2
/* png.c - location for general purpose libpng functions
4
* Copyright (c) 2018-2024 Cosmin Truta
5
* Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
6
* Copyright (c) 1996-1997 Andreas Dilger
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* 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
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* and license in png.h
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/* 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_43 Your_png_h_is_not_version_1_6_43;
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/* 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
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* 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)
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unsigned int nb = (unsigned int)num_bytes;
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png_debug(1, "in png_set_sig_bytes");
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png_error(png_ptr, "Too many bytes for PNG signature");
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png_ptr->sig_bytes = (png_byte)nb;
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/* Checks whether the supplied bytes match the PNG signature. We allow
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* checking less than the full 8-byte signature so that those apps that
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* already read the first few bytes of a file to determine the file type
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* can simply check the remaining bytes for extra assurance. Returns
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* an integer less than, equal to, or greater than zero if sig is found,
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* respectively, to be less than, to match, or be greater than the correct
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* PNG signature (this is the same behavior as strcmp, memcmp, etc).
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png_sig_cmp(png_const_bytep sig, size_t start, size_t num_to_check)
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static const png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};61
else if (num_to_check < 1)
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if (start + num_to_check > 8)
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num_to_check = 8 - start;
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return memcmp(&sig[start], &png_signature[start], num_to_check);
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#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
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/* Function to allocate memory for zlib */
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PNG_FUNCTION(voidpf /* PRIVATE */,
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png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED)
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png_alloc_size_t num_bytes = size;
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if (items >= (~(png_alloc_size_t)0)/size)
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png_warning (png_voidcast(png_structrp, png_ptr),
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"Potential overflow in png_zalloc()");
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return png_malloc_warn(png_voidcast(png_structrp, png_ptr), num_bytes);
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/* Function to free memory for zlib */
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png_zfree(voidpf png_ptr, voidpf ptr)
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png_free(png_voidcast(png_const_structrp,png_ptr), ptr);
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/* Reset the CRC variable to 32 bits of 1's. Care must be taken
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* in case CRC is > 32 bits to leave the top bits 0.
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png_reset_crc(png_structrp png_ptr)
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/* The cast is safe because the crc is a 32-bit value. */
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png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0);
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/* Calculate the CRC over a section of data. We can only pass as
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* much data to this routine as the largest single buffer size. We
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* also check that this data will actually be used before going to the
116
* trouble of calculating it.
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png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, 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) ==
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(PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
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if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
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/* 'uLong' is defined in zlib.h as unsigned long; this means that on some
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* systems it is a 64-bit value. crc32, however, returns 32 bits so the
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* following cast is safe. 'uInt' may be no more than 16 bits, so it is
139
* necessary to perform a loop here.
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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 */
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crc = crc32(crc, ptr, safe_length);
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/* The following should never issue compiler warnings; if they do the
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* target system has characteristics that will probably violate other
157
* assumptions within the libpng code.
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length -= safe_length;
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/* And the following is always safe because the crc is only 32 bits. */
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png_ptr->crc = (png_uint_32)crc;
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/* Check a user supplied version number, called from both read and write
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* functions that create a png_struct.
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png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver)
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/* Libpng versions 1.0.0 and later are binary compatible if the version
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* string matches through the second '.'; we must recompile any
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* 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;
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if (user_png_ver[i] == '.')
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} while (found_dots < 2 && user_png_ver[i] != 0 &&
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PNG_LIBPNG_VER_STRING[i] != 0);
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png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
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if ((png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) != 0)
201
#ifdef PNG_WARNINGS_SUPPORTED
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pos = png_safecat(m, (sizeof m), pos,
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"Application built with libpng-");
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pos = png_safecat(m, (sizeof m), pos, user_png_ver);
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pos = png_safecat(m, (sizeof m), pos, " but running with ");
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pos = png_safecat(m, (sizeof m), pos, PNG_LIBPNG_VER_STRING);
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png_warning(png_ptr, m);
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#ifdef PNG_ERROR_NUMBERS_SUPPORTED
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/* Success return. */
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/* Generic function to create a png_struct for either read or write - this
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* contains the common initialization.
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PNG_FUNCTION(png_structp /* PRIVATE */,
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png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
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png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
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png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
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png_struct create_struct;
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# ifdef PNG_SETJMP_SUPPORTED
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jmp_buf create_jmp_buf;
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/* This temporary stack-allocated structure is used to provide a place to
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* build enough context to allow the user provided memory allocator (if any)
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memset(&create_struct, 0, (sizeof create_struct));
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/* Added at libpng-1.2.6 */
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# ifdef PNG_USER_LIMITS_SUPPORTED
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create_struct.user_width_max = PNG_USER_WIDTH_MAX;
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create_struct.user_height_max = PNG_USER_HEIGHT_MAX;
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# ifdef PNG_USER_CHUNK_CACHE_MAX
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/* Added at libpng-1.2.43 and 1.4.0 */
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create_struct.user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
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# ifdef PNG_USER_CHUNK_MALLOC_MAX
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/* Added at libpng-1.2.43 and 1.4.1, required only for read but exists
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* in png_struct regardless.
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create_struct.user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
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/* The following two API calls simply set fields in png_struct, so it is safe
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* to do them now even though error handling is not yet set up.
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# ifdef PNG_USER_MEM_SUPPORTED
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png_set_mem_fn(&create_struct, mem_ptr, malloc_fn, free_fn);
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PNG_UNUSED(malloc_fn)
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/* (*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);
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# ifdef PNG_SETJMP_SUPPORTED
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if (!setjmp(create_jmp_buf))
285
# ifdef PNG_SETJMP_SUPPORTED
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/* Temporarily fake out the longjmp information until we have
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* 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;
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create_struct.jmp_buf_size = 0; /*stack allocation*/
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create_struct.longjmp_fn = longjmp;
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/* Call the general version checker (shared with read and write code):
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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)));
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/* 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, 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));
431
png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr,
432
int freer, png_uint_32 mask)
434
png_debug(1, "in png_data_freer");
436
if (png_ptr == NULL || info_ptr == NULL)
439
if (freer == PNG_DESTROY_WILL_FREE_DATA)
440
info_ptr->free_me |= mask;
442
else if (freer == PNG_USER_WILL_FREE_DATA)
443
info_ptr->free_me &= ~mask;
446
png_error(png_ptr, "Unknown freer parameter in png_data_freer");
450
png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
453
png_debug(1, "in png_free_data");
455
if (png_ptr == NULL || info_ptr == NULL)
458
#ifdef PNG_TEXT_SUPPORTED
459
/* Free text item num or (if num == -1) all text items */
460
if (info_ptr->text != NULL &&
461
((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0)
465
png_free(png_ptr, info_ptr->text[num].key);
466
info_ptr->text[num].key = NULL;
473
for (i = 0; i < info_ptr->num_text; i++)
474
png_free(png_ptr, info_ptr->text[i].key);
476
png_free(png_ptr, info_ptr->text);
477
info_ptr->text = NULL;
478
info_ptr->num_text = 0;
479
info_ptr->max_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 != NULL &&
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 != NULL &&
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_eXIf_SUPPORTED
598
/* Free any eXIf entry */
599
if (((mask & PNG_FREE_EXIF) & info_ptr->free_me) != 0)
601
# ifdef PNG_READ_eXIf_SUPPORTED
602
if (info_ptr->eXIf_buf)
604
png_free(png_ptr, info_ptr->eXIf_buf);
605
info_ptr->eXIf_buf = NULL;
610
png_free(png_ptr, info_ptr->exif);
611
info_ptr->exif = NULL;
613
info_ptr->valid &= ~PNG_INFO_eXIf;
617
#ifdef PNG_hIST_SUPPORTED
618
/* Free any hIST entry */
619
if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0)
621
png_free(png_ptr, info_ptr->hist);
622
info_ptr->hist = NULL;
623
info_ptr->valid &= ~PNG_INFO_hIST;
627
/* Free any PLTE entry that was internally allocated */
628
if (((mask & PNG_FREE_PLTE) & info_ptr->free_me) != 0)
630
png_free(png_ptr, info_ptr->palette);
631
info_ptr->palette = NULL;
632
info_ptr->valid &= ~PNG_INFO_PLTE;
633
info_ptr->num_palette = 0;
636
#ifdef PNG_INFO_IMAGE_SUPPORTED
637
/* Free any image bits attached to the info structure */
638
if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
640
if (info_ptr->row_pointers != NULL)
643
for (row = 0; row < info_ptr->height; row++)
644
png_free(png_ptr, info_ptr->row_pointers[row]);
646
png_free(png_ptr, info_ptr->row_pointers);
647
info_ptr->row_pointers = NULL;
649
info_ptr->valid &= ~PNG_INFO_IDAT;
654
mask &= ~PNG_FREE_MUL;
656
info_ptr->free_me &= ~mask;
658
#endif /* READ || WRITE */
660
/* This function returns a pointer to the io_ptr associated with the user
661
* functions. The application should free any memory associated with this
662
* pointer before png_write_destroy() or png_read_destroy() are called.
665
png_get_io_ptr(png_const_structrp png_ptr)
670
return png_ptr->io_ptr;
673
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
674
# ifdef PNG_STDIO_SUPPORTED
675
/* Initialize the default input/output functions for the PNG file. If you
676
* use your own read or write routines, you can call either png_set_read_fn()
677
* or png_set_write_fn() instead of png_init_io(). If you have defined
678
* PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a
679
* function of your own because "FILE *" isn't necessarily available.
682
png_init_io(png_structrp png_ptr, png_FILE_p fp)
684
png_debug(1, "in png_init_io");
689
png_ptr->io_ptr = (png_voidp)fp;
693
# ifdef PNG_SAVE_INT_32_SUPPORTED
694
/* PNG signed integers are saved in 32-bit 2's complement format. ANSI C-90
695
* defines a cast of a signed integer to an unsigned integer either to preserve
696
* the value, if it is positive, or to calculate:
698
* (UNSIGNED_MAX+1) + integer
700
* Where UNSIGNED_MAX is the appropriate maximum unsigned value, so when the
701
* negative integral value is added the result will be an unsigned value
702
* corresponding to the 2's complement representation.
705
png_save_int_32(png_bytep buf, png_int_32 i)
707
png_save_uint_32(buf, (png_uint_32)i);
711
# ifdef PNG_TIME_RFC1123_SUPPORTED
712
/* Convert the supplied time into an RFC 1123 string suitable for use in
713
* a "Creation Time" or other text-based time string.
716
png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime)
718
static const char short_months[12][4] =
719
{"Jan", "Feb", "Mar", "Apr", "May", "Jun",720
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
725
if (ptime->year > 9999 /* RFC1123 limitation */ ||
726
ptime->month == 0 || ptime->month > 12 ||
727
ptime->day == 0 || ptime->day > 31 ||
728
ptime->hour > 23 || ptime->minute > 59 ||
734
char number_buf[5] = {0, 0, 0, 0, 0}; /* enough for a four-digit year */736
# define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string))
737
# define APPEND_NUMBER(format, value)\
738
APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
739
# define APPEND(ch) if (pos < 28) out[pos++] = (ch)
741
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day);
743
APPEND_STRING(short_months[(ptime->month - 1)]);
745
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year);
747
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour);
749
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute);
751
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second);
752
APPEND_STRING(" +0000"); /* This reliably terminates the buffer */763
# if PNG_LIBPNG_VER < 10700
764
/* To do: remove the following from libpng-1.7 */
765
/* Original API that uses a private buffer in png_struct.
766
* Deprecated because it causes png_struct to carry a spurious temporary
767
* buffer (png_struct::time_buffer), better to have the caller pass this in.
769
png_const_charp PNGAPI
770
png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime)
774
/* The only failure above if png_ptr != NULL is from an invalid ptime */
775
if (png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime) == 0)
776
png_warning(png_ptr, "Ignoring invalid time value");
779
return png_ptr->time_buffer;
784
# endif /* LIBPNG_VER < 10700 */
785
# endif /* TIME_RFC1123 */
787
#endif /* READ || WRITE */
789
png_const_charp PNGAPI
790
png_get_copyright(png_const_structrp png_ptr)
792
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
793
#ifdef PNG_STRING_COPYRIGHT
794
return PNG_STRING_COPYRIGHT
796
return PNG_STRING_NEWLINE \
797
"libpng version 1.6.43" PNG_STRING_NEWLINE \
798
"Copyright (c) 2018-2024 Cosmin Truta" PNG_STRING_NEWLINE \
799
"Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson" \
801
"Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
802
"Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
807
/* The following return the library version as a short string in the
808
* format 1.0.0 through 99.99.99zz. To get the version of *.h files
809
* used with your application, print out PNG_LIBPNG_VER_STRING, which
810
* is defined in png.h.
811
* Note: now there is no difference between png_get_libpng_ver() and
812
* png_get_header_ver(). Due to the version_nn_nn_nn typedef guard,
813
* it is guaranteed that png.c uses the correct version of png.h.
815
png_const_charp PNGAPI
816
png_get_libpng_ver(png_const_structrp png_ptr)
818
/* Version of *.c files used when building libpng */
819
return png_get_header_ver(png_ptr);
822
png_const_charp PNGAPI
823
png_get_header_ver(png_const_structrp png_ptr)
825
/* Version of *.h files used when building libpng */
826
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
827
return PNG_LIBPNG_VER_STRING;
830
png_const_charp PNGAPI
831
png_get_header_version(png_const_structrp png_ptr)
833
/* Returns longer string containing both version and date */
834
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
836
return PNG_HEADER_VERSION_STRING
837
# ifndef PNG_READ_SUPPORTED
842
return PNG_HEADER_VERSION_STRING;
846
#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
847
/* NOTE: this routine is not used internally! */
848
/* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
849
* large of png_color. This lets grayscale images be treated as
850
* paletted. Most useful for gamma correction and simplification
851
* of code. This API is not used internally.
