip_channel(row_info
, png_ptr
->row_buf
+ 1,
2137 0 /* at_start == false, because SWAP_ALPHA happens later */);
2140 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2141 if (png_ptr
->transformations
& PNG_RGB_TO_GRAY
)
2144 png_do_rgb_to_gray(png_ptr
, row_info
,
2145 png_ptr
->row_buf
+ 1);
2149 png_ptr
->rgb_to_gray_status
=1;
2150 if ((png_ptr
->transformations
& PNG_RGB_TO_GRAY
) ==
2151 PNG_RGB_TO_GRAY_WARN
)
2152 png_warning(png_ptr
, "png_do_rgb_to_gray found nongray pixel");
2154 if ((png_ptr
->transformations
& PNG_RGB_TO_GRAY
) ==
2155 PNG_RGB_TO_GRAY_ERR
)
2156 png_error(png_ptr
, "png_do_rgb_to_gray found nongray pixel");
2161 /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
2163 * In most cases, the "simple transparency" should be done prior to doing
2164 * gray-to-RGB, or you will have to test 3x as many bytes to check if a
2165 * pixel is transparent. You would also need to make sure that the
2166 * transparency information is upgraded to RGB.
2168 * To summarize, the current flow is:
2169 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
2170 * with background "in place" if transparent,
2171 * convert to RGB if necessary
2172 * - Gray + alpha -> composite with gray background and remove alpha bytes,
2173 * convert to RGB if necessary
2175 * To support RGB backgrounds for gray images we need:
2176 * - Gray + simple transparency -> convert to RGB + simple transparency,
2177 * compare 3 or 6 bytes and composite with
2178 * background "in place" if transparent
2179 * (3x compare/pixel compared to doing
2180 * composite with gray bkgrnd)
2181 * - Gray + alpha -> convert to RGB + alpha, composite with background and
2182 * remove alpha bytes (3x float
2183 * operations/pixel compared with composite
2184 * on gray background)
2186 * Greg's change will do this. The reason it wasn't done before is for
2187 * performance, as this increases the per-pixel operations. If we would check
2188 * in advance if the background was gray or RGB, and position the gray-to-RGB
2189 * transform appropriately, then it would save a lot of work/time.
2192 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2193 /* If gray -> RGB, do so now only if background is non-gray; else do later
2194 * for performance reasons
2196 if ((png_ptr
->transformations
& PNG_GRAY_TO_RGB
) &&
2197 !(png_ptr
->mode
& PNG_BACKGROUND_IS_GRAY
))
2198 png_do_gray_to_rgb(row_info
, png_ptr
->row_buf
+ 1);
2201 #if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
2202 (defined PNG_READ_ALPHA_MODE_SUPPORTED)
2203 if (png_ptr
->transformations
& PNG_COMPOSE
)
2204 png_do_compose(row_info
, png_ptr
->row_buf
+ 1, png_ptr
);
2207 #ifdef PNG_READ_GAMMA_SUPPORTED
2208 if ((png_ptr
->transformations
& PNG_GAMMA
) &&
2209 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2210 /* Because RGB_TO_GRAY does the gamma transform. */
2211 !(png_ptr
->transformations
& PNG_RGB_TO_GRAY
) &&
2213 #if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
2214 (defined PNG_READ_ALPHA_MODE_SUPPORTED)
2215 /* Because PNG_COMPOSE does the gamma transform if there is something to
2216 * do (if there is an alpha channel or transparency.)
2218 !((png_ptr
->transformations
& PNG_COMPOSE
) &&
2219 ((png_ptr
->num_trans
!= 0) ||
2220 (png_ptr
->color_type
& PNG_COLOR_MASK_ALPHA
))) &&
2222 /* Because png_init_read_transformations transforms the palette, unless
2223 * RGB_TO_GRAY will do the transform.
2225 (png_ptr
->color_type
!= PNG_COLOR_TYPE_PALETTE
))
2226 png_do_gamma(row_info
, png_ptr
->row_buf
+ 1, png_ptr
);
2229 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2230 if ((png_ptr
->transformations
& PNG_STRIP_ALPHA
) &&
2231 (png_ptr
->transformations
& PNG_COMPOSE
) &&
2232 (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
||
2233 row_info
->color_type
== PNG_COLOR_TYPE_GRAY_ALPHA
))
2234 png_do_strip_channel(row_info
, png_ptr
->row_buf
+ 1,
2235 0 /* at_start == false, because SWAP_ALPHA happens later */);
2238 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
2239 if ((png_ptr
->transformations
& PNG_ENCODE_ALPHA
) &&
2240 (row_info
->color_type
& PNG_COLOR_MASK_ALPHA
))
2241 png_do_encode_alpha(row_info
, png_ptr
->row_buf
+ 1, png_ptr
);
2244 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2245 if (png_ptr
->transformations
& PNG_SCALE_16_TO_8
)
2246 png_do_scale_16_to_8(row_info
, png_ptr
->row_buf
+ 1);
2249 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2250 /* There is no harm in doing both of these because only one has any effect,
2251 * by putting the 'scale' option first if the app asks for scale (either by
2252 * calling the API or in a TRANSFORM flag) this is what happens.
2254 if (png_ptr
->transformations
& PNG_16_TO_8
)
2255 png_do_chop(row_info
, png_ptr
->row_buf
+ 1);
2258 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2259 if (png_ptr
->transformations
& PNG_QUANTIZE
)
2261 png_do_quantize(row_info
, png_ptr
->row_buf
+ 1,
2262 png_ptr
->palette_lookup
, png_ptr
->quantize_index
);
2264 if (row_info
->rowbytes
== 0)
2265 png_error(png_ptr
, "png_do_quantize returned rowbytes=0");
2267 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
2269 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2270 /* Do the expansion now, after all the arithmetic has been done. Notice
2271 * that previous transformations can handle the PNG_EXPAND_16 flag if this
2272 * is efficient (particularly true in the case of gamma correction, where
2273 * better accuracy results faster!)
2275 if (png_ptr
->transformations
& PNG_EXPAND_16
)
2276 png_do_expand_16(row_info
, png_ptr
->row_buf
+ 1);
2279 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2280 /*NOTE: moved here in 1.5.4 (from much later in this list.) */
2281 if ((png_ptr
->transformations
& PNG_GRAY_TO_RGB
) &&
2282 (png_ptr
->mode
& PNG_BACKGROUND_IS_GRAY
))
2283 png_do_gray_to_rgb(row_info
, png_ptr
->row_buf
+ 1);
2286 #ifdef PNG_READ_INVERT_SUPPORTED
2287 if (png_ptr
->transformations
& PNG_INVERT_MONO
)
2288 png_do_invert(row_info
, png_ptr
->row_buf
+ 1);
2291 #ifdef PNG_READ_SHIFT_SUPPORTED
2292 if (png_ptr
->transformations
& PNG_SHIFT
)
2293 png_do_unshift(row_info
, png_ptr
->row_buf
+ 1,
2297 #ifdef PNG_READ_PACK_SUPPORTED
2298 if (png_ptr
->transformations
& PNG_PACK
)
2299 png_do_unpack(row_info
, png_ptr
->row_buf
+ 1);
2302 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
2303 /* Added at libpng-1.5.10 */
2304 if (row_info
->color_type
== PNG_COLOR_TYPE_PALETTE
)
2305 png_do_check_palette_indexes(png_ptr
, row_info
);
2308 #ifdef PNG_READ_BGR_SUPPORTED
2309 if (png_ptr
->transformations
& PNG_BGR
)
2310 png_do_bgr(row_info
, png_ptr
->row_buf
+ 1);
2313 #ifdef PNG_READ_PACKSWAP_SUPPORTED
2314 if (png_ptr
->transformations
& PNG_PACKSWAP
)
2315 png_do_packswap(row_info
, png_ptr
->row_buf
+ 1);
2318 #ifdef PNG_READ_FILLER_SUPPORTED
2319 if (png_ptr
->transformations
& PNG_FILLER
)
2320 png_do_read_filler(row_info
, png_ptr
->row_buf
+ 1,
2321 (png_uint_32
)png_ptr
->filler
, png_ptr
->flags
);
2324 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2325 if (png_ptr
->transformations
& PNG_INVERT_ALPHA
)
2326 png_do_read_invert_alpha(row_info
, png_ptr
->row_buf
+ 1);
2329 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2330 if (png_ptr
->transformations
& PNG_SWAP_ALPHA
)
2331 png_do_read_swap_alpha(row_info
, png_ptr
->row_buf
+ 1);
2334 #ifdef PNG_READ_16BIT_SUPPORTED
2335 #ifdef PNG_READ_SWAP_SUPPORTED
2336 if (png_ptr
->transformations
& PNG_SWAP_BYTES
)
2337 png_do_swap(row_info
, png_ptr
->row_buf
+ 1);
2341 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
2342 if (png_ptr
->transformations
& PNG_USER_TRANSFORM
)
2344 if (png_ptr
->read_user_transform_fn
!= NULL
)
2345 (*(png_ptr
->read_user_transform_fn
)) /* User read transform function */
2346 (png_ptr
, /* png_ptr */
2347 row_info
, /* row_info: */
2348 /* png_uint_32 width; width of row */
2349 /* png_size_t rowbytes; number of bytes in row */
2350 /* png_byte color_type; color type of pixels */
2351 /* png_byte bit_depth; bit depth of samples */
2352 /* png_byte channels; number of channels (1-4) */
2353 /* png_byte pixel_depth; bits per pixel (depth*channels) */
2354 png_ptr
->row_buf
+ 1); /* start of pixel data for row */
2355 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
2356 if (png_ptr
->user_transform_depth
)
2357 row_info
->bit_depth
= png_ptr
->user_transform_depth
;
2359 if (png_ptr
->user_transform_channels
)
2360 row_info
->channels
= png_ptr
->user_transform_channels
;
2362 row_info
->pixel_depth
= (png_byte
)(row_info
->bit_depth
*
2363 row_info
->channels
);
2365 row_info
->rowbytes
= PNG_ROWBYTES(row_info
->pixel_depth
, row_info
->width
);
2370 #ifdef PNG_READ_PACK_SUPPORTED
2371 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2372 * without changing the actual values. Thus, if you had a row with
2373 * a bit depth of 1, you would end up with bytes that only contained
2374 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2375 * png_do_shift() after this.
