2
/* png.c - location for general purpose libpng functions
4
* Last changed in libpng 1.6.19 [November 12, 2015]
5
* Copyright (c) 1998-2015 Glenn Randers-Pehrson
6
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
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* This code is released under the libpng license.
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* For conditions of distribution and use, see the disclaimer
11
* and license in png.h
16
/* Generate a compiler error if there is an old png.h in the search path. */
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typedef png_libpng_version_1_6_19 Your_png_h_is_not_version_1_6_19;
19
/* Tells libpng that we have already handled the first "num_bytes" bytes
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* of the PNG file signature. If the PNG data is embedded into another
21
* stream we can set num_bytes = 8 so that libpng will not attempt to read
22
* or write any of the magic bytes before it starts on the IHDR.
25
#ifdef PNG_READ_SUPPORTED
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png_set_sig_bytes(png_structrp png_ptr, int num_bytes)
29
unsigned int nb = (unsigned int)num_bytes;
31
png_debug(1, "in png_set_sig_bytes");
40
png_error(png_ptr, "Too many bytes for PNG signature");
42
png_ptr->sig_bytes = (png_byte)nb;
45
/* Checks whether the supplied bytes match the PNG signature. We allow
46
* checking less than the full 8-byte signature so that those apps that
47
* already read the first few bytes of a file to determine the file type
48
* can simply check the remaining bytes for extra assurance. Returns
49
* an integer less than, equal to, or greater than zero if sig is found,
50
* respectively, to be less than, to match, or be greater than the correct
51
* PNG signature (this is the same behavior as strcmp, memcmp, etc).
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png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check)
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png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
61
else if (num_to_check < 1)
67
if (start + num_to_check > 8)
68
num_to_check = 8 - start;
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return ((int)(memcmp(&sig[start], &png_signature[start], num_to_check)));
75
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
76
/* Function to allocate memory for zlib */
77
PNG_FUNCTION(voidpf /* PRIVATE */,
78
png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED)
80
png_alloc_size_t num_bytes = size;
85
if (items >= (~(png_alloc_size_t)0)/size)
87
png_warning (png_voidcast(png_structrp, png_ptr),
88
"Potential overflow in png_zalloc()");
93
return png_malloc_warn(png_voidcast(png_structrp, png_ptr), num_bytes);
96
/* Function to free memory for zlib */
98
png_zfree(voidpf png_ptr, voidpf ptr)
100
png_free(png_voidcast(png_const_structrp,png_ptr), ptr);
103
/* Reset the CRC variable to 32 bits of 1's. Care must be taken
104
* in case CRC is > 32 bits to leave the top bits 0.
107
png_reset_crc(png_structrp png_ptr)
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/* The cast is safe because the crc is a 32-bit value. */
110
png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0);
113
/* Calculate the CRC over a section of data. We can only pass as
114
* much data to this routine as the largest single buffer size. We
115
* also check that this data will actually be used before going to the
116
* trouble of calculating it.
119
png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length)
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if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
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if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
126
(PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
132
if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
136
/* 'uLong' is defined in zlib.h as unsigned long; this means that on some
137
* systems it is a 64-bit value. crc32, however, returns 32 bits so the
138
* following cast is safe. 'uInt' may be no more than 16 bits, so it is
139
* necessary to perform a loop here.
141
if (need_crc != 0 && length > 0)
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uLong crc = png_ptr->crc; /* Should never issue a warning */
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uInt safe_length = (uInt)length;
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if (safe_length == 0)
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safe_length = (uInt)-1; /* evil, but safe */
153
crc = crc32(crc, ptr, safe_length);
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/* The following should never issue compiler warnings; if they do the
156
* target system has characteristics that will probably violate other
157
* assumptions within the libpng code.
160
length -= safe_length;
164
/* And the following is always safe because the crc is only 32 bits. */
165
png_ptr->crc = (png_uint_32)crc;
169
/* Check a user supplied version number, called from both read and write
170
* functions that create a png_struct.
173
png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver)
175
/* Libpng versions 1.0.0 and later are binary compatible if the version
176
* string matches through the second '.'; we must recompile any
177
* applications that use any older library version.
180
if (user_png_ver != NULL)
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if (user_png_ver[i] != PNG_LIBPNG_VER_STRING[i])
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png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
190
if (user_png_ver[i] == '.')
192
} while (found_dots < 2 && user_png_ver[i] != 0 &&
193
PNG_LIBPNG_VER_STRING[i] != 0);
197
png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
199
if ((png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) != 0)
201
#ifdef PNG_WARNINGS_SUPPORTED
205
pos = png_safecat(m, (sizeof m), pos,
206
"Application built with libpng-");
207
pos = png_safecat(m, (sizeof m), pos, user_png_ver);
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pos = png_safecat(m, (sizeof m), pos, " but running with ");
209
pos = png_safecat(m, (sizeof m), pos, PNG_LIBPNG_VER_STRING);
212
png_warning(png_ptr, m);
215
#ifdef PNG_ERROR_NUMBERS_SUPPORTED
222
/* Success return. */
226
/* Generic function to create a png_struct for either read or write - this
227
* contains the common initialization.
229
PNG_FUNCTION(png_structp /* PRIVATE */,
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png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
231
png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
232
png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
234
png_struct create_struct;
235
# ifdef PNG_SETJMP_SUPPORTED
236
jmp_buf create_jmp_buf;
239
/* This temporary stack-allocated structure is used to provide a place to
240
* build enough context to allow the user provided memory allocator (if any)
243
memset(&create_struct, 0, (sizeof create_struct));
245
/* Added at libpng-1.2.6 */
246
# ifdef PNG_USER_LIMITS_SUPPORTED
247
create_struct.user_width_max = PNG_USER_WIDTH_MAX;
248
create_struct.user_height_max = PNG_USER_HEIGHT_MAX;
250
# ifdef PNG_USER_CHUNK_CACHE_MAX
251
/* Added at libpng-1.2.43 and 1.4.0 */
252
create_struct.user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
255
# ifdef PNG_USER_CHUNK_MALLOC_MAX
256
/* Added at libpng-1.2.43 and 1.4.1, required only for read but exists
257
* in png_struct regardless.
259
create_struct.user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
263
/* The following two API calls simply set fields in png_struct, so it is safe
264
* to do them now even though error handling is not yet set up.
266
# ifdef PNG_USER_MEM_SUPPORTED
267
png_set_mem_fn(&create_struct, mem_ptr, malloc_fn, free_fn);
270
PNG_UNUSED(malloc_fn)
274
/* (*error_fn) can return control to the caller after the error_ptr is set,
275
* this will result in a memory leak unless the error_fn does something
276
* extremely sophisticated. The design lacks merit but is implicit in the
279
png_set_error_fn(&create_struct, error_ptr, error_fn, warn_fn);
281
# ifdef PNG_SETJMP_SUPPORTED
282
if (!setjmp(create_jmp_buf))
285
# ifdef PNG_SETJMP_SUPPORTED
286
/* Temporarily fake out the longjmp information until we have
287
* successfully completed this function. This only works if we have
288
* setjmp() support compiled in, but it is safe - this stuff should
291
create_struct.jmp_buf_ptr = &create_jmp_buf;
292
create_struct.jmp_buf_size = 0; /*stack allocation*/
293
create_struct.longjmp_fn = longjmp;
295
/* Call the general version checker (shared with read and write code):
297
if (png_user_version_check(&create_struct, user_png_ver) != 0)
299
png_structrp png_ptr = png_voidcast(png_structrp,
300
png_malloc_warn(&create_struct, (sizeof *png_ptr)));
304
/* png_ptr->zstream holds a back-pointer to the png_struct, so
305
* this can only be done now:
307
create_struct.zstream.zalloc = png_zalloc;
308
create_struct.zstream.zfree = png_zfree;
309
create_struct.zstream.opaque = png_ptr;
311
# ifdef PNG_SETJMP_SUPPORTED
312
/* Eliminate the local error handling: */
313
create_struct.jmp_buf_ptr = NULL;
314
create_struct.jmp_buf_size = 0;
315
create_struct.longjmp_fn = 0;
318
*png_ptr = create_struct;
320
/* This is the successful return point */
326
/* A longjmp because of a bug in the application storage allocator or a
327
* simple failure to allocate the png_struct.
332
/* Allocate the memory for an info_struct for the application. */
333
PNG_FUNCTION(png_infop,PNGAPI
334
png_create_info_struct,(png_const_structrp png_ptr),PNG_ALLOCATED)
338
png_debug(1, "in png_create_info_struct");
343
/* Use the internal API that does not (or at least should not) error out, so
344
* that this call always returns ok. The application typically sets up the
345
* error handling *after* creating the info_struct because this is the way it
346
* has always been done in 'example.c'.
348
info_ptr = png_voidcast(png_inforp, png_malloc_base(png_ptr,
349
(sizeof *info_ptr)));
351
if (info_ptr != NULL)
352
memset(info_ptr, 0, (sizeof *info_ptr));
357
/* This function frees the memory associated with a single info struct.
358
* Normally, one would use either png_destroy_read_struct() or
359
* png_destroy_write_struct() to free an info struct, but this may be
360
* useful for some applications. From libpng 1.6.0 this function is also used
361
* internally to implement the png_info release part of the 'struct' destroy
362
* APIs. This ensures that all possible approaches free the same data (all of
366
png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr)
368
png_inforp info_ptr = NULL;
370
png_debug(1, "in png_destroy_info_struct");
375
if (info_ptr_ptr != NULL)
376
info_ptr = *info_ptr_ptr;
378
if (info_ptr != NULL)
380
/* Do this first in case of an error below; if the app implements its own
381
* memory management this can lead to png_free calling png_error, which
382
* will abort this routine and return control to the app error handler.
383
* An infinite loop may result if it then tries to free the same info
386
*info_ptr_ptr = NULL;
388
png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
389
memset(info_ptr, 0, (sizeof *info_ptr));
390
png_free(png_ptr, info_ptr);
394
/* Initialize the info structure. This is now an internal function (0.89)
395
* and applications using it are urged to use png_create_info_struct()
396
* instead. Use deprecated in 1.6.0, internal use removed (used internally it
399
* NOTE: it is almost inconceivable that this API is used because it bypasses
400
* the user-memory mechanism and the user error handling/warning mechanisms in
401
* those cases where it does anything other than a memset.
403
PNG_FUNCTION(void,PNGAPI
404
png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size),
407
png_inforp info_ptr = *ptr_ptr;
409
png_debug(1, "in png_info_init_3");
411
if (info_ptr == NULL)
414
if ((sizeof (png_info)) > png_info_struct_size)
417
/* The following line is why this API should not be used: */
419
info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL,
420
(sizeof *info_ptr)));
421
if (info_ptr == NULL)
426
/* Set everything to 0 */
427
memset(info_ptr, 0, (sizeof *info_ptr));
430
/* The following API is not called internally */
432
png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr,
433
int freer, png_uint_32 mask)
435
png_debug(1, "in png_data_freer");
437
if (png_ptr == NULL || info_ptr == NULL)
440
if (freer == PNG_DESTROY_WILL_FREE_DATA)
441
info_ptr->free_me |= mask;
443
else if (freer == PNG_USER_WILL_FREE_DATA)
444
info_ptr->free_me &= ~mask;
447
png_error(png_ptr, "Unknown freer parameter in png_data_freer");
451
png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
454
png_debug(1, "in png_free_data");
456
if (png_ptr == NULL || info_ptr == NULL)
459
#ifdef PNG_TEXT_SUPPORTED
460
/* Free text item num or (if num == -1) all text items */
461
if (info_ptr->text != 0 &&
462
((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0)
466
png_free(png_ptr, info_ptr->text[num].key);
467
info_ptr->text[num].key = NULL;
474
for (i = 0; i < info_ptr->num_text; i++)
475
png_free(png_ptr, info_ptr->text[i].key);
477
png_free(png_ptr, info_ptr->text);
478
info_ptr->text = NULL;
479
info_ptr->num_text = 0;
484
#ifdef PNG_tRNS_SUPPORTED
485
/* Free any tRNS entry */
486
if (((mask & PNG_FREE_TRNS) & info_ptr->free_me) != 0)
488
info_ptr->valid &= ~PNG_INFO_tRNS;
489
png_free(png_ptr, info_ptr->trans_alpha);
490
info_ptr->trans_alpha = NULL;
491
info_ptr->num_trans = 0;
495
#ifdef PNG_sCAL_SUPPORTED
496
/* Free any sCAL entry */
497
if (((mask & PNG_FREE_SCAL) & info_ptr->free_me) != 0)
499
png_free(png_ptr, info_ptr->scal_s_width);
500
png_free(png_ptr, info_ptr->scal_s_height);
501
info_ptr->scal_s_width = NULL;
502
info_ptr->scal_s_height = NULL;
503
info_ptr->valid &= ~PNG_INFO_sCAL;
507
#ifdef PNG_pCAL_SUPPORTED
508
/* Free any pCAL entry */
509
if (((mask & PNG_FREE_PCAL) & info_ptr->free_me) != 0)
511
png_free(png_ptr, info_ptr->pcal_purpose);
512
png_free(png_ptr, info_ptr->pcal_units);
513
info_ptr->pcal_purpose = NULL;
514
info_ptr->pcal_units = NULL;
516
if (info_ptr->pcal_params != NULL)
520
for (i = 0; i < info_ptr->pcal_nparams; i++)
521
png_free(png_ptr, info_ptr->pcal_params[i]);
523
png_free(png_ptr, info_ptr->pcal_params);
524
info_ptr->pcal_params = NULL;
526
info_ptr->valid &= ~PNG_INFO_pCAL;
530
#ifdef PNG_iCCP_SUPPORTED
531
/* Free any profile entry */
532
if (((mask & PNG_FREE_ICCP) & info_ptr->free_me) != 0)
534
png_free(png_ptr, info_ptr->iccp_name);
535
png_free(png_ptr, info_ptr->iccp_profile);
536
info_ptr->iccp_name = NULL;
537
info_ptr->iccp_profile = NULL;
538
info_ptr->valid &= ~PNG_INFO_iCCP;
542
#ifdef PNG_sPLT_SUPPORTED
543
/* Free a given sPLT entry, or (if num == -1) all sPLT entries */
544
if (info_ptr->splt_palettes != 0 &&
545
((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0)
549
png_free(png_ptr, info_ptr->splt_palettes[num].name);
550
png_free(png_ptr, info_ptr->splt_palettes[num].entries);
551
info_ptr->splt_palettes[num].name = NULL;
552
info_ptr->splt_palettes[num].entries = NULL;
559
for (i = 0; i < info_ptr->splt_palettes_num; i++)
561
png_free(png_ptr, info_ptr->splt_palettes[i].name);
562
png_free(png_ptr, info_ptr->splt_palettes[i].entries);
565
png_free(png_ptr, info_ptr->splt_palettes);
566
info_ptr->splt_palettes = NULL;
567
info_ptr->splt_palettes_num = 0;
568
info_ptr->valid &= ~PNG_INFO_sPLT;
573
#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
574
if (info_ptr->unknown_chunks != 0 &&
575
((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0)
579
png_free(png_ptr, info_ptr->unknown_chunks[num].data);
580
info_ptr->unknown_chunks[num].data = NULL;
587
for (i = 0; i < info_ptr->unknown_chunks_num; i++)
588
png_free(png_ptr, info_ptr->unknown_chunks[i].data);
590
png_free(png_ptr, info_ptr->unknown_chunks);
591
info_ptr->unknown_chunks = NULL;
592
info_ptr->unknown_chunks_num = 0;
597
#ifdef PNG_hIST_SUPPORTED
598
/* Free any hIST entry */
599
if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0)
601
png_free(png_ptr, info_ptr->hist);
602
info_ptr->hist = NULL;
603
info_ptr->valid &= ~PNG_INFO_hIST;
607
/* Free any PLTE entry that was internally allocated */
608
if (((mask & PNG_FREE_PLTE) & info_ptr->free_me) != 0)
610
png_free(png_ptr, info_ptr->palette);
611
info_ptr->palette = NULL;
612
info_ptr->valid &= ~PNG_INFO_PLTE;
613
info_ptr->num_palette = 0;
616
#ifdef PNG_INFO_IMAGE_SUPPORTED
617
/* Free any image bits attached to the info structure */
618
if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
620
if (info_ptr->row_pointers != 0)
623
for (row = 0; row < info_ptr->height; row++)
624
png_free(png_ptr, info_ptr->row_pointers[row]);
626
png_free(png_ptr, info_ptr->row_pointers);
627
info_ptr->row_pointers = NULL;
629
info_ptr->valid &= ~PNG_INFO_IDAT;
634
mask &= ~PNG_FREE_MUL;
636
info_ptr->free_me &= ~mask;
638
#endif /* READ || WRITE */
640
/* This function returns a pointer to the io_ptr associated with the user
641
* functions. The application should free any memory associated with this
642
* pointer before png_write_destroy() or png_read_destroy() are called.