854
png_build_grayscale_palette(int bit_depth, png_colorp palette)
861
png_debug(1, "in png_do_build_grayscale_palette");
894
for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
896
palette[i].red = (png_byte)(v & 0xff);
897
palette[i].green = (png_byte)(v & 0xff);
898
palette[i].blue = (png_byte)(v & 0xff);
903
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
905
png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name)
907
/* Check chunk_name and return "keep" value if it's on the list, else 0 */
908
png_const_bytep p, p_end;
910
if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list == 0)
911
return PNG_HANDLE_CHUNK_AS_DEFAULT;
913
p_end = png_ptr->chunk_list;
914
p = p_end + png_ptr->num_chunk_list*5; /* beyond end */
916
/* The code is the fifth byte after each four byte string. Historically this
917
* code was always searched from the end of the list, this is no longer
918
* necessary because the 'set' routine handles duplicate entries correctly.
920
do /* num_chunk_list > 0, so at least one */
924
if (memcmp(chunk_name, p, 4) == 0)
929
/* This means that known chunks should be processed and unknown chunks should
930
* be handled according to the value of png_ptr->unknown_default; this can be
931
* confusing because, as a result, there are two levels of defaulting for
934
return PNG_HANDLE_CHUNK_AS_DEFAULT;
937
#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
938
defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
940
png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name)
942
png_byte chunk_string[5];
944
PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
945
return png_handle_as_unknown(png_ptr, chunk_string);
947
#endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */
948
#endif /* SET_UNKNOWN_CHUNKS */
950
#ifdef PNG_READ_SUPPORTED
951
/* This function, added to libpng-1.0.6g, is untested. */
953
png_reset_zstream(png_structrp png_ptr)
956
return Z_STREAM_ERROR;
958
/* WARNING: this resets the window bits to the maximum! */
959
return inflateReset(&png_ptr->zstream);
963
/* This function was added to libpng-1.0.7 */
965
png_access_version_number(void)
967
/* Version of *.c files used when building libpng */
968
return (png_uint_32)PNG_LIBPNG_VER;
971
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
972
/* Ensure that png_ptr->zstream.msg holds some appropriate error message string.
973
* If it doesn't 'ret' is used to set it to something appropriate, even in cases
974
* like Z_OK or Z_STREAM_END where the error code is apparently a success code.
977
png_zstream_error(png_structrp png_ptr, int ret)
979
/* Translate 'ret' into an appropriate error string, priority is given to the
980
* one in zstream if set. This always returns a string, even in cases like
981
* Z_OK or Z_STREAM_END where the error code is a success code.
983
if (png_ptr->zstream.msg == NULL) switch (ret)
987
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return code");992
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected end of LZ stream");996
/* This means the deflate stream did not have a dictionary; this
997
* indicates a bogus PNG.
999
png_ptr->zstream.msg = PNGZ_MSG_CAST("missing LZ dictionary");1003
/* gz APIs only: should not happen */
1004
png_ptr->zstream.msg = PNGZ_MSG_CAST("zlib IO error");1007
case Z_STREAM_ERROR:
1008
/* internal libpng error */
1009
png_ptr->zstream.msg = PNGZ_MSG_CAST("bad parameters to zlib");1013
png_ptr->zstream.msg = PNGZ_MSG_CAST("damaged LZ stream");1017
png_ptr->zstream.msg = PNGZ_MSG_CAST("insufficient memory");1021
/* End of input or output; not a problem if the caller is doing
1022
* incremental read or write.
1024
png_ptr->zstream.msg = PNGZ_MSG_CAST("truncated");1027
case Z_VERSION_ERROR:
1028
png_ptr->zstream.msg = PNGZ_MSG_CAST("unsupported zlib version");1031
case PNG_UNEXPECTED_ZLIB_RETURN:
1032
/* Compile errors here mean that zlib now uses the value co-opted in
1033
* pngpriv.h for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above
1034
* and change pngpriv.h. Note that this message is "... return",
1035
* whereas the default/Z_OK one is "... return code".
1037
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return");1042
/* png_convert_size: a PNGAPI but no longer in png.h, so deleted
1046
/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
1047
#ifdef PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */
1049
png_colorspace_check_gamma(png_const_structrp png_ptr,
1050
png_colorspacerp colorspace, png_fixed_point gAMA, int from)
1051
/* This is called to check a new gamma value against an existing one. The
1052
* routine returns false if the new gamma value should not be written.
1054
* 'from' says where the new gamma value comes from:
1056
* 0: the new gamma value is the libpng estimate for an ICC profile
1057
* 1: the new gamma value comes from a gAMA chunk
1058
* 2: the new gamma value comes from an sRGB chunk
1061
png_fixed_point gtest;
1063
if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
1064
(png_muldiv(>est, colorspace->gamma, PNG_FP_1, gAMA) == 0 ||
1065
png_gamma_significant(gtest) != 0))
1067
/* Either this is an sRGB image, in which case the calculated gamma
1068
* approximation should match, or this is an image with a profile and the
1069
* value libpng calculates for the gamma of the profile does not match the
1070
* value recorded in the file. The former, sRGB, case is an error, the
1071
* latter is just a warning.
1073
if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2)
1075
png_chunk_report(png_ptr, "gamma value does not match sRGB",
1077
/* Do not overwrite an sRGB value */
1081
else /* sRGB tag not involved */
1083
png_chunk_report(png_ptr, "gamma value does not match libpng estimate",
1093
png_colorspace_set_gamma(png_const_structrp png_ptr,
1094
png_colorspacerp colorspace, png_fixed_point gAMA)
1096
/* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
1097
* occur. Since the fixed point representation is asymmetrical it is
1098
* possible for 1/gamma to overflow the limit of 21474 and this means the
1099
* gamma value must be at least 5/100000 and hence at most 20000.0. For
1100
* safety the limits here are a little narrower. The values are 0.00016 to
1101
* 6250.0, which are truly ridiculous gamma values (and will produce
1102
* displays that are all black or all white.)
1104
* In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk
1105
* handling code, which only required the value to be >0.
1107
png_const_charp errmsg;
1109
if (gAMA < 16 || gAMA > 625000000)
1110
errmsg = "gamma value out of range";
1112
# ifdef PNG_READ_gAMA_SUPPORTED
1113
/* Allow the application to set the gamma value more than once */
1114
else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
1115
(colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0)
1116
errmsg = "duplicate";
1119
/* Do nothing if the colorspace is already invalid */
1120
else if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
1125
if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA,
1126
1/*from gAMA*/) != 0)
1128
/* Store this gamma value. */
1129
colorspace->gamma = gAMA;
1130
colorspace->flags |=
1131
(PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA);
1134
/* At present if the check_gamma test fails the gamma of the colorspace is
1135
* not updated however the colorspace is not invalidated. This
1136
* corresponds to the case where the existing gamma comes from an sRGB
1137
* chunk or profile. An error message has already been output.
1142
/* Error exit - errmsg has been set. */
1143
colorspace->flags |= PNG_COLORSPACE_INVALID;
1144
png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR);
1148
png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr)
1150
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1152
/* Everything is invalid */
1153
info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB|
1156
# ifdef PNG_COLORSPACE_SUPPORTED
1157
/* Clean up the iCCP profile now if it won't be used. */
1158
png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, -1/*not used*/);
1166
# ifdef PNG_COLORSPACE_SUPPORTED
1167
/* Leave the INFO_iCCP flag set if the pngset.c code has already set
1168
* it; this allows a PNG to contain a profile which matches sRGB and
1169
* yet still have that profile retrievable by the application.
1171
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB) != 0)
1172
info_ptr->valid |= PNG_INFO_sRGB;
1175
info_ptr->valid &= ~PNG_INFO_sRGB;
1177
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
1178
info_ptr->valid |= PNG_INFO_cHRM;
1181
info_ptr->valid &= ~PNG_INFO_cHRM;
1184
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0)
1185
info_ptr->valid |= PNG_INFO_gAMA;
1188
info_ptr->valid &= ~PNG_INFO_gAMA;
1192
#ifdef PNG_READ_SUPPORTED
1194
png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr)
1196
if (info_ptr == NULL) /* reduce code size; check here not in the caller */
1199
info_ptr->colorspace = png_ptr->colorspace;
1200
png_colorspace_sync_info(png_ptr, info_ptr);
1205
#ifdef PNG_COLORSPACE_SUPPORTED
1206
/* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
1207
* cHRM, as opposed to using chromaticities. These internal APIs return
1208
* non-zero on a parameter error. The X, Y and Z values are required to be
1209
* positive and less than 1.0.
1212
png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
1214
png_int_32 d, dwhite, whiteX, whiteY;
1216
d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
1217
if (png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d) == 0)
1219
if (png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d) == 0)
1222
whiteX = XYZ->red_X;
1223
whiteY = XYZ->red_Y;
1225
d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
1226
if (png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d) == 0)
1228
if (png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d) == 0)
1231
whiteX += XYZ->green_X;
1232
whiteY += XYZ->green_Y;
1234
d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
1235
if (png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d) == 0)
1237
if (png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d) == 0)
1240
whiteX += XYZ->blue_X;
1241
whiteY += XYZ->blue_Y;
1243
/* The reference white is simply the sum of the end-point (X,Y,Z) vectors,
1246
if (png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite) == 0)
1248
if (png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite) == 0)
1255
png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
1257
png_fixed_point red_inverse, green_inverse, blue_scale;
1258
png_fixed_point left, right, denominator;
1260
/* Check xy and, implicitly, z. Note that wide gamut color spaces typically
1261
* have end points with 0 tristimulus values (these are impossible end
1262
* points, but they are used to cover the possible colors). We check
1263
* xy->whitey against 5, not 0, to avoid a possible integer overflow.
1265
if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1;
1266
if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1;
1267
if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1;
1268
if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1;
1269
if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1;
1270
if (xy->bluey < 0 || xy->bluey > PNG_FP_1-xy->bluex) return 1;
1271
if (xy->whitex < 0 || xy->whitex > PNG_FP_1) return 1;
1272
if (xy->whitey < 5 || xy->whitey > PNG_FP_1-xy->whitex) return 1;
1274
/* The reverse calculation is more difficult because the original tristimulus
1275
* value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8
1276
* derived values were recorded in the cHRM chunk;
1277
* (red,green,blue,white)x(x,y). This loses one degree of freedom and
1278
* therefore an arbitrary ninth value has to be introduced to undo the
1279
* original transformations.
1281
* Think of the original end-points as points in (X,Y,Z) space. The
1282
* chromaticity values (c) have the property:
1288
* For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the
1289
* three chromaticity values (x,y,z) for each end-point obey the
1294
* This describes the plane in (X,Y,Z) space that intersects each axis at the
1295
* value 1.0; call this the chromaticity plane. Thus the chromaticity
1296
* calculation has scaled each end-point so that it is on the x+y+z=1 plane
1297
* and chromaticity is the intersection of the vector from the origin to the
1298
* (X,Y,Z) value with the chromaticity plane.
1300
* To fully invert the chromaticity calculation we would need the three
1301
* end-point scale factors, (red-scale, green-scale, blue-scale), but these
1302
* were not recorded. Instead we calculated the reference white (X,Y,Z) and
1303
* recorded the chromaticity of this. The reference white (X,Y,Z) would have
1304
* given all three of the scale factors since:
1306
* color-C = color-c * color-scale
1307
* white-C = red-C + green-C + blue-C
1308
* = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
1310
* But cHRM records only white-x and white-y, so we have lost the white scale
1313
* white-C = white-c*white-scale
1315
* To handle this the inverse transformation makes an arbitrary assumption
1316
* about white-scale:
1318
* Assume: white-Y = 1.0
1319
* Hence: white-scale = 1/white-y
1320
* Or: red-Y + green-Y + blue-Y = 1.0
1322
* Notice the last statement of the assumption gives an equation in three of
1323
* the nine values we want to calculate. 8 more equations come from the
1324
* above routine as summarised at the top above (the chromaticity
1327
* Given: color-x = color-X / (color-X + color-Y + color-Z)
1328
* Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0
1330
* This is 9 simultaneous equations in the 9 variables "color-C" and can be
1331
* solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix
1332
* determinants, however this is not as bad as it seems because only 28 of
1333
* the total of 90 terms in the various matrices are non-zero. Nevertheless
1334
* Cramer's rule is notoriously numerically unstable because the determinant
1335
* calculation involves the difference of large, but similar, numbers. It is
1336
* difficult to be sure that the calculation is stable for real world values
1337
* and it is certain that it becomes unstable where the end points are close
1340
* So this code uses the perhaps slightly less optimal but more
1341
* understandable and totally obvious approach of calculating color-scale.
1343
* This algorithm depends on the precision in white-scale and that is
1344
* (1/white-y), so we can immediately see that as white-y approaches 0 the
1345
* accuracy inherent in the cHRM chunk drops off substantially.
1347
* libpng arithmetic: a simple inversion of the above equations
1348
* ------------------------------------------------------------
1350
* white_scale = 1/white-y
1351
* white-X = white-x * white-scale
1353
* white-Z = (1 - white-x - white-y) * white_scale
1355
* white-C = red-C + green-C + blue-C
1356
* = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
1358
* This gives us three equations in (red-scale,green-scale,blue-scale) where
1359
* all the coefficients are now known:
1361
* red-x*red-scale + green-x*green-scale + blue-x*blue-scale
1363
* red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1
1364
* red-z*red-scale + green-z*green-scale + blue-z*blue-scale
1365
* = (1 - white-x - white-y)/white-y
1367
* In the last equation color-z is (1 - color-x - color-y) so we can add all
1368
* three equations together to get an alternative third:
1370
* red-scale + green-scale + blue-scale = 1/white-y = white-scale
1372
* So now we have a Cramer's rule solution where the determinants are just
1373
* 3x3 - far more tractible. Unfortunately 3x3 determinants still involve
1374
* multiplication of three coefficients so we can't guarantee to avoid
1375
* overflow in the libpng fixed point representation. Using Cramer's rule in
1376
* floating point is probably a good choice here, but it's not an option for
1377
* fixed point. Instead proceed to simplify the first two equations by
1378
* eliminating what is likely to be the largest value, blue-scale:
1380
* blue-scale = white-scale - red-scale - green-scale
1384
* (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale =
1385
* (white-x - blue-x)*white-scale
1387
* (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale =
1388
* 1 - blue-y*white-scale
1390
* And now we can trivially solve for (red-scale,green-scale):
1393
* (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale
1394
* -----------------------------------------------------------
1398
* 1 - blue-y*white-scale - (green-y - blue-y) * green-scale
1399
* ---------------------------------------------------------
1405
* ( (green-x - blue-x) * (white-y - blue-y) -
1406
* (green-y - blue-y) * (white-x - blue-x) ) / white-y
1407
* -------------------------------------------------------------------------
1408
* (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
1411
* ( (red-y - blue-y) * (white-x - blue-x) -
1412
* (red-x - blue-x) * (white-y - blue-y) ) / white-y
1413
* -------------------------------------------------------------------------
1414
* (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
1417
* The input values have 5 decimal digits of accuracy. The values are all in
1418
* the range 0 < value < 1, so simple products are in the same range but may
1419
* need up to 10 decimal digits to preserve the original precision and avoid
1420
* underflow. Because we are using a 32-bit signed representation we cannot
1421
* match this; the best is a little over 9 decimal digits, less than 10.