2378 png_do_unpack(png_row_infop row_info
, png_bytep row
)
2380 png_debug(1, "in png_do_unpack");
2382 if (row_info
->bit_depth
< 8)
2385 png_uint_32 row_width
=row_info
->width
;
2387 switch (row_info
->bit_depth
)
2391 png_bytep sp
= row
+ (png_size_t
)((row_width
- 1) >> 3);
2392 png_bytep dp
= row
+ (png_size_t
)row_width
- 1;
2393 png_uint_32 shift
= 7 - (int)((row_width
+ 7) & 0x07);
2394 for (i
= 0; i
< row_width
; i
++)
2396 *dp
= (png_byte
)((*sp
>> shift
) & 0x01);
2415 png_bytep sp
= row
+ (png_size_t
)((row_width
- 1) >> 2);
2416 png_bytep dp
= row
+ (png_size_t
)row_width
- 1;
2417 png_uint_32 shift
= (int)((3 - ((row_width
+ 3) & 0x03)) << 1);
2418 for (i
= 0; i
< row_width
; i
++)
2420 *dp
= (png_byte
)((*sp
>> shift
) & 0x03);
2438 png_bytep sp
= row
+ (png_size_t
)((row_width
- 1) >> 1);
2439 png_bytep dp
= row
+ (png_size_t
)row_width
- 1;
2440 png_uint_32 shift
= (int)((1 - ((row_width
+ 1) & 0x01)) << 2);
2441 for (i
= 0; i
< row_width
; i
++)
2443 *dp
= (png_byte
)((*sp
>> shift
) & 0x0f);
2462 row_info
->bit_depth
= 8;
2463 row_info
->pixel_depth
= (png_byte
)(8 * row_info
->channels
);
2464 row_info
->rowbytes
= row_width
* row_info
->channels
;
2469 #ifdef PNG_READ_SHIFT_SUPPORTED
2470 /* Reverse the effects of png_do_shift. This routine merely shifts the
2471 * pixels back to their significant bits values. Thus, if you have
2472 * a row of bit depth 8, but only 5 are significant, this will shift
2473 * the values back to 0 through 31.
2476 png_do_unshift(png_row_infop row_info
, png_bytep row
,
2477 png_const_color_8p sig_bits
)
2481 png_debug(1, "in png_do_unshift");
2483 /* The palette case has already been handled in the _init routine. */
2484 color_type
= row_info
->color_type
;
2486 if (color_type
!= PNG_COLOR_TYPE_PALETTE
)
2490 int bit_depth
= row_info
->bit_depth
;
2492 if (color_type
& PNG_COLOR_MASK_COLOR
)
2494 shift
[channels
++] = bit_depth
- sig_bits
->red
;
2495 shift
[channels
++] = bit_depth
- sig_bits
->green
;
2496 shift
[channels
++] = bit_depth
- sig_bits
->blue
;
2501 shift
[channels
++] = bit_depth
- sig_bits
->gray
;
2504 if (color_type
& PNG_COLOR_MASK_ALPHA
)
2506 shift
[channels
++] = bit_depth
- sig_bits
->alpha
;
2512 for (c
= have_shift
= 0; c
< channels
; ++c
)
2514 /* A shift of more than the bit depth is an error condition but it
2515 * gets ignored here.
2517 if (shift
[c
] <= 0 || shift
[c
] >= bit_depth
)
2531 /* Must be 1bpp gray: should not be here! */
2536 /* Must be 2bpp gray */
2537 /* assert(channels == 1 && shift[0] == 1) */
2540 png_bytep bp_end
= bp
+ row_info
->rowbytes
;
2544 int b
= (*bp
>> 1) & 0x55;
2545 *bp
++ = (png_byte
)b
;
2551 /* Must be 4bpp gray */
2552 /* assert(channels == 1) */
2555 png_bytep bp_end
= bp
+ row_info
->rowbytes
;
2556 int gray_shift
= shift
[0];
2557 int mask
= 0xf >> gray_shift
;
2563 int b
= (*bp
>> gray_shift
) & mask
;
2564 *bp
++ = (png_byte
)b
;
2570 /* Single byte components, G, GA, RGB, RGBA */
2573 png_bytep bp_end
= bp
+ row_info
->rowbytes
;
2578 int b
= *bp
>> shift
[channel
];
2579 if (++channel
>= channels
)
2581 *bp
++ = (png_byte
)b
;
2586 #ifdef PNG_READ_16BIT_SUPPORTED
2588 /* Double byte components, G, GA, RGB, RGBA */
2591 png_bytep bp_end
= bp
+ row_info
->rowbytes
;
2596 int value
= (bp
[0] << 8) + bp
[1];
2598 value
>>= shift
[channel
];
2599 if (++channel
>= channels
)
2601 *bp
++ = (png_byte
)(value
>> 8);
2602 *bp
++ = (png_byte
)(value
& 0xff);
2612 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2613 /* Scale rows of bit depth 16 down to 8 accurately */
2615 png_do_scale_16_to_8(png_row_infop row_info
, png_bytep row
)
2617 png_debug(1, "in png_do_scale_16_to_8");
2619 if (row_info
->bit_depth
== 16)
2621 png_bytep sp
= row
; /* source */
2622 png_bytep dp
= row
; /* destination */
2623 png_bytep ep
= sp
+ row_info
->rowbytes
; /* end+1 */
2627 /* The input is an array of 16 bit components, these must be scaled to
2628 * 8 bits each. For a 16 bit value V the required value (from the PNG
2629 * specification) is:
2633 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2635 * Represent V as the two byte value vhi.vlo. Make a guess that the
2636 * result is the top byte of V, vhi, then the correction to this value
2639 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2640 * = floor(((vlo-vhi) + 128.5) / 257)
2642 * This can be approximated using integer arithmetic (and a signed
2645 * error = (vlo-vhi+128) >> 8;
2647 * The approximate differs from the exact answer only when (vlo-vhi) is
2648 * 128; it then gives a correction of +1 when the exact correction is
2649 * 0. This gives 128 errors. The exact answer (correct for all 16 bit
2652 * error = (vlo-vhi+128)*65535 >> 24;
2654 * An alternative arithmetic calculation which also gives no errors is:
2656 * (V * 255 + 32895) >> 16
2659 png_int_32 tmp
= *sp
++; /* must be signed! */
2660 tmp
+= (((int)*sp
++ - tmp
+ 128) * 65535) >> 24;
2661 *dp
++ = (png_byte
)tmp
;
2664 row_info
->bit_depth
= 8;
2665 row_info
->pixel_depth
= (png_byte
)(8 * row_info
->channels
);
2666 row_info
->rowbytes
= row_info
->width
* row_info
->channels
;
2671 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2673 /* Simply discard the low byte. This was the default behavior prior
2676 png_do_chop(png_row_infop row_info
, png_bytep row
)
2678 png_debug(1, "in png_do_chop");
2680 if (row_info
->bit_depth
== 16)
2682 png_bytep sp
= row
; /* source */
2683 png_bytep dp
= row
; /* destination */
2684 png_bytep ep
= sp
+ row_info
->rowbytes
; /* end+1 */
2689 sp
+= 2; /* skip low byte */
2692 row_info
->bit_depth
= 8;
2693 row_info
->pixel_depth
= (png_byte
)(8 * row_info
->channels
);
2694 row_info
->rowbytes
= row_info
->width
* row_info
->channels
;
2699 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2701 png_do_read_swap_alpha(png_row_infop row_info
, png_bytep row
)
2703 png_debug(1, "in png_do_read_swap_alpha");
2706 png_uint_32 row_width
= row_info
->width
;
2707 if (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
)
2709 /* This converts from RGBA to ARGB */
2710 if (row_info
->bit_depth
== 8)
2712 png_bytep sp
= row
+ row_info
->rowbytes
;
2717 for (i
= 0; i
< row_width
; i
++)
2727 #ifdef PNG_READ_16BIT_SUPPORTED
2728 /* This converts from RRGGBBAA to AARRGGBB */
2731 png_bytep sp
= row
+ row_info
->rowbytes
;
2736 for (i
= 0; i
< row_width
; i
++)
2753 else if (row_info
->color_type
== PNG_COLOR_TYPE_GRAY_ALPHA
)
2755 /* This converts from GA to AG */
2756 if (row_info
->bit_depth
== 8)
2758 png_bytep sp
= row
+ row_info
->rowbytes
;
2763 for (i
= 0; i
< row_width
; i
++)
2771 #ifdef PNG_READ_16BIT_SUPPORTED
2772 /* This converts from GGAA to AAGG */
2775 png_bytep sp
= row
+ row_info
->rowbytes
;
2780 for (i
= 0; i
< row_width
; i
++)
2796 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2798 png_do_read_invert_alpha(png_row_infop row_info
, png_bytep row
)
2800 png_uint_32 row_width
;
2801 png_debug(1, "in png_do_read_invert_alpha");
2803 row_width
= row_info
->width
;
2804 if (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
)
2806 if (row_info
->bit_depth
== 8)
2808 /* This inverts the alpha channel in RGBA */
2809 png_bytep sp
= row
+ row_info
->rowbytes
;
2813 for (i
= 0; i
< row_width
; i
++)
2815 *(--dp
) = (png_byte
)(255 - *(--sp
));
2817 /* This does nothing:
2821 We can replace it with:
2828 #ifdef PNG_READ_16BIT_SUPPORTED
2829 /* This inverts the alpha channel in RRGGBBAA */
2832 png_bytep sp
= row
+ row_info
->rowbytes
;
2836 for (i
= 0; i
< row_width
; i
++)
2838 *(--dp
) = (png_byte
)(255 - *(--sp
));
2839 *(--dp
) = (png_byte
)(255 - *(--sp
));
2841 /* This does nothing:
2848 We can replace it with:
2856 else if (row_info
->color_type
== PNG_COLOR_TYPE_GRAY_ALPHA
)
2858 if (row_info
->bit_depth
== 8)
2860 /* This inverts the alpha channel in GA */
2861 png_bytep sp
= row
+ row_info
->rowbytes
;
2865 for (i
= 0; i
< row_width
; i
++)
2867 *(--dp
) = (png_byte
)(255 - *(--sp
));
2872 #ifdef PNG_READ_16BIT_SUPPORTED
2875 /* This inverts the alpha channel in GGAA */
2876 png_bytep sp
= row
+ row_info
->rowbytes
;
2880 for (i
= 0; i
< row_width
; i
++)
2882 *(--dp
) = (png_byte
)(255 - *(--sp
));
2883 *(--dp
) = (png_byte
)(255 - *(--sp
));
2897 #ifdef PNG_READ_FILLER_SUPPORTED
2898 /* Add filler channel if we have RGB color */
2900 png_do_read_filler(png_row_infop row_info
, png_bytep row
,
2901 png_uint_32 filler
, png_uint_32 flags
)
2904 png_uint_32 row_width
= row_info
->width
;
2906 #ifdef PNG_READ_16BIT_SUPPORTED
2907 png_byte hi_filler
= (png_byte
)((filler
>>8) & 0xff);
2909 png_byte lo_filler