645
png_get_io_ptr(png_const_structrp png_ptr)
650
return (png_ptr->io_ptr);
653
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
654
# ifdef PNG_STDIO_SUPPORTED
655
/* Initialize the default input/output functions for the PNG file. If you
656
* use your own read or write routines, you can call either png_set_read_fn()
657
* or png_set_write_fn() instead of png_init_io(). If you have defined
658
* PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a
659
* function of your own because "FILE *" isn't necessarily available.
662
png_init_io(png_structrp png_ptr, png_FILE_p fp)
664
png_debug(1, "in png_init_io");
669
png_ptr->io_ptr = (png_voidp)fp;
673
# ifdef PNG_SAVE_INT_32_SUPPORTED
674
/* PNG signed integers are saved in 32-bit 2's complement format. ANSI C-90
675
* defines a cast of a signed integer to an unsigned integer either to preserve
676
* the value, if it is positive, or to calculate:
678
* (UNSIGNED_MAX+1) + integer
680
* Where UNSIGNED_MAX is the appropriate maximum unsigned value, so when the
681
* negative integral value is added the result will be an unsigned value
682
* correspnding to the 2's complement representation.
685
png_save_int_32(png_bytep buf, png_int_32 i)
687
png_save_uint_32(buf, i);
691
# ifdef PNG_TIME_RFC1123_SUPPORTED
692
/* Convert the supplied time into an RFC 1123 string suitable for use in
693
* a "Creation Time" or other text-based time string.
696
png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime)
698
static PNG_CONST char short_months[12][4] =
699
{"Jan", "Feb", "Mar", "Apr", "May", "Jun",
700
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
705
if (ptime->year > 9999 /* RFC1123 limitation */ ||
706
ptime->month == 0 || ptime->month > 12 ||
707
ptime->day == 0 || ptime->day > 31 ||
708
ptime->hour > 23 || ptime->minute > 59 ||
714
char number_buf[5]; /* enough for a four-digit year */
716
# define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string))
717
# define APPEND_NUMBER(format, value)\
718
APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
719
# define APPEND(ch) if (pos < 28) out[pos++] = (ch)
721
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day);
723
APPEND_STRING(short_months[(ptime->month - 1)]);
725
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year);
727
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour);
729
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute);
731
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second);
732
APPEND_STRING(" +0000"); /* This reliably terminates the buffer */
736
# undef APPEND_NUMBER
737
# undef APPEND_STRING
743
# if PNG_LIBPNG_VER < 10700
744
/* To do: remove the following from libpng-1.7 */
745
/* Original API that uses a private buffer in png_struct.
746
* Deprecated because it causes png_struct to carry a spurious temporary
747
* buffer (png_struct::time_buffer), better to have the caller pass this in.
749
png_const_charp PNGAPI
750
png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime)
754
/* The only failure above if png_ptr != NULL is from an invalid ptime */
755
if (png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime) == 0)
756
png_warning(png_ptr, "Ignoring invalid time value");
759
return png_ptr->time_buffer;
764
# endif /* LIBPNG_VER < 10700 */
765
# endif /* TIME_RFC1123 */
767
#endif /* READ || WRITE */
769
png_const_charp PNGAPI
770
png_get_copyright(png_const_structrp png_ptr)
772
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
773
#ifdef PNG_STRING_COPYRIGHT
774
return PNG_STRING_COPYRIGHT
777
return PNG_STRING_NEWLINE \
778
"libpng version 1.6.19 - November 12, 2015" PNG_STRING_NEWLINE \
779
"Copyright (c) 1998-2015 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
780
"Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
781
"Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
784
return "libpng version 1.6.19 - November 12, 2015\
785
Copyright (c) 1998-2015 Glenn Randers-Pehrson\
786
Copyright (c) 1996-1997 Andreas Dilger\
787
Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
792
/* The following return the library version as a short string in the
793
* format 1.0.0 through 99.99.99zz. To get the version of *.h files
794
* used with your application, print out PNG_LIBPNG_VER_STRING, which
795
* is defined in png.h.
796
* Note: now there is no difference between png_get_libpng_ver() and
797
* png_get_header_ver(). Due to the version_nn_nn_nn typedef guard,
798
* it is guaranteed that png.c uses the correct version of png.h.
800
png_const_charp PNGAPI
801
png_get_libpng_ver(png_const_structrp png_ptr)
803
/* Version of *.c files used when building libpng */
804
return png_get_header_ver(png_ptr);
807
png_const_charp PNGAPI
808
png_get_header_ver(png_const_structrp png_ptr)
810
/* Version of *.h files used when building libpng */
811
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
812
return PNG_LIBPNG_VER_STRING;
815
png_const_charp PNGAPI
816
png_get_header_version(png_const_structrp png_ptr)
818
/* Returns longer string containing both version and date */
819
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
821
return PNG_HEADER_VERSION_STRING
822
# ifndef PNG_READ_SUPPORTED
827
return PNG_HEADER_VERSION_STRING;
831
#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
832
/* NOTE: this routine is not used internally! */
833
/* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
834
* large of png_color. This lets grayscale images be treated as
835
* paletted. Most useful for gamma correction and simplification
836
* of code. This API is not used internally.
839
png_build_grayscale_palette(int bit_depth, png_colorp palette)
846
png_debug(1, "in png_do_build_grayscale_palette");
879
for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
881
palette[i].red = (png_byte)(v & 0xff);
882
palette[i].green = (png_byte)(v & 0xff);
883
palette[i].blue = (png_byte)(v & 0xff);
888
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
890
png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name)
892
/* Check chunk_name and return "keep" value if it's on the list, else 0 */
893
png_const_bytep p, p_end;
895
if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list == 0)
896
return PNG_HANDLE_CHUNK_AS_DEFAULT;
898
p_end = png_ptr->chunk_list;
899
p = p_end + png_ptr->num_chunk_list*5; /* beyond end */
901
/* The code is the fifth byte after each four byte string. Historically this
902
* code was always searched from the end of the list, this is no longer
903
* necessary because the 'set' routine handles duplicate entries correcty.
905
do /* num_chunk_list > 0, so at least one */
909
if (memcmp(chunk_name, p, 4) == 0)
914
/* This means that known chunks should be processed and unknown chunks should
915
* be handled according to the value of png_ptr->unknown_default; this can be
916
* confusing because, as a result, there are two levels of defaulting for
919
return PNG_HANDLE_CHUNK_AS_DEFAULT;
922
#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
923
defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
925
png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name)
927
png_byte chunk_string[5];
929
PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
930
return png_handle_as_unknown(png_ptr, chunk_string);
932
#endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */
933
#endif /* SET_UNKNOWN_CHUNKS */
935
#ifdef PNG_READ_SUPPORTED
936
/* This function, added to libpng-1.0.6g, is untested. */
938
png_reset_zstream(png_structrp png_ptr)
941
return Z_STREAM_ERROR;
943
/* WARNING: this resets the window bits to the maximum! */
944
return (inflateReset(&png_ptr->zstream));
948
/* This function was added to libpng-1.0.7 */
950
png_access_version_number(void)
952
/* Version of *.c files used when building libpng */
953
return((png_uint_32)PNG_LIBPNG_VER);
956
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
957
/* Ensure that png_ptr->zstream.msg holds some appropriate error message string.
958
* If it doesn't 'ret' is used to set it to something appropriate, even in cases
959
* like Z_OK or Z_STREAM_END where the error code is apparently a success code.
962
png_zstream_error(png_structrp png_ptr, int ret)
964
/* Translate 'ret' into an appropriate error string, priority is given to the
965
* one in zstream if set. This always returns a string, even in cases like
966
* Z_OK or Z_STREAM_END where the error code is a success code.
968
if (png_ptr->zstream.msg == NULL) switch (ret)
972
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return code");
977
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected end of LZ stream");
981
/* This means the deflate stream did not have a dictionary; this
982
* indicates a bogus PNG.
984
png_ptr->zstream.msg = PNGZ_MSG_CAST("missing LZ dictionary");
988
/* gz APIs only: should not happen */
989
png_ptr->zstream.msg = PNGZ_MSG_CAST("zlib IO error");
993
/* internal libpng error */
994
png_ptr->zstream.msg = PNGZ_MSG_CAST("bad parameters to zlib");
998
png_ptr->zstream.msg = PNGZ_MSG_CAST("damaged LZ stream");
1002
png_ptr->zstream.msg = PNGZ_MSG_CAST("insufficient memory");
1006
/* End of input or output; not a problem if the caller is doing
1007
* incremental read or write.
1009
png_ptr->zstream.msg = PNGZ_MSG_CAST("truncated");
1012
case Z_VERSION_ERROR:
1013
png_ptr->zstream.msg = PNGZ_MSG_CAST("unsupported zlib version");
1016
case PNG_UNEXPECTED_ZLIB_RETURN:
1017
/* Compile errors here mean that zlib now uses the value co-opted in
1018
* pngpriv.h for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above
1019
* and change pngpriv.h. Note that this message is "... return",
1020
* whereas the default/Z_OK one is "... return code".
1022
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return");
1027
/* png_convert_size: a PNGAPI but no longer in png.h, so deleted
1031
/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
1032
#ifdef PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */
1034
png_colorspace_check_gamma(png_const_structrp png_ptr,
1035
png_colorspacerp colorspace, png_fixed_point gAMA, int from)
1036
/* This is called to check a new gamma value against an existing one. The
1037
* routine returns false if the new gamma value should not be written.
1039
* 'from' says where the new gamma value comes from:
1041
* 0: the new gamma value is the libpng estimate for an ICC profile
1042
* 1: the new gamma value comes from a gAMA chunk
1043
* 2: the new gamma value comes from an sRGB chunk
1046
png_fixed_point gtest;
1048
if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
1049
(png_muldiv(>est, colorspace->gamma, PNG_FP_1, gAMA) == 0 ||
1050
png_gamma_significant(gtest) != 0))
1052
/* Either this is an sRGB image, in which case the calculated gamma
1053
* approximation should match, or this is an image with a profile and the
1054
* value libpng calculates for the gamma of the profile does not match the
1055
* value recorded in the file. The former, sRGB, case is an error, the
1056
* latter is just a warning.
1058
if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2)
1060
png_chunk_report(png_ptr, "gamma value does not match sRGB",
1062
/* Do not overwrite an sRGB value */
1066
else /* sRGB tag not involved */
1068
png_chunk_report(png_ptr, "gamma value does not match libpng estimate",
1078
png_colorspace_set_gamma(png_const_structrp png_ptr,
1079
png_colorspacerp colorspace, png_fixed_point gAMA)
1081
/* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
1082
* occur. Since the fixed point representation is asymetrical it is
1083
* possible for 1/gamma to overflow the limit of 21474 and this means the
1084
* gamma value must be at least 5/100000 and hence at most 20000.0. For
1085
* safety the limits here are a little narrower. The values are 0.00016 to
1086
* 6250.0, which are truly ridiculous gamma values (and will produce
1087
* displays that are all black or all white.)
1089
* In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk
1090
* handling code, which only required the value to be >0.
1092
png_const_charp errmsg;
1094
if (gAMA < 16 || gAMA > 625000000)
1095
errmsg = "gamma value out of range";
1097
# ifdef PNG_READ_gAMA_SUPPORTED
1098
/* Allow the application to set the gamma value more than once */
1099
else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
1100
(colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0)
1101
errmsg = "duplicate";
1104
/* Do nothing if the colorspace is already invalid */
1105
else if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
1110
if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA,
1111
1/*from gAMA*/) != 0)
1113
/* Store this gamma value. */
1114
colorspace->gamma = gAMA;
1115
colorspace->flags |=
1116
(PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA);
1119
/* At present if the check_gamma test fails the gamma of the colorspace is
1120
* not updated however the colorspace is not invalidated. This
1121
* corresponds to the case where the existing gamma comes from an sRGB
1122
* chunk or profile. An error message has already been output.
1127
/* Error exit - errmsg has been set. */
1128
colorspace->flags |= PNG_COLORSPACE_INVALID;
1129
png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR);
1133
png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr)
1135
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1137
/* Everything is invalid */
1138
info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB|
1141
# ifdef PNG_COLORSPACE_SUPPORTED
1142
/* Clean up the iCCP profile now if it won't be used. */
1143
png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, -1/*not used*/);
1151
# ifdef PNG_COLORSPACE_SUPPORTED
1152
/* Leave the INFO_iCCP flag set if the pngset.c code has already set
1153
* it; this allows a PNG to contain a profile which matches sRGB and
1154
* yet still have that profile retrievable by the application.