1423
* The approach used here is to preserve the maximum precision within the
1424
* signed representation. Because the red-scale calculation above uses the
1425
* difference between two products of values that must be in the range -1..+1
1426
* it is sufficient to divide the product by 7; ceil(100,000/32767*2). The
1427
* factor is irrelevant in the calculation because it is applied to both
1428
* numerator and denominator.
1430
* Note that the values of the differences of the products of the
1431
* chromaticities in the above equations tend to be small, for example for
1432
* the sRGB chromaticities they are:
1434
* red numerator: -0.04751
1435
* green numerator: -0.08788
1436
* denominator: -0.2241 (without white-y multiplication)
1438
* The resultant Y coefficients from the chromaticities of some widely used
1439
* color space definitions are (to 15 decimal places):
1442
* 0.212639005871510 0.715168678767756 0.072192315360734
1444
* 0.288071128229293 0.711843217810102 0.000085653960605
1446
* 0.297344975250536 0.627363566255466 0.075291458493998
1447
* Adobe Wide Gamut RGB
1448
* 0.258728243040113 0.724682314948566 0.016589442011321
1450
/* By the argument, above overflow should be impossible here. The return
1451
* value of 2 indicates an internal error to the caller.
1453
if (png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7) == 0)
1455
if (png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7) == 0)
1457
denominator = left - right;
1459
/* Now find the red numerator. */
1460
if (png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
1462
if (png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
1465
/* Overflow is possible here and it indicates an extreme set of PNG cHRM
1466
* chunk values. This calculation actually returns the reciprocal of the
1467
* scale value because this allows us to delay the multiplication of white-y
1468
* into the denominator, which tends to produce a small number.
1470
if (png_muldiv(&red_inverse, xy->whitey, denominator, left-right) == 0 ||
1471
red_inverse <= xy->whitey /* r+g+b scales = white scale */)
1474
/* Similarly for green_inverse: */
1475
if (png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
1477
if (png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
1479
if (png_muldiv(&green_inverse, xy->whitey, denominator, left-right) == 0 ||
1480
green_inverse <= xy->whitey)
1483
/* And the blue scale, the checks above guarantee this can't overflow but it
1484
* can still produce 0 for extreme cHRM values.
1486
blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) -
1487
png_reciprocal(green_inverse);
1488
if (blue_scale <= 0)
1492
/* And fill in the png_XYZ: */
1493
if (png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse) == 0)
1495
if (png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse) == 0)
1497
if (png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
1501
if (png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse) == 0)
1503
if (png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse) == 0)
1505
if (png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
1506
green_inverse) == 0)
1509
if (png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1) == 0)
1511
if (png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1) == 0)
1513
if (png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
1517
return 0; /*success*/
1521
png_XYZ_normalize(png_XYZ *XYZ)
1525
if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 ||
1526
XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 ||
1527
XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0)
1530
/* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1.
1531
* IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore
1532
* relying on addition of two positive values producing a negative one is not
1536
if (0x7fffffff - Y < XYZ->green_X)
1539
if (0x7fffffff - Y < XYZ->blue_X)
1545
if (png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y) == 0)
1547
if (png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y) == 0)
1549
if (png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y) == 0)
1552
if (png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y) == 0)
1554
if (png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y) == 0)
1556
if (png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y) == 0)
1559
if (png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y) == 0)
1561
if (png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y) == 0)
1563
if (png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y) == 0)
1571
png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta)
1573
/* Allow an error of +/-0.01 (absolute value) on each chromaticity */
1574
if (PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
1575
PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
1576
PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) ||
1577
PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) ||
1578
PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
1579
PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
1580
PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) ||
1581
PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta))
1586
/* Added in libpng-1.6.0, a different check for the validity of a set of cHRM
1587
* chunk chromaticities. Earlier checks used to simply look for the overflow
1588
* condition (where the determinant of the matrix to solve for XYZ ends up zero
1589
* because the chromaticity values are not all distinct.) Despite this it is
1590
* theoretically possible to produce chromaticities that are apparently valid
1591
* but that rapidly degrade to invalid, potentially crashing, sets because of
1592
* arithmetic inaccuracies when calculations are performed on them. The new
1593
* check is to round-trip xy -> XYZ -> xy and then check that the result is
1594
* within a small percentage of the original.
1597
png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy)
1602
/* As a side-effect this routine also returns the XYZ endpoints. */
1603
result = png_XYZ_from_xy(XYZ, xy);
1607
result = png_xy_from_XYZ(&xy_test, XYZ);
1611
if (png_colorspace_endpoints_match(xy, &xy_test,
1612
5/*actually, the math is pretty accurate*/) != 0)
1619
/* This is the check going the other way. The XYZ is modified to normalize it
1620
* (another side-effect) and the xy chromaticities are returned.
1623
png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ)
1628
result = png_XYZ_normalize(XYZ);
1632
result = png_xy_from_XYZ(xy, XYZ);
1637
return png_colorspace_check_xy(&XYZtemp, xy);
1640
/* Used to check for an endpoint match against sRGB */
1641
static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */
1644
/* red */ 64000, 33000,
1645
/* green */ 30000, 60000,
1646
/* blue */ 15000, 6000,
1647
/* white */ 31270, 32900
1651
png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
1652
png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
1655
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
1658
/* The consistency check is performed on the chromaticities; this factors out
1659
* variations because of the normalization (or not) of the end point Y
1662
if (preferred < 2 &&
1663
(colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
1665
/* The end points must be reasonably close to any we already have. The
1666
* following allows an error of up to +/-.001
1668
if (png_colorspace_endpoints_match(xy, &colorspace->end_points_xy,
1671
colorspace->flags |= PNG_COLORSPACE_INVALID;
1672
png_benign_error(png_ptr, "inconsistent chromaticities");
1673
return 0; /* failed */
1676
/* Only overwrite with preferred values */
1678
return 1; /* ok, but no change */
1681
colorspace->end_points_xy = *xy;
1682
colorspace->end_points_XYZ = *XYZ;
1683
colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS;
1685
/* The end points are normally quoted to two decimal digits, so allow +/-0.01
1688
if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000) != 0)
1689
colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;
1692
colorspace->flags &= PNG_COLORSPACE_CANCEL(
1693
PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
1695
return 2; /* ok and changed */
1699
png_colorspace_set_chromaticities(png_const_structrp png_ptr,
1700
png_colorspacerp colorspace, const png_xy *xy, int preferred)
1702
/* We must check the end points to ensure they are reasonable - in the past
1703
* color management systems have crashed as a result of getting bogus
1704
* colorant values, while this isn't the fault of libpng it is the
1705
* responsibility of libpng because PNG carries the bomb and libpng is in a
1706
* position to protect against it.
1710
switch (png_colorspace_check_xy(&XYZ, xy))
1712
case 0: /* success */
1713
return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
1717
/* We can't invert the chromaticities so we can't produce value XYZ
1718
* values. Likely as not a color management system will fail too.
1720
colorspace->flags |= PNG_COLORSPACE_INVALID;
1721
png_benign_error(png_ptr, "invalid chromaticities");
1725
/* libpng is broken; this should be a warning but if it happens we
1726
* want error reports so for the moment it is an error.
1728
colorspace->flags |= PNG_COLORSPACE_INVALID;
1729
png_error(png_ptr, "internal error checking chromaticities");
1732
return 0; /* failed */
1736
png_colorspace_set_endpoints(png_const_structrp png_ptr,
1737
png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
1739
png_XYZ XYZ = *XYZ_in;
1742
switch (png_colorspace_check_XYZ(&xy, &XYZ))
1745
return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
1749
/* End points are invalid. */
1750
colorspace->flags |= PNG_COLORSPACE_INVALID;
1751
png_benign_error(png_ptr, "invalid end points");
1755
colorspace->flags |= PNG_COLORSPACE_INVALID;
1756
png_error(png_ptr, "internal error checking chromaticities");
1759
return 0; /* failed */
1762
#if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED)
1763
/* Error message generation */
1765
png_icc_tag_char(png_uint_32 byte)
1768
if (byte >= 32 && byte <= 126)
1775
png_icc_tag_name(char *name, png_uint_32 tag)
1778
name[1] = png_icc_tag_char(tag >> 24);
1779
name[2] = png_icc_tag_char(tag >> 16);
1780
name[3] = png_icc_tag_char(tag >> 8);
1781
name[4] = png_icc_tag_char(tag );
1786
is_ICC_signature_char(png_alloc_size_t it)
1788
return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) ||
1789
(it >= 97 && it <= 122);
1793
is_ICC_signature(png_alloc_size_t it)
1795
return is_ICC_signature_char(it >> 24) /* checks all the top bits */ &&
1796
is_ICC_signature_char((it >> 16) & 0xff) &&
1797
is_ICC_signature_char((it >> 8) & 0xff) &&
1798
is_ICC_signature_char(it & 0xff);
1802
png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
1803
png_const_charp name, png_alloc_size_t value, png_const_charp reason)
1806
char message[196]; /* see below for calculation */
1808
if (colorspace != NULL)
1809
colorspace->flags |= PNG_COLORSPACE_INVALID;
1811
pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
1812
pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
1813
pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
1814
if (is_ICC_signature(value) != 0)
1816
/* So 'value' is at most 4 bytes and the following cast is safe */
1817
png_icc_tag_name(message+pos, (png_uint_32)value);
1818
pos += 6; /* total +8; less than the else clause */
1819
message[pos++] = ':';
1820
message[pos++] = ' ';
1822
# ifdef PNG_WARNINGS_SUPPORTED
1825
char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114 */
1827
pos = png_safecat(message, (sizeof message), pos,
1828
png_format_number(number, number+(sizeof number),
1829
PNG_NUMBER_FORMAT_x, value));
1830
pos = png_safecat(message, (sizeof message), pos, "h: "); /* +2 = 116 */
1833
/* The 'reason' is an arbitrary message, allow +79 maximum 195 */
1834
pos = png_safecat(message, (sizeof message), pos, reason);
1837
/* This is recoverable, but make it unconditionally an app_error on write to
1838
* avoid writing invalid ICC profiles into PNG files (i.e., we handle them
1839
* on read, with a warning, but on write unless the app turns off
1840
* application errors the PNG won't be written.)
1842
png_chunk_report(png_ptr, message,
1843
(colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
1847
#endif /* sRGB || iCCP */
1849
#ifdef PNG_sRGB_SUPPORTED
1851
png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
1854
/* sRGB sets known gamma, end points and (from the chunk) intent. */
1855
/* IMPORTANT: these are not necessarily the values found in an ICC profile
1856
* because ICC profiles store values adapted to a D50 environment; it is
1857
* expected that the ICC profile mediaWhitePointTag will be D50; see the
1858
* checks and code elsewhere to understand this better.
1860
* These XYZ values, which are accurate to 5dp, produce rgb to gray
1861
* coefficients of (6968,23435,2366), which are reduced (because they add up
1862
* to 32769 not 32768) to (6968,23434,2366). These are the values that
1863
* libpng has traditionally used (and are the best values given the 15bit
1864
* algorithm used by the rgb to gray code.)
1866
static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */
1869
/* red */ 41239, 21264, 1933,
1870
/* green */ 35758, 71517, 11919,
1871
/* blue */ 18048, 7219, 95053
1874
/* Do nothing if the colorspace is already invalidated. */
1875
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
1878
/* Check the intent, then check for existing settings. It is valid for the
1879
* PNG file to have cHRM or gAMA chunks along with sRGB, but the values must
1880
* be consistent with the correct values. If, however, this function is
1881
* called below because an iCCP chunk matches sRGB then it is quite
1882
* conceivable that an older app recorded incorrect gAMA and cHRM because of
1883
* an incorrect calculation based on the values in the profile - this does
1884
* *not* invalidate the profile (though it still produces an error, which can
1887
if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
1888
return png_icc_profile_error(png_ptr, colorspace, "sRGB",
1889
(png_alloc_size_t)intent, "invalid sRGB rendering intent");
1891
if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
1892
colorspace->rendering_intent != intent)
1893
return png_icc_profile_error(png_ptr, colorspace, "sRGB",
1894
(png_alloc_size_t)intent, "inconsistent rendering intents");
1896
if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
1898
png_benign_error(png_ptr, "duplicate sRGB information ignored");
1902
/* If the standard sRGB cHRM chunk does not match the one from the PNG file
1903
* warn but overwrite the value with the correct one.
1905
if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 &&
1906
!png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
1908
png_chunk_report(png_ptr, "cHRM chunk does not match sRGB",
1911
/* This check is just done for the error reporting - the routine always
1912
* returns true when the 'from' argument corresponds to sRGB (2).