= (png_byte
)(filler
& 0xff);
2911 png_debug(1, "in png_do_read_filler");
2914 row_info
->color_type
== PNG_COLOR_TYPE_GRAY
)
2916 if (row_info
->bit_depth
== 8)
2918 if (flags
& PNG_FLAG_FILLER_AFTER
)
2920 /* This changes the data from G to GX */
2921 png_bytep sp
= row
+ (png_size_t
)row_width
;
2922 png_bytep dp
= sp
+ (png_size_t
)row_width
;
2923 for (i
= 1; i
< row_width
; i
++)
2925 *(--dp
) = lo_filler
;
2928 *(--dp
) = lo_filler
;
2929 row_info
->channels
= 2;
2930 row_info
->pixel_depth
= 16;
2931 row_info
->rowbytes
= row_width
* 2;
2936 /* This changes the data from G to XG */
2937 png_bytep sp
= row
+ (png_size_t
)row_width
;
2938 png_bytep dp
= sp
+ (png_size_t
)row_width
;
2939 for (i
= 0; i
< row_width
; i
++)
2942 *(--dp
) = lo_filler
;
2944 row_info
->channels
= 2;
2945 row_info
->pixel_depth
= 16;
2946 row_info
->rowbytes
= row_width
* 2;
2950 #ifdef PNG_READ_16BIT_SUPPORTED
2951 else if (row_info
->bit_depth
== 16)
2953 if (flags
& PNG_FLAG_FILLER_AFTER
)
2955 /* This changes the data from GG to GGXX */
2956 png_bytep sp
= row
+ (png_size_t
)row_width
* 2;
2957 png_bytep dp
= sp
+ (png_size_t
)row_width
* 2;
2958 for (i
= 1; i
< row_width
; i
++)
2960 *(--dp
) = hi_filler
;
2961 *(--dp
) = lo_filler
;
2965 *(--dp
) = hi_filler
;
2966 *(--dp
) = lo_filler
;
2967 row_info
->channels
= 2;
2968 row_info
->pixel_depth
= 32;
2969 row_info
->rowbytes
= row_width
* 4;
2974 /* This changes the data from GG to XXGG */
2975 png_bytep sp
= row
+ (png_size_t
)row_width
* 2;
2976 png_bytep dp
= sp
+ (png_size_t
)row_width
* 2;
2977 for (i
= 0; i
< row_width
; i
++)
2981 *(--dp
) = hi_filler
;
2982 *(--dp
) = lo_filler
;
2984 row_info
->channels
= 2;
2985 row_info
->pixel_depth
= 32;
2986 row_info
->rowbytes
= row_width
* 4;
2990 } /* COLOR_TYPE == GRAY */
2991 else if (row_info
->color_type
== PNG_COLOR_TYPE_RGB
)
2993 if (row_info
->bit_depth
== 8)
2995 if (flags
& PNG_FLAG_FILLER_AFTER
)
2997 /* This changes the data from RGB to RGBX */
2998 png_bytep sp
= row
+ (png_size_t
)row_width
* 3;
2999 png_bytep dp
= sp
+ (png_size_t
)row_width
;
3000 for (i
= 1; i
< row_width
; i
++)
3002 *(--dp
) = lo_filler
;
3007 *(--dp
) = lo_filler
;
3008 row_info
->channels
= 4;
3009 row_info
->pixel_depth
= 32;
3010 row_info
->rowbytes
= row_width
* 4;
3015 /* This changes the data from RGB to XRGB */
3016 png_bytep sp
= row
+ (png_size_t
)row_width
* 3;
3017 png_bytep dp
= sp
+ (png_size_t
)row_width
;
3018 for (i
= 0; i
< row_width
; i
++)
3023 *(--dp
) = lo_filler
;
3025 row_info
->channels
= 4;
3026 row_info
->pixel_depth
= 32;
3027 row_info
->rowbytes
= row_width
* 4;
3031 #ifdef PNG_READ_16BIT_SUPPORTED
3032 else if (row_info
->bit_depth
== 16)
3034 if (flags
& PNG_FLAG_FILLER_AFTER
)
3036 /* This changes the data from RRGGBB to RRGGBBXX */
3037 png_bytep sp
= row
+ (png_size_t
)row_width
* 6;
3038 png_bytep dp
= sp
+ (png_size_t
)row_width
* 2;
3039 for (i
= 1; i
< row_width
; i
++)
3041 *(--dp
) = hi_filler
;
3042 *(--dp
) = lo_filler
;
3050 *(--dp
) = hi_filler
;
3051 *(--dp
) = lo_filler
;
3052 row_info
->channels
= 4;
3053 row_info
->pixel_depth
= 64;
3054 row_info
->rowbytes
= row_width
* 8;
3059 /* This changes the data from RRGGBB to XXRRGGBB */
3060 png_bytep sp
= row
+ (png_size_t
)row_width
* 6;
3061 png_bytep dp
= sp
+ (png_size_t
)row_width
* 2;
3062 for (i
= 0; i
< row_width
; i
++)
3070 *(--dp
) = hi_filler
;
3071 *(--dp
) = lo_filler
;
3074 row_info
->channels
= 4;
3075 row_info
->pixel_depth
= 64;
3076 row_info
->rowbytes
= row_width
* 8;
3080 } /* COLOR_TYPE == RGB */
3084 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
3085 /* Expand grayscale files to RGB, with or without alpha */
3087 png_do_gray_to_rgb(png_row_infop row_info
, png_bytep row
)
3090 png_uint_32 row_width
= row_info
->width
;
3092 png_debug(1, "in png_do_gray_to_rgb");
3094 if (row_info
->bit_depth
>= 8 &&
3095 !(row_info
->color_type
& PNG_COLOR_MASK_COLOR
))
3097 if (row_info
->color_type
== PNG_COLOR_TYPE_GRAY
)
3099 if (row_info
->bit_depth
== 8)
3101 /* This changes G to RGB */
3102 png_bytep sp
= row
+ (png_size_t
)row_width
- 1;
3103 png_bytep dp
= sp
+ (png_size_t
)row_width
* 2;
3104 for (i
= 0; i
< row_width
; i
++)
3114 /* This changes GG to RRGGBB */
3115 png_bytep sp
= row
+ (png_size_t
)row_width
* 2 - 1;
3116 png_bytep dp
= sp
+ (png_size_t
)row_width
* 4;
3117 for (i
= 0; i
< row_width
; i
++)
3120 *(dp
--) = *(sp
- 1);
3122 *(dp
--) = *(sp
- 1);
3129 else if (row_info
->color_type
== PNG_COLOR_TYPE_GRAY_ALPHA
)
3131 if (row_info
->bit_depth
== 8)
3133 /* This changes GA to RGBA */
3134 png_bytep sp
= row
+ (png_size_t
)row_width
* 2 - 1;
3135 png_bytep dp
= sp
+ (png_size_t
)row_width
* 2;
3136 for (i
= 0; i
< row_width
; i
++)
3147 /* This changes GGAA to RRGGBBAA */
3148 png_bytep sp
= row
+ (png_size_t
)row_width
* 4 - 1;
3149 png_bytep dp
= sp
+ (png_size_t
)row_width
* 4;
3150 for (i
= 0; i
< row_width
; i
++)
3155 *(dp
--) = *(sp
- 1);
3157 *(dp
--) = *(sp
- 1);
3163 row_info
->channels
= (png_byte
)(row_info
->channels
+ 2);
3164 row_info
->color_type
|= PNG_COLOR_MASK_COLOR
;
3165 row_info
->pixel_depth
= (png_byte
)(row_info
->channels
*
3166 row_info
->bit_depth
);
3167 row_info
->rowbytes
= PNG_ROWBYTES(row_info
->pixel_depth
, row_width
);
3172 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
3173 /* Reduce RGB files to grayscale, with or without alpha
3174 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
3175 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
3176 * versions dated 1998 through November 2002 have been archived at
3177 * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
3178 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
3179 * Charles Poynton poynton at poynton.com
3181 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
3183 * which can be expressed with integers as
3185 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
3187 * Poynton's current link (as of January 2003 through July 2011):
3188 * <http://www.poynton.com/notes/colour_and_gamma/>
3189 * has changed the numbers slightly:
3191 * Y = 0.2126*R + 0.7152*G + 0.0722*B
3193 * which can be expressed with integers as
3195 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
3197 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
3198 * end point chromaticities and the D65 white point. Depending on the
3199 * precision used for the D65 white point this produces a variety of different
3200 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
3201 * used (0.3127,0.3290) the Y calculation would be:
3203 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
3205 * While this is correct the rounding results in an overflow for white, because
3206 * the sum of the rounded coefficients is 32769, not 32768. Consequently
3207 * libpng uses, instead, the closest non-overflowing approximation:
3209 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
3211 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
3212 * (including an sRGB chunk) then the chromaticities are used to calculate the
3213 * coefficients. See the chunk handling in pngrutil.c for more information.
3215 * In all cases the calculation is to be done in a linear colorspace. If no
3216 * gamma information is available to correct the encoding of the original RGB
3217 * values this results in an implicit assumption that the original PNG RGB
3218 * values were linear.
3220 * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
3221 * the API takes just red and green coefficients the blue coefficient is
3222 * calculated to make the sum 32768. This will result in different rounding
3223 * to that used above.
3226 png_do_rgb_to_gray(png_structp png_ptr
, png_row_infop row_info
, png_bytep row
)
3231 png_debug(1, "in png_do_rgb_to_gray");
3233 if (!(row_info
->color_type
& PNG_COLOR_MASK_PALETTE
) &&
3234 (row_info
->color_type
& PNG_COLOR_MASK_COLOR
))
3236 PNG_CONST png_uint_32 rc
= png_ptr
->rgb_to_gray_red_coeff
;
3237 PNG_CONST png_uint_32 gc
= png_ptr
->rgb_to_gray_green_coeff
;
3238 PNG_CONST png_uint_32 bc
= 32768 - rc
- gc
;
3239 PNG_CONST png_uint_32 row_width
= row_info
->width
;
3240 PNG_CONST
int have_alpha
=
3241 (row_info
->color_type
& PNG_COLOR_MASK_ALPHA
) != 0;
3243 if (row_info
->bit_depth
== 8)
3245 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
3246 /* Notice that gamma to/from 1 are not necessarily inverses (if
3247 * there is an overall gamma correction). Prior to 1.5.5 this code
3248 * checked the linearized values for equality; this doesn't match
3249 * the documentation, the original values must be checked.