1156
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB) != 0)
1157
info_ptr->valid |= PNG_INFO_sRGB;
1160
info_ptr->valid &= ~PNG_INFO_sRGB;
1162
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
1163
info_ptr->valid |= PNG_INFO_cHRM;
1166
info_ptr->valid &= ~PNG_INFO_cHRM;
1169
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0)
1170
info_ptr->valid |= PNG_INFO_gAMA;
1173
info_ptr->valid &= ~PNG_INFO_gAMA;
1177
#ifdef PNG_READ_SUPPORTED
1179
png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr)
1181
if (info_ptr == NULL) /* reduce code size; check here not in the caller */
1184
info_ptr->colorspace = png_ptr->colorspace;
1185
png_colorspace_sync_info(png_ptr, info_ptr);
1190
#ifdef PNG_COLORSPACE_SUPPORTED
1191
/* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
1192
* cHRM, as opposed to using chromaticities. These internal APIs return
1193
* non-zero on a parameter error. The X, Y and Z values are required to be
1194
* positive and less than 1.0.
1197
png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
1199
png_int_32 d, dwhite, whiteX, whiteY;
1201
d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
1202
if (png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d) == 0)
1204
if (png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d) == 0)
1207
whiteX = XYZ->red_X;
1208
whiteY = XYZ->red_Y;
1210
d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
1211
if (png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d) == 0)
1213
if (png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d) == 0)
1216
whiteX += XYZ->green_X;
1217
whiteY += XYZ->green_Y;
1219
d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
1220
if (png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d) == 0)
1222
if (png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d) == 0)
1225
whiteX += XYZ->blue_X;
1226
whiteY += XYZ->blue_Y;
1228
/* The reference white is simply the sum of the end-point (X,Y,Z) vectors,
1231
if (png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite) == 0)
1233
if (png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite) == 0)
1240
png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
1242
png_fixed_point red_inverse, green_inverse, blue_scale;
1243
png_fixed_point left, right, denominator;
1245
/* Check xy and, implicitly, z. Note that wide gamut color spaces typically
1246
* have end points with 0 tristimulus values (these are impossible end
1247
* points, but they are used to cover the possible colors). We check
1248
* xy->whitey against 5, not 0, to avoid a possible integer overflow.
1250
if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1;
1251
if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1;
1252
if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1;
1253
if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1;
1254
if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1;
1255
if (xy->bluey < 0 || xy->bluey > PNG_FP_1-xy->bluex) return 1;
1256
if (xy->whitex < 0 || xy->whitex > PNG_FP_1) return 1;
1257
if (xy->whitey < 5 || xy->whitey > PNG_FP_1-xy->whitex) return 1;
1259
/* The reverse calculation is more difficult because the original tristimulus
1260
* value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8
1261
* derived values were recorded in the cHRM chunk;
1262
* (red,green,blue,white)x(x,y). This loses one degree of freedom and
1263
* therefore an arbitrary ninth value has to be introduced to undo the
1264
* original transformations.
1266
* Think of the original end-points as points in (X,Y,Z) space. The
1267
* chromaticity values (c) have the property:
1273
* For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the
1274
* three chromaticity values (x,y,z) for each end-point obey the
1279
* This describes the plane in (X,Y,Z) space that intersects each axis at the
1280
* value 1.0; call this the chromaticity plane. Thus the chromaticity
1281
* calculation has scaled each end-point so that it is on the x+y+z=1 plane
1282
* and chromaticity is the intersection of the vector from the origin to the
1283
* (X,Y,Z) value with the chromaticity plane.
1285
* To fully invert the chromaticity calculation we would need the three
1286
* end-point scale factors, (red-scale, green-scale, blue-scale), but these
1287
* were not recorded. Instead we calculated the reference white (X,Y,Z) and
1288
* recorded the chromaticity of this. The reference white (X,Y,Z) would have
1289
* given all three of the scale factors since:
1291
* color-C = color-c * color-scale
1292
* white-C = red-C + green-C + blue-C
1293
* = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
1295
* But cHRM records only white-x and white-y, so we have lost the white scale
1298
* white-C = white-c*white-scale
1300
* To handle this the inverse transformation makes an arbitrary assumption
1301
* about white-scale:
1303
* Assume: white-Y = 1.0
1304
* Hence: white-scale = 1/white-y
1305
* Or: red-Y + green-Y + blue-Y = 1.0
1307
* Notice the last statement of the assumption gives an equation in three of
1308
* the nine values we want to calculate. 8 more equations come from the
1309
* above routine as summarised at the top above (the chromaticity
1312
* Given: color-x = color-X / (color-X + color-Y + color-Z)
1313
* Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0
1315
* This is 9 simultaneous equations in the 9 variables "color-C" and can be
1316
* solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix
1317
* determinants, however this is not as bad as it seems because only 28 of
1318
* the total of 90 terms in the various matrices are non-zero. Nevertheless
1319
* Cramer's rule is notoriously numerically unstable because the determinant
1320
* calculation involves the difference of large, but similar, numbers. It is
1321
* difficult to be sure that the calculation is stable for real world values
1322
* and it is certain that it becomes unstable where the end points are close
1325
* So this code uses the perhaps slightly less optimal but more
1326
* understandable and totally obvious approach of calculating color-scale.
1328
* This algorithm depends on the precision in white-scale and that is
1329
* (1/white-y), so we can immediately see that as white-y approaches 0 the
1330
* accuracy inherent in the cHRM chunk drops off substantially.
1332
* libpng arithmetic: a simple inversion of the above equations
1333
* ------------------------------------------------------------
1335
* white_scale = 1/white-y
1336
* white-X = white-x * white-scale
1338
* white-Z = (1 - white-x - white-y) * white_scale
1340
* white-C = red-C + green-C + blue-C
1341
* = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
1343
* This gives us three equations in (red-scale,green-scale,blue-scale) where
1344
* all the coefficients are now known:
1346
* red-x*red-scale + green-x*green-scale + blue-x*blue-scale
1348
* red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1
1349
* red-z*red-scale + green-z*green-scale + blue-z*blue-scale
1350
* = (1 - white-x - white-y)/white-y
1352
* In the last equation color-z is (1 - color-x - color-y) so we can add all
1353
* three equations together to get an alternative third:
1355
* red-scale + green-scale + blue-scale = 1/white-y = white-scale
1357
* So now we have a Cramer's rule solution where the determinants are just
1358
* 3x3 - far more tractible. Unfortunately 3x3 determinants still involve
1359
* multiplication of three coefficients so we can't guarantee to avoid
1360
* overflow in the libpng fixed point representation. Using Cramer's rule in
1361
* floating point is probably a good choice here, but it's not an option for
1362
* fixed point. Instead proceed to simplify the first two equations by
1363
* eliminating what is likely to be the largest value, blue-scale:
1365
* blue-scale = white-scale - red-scale - green-scale
1369
* (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale =
1370
* (white-x - blue-x)*white-scale
1372
* (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale =
1373
* 1 - blue-y*white-scale
1375
* And now we can trivially solve for (red-scale,green-scale):
1378
* (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale
1379
* -----------------------------------------------------------
1383
* 1 - blue-y*white-scale - (green-y - blue-y) * green-scale
1384
* ---------------------------------------------------------
1390
* ( (green-x - blue-x) * (white-y - blue-y) -
1391
* (green-y - blue-y) * (white-x - blue-x) ) / white-y
1392
* -------------------------------------------------------------------------
1393
* (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
1396
* ( (red-y - blue-y) * (white-x - blue-x) -
1397
* (red-x - blue-x) * (white-y - blue-y) ) / white-y
1398
* -------------------------------------------------------------------------
1399
* (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
1402
* The input values have 5 decimal digits of accuracy. The values are all in
1403
* the range 0 < value < 1, so simple products are in the same range but may
1404
* need up to 10 decimal digits to preserve the original precision and avoid
1405
* underflow. Because we are using a 32-bit signed representation we cannot
1406
* match this; the best is a little over 9 decimal digits, less than 10.
1408
* The approach used here is to preserve the maximum precision within the
1409
* signed representation. Because the red-scale calculation above uses the
1410
* difference between two products of values that must be in the range -1..+1
1411
* it is sufficient to divide the product by 7; ceil(100,000/32767*2). The
1412
* factor is irrelevant in the calculation because it is applied to both
1413
* numerator and denominator.
1415
* Note that the values of the differences of the products of the
1416
* chromaticities in the above equations tend to be small, for example for
1417
* the sRGB chromaticities they are:
1419
* red numerator: -0.04751
1420
* green numerator: -0.08788
1421
* denominator: -0.2241 (without white-y multiplication)
1423
* The resultant Y coefficients from the chromaticities of some widely used
1424
* color space definitions are (to 15 decimal places):
1427
* 0.212639005871510 0.715168678767756 0.072192315360734
1429
* 0.288071128229293 0.711843217810102 0.000085653960605
1431
* 0.297344975250536 0.627363566255466 0.075291458493998
1432
* Adobe Wide Gamut RGB
1433
* 0.258728243040113 0.724682314948566 0.016589442011321
1435
/* By the argument, above overflow should be impossible here. The return
1436
* value of 2 indicates an internal error to the caller.
1438
if (png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7) == 0)
1440
if (png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7) == 0)
1442
denominator = left - right;
1444
/* Now find the red numerator. */
1445
if (png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
1447
if (png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
1450
/* Overflow is possible here and it indicates an extreme set of PNG cHRM
1451
* chunk values. This calculation actually returns the reciprocal of the
1452
* scale value because this allows us to delay the multiplication of white-y
1453
* into the denominator, which tends to produce a small number.
1455
if (png_muldiv(&red_inverse, xy->whitey, denominator, left-right) == 0 ||
1456
red_inverse <= xy->whitey /* r+g+b scales = white scale */)
1459
/* Similarly for green_inverse: */
1460
if (png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
1462
if (png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
1464
if (png_muldiv(&green_inverse, xy->whitey, denominator, left-right) == 0 ||
1465
green_inverse <= xy->whitey)
1468
/* And the blue scale, the checks above guarantee this can't overflow but it
1469
* can still produce 0 for extreme cHRM values.
1471
blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) -
1472
png_reciprocal(green_inverse);
1473
if (blue_scale <= 0)
1477
/* And fill in the png_XYZ: */
1478
if (png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse) == 0)
1480
if (png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse) == 0)
1482
if (png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
1486
if (png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse) == 0)
1488
if (png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse) == 0)
1490
if (png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
1491
green_inverse) == 0)
1494
if (png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1) == 0)
1496
if (png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1) == 0)
1498
if (png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
1502
return 0; /*success*/
1506
png_XYZ_normalize(png_XYZ *XYZ)
1510
if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 ||
1511
XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 ||
1512
XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0)
1515
/* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1.
1516
* IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore
1517
* relying on addition of two positive values producing a negative one is not
1521
if (0x7fffffff - Y < XYZ->green_X)
1524
if (0x7fffffff - Y < XYZ->blue_X)
1530
if (png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y) == 0)
1532
if (png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y) == 0)
1534
if (png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y) == 0)
1537
if (png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y) == 0)
1539
if (png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y) == 0)
1541
if (png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y) == 0)
1544
if (png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y) == 0)
1546
if (png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y) == 0)
1548
if (png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y) == 0)
1556
png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta)
1558
/* Allow an error of +/-0.01 (absolute value) on each chromaticity */
1559
if (PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
1560
PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
1561
PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) ||
1562
PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) ||
1563
PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
1564
PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
1565
PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) ||
1566
PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta))
1571
/* Added in libpng-1.6.0, a different check for the validity of a set of cHRM
1572
* chunk chromaticities. Earlier checks used to simply look for the overflow
1573
* condition (where the determinant of the matrix to solve for XYZ ends up zero
1574
* because the chromaticity values are not all distinct.) Despite this it is
1575
* theoretically possible to produce chromaticities that are apparently valid
1576
* but that rapidly degrade to invalid, potentially crashing, sets because of
1577
* arithmetic inaccuracies when calculations are performed on them. The new
1578
* check is to round-trip xy -> XYZ -> xy and then check that the result is
1579
* within a small percentage of the original.
1582
png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy)
1587
/* As a side-effect this routine also returns the XYZ endpoints. */
1588
result = png_XYZ_from_xy(XYZ, xy);
1592
result = png_xy_from_XYZ(&xy_test, XYZ);
1596
if (png_colorspace_endpoints_match(xy, &xy_test,
1597
5/*actually, the math is pretty accurate*/) != 0)
1604
/* This is the check going the other way. The XYZ is modified to normalize it
1605
* (another side-effect) and the xy chromaticities are returned.
1608
png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ)
1613
result = png_XYZ_normalize(XYZ);
1617
result = png_xy_from_XYZ(xy, XYZ);
1622
return png_colorspace_check_xy(&XYZtemp, xy);
1625
/* Used to check for an endpoint match against sRGB */
1626
static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */
1629
/* red */ 64000, 33000,
1630
/* green */ 30000, 60000,
1631
/* blue */ 15000, 6000,
1632
/* white */ 31270, 32900
1636
png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
1637
png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
1640
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
1643
/* The consistency check is performed on the chromaticities; this factors out
1644
* variations because of the normalization (or not) of the end point Y
1647
if (preferred < 2 &&
1648
(colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
1650
/* The end points must be reasonably close to any we already have. The
1651
* following allows an error of up to +/-.001
1653
if (png_colorspace_endpoints_match(xy, &colorspace->end_points_xy,
1656
colorspace->flags |= PNG_COLORSPACE_INVALID;
1657
png_benign_error(png_ptr, "inconsistent chromaticities");
1658
return 0; /* failed */
1661
/* Only overwrite with preferred values */
1663
return 1; /* ok, but no change */
1666
colorspace->end_points_xy = *xy;
1667
colorspace->end_points_XYZ = *XYZ;
1668
colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS;
1670
/* The end points are normally quoted to two decimal digits, so allow +/-0.01
1673
if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000) != 0)
1674
colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;
1677
colorspace->flags &= PNG_COLORSPACE_CANCEL(
1678
PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
1680
return 2; /* ok and changed */
1684
png_colorspace_set_chromaticities(png_const_structrp png_ptr,
1685
png_colorspacerp colorspace, const png_xy *xy, int preferred)
1687
/* We must check the end points to ensure they are reasonable - in the past
1688
* color management systems have crashed as a result of getting bogus
1689
* colorant values, while this isn't the fault of libpng it is the
1690
* responsibility of libpng because PNG carries the bomb and libpng is in a
1691
* position to protect against it.
1695
switch (png_colorspace_check_xy(&XYZ, xy))
1697
case 0: /* success */
1698
return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
1702
/* We can't invert the chromaticities so we can't produce value XYZ
1703
* values. Likely as not a color management system will fail too.
1705
colorspace->flags |= PNG_COLORSPACE_INVALID;
1706
png_benign_error(png_ptr, "invalid chromaticities");
1710
/* libpng is broken; this should be a warning but if it happens we
1711
* want error reports so for the moment it is an error.