1914
(void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE,
1917
/* intent: bugs in GCC force 'int' to be used as the parameter type. */
1918
colorspace->rendering_intent = (png_uint_16)intent;
1919
colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT;
1922
colorspace->end_points_xy = sRGB_xy;
1923
colorspace->end_points_XYZ = sRGB_XYZ;
1924
colorspace->flags |=
1925
(PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
1928
colorspace->gamma = PNG_GAMMA_sRGB_INVERSE;
1929
colorspace->flags |= PNG_COLORSPACE_HAVE_GAMMA;
1931
/* Finally record that we have an sRGB profile */
1932
colorspace->flags |=
1933
(PNG_COLORSPACE_MATCHES_sRGB|PNG_COLORSPACE_FROM_sRGB);
1939
#ifdef PNG_iCCP_SUPPORTED
1940
/* Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value
1941
* is XYZ(0.9642,1.0,0.8249), which scales to:
1943
* (63189.8112, 65536, 54060.6464)
1945
static const png_byte D50_nCIEXYZ[12] =
1946
{ 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };1948
static int /* bool */
1949
icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
1950
png_const_charp name, png_uint_32 profile_length)
1952
if (profile_length < 132)
1953
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
1958
#ifdef PNG_READ_iCCP_SUPPORTED
1960
png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
1961
png_const_charp name, png_uint_32 profile_length)
1963
if (!icc_check_length(png_ptr, colorspace, name, profile_length))
1966
/* This needs to be here because the 'normal' check is in
1967
* png_decompress_chunk, yet this happens after the attempt to
1968
* png_malloc_base the required data. We only need this on read; on write
1969
* the caller supplies the profile buffer so libpng doesn't allocate it. See
1970
* the call to icc_check_length below (the write case).
1972
# ifdef PNG_SET_USER_LIMITS_SUPPORTED
1973
else if (png_ptr->user_chunk_malloc_max > 0 &&
1974
png_ptr->user_chunk_malloc_max < profile_length)
1975
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
1976
"exceeds application limits");
1977
# elif PNG_USER_CHUNK_MALLOC_MAX > 0
1978
else if (PNG_USER_CHUNK_MALLOC_MAX < profile_length)
1979
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
1980
"exceeds libpng limits");
1981
# else /* !SET_USER_LIMITS */
1982
/* This will get compiled out on all 32-bit and better systems. */
1983
else if (PNG_SIZE_MAX < profile_length)
1984
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
1985
"exceeds system limits");
1986
# endif /* !SET_USER_LIMITS */
1990
#endif /* READ_iCCP */
1993
png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
1994
png_const_charp name, png_uint_32 profile_length,
1995
png_const_bytep profile/* first 132 bytes only */, int color_type)
1999
/* Length check; this cannot be ignored in this code because profile_length
2000
* is used later to check the tag table, so even if the profile seems over
2001
* long profile_length from the caller must be correct. The caller can fix
2002
* this up on read or write by just passing in the profile header length.
2004
temp = png_get_uint_32(profile);
2005
if (temp != profile_length)
2006
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2007
"length does not match profile");
2009
temp = (png_uint_32) (*(profile+8));
2010
if (temp > 3 && (profile_length & 3))
2011
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
2014
temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
2015
if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
2016
profile_length < 132+12*temp) /* truncated tag table */
2017
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2018
"tag count too large");
2020
/* The 'intent' must be valid or we can't store it, ICC limits the intent to
2023
temp = png_get_uint_32(profile+64);
2024
if (temp >= 0xffff) /* The ICC limit */
2025
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2026
"invalid rendering intent");
2028
/* This is just a warning because the profile may be valid in future
2031
if (temp >= PNG_sRGB_INTENT_LAST)
2032
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
2033
"intent outside defined range");
2035
/* At this point the tag table can't be checked because it hasn't necessarily
2036
* been loaded; however, various header fields can be checked. These checks
2037
* are for values permitted by the PNG spec in an ICC profile; the PNG spec
2038
* restricts the profiles that can be passed in an iCCP chunk (they must be
2039
* appropriate to processing PNG data!)
2042
/* Data checks (could be skipped). These checks must be independent of the
2043
* version number; however, the version number doesn't accommodate changes in
2044
* the header fields (just the known tags and the interpretation of the
2047
temp = png_get_uint_32(profile+36); /* signature 'ascp' */
2048
if (temp != 0x61637370)
2049
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2050
"invalid signature");
2052
/* Currently the PCS illuminant/adopted white point (the computational
2053
* white point) are required to be D50,
2054
* however the profile contains a record of the illuminant so perhaps ICC
2055
* expects to be able to change this in the future (despite the rationale in
2056
* the introduction for using a fixed PCS adopted white.) Consequently the
2057
* following is just a warning.
2059
if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
2060
(void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
2061
"PCS illuminant is not D50");
2063
/* The PNG spec requires this:
2064
* "If the iCCP chunk is present, the image samples conform to the colour
2065
* space represented by the embedded ICC profile as defined by the
2066
* International Color Consortium [ICC]. The colour space of the ICC profile
2067
* shall be an RGB colour space for colour images (PNG colour types 2, 3, and
2068
* 6), or a greyscale colour space for greyscale images (PNG colour types 0
2071
* This checking code ensures the embedded profile (on either read or write)
2072
* conforms to the specification requirements. Notice that an ICC 'gray'
2073
* color-space profile contains the information to transform the monochrome
2074
* data to XYZ or L*a*b (according to which PCS the profile uses) and this
2075
* should be used in preference to the standard libpng K channel replication
2076
* into R, G and B channels.
2078
* Previously it was suggested that an RGB profile on grayscale data could be
2079
* handled. However it it is clear that using an RGB profile in this context
2080
* must be an error - there is no specification of what it means. Thus it is
2081
* almost certainly more correct to ignore the profile.
2083
temp = png_get_uint_32(profile+16); /* data colour space field */
2086
case 0x52474220: /* 'RGB ' */
2087
if ((color_type & PNG_COLOR_MASK_COLOR) == 0)
2088
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2089
"RGB color space not permitted on grayscale PNG");
2092
case 0x47524159: /* 'GRAY' */
2093
if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
2094
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2095
"Gray color space not permitted on RGB PNG");
2099
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2100
"invalid ICC profile color space");
2103
/* It is up to the application to check that the profile class matches the
2104
* application requirements; the spec provides no guidance, but it's pretty
2105
* weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer2106
* ('prtr') or 'spac' (for generic color spaces). Issue a warning in these2107
* cases. Issue an error for device link or abstract profiles - these don't
2108
* contain the records necessary to transform the color-space to anything
2109
* other than the target device (and not even that for an abstract profile).
2110
* Profiles of these classes may not be embedded in images.
2112
temp = png_get_uint_32(profile+12); /* profile/device class */
2115
case 0x73636e72: /* 'scnr' */
2116
case 0x6d6e7472: /* 'mntr' */
2117
case 0x70727472: /* 'prtr' */
2118
case 0x73706163: /* 'spac' */
2122
case 0x61627374: /* 'abst' */
2123
/* May not be embedded in an image */
2124
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2125
"invalid embedded Abstract ICC profile");
2127
case 0x6c696e6b: /* 'link' */
2128
/* DeviceLink profiles cannot be interpreted in a non-device specific
2129
* fashion, if an app uses the AToB0Tag in the profile the results are
2130
* undefined unless the result is sent to the intended device,
2131
* therefore a DeviceLink profile should not be found embedded in a
2134
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2135
"unexpected DeviceLink ICC profile class");
2137
case 0x6e6d636c: /* 'nmcl' */
2138
/* A NamedColor profile is also device specific, however it doesn't
2139
* contain an AToB0 tag that is open to misinterpretation. Almost
2140
* certainly it will fail the tests below.
2142
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
2143
"unexpected NamedColor ICC profile class");
2147
/* To allow for future enhancements to the profile accept unrecognized
2148
* profile classes with a warning, these then hit the test below on the
2149
* tag content to ensure they are backward compatible with one of the
2150
* understood profiles.
2152
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
2153
"unrecognized ICC profile class");
2157
/* For any profile other than a device link one the PCS must be encoded
2158
* either in XYZ or Lab.
2160
temp = png_get_uint_32(profile+20);
2163
case 0x58595a20: /* 'XYZ ' */
2164
case 0x4c616220: /* 'Lab ' */
2168
return png_icc_profile_error(png_ptr, colorspace, name, temp,
2169
"unexpected ICC PCS encoding");
2176
png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
2177
png_const_charp name, png_uint_32 profile_length,
2178
png_const_bytep profile /* header plus whole tag table */)
2180
png_uint_32 tag_count = png_get_uint_32(profile+128);
2182
png_const_bytep tag = profile+132; /* The first tag */
2184
/* First scan all the tags in the table and add bits to the icc_info value
2185
* (temporarily in 'tags').
2187
for (itag=0; itag < tag_count; ++itag, tag += 12)
2189
png_uint_32 tag_id = png_get_uint_32(tag+0);
2190
png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */
2191
png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */
2193
/* The ICC specification does not exclude zero length tags, therefore the
2194
* start might actually be anywhere if there is no data, but this would be
2195
* a clear abuse of the intent of the standard so the start is checked for
2196
* being in range. All defined tag types have an 8 byte header - a 4 byte
2197
* type signature then 0.
2200
/* This is a hard error; potentially it can cause read outside the
2203
if (tag_start > profile_length || tag_length > profile_length - tag_start)
2204
return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
2205
"ICC profile tag outside profile");
2207
if ((tag_start & 3) != 0)
2209
/* CNHP730S.icc shipped with Microsoft Windows 64 violates this; it is
2210
* only a warning here because libpng does not care about the
2213
(void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
2214
"ICC profile tag start not a multiple of 4");
2218
return 1; /* success, maybe with warnings */
2221
#ifdef PNG_sRGB_SUPPORTED
2222
#if PNG_sRGB_PROFILE_CHECKS >= 0
2223
/* Information about the known ICC sRGB profiles */
2226
png_uint_32 adler, crc, length;
2232
# define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0)2233
# define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\
2234
{ adler, crc, length, md5, broke, intent },2236
} png_sRGB_checks[] =
2238
/* This data comes from contrib/tools/checksum-icc run on downloads of
2239
* all four ICC sRGB profiles from www.color.org.
2241
/* adler32, crc32, MD5[4], intent, date, length, file-name */
2242
PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
2243
PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
2244
"2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
2246
/* ICC sRGB v2 perceptual no black-compensation: */
2247
PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21,
2248
PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
2249
"2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")
2251
PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae,
2252
PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
2253
"2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")
2255
/* ICC sRGB v4 perceptual */
2256
PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812,
2257
PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
2258
"2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")
2260
/* The following profiles have no known MD5 checksum. If there is a match
2261
* on the (empty) MD5 the other fields are used to attempt a match and
2262
* a warning is produced. The first two of these profiles have a 'cprt' tag
2263
* which suggests that they were also made by Hewlett Packard.
2265
PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce,
2266
PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
2267
"2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")
2269
/* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not
2270
* match the D50 PCS illuminant in the header (it is in fact the D65 values,
2271
* so the white point is recorded as the un-adapted value.) The profiles
2272
* below only differ in one byte - the intent - and are basically the same as
2273
* the previous profile except for the mediaWhitePointTag error and a missing
2274
* chromaticAdaptationTag.
2276
PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
2277
PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
2278
"1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
2280
PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
2281
PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
2282
"1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
2286
png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
2287
png_const_bytep profile, uLong adler)
2289
/* The quick check is to verify just the MD5 signature and trust the
2290
* rest of the data. Because the profile has already been verified for
2291
* correctness this is safe. png_colorspace_set_sRGB will check the 'intent'
2292
* field too, so if the profile has been edited with an intent not defined
2293
* by sRGB (but maybe defined by a later ICC specification) the read of
2294
* the profile will fail at that point.
2297
png_uint_32 length = 0;
2298
png_uint_32 intent = 0x10000; /* invalid */
2299
#if PNG_sRGB_PROFILE_CHECKS > 1
2300
uLong crc = 0; /* the value for 0 length data */
2304
#ifdef PNG_SET_OPTION_SUPPORTED
2305
/* First see if PNG_SKIP_sRGB_CHECK_PROFILE has been set to "on" */
2306
if (((png_ptr->options >> PNG_SKIP_sRGB_CHECK_PROFILE) & 3) ==
2311
for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i)
2313
if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] &&
2314
png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] &&
2315
png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] &&
2316
png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3])
2318
/* This may be one of the old HP profiles without an MD5, in that
2319
* case we can only use the length and Adler32 (note that these
2320
* are not used by default if there is an MD5!)
2322
# if PNG_sRGB_PROFILE_CHECKS == 0
2323
if (png_sRGB_checks[i].have_md5 != 0)
2324
return 1+png_sRGB_checks[i].is_broken;
2327
/* Profile is unsigned or more checks have been configured in. */
2330
length = png_get_uint_32(profile);
2331
intent = png_get_uint_32(profile+64);
2334
/* Length *and* intent must match */
2335
if (length == (png_uint_32) png_sRGB_checks[i].length &&
2336
intent == (png_uint_32) png_sRGB_checks[i].intent)
2338
/* Now calculate the adler32 if not done already. */
2341
adler = adler32(0, NULL, 0);
2342
adler = adler32(adler, profile, length);
2345
if (adler == png_sRGB_checks[i].adler)
2347
/* These basic checks suggest that the data has not been
2348
* modified, but if the check level is more than 1 perform
2349
* our own crc32 checksum on the data.
2351
# if PNG_sRGB_PROFILE_CHECKS > 1
2354
crc = crc32(0, NULL, 0);
2355
crc = crc32(crc, profile, length);
2358
/* So this check must pass for the 'return' below to happen.
2360
if (crc == png_sRGB_checks[i].crc)
2363
if (png_sRGB_checks[i].is_broken != 0)
2365
/* These profiles are known to have bad data that may cause
2366
* problems if they are used, therefore attempt to
2367
* discourage their use, skip the 'have_md5' warning below,
2368
* which is made irrelevant by this error.
2370
png_chunk_report(png_ptr, "known incorrect sRGB profile",
2374
/* Warn that this being done; this isn't even an error since
2375
* the profile is perfectly valid, but it would be nice if
2376
* people used the up-to-date ones.
2378
else if (png_sRGB_checks[i].have_md5 == 0)
2380
png_chunk_report(png_ptr,
2381
"out-of-date sRGB profile with no signature",
2385
return 1+png_sRGB_checks[i].is_broken;
2389
# if PNG_sRGB_PROFILE_CHECKS > 0
2390
/* The signature matched, but the profile had been changed in some
2391
* way. This probably indicates a data error or uninformed hacking.
