4 * Last changed in libpng 1.6.31 [July 27, 2017]
5 * Copyright (c) 2013-2017 John Cunningham Bowler
7 * This code is released under the libpng license.
8 * For conditions of distribution and use, see the disclaimer
11 * Test for the PNG 'simplified' APIs.
13 #define _ISOC90_SOURCE 1
14 #define MALLOC_CHECK_ 2/*glibc facility: turn on debugging*/
24 #if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
28 /* Define the following to use this test against your installed libpng, rather
29 * than the one being built here:
31 #ifdef PNG_FREESTANDING_TESTS
34 # include "../../png.h"
37 /* 1.6.1 added support for the configure test harness, which uses 77 to indicate
38 * a skipped test, in earlier versions we need to succeed on a skipped test, so:
40 #if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
46 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED /* Else nothing can be done */
47 #include "../tools/sRGB.h"
51 * These defines switch on alternate algorithms for format conversions to match
52 * the current libpng implementation; they are set to allow pngstest to pass
53 * even though libpng is producing answers that are not as correct as they
56 #define ALLOW_UNUSED_GPC 0
57 /* If true include unused static GPC functions and declare an external array
58 * of them to hide the fact that they are unused. This is for development
59 * use while testing the correct function to use to take into account libpng
60 * misbehavior, such as using a simple power law to correct sRGB to linear.
63 /* The following is to support direct compilation of this file as C++ */
65 # define voidcast(type, value) static_cast<type>(value)
66 # define aligncastconst(type, value) \
67 static_cast<type>(static_cast<const void*>(value))
69 # define voidcast(type, value) (value)
70 # define aligncastconst(type, value) ((const void*)(value))
71 #endif /* __cplusplus */
73 /* During parallel runs of pngstest each temporary file needs a unique name,
74 * this is used to permit uniqueness using a command line argument which can be
75 * up to 22 characters long.
77 static char tmpf[23] = "TMP";
79 /* Generate random bytes. This uses a boring repeatable algorithm and it
80 * is implemented here so that it gives the same set of numbers on every
81 * architecture. It's a linear congruential generator (Knuth or Sedgewick
82 * "Algorithms") but it comes from the 'feedback taps' table in Horowitz and
83 * Hill, "The Art of Electronics".
86 make_random_bytes(png_uint_32* seed, void* pv, size_t size)
88 png_uint_32 u0 = seed[0], u1 = seed[1];
89 png_bytep bytes = voidcast(png_bytep, pv);
91 /* There are thirty three bits, the next bit in the sequence is bit-33 XOR
92 * bit-20. The top 1 bit is in u1, the bottom 32 are in u0.
95 for (i=0; i<size; ++i)
97 /* First generate 8 new bits then shift them in at the end. */
98 png_uint_32 u = ((u0 >> (20-8)) ^ ((u1 << 7) | (u0 >> (32-7)))) & 0xff;
103 *bytes++ = (png_byte)u;
110 static png_uint_32 color_seed[2];
115 color_seed[0] = 0x12345678U;
116 color_seed[1] = 0x9abcdefU;
120 random_color(png_colorp color)
122 make_random_bytes(color_seed, color, sizeof *color);
125 /* Math support - neither Cygwin nor Visual Studio have C99 support and we need
126 * a predictable rounding function, so make one here:
129 closestinteger(double x)
131 return floor(x + .5);
134 /* Cast support: remove GCC whines. */
138 d = closestinteger(d);
145 d = closestinteger(d);
146 return (png_uint_16)d;
149 /* sRGB support: use exact calculations rounded to the nearest int, see the
150 * fesetround() call in main(). sRGB_to_d optimizes the 8 to 16-bit conversion.
152 static double sRGB_to_d[256];
153 static double g22_to_d[256];
161 for (i=1; i<255; ++i)
162 sRGB_to_d[i] = linear_from_sRGB(i/255.);
166 for (i=1; i<255; ++i)
167 g22_to_d[i] = pow(i/255., 1/.45455);
172 sRGB(double linear /*range 0.0 .. 1.0*/)
174 return u8d(255 * sRGB_from_linear(linear));
178 isRGB(int fixed_linear)
180 return sRGB(fixed_linear / 65535.);
185 unpremultiply(int component, int alpha)
187 if (alpha <= component)
188 return 255; /* Arbitrary, but consistent with the libpng code */
190 else if (alpha >= 65535)
191 return isRGB(component);
194 return sRGB((double)component / alpha);
199 ilinear(int fixed_srgb)
201 return u16d(65535 * sRGB_to_d[fixed_srgb]);
205 ilineara(int fixed_srgb, int alpha)
207 return u16d((257 * alpha) * sRGB_to_d[fixed_srgb]);
211 ilinear_g22(int fixed_srgb)
213 return u16d(65535 * g22_to_d[fixed_srgb]);
218 ilineara_g22(int fixed_srgb, int alpha)
220 return u16d((257 * alpha) * g22_to_d[fixed_srgb]);
225 YfromRGBint(int ir, int ig, int ib)
230 return YfromRGB(r, g, b);
234 /* The error that results from using a 2.2 power law in place of the correct
235 * sRGB transform, given an 8-bit value which might be either sRGB or power-law.