3251 if (png_ptr
->gamma_from_1
!= NULL
&& png_ptr
->gamma_to_1
!= NULL
)
3257 for (i
= 0; i
< row_width
; i
++)
3259 png_byte red
= *(sp
++);
3260 png_byte green
= *(sp
++);
3261 png_byte blue
= *(sp
++);
3263 if (red
!= green
|| red
!= blue
)
3265 red
= png_ptr
->gamma_to_1
[red
];
3266 green
= png_ptr
->gamma_to_1
[green
];
3267 blue
= png_ptr
->gamma_to_1
[blue
];
3270 *(dp
++) = png_ptr
->gamma_from_1
[
3271 (rc
*red
+ gc
*green
+ bc
*blue
+ 16384)>>15];
3276 /* If there is no overall correction the table will not be
3279 if (png_ptr
->gamma_table
!= NULL
)
3280 red
= png_ptr
->gamma_table
[red
];
3296 for (i
= 0; i
< row_width
; i
++)
3298 png_byte red
= *(sp
++);
3299 png_byte green
= *(sp
++);
3300 png_byte blue
= *(sp
++);
3302 if (red
!= green
|| red
!= blue
)
3305 /*NOTE: this is the historical approach which simply
3306 * truncates the results.
3308 *(dp
++) = (png_byte
)((rc
*red
+ gc
*green
+ bc
*blue
)>>15);
3320 else /* RGB bit_depth == 16 */
3322 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
3323 if (png_ptr
->gamma_16_to_1
!= NULL
&& png_ptr
->gamma_16_from_1
!= NULL
)
3329 for (i
= 0; i
< row_width
; i
++)
3331 png_uint_16 red
, green
, blue
, w
;
3333 red
= (png_uint_16
)(((*(sp
))<<8) | *(sp
+ 1)); sp
+= 2;
3334 green
= (png_uint_16
)(((*(sp
))<<8) | *(sp
+ 1)); sp
+= 2;
3335 blue
= (png_uint_16
)(((*(sp
))<<8) | *(sp
+ 1)); sp
+= 2;
3337 if (red
== green
&& red
== blue
)
3339 if (png_ptr
->gamma_16_table
!= NULL
)
3340 w
= png_ptr
->gamma_16_table
[(red
&0xff)
3341 >> png_ptr
->gamma_shift
][red
>>8];
3349 png_uint_16 red_1
= png_ptr
->gamma_16_to_1
[(red
&0xff)
3350 >> png_ptr
->gamma_shift
][red
>>8];
3351 png_uint_16 green_1
=
3352 png_ptr
->gamma_16_to_1
[(green
&0xff) >>
3353 png_ptr
->gamma_shift
][green
>>8];
3354 png_uint_16 blue_1
= png_ptr
->gamma_16_to_1
[(blue
&0xff)
3355 >> png_ptr
->gamma_shift
][blue
>>8];
3356 png_uint_16 gray16
= (png_uint_16
)((rc
*red_1
+ gc
*green_1
3357 + bc
*blue_1
+ 16384)>>15);
3358 w
= png_ptr
->gamma_16_from_1
[(gray16
&0xff) >>
3359 png_ptr
->gamma_shift
][gray16
>> 8];
3363 *(dp
++) = (png_byte
)((w
>>8) & 0xff);
3364 *(dp
++) = (png_byte
)(w
& 0xff);
3380 for (i
= 0; i
< row_width
; i
++)
3382 png_uint_16 red
, green
, blue
, gray16
;
3384 red
= (png_uint_16
)(((*(sp
))<<8) | *(sp
+ 1)); sp
+= 2;
3385 green
= (png_uint_16
)(((*(sp
))<<8) | *(sp
+ 1)); sp
+= 2;
3386 blue
= (png_uint_16
)(((*(sp
))<<8) | *(sp
+ 1)); sp
+= 2;
3388 if (red
!= green
|| red
!= blue
)
3391 /* From 1.5.5 in the 16 bit case do the accurate conversion even
3392 * in the 'fast' case - this is because this is where the code
3393 * ends up when handling linear 16 bit data.
3395 gray16
= (png_uint_16
)((rc
*red
+ gc
*green
+ bc
*blue
+ 16384) >>
3397 *(dp
++) = (png_byte
)((gray16
>>8) & 0xff);
3398 *(dp
++) = (png_byte
)(gray16
& 0xff);
3409 row_info
->channels
= (png_byte
)(row_info
->channels
- 2);
3410 row_info
->color_type
= (png_byte
)(row_info
->color_type
&
3411 ~PNG_COLOR_MASK_COLOR
);
3412 row_info
->pixel_depth
= (png_byte
)(row_info
->channels
*
3413 row_info
->bit_depth
);
3414 row_info
->rowbytes
= PNG_ROWBYTES(row_info
->pixel_depth
, row_width
);
3419 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
3421 #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
3422 /* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
3423 * large of png_color. This lets grayscale images be treated as
3424 * paletted. Most useful for gamma correction and simplification
3425 * of code. This API is not used internally.
3428 png_build_grayscale_palette(int bit_depth
, png_colorp palette
)
3435 png_debug(1, "in png_do_build_grayscale_palette");
3437 if (palette
== NULL
)
3468 for (i
= 0, v
= 0; i
< num_palette
; i
++, v
+= color_inc
)
3470 palette
[i
].red
= (png_byte
)v
;
3471 palette
[i
].green
= (png_byte
)v
;
3472 palette
[i
].blue
= (png_byte
)v
;
3478 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
3479 #if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
3480 (defined PNG_READ_ALPHA_MODE_SUPPORTED)
3481 /* Replace any alpha or transparency with the supplied background color.
3482 * "background" is already in the screen gamma, while "background_1" is
3483 * at a gamma of 1.0. Paletted files have already been taken care of.
3486 png_do_compose(png_row_infop row_info
, png_bytep row
, png_structp png_ptr
)
3488 #ifdef PNG_READ_GAMMA_SUPPORTED
3489 png_const_bytep gamma_table
= png_ptr
->gamma_table
;
3490 png_const_bytep gamma_from_1
= png_ptr
->gamma_from_1
;
3491 png_const_bytep gamma_to_1
= png_ptr
->gamma_to_1
;
3492 png_const_uint_16pp gamma_16
= png_ptr
->gamma_16_table
;
3493 png_const_uint_16pp gamma_16_from_1
= png_ptr
->gamma_16_from_1
;
3494 png_const_uint_16pp gamma_16_to_1
= png_ptr
->gamma_16_to_1
;
3495 int gamma_shift
= png_ptr
->gamma_shift
;
3500 png_uint_32 row_width
= row_info
->width
;
3501 int optimize
= (png_ptr
->flags
& PNG_FLAG_OPTIMIZE_ALPHA
) != 0;
3504 png_debug(1, "in png_do_compose");
3507 switch (row_info
->color_type
)
3509 case PNG_COLOR_TYPE_GRAY
:
3511 switch (row_info
->bit_depth
)
3517 for (i
= 0; i
< row_width
; i
++)
3519 if ((png_uint_16
)((*sp
>> shift
) & 0x01)
3520 == png_ptr
->trans_color
.gray
)
3522 *sp
&= (png_byte
)((0x7f7f >> (7 - shift
)) & 0xff);
3523 *sp
|= (png_byte
)(png_ptr
->background
.gray
<< shift
);
3540 #ifdef PNG_READ_GAMMA_SUPPORTED
3541 if (gamma_table
!= NULL
)
3545 for (i
= 0; i
< row_width
; i
++)
3547 if ((png_uint_16
)((*sp
>> shift
) & 0x03)
3548 == png_ptr
->trans_color
.gray
)
3550 *sp
&= (png_byte
)((0x3f3f >> (6 - shift
)) & 0xff);
3551 *sp
|= (png_byte
)(png_ptr
->background
.gray
<< shift
);
3556 png_byte p
= (png_byte
)((*sp
>> shift
) & 0x03);
3557 png_byte g
= (png_byte
)((gamma_table
[p
| (p
<< 2) |
3558 (p
<< 4) | (p
<< 6)] >> 6) & 0x03);
3559 *sp
&= (png_byte
)((0x3f3f >> (6 - shift
)) & 0xff);
3560 *sp
|= (png_byte
)(g
<< shift
);
3579 for (i
= 0; i
< row_width
; i
++)
3581 if ((png_uint_16
)((*sp
>> shift
) & 0x03)
3582 == png_ptr
->trans_color
.gray
)
3584 *sp
&= (png_byte
)((0x3f3f >> (6 - shift
)) & 0xff);
3585 *sp
|= (png_byte
)(png_ptr
->background
.gray
<< shift
);
3603 #ifdef PNG_READ_GAMMA_SUPPORTED