2392
* Fall through to "no match".
2394
png_chunk_report(png_ptr,
2395
"Not recognizing known sRGB profile that has been edited",
2403
return 0; /* no match */
2407
png_icc_set_sRGB(png_const_structrp png_ptr,
2408
png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
2410
/* Is this profile one of the known ICC sRGB profiles? If it is, just set
2411
* the sRGB information.
2413
if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
2414
(void)png_colorspace_set_sRGB(png_ptr, colorspace,
2415
(int)/*already checked*/png_get_uint_32(profile+64));
2417
#endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */
2421
png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
2422
png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
2425
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
2428
if (icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
2429
png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
2431
png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
2434
# if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
2435
/* If no sRGB support, don't try storing sRGB information */
2436
png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
2446
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2448
png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
2450
/* Set the rgb_to_gray coefficients from the colorspace. */
2451
if (png_ptr->rgb_to_gray_coefficients_set == 0 &&
2452
(png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
2454
/* png_set_background has not been called, get the coefficients from the Y
2455
* values of the colorspace colorants.
2457
png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
2458
png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
2459
png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
2460
png_fixed_point total = r+g+b;
2463
r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
2464
g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
2465
b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
2468
/* We allow 0 coefficients here. r+g+b may be 32769 if two or
2469
* all of the coefficients were rounded up. Handle this by
2470
* reducing the *largest* coefficient by 1; this matches the
2471
* approach used for the default coefficients in pngrtran.c
2477
else if (r+g+b < 32768)
2482
if (g >= r && g >= b)
2484
else if (r >= g && r >= b)
2490
/* Check for an internal error. */
2493
"internal error handling cHRM coefficients");
2497
png_ptr->rgb_to_gray_red_coeff = (png_uint_16)r;
2498
png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
2502
/* This is a png_error at present even though it could be ignored -
2503
* it should never happen, but it is important that if it does, the
2507
png_error(png_ptr, "internal error handling cHRM->XYZ");
2510
#endif /* READ_RGB_TO_GRAY */
2512
#endif /* COLORSPACE */
2515
png_check_IHDR(png_const_structrp png_ptr,
2516
png_uint_32 width, png_uint_32 height, int bit_depth,
2517
int color_type, int interlace_type, int compression_type,
2522
/* Check for width and height valid values */
2525
png_warning(png_ptr, "Image width is zero in IHDR");
2529
if (width > PNG_UINT_31_MAX)
2531
png_warning(png_ptr, "Invalid image width in IHDR");
2535
/* The bit mask on the first line below must be at least as big as a
2536
* png_uint_32. "~7U" is not adequate on 16-bit systems because it will
2537
* be an unsigned 16-bit value. Casting to (png_alloc_size_t) makes the
2538
* type of the result at least as bit (in bits) as the RHS of the > operator
2539
* which also avoids a common warning on 64-bit systems that the comparison
2540
* of (png_uint_32) against the constant value on the RHS will always be
2543
if (((width + 7) & ~(png_alloc_size_t)7) >
2545
- 48 /* big_row_buf hack */
2546
- 1) /* filter byte */
2547
/ 8) /* 8-byte RGBA pixels */
2548
- 1)) /* extra max_pixel_depth pad */
2550
/* The size of the row must be within the limits of this architecture.
2551
* Because the read code can perform arbitrary transformations the
2552
* maximum size is checked here. Because the code in png_read_start_row
2553
* adds extra space "for safety's sake" in several places a conservative
2554
* limit is used here.
2556
* NOTE: it would be far better to check the size that is actually used,
2557
* but the effect in the real world is minor and the changes are more
2558
* extensive, therefore much more dangerous and much more difficult to
2559
* write in a way that avoids compiler warnings.
2561
png_warning(png_ptr, "Image width is too large for this architecture");
2565
#ifdef PNG_SET_USER_LIMITS_SUPPORTED
2566
if (width > png_ptr->user_width_max)
2568
if (width > PNG_USER_WIDTH_MAX)
2571
png_warning(png_ptr, "Image width exceeds user limit in IHDR");
2577
png_warning(png_ptr, "Image height is zero in IHDR");
2581
if (height > PNG_UINT_31_MAX)
2583
png_warning(png_ptr, "Invalid image height in IHDR");
2587
#ifdef PNG_SET_USER_LIMITS_SUPPORTED
2588
if (height > png_ptr->user_height_max)
2590
if (height > PNG_USER_HEIGHT_MAX)
2593
png_warning(png_ptr, "Image height exceeds user limit in IHDR");
2597
/* Check other values */
2598
if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
2599
bit_depth != 8 && bit_depth != 16)
2601
png_warning(png_ptr, "Invalid bit depth in IHDR");
2605
if (color_type < 0 || color_type == 1 ||
2606
color_type == 5 || color_type > 6)
2608
png_warning(png_ptr, "Invalid color type in IHDR");
2612
if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
2613
((color_type == PNG_COLOR_TYPE_RGB ||
2614
color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
2615
color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
2617
png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR");
2621
if (interlace_type >= PNG_INTERLACE_LAST)
2623
png_warning(png_ptr, "Unknown interlace method in IHDR");
2627
if (compression_type != PNG_COMPRESSION_TYPE_BASE)
2629
png_warning(png_ptr, "Unknown compression method in IHDR");
2633
#ifdef PNG_MNG_FEATURES_SUPPORTED
2634
/* Accept filter_method 64 (intrapixel differencing) only if
2635
* 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
2636
* 2. Libpng did not read a PNG signature (this filter_method is only
2637
* used in PNG datastreams that are embedded in MNG datastreams) and
2638
* 3. The application called png_permit_mng_features with a mask that
2639
* included PNG_FLAG_MNG_FILTER_64 and
2640
* 4. The filter_method is 64 and
2641
* 5. The color_type is RGB or RGBA
2643
if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 &&
2644
png_ptr->mng_features_permitted != 0)
2645
png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
2647
if (filter_type != PNG_FILTER_TYPE_BASE)
2649
if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
2650
(filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
2651
((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
2652
(color_type == PNG_COLOR_TYPE_RGB ||
2653
color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
2655
png_warning(png_ptr, "Unknown filter method in IHDR");
2659
if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0)
2661
png_warning(png_ptr, "Invalid filter method in IHDR");
2667
if (filter_type != PNG_FILTER_TYPE_BASE)
2669
png_warning(png_ptr, "Unknown filter method in IHDR");
2675
png_error(png_ptr, "Invalid IHDR data");
2678
#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
2679
/* ASCII to fp functions */
2680
/* Check an ASCII formatted floating point value, see the more detailed
2681
* comments in pngpriv.h
2683
/* The following is used internally to preserve the sticky flags */
2684
#define png_fp_add(state, flags) ((state) |= (flags))
2685
#define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY))
2688
png_check_fp_number(png_const_charp string, size_t size, int *statep,
2691
int state = *statep;
2692
size_t i = *whereami;
2697
/* First find the type of the next character */
2700
case 43: type = PNG_FP_SAW_SIGN; break;
2701
case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break;
2702
case 46: type = PNG_FP_SAW_DOT; break;
2703
case 48: type = PNG_FP_SAW_DIGIT; break;
2704
case 49: case 50: case 51: case 52:
2705
case 53: case 54: case 55: case 56:
2706
case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break;
2708
case 101: type = PNG_FP_SAW_E; break;
2709
default: goto PNG_FP_End;
2712
/* Now deal with this type according to the current
2713
* state, the type is arranged to not overlap the
2714
* bits of the PNG_FP_STATE.
2716
switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
2718
case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
2719
if ((state & PNG_FP_SAW_ANY) != 0)
2720
goto PNG_FP_End; /* not a part of the number */
2722
png_fp_add(state, type);
2725
case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
2726
/* Ok as trailer, ok as lead of fraction. */
2727
if ((state & PNG_FP_SAW_DOT) != 0) /* two dots */
2730
else if ((state & PNG_FP_SAW_DIGIT) != 0) /* trailing dot? */
2731
png_fp_add(state, type);
2734
png_fp_set(state, PNG_FP_FRACTION | type);
2738
case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
2739
if ((state & PNG_FP_SAW_DOT) != 0) /* delayed fraction */
2740
png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);
2742
png_fp_add(state, type | PNG_FP_WAS_VALID);
2746
case PNG_FP_INTEGER + PNG_FP_SAW_E:
2747
if ((state & PNG_FP_SAW_DIGIT) == 0)
2750
png_fp_set(state, PNG_FP_EXPONENT);
2754
/* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN:
2755
goto PNG_FP_End; ** no sign in fraction */
2757
/* case PNG_FP_FRACTION + PNG_FP_SAW_DOT:
2758
goto PNG_FP_End; ** Because SAW_DOT is always set */
2760
case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT:
2761
png_fp_add(state, type | PNG_FP_WAS_VALID);
2764
case PNG_FP_FRACTION + PNG_FP_SAW_E:
2765
/* This is correct because the trailing '.' on an
2766
* integer is handled above - so we can only get here
2767
* with the sequence ".E" (with no preceding digits).
2769
if ((state & PNG_FP_SAW_DIGIT) == 0)
2772
png_fp_set(state, PNG_FP_EXPONENT);
2776
case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
2777
if ((state & PNG_FP_SAW_ANY) != 0)
2778
goto PNG_FP_End; /* not a part of the number */
2780
png_fp_add(state, PNG_FP_SAW_SIGN);
2784
/* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT:
2787
case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT:
2788
png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID);
2792
/* case PNG_FP_EXPONEXT + PNG_FP_SAW_E:
2795
default: goto PNG_FP_End; /* I.e. break 2 */
2798
/* The character seems ok, continue. */
2803
/* Here at the end, update the state and return the correct
2809
return (state & PNG_FP_SAW_DIGIT) != 0;
2813
/* The same but for a complete string. */
2815
png_check_fp_string(png_const_charp string, size_t size)
2818
size_t char_index=0;
2820
if (png_check_fp_number(string, size, &state, &char_index) != 0 &&
2821
(char_index == size || string[char_index] == 0))
2822
return state /* must be non-zero - see above */;
2824
return 0; /* i.e. fail */
2826
#endif /* pCAL || sCAL */
2828
#ifdef PNG_sCAL_SUPPORTED
2829
# ifdef PNG_FLOATING_POINT_SUPPORTED
2830
/* Utility used below - a simple accurate power of ten from an integral
2839
/* Handle negative exponent with a reciprocal at the end because
2840
* 10 is exact whereas .1 is inexact in base 2
2844
if (power < DBL_MIN_10_EXP) return 0;
2845
recip = 1; power = -power;
2850
/* Decompose power bitwise. */
2854
if (power & 1) d *= mult;
2860
if (recip != 0) d = 1/d;
2862
/* else power is 0 and d is 1 */
2867
/* Function to format a floating point value in ASCII with a given
2871
png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, size_t size,
2872
double fp, unsigned int precision)
2874
/* We use standard functions from math.h, but not printf because
2875
* that would require stdio. The caller must supply a buffer of
2876
* sufficient size or we will png_error. The tests on size and
2877
* the space in ascii[] consumed are indicated below.
2880
precision = DBL_DIG;
2882
/* Enforce the limit of the implementation precision too. */
2883
if (precision > DBL_DIG+1)
2884
precision = DBL_DIG+1;
2886
/* Basic sanity checks */
2887
if (size >= precision+5) /* See the requirements below. */
2892
*ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */
2896
if (fp >= DBL_MIN && fp <= DBL_MAX)
2898
int exp_b10; /* A base 10 exponent */
2899
double base; /* 10^exp_b10 */
2901
/* First extract a base 10 exponent of the number,
2902
* the calculation below rounds down when converting
2903
* from base 2 to base 10 (multiply by log10(2) -
2904
* 0.3010, but 77/256 is 0.3008, so exp_b10 needs to
2905
* be increased. Note that the arithmetic shift
2906
* performs a floor() unlike C arithmetic - using a
2907
* C multiply would break the following for negative
2910
(void)frexp(fp, &exp_b10); /* exponent to base 2 */
2912
exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */
2914
/* Avoid underflow here. */
2915
base = png_pow10(exp_b10); /* May underflow */
2917
while (base < DBL_MIN || base < fp)
2919
/* And this may overflow. */
2920
double test = png_pow10(exp_b10+1);
2922
if (test <= DBL_MAX)
2924
++exp_b10; base = test;
2931
/* Normalize fp and correct exp_b10, after this fp is in the
2932
* range [.1,1) and exp_b10 is both the exponent and the digit
2933
* *before* which the decimal point should be inserted
2934
* (starting with 0 for the first digit). Note that this
2935
* works even if 10^exp_b10 is out of range because of the
2936
* test on DBL_MAX above.
2941
fp /= 10; ++exp_b10;
2944
/* Because of the code above fp may, at this point, be
2945
* less than .1, this is ok because the code below can
2946
* handle the leading zeros this generates, so no attempt
2947
* is made to correct that here.
2951
unsigned int czero, clead, cdigits;
2954
/* Allow up to two leading zeros - this will not lengthen
2955
* the number compared to using E-n.
2957
if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */
2959
czero = 0U-exp_b10; /* PLUS 2 digits: TOTAL 3 */
2960
exp_b10 = 0; /* Dot added below before first output. */
2963
czero = 0; /* No zeros to add */
2965
/* Generate the digit list, stripping trailing zeros and
2966
* inserting a '.' before a digit if the exponent is 0.
2968
clead = czero; /* Count of leading zeros */
2969
cdigits = 0; /* Count of digits in list. */
2976
/* Use modf here, not floor and subtract, so that
2977
* the separation is done in one step. At the end
2978
* of the loop don't break the number into parts so
2979
* that the final digit is rounded.