238 power_law_error8(int value)
240 if (value > 0 && value < 255)
242 double vd = value / 255.;
244 pow(sRGB_to_d[value], 1/2.2) - sRGB_from_linear(pow(vd, 2.2)));
246 /* Always allow an extra 1 here for rounding errors */
247 e = 1+floor(255 * e);
254 static int error_in_sRGB_roundtrip = 56; /* by experiment */
256 power_law_error16(int value)
258 if (value > 0 && value < 65535)
260 /* Round trip the value through an 8-bit representation but using
261 * non-matching to/from conversions.
263 double vd = value / 65535.;
265 pow(sRGB_from_linear(vd), 2.2) - linear_from_sRGB(pow(vd, 1/2.2)));
267 /* Always allow an extra 1 here for rounding errors */
268 e = error_in_sRGB_roundtrip+floor(65535 * e);
276 compare_8bit(int v1, int v2, int error_limit, int multiple_algorithms)
281 if (e <= error_limit)
284 if (!multiple_algorithms)
287 ev1 = power_law_error8(v1);
291 ev2 = power_law_error8(v2);
299 compare_16bit(int v1, int v2, int error_limit, int multiple_algorithms)
304 if (e <= error_limit)
307 /* "multiple_algorithms" in this case means that a color-map has been
308 * involved somewhere, so we can deduce that the values were forced to 8-bit
309 * (like the via_linear case for 8-bit.)
311 if (!multiple_algorithms)
314 ev1 = power_law_error16(v1);
318 ev2 = power_law_error16(v2);
326 #define USE_FILE 1 /* else memory */
327 #define USE_STDIO 2 /* else use file name */
328 #define STRICT 4 /* fail on warnings too */
330 #define KEEP_TMPFILES 16 /* else delete temporary files */
331 #define KEEP_GOING 32
332 #define ACCUMULATE 64
333 #define FAST_WRITE 128
334 #define sRGB_16BIT 256
335 #define NO_RESEED 512 /* do not reseed on each new file */
336 #define GBG_ERROR 1024 /* do not ignore the gamma+background_rgb_to_gray
340 print_opts(png_uint_32 opts)
344 if (opts & USE_STDIO)
346 if (!(opts & STRICT))
347 printf(" --nostrict");
349 printf(" --verbose");
350 if (opts & KEEP_TMPFILES)
351 printf(" --preserve");
352 if (opts & KEEP_GOING)
353 printf(" --keep-going");
354 if (opts & ACCUMULATE)
355 printf(" --accumulate");
356 if (!(opts & FAST_WRITE)) /* --fast is currently the default */
358 if (opts & sRGB_16BIT)
359 printf(" --sRGB-16bit");
360 if (opts & NO_RESEED)
361 printf(" --noreseed");
362 #if PNG_LIBPNG_VER < 10700 /* else on by default */
363 if (opts & GBG_ERROR)
364 printf(" --fault-gbg-warning");
368 #define FORMAT_NO_CHANGE 0x80000000 /* additional flag */
370 /* A name table for all the formats - defines the format of the '+' arguments to
373 #define FORMAT_COUNT 64
374 #define FORMAT_MASK 0x3f
375 static const char * const format_names[FORMAT_COUNT] =
386 "color-mapped-sRGB-gray",
387 "color-mapped-sRGB-gray+alpha",
388 "color-mapped-sRGB-rgb",
389 "color-mapped-sRGB-rgb+alpha",
390 "color-mapped-linear-gray",
391 "color-mapped-linear-gray+alpha",
392 "color-mapped-linear-rgb",
393 "color-mapped-linear-rgb+alpha",
404 "color-mapped-sRGB-gray",
405 "color-mapped-sRGB-gray+alpha",
406 "color-mapped-sRGB-bgr",
407 "color-mapped-sRGB-bgr+alpha",
408 "color-mapped-linear-gray",
409 "color-mapped-linear-gray+alpha",
410 "color-mapped-linear-bgr",
411 "color-mapped-linear-bgr+alpha",
422 "color-mapped-sRGB-gray",
423 "color-mapped-alpha+sRGB-gray",
424 "color-mapped-sRGB-rgb",
425 "color-mapped-alpha+sRGB-rgb",
426 "color-mapped-linear-gray",
427 "color-mapped-alpha+linear-gray",
428 "color-mapped-linear-rgb",
429 "color-mapped-alpha+linear-rgb",
440 "color-mapped-sRGB-gray",
441 "color-mapped-alpha+sRGB-gray",
442 "color-mapped-sRGB-bgr",
443 "color-mapped-alpha+sRGB-bgr",
444 "color-mapped-linear-gray",
445 "color-mapped-alpha+linear-gray",
446 "color-mapped-linear-bgr",
447 "color-mapped-alpha+linear-bgr",
450 /* Decode an argument to a format number. */
452 formatof(const char *arg)
455 unsigned long format = strtoul(arg, &ep, 0);
457 if (ep > arg && *ep == 0 && format < FORMAT_COUNT)
458 return (png_uint_32)format;
460 else for (format=0; format < FORMAT_COUNT; ++format)
462 if (strcmp(format_names[format], arg) == 0)
463 return (png_uint_32)format;
466 fprintf(stderr, "pngstest: format name '%s' invalid\n", arg);
470 /* Bitset/test functions for formats */
471 #define FORMAT_SET_COUNT (FORMAT_COUNT / 32)
474 png_uint_32 bits[FORMAT_SET_COUNT];
478 static void format_init(format_list *pf)
481 for (i=0; i<FORMAT_SET_COUNT; ++i)
482 pf->bits[i] = 0; /* All off */