3604 if (gamma_table
!= NULL
)
3608 for (i
= 0; i
< row_width
; i
++)
3610 if ((png_uint_16
)((*sp
>> shift
) & 0x0f)
3611 == png_ptr
->trans_color
.gray
)
3613 *sp
&= (png_byte
)((0xf0f >> (4 - shift
)) & 0xff);
3614 *sp
|= (png_byte
)(png_ptr
->background
.gray
<< shift
);
3619 png_byte p
= (png_byte
)((*sp
>> shift
) & 0x0f);
3620 png_byte g
= (png_byte
)((gamma_table
[p
|
3621 (p
<< 4)] >> 4) & 0x0f);
3622 *sp
&= (png_byte
)((0xf0f >> (4 - shift
)) & 0xff);
3623 *sp
|= (png_byte
)(g
<< shift
);
3642 for (i
= 0; i
< row_width
; i
++)
3644 if ((png_uint_16
)((*sp
>> shift
) & 0x0f)
3645 == png_ptr
->trans_color
.gray
)
3647 *sp
&= (png_byte
)((0xf0f >> (4 - shift
)) & 0xff);
3648 *sp
|= (png_byte
)(png_ptr
->background
.gray
<< shift
);
3666 #ifdef PNG_READ_GAMMA_SUPPORTED
3667 if (gamma_table
!= NULL
)
3670 for (i
= 0; i
< row_width
; i
++, sp
++)
3672 if (*sp
== png_ptr
->trans_color
.gray
)
3673 *sp
= (png_byte
)png_ptr
->background
.gray
;
3676 *sp
= gamma_table
[*sp
];
3683 for (i
= 0; i
< row_width
; i
++, sp
++)
3685 if (*sp
== png_ptr
->trans_color
.gray
)
3686 *sp
= (png_byte
)png_ptr
->background
.gray
;
3694 #ifdef PNG_READ_GAMMA_SUPPORTED
3695 if (gamma_16
!= NULL
)
3698 for (i
= 0; i
< row_width
; i
++, sp
+= 2)
3702 v
= (png_uint_16
)(((*sp
) << 8) + *(sp
+ 1));
3704 if (v
== png_ptr
->trans_color
.gray
)
3706 /* Background is already in screen gamma */
3707 *sp
= (png_byte
)((png_ptr
->background
.gray
>> 8) & 0xff);
3708 *(sp
+ 1) = (png_byte
)(png_ptr
->background
.gray
& 0xff);
3713 v
= gamma_16
[*(sp
+ 1) >> gamma_shift
][*sp
];
3714 *sp
= (png_byte
)((v
>> 8) & 0xff);
3715 *(sp
+ 1) = (png_byte
)(v
& 0xff);
3723 for (i
= 0; i
< row_width
; i
++, sp
+= 2)
3727 v
= (png_uint_16
)(((*sp
) << 8) + *(sp
+ 1));
3729 if (v
== png_ptr
->trans_color
.gray
)
3731 *sp
= (png_byte
)((png_ptr
->background
.gray
>> 8) & 0xff);
3732 *(sp
+ 1) = (png_byte
)(png_ptr
->background
.gray
& 0xff);
3745 case PNG_COLOR_TYPE_RGB
:
3747 if (row_info
->bit_depth
== 8)
3749 #ifdef PNG_READ_GAMMA_SUPPORTED
3750 if (gamma_table
!= NULL
)
3753 for (i
= 0; i
< row_width
; i
++, sp
+= 3)
3755 if (*sp
== png_ptr
->trans_color
.red
&&
3756 *(sp
+ 1) == png_ptr
->trans_color
.green
&&
3757 *(sp
+ 2) == png_ptr
->trans_color
.blue
)
3759 *sp
= (png_byte
)png_ptr
->background
.red
;
3760 *(sp
+ 1) = (png_byte
)png_ptr
->background
.green
;
3761 *(sp
+ 2) = (png_byte
)png_ptr
->background
.blue
;
3766 *sp
= gamma_table
[*sp
];
3767 *(sp
+ 1) = gamma_table
[*(sp
+ 1)];
3768 *(sp
+ 2) = gamma_table
[*(sp
+ 2)];
3776 for (i
= 0; i
< row_width
; i
++, sp
+= 3)
3778 if (*sp
== png_ptr
->trans_color
.red
&&
3779 *(sp
+ 1) == png_ptr
->trans_color
.green
&&
3780 *(sp
+ 2) == png_ptr
->trans_color
.blue
)
3782 *sp
= (png_byte
)png_ptr
->background
.red
;
3783 *(sp
+ 1) = (png_byte
)png_ptr
->background
.green
;
3784 *(sp
+ 2) = (png_byte
)png_ptr
->background
.blue
;
3789 else /* if (row_info->bit_depth == 16) */
3791 #ifdef PNG_READ_GAMMA_SUPPORTED
3792 if (gamma_16
!= NULL
)
3795 for (i
= 0; i
< row_width
; i
++, sp
+= 6)
3797 png_uint_16 r
= (png_uint_16
)(((*sp
) << 8) + *(sp
+ 1));
3799 png_uint_16 g
= (png_uint_16
)(((*(sp
+ 2)) << 8)
3802 png_uint_16 b
= (png_uint_16
)(((*(sp
+ 4)) << 8)
3805 if (r
== png_ptr
->trans_color
.red
&&
3806 g
== png_ptr
->trans_color
.green
&&
3807 b
== png_ptr
->trans_color
.blue
)
3809 /* Background is already in screen gamma */
3810 *sp
= (png_byte
)((png_ptr
->background
.red
>> 8) & 0xff);
3811 *(sp
+ 1) = (png_byte
)(png_ptr
->background
.red
& 0xff);
3812 *(sp
+ 2) = (png_byte
)((png_ptr
->background
.green
>> 8) & 0xff);
3813 *(sp
+ 3) = (png_byte
)(png_ptr
->background
.green
& 0xff);
3814 *(sp
+ 4) = (png_byte
)((png_ptr
->background
.blue
>> 8) & 0xff);
3815 *(sp
+ 5) = (png_byte
)(png_ptr
->background
.blue
& 0xff);
3820 png_uint_16 v
= gamma_16
[*(sp
+ 1) >> gamma_shift
][*sp
];
3821 *sp
= (png_byte
)((v
>> 8) & 0xff);
3822 *(sp
+ 1) = (png_byte
)(v
& 0xff);
3824 v
= gamma_16
[*(sp
+ 3) >> gamma_shift
][*(sp
+ 2)];
3825 *(sp
+ 2) = (png_byte
)((v
>> 8) & 0xff);
3826 *(sp
+ 3) = (png_byte
)(v
& 0xff);
3828 v
= gamma_16
[*(sp
+ 5) >> gamma_shift
][*(sp
+ 4)];
3829 *(sp
+ 4) = (png_byte
)((v
>> 8) & 0xff);
3830 *(sp
+ 5) = (png_byte
)(v
& 0xff);
3839 for (i
= 0; i
< row_width
; i
++, sp
+= 6)
3841 png_uint_16 r
= (png_uint_16
)(((*sp
) << 8) + *(sp
+ 1));
3843 png_uint_16 g
= (png_uint_16
)(((*(sp
+ 2)) << 8)
3846 png_uint_16 b
= (png_uint_16
)(((*(sp
+ 4)) << 8)
3849 if (r
== png_ptr
->trans_color
.red
&&
3850 g
== png_ptr
->trans_color
.green
&&
3851 b
== png_ptr
->trans_color
.blue
)
3853 *sp
= (png_byte
)((png_ptr
->background
.red
>> 8) & 0xff);
3854 *(sp
+ 1) = (png_byte
)(png_ptr
->background
.red
& 0xff);
3855 *(sp
+ 2) = (png_byte
)((png_ptr
->background
.green
>> 8) & 0xff);
3856 *(sp
+ 3) = (png_byte
)(png_ptr
->background
.green
& 0xff);
3857 *(sp
+ 4) = (png_byte
)((png_ptr
->background
.blue
>> 8) & 0xff);
3858 *(sp
+ 5) = (png_byte
)(png_ptr
->background
.blue
& 0xff);
3866 case PNG_COLOR_TYPE_GRAY_ALPHA
:
3868 if (row_info
->bit_depth
== 8)
3870 #ifdef PNG_READ_GAMMA_SUPPORTED
3871 if (gamma_to_1
!= NULL
&& gamma_from_1
!= NULL
&&
3872 gamma_table
!= NULL
)
3875 for (i
= 0; i
< row_width
; i
++, sp
+= 2)
3877 png_uint_16 a
= *(sp
+ 1);
3880 *sp
= gamma_table
[*sp
];
3884 /* Background is already in screen gamma */
3885 *sp
= (png_byte
)png_ptr
->background
.gray
;
3892 v
= gamma_to_1
[*sp
];
3893 png_composite(w
, v
, a
, png_ptr
->background_1
.gray
);
3895 w
= gamma_from_1
[w
];
3904 for (i
= 0; i
< row_width
; i
++, sp
+= 2)
3906 png_byte a
= *(sp
+ 1);
3909 *sp
= (png_byte
)png_ptr
->background
.gray
;
3912 png_composite(*sp
, *sp
, a
, png_ptr
->background_1
.gray
);
3916 else /* if (png_ptr->bit_depth == 16) */
3918 #ifdef PNG_READ_GAMMA_SUPPORTED
3919 if (gamma_16
!= NULL
&& gamma_16_from_1
!= NULL
&&
3920 gamma_16_to_1
!= NULL
)
3923 for (i
= 0; i
< row_width
; i
++, sp
+= 4)
3925 png_uint_16 a
= (png_uint_16
)(((*(sp
+ 2)) << 8)
3928 if (a
== (png_uint_16
)0xffff)
3932 v
= gamma_16
[*(sp
+ 1) >> gamma_shift
][*sp
];
3933 *sp
= (png_byte
)((v
>> 8) & 0xff);
3934 *(sp