2981
if (cdigits+czero+1 < precision+clead)
2990
/* Rounding up to 10, handle that here. */
2994
if (cdigits == 0) --clead;
2998
while (cdigits > 0 && d > 9)
3002
if (exp_b10 != (-1))
3007
ch = *--ascii; ++size;
3008
/* Advance exp_b10 to '1', so that the
3009
* decimal point happens after the
3016
d = ch - 47; /* I.e. 1+(ch-48) */
3019
/* Did we reach the beginning? If so adjust the
3020
* exponent but take into account the leading
3023
if (d > 9) /* cdigits == 0 */
3025
if (exp_b10 == (-1))
3027
/* Leading decimal point (plus zeros?), if
3028
* we lose the decimal point here it must
3029
* be reentered below.
3035
++size; exp_b10 = 1;
3038
/* Else lost a leading zero, so 'exp_b10' is
3045
/* In all cases we output a '1' */
3050
fp = 0; /* Guarantees termination below. */
3056
if (cdigits == 0) ++clead;
3060
/* Included embedded zeros in the digit count. */
3061
cdigits += czero - clead;
3066
/* exp_b10 == (-1) means we just output the decimal
3067
* place - after the DP don't adjust 'exp_b10' any
3070
if (exp_b10 != (-1))
3074
*ascii++ = 46; --size;
3076
/* PLUS 1: TOTAL 4 */
3079
*ascii++ = 48; --czero;
3082
if (exp_b10 != (-1))
3086
*ascii++ = 46; --size; /* counted above */
3091
*ascii++ = (char)(48 + (int)d); ++cdigits;
3094
while (cdigits+czero < precision+clead && fp > DBL_MIN);
3096
/* The total output count (max) is now 4+precision */
3098
/* Check for an exponent, if we don't need one we are
3099
* done and just need to terminate the string. At this
3100
* point, exp_b10==(-1) is effectively a flag: it got
3101
* to '-1' because of the decrement, after outputting
3102
* the decimal point above. (The exponent required is
3105
if (exp_b10 >= (-1) && exp_b10 <= 2)
3107
/* The following only happens if we didn't output the
3108
* leading zeros above for negative exponent, so this
3109
* doesn't add to the digit requirement. Note that the
3110
* two zeros here can only be output if the two leading
3111
* zeros were *not* output, so this doesn't increase
3114
while (exp_b10-- > 0) *ascii++ = 48;
3118
/* Total buffer requirement (including the '\0') is
3119
* 5+precision - see check at the start.
3124
/* Here if an exponent is required, adjust size for
3125
* the digits we output but did not count. The total
3126
* digit output here so far is at most 1+precision - no
3127
* decimal point and no leading or trailing zeros have
3132
*ascii++ = 69; --size; /* 'E': PLUS 1 TOTAL 2+precision */
3134
/* The following use of an unsigned temporary avoids ambiguities in
3135
* the signed arithmetic on exp_b10 and permits GCC at least to do
3136
* better optimization.
3139
unsigned int uexp_b10;
3143
*ascii++ = 45; --size; /* '-': PLUS 1 TOTAL 3+precision */
3144
uexp_b10 = 0U-exp_b10;
3148
uexp_b10 = 0U+exp_b10;
3152
while (uexp_b10 > 0)
3154
exponent[cdigits++] = (char)(48 + uexp_b10 % 10);
3159
/* Need another size check here for the exponent digits, so
3160
* this need not be considered above.
3164
while (cdigits > 0) *ascii++ = exponent[--cdigits];
3172
else if (!(fp >= DBL_MIN))
3174
*ascii++ = 48; /* '0' */
3180
*ascii++ = 105; /* 'i' */
3181
*ascii++ = 110; /* 'n' */
3182
*ascii++ = 102; /* 'f' */
3188
/* Here on buffer too small. */
3189
png_error(png_ptr, "ASCII conversion buffer too small");
3191
# endif /* FLOATING_POINT */
3193
# ifdef PNG_FIXED_POINT_SUPPORTED
3194
/* Function to format a fixed point value in ASCII.
3197
png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
3198
size_t size, png_fixed_point fp)
3200
/* Require space for 10 decimal digits, a decimal point, a minus sign and a
3201
* trailing \0, 13 characters:
3207
/* Avoid overflow here on the minimum integer. */
3210
*ascii++ = 45; num = (png_uint_32)(-fp);
3213
num = (png_uint_32)fp;
3215
if (num <= 0x80000000) /* else overflowed */
3217
unsigned int ndigits = 0, first = 16 /* flag value */;
3218
char digits[10] = {0};3222
/* Split the low digit off num: */
3223
unsigned int tmp = num/10;
3225
digits[ndigits++] = (char)(48 + num);
3226
/* Record the first non-zero digit, note that this is a number
3227
* starting at 1, it's not actually the array index.
3229
if (first == 16 && num > 0)
3236
while (ndigits > 5) *ascii++ = digits[--ndigits];
3237
/* The remaining digits are fractional digits, ndigits is '5' or
3238
* smaller at this point. It is certainly not zero. Check for a
3239
* non-zero fractional digit:
3244
*ascii++ = 46; /* decimal point */
3245
/* ndigits may be <5 for small numbers, output leading zeros
3246
* then ndigits digits to first:
3253
while (ndigits >= first) *ascii++ = digits[--ndigits];
3254
/* Don't output the trailing zeros! */
3260
/* And null terminate the string: */
3266
/* Here on buffer too small. */
3267
png_error(png_ptr, "ASCII conversion buffer too small");
3269
# endif /* FIXED_POINT */
3272
#if defined(PNG_FLOATING_POINT_SUPPORTED) && \
3273
!defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
3274
(defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
3275
defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
3276
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
3277
(defined(PNG_sCAL_SUPPORTED) && \
3278
defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
3280
png_fixed(png_const_structrp png_ptr, double fp, png_const_charp text)
3282
double r = floor(100000 * fp + .5);
3284
if (r > 2147483647. || r < -2147483648.)
3285
png_fixed_error(png_ptr, text);
3287
# ifndef PNG_ERROR_TEXT_SUPPORTED
3291
return (png_fixed_point)r;
3295
#if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_COLORSPACE_SUPPORTED) ||\
3296
defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
3297
/* muldiv functions */
3298
/* This API takes signed arguments and rounds the result to the nearest
3299
* integer (or, for a fixed point number - the standard argument - to
3300
* the nearest .00001). Overflow and divide by zero are signalled in
3301
* the result, a boolean - true on success, false on overflow.
3304
png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
3307
/* Return a * times / divisor, rounded. */
3310
if (a == 0 || times == 0)
3317
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3323
/* A png_fixed_point is a 32-bit integer. */
3324
if (r <= 2147483647. && r >= -2147483648.)
3326
*res = (png_fixed_point)r;
3331
png_uint_32 A, T, D;
3332
png_uint_32 s16, s32, s00;
3335
negative = 1, A = -a;
3340
negative = !negative, T = -times;
3345
negative = !negative, D = -divisor;
3349
/* Following can't overflow because the arguments only
3350
* have 31 bits each, however the result may be 32 bits.
3352
s16 = (A >> 16) * (T & 0xffff) +
3353
(A & 0xffff) * (T >> 16);
3354
/* Can't overflow because the a*times bit is only 30
3357
s32 = (A >> 16) * (T >> 16) + (s16 >> 16);
3358
s00 = (A & 0xffff) * (T & 0xffff);
3360
s16 = (s16 & 0xffff) << 16;
3366
if (s32 < D) /* else overflow */
3368
/* s32.s00 is now the 64-bit product, do a standard
3369
* division, we know that s32 < D, so the maximum
3370
* required shift is 31.
3373
png_fixed_point result = 0; /* NOTE: signed */
3375
while (--bitshift >= 0)
3377
png_uint_32 d32, d00;
3380
d32 = D >> (32-bitshift), d00 = D << bitshift;
3387
if (s00 < d00) --s32; /* carry */
3388
s32 -= d32, s00 -= d00, result += 1<<bitshift;
3392
if (s32 == d32 && s00 >= d00)
3393
s32 = 0, s00 -= d00, result += 1<<bitshift;
3396
/* Handle the rounding. */
3397
if (s00 >= (D >> 1))
3403
/* Check for overflow. */
3404
if ((negative != 0 && result <= 0) ||
3405
(negative == 0 && result >= 0))
3417
#endif /* READ_GAMMA || INCH_CONVERSIONS */
3419
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
3420
/* The following is for when the caller doesn't much care about the
3424
png_muldiv_warn(png_const_structrp png_ptr, png_fixed_point a, png_int_32 times,
3427
png_fixed_point result;
3429
if (png_muldiv(&result, a, times, divisor) != 0)
3432
png_warning(png_ptr, "fixed point overflow ignored");
3437
#ifdef PNG_GAMMA_SUPPORTED /* more fixed point functions for gamma */
3438
/* Calculate a reciprocal, return 0 on div-by-zero or overflow. */
3440
png_reciprocal(png_fixed_point a)
3442
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3443
double r = floor(1E10/a+.5);
3445
if (r <= 2147483647. && r >= -2147483648.)
3446
return (png_fixed_point)r;
3448
png_fixed_point res;
3450
if (png_muldiv(&res, 100000, 100000, a) != 0)
3454
return 0; /* error/overflow */
3457
/* This is the shared test on whether a gamma value is 'significant' - whether
3458
* it is worth doing gamma correction.
3461
png_gamma_significant(png_fixed_point gamma_val)
3463
return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
3464
gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
3468
#ifdef PNG_READ_GAMMA_SUPPORTED
3469
#ifdef PNG_16BIT_SUPPORTED
3470
/* A local convenience routine. */
3471
static png_fixed_point
3472
png_product2(png_fixed_point a, png_fixed_point b)
3474
/* The required result is 1/a * 1/b; the following preserves accuracy. */
3475
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3476
double r = a * 1E-5;
3480
if (r <= 2147483647. && r >= -2147483648.)
3481
return (png_fixed_point)r;
3483
png_fixed_point res;
3485
if (png_muldiv(&res, a, b, 100000) != 0)
3489
return 0; /* overflow */
3493
/* The inverse of the above. */
3495
png_reciprocal2(png_fixed_point a, png_fixed_point b)
3497
/* The required result is 1/a * 1/b; the following preserves accuracy. */
3498
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3499
if (a != 0 && b != 0)
3505
if (r <= 2147483647. && r >= -2147483648.)
3506
return (png_fixed_point)r;
3509
/* This may overflow because the range of png_fixed_point isn't symmetric,
3510
* but this API is only used for the product of file and screen gamma so it
3511
* doesn't matter that the smallest number it can produce is 1/21474, not
3514
png_fixed_point res = png_product2(a, b);
3517
return png_reciprocal(res);
3520
return 0; /* overflow */
3522
#endif /* READ_GAMMA */
3524
#ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */
3525
#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
3526
/* Fixed point gamma.
3528
* The code to calculate the tables used below can be found in the shell script
3529
* contrib/tools/intgamma.sh
3531
* To calculate gamma this code implements fast log() and exp() calls using only
3532
* fixed point arithmetic. This code has sufficient precision for either 8-bit
3533
* or 16-bit sample values.
3535
* The tables used here were calculated using simple 'bc' programs, but C double
3536
* precision floating point arithmetic would work fine.
3539
* This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
3540
* 255, so it's the base 2 logarithm of a normalized 8-bit floating point
3541
* mantissa. The numbers are 32-bit fractions.
3543
static const png_uint_32
3546
4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U,
3547
3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U,
3548
3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U,
3549
3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U,
3550
3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U,
3551
2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U,
3552
2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U,
3553
2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U,
3554
2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U,
3555
2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U,
3556
1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U,
3557
1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U,
3558
1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U,
3559
1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U,
3560
1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U,
3561
971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U,
3562
803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U,
3563
639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U,
3564
479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U,
3565
324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U,
3566
172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U,
3570
/* The following are the values for 16-bit tables - these work fine for the
3571
* 8-bit conversions but produce very slightly larger errors in the 16-bit
3572
* log (about 1.2 as opposed to 0.7 absolute error in the final value). To
3573
* use these all the shifts below must be adjusted appropriately.
3575
65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054,
3576
57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803,
3577
50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068,
3578
43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782,
3579
37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887,
3580
31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339,
3581
25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098,
3582
20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132,
3583
15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415,
3584
10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523,
3585
6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495,
3591
png_log8bit(unsigned int x)
3593
unsigned int lg2 = 0;
3594
/* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log,
3595
* because the log is actually negate that means adding 1. The final
3596
* returned value thus has the range 0 (for 255 input) to 7.994 (for 1
3597
* input), return -1 for the overflow (log 0) case, - so the result is
3598
* always at most 19 bits.
3600
if ((x &= 0xff) == 0)
3603
if ((x & 0xf0) == 0)
3606
if ((x & 0xc0) == 0)
3609
if ((x & 0x80) == 0)
3612
/* result is at most 19 bits, so this cast is safe: */
3613
return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16));
3616
/* The above gives exact (to 16 binary places) log2 values for 8-bit images,
3617
* for 16-bit images we use the most significant 8 bits of the 16-bit value to
3618
* get an approximation then multiply the approximation by a correction factor
3619
* determined by the remaining up to 8 bits. This requires an additional step
3620
* in the 16-bit case.
3622
* We want log2(value/65535), we have log2(v'/255), where:
3624
* value = v' * 256 + v''
3627
* So f is value/v', which is equal to (256+v''/v') since v' is in the range 128
3628
* to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less
3629
* than 258. The final factor also needs to correct for the fact that our 8-bit
3630
* value is scaled by 255, whereas the 16-bit values must be scaled by 65535.
3632
* This gives a final formula using a calculated value 'x' which is value/v' and
3633
* scaling by 65536 to match the above table:
3635
* log2(x/257) * 65536
3637
* Since these numbers are so close to '1' we can use simple linear
3638
* interpolation between the two end values 256/257 (result -368.61) and 258/257
3639
* (result 367.179). The values used below are scaled by a further 64 to give
3640
* 16-bit precision in the interpolation:
3642
* Start (256): -23591
3646
#ifdef PNG_16BIT_SUPPORTED
3648
png_log16bit(png_uint_32 x)
3650
unsigned int lg2 = 0;
3652
/* As above, but now the input has 16 bits. */
3653
if ((x &= 0xffff) == 0)
3656
if ((x & 0xff00) == 0)
3659
if ((x & 0xf000) == 0)
3662
if ((x & 0xc000) == 0)
3665
if ((x & 0x8000) == 0)
3668
/* Calculate the base logarithm from the top 8 bits as a 28-bit fractional
3672
lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4;
3674
/* Now we need to interpolate the factor, this requires a division by the top
3675
* 8 bits. Do this with maximum precision.