485 #if 0 /* currently unused */
486 static void format_clear(format_list *pf)
489 for (i=0; i<FORMAT_SET_COUNT; ++i)
494 static int format_is_initial(format_list *pf)
497 for (i=0; i<FORMAT_SET_COUNT; ++i)
498 if (pf->bits[i] != 0)
504 static int format_set(format_list *pf, png_uint_32 format)
506 if (format < FORMAT_COUNT)
507 return pf->bits[format >> 5] |= ((png_uint_32)1) << (format & 31);
512 #if 0 /* currently unused */
513 static int format_unset(format_list *pf, png_uint_32 format)
515 if (format < FORMAT_COUNT)
516 return pf->bits[format >> 5] &= ~((png_uint_32)1) << (format & 31);
522 static int format_isset(format_list *pf, png_uint_32 format)
524 return format < FORMAT_COUNT &&
525 (pf->bits[format >> 5] & (((png_uint_32)1) << (format & 31))) != 0;
528 static void format_default(format_list *pf, int redundant)
534 /* set everything, including flags that are pointless */
535 for (i=0; i<FORMAT_SET_COUNT; ++i)
536 pf->bits[i] = ~(png_uint_32)0;
543 for (f=0; f<FORMAT_COUNT; ++f)
545 /* Eliminate redundant and unsupported settings. */
546 # ifdef PNG_FORMAT_BGR_SUPPORTED
547 /* BGR is meaningless if no color: */
548 if ((f & PNG_FORMAT_FLAG_COLOR) == 0 &&
549 (f & PNG_FORMAT_FLAG_BGR) != 0)
551 if ((f & 0x10U/*HACK: fixed value*/) != 0)
555 /* AFIRST is meaningless if no alpha: */
556 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
557 if ((f & PNG_FORMAT_FLAG_ALPHA) == 0 &&
558 (f & PNG_FORMAT_FLAG_AFIRST) != 0)
560 if ((f & 0x20U/*HACK: fixed value*/) != 0)
569 /* THE Image STRUCTURE */
570 /* The super-class of a png_image, contains the decoded image plus the input
571 * data necessary to re-read the file with a different format.
577 const char *file_name;
580 png_voidp input_memory;
581 size_t input_memory_size;
586 char tmpfile_name[32];
587 png_uint_16 colormap[256*4];
591 /* Initializer: also sets the permitted error limit for 16-bit operations. */
593 newimage(Image *image)
595 memset(image, 0, sizeof *image);
598 /* Reset the image to be read again - only needs to rewind the FILE* at present.
601 resetimage(Image *image)
603 if (image->input_file != NULL)
604 rewind(image->input_file);
607 /* Free the image buffer; the buffer is re-used on a re-read, this is just for
611 freebuffer(Image *image)
613 if (image->buffer) free(image->buffer);
614 image->buffer = NULL;
616 image->allocsize = 0;
619 /* Delete function; cleans out all the allocated data and the temporary file in
623 freeimage(Image *image)
626 png_image_free(&image->image);
628 if (image->input_file != NULL)
630 fclose(image->input_file);
631 image->input_file = NULL;
634 if (image->input_memory != NULL)
636 free(image->input_memory);
637 image->input_memory = NULL;
638 image->input_memory_size = 0;
641 if (image->tmpfile_name[0] != 0 && (image->opts & KEEP_TMPFILES) == 0)
643 (void)remove(image->tmpfile_name);
644 image->tmpfile_name[0] = 0;
648 /* This is actually a re-initializer; allows an image structure to be re-used by
649 * freeing everything that relates to an old image.
651 static void initimage(Image *image, png_uint_32 opts, const char *file_name,
655 memset(&image->image, 0, sizeof image->image);
657 image->file_name = file_name;
658 image->stride_extra = stride_extra;
661 /* Make sure the image buffer is big enough; allows re-use of the buffer if the
664 #define BUFFER_INIT8 73
666 allocbuffer(Image *image)
668 size_t size = PNG_IMAGE_BUFFER_SIZE(image->image, image->stride);
670 if (size+32 > image->bufsize)
673 image->buffer = voidcast(png_bytep, malloc(size+32));
674 if (image->buffer == NULL)
678 "simpletest: out of memory allocating %lu(+32) byte buffer\n",
679 (unsigned long)size);
682 image->bufsize = size+32;
685 memset(image->buffer, 95, image->bufsize);
686 memset(image->buffer+16, BUFFER_INIT8, size);
687 image->allocsize = size;
690 /* Make sure 16 bytes match the given byte. */
692 check16(png_const_bytep bp, int b)
697 if (*bp != b) return 1;
703 /* Check for overwrite in the image buffer. */
705 checkbuffer(Image *image, const char *arg)
707 if (check16(image->buffer, 95))
710 fprintf(stderr, "%s: overwrite at start of image buffer\n", arg);
714 if (check16(image->buffer+16+image->allocsize, 95))
717 fprintf(stderr, "%s: overwrite at end of image buffer\n", arg);
723 /* Log a terminal error, also frees the libpng part of the image if necessary.