+ 1) = (png_byte
)(v
& 0xff);
3939 /* Background is already in screen gamma */
3940 *sp
= (png_byte
)((png_ptr
->background
.gray
>> 8) & 0xff);
3941 *(sp
+ 1) = (png_byte
)(png_ptr
->background
.gray
& 0xff);
3946 png_uint_16 g
, v
, w
;
3948 g
= gamma_16_to_1
[*(sp
+ 1) >> gamma_shift
][*sp
];
3949 png_composite_16(v
, g
, a
, png_ptr
->background_1
.gray
);
3953 w
= gamma_16_from_1
[(v
&0xff) >> gamma_shift
][v
>> 8];
3954 *sp
= (png_byte
)((w
>> 8) & 0xff);
3955 *(sp
+ 1) = (png_byte
)(w
& 0xff);
3963 for (i
= 0; i
< row_width
; i
++, sp
+= 4)
3965 png_uint_16 a
= (png_uint_16
)(((*(sp
+ 2)) << 8)
3970 *sp
= (png_byte
)((png_ptr
->background
.gray
>> 8) & 0xff);
3971 *(sp
+ 1) = (png_byte
)(png_ptr
->background
.gray
& 0xff);
3974 else if (a
< 0xffff)
3978 g
= (png_uint_16
)(((*sp
) << 8) + *(sp
+ 1));
3979 png_composite_16(v
, g
, a
, png_ptr
->background_1
.gray
);
3980 *sp
= (png_byte
)((v
>> 8) & 0xff);
3981 *(sp
+ 1) = (png_byte
)(v
& 0xff);
3989 case PNG_COLOR_TYPE_RGB_ALPHA
:
3991 if (row_info
->bit_depth
== 8)
3993 #ifdef PNG_READ_GAMMA_SUPPORTED
3994 if (gamma_to_1
!= NULL
&& gamma_from_1
!= NULL
&&
3995 gamma_table
!= NULL
)
3998 for (i
= 0; i
< row_width
; i
++, sp
+= 4)
4000 png_byte a
= *(sp
+ 3);
4004 *sp
= gamma_table
[*sp
];
4005 *(sp
+ 1) = gamma_table
[*(sp
+ 1)];
4006 *(sp
+ 2) = gamma_table
[*(sp
+ 2)];
4011 /* Background is already in screen gamma */
4012 *sp
= (png_byte
)png_ptr
->background
.red
;
4013 *(sp
+ 1) = (png_byte
)png_ptr
->background
.green
;
4014 *(sp
+ 2) = (png_byte
)png_ptr
->background
.blue
;
4021 v
= gamma_to_1
[*sp
];
4022 png_composite(w
, v
, a
, png_ptr
->background_1
.red
);
4023 if (!optimize
) w
= gamma_from_1
[w
];
4026 v
= gamma_to_1
[*(sp
+ 1)];
4027 png_composite(w
, v
, a
, png_ptr
->background_1
.green
);
4028 if (!optimize
) w
= gamma_from_1
[w
];
4031 v
= gamma_to_1
[*(sp
+ 2)];
4032 png_composite(w
, v
, a
, png_ptr
->background_1
.blue
);
4033 if (!optimize
) w
= gamma_from_1
[w
];
4042 for (i
= 0; i
< row_width
; i
++, sp
+= 4)
4044 png_byte a
= *(sp
+ 3);
4048 *sp
= (png_byte
)png_ptr
->background
.red
;
4049 *(sp
+ 1) = (png_byte
)png_ptr
->background
.green
;
4050 *(sp
+ 2) = (png_byte
)png_ptr
->background
.blue
;
4055 png_composite(*sp
, *sp
, a
, png_ptr
->background
.red
);
4057 png_composite(*(sp
+ 1), *(sp
+ 1), a
,
4058 png_ptr
->background
.green
);
4060 png_composite(*(sp
+ 2), *(sp
+ 2), a
,
4061 png_ptr
->background
.blue
);
4066 else /* if (row_info->bit_depth == 16) */
4068 #ifdef PNG_READ_GAMMA_SUPPORTED
4069 if (gamma_16
!= NULL
&& gamma_16_from_1
!= NULL
&&
4070 gamma_16_to_1
!= NULL
)
4073 for (i
= 0; i
< row_width
; i
++, sp
+= 8)
4075 png_uint_16 a
= (png_uint_16
)(((png_uint_16
)(*(sp
+ 6))
4076 << 8) + (png_uint_16
)(*(sp
+ 7)));
4078 if (a
== (png_uint_16
)0xffff)
4082 v
= gamma_16
[*(sp
+ 1) >> gamma_shift
][*sp
];
4083 *sp
= (png_byte
)((v
>> 8) & 0xff);
4084 *(sp
+ 1) = (png_byte
)(v
& 0xff);
4086 v
= gamma_16
[*(sp
+ 3) >> gamma_shift
][*(sp
+ 2)];
4087 *(sp
+ 2) = (png_byte
)((v
>> 8) & 0xff);
4088 *(sp
+ 3) = (png_byte
)(v
& 0xff);
4090 v
= gamma_16
[*(sp
+ 5) >> gamma_shift
][*(sp
+ 4)];
4091 *(sp
+ 4) = (png_byte
)((v
>> 8) & 0xff);
4092 *(sp
+ 5) = (png_byte
)(v
& 0xff);
4097 /* Background is already in screen gamma */
4098 *sp
= (png_byte
)((png_ptr
->background
.red
>> 8) & 0xff);
4099 *(sp
+ 1) = (png_byte
)(png_ptr
->background
.red
& 0xff);
4100 *(sp
+ 2) = (png_byte
)((png_ptr
->background
.green
>> 8) & 0xff);
4101 *(sp
+ 3) = (png_byte
)(png_ptr
->background
.green
& 0xff);
4102 *(sp
+ 4) = (png_byte
)((png_ptr
->background
.blue
>> 8) & 0xff);
4103 *(sp
+ 5) = (png_byte
)(png_ptr
->background
.blue
& 0xff);
4110 v
= gamma_16_to_1
[*(sp
+ 1) >> gamma_shift
][*sp
];
4111 png_composite_16(w
, v
, a
, png_ptr
->background_1
.red
);
4113 w
= gamma_16_from_1
[((w
&0xff) >> gamma_shift
)][w
>> 8];
4114 *sp
= (png_byte
)((w
>> 8) & 0xff);
4115 *(sp
+ 1) = (png_byte
)(w
& 0xff);
4117 v
= gamma_16_to_1
[*(sp
+ 3) >> gamma_shift
][*(sp
+ 2)];
4118 png_composite_16(w
, v
, a
, png_ptr
->background_1
.green
);
4120 w
= gamma_16_from_1
[((w
&0xff) >> gamma_shift
)][w
>> 8];
4122 *(sp
+ 2) = (png_byte
)((w
>> 8) & 0xff);
4123 *(sp
+ 3) = (png_byte
)(w
& 0xff);
4125 v
= gamma_16_to_1
[*(sp
+ 5) >> gamma_shift
][*(sp
+ 4)];
4126 png_composite_16(w
, v
, a
, png_ptr
->background_1
.blue
);
4128 w
= gamma_16_from_1
[((w
&0xff) >> gamma_shift
)][w
>> 8];
4130 *(sp
+ 4) = (png_byte
)((w
>> 8) & 0xff);
4131 *(sp
+ 5) = (png_byte
)(w
& 0xff);
4140 for (i
= 0; i
< row_width
; i
++, sp
+= 8)
4142 png_uint_16 a
= (png_uint_16
)(((png_uint_16
)(*(sp
+ 6))
4143 << 8) + (png_uint_16
)(*(sp
+ 7)));
4147 *sp
= (png_byte
)((png_ptr
->background
.red
>> 8) & 0xff);
4148 *(sp
+ 1) = (png_byte
)(png_ptr
->background
.red
& 0xff);
4149 *(sp
+ 2) = (png_byte
)((png_ptr
->background
.green
>> 8) & 0xff);
4150 *(sp
+ 3) = (png_byte
)(png_ptr
->background
.green
& 0xff);
4151 *(sp
+ 4) = (png_byte
)((png_ptr
->background
.blue
>> 8) & 0xff);
4152 *(sp
+ 5) = (png_byte
)(png_ptr
->background
.blue
& 0xff);
4155 else if (a
< 0xffff)
4159 png_uint_16 r
= (png_uint_16
)(((*sp
) << 8) + *(sp
+ 1));
4160 png_uint_16 g
= (png_uint_16
)(((*(sp
+ 2)) << 8)
4162 png_uint_16 b
= (png_uint_16
)(((*(sp
+ 4)) << 8)
4165 png_composite_16(v
, r
, a
, png_ptr
->background
.red
);
4166 *sp
= (png_byte
)((v
>> 8) & 0xff);
4167 *(sp
+ 1) = (png_byte
)(v
& 0xff);
4169 png_composite_16(v
, g
, a
, png_ptr
->background
.green
);
4170 *(sp
+ 2) = (png_byte
)((v
>> 8) & 0xff);
4171 *(sp
+ 3) = (png_byte
)(v
& 0xff);
4173 png_composite_16(v
, b
, a
, png_ptr
->background
.blue
);
4174 *(sp
+ 4) = (png_byte
)((v
>> 8) & 0xff);
4175 *(sp
+ 5) = (png_byte
)(v
& 0xff);
4188 #endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_READ_ALPHA_MODE_SUPPORTED */
4190 #ifdef PNG_READ_GAMMA_SUPPORTED
4191 /* Gamma correct the image, avoiding the alpha channel. Make sure
4192 * you do this after you deal with the transparency issue on grayscale
4193 * or RGB images. If your bit depth is 8, use gamma_table, if it
4194 * is 16, use gamma_16_table and gamma_shift. Build these with
4195 * build_gamma_table().