3677
x = ((x << 16) + (x >> 9)) / (x >> 8);
3679
/* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24,
3680
* the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly
3681
* 16 bits to interpolate to get the low bits of the result. Round the
3682
* answer. Note that the end point values are scaled by 64 to retain overall
3683
* precision and that 'lg2' is current scaled by an extra 12 bits, so adjust
3684
* the overall scaling by 6-12. Round at every step.
3688
if (x <= 65536U) /* <= '257' */
3689
lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12);
3692
lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12);
3694
/* Safe, because the result can't have more than 20 bits: */
3695
return (png_int_32)((lg2 + 2048) >> 12);
3699
/* The 'exp()' case must invert the above, taking a 20-bit fixed point
3700
* logarithmic value and returning a 16 or 8-bit number as appropriate. In
3701
* each case only the low 16 bits are relevant - the fraction - since the
3702
* integer bits (the top 4) simply determine a shift.
3704
* The worst case is the 16-bit distinction between 65535 and 65534. This
3705
* requires perhaps spurious accuracy in the decoding of the logarithm to
3706
* distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
3707
* of getting this accuracy in practice.
3709
* To deal with this the following exp() function works out the exponent of the
3710
* fractional part of the logarithm by using an accurate 32-bit value from the
3711
* top four fractional bits then multiplying in the remaining bits.
3713
static const png_uint_32
3716
/* NOTE: the first entry is deliberately set to the maximum 32-bit value. */
3717
4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U,
3718
3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U,
3719
2553802834U, 2445529972U, 2341847524U, 2242560872U
3722
/* Adjustment table; provided to explain the numbers in the code below. */
3724
for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}3725
11 44937.64284865548751208448
3726
10 45180.98734845585101160448
3727
9 45303.31936980687359311872
3728
8 45364.65110595323018870784
3729
7 45395.35850361789624614912
3730
6 45410.72259715102037508096
3731
5 45418.40724413220722311168
3732
4 45422.25021786898173001728
3733
3 45424.17186732298419044352
3734
2 45425.13273269940811464704
3735
1 45425.61317555035558641664
3736
0 45425.85339951654943850496
3740
png_exp(png_fixed_point x)
3742
if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
3744
/* Obtain a 4-bit approximation */
3745
png_uint_32 e = png_32bit_exp[(x >> 12) & 0x0f];
3747
/* Incorporate the low 12 bits - these decrease the returned value by
3748
* multiplying by a number less than 1 if the bit is set. The multiplier
3749
* is determined by the above table and the shift. Notice that the values
3750
* converge on 45426 and this is used to allow linear interpolation of the
3754
e -= (((e >> 16) * 44938U) + 16U) >> 5;
3757
e -= (((e >> 16) * 45181U) + 32U) >> 6;
3760
e -= (((e >> 16) * 45303U) + 64U) >> 7;
3763
e -= (((e >> 16) * 45365U) + 128U) >> 8;
3766
e -= (((e >> 16) * 45395U) + 256U) >> 9;
3769
e -= (((e >> 16) * 45410U) + 512U) >> 10;
3771
/* And handle the low 6 bits in a single block. */
3772
e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9;
3774
/* Handle the upper bits of x. */
3779
/* Check for overflow */
3781
return png_32bit_exp[0];
3783
/* Else underflow */
3788
png_exp8bit(png_fixed_point lg2)
3790
/* Get a 32-bit value: */
3791
png_uint_32 x = png_exp(lg2);
3793
/* Convert the 32-bit value to 0..255 by multiplying by 256-1. Note that the
3794
* second, rounding, step can't overflow because of the first, subtraction,
3798
return (png_byte)(((x + 0x7fffffU) >> 24) & 0xff);
3801
#ifdef PNG_16BIT_SUPPORTED
3803
png_exp16bit(png_fixed_point lg2)
3805
/* Get a 32-bit value: */
3806
png_uint_32 x = png_exp(lg2);
3808
/* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */
3810
return (png_uint_16)((x + 32767U) >> 16);
3813
#endif /* FLOATING_ARITHMETIC */
3816
png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
3818
if (value > 0 && value < 255)
3820
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3821
/* 'value' is unsigned, ANSI-C90 requires the compiler to correctly
3822
* convert this to a floating point value. This includes values that
3823
* would overflow if 'value' were to be converted to 'int'.
3825
* Apparently GCC, however, does an intermediate conversion to (int)
3826
* on some (ARM) but not all (x86) platforms, possibly because of
3827
* hardware FP limitations. (E.g. if the hardware conversion always
3828
* assumes the integer register contains a signed value.) This results
3829
* in ANSI-C undefined behavior for large values.
3831
* Other implementations on the same machine might actually be ANSI-C90
3832
* conformant and therefore compile spurious extra code for the large
3835
* We can be reasonably sure that an unsigned to float conversion
3836
* won't be faster than an int to float one. Therefore this code
3837
* assumes responsibility for the undefined behavior, which it knows
3838
* can't happen because of the check above.
3840
* Note the argument to this routine is an (unsigned int) because, on
3841
* 16-bit platforms, it is assigned a value which might be out of
3842
* range for an (int); that would result in undefined behavior in the
3843
* caller if the *argument* ('value') were to be declared (int).3845
double r = floor(255*pow((int)/*SAFE*/value/255.,gamma_val*.00001)+.5);
3848
png_int_32 lg2 = png_log8bit(value);
3849
png_fixed_point res;
3851
if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
3852
return png_exp8bit(res);
3859
return (png_byte)(value & 0xff);
3862
#ifdef PNG_16BIT_SUPPORTED
3864
png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
3866
if (value > 0 && value < 65535)
3868
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3869
/* The same (unsigned int)->(double) constraints apply here as above,
3870
* however in this case the (unsigned int) to (int) conversion can
3871
* overflow on an ANSI-C90 compliant system so the cast needs to ensure
3872
* that this is not possible.
3874
double r = floor(65535*pow((png_int_32)value/65535.,
3875
gamma_val*.00001)+.5);
3876
return (png_uint_16)r;
3878
png_int_32 lg2 = png_log16bit(value);
3879
png_fixed_point res;
3881
if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
3882
return png_exp16bit(res);
3889
return (png_uint_16)value;
3893
/* This does the right thing based on the bit_depth field of the
3894
* png_struct, interpreting values as 8-bit or 16-bit. While the result
3895
* is nominally a 16-bit value if bit depth is 8 then the result is
3896
* 8-bit (as are the arguments.)
3898
png_uint_16 /* PRIVATE */
3899
png_gamma_correct(png_structrp png_ptr, unsigned int value,
3900
png_fixed_point gamma_val)
3902
if (png_ptr->bit_depth == 8)
3903
return png_gamma_8bit_correct(value, gamma_val);
3905
#ifdef PNG_16BIT_SUPPORTED
3907
return png_gamma_16bit_correct(value, gamma_val);
3909
/* should not reach this */
3914
#ifdef PNG_16BIT_SUPPORTED
3915
/* Internal function to build a single 16-bit table - the table consists of
3916
* 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount
3917
* to shift the input values right (or 16-number_of_signifiant_bits).
3919
* The caller is responsible for ensuring that the table gets cleaned up on
3920
* png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument
3921
* should be somewhere that will be cleaned.
3924
png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
3925
unsigned int shift, png_fixed_point gamma_val)
3927
/* Various values derived from 'shift': */
3928
unsigned int num = 1U << (8U - shift);
3929
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3930
/* CSE the division and work round wacky GCC warnings (see the comments
3931
* in png_gamma_8bit_correct for where these come from.)
3933
double fmax = 1.0 / (((png_int_32)1 << (16U - shift)) - 1);
3935
unsigned int max = (1U << (16U - shift)) - 1U;
3936
unsigned int max_by_2 = 1U << (15U - shift);
3939
png_uint_16pp table = *ptable =
3940
(png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
3942
for (i = 0; i < num; i++)
3944
png_uint_16p sub_table = table[i] =
3945
(png_uint_16p)png_malloc(png_ptr, 256 * (sizeof (png_uint_16)));
3947
/* The 'threshold' test is repeated here because it can arise for one of
3948
* the 16-bit tables even if the others don't hit it.
3950
if (png_gamma_significant(gamma_val) != 0)
3952
/* The old code would overflow at the end and this would cause the
3953
* 'pow' function to return a result >1, resulting in an
3954
* arithmetic error. This code follows the spec exactly; ig is
3955
* the recovered input sample, it always has 8-16 bits.
3957
* We want input * 65535/max, rounded, the arithmetic fits in 32
3958
* bits (unsigned) so long as max <= 32767.
3961
for (j = 0; j < 256; j++)
3963
png_uint_32 ig = (j << (8-shift)) + i;
3964
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
3965
/* Inline the 'max' scaling operation: */
3966
/* See png_gamma_8bit_correct for why the cast to (int) is
3969
double d = floor(65535.*pow(ig*fmax, gamma_val*.00001)+.5);
3970
sub_table[j] = (png_uint_16)d;
3973
ig = (ig * 65535U + max_by_2)/max;
3975
sub_table[j] = png_gamma_16bit_correct(ig, gamma_val);
3981
/* We must still build a table, but do it the fast way. */
3984
for (j = 0; j < 256; j++)
3986
png_uint_32 ig = (j << (8-shift)) + i;
3989
ig = (ig * 65535U + max_by_2)/max;
3991
sub_table[j] = (png_uint_16)ig;
3997
/* NOTE: this function expects the *inverse* of the overall gamma transformation
4001
png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
4002
unsigned int shift, png_fixed_point gamma_val)
4004
unsigned int num = 1U << (8U - shift);
4005
unsigned int max = (1U << (16U - shift))-1U;
4009
png_uint_16pp table = *ptable =
4010
(png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
4012
/* 'num' is the number of tables and also the number of low bits of low
4013
* bits of the input 16-bit value used to select a table. Each table is
4014
* itself indexed by the high 8 bits of the value.
4016
for (i = 0; i < num; i++)
4017
table[i] = (png_uint_16p)png_malloc(png_ptr,
4018
256 * (sizeof (png_uint_16)));
4020
/* 'gamma_val' is set to the reciprocal of the value calculated above, so
4021
* pow(out,g) is an *input* value. 'last' is the last input value set.
4023
* In the loop 'i' is used to find output values. Since the output is
4024
* 8-bit there are only 256 possible values. The tables are set up to
4025
* select the closest possible output value for each input by finding
4026
* the input value at the boundary between each pair of output values
4027
* and filling the table up to that boundary with the lower output
4030
* The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit
4031
* values the code below uses a 16-bit value in i; the values start at
4032
* 128.5 (for 0.5) and step by 257, for a total of 254 values (the last
4033
* entries are filled with 255). Start i at 128 and fill all 'last'
4034
* table entries <= 'max'
4037
for (i = 0; i < 255; ++i) /* 8-bit output value */
4039
/* Find the corresponding maximum input value */
4040
png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */
4042
/* Find the boundary value in 16 bits: */
4043
png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val);
4045
/* Adjust (round) to (16-shift) bits: */
4046
bound = (bound * max + 32768U)/65535U + 1U;
4048
while (last < bound)
4050
table[last & (0xffU >> shift)][last >> (8U - shift)] = out;
4055
/* And fill in the final entries. */
4056
while (last < (num << 8))
4058
table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U;
4064
/* Build a single 8-bit table: same as the 16-bit case but much simpler (and
4065
* typically much faster). Note that libpng currently does no sBIT processing
4066
* (apparently contrary to the spec) so a 256-entry table is always generated.
4069
png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
4070
png_fixed_point gamma_val)
4073
png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
4075
if (png_gamma_significant(gamma_val) != 0)
4076
for (i=0; i<256; i++)
4077
table[i] = png_gamma_8bit_correct(i, gamma_val);
4080
for (i=0; i<256; ++i)
4081
table[i] = (png_byte)(i & 0xff);
4084
/* Used from png_read_destroy and below to release the memory used by the gamma
4088
png_destroy_gamma_table(png_structrp png_ptr)
4090
png_free(png_ptr, png_ptr->gamma_table);
4091
png_ptr->gamma_table = NULL;
4093
#ifdef PNG_16BIT_SUPPORTED
4094
if (png_ptr->gamma_16_table != NULL)
4097
int istop = (1 << (8 - png_ptr->gamma_shift));
4098
for (i = 0; i < istop; i++)
4100
png_free(png_ptr, png_ptr->gamma_16_table[i]);
4102
png_free(png_ptr, png_ptr->gamma_16_table);
4103
png_ptr->gamma_16_table = NULL;
4107
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
4108
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
4109
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
4110
png_free(png_ptr, png_ptr->gamma_from_1);
4111
png_ptr->gamma_from_1 = NULL;
4112
png_free(png_ptr, png_ptr->gamma_to_1);
4113
png_ptr->gamma_to_1 = NULL;
4115
#ifdef PNG_16BIT_SUPPORTED
4116
if (png_ptr->gamma_16_from_1 != NULL)
4119
int istop = (1 << (8 - png_ptr->gamma_shift));
4120
for (i = 0; i < istop; i++)
4122
png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
4124
png_free(png_ptr, png_ptr->gamma_16_from_1);
4125
png_ptr->gamma_16_from_1 = NULL;
4127
if (png_ptr->gamma_16_to_1 != NULL)
4130
int istop = (1 << (8 - png_ptr->gamma_shift));
4131
for (i = 0; i < istop; i++)
4133
png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
4135
png_free(png_ptr, png_ptr->gamma_16_to_1);
4136
png_ptr->gamma_16_to_1 = NULL;
4139
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
4142
/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit
4143
* tables, we don't make a full table if we are reducing to 8-bit in
4144
* the future. Note also how the gamma_16 tables are segmented so that
4145
* we don't need to allocate > 64K chunks for a full 16-bit table.