1713
colorspace->flags |= PNG_COLORSPACE_INVALID;
1714
png_error(png_ptr, "internal error checking chromaticities");
1717
return 0; /* failed */
1721
png_colorspace_set_endpoints(png_const_structrp png_ptr,
1722
png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
1724
png_XYZ XYZ = *XYZ_in;
1727
switch (png_colorspace_check_XYZ(&xy, &XYZ))
1730
return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
1734
/* End points are invalid. */
1735
colorspace->flags |= PNG_COLORSPACE_INVALID;
1736
png_benign_error(png_ptr, "invalid end points");
1740
colorspace->flags |= PNG_COLORSPACE_INVALID;
1741
png_error(png_ptr, "internal error checking chromaticities");
1744
return 0; /* failed */
1747
#if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED)
1748
/* Error message generation */
1750
png_icc_tag_char(png_uint_32 byte)
1753
if (byte >= 32 && byte <= 126)
1760
png_icc_tag_name(char *name, png_uint_32 tag)
1763
name[1] = png_icc_tag_char(tag >> 24);
1764
name[2] = png_icc_tag_char(tag >> 16);
1765
name[3] = png_icc_tag_char(tag >> 8);
1766
name[4] = png_icc_tag_char(tag );
1771
is_ICC_signature_char(png_alloc_size_t it)
1773
return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) ||
1774
(it >= 97 && it <= 122);
1778
is_ICC_signature(png_alloc_size_t it)
1780
return is_ICC_signature_char(it >> 24) /* checks all the top bits */ &&
1781
is_ICC_signature_char((it >> 16) & 0xff) &&
1782
is_ICC_signature_char((it >> 8) & 0xff) &&
1783
is_ICC_signature_char(it & 0xff);
1787
png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
1788
png_const_charp name, png_alloc_size_t value, png_const_charp reason)
1791
char message[196]; /* see below for calculation */
1793
if (colorspace != NULL)
1794
colorspace->flags |= PNG_COLORSPACE_INVALID;
1796
pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
1797
pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
1798
pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
1799
if (is_ICC_signature(value) != 0)
1801
/* So 'value' is at most 4 bytes and the following cast is safe */
1802
png_icc_tag_name(message+pos, (png_uint_32)value);
1803
pos += 6; /* total +8; less than the else clause */
1804
message[pos++] = ':';
1805
message[pos++] = ' ';
1807
# ifdef PNG_WARNINGS_SUPPORTED
1810
char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/
1812
pos = png_safecat(message, (sizeof message), pos,
1813
png_format_number(number, number+(sizeof number),
1814
PNG_NUMBER_FORMAT_x, value));
1815
pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/
1818
/* The 'reason' is an arbitrary message, allow +79 maximum 195 */
1819
pos = png_safecat(message, (sizeof message), pos, reason);
1822
/* This is recoverable, but make it unconditionally an app_error on write to
1823
* avoid writing invalid ICC profiles into PNG files (i.e., we handle them
1824
* on read, with a warning, but on write unless the app turns off
1825
* application errors the PNG won't be written.)
1827
png_chunk_report(png_ptr, message,
1828
(colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
1832
#endif /* sRGB || iCCP */
1834
#ifdef PNG_sRGB_SUPPORTED
1836
png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
1839
/* sRGB sets known gamma, end points and (from the chunk) intent. */
1840
/* IMPORTANT: these are not necessarily the values found in an ICC profile
1841
* because ICC profiles store values adapted to a D50 environment; it is
1842
* expected that the ICC profile mediaWhitePointTag will be D50; see the
1843
* checks and code elsewhere to understand this better.
1845
* These XYZ values, which are accurate to 5dp, produce rgb to gray
1846
* coefficients of (6968,23435,2366), which are reduced (because they add up
1847
* to 32769 not 32768) to (6968,23434,2366). These are the values that
1848
* libpng has traditionally used (and are the best values given the 15bit
1849
* algorithm used by the rgb to gray code.)
1851
static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */
1854
/* red */ 41239, 21264, 1933,
1855
/* green */ 35758, 71517, 11919,
1856
/* blue */ 18048, 7219, 95053
1859
/* Do nothing if the colorspace is already invalidated. */
1860
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
1863
/* Check the intent, then check for existing settings. It is valid for the
1864
* PNG file to have cHRM or gAMA chunks along with sRGB, but the values must
1865
* be consistent with the correct values. If, however, this function is
1866
* called below because an iCCP chunk matches sRGB then it is quite
1867
* conceivable that an older app recorded incorrect gAMA and cHRM because of
1868
* an incorrect calculation based on the values in the profile - this does
1869
* *not* invalidate the profile (though it still produces an error, which can
1872
if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
1873
return png_icc_profile_error(png_ptr, colorspace, "sRGB",
1874
(unsigned)intent, "invalid sRGB rendering intent");
1876
if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
1877
colorspace->rendering_intent != intent)
1878
return png_icc_profile_error(png_ptr, colorspace, "sRGB",
1879
(unsigned)intent, "inconsistent rendering intents");
1881
if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
1883
png_benign_error(png_ptr, "duplicate sRGB information ignored");
1887
/* If the standard sRGB cHRM chunk does not match the one from the PNG file
1888
* warn but overwrite the value with the correct one.
1890
if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 &&
1891
!png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
1893
png_chunk_report(png_ptr, "cHRM chunk does not match sRGB",
1896
/* This check is just done for the error reporting - the routine always
1897
* returns true when the 'from' argument corresponds to sRGB (2).
1899
(void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE,
1902
/* intent: bugs in GCC force 'int' to be used as the parameter type. */
1903
colorspace->rendering_intent = (png_uint_16)intent;
1904
colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT;
1907
colorspace->end_points_xy = sRGB_xy;
1908
colorspace->end_points_XYZ = sRGB_XYZ;
1909
colorspace->flags |=
1910
(PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
1913
colorspace->gamma = PNG_GAMMA_sRGB_INVERSE;
1914
colorspace->flags |= PNG_COLORSPACE_HAVE_GAMMA;
1916
/* Finally record that we have an sRGB profile */
1917
colorspace->flags |=
1918
(PNG_COLORSPACE_MATCHES_sRGB|PNG_COLORSPACE_FROM_sRGB);
1924
#ifdef PNG_iCCP_SUPPORTED
1925
/* Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value
1926
* is XYZ(0.9642,1.0,0.8249), which scales to:
1928
* (63189.8112, 65536, 54060.6464)
1930
static const png_byte D50_nCIEXYZ[12] =
1931
{ 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };
1934
png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
1935
png_const_charp name, png_uint_32 profile_length)
1937
if (profile_length < 132)
1938
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
1945
png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
1946
png_const_charp name, png_uint_32 profile_length,
1947
png_const_bytep profile/* first 132 bytes only */, int color_type)
1951
/* Length check; this cannot be ignored in this code because profile_length
1952
* is used later to check the tag table, so even if the profile seems over
1953
* long profile_length from the caller must be correct. The caller can fix
1954
* this up on read or write by just passing in the profile header length.
1956
temp = png_get_uint_32(profile);
1957
if (temp != profile_length)
1958
return png_icc_profile_error(png_ptr, colorspace, name, temp,
1959
"length does not match profile");
1961
temp = (png_uint_32) (*(profile+8));
1962
if (temp > 3 && (profile_length & 3))
1963
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
1966
temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
1967
if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
1968
profile_length < 132+12*temp) /* truncated tag table */
1969
return png_icc_profile_error(png_ptr, colorspace, name, temp,
1970
"tag count too large");
1972
/* The 'intent' must be valid or we can't store it, ICC limits the intent to
1975
temp = png_get_uint_32(profile+64);
1976
if (temp >= 0xffff) /* The ICC limit */
1977
return png_icc_profile_error(png_ptr, colorspace, name, temp,
1978
"invalid rendering intent");
1980
/* This is just a warning because the profile may be valid in future
1983
if (temp >= PNG_sRGB_INTENT_LAST)
1984
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
1985
"intent outside defined range");
1987
/* At this point the tag table can't be checked because it hasn't necessarily
1988
* been loaded; however, various header fields can be checked. These checks
1989
* are for values permitted by the PNG spec in an ICC profile; the PNG spec
1990
* restricts the profiles that can be passed in an iCCP chunk (they must be
1991
* appropriate to processing PNG data!)
1994
/* Data checks (could be skipped). These checks must be independent of the
1995
* version number; however, the version number doesn't accomodate changes in
1996
* the header fields (just the known tags and the interpretation of the
1999
temp = png_get_uint_32(profile+36); /* signature 'ascp' */
2000
if (temp != 0x61637370)
2001
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2002
"invalid signature");
2004
/* Currently the PCS illuminant/adopted white point (the computational
2005
* white point) are required to be D50,
2006
* however the profile contains a record of the illuminant so perhaps ICC
2007
* expects to be able to change this in the future (despite the rationale in
2008
* the introduction for using a fixed PCS adopted white.) Consequently the
2009
* following is just a warning.
2011
if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
2012
(void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
2013
"PCS illuminant is not D50");
2015
/* The PNG spec requires this:
2016
* "If the iCCP chunk is present, the image samples conform to the colour
2017
* space represented by the embedded ICC profile as defined by the
2018
* International Color Consortium [ICC]. The colour space of the ICC profile
2019
* shall be an RGB colour space for colour images (PNG colour types 2, 3, and
2020
* 6), or a greyscale colour space for greyscale images (PNG colour types 0
2023
* This checking code ensures the embedded profile (on either read or write)
2024
* conforms to the specification requirements. Notice that an ICC 'gray'
2025
* color-space profile contains the information to transform the monochrome
2026
* data to XYZ or L*a*b (according to which PCS the profile uses) and this
2027
* should be used in preference to the standard libpng K channel replication
2028
* into R, G and B channels.
2030
* Previously it was suggested that an RGB profile on grayscale data could be
2031
* handled. However it it is clear that using an RGB profile in this context
2032
* must be an error - there is no specification of what it means. Thus it is
2033
* almost certainly more correct to ignore the profile.
2035
temp = png_get_uint_32(profile+16); /* data colour space field */
2038
case 0x52474220: /* 'RGB ' */
2039
if ((color_type & PNG_COLOR_MASK_COLOR) == 0)
2040
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2041
"RGB color space not permitted on grayscale PNG");
2044
case 0x47524159: /* 'GRAY' */
2045
if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
2046
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2047
"Gray color space not permitted on RGB PNG");
2051
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2052
"invalid ICC profile color space");
2055
/* It is up to the application to check that the profile class matches the
2056
* application requirements; the spec provides no guidance, but it's pretty
2057
* weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer
2058
* ('prtr') or 'spac' (for generic color spaces). Issue a warning in these
2059
* cases. Issue an error for device link or abstract profiles - these don't
2060
* contain the records necessary to transform the color-space to anything
2061
* other than the target device (and not even that for an abstract profile).
2062
* Profiles of these classes may not be embedded in images.
2064
temp = png_get_uint_32(profile+12); /* profile/device class */
2067
case 0x73636e72: /* 'scnr' */
2068
case 0x6d6e7472: /* 'mntr' */
2069
case 0x70727472: /* 'prtr' */
2070
case 0x73706163: /* 'spac' */
2074
case 0x61627374: /* 'abst' */
2075
/* May not be embedded in an image */
2076
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2077
"invalid embedded Abstract ICC profile");
2079
case 0x6c696e6b: /* 'link' */
2080
/* DeviceLink profiles cannot be interpreted in a non-device specific
2081
* fashion, if an app uses the AToB0Tag in the profile the results are
2082
* undefined unless the result is sent to the intended device,
2083
* therefore a DeviceLink profile should not be found embedded in a
2086
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2087
"unexpected DeviceLink ICC profile class");
2089
case 0x6e6d636c: /* 'nmcl' */
2090
/* A NamedColor profile is also device specific, however it doesn't
2091
* contain an AToB0 tag that is open to misinterpretation. Almost
2092
* certainly it will fail the tests below.
2094
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
2095
"unexpected NamedColor ICC profile class");
2099
/* To allow for future enhancements to the profile accept unrecognized
2100
* profile classes with a warning, these then hit the test below on the
2101
* tag content to ensure they are backward compatible with one of the
2102
* understood profiles.
2104
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
2105
"unrecognized ICC profile class");
2109
/* For any profile other than a device link one the PCS must be encoded
2110
* either in XYZ or Lab.
2112
temp = png_get_uint_32(profile+20);
2115
case 0x58595a20: /* 'XYZ ' */
2116
case 0x4c616220: /* 'Lab ' */
2120
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2121
"unexpected ICC PCS encoding");
2128
png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
2129
png_const_charp name, png_uint_32 profile_length,
2130
png_const_bytep profile /* header plus whole tag table */)
2132
png_uint_32 tag_count = png_get_uint_32(profile+128);
2134
png_const_bytep tag = profile+132; /* The first tag */
2136
/* First scan all the tags in the table and add bits to the icc_info value
2137
* (temporarily in 'tags').
2139
for (itag=0; itag < tag_count; ++itag, tag += 12)
2141
png_uint_32 tag_id = png_get_uint_32(tag+0);
2142
png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */
2143
png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */
2145
/* The ICC specification does not exclude zero length tags, therefore the
2146
* start might actually be anywhere if there is no data, but this would be
2147
* a clear abuse of the intent of the standard so the start is checked for
2148
* being in range. All defined tag types have an 8 byte header - a 4 byte
2149
* type signature then 0.
2151
if ((tag_start & 3) != 0)
2153
/* CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is
2154
* only a warning here because libpng does not care about the
2157
(void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
2158
"ICC profile tag start not a multiple of 4");
2161
/* This is a hard error; potentially it can cause read outside the
2164
if (tag_start > profile_length || tag_length > profile_length - tag_start)
2165
return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
2166
"ICC profile tag outside profile");
2169
return 1; /* success, maybe with warnings */
2172
#ifdef PNG_sRGB_SUPPORTED
2173
#if PNG_sRGB_PROFILE_CHECKS >= 0
2174
/* Information about the known ICC sRGB profiles */
2177
png_uint_32 adler, crc, length;
2183
# define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0)
2184
# define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\
2185
{ adler, crc, length, md5, broke, intent },
2187
} png_sRGB_checks[] =
2189
/* This data comes from contrib/tools/checksum-icc run on downloads of
2190
* all four ICC sRGB profiles from www.color.org.
2192
/* adler32, crc32, MD5[4], intent, date, length, file-name */
2193
PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
2194
PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
2195
"2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
2197
/* ICC sRGB v2 perceptual no black-compensation: */
2198
PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21,
2199
PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
2200
"2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")
2202
PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae,
2203
PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
2204
"2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")
2206
/* ICC sRGB v4 perceptual */
2207
PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812,
2208
PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
2209
"2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")
2211
/* The following profiles have no known MD5 checksum. If there is a match
2212
* on the (empty) MD5 the other fields are used to attempt a match and
2213
* a warning is produced. The first two of these profiles have a 'cprt' tag
2214
* which suggests that they were also made by Hewlett Packard.