726 logerror(Image *image, const char *a1, const char *a2, const char *a3)
729 if (image->image.warning_or_error)
730 fprintf(stderr, "%s%s%s: %s\n", a1, a2, a3, image->image.message);
733 fprintf(stderr, "%s%s%s\n", a1, a2, a3);
735 if (image->image.opaque != NULL)
737 fprintf(stderr, "%s: image opaque pointer non-NULL on error\n",
739 png_image_free(&image->image);
745 /* Log an error and close a file (just a utility to do both things in one
749 logclose(Image *image, FILE *f, const char *name, const char *operation)
754 return logerror(image, name, operation, strerror(e));
757 /* Make sure the png_image has been freed - validates that libpng is doing what
758 * the spec says and freeing the image.
761 checkopaque(Image *image)
763 if (image->image.opaque != NULL)
765 png_image_free(&image->image);
766 return logerror(image, image->file_name, ": opaque not NULL", "");
769 /* Separate out the gamma+background_rgb_to_gray warning because it may
770 * produce opaque component errors:
772 else if (image->image.warning_or_error != 0 &&
773 (strcmp(image->image.message,
774 "libpng does not support gamma+background+rgb_to_gray") == 0 ?
775 (image->opts & GBG_ERROR) != 0 : (image->opts & STRICT) != 0))
776 return logerror(image, image->file_name, (image->opts & GBG_ERROR) != 0 ?
777 " --fault-gbg-warning" : " --strict", "");
783 /* IMAGE COMPARISON/CHECKING */
784 /* Compare the pixels of two images, which should be the same but aren't. The
785 * images must have been checked for a size match.
789 /* The components, for grayscale images the gray value is in 'g' and if alpha
790 * is not present 'a' is set to 255 or 65535 according to format.
797 /* The background as the original sRGB 8-bit value converted to the final
798 * integer format and as a double precision linear value in the range 0..1
799 * for with partially transparent pixels.
802 double dr, dg, db; /* linear r,g,b scaled to 0..1 */
805 /* Basic image formats; control the data but not the layout thereof. */
806 #define BASE_FORMATS\
807 (PNG_FORMAT_FLAG_ALPHA|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_LINEAR)
809 /* Read a Pixel from a buffer. The code below stores the correct routine for
810 * the format in a function pointer, these are the routines:
813 gp_g8(Pixel *p, png_const_voidp pb)
815 png_const_bytep pp = voidcast(png_const_bytep, pb);
817 p->r = p->g = p->b = pp[0];
822 gp_ga8(Pixel *p, png_const_voidp pb)
824 png_const_bytep pp = voidcast(png_const_bytep, pb);
826 p->r = p->g = p->b = pp[0];
830 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
832 gp_ag8(Pixel *p, png_const_voidp pb)
834 png_const_bytep pp = voidcast(png_const_bytep, pb);
836 p->r = p->g = p->b = pp[1];
842 gp_rgb8(Pixel *p, png_const_voidp pb)
844 png_const_bytep pp = voidcast(png_const_bytep, pb);
852 #ifdef PNG_FORMAT_BGR_SUPPORTED
854 gp_bgr8(Pixel *p, png_const_voidp pb)
856 png_const_bytep pp = voidcast(png_const_bytep, pb);
866 gp_rgba8(Pixel *p, png_const_voidp pb)
868 png_const_bytep pp = voidcast(png_const_bytep, pb);
876 #ifdef PNG_FORMAT_BGR_SUPPORTED
878 gp_bgra8(Pixel *p, png_const_voidp pb)
880 png_const_bytep pp = voidcast(png_const_bytep, pb);
889 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
891 gp_argb8(Pixel *p, png_const_voidp pb)
893 png_const_bytep pp = voidcast(png_const_bytep, pb);
902 #if defined(PNG_FORMAT_AFIRST_SUPPORTED) && defined(PNG_FORMAT_BGR_SUPPORTED)
904 gp_abgr8(Pixel *p, png_const_voidp pb)
906 png_const_bytep pp = voidcast(png_const_bytep, pb);
916 gp_g16(Pixel *p, png_const_voidp pb)
918 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
920 p->r = p->g = p->b = pp[0];
925 gp_ga16(Pixel *p, png_const_voidp pb)
927 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
929 p->r = p->g = p->b = pp[0];
933 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
935 gp_ag16(Pixel *p, png_const_voidp pb)
937 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
939 p->r = p->g = p->b = pp[1];
945 gp_rgb16(Pixel *p, png_const_voidp pb)
947 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
955 #ifdef PNG_FORMAT_BGR_SUPPORTED
957 gp_bgr16(Pixel *p, png_const_voidp pb)
959 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
969 gp_rgba16(Pixel *p, png_const_voidp pb)
971 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
979 #ifdef PNG_FORMAT_BGR_SUPPORTED
981 gp_bgra16(Pixel *p, png_const_voidp pb)
983 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
992 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
994 gp_argb16(Pixel *p, png_const_voidp pb)
996 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
1005 #if defined(PNG_FORMAT_AFIRST_SUPPORTED) && defined(PNG_FORMAT_BGR_SUPPORTED)
1007 gp_abgr16(Pixel *p, png_const_voidp pb)
1009 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
1018 /* Given a format, return the correct one of the above functions. */
1020 get_pixel(png_uint_32 format))(Pixel *p, png_const_voidp pb)
1022 /* The color-map flag is irrelevant here - the caller of the function
1023 * returned must either pass the buffer or, for a color-mapped image, the
1024 * correct entry in the color-map.