4198 png_do_gamma(png_row_infop row_info
, png_bytep row
, png_structp png_ptr
)
4200 png_const_bytep gamma_table
= png_ptr
->gamma_table
;
4201 png_const_uint_16pp gamma_16_table
= png_ptr
->gamma_16_table
;
4202 int gamma_shift
= png_ptr
->gamma_shift
;
4206 png_uint_32 row_width
=row_info
->width
;
4208 png_debug(1, "in png_do_gamma");
4210 if (((row_info
->bit_depth
<= 8 && gamma_table
!= NULL
) ||
4211 (row_info
->bit_depth
== 16 && gamma_16_table
!= NULL
)))
4213 switch (row_info
->color_type
)
4215 case PNG_COLOR_TYPE_RGB
:
4217 if (row_info
->bit_depth
== 8)
4220 for (i
= 0; i
< row_width
; i
++)
4222 *sp
= gamma_table
[*sp
];
4224 *sp
= gamma_table
[*sp
];
4226 *sp
= gamma_table
[*sp
];
4231 else /* if (row_info->bit_depth == 16) */
4234 for (i
= 0; i
< row_width
; i
++)
4238 v
= gamma_16_table
[*(sp
+ 1) >> gamma_shift
][*sp
];
4239 *sp
= (png_byte
)((v
>> 8) & 0xff);
4240 *(sp
+ 1) = (png_byte
)(v
& 0xff);
4243 v
= gamma_16_table
[*(sp
+ 1) >> gamma_shift
][*sp
];
4244 *sp
= (png_byte
)((v
>> 8) & 0xff);
4245 *(sp
+ 1) = (png_byte
)(v
& 0xff);
4248 v
= gamma_16_table
[*(sp
+ 1) >> gamma_shift
][*sp
];
4249 *sp
= (png_byte
)((v
>> 8) & 0xff);
4250 *(sp
+ 1) = (png_byte
)(v
& 0xff);
4257 case PNG_COLOR_TYPE_RGB_ALPHA
:
4259 if (row_info
->bit_depth
== 8)
4262 for (i
= 0; i
< row_width
; i
++)
4264 *sp
= gamma_table
[*sp
];
4267 *sp
= gamma_table
[*sp
];
4270 *sp
= gamma_table
[*sp
];
4277 else /* if (row_info->bit_depth == 16) */
4280 for (i
= 0; i
< row_width
; i
++)
4282 png_uint_16 v
= gamma_16_table
[*(sp
+ 1) >> gamma_shift
][*sp
];
4283 *sp
= (png_byte
)((v
>> 8) & 0xff);
4284 *(sp
+ 1) = (png_byte
)(v
& 0xff);
4287 v
= gamma_16_table
[*(sp
+ 1) >> gamma_shift
][*sp
];
4288 *sp
= (png_byte
)((v
>> 8) & 0xff);
4289 *(sp
+ 1) = (png_byte
)(v
& 0xff);
4292 v
= gamma_16_table
[*(sp
+ 1) >> gamma_shift
][*sp
];
4293 *sp
= (png_byte
)((v
>> 8) & 0xff);
4294 *(sp
+ 1) = (png_byte
)(v
& 0xff);
4301 case PNG_COLOR_TYPE_GRAY_ALPHA
:
4303 if (row_info
->bit_depth
== 8)
4306 for (i
= 0; i
< row_width
; i
++)
4308 *sp
= gamma_table
[*sp
];
4313 else /* if (row_info->bit_depth == 16) */
4316 for (i
= 0; i
< row_width
; i
++)
4318 png_uint_16 v
= gamma_16_table
[*(sp
+ 1) >> gamma_shift
][*sp
];
4319 *sp
= (png_byte
)((v
>> 8) & 0xff);
4320 *(sp
+ 1) = (png_byte
)(v
& 0xff);
4327 case PNG_COLOR_TYPE_GRAY
:
4329 if (row_info
->bit_depth
== 2)
4332 for (i
= 0; i
< row_width
; i
+= 4)
4340 ((((int)gamma_table
[a
|(a
>>2)|(a
>>4)|(a
>>6)]) ) & 0xc0)|
4341 ((((int)gamma_table
[(b
<<2)|b
|(b
>>2)|(b
>>4)])>>2) & 0x30)|
4342 ((((int)gamma_table
[(c
<<4)|(c
<<2)|c
|(c
>>2)])>>4) & 0x0c)|
4343 ((((int)gamma_table
[(d
<<6)|(d
<<4)|(d
<<2)|d
])>>6) ));
4348 if (row_info
->bit_depth
== 4)
4351 for (i
= 0; i
< row_width
; i
+= 2)
4353 int msb
= *sp
& 0xf0;
4354 int lsb
= *sp
& 0x0f;
4356 *sp
= (png_byte
)((((int)gamma_table
[msb
| (msb
>> 4)]) & 0xf0)
4357 | (((int)gamma_table
[(lsb
<< 4) | lsb
]) >> 4));
4362 else if (row_info
->bit_depth
== 8)
4365 for (i
= 0; i
< row_width
; i
++)
4367 *sp
= gamma_table
[*sp
];
4372 else if (row_info
->bit_depth
== 16)
4375 for (i
= 0; i
< row_width
; i
++)
4377 png_uint_16 v
= gamma_16_table
[*(sp
+ 1) >> gamma_shift
][*sp
];
4378 *sp
= (png_byte
)((v
>> 8) & 0xff);
4379 *(sp
+ 1) = (png_byte
)(v
& 0xff);
4393 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4394 /* Encode the alpha channel to the output gamma (the input channel is always
4395 * linear.) Called only with color types that have an alpha channel. Needs the
4399 png_do_encode_alpha(png_row_infop row_info
, png_bytep row
, png_structp png_ptr
)
4401 png_uint_32 row_width
= row_info
->width
;
4403 png_debug(1, "in png_do_encode_alpha");
4405 if (row_info
->color_type
& PNG_COLOR_MASK_ALPHA
)
4407 if (row_info
->bit_depth
== 8)
4409 PNG_CONST png_bytep table
= png_ptr
->gamma_from_1
;
4413 PNG_CONST
int step
=
4414 (row_info
->color_type
& PNG_COLOR_MASK_COLOR
) ? 4 : 2;
4416 /* The alpha channel is the last component: */
4419 for (; row_width
> 0; --row_width
, row
+= step
)
4426 else if (row_info
->bit_depth
== 16)
4428 PNG_CONST png_uint_16pp table
= png_ptr
->gamma_16_from_1
;
4429 PNG_CONST
int gamma_shift
= png_ptr
->gamma_shift
;
4433 PNG_CONST
int step
=
4434 (row_info
->color_type
& PNG_COLOR_MASK_COLOR
) ? 8 : 4;
4436 /* The alpha channel is the last component: */
4439 for (; row_width
> 0; --row_width
, row
+= step
)
4443 v
= table
[*(row
+ 1) >> gamma_shift
][*row
];
4444 *row
= (png_byte
)((v
>> 8) & 0xff);
4445 *(row
+ 1) = (png_byte
)(v
& 0xff);
4453 /* Only get to here if called with a weird row_info; no harm has been done,
4454 * so just issue a warning.
4456 png_warning(png_ptr
, "png_do_encode_alpha: unexpected call");
4460 #ifdef PNG_READ_EXPAND_SUPPORTED
4461 /* Expands a palette row to an RGB or RGBA row depending
4462 * upon whether you supply trans and num_trans.
4465 png_do_expand_palette(png_row_infop row_info
, png_bytep row
,
4466 png_const_colorp palette
, png_const_bytep trans_alpha
, int num_trans
)
4471 png_uint_32 row_width
=row_info
->width
;
4473 png_debug(1, "in png_do_expand_palette");
4475 if (row_info
->color_type
== PNG_COLOR_TYPE_PALETTE
)
4477 if (row_info
->bit_depth
< 8)
4479 switch (row_info
->bit_depth
)
4483 sp
= row
+ (png_size_t
)((row_width
- 1) >> 3);
4484 dp
= row
+ (png_size_t
)row_width
- 1;
4485 shift
= 7 - (int)((row_width
+ 7) & 0x07);
4486 for (i
= 0; i
< row_width
; i
++)
4488 if ((*sp
>> shift
) & 0x01)
4510 sp
= row
+ (png_size_t
)((row_width
- 1) >> 2);
4511 dp
= row
+ (png_size_t
)row_width
- 1;
4512 shift
= (int)((3 - ((row_width
+ 3) & 0x03)) << 1);
4513 for (i
= 0; i
< row_width
; i
++)
4515 value
= (*sp
>> shift
) & 0x03;
4516 *dp
= (png_byte
)value
;
4533 sp
= row
+ (png_size_t
)((row_width
- 1) >> 1);
4534 dp
= row
+ (png_size_t
)row_width
- 1;
4535 shift
= (int)((row_width
& 0x01) << 2);
4536 for (i
= 0; i
< row_width
; i
++)
4538 value
= (*sp
>> shift
) & 0x0f;
4539 *dp
= (png_byte
)value
;
4557 row_info
->bit_depth
= 8;
4558 row_info
->pixel_depth
= 8;
4559 row_info
->rowbytes
= row_width
;
4562 if (row_info
->bit_depth
== 8)
4567 sp
= row
+ (png_size_t
)row_width
- 1;
4568 dp
= row
+ (png_size_t
)(row_width
<< 2) - 1;
4570 for (i
= 0; i
< row_width
; i
++)
4572 if ((int)(*sp
) >= num_trans
)
4576 *dp
-- = trans_alpha
[*sp
];
4578 *dp
-- = palette
[*sp
].blue
;
4579 *dp
-- = palette
[*sp
].green
;
4580 *dp
-- = palette
[*sp
].red
;
4583 row_info
->bit_depth
= 8;
4584 row_info
->pixel_depth
= 32;
4585 row_info
->rowbytes
= row_width
* 4;
4586 row_info
->color_type
= 6;
4587 row_info
->channels
= 4;
4592 sp
= row
+ (png_size_t
)row_width
- 1;
4593 dp
= row
+ (png_size_t
)(row_width
* 3) - 1;
4595 for (i
= 0; i
< row_width
; i
++)
4597 *dp
-- = palette
[*sp
].blue
;
4598 *dp
-- = palette
[*sp
].green
;
4599 *dp
-- = palette
[*sp
].red
;
4603 row_info
->bit_depth
= 8;
4604 row_info
->pixel_depth
= 24;
4605 row_info
->rowbytes
= row_width
* 3;
4606 row_info
->color_type
= 2;
4607 row_info
->channels
= 3;
4614 /* If the bit depth < 8, it is expanded to 8. Also, if the already
4615 * expanded transparency value is supplied, an alpha channel is built.