2216
PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce,
2217
PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
2218
"2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")
2220
/* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not
2221
* match the D50 PCS illuminant in the header (it is in fact the D65 values,
2222
* so the white point is recorded as the un-adapted value.) The profiles
2223
* below only differ in one byte - the intent - and are basically the same as
2224
* the previous profile except for the mediaWhitePointTag error and a missing
2225
* chromaticAdaptationTag.
2227
PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
2228
PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
2229
"1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
2231
PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
2232
PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
2233
"1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
2237
png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
2238
png_const_bytep profile, uLong adler)
2240
/* The quick check is to verify just the MD5 signature and trust the
2241
* rest of the data. Because the profile has already been verified for
2242
* correctness this is safe. png_colorspace_set_sRGB will check the 'intent'
2243
* field too, so if the profile has been edited with an intent not defined
2244
* by sRGB (but maybe defined by a later ICC specification) the read of
2245
* the profile will fail at that point.
2248
png_uint_32 length = 0;
2249
png_uint_32 intent = 0x10000; /* invalid */
2250
#if PNG_sRGB_PROFILE_CHECKS > 1
2251
uLong crc = 0; /* the value for 0 length data */
2255
#ifdef PNG_SET_OPTION_SUPPORTED
2256
/* First see if PNG_SKIP_sRGB_CHECK_PROFILE has been set to "on" */
2257
if (((png_ptr->options >> PNG_SKIP_sRGB_CHECK_PROFILE) & 3) ==
2262
for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i)
2264
if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] &&
2265
png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] &&
2266
png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] &&
2267
png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3])
2269
/* This may be one of the old HP profiles without an MD5, in that
2270
* case we can only use the length and Adler32 (note that these
2271
* are not used by default if there is an MD5!)
2273
# if PNG_sRGB_PROFILE_CHECKS == 0
2274
if (png_sRGB_checks[i].have_md5 != 0)
2275
return 1+png_sRGB_checks[i].is_broken;
2278
/* Profile is unsigned or more checks have been configured in. */
2281
length = png_get_uint_32(profile);
2282
intent = png_get_uint_32(profile+64);
2285
/* Length *and* intent must match */
2286
if (length == (png_uint_32) png_sRGB_checks[i].length &&
2287
intent == (png_uint_32) png_sRGB_checks[i].intent)
2289
/* Now calculate the adler32 if not done already. */
2292
adler = adler32(0, NULL, 0);
2293
adler = adler32(adler, profile, length);
2296
if (adler == png_sRGB_checks[i].adler)
2298
/* These basic checks suggest that the data has not been
2299
* modified, but if the check level is more than 1 perform
2300
* our own crc32 checksum on the data.
2302
# if PNG_sRGB_PROFILE_CHECKS > 1
2305
crc = crc32(0, NULL, 0);
2306
crc = crc32(crc, profile, length);
2309
/* So this check must pass for the 'return' below to happen.
2311
if (crc == png_sRGB_checks[i].crc)
2314
if (png_sRGB_checks[i].is_broken != 0)
2316
/* These profiles are known to have bad data that may cause
2317
* problems if they are used, therefore attempt to
2318
* discourage their use, skip the 'have_md5' warning below,
2319
* which is made irrelevant by this error.
2321
png_chunk_report(png_ptr, "known incorrect sRGB profile",
2325
/* Warn that this being done; this isn't even an error since
2326
* the profile is perfectly valid, but it would be nice if
2327
* people used the up-to-date ones.
2329
else if (png_sRGB_checks[i].have_md5 == 0)
2331
png_chunk_report(png_ptr,
2332
"out-of-date sRGB profile with no signature",
2336
return 1+png_sRGB_checks[i].is_broken;
2340
# if PNG_sRGB_PROFILE_CHECKS > 0
2341
/* The signature matched, but the profile had been changed in some
2342
* way. This probably indicates a data error or uninformed hacking.
2343
* Fall through to "no match".
2345
png_chunk_report(png_ptr,
2346
"Not recognizing known sRGB profile that has been edited",
2354
return 0; /* no match */
2356
#endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */
2359
png_icc_set_sRGB(png_const_structrp png_ptr,
2360
png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
2362
/* Is this profile one of the known ICC sRGB profiles? If it is, just set
2363
* the sRGB information.
2365
#if PNG_sRGB_PROFILE_CHECKS >= 0
2366
if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
2368
(void)png_colorspace_set_sRGB(png_ptr, colorspace,
2369
(int)/*already checked*/png_get_uint_32(profile+64));
2374
png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
2375
png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
2378
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
2381
if (png_icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
2382
png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
2384
png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
2387
# ifdef PNG_sRGB_SUPPORTED
2388
/* If no sRGB support, don't try storing sRGB information */
2389
png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
2399
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2401
png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
2403
/* Set the rgb_to_gray coefficients from the colorspace. */
2404
if (png_ptr->rgb_to_gray_coefficients_set == 0 &&
2405
(png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
2407
/* png_set_background has not been called, get the coefficients from the Y
2408
* values of the colorspace colorants.
2410
png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
2411
png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
2412
png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
2413
png_fixed_point total = r+g+b;
2416
r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
2417
g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
2418
b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
2421
/* We allow 0 coefficients here. r+g+b may be 32769 if two or
2422
* all of the coefficients were rounded up. Handle this by
2423
* reducing the *largest* coefficient by 1; this matches the
2424
* approach used for the default coefficients in pngrtran.c
2430
else if (r+g+b < 32768)
2435
if (g >= r && g >= b)
2437
else if (r >= g && r >= b)
2443
/* Check for an internal error. */
2446
"internal error handling cHRM coefficients");
2450
png_ptr->rgb_to_gray_red_coeff = (png_uint_16)r;
2451
png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
2455
/* This is a png_error at present even though it could be ignored -
2456
* it should never happen, but it is important that if it does, the
2460
png_error(png_ptr, "internal error handling cHRM->XYZ");
2463
#endif /* READ_RGB_TO_GRAY */
2465
#endif /* COLORSPACE */
2468
/* This exists solely to work round a warning from GNU C. */
2469
static int /* PRIVATE */
2470
png_gt(size_t a, size_t b)
2475
# define png_gt(a,b) ((a) > (b))
2479
png_check_IHDR(png_const_structrp png_ptr,
2480
png_uint_32 width, png_uint_32 height, int bit_depth,
2481
int color_type, int interlace_type, int compression_type,
2486
/* Check for width and height valid values */
2489
png_warning(png_ptr, "Image width is zero in IHDR");
2493
if (width > PNG_UINT_31_MAX)
2495
png_warning(png_ptr, "Invalid image width in IHDR");
2499
if (png_gt(((width + 7) & (~7)),
2501
- 48 /* big_row_buf hack */
2502
- 1) /* filter byte */
2503
/ 8) /* 8-byte RGBA pixels */
2504
- 1)) /* extra max_pixel_depth pad */
2506
/* The size of the row must be within the limits of this architecture.
2507
* Because the read code can perform arbitrary transformations the
2508
* maximum size is checked here. Because the code in png_read_start_row
2509
* adds extra space "for safety's sake" in several places a conservative
2510
* limit is used here.
2512
* NOTE: it would be far better to check the size that is actually used,
2513
* but the effect in the real world is minor and the changes are more
2514
* extensive, therefore much more dangerous and much more difficult to
2515
* write in a way that avoids compiler warnings.
2517
png_warning(png_ptr, "Image width is too large for this architecture");
2521
#ifdef PNG_SET_USER_LIMITS_SUPPORTED
2522
if (width > png_ptr->user_width_max)
2524
if (width > PNG_USER_WIDTH_MAX)
2527
png_warning(png_ptr, "Image width exceeds user limit in IHDR");
2533
png_warning(png_ptr, "Image height is zero in IHDR");
2537
if (height > PNG_UINT_31_MAX)
2539
png_warning(png_ptr, "Invalid image height in IHDR");
2543
#ifdef PNG_SET_USER_LIMITS_SUPPORTED
2544
if (height > png_ptr->user_height_max)
2546
if (height > PNG_USER_HEIGHT_MAX)
2549
png_warning(png_ptr, "Image height exceeds user limit in IHDR");
2553
/* Check other values */
2554
if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
2555
bit_depth != 8 && bit_depth != 16)
2557
png_warning(png_ptr, "Invalid bit depth in IHDR");
2561
if (color_type < 0 || color_type == 1 ||
2562
color_type == 5 || color_type > 6)
2564
png_warning(png_ptr, "Invalid color type in IHDR");
2568
if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
2569
((color_type == PNG_COLOR_TYPE_RGB ||
2570
color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
2571
color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
2573
png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR");
2577
if (interlace_type >= PNG_INTERLACE_LAST)
2579
png_warning(png_ptr, "Unknown interlace method in IHDR");
2583
if (compression_type != PNG_COMPRESSION_TYPE_BASE)
2585
png_warning(png_ptr, "Unknown compression method in IHDR");
2589
#ifdef PNG_MNG_FEATURES_SUPPORTED
2590
/* Accept filter_method 64 (intrapixel differencing) only if
2591
* 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
2592
* 2. Libpng did not read a PNG signature (this filter_method is only
2593
* used in PNG datastreams that are embedded in MNG datastreams) and
2594
* 3. The application called png_permit_mng_features with a mask that
2595
* included PNG_FLAG_MNG_FILTER_64 and
2596
* 4. The filter_method is 64 and
2597
* 5. The color_type is RGB or RGBA
2599
if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 &&
2600
png_ptr->mng_features_permitted != 0)
2601
png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
2603
if (filter_type != PNG_FILTER_TYPE_BASE)
2605
if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
2606
(filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
2607
((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
2608
(color_type == PNG_COLOR_TYPE_RGB ||
2609
color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
2611
png_warning(png_ptr, "Unknown filter method in IHDR");
2615
if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0)
2617
png_warning(png_ptr, "Invalid filter method in IHDR");
2623
if (filter_type != PNG_FILTER_TYPE_BASE)
2625
png_warning(png_ptr, "Unknown filter method in IHDR");
2631
png_error(png_ptr, "Invalid IHDR data");
2634
#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
2635
/* ASCII to fp functions */
2636
/* Check an ASCII formated floating point value, see the more detailed
2637
* comments in pngpriv.h
2639
/* The following is used internally to preserve the sticky flags */
2640
#define png_fp_add(state, flags) ((state) |= (flags))
2641
#define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY))
2644
png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
2645
png_size_tp whereami)
2647
int state = *statep;
2648
png_size_t i = *whereami;
2653
/* First find the type of the next character */
2656
case 43: type = PNG_FP_SAW_SIGN; break;
2657
case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break;
2658
case 46: type = PNG_FP_SAW_DOT; break;
2659
case 48: type = PNG_FP_SAW_DIGIT; break;
2660
case 49: case 50: case 51: case 52:
2661
case 53: case 54: case 55: case 56:
2662
case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break;
2664
case 101: type = PNG_FP_SAW_E; break;
2665
default: goto PNG_FP_End;
2668
/* Now deal with this type according to the current
2669
* state, the type is arranged to not overlap the
2670
* bits of the PNG_FP_STATE.
2672
switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
2674
case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
2675
if ((state & PNG_FP_SAW_ANY) != 0)
2676
goto PNG_FP_End; /* not a part of the number */
2678
png_fp_add(state, type);
2681
case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
2682
/* Ok as trailer, ok as lead of fraction. */
2683
if ((state & PNG_FP_SAW_DOT) != 0) /* two dots */
2686
else if ((state & PNG_FP_SAW_DIGIT) != 0) /* trailing dot? */
2687
png_fp_add(state, type);
2690
png_fp_set(state, PNG_FP_FRACTION | type);
2694
case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
2695
if ((state & PNG_FP_SAW_DOT) != 0) /* delayed fraction */
2696
png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);
2698
png_fp_add(state, type | PNG_FP_WAS_VALID);
2702
case PNG_FP_INTEGER + PNG_FP_SAW_E:
2703
if ((state & PNG_FP_SAW_DIGIT) == 0)
2706
png_fp_set(state, PNG_FP_EXPONENT);
2710
/* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN:
2711
goto PNG_FP_End; ** no sign in fraction */
2713
/* case PNG_FP_FRACTION + PNG_FP_SAW_DOT:
2714
goto PNG_FP_End; ** Because SAW_DOT is always set */
2716
case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT:
2717
png_fp_add(state, type | PNG_FP_WAS_VALID);
2720
case PNG_FP_FRACTION + PNG_FP_SAW_E:
2721
/* This is correct because the trailing '.' on an
2722
* integer is handled above - so we can only get here
2723
* with the sequence ".E" (with no preceding digits).
2725
if ((state & PNG_FP_SAW_DIGIT) == 0)
2728
png_fp_set(state, PNG_FP_EXPONENT);
2732
case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
2733
if ((state & PNG_FP_SAW_ANY) != 0)
2734
goto PNG_FP_End; /* not a part of the number */
2736
png_fp_add(state, PNG_FP_SAW_SIGN);
2740
/* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT:
2743
case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT:
2744
png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID);
2748
/* case PNG_FP_EXPONEXT + PNG_FP_SAW_E:
2751
default: goto PNG_FP_End; /* I.e. break 2 */
2754
/* The character seems ok, continue. */
2759
/* Here at the end, update the state and return the correct
2765
return (state & PNG_FP_SAW_DIGIT) != 0;
2769
/* The same but for a complete string. */
2771
png_check_fp_string(png_const_charp string, png_size_t size)
2774
png_size_t char_index=0;
2776
if (png_check_fp_number(string, size, &state, &char_index) != 0 &&
2777
(char_index == size || string[char_index] == 0))
2778
return state /* must be non-zero - see above */;
2780
return 0; /* i.e. fail */
2782
#endif /* pCAL || sCAL */
2784
#ifdef PNG_sCAL_SUPPORTED
2785
# ifdef PNG_FLOATING_POINT_SUPPORTED
2786
/* Utility used below - a simple accurate power of ten from an integral
2790
png_pow10(int power)
2795
/* Handle negative exponent with a reciprocal at the end because
2796
* 10 is exact whereas .1 is inexact in base 2
2800
if (power < DBL_MIN_10_EXP) return 0;
2801
recip = 1, power = -power;
2806
/* Decompose power bitwise. */
2810
if (power & 1) d *= mult;
2816
if (recip != 0) d = 1/d;
2818
/* else power is 0 and d is 1 */
2823
/* Function to format a floating point value in ASCII with a given
2827
png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
2828
double fp, unsigned int precision)
2830
/* We use standard functions from math.h, but not printf because
2831
* that would require stdio. The caller must supply a buffer of
2832
* sufficient size or we will png_error. The tests on size and
2833
* the space in ascii[] consumed are indicated below.