1026 if (format & PNG_FORMAT_FLAG_LINEAR)
1028 if (format & PNG_FORMAT_FLAG_COLOR)
1030 # ifdef PNG_FORMAT_BGR_SUPPORTED
1031 if (format & PNG_FORMAT_FLAG_BGR)
1033 if (format & PNG_FORMAT_FLAG_ALPHA)
1035 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1036 if (format & PNG_FORMAT_FLAG_AFIRST)
1051 if (format & PNG_FORMAT_FLAG_ALPHA)
1053 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1054 if (format & PNG_FORMAT_FLAG_AFIRST)
1069 if (format & PNG_FORMAT_FLAG_ALPHA)
1071 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1072 if (format & PNG_FORMAT_FLAG_AFIRST)
1087 if (format & PNG_FORMAT_FLAG_COLOR)
1089 # ifdef PNG_FORMAT_BGR_SUPPORTED
1090 if (format & PNG_FORMAT_FLAG_BGR)
1092 if (format & PNG_FORMAT_FLAG_ALPHA)
1094 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1095 if (format & PNG_FORMAT_FLAG_AFIRST)
1110 if (format & PNG_FORMAT_FLAG_ALPHA)
1112 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1113 if (format & PNG_FORMAT_FLAG_AFIRST)
1128 if (format & PNG_FORMAT_FLAG_ALPHA)
1130 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1131 if (format & PNG_FORMAT_FLAG_AFIRST)
1145 /* Conversion between pixel formats. The code above effectively eliminates the
1146 * component ordering changes leaving three basic changes:
1148 * 1) Remove an alpha channel by pre-multiplication or compositing on a
1149 * background color. (Adding an alpha channel is a no-op.)
1151 * 2) Remove color by mapping to grayscale. (Grayscale to color is a no-op.)
1153 * 3) Convert between 8-bit and 16-bit components. (Both directtions are
1156 * This gives the following base format conversion matrix:
1158 * OUT: ----- 8-bit ----- ----- 16-bit -----
1159 * IN G GA RGB RGBA G GA RGB RGBA
1160 * 8 G . . . . lin lin lin lin
1161 * 8 GA bckg . bckc . pre' pre pre' pre
1162 * 8 RGB g8 g8 . . glin glin lin lin
1163 * 8 RGBA g8b g8 bckc . gpr' gpre pre' pre
1164 * 16 G sRGB sRGB sRGB sRGB . . . .
1165 * 16 GA b16g unpg b16c unpc A . A .
1166 * 16 RGB sG sG sRGB sRGB g16 g16 . .
1167 * 16 RGBA gb16 sGp cb16 sCp g16 g16' A .