4148
png_build_gamma_table(png_structrp png_ptr, int bit_depth)
4150
png_debug(1, "in png_build_gamma_table");
4152
/* Remove any existing table; this copes with multiple calls to
4153
* png_read_update_info. The warning is because building the gamma tables
4154
* multiple times is a performance hit - it's harmless but the ability to
4155
* call png_read_update_info() multiple times is new in 1.5.6 so it seems
4156
* sensible to warn if the app introduces such a hit.
4158
if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
4160
png_warning(png_ptr, "gamma table being rebuilt");
4161
png_destroy_gamma_table(png_ptr);
4166
png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
4167
png_ptr->screen_gamma > 0 ?
4168
png_reciprocal2(png_ptr->colorspace.gamma,
4169
png_ptr->screen_gamma) : PNG_FP_1);
4171
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
4172
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
4173
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
4174
if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
4176
png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
4177
png_reciprocal(png_ptr->colorspace.gamma));
4179
png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
4180
png_ptr->screen_gamma > 0 ?
4181
png_reciprocal(png_ptr->screen_gamma) :
4182
png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
4184
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
4186
#ifdef PNG_16BIT_SUPPORTED
4189
png_byte shift, sig_bit;
4191
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
4193
sig_bit = png_ptr->sig_bit.red;
4195
if (png_ptr->sig_bit.green > sig_bit)
4196
sig_bit = png_ptr->sig_bit.green;
4198
if (png_ptr->sig_bit.blue > sig_bit)
4199
sig_bit = png_ptr->sig_bit.blue;
4202
sig_bit = png_ptr->sig_bit.gray;
4204
/* 16-bit gamma code uses this equation:
4206
* ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
4208
* Where 'iv' is the input color value and 'ov' is the output value -
4211
* Thus the gamma table consists of up to 256 256-entry tables. The table
4212
* is selected by the (8-gamma_shift) most significant of the low 8 bits
4213
* of the color value then indexed by the upper 8 bits:
4215
* table[low bits][high 8 bits]
4217
* So the table 'n' corresponds to all those 'iv' of:
4219
* <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
4222
if (sig_bit > 0 && sig_bit < 16U)
4223
/* shift == insignificant bits */
4224
shift = (png_byte)((16U - sig_bit) & 0xff);
4227
shift = 0; /* keep all 16 bits */
4229
if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
4231
/* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
4232
* the significant bits in the *input* when the output will
4233
* eventually be 8 bits. By default it is 11.
4235
if (shift < (16U - PNG_MAX_GAMMA_8))
4236
shift = (16U - PNG_MAX_GAMMA_8);
4240
shift = 8U; /* Guarantees at least one table! */
4242
png_ptr->gamma_shift = shift;
4244
/* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
4245
* PNG_COMPOSE). This effectively smashed the background calculation for
4246
* 16-bit output because the 8-bit table assumes the result will be
4247
* reduced to 8 bits.
4249
if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
4250
png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
4251
png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
4252
png_ptr->screen_gamma) : PNG_FP_1);
4255
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
4256
png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
4257
png_ptr->screen_gamma) : PNG_FP_1);
4259
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
4260
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
4261
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
4262
if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
4264
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
4265
png_reciprocal(png_ptr->colorspace.gamma));
4267
/* Notice that the '16 from 1' table should be full precision, however
4268
* the lookup on this table still uses gamma_shift, so it can't be.
4271
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
4272
png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
4273
png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
4275
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
4279
#endif /* READ_GAMMA */
4281
/* HARDWARE OR SOFTWARE OPTION SUPPORT */
4282
#ifdef PNG_SET_OPTION_SUPPORTED
4284
png_set_option(png_structrp png_ptr, int option, int onoff)
4286
if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
4289
png_uint_32 mask = 3U << option;
4290
png_uint_32 setting = (2U + (onoff != 0)) << option;
4291
png_uint_32 current = png_ptr->options;
4293
png_ptr->options = (png_uint_32)((current & ~mask) | setting);
4295
return (int)(current & mask) >> option;
4298
return PNG_OPTION_INVALID;
4303
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
4304
defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
4305
/* sRGB conversion tables; these are machine generated with the code in
4306
* contrib/tools/makesRGB.c. The actual sRGB transfer curve defined in the
4307
* specification (see the article at https://en.wikipedia.org/wiki/SRGB)
4308
* is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
4309
* The sRGB to linear table is exact (to the nearest 16-bit linear fraction).
4310
* The inverse (linear to sRGB) table has accuracies as follows:
4312
* For all possible (255*65535+1) input values:
4314
* error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact
4316
* For the input values corresponding to the 65536 16-bit values:
4318
* error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact
4320
* In all cases the inexact readings are only off by one.
4323
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
4324
/* The convert-to-sRGB table is only currently required for read. */
4325
const png_uint_16 png_sRGB_table[256] =
4327
0,20,40,60,80,99,119,139,
4328
159,179,199,219,241,264,288,313,
4329
340,367,396,427,458,491,526,562,
4330
599,637,677,718,761,805,851,898,
4331
947,997,1048,1101,1156,1212,1270,1330,
4332
1391,1453,1517,1583,1651,1720,1790,1863,
4333
1937,2013,2090,2170,2250,2333,2418,2504,
4334
2592,2681,2773,2866,2961,3058,3157,3258,
4335
3360,3464,3570,3678,3788,3900,4014,4129,
4336
4247,4366,4488,4611,4736,4864,4993,5124,
4337
5257,5392,5530,5669,5810,5953,6099,6246,
4338
6395,6547,6700,6856,7014,7174,7335,7500,
4339
7666,7834,8004,8177,8352,8528,8708,8889,
4340
9072,9258,9445,9635,9828,10022,10219,10417,
4341
10619,10822,11028,11235,11446,11658,11873,12090,
4342
12309,12530,12754,12980,13209,13440,13673,13909,
4343
14146,14387,14629,14874,15122,15371,15623,15878,
4344
16135,16394,16656,16920,17187,17456,17727,18001,
4345
18277,18556,18837,19121,19407,19696,19987,20281,
4346
20577,20876,21177,21481,21787,22096,22407,22721,
4347
23038,23357,23678,24002,24329,24658,24990,25325,
4348
25662,26001,26344,26688,27036,27386,27739,28094,
4349
28452,28813,29176,29542,29911,30282,30656,31033,
4350
31412,31794,32179,32567,32957,33350,33745,34143,
4351
34544,34948,35355,35764,36176,36591,37008,37429,
4352
37852,38278,38706,39138,39572,40009,40449,40891,
4353
41337,41785,42236,42690,43147,43606,44069,44534,
4354
45002,45473,45947,46423,46903,47385,47871,48359,
4355
48850,49344,49841,50341,50844,51349,51858,52369,
4356
52884,53401,53921,54445,54971,55500,56032,56567,
4357
57105,57646,58190,58737,59287,59840,60396,60955,
4358
61517,62082,62650,63221,63795,64372,64952,65535
4360
#endif /* SIMPLIFIED_READ */
4362
/* The base/delta tables are required for both read and write (but currently
4363
* only the simplified versions.)
4365
const png_uint_16 png_sRGB_base[512] =
4367
128,1782,3383,4644,5675,6564,7357,8074,
4368
8732,9346,9921,10463,10977,11466,11935,12384,
4369
12816,13233,13634,14024,14402,14769,15125,15473,
4370
15812,16142,16466,16781,17090,17393,17690,17981,
4371
18266,18546,18822,19093,19359,19621,19879,20133,
4372
20383,20630,20873,21113,21349,21583,21813,22041,
4373
22265,22487,22707,22923,23138,23350,23559,23767,
4374
23972,24175,24376,24575,24772,24967,25160,25352,
4375
25542,25730,25916,26101,26284,26465,26645,26823,
4376
27000,27176,27350,27523,27695,27865,28034,28201,
4377
28368,28533,28697,28860,29021,29182,29341,29500,
4378
29657,29813,29969,30123,30276,30429,30580,30730,
4379
30880,31028,31176,31323,31469,31614,31758,31902,
4380
32045,32186,32327,32468,32607,32746,32884,33021,
4381
33158,33294,33429,33564,33697,33831,33963,34095,
4382
34226,34357,34486,34616,34744,34873,35000,35127,
4383
35253,35379,35504,35629,35753,35876,35999,36122,
4384
36244,36365,36486,36606,36726,36845,36964,37083,
4385
37201,37318,37435,37551,37668,37783,37898,38013,
4386
38127,38241,38354,38467,38580,38692,38803,38915,
4387
39026,39136,39246,39356,39465,39574,39682,39790,
4388
39898,40005,40112,40219,40325,40431,40537,40642,
4389
40747,40851,40955,41059,41163,41266,41369,41471,
4390
41573,41675,41777,41878,41979,42079,42179,42279,
4391
42379,42478,42577,42676,42775,42873,42971,43068,
4392
43165,43262,43359,43456,43552,43648,43743,43839,
4393
43934,44028,44123,44217,44311,44405,44499,44592,
4394
44685,44778,44870,44962,45054,45146,45238,45329,
4395
45420,45511,45601,45692,45782,45872,45961,46051,
4396
46140,46229,46318,46406,46494,46583,46670,46758,
4397
46846,46933,47020,47107,47193,47280,47366,47452,
4398
47538,47623,47709,47794,47879,47964,48048,48133,
4399
48217,48301,48385,48468,48552,48635,48718,48801,
4400
48884,48966,49048,49131,49213,49294,49376,49458,
4401
49539,49620,49701,49782,49862,49943,50023,50103,
4402
50183,50263,50342,50422,50501,50580,50659,50738,
4403
50816,50895,50973,51051,51129,51207,51285,51362,
4404
51439,51517,51594,51671,51747,51824,51900,51977,
4405
52053,52129,52205,52280,52356,52432,52507,52582,
4406
52657,52732,52807,52881,52956,53030,53104,53178,
4407
53252,53326,53400,53473,53546,53620,53693,53766,
4408
53839,53911,53984,54056,54129,54201,54273,54345,
4409
54417,54489,54560,54632,54703,54774,54845,54916,
4410
54987,55058,55129,55199,55269,55340,55410,55480,
4411
55550,55620,55689,55759,55828,55898,55967,56036,
4412
56105,56174,56243,56311,56380,56448,56517,56585,
4413
56653,56721,56789,56857,56924,56992,57059,57127,
4414
57194,57261,57328,57395,57462,57529,57595,57662,
4415
57728,57795,57861,57927,57993,58059,58125,58191,
4416
58256,58322,58387,58453,58518,58583,58648,58713,
4417
58778,58843,58908,58972,59037,59101,59165,59230,
4418
59294,59358,59422,59486,59549,59613,59677,59740,
4419
59804,59867,59930,59993,60056,60119,60182,60245,
4420
60308,60370,60433,60495,60558,60620,60682,60744,
4421
60806,60868,60930,60992,61054,61115,61177,61238,
4422
61300,61361,61422,61483,61544,61605,61666,61727,
4423
61788,61848,61909,61969,62030,62090,62150,62211,
4424
62271,62331,62391,62450,62510,62570,62630,62689,
4425
62749,62808,62867,62927,62986,63045,63104,63163,
4426
63222,63281,63340,63398,63457,63515,63574,63632,
4427
63691,63749,63807,63865,63923,63981,64039,64097,
4428
64155,64212,64270,64328,64385,64443,64500,64557,
4429
64614,64672,64729,64786,64843,64900,64956,65013,
4430
65070,65126,65183,65239,65296,65352,65409,65465
4433
const png_byte png_sRGB_delta[512] =
4435
207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54,
4436
52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,
4437
35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28,
4438
28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24,
4439
23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21,
4440
21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19,
4441
19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17,
4442
17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16,
4443
16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15,
4444
15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14,
4445
14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13,
4446
13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12,
4447
12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,
4448
12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11,
4449
11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
4450
11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
4451
11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
4452
10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
4453
10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
4454
10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
4455
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
4456
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
4457
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
4458
9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
4459
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
4460
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
4461
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
4462
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
4463
8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7,
4464
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
4465
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
4466
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
4468
#endif /* SIMPLIFIED READ/WRITE sRGB support */
4470
/* SIMPLIFIED READ/WRITE SUPPORT */
4471
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
4472
defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
4474
png_image_free_function(png_voidp argument)
4476
png_imagep image = png_voidcast(png_imagep, argument);
4477
png_controlp cp = image->opaque;
4480
/* Double check that we have a png_ptr - it should be impossible to get here
4483
if (cp->png_ptr == NULL)
4486
/* First free any data held in the control structure. */
4487
# ifdef PNG_STDIO_SUPPORTED
4488
if (cp->owned_file != 0)
4490
FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr);
4493
/* Ignore errors here. */
4496
cp->png_ptr->io_ptr = NULL;
4502
/* Copy the control structure so that the original, allocated, version can be
4503
* safely freed. Notice that a png_error here stops the remainder of the
4504
* cleanup, but this is probably fine because that would indicate bad memory
4509
png_free(c.png_ptr, cp);
4511
/* Then the structures, calling the correct API. */
4512
if (c.for_write != 0)
4514
# ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
4515
png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
4517
png_error(c.png_ptr, "simplified write not supported");
4522
# ifdef PNG_SIMPLIFIED_READ_SUPPORTED
4523
png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL);
4525
png_error(c.png_ptr, "simplified read not supported");
4534
png_image_free(png_imagep image)
4536
/* Safely call the real function, but only if doing so is safe at this point
4537
* (if not inside an error handling context). Otherwise assume
4538
* png_safe_execute will call this API after the return.
4540
if (image != NULL && image->opaque != NULL &&
4541
image->opaque->error_buf == NULL)
4543
png_image_free_function(image);
4544
image->opaque = NULL;
4549
png_image_error(png_imagep image, png_const_charp error_message)
4551
/* Utility to log an error. */
4552
png_safecat(image->message, (sizeof image->message), 0, error_message);
4553
image->warning_or_error |= PNG_IMAGE_ERROR;
4554
png_image_free(image);
4558
#endif /* SIMPLIFIED READ/WRITE */
4559
#endif /* READ || WRITE */