2836
precision = DBL_DIG;
2838
/* Enforce the limit of the implementation precision too. */
2839
if (precision > DBL_DIG+1)
2840
precision = DBL_DIG+1;
2842
/* Basic sanity checks */
2843
if (size >= precision+5) /* See the requirements below. */
2848
*ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */
2852
if (fp >= DBL_MIN && fp <= DBL_MAX)
2854
int exp_b10; /* A base 10 exponent */
2855
double base; /* 10^exp_b10 */
2857
/* First extract a base 10 exponent of the number,
2858
* the calculation below rounds down when converting
2859
* from base 2 to base 10 (multiply by log10(2) -
2860
* 0.3010, but 77/256 is 0.3008, so exp_b10 needs to
2861
* be increased. Note that the arithmetic shift
2862
* performs a floor() unlike C arithmetic - using a
2863
* C multiply would break the following for negative
2866
(void)frexp(fp, &exp_b10); /* exponent to base 2 */
2868
exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */
2870
/* Avoid underflow here. */
2871
base = png_pow10(exp_b10); /* May underflow */
2873
while (base < DBL_MIN || base < fp)
2875
/* And this may overflow. */
2876
double test = png_pow10(exp_b10+1);
2878
if (test <= DBL_MAX)
2879
++exp_b10, base = test;
2885
/* Normalize fp and correct exp_b10, after this fp is in the
2886
* range [.1,1) and exp_b10 is both the exponent and the digit
2887
* *before* which the decimal point should be inserted
2888
* (starting with 0 for the first digit). Note that this
2889
* works even if 10^exp_b10 is out of range because of the
2890
* test on DBL_MAX above.
2893
while (fp >= 1) fp /= 10, ++exp_b10;
2895
/* Because of the code above fp may, at this point, be
2896
* less than .1, this is ok because the code below can
2897
* handle the leading zeros this generates, so no attempt
2898
* is made to correct that here.
2902
unsigned int czero, clead, cdigits;
2905
/* Allow up to two leading zeros - this will not lengthen
2906
* the number compared to using E-n.
2908
if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */
2910
czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */
2911
exp_b10 = 0; /* Dot added below before first output. */
2914
czero = 0; /* No zeros to add */
2916
/* Generate the digit list, stripping trailing zeros and
2917
* inserting a '.' before a digit if the exponent is 0.
2919
clead = czero; /* Count of leading zeros */
2920
cdigits = 0; /* Count of digits in list. */
2927
/* Use modf here, not floor and subtract, so that
2928
* the separation is done in one step. At the end
2929
* of the loop don't break the number into parts so
2930
* that the final digit is rounded.
2932
if (cdigits+czero+1 < precision+clead)
2941
/* Rounding up to 10, handle that here. */
2945
if (cdigits == 0) --clead;
2949
while (cdigits > 0 && d > 9)
2953
if (exp_b10 != (-1))
2958
ch = *--ascii, ++size;
2959
/* Advance exp_b10 to '1', so that the
2960
* decimal point happens after the
2967
d = ch - 47; /* I.e. 1+(ch-48) */
2970
/* Did we reach the beginning? If so adjust the
2971
* exponent but take into account the leading
2974
if (d > 9) /* cdigits == 0 */
2976
if (exp_b10 == (-1))
2978
/* Leading decimal point (plus zeros?), if
2979
* we lose the decimal point here it must
2980
* be reentered below.
2985
++size, exp_b10 = 1;
2987
/* Else lost a leading zero, so 'exp_b10' is
2994
/* In all cases we output a '1' */
2999
fp = 0; /* Guarantees termination below. */
3005
if (cdigits == 0) ++clead;
3009
/* Included embedded zeros in the digit count. */
3010
cdigits += czero - clead;
3015
/* exp_b10 == (-1) means we just output the decimal
3016
* place - after the DP don't adjust 'exp_b10' any
3019
if (exp_b10 != (-1))
3021
if (exp_b10 == 0) *ascii++ = 46, --size;
3022
/* PLUS 1: TOTAL 4 */
3025
*ascii++ = 48, --czero;
3028
if (exp_b10 != (-1))
3031
*ascii++ = 46, --size; /* counted above */
3035
*ascii++ = (char)(48 + (int)d), ++cdigits;
3038
while (cdigits+czero < precision+clead && fp > DBL_MIN);
3040
/* The total output count (max) is now 4+precision */
3042
/* Check for an exponent, if we don't need one we are
3043
* done and just need to terminate the string. At
3044
* this point exp_b10==(-1) is effectively if flag - it got
3045
* to '-1' because of the decrement after outputting
3046
* the decimal point above (the exponent required is
3049
if (exp_b10 >= (-1) && exp_b10 <= 2)
3051
/* The following only happens if we didn't output the
3052
* leading zeros above for negative exponent, so this
3053
* doesn't add to the digit requirement. Note that the
3054
* two zeros here can only be output if the two leading
3055
* zeros were *not* output, so this doesn't increase
3058
while (--exp_b10 >= 0) *ascii++ = 48;
3062
/* Total buffer requirement (including the '\0') is
3063
* 5+precision - see check at the start.
3068
/* Here if an exponent is required, adjust size for
3069
* the digits we output but did not count. The total
3070
* digit output here so far is at most 1+precision - no
3071
* decimal point and no leading or trailing zeros have
3076
*ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision */
3078
/* The following use of an unsigned temporary avoids ambiguities in
3079
* the signed arithmetic on exp_b10 and permits GCC at least to do
3080
* better optimization.
3083
unsigned int uexp_b10;
3087
*ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */
3088
uexp_b10 = -exp_b10;
3096
while (uexp_b10 > 0)
3098
exponent[cdigits++] = (char)(48 + uexp_b10 % 10);
3103
/* Need another size check here for the exponent digits, so
3104
* this need not be considered above.
3108
while (cdigits > 0) *ascii++ = exponent[--cdigits];
3116
else if (!(fp >= DBL_MIN))
3118
*ascii++ = 48; /* '0' */
3124
*ascii++ = 105; /* 'i' */
3125
*ascii++ = 110; /* 'n' */
3126
*ascii++ = 102; /* 'f' */
3132
/* Here on buffer too small. */
3133
png_error(png_ptr, "ASCII conversion buffer too small");
3136
# endif /* FLOATING_POINT */
3138
# ifdef PNG_FIXED_POINT_SUPPORTED
3139
/* Function to format a fixed point value in ASCII.
3142
png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
3143
png_size_t size, png_fixed_point fp)
3145
/* Require space for 10 decimal digits, a decimal point, a minus sign and a
3146
* trailing \0, 13 characters:
3152
/* Avoid overflow here on the minimum integer. */
3154
*ascii++ = 45, num = -fp;
3158
if (num <= 0x80000000) /* else overflowed */
3160
unsigned int ndigits = 0, first = 16 /* flag value */;
3165
/* Split the low digit off num: */
3166
unsigned int tmp = num/10;
3168
digits[ndigits++] = (char)(48 + num);
3169
/* Record the first non-zero digit, note that this is a number
3170
* starting at 1, it's not actually the array index.
3172
if (first == 16 && num > 0)
3179
while (ndigits > 5) *ascii++ = digits[--ndigits];
3180
/* The remaining digits are fractional digits, ndigits is '5' or
3181
* smaller at this point. It is certainly not zero. Check for a
3182
* non-zero fractional digit:
3187
*ascii++ = 46; /* decimal point */
3188
/* ndigits may be <5 for small numbers, output leading zeros
3189
* then ndigits digits to first:
3192
while (ndigits < i) *ascii++ = 48, --i;
3193
while (ndigits >= first) *ascii++ = digits[--ndigits];
3194
/* Don't output the trailing zeros! */
3200
/* And null terminate the string: */
3206
/* Here on buffer too small. */
3207
png_error(png_ptr, "ASCII conversion buffer too small");
3209
# endif /* FIXED_POINT */
3212
#if defined(PNG_FLOATING_POINT_SUPPORTED) && \
3213
!defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
3214
(defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
3215
defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
3216
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
3217
(defined(PNG_sCAL_SUPPORTED) && \
3218
defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
3220
png_fixed(png_const_structrp png_ptr, double fp, png_const_charp text)
3222
double r = floor(100000 * fp + .5);
3224
if (r > 2147483647. || r < -2147483648.)
3225
png_fixed_error(png_ptr, text);
3227
# ifndef PNG_ERROR_TEXT_SUPPORTED
3231
return (png_fixed_point)r;
3235
#if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_COLORSPACE_SUPPORTED) ||\
3236
defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
3237
/* muldiv functions */
3238
/* This API takes signed arguments and rounds the result to the nearest
3239
* integer (or, for a fixed point number - the standard argument - to
3240
* the nearest .00001). Overflow and divide by zero are signalled in
3241
* the result, a boolean - true on success, false on overflow.
3244
png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
3247
/* Return a * times / divisor, rounded. */
3250
if (a == 0 || times == 0)
3257
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3263
/* A png_fixed_point is a 32-bit integer. */
3264
if (r <= 2147483647. && r >= -2147483648.)
3266
*res = (png_fixed_point)r;
3271
png_uint_32 A, T, D;
3272
png_uint_32 s16, s32, s00;
3275
negative = 1, A = -a;
3280
negative = !negative, T = -times;
3285
negative = !negative, D = -divisor;
3289
/* Following can't overflow because the arguments only
3290
* have 31 bits each, however the result may be 32 bits.
3292
s16 = (A >> 16) * (T & 0xffff) +
3293
(A & 0xffff) * (T >> 16);
3294
/* Can't overflow because the a*times bit is only 30
3297
s32 = (A >> 16) * (T >> 16) + (s16 >> 16);
3298
s00 = (A & 0xffff) * (T & 0xffff);
3300
s16 = (s16 & 0xffff) << 16;
3306
if (s32 < D) /* else overflow */
3308
/* s32.s00 is now the 64-bit product, do a standard
3309
* division, we know that s32 < D, so the maximum
3310
* required shift is 31.
3313
png_fixed_point result = 0; /* NOTE: signed */
3315
while (--bitshift >= 0)
3317
png_uint_32 d32, d00;
3320
d32 = D >> (32-bitshift), d00 = D << bitshift;
3327
if (s00 < d00) --s32; /* carry */
3328
s32 -= d32, s00 -= d00, result += 1<<bitshift;
3332
if (s32 == d32 && s00 >= d00)
3333
s32 = 0, s00 -= d00, result += 1<<bitshift;
3336
/* Handle the rounding. */
3337
if (s00 >= (D >> 1))
3343
/* Check for overflow. */
3344
if ((negative != 0 && result <= 0) ||
3345
(negative == 0 && result >= 0))
3357
#endif /* READ_GAMMA || INCH_CONVERSIONS */
3359
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
3360
/* The following is for when the caller doesn't much care about the
3364
png_muldiv_warn(png_const_structrp png_ptr, png_fixed_point a, png_int_32 times,
3367
png_fixed_point result;
3369
if (png_muldiv(&result, a, times, divisor) != 0)
3372
png_warning(png_ptr, "fixed point overflow ignored");
3377
#ifdef PNG_GAMMA_SUPPORTED /* more fixed point functions for gamma */
3378
/* Calculate a reciprocal, return 0 on div-by-zero or overflow. */
3380
png_reciprocal(png_fixed_point a)
3382
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3383
double r = floor(1E10/a+.5);
3385
if (r <= 2147483647. && r >= -2147483648.)
3386
return (png_fixed_point)r;
3388
png_fixed_point res;
3390
if (png_muldiv(&res, 100000, 100000, a) != 0)
3394
return 0; /* error/overflow */
3397
/* This is the shared test on whether a gamma value is 'significant' - whether
3398
* it is worth doing gamma correction.
3401
png_gamma_significant(png_fixed_point gamma_val)
3403
return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
3404
gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
3408
#ifdef PNG_READ_GAMMA_SUPPORTED
3409
#ifdef PNG_16BIT_SUPPORTED
3410
/* A local convenience routine. */
3411
static png_fixed_point
3412
png_product2(png_fixed_point a, png_fixed_point b)
3414
/* The required result is 1/a * 1/b; the following preserves accuracy. */
3415
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3416
double r = a * 1E-5;
3420
if (r <= 2147483647. && r >= -2147483648.)
3421
return (png_fixed_point)r;
3423
png_fixed_point res;
3425
if (png_muldiv(&res, a, b, 100000) != 0)
3429
return 0; /* overflow */
3433
/* The inverse of the above. */
3435
png_reciprocal2(png_fixed_point a, png_fixed_point b)
3437
/* The required result is 1/a * 1/b; the following preserves accuracy. */
3438
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3439
if (a != 0 && b != 0)
3445
if (r <= 2147483647. && r >= -2147483648.)
3446
return (png_fixed_point)r;
3449
/* This may overflow because the range of png_fixed_point isn't symmetric,
3450
* but this API is only used for the product of file and screen gamma so it
3451
* doesn't matter that the smallest number it can produce is 1/21474, not
3454
png_fixed_point res = png_product2(a, b);
3457
return png_reciprocal(res);
3460
return 0; /* overflow */
3462
#endif /* READ_GAMMA */
3464
#ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */
3465
#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
3466
/* Fixed point gamma.
3468
* The code to calculate the tables used below can be found in the shell script
3469
* contrib/tools/intgamma.sh
3471
* To calculate gamma this code implements fast log() and exp() calls using only
3472
* fixed point arithmetic. This code has sufficient precision for either 8-bit
3473
* or 16-bit sample values.
3475
* The tables used here were calculated using simple 'bc' programs, but C double
3476
* precision floating point arithmetic would work fine.
3479
* This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
3480
* 255, so it's the base 2 logarithm of a normalized 8-bit floating point
3481
* mantissa. The numbers are 32-bit fractions.
3483
static const png_uint_32
3486
4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U,
3487
3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U,
3488
3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U,
3489
3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U,
3490
3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U,
3491
2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U,
3492
2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U,
3493
2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U,
3494
2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U,
3495
2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U,
3496
1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U,
3497
1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U,
3498
1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U,
3499
1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U,
3500
1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U,
3501
971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U,
3502
803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U,
3503
639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U,
3504
479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U,
3505
324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U,
3506
172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U,
3510
/* The following are the values for 16-bit tables - these work fine for the
3511
* 8-bit conversions but produce very slightly larger errors in the 16-bit
3512
* log (about 1.2 as opposed to 0.7 absolute error in the final value). To
3513
* use these all the shifts below must be adjusted appropriately.
3515
65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054,
3516
57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803,
3517
50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068,
3518
43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782,
3519
37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887,
3520
31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339,
3521
25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098,
3522
20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132,
3523
15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415,
3524
10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523,
3525
6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495,
3531
png_log8bit(unsigned int x)
3533
unsigned int lg2 = 0;
3534
/* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log,
3535
* because the log is actually negate that means adding 1. The final
3536
* returned value thus has the range 0 (for 255 input) to 7.994 (for 1
3537
* input), return -1 for the overflow (log 0) case, - so the result is
3538
* always at most 19 bits.