1170 * bckg: composite on gray background
1171 * bckc: composite on color background
1172 * g8: convert sRGB components to sRGB grayscale
1173 * g8b: convert sRGB components to grayscale and composite on gray background
1176 * lin: make sRGB components linear, alpha := 65535
1177 * pre: make sRGB components linear and premultiply by alpha (scale alpha)
1178 * pre': as 'pre' but alpha := 65535
1179 * glin: make sRGB components linear, convert to grayscale, alpha := 65535
1180 * gpre: make sRGB components grayscale and linear and premultiply by alpha
1181 * gpr': as 'gpre' but alpha := 65535
1184 * sRGB: convert linear components to sRGB, alpha := 255
1185 * unpg: unpremultiply gray component and convert to sRGB (scale alpha)
1186 * unpc: unpremultiply color components and convert to sRGB (scale alpha)
1187 * b16g: composite linear onto gray background and convert the result to sRGB
1188 * b16c: composite linear onto color background and convert the result to sRGB
1189 * sG: convert linear RGB to sRGB grayscale
1190 * sGp: unpremultiply RGB then convert to sRGB grayscale
1191 * sCp: unpremultiply RGB then convert to sRGB
1192 * gb16: composite linear onto background and convert to sRGB grayscale
1193 * (order doesn't matter, the composite and grayscale operations permute)
1194 * cb16: composite linear onto background and convert to sRGB
1197 * A: set alpha to 65535
1198 * g16: convert linear RGB to linear grayscale (alpha := 65535)
1199 * g16': as 'g16' but alpha is unchanged
1203 gpc_noop(Pixel *out, const Pixel *in, const Background *back)
1212 #if ALLOW_UNUSED_GPC
1214 gpc_nop8(Pixel *out, const Pixel *in, const Background *back)
1218 out->r = out->g = out->b = 255;
1231 #if ALLOW_UNUSED_GPC
1233 gpc_nop6(Pixel *out, const Pixel *in, const Background *back)
1237 out->r = out->g = out->b = 65535;
1250 /* 8-bit to 8-bit conversions */
1251 /* bckg: composite on gray background */
1253 gpc_bckg(Pixel *out, const Pixel *in, const Background *back)
1256 out->r = out->g = out->b = back->ig;
1258 else if (in->a >= 255)
1259 out->r = out->g = out->b = in->g;
1263 double a = in->a / 255.;
1265 out->r = out->g = out->b = sRGB(sRGB_to_d[in->g] * a + back->dg * (1-a));
1271 /* bckc: composite on color background */
1273 gpc_bckc(Pixel *out, const Pixel *in, const Background *back)
1282 else if (in->a >= 255)
1291 double a = in->a / 255.;
1293 out->r = sRGB(sRGB_to_d[in->r] * a + back->dr * (1-a));
1294 out->g = sRGB(sRGB_to_d[in->g] * a + back->dg * (1-a));
1295 out->b = sRGB(sRGB_to_d[in->b] * a + back->db * (1-a));
1301 /* g8: convert sRGB components to sRGB grayscale */
1303 gpc_g8(Pixel *out, const Pixel *in, const Background *back)
1307 if (in->r == in->g && in->g == in->b)
1308 out->r = out->g = out->b = in->g;
1311 out->r = out->g = out->b =
1312 sRGB(YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
1317 /* g8b: convert sRGB components to grayscale and composite on gray background */
1319 gpc_g8b(Pixel *out, const Pixel *in, const Background *back)
1322 out->r = out->g = out->b = back->ig;
1324 else if (in->a >= 255)
1326 if (in->r == in->g && in->g == in->b)
1327 out->r = out->g = out->b = in->g;
1330 out->r = out->g = out->b = sRGB(YfromRGB(
1331 sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
1336 double a = in->a/255.;
1338 out->r = out->g = out->b = sRGB(a * YfromRGB(sRGB_to_d[in->r],
1339 sRGB_to_d[in->g], sRGB_to_d[in->b]) + back->dg * (1-a));
1345 /* 8-bit to 16-bit conversions */
1346 /* lin: make sRGB components linear, alpha := 65535 */
1348 gpc_lin(Pixel *out, const Pixel *in, const Background *back)
1352 out->r = ilinear(in->r);
1362 out->b = ilinear(in->b);
1367 out->g = ilinear(in->g);
1372 else if (in->b == in->g)
1376 out->b = ilinear(in->b);
1382 /* pre: make sRGB components linear and premultiply by alpha (scale alpha) */
1384 gpc_pre(Pixel *out, const Pixel *in, const Background *back)
1388 out->r = ilineara(in->r, in->a);
1398 out->b = ilineara(in->b, in->a);
1403 out->g = ilineara(in->g, in->a);
1408 else if (in->b == in->g)
1412 out->b = ilineara(in->b, in->a);
1415 out->a = in->a * 257;
1418 /* pre': as 'pre' but alpha := 65535 */
1420 gpc_preq(Pixel *out, const Pixel *in, const Background *back)
1424 out->r = ilineara(in->r, in->a);