4618 png_do_expand(png_row_infop row_info
, png_bytep row
,
4619 png_const_color_16p trans_color
)
4624 png_uint_32 row_width
=row_info
->width
;
4626 png_debug(1, "in png_do_expand");
4629 if (row_info
->color_type
== PNG_COLOR_TYPE_GRAY
)
4631 png_uint_16 gray
= (png_uint_16
)(trans_color
? trans_color
->gray
: 0);
4633 if (row_info
->bit_depth
< 8)
4635 switch (row_info
->bit_depth
)
4639 gray
= (png_uint_16
)((gray
& 0x01) * 0xff);
4640 sp
= row
+ (png_size_t
)((row_width
- 1) >> 3);
4641 dp
= row
+ (png_size_t
)row_width
- 1;
4642 shift
= 7 - (int)((row_width
+ 7) & 0x07);
4643 for (i
= 0; i
< row_width
; i
++)
4645 if ((*sp
>> shift
) & 0x01)
4667 gray
= (png_uint_16
)((gray
& 0x03) * 0x55);
4668 sp
= row
+ (png_size_t
)((row_width
- 1) >> 2);
4669 dp
= row
+ (png_size_t
)row_width
- 1;
4670 shift
= (int)((3 - ((row_width
+ 3) & 0x03)) << 1);
4671 for (i
= 0; i
< row_width
; i
++)
4673 value
= (*sp
>> shift
) & 0x03;
4674 *dp
= (png_byte
)(value
| (value
<< 2) | (value
<< 4) |
4692 gray
= (png_uint_16
)((gray
& 0x0f) * 0x11);
4693 sp
= row
+ (png_size_t
)((row_width
- 1) >> 1);
4694 dp
= row
+ (png_size_t
)row_width
- 1;
4695 shift
= (int)((1 - ((row_width
+ 1) & 0x01)) << 2);
4696 for (i
= 0; i
< row_width
; i
++)
4698 value
= (*sp
>> shift
) & 0x0f;
4699 *dp
= (png_byte
)(value
| (value
<< 4));
4718 row_info
->bit_depth
= 8;
4719 row_info
->pixel_depth
= 8;
4720 row_info
->rowbytes
= row_width
;
4723 if (trans_color
!= NULL
)
4725 if (row_info
->bit_depth
== 8)
4728 sp
= row
+ (png_size_t
)row_width
- 1;
4729 dp
= row
+ (png_size_t
)(row_width
<< 1) - 1;
4731 for (i
= 0; i
< row_width
; i
++)
4743 else if (row_info
->bit_depth
== 16)
4745 png_byte gray_high
= (png_byte
)((gray
>> 8) & 0xff);
4746 png_byte gray_low
= (png_byte
)(gray
& 0xff);
4747 sp
= row
+ row_info
->rowbytes
- 1;
4748 dp
= row
+ (row_info
->rowbytes
<< 1) - 1;
4749 for (i
= 0; i
< row_width
; i
++)
4751 if (*(sp
- 1) == gray_high
&& *(sp
) == gray_low
)
4768 row_info
->color_type
= PNG_COLOR_TYPE_GRAY_ALPHA
;
4769 row_info
->channels
= 2;
4770 row_info
->pixel_depth
= (png_byte
)(row_info
->bit_depth
<< 1);
4771 row_info
->rowbytes
= PNG_ROWBYTES(row_info
->pixel_depth
,
4775 else if (row_info
->color_type
== PNG_COLOR_TYPE_RGB
&& trans_color
)
4777 if (row_info
->bit_depth
== 8)
4779 png_byte red
= (png_byte
)(trans_color
->red
& 0xff);
4780 png_byte green
= (png_byte
)(trans_color
->green
& 0xff);
4781 png_byte blue
= (png_byte
)(trans_color
->blue
& 0xff);
4782 sp
= row
+ (png_size_t
)row_info
->rowbytes
- 1;
4783 dp
= row
+ (png_size_t
)(row_width
<< 2) - 1;
4784 for (i
= 0; i
< row_width
; i
++)
4786 if (*(sp
- 2) == red
&& *(sp
- 1) == green
&& *(sp
) == blue
)
4797 else if (row_info
->bit_depth
== 16)
4799 png_byte red_high
= (png_byte
)((trans_color
->red
>> 8) & 0xff);
4800 png_byte green_high
= (png_byte
)((trans_color
->green
>> 8) & 0xff);
4801 png_byte blue_high
= (png_byte
)((trans_color
->blue
>> 8) & 0xff);
4802 png_byte red_low
= (png_byte
)(trans_color
->red
& 0xff);
4803 png_byte green_low
= (png_byte
)(trans_color
->green
& 0xff);
4804 png_byte blue_low
= (png_byte
)(trans_color
->blue
& 0xff);
4805 sp
= row
+ row_info
->rowbytes
- 1;
4806 dp
= row
+ (png_size_t
)(row_width
<< 3) - 1;
4807 for (i
= 0; i
< row_width
; i
++)
4809 if (*(sp
- 5) == red_high
&&
4810 *(sp
- 4) == red_low
&&
4811 *(sp
- 3) == green_high
&&
4812 *(sp
- 2) == green_low
&&
4813 *(sp
- 1) == blue_high
&&
4834 row_info
->color_type
= PNG_COLOR_TYPE_RGB_ALPHA
;
4835 row_info
->channels
= 4;
4836 row_info
->pixel_depth
= (png_byte
)(row_info
->bit_depth
<< 2);
4837 row_info
->rowbytes
= PNG_ROWBYTES(row_info
->pixel_depth
, row_width
);
4843 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4844 /* If the bit depth is 8 and the color type is not a palette type expand the
4845 * whole row to 16 bits. Has no effect otherwise.
4848 png_do_expand_16(png_row_infop row_info
, png_bytep row
)
4850 if (row_info
->bit_depth
== 8 &&
4851 row_info
->color_type
!= PNG_COLOR_TYPE_PALETTE
)
4853 /* The row have a sequence of bytes containing [0..255] and we need
4854 * to turn it into another row containing [0..65535], to do this we
4857 * (input / 255) * 65535
4859 * Which happens to be exactly input * 257 and this can be achieved
4860 * simply by byte replication in place (copying backwards).
4862 png_byte
*sp
= row
+ row_info
->rowbytes
; /* source, last byte + 1 */
4863 png_byte
*dp
= sp
+ row_info
->rowbytes
; /* destination, end + 1 */
4865 dp
[-2] = dp
[-1] = *--sp
, dp
-= 2;
4867 row_info
->rowbytes
*= 2;
4868 row_info
->bit_depth
= 16;
4869 row_info
->pixel_depth
= (png_byte
)(row_info
->channels
* 16);
4874 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4876 png_do_quantize(png_row_infop row_info
, png_bytep row
,
4877 png_const_bytep palette_lookup
, png_const_bytep quantize_lookup
)
4881 png_uint_32 row_width
=row_info
->width
;
4883 png_debug(1, "in png_do_quantize");
4885 if (row_info
->bit_depth
== 8)
4887 if (row_info
->color_type
== PNG_COLOR_TYPE_RGB
&& palette_lookup
)
4892 for (i
= 0; i
< row_width
; i
++)
4898 /* This looks real messy, but the compiler will reduce
4899 * it down to a reasonable formula. For example, with
4900 * 5 bits per color, we get:
4901 * p = (((r >> 3) & 0x1f) << 10) |
4902 * (((g >> 3) & 0x1f) << 5) |
4903 * ((b >> 3) & 0x1f);
4905 p
= (((r
>> (8 - PNG_QUANTIZE_RED_BITS
)) &
4906 ((1 << PNG_QUANTIZE_RED_BITS
) - 1)) <<
4907 (PNG_QUANTIZE_GREEN_BITS
+ PNG_QUANTIZE_BLUE_BITS
)) |
4908 (((g
>> (8 - PNG_QUANTIZE_GREEN_BITS
)) &
4909 ((1 << PNG_QUANTIZE_GREEN_BITS
) - 1)) <<
4910 (PNG_QUANTIZE_BLUE_BITS
)) |
4911 ((b
>> (8 - PNG_QUANTIZE_BLUE_BITS
)) &
4912 ((1 << PNG_QUANTIZE_BLUE_BITS
) - 1));
4914 *dp
++ = palette_lookup
[p
];
4917 row_info
->color_type
= PNG_COLOR_TYPE_PALETTE
;
4918 row_info
->channels
= 1;
4919 row_info
->pixel_depth
= row_info
->bit_depth
;
4920 row_info
->rowbytes
= PNG_ROWBYTES(row_info
->pixel_depth
, row_width
);
4923 else if (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
&&
4924 palette_lookup
!= NULL
)
4929 for (i
= 0; i
< row_width
; i
++)
4936 p
= (((r
>> (8 - PNG_QUANTIZE_RED_BITS
)) &
4937 ((1 << PNG_QUANTIZE_RED_BITS
) - 1)) <<
4938 (PNG_QUANTIZE_GREEN_BITS
+ PNG_QUANTIZE_BLUE_BITS
)) |
4939 (((g
>> (8 - PNG_QUANTIZE_GREEN_BITS
)) &
4940 ((1 << PNG_QUANTIZE_GREEN_BITS
) - 1)) <<
4941 (PNG_QUANTIZE_BLUE_BITS
)) |
4942 ((b
>> (8 - PNG_QUANTIZE_BLUE_BITS
)) &
4943 ((1 << PNG_QUANTIZE_BLUE_BITS
) - 1));
4945 *dp
++ = palette_lookup
[p
];
4948 row_info
->color_type
= PNG_COLOR_TYPE_PALETTE
;
4949 row_info
->channels
= 1;
4950 row_info
->pixel_depth
= row_info
->bit_depth
;
4951 row_info
->rowbytes
= PNG_ROWBYTES(row_info
->pixel_depth
, row_width
);
4954 else if (row_info
->color_type
== PNG_COLOR_TYPE_PALETTE
&&
4959 for (i
= 0; i
< row_width
; i
++, sp
++)
4961 *sp
= quantize_lookup
[*sp
];
4966 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
4967 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
4969 #ifdef PNG_MNG_FEATURES_SUPPORTED
4970 /* Undoes intrapixel differencing */
4972 png_do_read_intrapixel(png_row_infop row_info
, png_bytep row
)
4974 png_debug(1, "in png_do_read_intrapixel");
4977 (row_info
->color_type
& PNG_COLOR_MASK_COLOR
))
4979 int bytes_per_pixel
;
4980 png_uint_32 row_width
= row_info
->width
;
4982 if (row_info
->bit_depth
== 8)
4987 if (row_info
->color_type
== PNG_COLOR_TYPE_RGB
)
4988 bytes_per_pixel
= 3;
4990 else if (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
)
4991 bytes_per_pixel
= 4;
4996 for (i
= 0, rp
= row
; i
< row_width
; i
++, rp
+= bytes_per_pixel
)
4998 *(rp
) = (png_byte
)((256 + *rp
+ *(rp
+ 1)) & 0xff);
4999 *(rp
+2) = (png_byte
)((256 + *(rp
+ 2) + *(rp
+ 1)) & 0xff);
5002 else if (row_info
->bit_depth
== 16)
5007 if (row_info
->color_type
== PNG_COLOR_TYPE_RGB
)
5008 bytes_per_pixel
= 6;
5010 else if (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
)
5011 bytes_per_pixel
= 8;
5016 for (i
= 0, rp
= row
; i
< row_width
; i
++, rp
+= bytes_per_pixel
)
5018 png_uint_32 s0
= (*(rp
) << 8) | *(rp
+ 1);
5019 png_uint_32 s1
= (*(rp
+ 2) << 8) | *(rp
+ 3);
5020 png_uint_32 s2
= (*(rp
+ 4) << 8) | *(rp
+ 5);
5021 png_uint_32 red
= (s0
+ s1
+ 65536) & 0xffff;
5022 png_uint_32 blue
= (s2
+ s1
+ 65536) & 0xffff;
5023 *(rp
) = (png_byte
)((red
>> 8) & 0xff);
5024 *(rp
+ 1) = (png_byte
)(red
& 0xff);
5025 *(rp
+ 4) = (png_byte
)((blue
>> 8) & 0xff);
5026 *(rp
+ 5) = (png_byte
)(blue
& 0xff);
5031 #endif /* PNG_MNG_FEATURES_SUPPORTED */
5032 #endif /* PNG_READ_SUPPORTED */