3540
if ((x &= 0xff) == 0)
3543
if ((x & 0xf0) == 0)
3546
if ((x & 0xc0) == 0)
3549
if ((x & 0x80) == 0)
3552
/* result is at most 19 bits, so this cast is safe: */
3553
return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16));
3556
/* The above gives exact (to 16 binary places) log2 values for 8-bit images,
3557
* for 16-bit images we use the most significant 8 bits of the 16-bit value to
3558
* get an approximation then multiply the approximation by a correction factor
3559
* determined by the remaining up to 8 bits. This requires an additional step
3560
* in the 16-bit case.
3562
* We want log2(value/65535), we have log2(v'/255), where:
3564
* value = v' * 256 + v''
3567
* So f is value/v', which is equal to (256+v''/v') since v' is in the range 128
3568
* to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less
3569
* than 258. The final factor also needs to correct for the fact that our 8-bit
3570
* value is scaled by 255, whereas the 16-bit values must be scaled by 65535.
3572
* This gives a final formula using a calculated value 'x' which is value/v' and
3573
* scaling by 65536 to match the above table:
3575
* log2(x/257) * 65536
3577
* Since these numbers are so close to '1' we can use simple linear
3578
* interpolation between the two end values 256/257 (result -368.61) and 258/257
3579
* (result 367.179). The values used below are scaled by a further 64 to give
3580
* 16-bit precision in the interpolation:
3582
* Start (256): -23591
3586
#ifdef PNG_16BIT_SUPPORTED
3588
png_log16bit(png_uint_32 x)
3590
unsigned int lg2 = 0;
3592
/* As above, but now the input has 16 bits. */
3593
if ((x &= 0xffff) == 0)
3596
if ((x & 0xff00) == 0)
3599
if ((x & 0xf000) == 0)
3602
if ((x & 0xc000) == 0)
3605
if ((x & 0x8000) == 0)
3608
/* Calculate the base logarithm from the top 8 bits as a 28-bit fractional
3612
lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4;
3614
/* Now we need to interpolate the factor, this requires a division by the top
3615
* 8 bits. Do this with maximum precision.
3617
x = ((x << 16) + (x >> 9)) / (x >> 8);
3619
/* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24,
3620
* the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly
3621
* 16 bits to interpolate to get the low bits of the result. Round the
3622
* answer. Note that the end point values are scaled by 64 to retain overall
3623
* precision and that 'lg2' is current scaled by an extra 12 bits, so adjust
3624
* the overall scaling by 6-12. Round at every step.
3628
if (x <= 65536U) /* <= '257' */
3629
lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12);
3632
lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12);
3634
/* Safe, because the result can't have more than 20 bits: */
3635
return (png_int_32)((lg2 + 2048) >> 12);
3639
/* The 'exp()' case must invert the above, taking a 20-bit fixed point
3640
* logarithmic value and returning a 16 or 8-bit number as appropriate. In
3641
* each case only the low 16 bits are relevant - the fraction - since the
3642
* integer bits (the top 4) simply determine a shift.
3644
* The worst case is the 16-bit distinction between 65535 and 65534. This
3645
* requires perhaps spurious accuracy in the decoding of the logarithm to
3646
* distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
3647
* of getting this accuracy in practice.
3649
* To deal with this the following exp() function works out the exponent of the
3650
* frational part of the logarithm by using an accurate 32-bit value from the
3651
* top four fractional bits then multiplying in the remaining bits.
3653
static const png_uint_32
3656
/* NOTE: the first entry is deliberately set to the maximum 32-bit value. */
3657
4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U,
3658
3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U,
3659
2553802834U, 2445529972U, 2341847524U, 2242560872U
3662
/* Adjustment table; provided to explain the numbers in the code below. */
3664
for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}
3665
11 44937.64284865548751208448
3666
10 45180.98734845585101160448
3667
9 45303.31936980687359311872
3668
8 45364.65110595323018870784
3669
7 45395.35850361789624614912
3670
6 45410.72259715102037508096
3671
5 45418.40724413220722311168
3672
4 45422.25021786898173001728
3673
3 45424.17186732298419044352
3674
2 45425.13273269940811464704
3675
1 45425.61317555035558641664
3676
0 45425.85339951654943850496
3680
png_exp(png_fixed_point x)
3682
if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
3684
/* Obtain a 4-bit approximation */
3685
png_uint_32 e = png_32bit_exp[(x >> 12) & 0x0f];
3687
/* Incorporate the low 12 bits - these decrease the returned value by
3688
* multiplying by a number less than 1 if the bit is set. The multiplier
3689
* is determined by the above table and the shift. Notice that the values
3690
* converge on 45426 and this is used to allow linear interpolation of the
3694
e -= (((e >> 16) * 44938U) + 16U) >> 5;
3697
e -= (((e >> 16) * 45181U) + 32U) >> 6;
3700
e -= (((e >> 16) * 45303U) + 64U) >> 7;
3703
e -= (((e >> 16) * 45365U) + 128U) >> 8;
3706
e -= (((e >> 16) * 45395U) + 256U) >> 9;
3709
e -= (((e >> 16) * 45410U) + 512U) >> 10;
3711
/* And handle the low 6 bits in a single block. */
3712
e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9;
3714
/* Handle the upper bits of x. */
3719
/* Check for overflow */
3721
return png_32bit_exp[0];
3723
/* Else underflow */
3728
png_exp8bit(png_fixed_point lg2)
3730
/* Get a 32-bit value: */
3731
png_uint_32 x = png_exp(lg2);
3733
/* Convert the 32-bit value to 0..255 by multiplying by 256-1. Note that the
3734
* second, rounding, step can't overflow because of the first, subtraction,
3738
return (png_byte)(((x + 0x7fffffU) >> 24) & 0xff);
3741
#ifdef PNG_16BIT_SUPPORTED
3743
png_exp16bit(png_fixed_point lg2)
3745
/* Get a 32-bit value: */
3746
png_uint_32 x = png_exp(lg2);
3748
/* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */
3750
return (png_uint_16)((x + 32767U) >> 16);
3753
#endif /* FLOATING_ARITHMETIC */
3756
png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
3758
if (value > 0 && value < 255)
3760
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3761
/* 'value' is unsigned, ANSI-C90 requires the compiler to correctly
3762
* convert this to a floating point value. This includes values that
3763
* would overflow if 'value' were to be converted to 'int'.
3765
* Apparently GCC, however, does an intermediate conversion to (int)
3766
* on some (ARM) but not all (x86) platforms, possibly because of
3767
* hardware FP limitations. (E.g. if the hardware conversion always
3768
* assumes the integer register contains a signed value.) This results
3769
* in ANSI-C undefined behavior for large values.
3771
* Other implementations on the same machine might actually be ANSI-C90
3772
* conformant and therefore compile spurious extra code for the large
3775
* We can be reasonably sure that an unsigned to float conversion
3776
* won't be faster than an int to float one. Therefore this code
3777
* assumes responsibility for the undefined behavior, which it knows
3778
* can't happen because of the check above.
3780
* Note the argument to this routine is an (unsigned int) because, on
3781
* 16-bit platforms, it is assigned a value which might be out of
3782
* range for an (int); that would result in undefined behavior in the
3783
* caller if the *argument* ('value') were to be declared (int).
3785
double r = floor(255*pow((int)/*SAFE*/value/255.,gamma_val*.00001)+.5);
3788
png_int_32 lg2 = png_log8bit(value);
3789
png_fixed_point res;
3791
if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
3792
return png_exp8bit(res);
3799
return (png_byte)(value & 0xff);
3802
#ifdef PNG_16BIT_SUPPORTED
3804
png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
3806
if (value > 0 && value < 65535)
3808
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3809
/* The same (unsigned int)->(double) constraints apply here as above,
3810
* however in this case the (unsigned int) to (int) conversion can
3811
* overflow on an ANSI-C90 compliant system so the cast needs to ensure
3812
* that this is not possible.
3814
double r = floor(65535*pow((png_int_32)value/65535.,
3815
gamma_val*.00001)+.5);
3816
return (png_uint_16)r;
3818
png_int_32 lg2 = png_log16bit(value);
3819
png_fixed_point res;
3821
if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
3822
return png_exp16bit(res);
3829
return (png_uint_16)value;
3833
/* This does the right thing based on the bit_depth field of the
3834
* png_struct, interpreting values as 8-bit or 16-bit. While the result
3835
* is nominally a 16-bit value if bit depth is 8 then the result is
3836
* 8-bit (as are the arguments.)
3838
png_uint_16 /* PRIVATE */
3839
png_gamma_correct(png_structrp png_ptr, unsigned int value,
3840
png_fixed_point gamma_val)
3842
if (png_ptr->bit_depth == 8)
3843
return png_gamma_8bit_correct(value, gamma_val);
3845
#ifdef PNG_16BIT_SUPPORTED
3847
return png_gamma_16bit_correct(value, gamma_val);
3849
/* should not reach this */
3854
#ifdef PNG_16BIT_SUPPORTED
3855
/* Internal function to build a single 16-bit table - the table consists of
3856
* 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount
3857
* to shift the input values right (or 16-number_of_signifiant_bits).
3859
* The caller is responsible for ensuring that the table gets cleaned up on
3860
* png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument
3861
* should be somewhere that will be cleaned.
3864
png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
3865
PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
3867
/* Various values derived from 'shift': */
3868
PNG_CONST unsigned int num = 1U << (8U - shift);
3869
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3870
/* CSE the division and work round wacky GCC warnings (see the comments
3871
* in png_gamma_8bit_correct for where these come from.)
3873
PNG_CONST double fmax = 1./(((png_int_32)1 << (16U - shift))-1);
3875
PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
3876
PNG_CONST unsigned int max_by_2 = 1U << (15U-shift);
3879
png_uint_16pp table = *ptable =
3880
(png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
3882
for (i = 0; i < num; i++)
3884
png_uint_16p sub_table = table[i] =
3885
(png_uint_16p)png_malloc(png_ptr, 256 * (sizeof (png_uint_16)));
3887
/* The 'threshold' test is repeated here because it can arise for one of
3888
* the 16-bit tables even if the others don't hit it.
3890
if (png_gamma_significant(gamma_val) != 0)
3892
/* The old code would overflow at the end and this would cause the
3893
* 'pow' function to return a result >1, resulting in an
3894
* arithmetic error. This code follows the spec exactly; ig is
3895
* the recovered input sample, it always has 8-16 bits.
3897
* We want input * 65535/max, rounded, the arithmetic fits in 32
3898
* bits (unsigned) so long as max <= 32767.
3901
for (j = 0; j < 256; j++)
3903
png_uint_32 ig = (j << (8-shift)) + i;
3904
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3905
/* Inline the 'max' scaling operation: */
3906
/* See png_gamma_8bit_correct for why the cast to (int) is
3909
double d = floor(65535.*pow(ig*fmax, gamma_val*.00001)+.5);
3910
sub_table[j] = (png_uint_16)d;
3913
ig = (ig * 65535U + max_by_2)/max;
3915
sub_table[j] = png_gamma_16bit_correct(ig, gamma_val);
3921
/* We must still build a table, but do it the fast way. */
3924
for (j = 0; j < 256; j++)
3926
png_uint_32 ig = (j << (8-shift)) + i;
3929
ig = (ig * 65535U + max_by_2)/max;
3931
sub_table[j] = (png_uint_16)ig;
3937
/* NOTE: this function expects the *inverse* of the overall gamma transformation
3941
png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
3942
PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
3944
PNG_CONST unsigned int num = 1U << (8U - shift);
3945
PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
3949
png_uint_16pp table = *ptable =
3950
(png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
3952
/* 'num' is the number of tables and also the number of low bits of low
3953
* bits of the input 16-bit value used to select a table. Each table is
3954
* itself indexed by the high 8 bits of the value.
3956
for (i = 0; i < num; i++)
3957
table[i] = (png_uint_16p)png_malloc(png_ptr,
3958
256 * (sizeof (png_uint_16)));
3960
/* 'gamma_val' is set to the reciprocal of the value calculated above, so
3961
* pow(out,g) is an *input* value. 'last' is the last input value set.
3963
* In the loop 'i' is used to find output values. Since the output is
3964
* 8-bit there are only 256 possible values. The tables are set up to
3965
* select the closest possible output value for each input by finding
3966
* the input value at the boundary between each pair of output values
3967
* and filling the table up to that boundary with the lower output
3970
* The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit
3971
* values the code below uses a 16-bit value in i; the values start at
3972
* 128.5 (for 0.5) and step by 257, for a total of 254 values (the last
3973
* entries are filled with 255). Start i at 128 and fill all 'last'
3974
* table entries <= 'max'
3977
for (i = 0; i < 255; ++i) /* 8-bit output value */
3979
/* Find the corresponding maximum input value */
3980
png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */
3982
/* Find the boundary value in 16 bits: */
3983
png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val);
3985
/* Adjust (round) to (16-shift) bits: */
3986
bound = (bound * max + 32768U)/65535U + 1U;
3988
while (last < bound)
3990
table[last & (0xffU >> shift)][last >> (8U - shift)] = out;
3995
/* And fill in the final entries. */
3996
while (last < (num << 8))
3998
table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U;
4004
/* Build a single 8-bit table: same as the 16-bit case but much simpler (and
4005
* typically much faster). Note that libpng currently does no sBIT processing
4006
* (apparently contrary to the spec) so a 256-entry table is always generated.
4009
png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
4010
PNG_CONST png_fixed_point gamma_val)
4013
png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
4015
if (png_gamma_significant(gamma_val) != 0)
4016
for (i=0; i<256; i++)
4017
table[i] = png_gamma_8bit_correct(i, gamma_val);
4020
for (i=0; i<256; ++i)
4021
table[i] = (png_byte)(i & 0xff);
4024
/* Used from png_read_destroy and below to release the memory used by the gamma
4028
png_destroy_gamma_table(png_structrp png_ptr)
4030
png_free(png_ptr, png_ptr->gamma_table);
4031
png_ptr->gamma_table = NULL;
4033
#ifdef PNG_16BIT_SUPPORTED
4034
if (png_ptr->gamma_16_table != NULL)
4037
int istop = (1 << (8 - png_ptr->gamma_shift));
4038
for (i = 0; i < istop; i++)
4040
png_free(png_ptr, png_ptr->gamma_16_table[i]);
4042
png_free(png_ptr, png_ptr->gamma_16_table);
4043
png_ptr->gamma_16_table = NULL;
4047
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
4048
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
4049
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
4050
png_free(png_ptr, png_ptr->gamma_from_1);
4051
png_ptr->gamma_from_1 = NULL;
4052
png_free(png_ptr, png_ptr->gamma_to_1);
4053
png_ptr->gamma_to_1 = NULL;
4055
#ifdef PNG_16BIT_SUPPORTED
4056
if (png_ptr->gamma_16_from_1 != NULL)
4059
int istop = (1 << (8 - png_ptr->gamma_shift));
4060
for (i = 0; i < istop; i++)
4062
png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
4064
png_free(png_ptr, png_ptr->gamma_16_from_1);
4065
png_ptr->gamma_16_from_1 = NULL;
4067
if (png_ptr->gamma_16_to_1 != NULL)
4070
int istop = (1 << (8 - png_ptr->gamma_shift));
4071
for (i = 0; i < istop; i++)
4073
png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
4075
png_free(png_ptr, png_ptr->gamma_16_to_1);
4076
png_ptr->gamma_16_to_1 = NULL;
4079
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
4082
/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit
4083
* tables, we don't make a full table if we are reducing to 8-bit in
4084
* the future. Note also how the gamma_16 tables are segmented so that
4085
* we don't need to allocate > 64K chunks for a full 16-bit table.