1434 out->b = ilineara(in->b, in->a);
1439 out->g = ilineara(in->g, in->a);
1444 else if (in->b == in->g)
1448 out->b = ilineara(in->b, in->a);
1454 /* glin: make sRGB components linear, convert to grayscale, alpha := 65535 */
1456 gpc_glin(Pixel *out, const Pixel *in, const Background *back)
1460 if (in->r == in->g && in->g == in->b)
1461 out->r = out->g = out->b = ilinear(in->g);
1464 out->r = out->g = out->b = u16d(65535 *
1465 YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
1470 /* gpre: make sRGB components grayscale and linear and premultiply by alpha */
1472 gpc_gpre(Pixel *out, const Pixel *in, const Background *back)
1476 if (in->r == in->g && in->g == in->b)
1477 out->r = out->g = out->b = ilineara(in->g, in->a);
1480 out->r = out->g = out->b = u16d(in->a * 257 *
1481 YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
1483 out->a = 257 * in->a;
1486 /* gpr': as 'gpre' but alpha := 65535 */
1488 gpc_gprq(Pixel *out, const Pixel *in, const Background *back)
1492 if (in->r == in->g && in->g == in->b)
1493 out->r = out->g = out->b = ilineara(in->g, in->a);
1496 out->r = out->g = out->b = u16d(in->a * 257 *
1497 YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
1502 /* 8-bit to 16-bit conversions for gAMA 45455 encoded values */
1503 /* Lin: make gAMA 45455 components linear, alpha := 65535 */
1505 gpc_Lin(Pixel *out, const Pixel *in, const Background *back)
1509 out->r = ilinear_g22(in->r);
1519 out->b = ilinear_g22(in->b);
1524 out->g = ilinear_g22(in->g);
1529 else if (in->b == in->g)
1533 out->b = ilinear_g22(in->b);
1539 #if ALLOW_UNUSED_GPC
1540 /* Pre: make gAMA 45455 components linear and premultiply by alpha (scale alpha)
1543 gpc_Pre(Pixel *out, const Pixel *in, const Background *back)
1547 out->r = ilineara_g22(in->r, in->a);
1557 out->b = ilineara_g22(in->b, in->a);
1562 out->g = ilineara_g22(in->g, in->a);
1567 else if (in->b == in->g)
1571 out->b = ilineara_g22(in->b, in->a);
1574 out->a = in->a * 257;
1578 #if ALLOW_UNUSED_GPC
1579 /* Pre': as 'Pre' but alpha := 65535 */
1581 gpc_Preq(Pixel *out, const Pixel *in, const Background *back)
1585 out->r = ilineara_g22(in->r, in->a);
1595 out->b = ilineara_g22(in->b, in->a);
1600 out->g = ilineara_g22(in->g, in->a);
1605 else if (in->b == in->g)
1609 out->b = ilineara_g22(in->b, in->a);
1616 #if ALLOW_UNUSED_GPC
1617 /* Glin: make gAMA 45455 components linear, convert to grayscale, alpha := 65535
1620 gpc_Glin(Pixel *out, const Pixel *in, const Background *back)
1624 if (in->r == in->g && in->g == in->b)
1625 out->r = out->g = out->b = ilinear_g22(in->g);
1628 out->r = out->g = out->b = u16d(65535 *
1629 YfromRGB(g22_to_d[in->r], g22_to_d[in->g], g22_to_d[in->b]));
1635 #if ALLOW_UNUSED_GPC
1636 /* Gpre: make gAMA 45455 components grayscale and linear and premultiply by
1640 gpc_Gpre(Pixel *out, const Pixel *in, const Background *back)
1644 if (in->r == in->g && in->g == in->b)
1645 out->r = out->g = out->b = ilineara_g22(in->g, in->a);
1648 out->r = out->g = out->b = u16d(in->a * 257 *
1649 YfromRGB(g22_to_d[in->r], g22_to_d[in->g], g22_to_d[in->b]));
1651 out->a = 257 * in->a;
1655 #if ALLOW_UNUSED_GPC
1656 /* Gpr': as 'Gpre' but alpha := 65535 */
1658 gpc_Gprq(Pixel *out, const Pixel *in, const Background *back)
1662 if (in->r == in->g && in->g == in->b)
1663 out->r = out->g = out->b = ilineara_g22(in->g, in->a);
1666 out->r = out->g = out->b = u16d(in->a * 257 *
1667 YfromRGB(g22_to_d[in->r], g22_to_d[in->g], g22_to_d[in->b]));
1673 /* 16-bit to 8-bit conversions */
1674 /* sRGB: convert linear components to sRGB, alpha := 255 */
1676 gpc_sRGB(Pixel *out, const Pixel *in, const Background *back)
1680 out->r = isRGB(in->r);
1690 out->b = isRGB(in->b);
1695 out->g = isRGB(in->g);
1700 else if (in->b == in->g)
1704 out->b = isRGB(in->b);
1710 /* unpg: unpremultiply gray component and convert to sRGB (scale alpha) */
1712 gpc_unpg(Pixel *out, const Pixel *in, const Background *back)
1718 out->r = out->g = out->b = 255;
1724 out->r = out->g = out->b = sRGB((double)in->g / in->a);
1725 out->a = u8d(in->a / 257.);
1729 /* unpc: unpremultiply color components and convert to sRGB (scale alpha) */
1731 gpc_unpc(Pixel *out, const Pixel *in, const Background *back)
1737 out->r = out->g = out->b = 255;