4088
png_build_gamma_table(png_structrp png_ptr, int bit_depth)
4090
png_debug(1, "in png_build_gamma_table");
4092
/* Remove any existing table; this copes with multiple calls to
4093
* png_read_update_info. The warning is because building the gamma tables
4094
* multiple times is a performance hit - it's harmless but the ability to call
4095
* png_read_update_info() multiple times is new in 1.5.6 so it seems sensible
4096
* to warn if the app introduces such a hit.
4098
if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
4100
png_warning(png_ptr, "gamma table being rebuilt");
4101
png_destroy_gamma_table(png_ptr);
4106
png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
4107
png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
4108
png_ptr->screen_gamma) : PNG_FP_1);
4110
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
4111
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
4112
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
4113
if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
4115
png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
4116
png_reciprocal(png_ptr->colorspace.gamma));
4118
png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
4119
png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
4120
png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
4122
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
4124
#ifdef PNG_16BIT_SUPPORTED
4127
png_byte shift, sig_bit;
4129
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
4131
sig_bit = png_ptr->sig_bit.red;
4133
if (png_ptr->sig_bit.green > sig_bit)
4134
sig_bit = png_ptr->sig_bit.green;
4136
if (png_ptr->sig_bit.blue > sig_bit)
4137
sig_bit = png_ptr->sig_bit.blue;
4140
sig_bit = png_ptr->sig_bit.gray;
4142
/* 16-bit gamma code uses this equation:
4144
* ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
4146
* Where 'iv' is the input color value and 'ov' is the output value -
4149
* Thus the gamma table consists of up to 256 256-entry tables. The table
4150
* is selected by the (8-gamma_shift) most significant of the low 8 bits of
4151
* the color value then indexed by the upper 8 bits:
4153
* table[low bits][high 8 bits]
4155
* So the table 'n' corresponds to all those 'iv' of:
4157
* <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
4160
if (sig_bit > 0 && sig_bit < 16U)
4161
/* shift == insignificant bits */
4162
shift = (png_byte)((16U - sig_bit) & 0xff);
4165
shift = 0; /* keep all 16 bits */
4167
if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
4169
/* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
4170
* the significant bits in the *input* when the output will
4171
* eventually be 8 bits. By default it is 11.
4173
if (shift < (16U - PNG_MAX_GAMMA_8))
4174
shift = (16U - PNG_MAX_GAMMA_8);
4178
shift = 8U; /* Guarantees at least one table! */
4180
png_ptr->gamma_shift = shift;
4182
/* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
4183
* PNG_COMPOSE). This effectively smashed the background calculation for
4184
* 16-bit output because the 8-bit table assumes the result will be reduced
4187
if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
4188
png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
4189
png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
4190
png_ptr->screen_gamma) : PNG_FP_1);
4193
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
4194
png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
4195
png_ptr->screen_gamma) : PNG_FP_1);
4197
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
4198
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
4199
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
4200
if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
4202
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
4203
png_reciprocal(png_ptr->colorspace.gamma));
4205
/* Notice that the '16 from 1' table should be full precision, however
4206
* the lookup on this table still uses gamma_shift, so it can't be.
4209
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
4210
png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
4211
png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
4213
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
4217
#endif /* READ_GAMMA */
4219
/* HARDWARE OR SOFTWARE OPTION SUPPORT */
4220
#ifdef PNG_SET_OPTION_SUPPORTED
4222
png_set_option(png_structrp png_ptr, int option, int onoff)
4224
if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
4227
int mask = 3 << option;
4228
int setting = (2 + (onoff != 0)) << option;
4229
int current = png_ptr->options;
4231
png_ptr->options = (png_byte)(((current & ~mask) | setting) & 0xff);
4233
return (current & mask) >> option;
4236
return PNG_OPTION_INVALID;
4241
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
4242
defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
4243
/* sRGB conversion tables; these are machine generated with the code in
4244
* contrib/tools/makesRGB.c. The actual sRGB transfer curve defined in the
4245
* specification (see the article at http://en.wikipedia.org/wiki/SRGB)
4246
* is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
4247
* The sRGB to linear table is exact (to the nearest 16-bit linear fraction).
4248
* The inverse (linear to sRGB) table has accuracies as follows:
4250
* For all possible (255*65535+1) input values:
4252
* error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact
4254
* For the input values corresponding to the 65536 16-bit values:
4256
* error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact
4258
* In all cases the inexact readings are only off by one.
4261
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
4262
/* The convert-to-sRGB table is only currently required for read. */
4263
const png_uint_16 png_sRGB_table[256] =
4265
0,20,40,60,80,99,119,139,
4266
159,179,199,219,241,264,288,313,
4267
340,367,396,427,458,491,526,562,
4268
599,637,677,718,761,805,851,898,
4269
947,997,1048,1101,1156,1212,1270,1330,
4270
1391,1453,1517,1583,1651,1720,1790,1863,
4271
1937,2013,2090,2170,2250,2333,2418,2504,
4272
2592,2681,2773,2866,2961,3058,3157,3258,
4273
3360,3464,3570,3678,3788,3900,4014,4129,
4274
4247,4366,4488,4611,4736,4864,4993,5124,
4275
5257,5392,5530,5669,5810,5953,6099,6246,
4276
6395,6547,6700,6856,7014,7174,7335,7500,
4277
7666,7834,8004,8177,8352,8528,8708,8889,
4278
9072,9258,9445,9635,9828,10022,10219,10417,
4279
10619,10822,11028,11235,11446,11658,11873,12090,
4280
12309,12530,12754,12980,13209,13440,13673,13909,
4281
14146,14387,14629,14874,15122,15371,15623,15878,
4282
16135,16394,16656,16920,17187,17456,17727,18001,
4283
18277,18556,18837,19121,19407,19696,19987,20281,
4284
20577,20876,21177,21481,21787,22096,22407,22721,
4285
23038,23357,23678,24002,24329,24658,24990,25325,
4286
25662,26001,26344,26688,27036,27386,27739,28094,
4287
28452,28813,29176,29542,29911,30282,30656,31033,
4288
31412,31794,32179,32567,32957,33350,33745,34143,
4289
34544,34948,35355,35764,36176,36591,37008,37429,
4290
37852,38278,38706,39138,39572,40009,40449,40891,
4291
41337,41785,42236,42690,43147,43606,44069,44534,
4292
45002,45473,45947,46423,46903,47385,47871,48359,
4293
48850,49344,49841,50341,50844,51349,51858,52369,
4294
52884,53401,53921,54445,54971,55500,56032,56567,
4295
57105,57646,58190,58737,59287,59840,60396,60955,
4296
61517,62082,62650,63221,63795,64372,64952,65535
4298
#endif /* SIMPLIFIED_READ */
4300
/* The base/delta tables are required for both read and write (but currently
4301
* only the simplified versions.)
4303
const png_uint_16 png_sRGB_base[512] =
4305
128,1782,3383,4644,5675,6564,7357,8074,
4306
8732,9346,9921,10463,10977,11466,11935,12384,
4307
12816,13233,13634,14024,14402,14769,15125,15473,
4308
15812,16142,16466,16781,17090,17393,17690,17981,
4309
18266,18546,18822,19093,19359,19621,19879,20133,
4310
20383,20630,20873,21113,21349,21583,21813,22041,
4311
22265,22487,22707,22923,23138,23350,23559,23767,
4312
23972,24175,24376,24575,24772,24967,25160,25352,
4313
25542,25730,25916,26101,26284,26465,26645,26823,
4314
27000,27176,27350,27523,27695,27865,28034,28201,
4315
28368,28533,28697,28860,29021,29182,29341,29500,
4316
29657,29813,29969,30123,30276,30429,30580,30730,
4317
30880,31028,31176,31323,31469,31614,31758,31902,
4318
32045,32186,32327,32468,32607,32746,32884,33021,
4319
33158,33294,33429,33564,33697,33831,33963,34095,
4320
34226,34357,34486,34616,34744,34873,35000,35127,
4321
35253,35379,35504,35629,35753,35876,35999,36122,
4322
36244,36365,36486,36606,36726,36845,36964,37083,
4323
37201,37318,37435,37551,37668,37783,37898,38013,
4324
38127,38241,38354,38467,38580,38692,38803,38915,
4325
39026,39136,39246,39356,39465,39574,39682,39790,
4326
39898,40005,40112,40219,40325,40431,40537,40642,
4327
40747,40851,40955,41059,41163,41266,41369,41471,
4328
41573,41675,41777,41878,41979,42079,42179,42279,
4329
42379,42478,42577,42676,42775,42873,42971,43068,
4330
43165,43262,43359,43456,43552,43648,43743,43839,
4331
43934,44028,44123,44217,44311,44405,44499,44592,
4332
44685,44778,44870,44962,45054,45146,45238,45329,
4333
45420,45511,45601,45692,45782,45872,45961,46051,
4334
46140,46229,46318,46406,46494,46583,46670,46758,
4335
46846,46933,47020,47107,47193,47280,47366,47452,
4336
47538,47623,47709,47794,47879,47964,48048,48133,
4337
48217,48301,48385,48468,48552,48635,48718,48801,
4338
48884,48966,49048,49131,49213,49294,49376,49458,
4339
49539,49620,49701,49782,49862,49943,50023,50103,
4340
50183,50263,50342,50422,50501,50580,50659,50738,
4341
50816,50895,50973,51051,51129,51207,51285,51362,
4342
51439,51517,51594,51671,51747,51824,51900,51977,
4343
52053,52129,52205,52280,52356,52432,52507,52582,
4344
52657,52732,52807,52881,52956,53030,53104,53178,
4345
53252,53326,53400,53473,53546,53620,53693,53766,
4346
53839,53911,53984,54056,54129,54201,54273,54345,
4347
54417,54489,54560,54632,54703,54774,54845,54916,
4348
54987,55058,55129,55199,55269,55340,55410,55480,
4349
55550,55620,55689,55759,55828,55898,55967,56036,
4350
56105,56174,56243,56311,56380,56448,56517,56585,
4351
56653,56721,56789,56857,56924,56992,57059,57127,
4352
57194,57261,57328,57395,57462,57529,57595,57662,
4353
57728,57795,57861,57927,57993,58059,58125,58191,
4354
58256,58322,58387,58453,58518,58583,58648,58713,
4355
58778,58843,58908,58972,59037,59101,59165,59230,
4356
59294,59358,59422,59486,59549,59613,59677,59740,
4357
59804,59867,59930,59993,60056,60119,60182,60245,
4358
60308,60370,60433,60495,60558,60620,60682,60744,
4359
60806,60868,60930,60992,61054,61115,61177,61238,
4360
61300,61361,61422,61483,61544,61605,61666,61727,
4361
61788,61848,61909,61969,62030,62090,62150,62211,
4362
62271,62331,62391,62450,62510,62570,62630,62689,
4363
62749,62808,62867,62927,62986,63045,63104,63163,
4364
63222,63281,63340,63398,63457,63515,63574,63632,
4365
63691,63749,63807,63865,63923,63981,64039,64097,
4366
64155,64212,64270,64328,64385,64443,64500,64557,
4367
64614,64672,64729,64786,64843,64900,64956,65013,
4368
65070,65126,65183,65239,65296,65352,65409,65465
4371
const png_byte png_sRGB_delta[512] =
4373
207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54,
4374
52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,
4375
35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28,
4376
28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24,
4377
23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21,
4378
21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19,
4379
19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17,
4380
17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16,
4381
16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15,
4382
15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14,
4383
14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13,
4384
13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12,
4385
12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,
4386
12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11,
4387
11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
4388
11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
4389
11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
4390
10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
4391
10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
4392
10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
4393
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
4394
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
4395
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
4396
9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
4397
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
4398
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
4399
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
4400
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
4401
8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7,
4402
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
4403
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
4404
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
4406
#endif /* SIMPLIFIED READ/WRITE sRGB support */
4408
/* SIMPLIFIED READ/WRITE SUPPORT */
4409
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
4410
defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
4412
png_image_free_function(png_voidp argument)
4414
png_imagep image = png_voidcast(png_imagep, argument);
4415
png_controlp cp = image->opaque;
4418
/* Double check that we have a png_ptr - it should be impossible to get here
4421
if (cp->png_ptr == NULL)
4424
/* First free any data held in the control structure. */
4425
# ifdef PNG_STDIO_SUPPORTED
4426
if (cp->owned_file != 0)
4428
FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr);
4431
/* Ignore errors here. */
4434
cp->png_ptr->io_ptr = NULL;
4440
/* Copy the control structure so that the original, allocated, version can be
4441
* safely freed. Notice that a png_error here stops the remainder of the
4442
* cleanup, but this is probably fine because that would indicate bad memory
4447
png_free(c.png_ptr, cp);
4449
/* Then the structures, calling the correct API. */
4450
if (c.for_write != 0)
4452
# ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
4453
png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
4455
png_error(c.png_ptr, "simplified write not supported");
4460
# ifdef PNG_SIMPLIFIED_READ_SUPPORTED
4461
png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL);
4463
png_error(c.png_ptr, "simplified read not supported");
4472
png_image_free(png_imagep image)
4474
/* Safely call the real function, but only if doing so is safe at this point
4475
* (if not inside an error handling context). Otherwise assume
4476
* png_safe_execute will call this API after the return.
4478
if (image != NULL && image->opaque != NULL &&
4479
image->opaque->error_buf == NULL)
4481
/* Ignore errors here: */
4482
(void)png_safe_execute(image, png_image_free_function, image);
4483
image->opaque = NULL;
4488
png_image_error(png_imagep image, png_const_charp error_message)
4490
/* Utility to log an error. */
4491
png_safecat(image->message, (sizeof image->message), 0, error_message);
4492
image->warning_or_error |= PNG_IMAGE_ERROR;
4493
png_image_free(image);
4497
#endif /* SIMPLIFIED READ/WRITE */
4498
#endif /* READ || WRITE */