1743 out->r = sRGB((double)in->r / in->a);
1744 out->g = sRGB((double)in->g / in->a);
1745 out->b = sRGB((double)in->b / in->a);
1746 out->a = u8d(in->a / 257.);
1750 /* b16g: composite linear onto gray background and convert the result to sRGB */
1752 gpc_b16g(Pixel *out, const Pixel *in, const Background *back)
1755 out->r = out->g = out->b = back->ig;
1759 double a = in->a/65535.;
1763 out->r = out->g = out->b = sRGB(in->g * a + back->dg * a1);
1769 /* b16c: composite linear onto color background and convert the result to sRGB*/
1771 gpc_b16c(Pixel *out, const Pixel *in, const Background *back)
1782 double a = in->a/65535.;
1786 out->r = sRGB(in->r * a + back->dr * a1);
1787 out->g = sRGB(in->g * a + back->dg * a1);
1788 out->b = sRGB(in->b * a + back->db * a1);
1794 /* sG: convert linear RGB to sRGB grayscale */
1796 gpc_sG(Pixel *out, const Pixel *in, const Background *back)
1800 out->r = out->g = out->b = sRGB(YfromRGBint(in->r, in->g, in->b)/65535);
1804 /* sGp: unpremultiply RGB then convert to sRGB grayscale */
1806 gpc_sGp(Pixel *out, const Pixel *in, const Background *back)
1812 out->r = out->g = out->b = 255;
1818 out->r = out->g = out->b = sRGB(YfromRGBint(in->r, in->g, in->b)/in->a);
1819 out->a = u8d(in->a / 257.);
1823 /* sCp: unpremultiply RGB then convert to sRGB */
1825 gpc_sCp(Pixel *out, const Pixel *in, const Background *back)
1831 out->r = out->g = out->b = 255;
1837 out->r = sRGB((double)in->r / in->a);
1838 out->g = sRGB((double)in->g / in->a);
1839 out->b = sRGB((double)in->b / in->a);
1840 out->a = u8d(in->a / 257.);
1844 /* gb16: composite linear onto background and convert to sRGB grayscale */
1845 /* (order doesn't matter, the composite and grayscale operations permute) */
1847 gpc_gb16(Pixel *out, const Pixel *in, const Background *back)
1850 out->r = out->g = out->b = back->ig;
1852 else if (in->a >= 65535)
1853 out->r = out->g = out->b = isRGB(in->g);
1857 double a = in->a / 65535.;
1861 out->r = out->g = out->b = sRGB(in->g * a + back->dg * a1);
1867 /* cb16: composite linear onto background and convert to sRGB */
1869 gpc_cb16(Pixel *out, const Pixel *in, const Background *back)
1878 else if (in->a >= 65535)
1880 out->r = isRGB(in->r);
1881 out->g = isRGB(in->g);
1882 out->b = isRGB(in->b);
1887 double a = in->a / 65535.;
1891 out->r = sRGB(in->r * a + back->dr * a1);
1892 out->g = sRGB(in->g * a + back->dg * a1);
1893 out->b = sRGB(in->b * a + back->db * a1);
1899 /* 16-bit to 16-bit conversions */
1900 /* A: set alpha to 65535 */
1902 gpc_A(Pixel *out, const Pixel *in, const Background *back)
1911 /* g16: convert linear RGB to linear grayscale (alpha := 65535) */
1913 gpc_g16(Pixel *out, const Pixel *in, const Background *back)
1916 out->r = out->g = out->b = u16d(YfromRGBint(in->r, in->g, in->b));
1920 /* g16': as 'g16' but alpha is unchanged */
1922 gpc_g16q(Pixel *out, const Pixel *in, const Background *back)
1925 out->r = out->g = out->b = u16d(YfromRGBint(in->r, in->g, in->b));
1929 #if ALLOW_UNUSED_GPC
1930 /* Unused functions (to hide them from GCC unused function warnings) */
1931 void (* const gpc_unused[])
1932 (Pixel *out, const Pixel *in, const Background *back) =
1934 gpc_Pre, gpc_Preq, gpc_Glin, gpc_Gpre, gpc_Gprq, gpc_nop8, gpc_nop6
1938 /* OUT: ----- 8-bit ----- ----- 16-bit -----
1939 * IN G GA RGB RGBA G GA RGB RGBA
1940 * 8 G . . . . lin lin lin lin
1941 * 8 GA bckg . bckc . pre' pre pre' pre
1942 * 8 RGB g8 g8 . . glin glin lin lin
1943 * 8 RGBA g8b g8 bckc . gpr' gpre pre' pre
1944 * 16 G sRGB sRGB sRGB sRGB . . . .
1945 * 16 GA b16g unpg b16c unpc A . A .
1946 * 16 RGB sG sG sRGB sRGB g16 g16 . .
1947 * 16 RGBA gb16 sGp cb16 sCp g16 g16' A .
1949 * The matrix is held in an array indexed thus:
1951 * gpc_fn[out_format & BASE_FORMATS][in_format & BASE_FORMATS];
1953 /* This will produce a compile time error if the FORMAT_FLAG values don't
1954 * match the above matrix!
1956 #if PNG_FORMAT_FLAG_ALPHA == 1 && PNG_FORMAT_FLAG_COLOR == 2 &&\
1957 PNG_FORMAT_FLAG_LINEAR == 4
1958 static void (* const gpc_fn[8/*in*/][8/*out*/])
1959 (Pixel *out, const Pixel *in, const Background *back) =
1961 /*out: G-8 GA-8 RGB-8 RGBA-8 G-16 GA-16 RGB-16 RGBA-16 */
1962 {gpc_noop,gpc_noop,gpc_noop,gpc_noop, gpc_Lin, gpc_Lin, gpc_Lin, gpc_Lin },
1963 {gpc_bckg,gpc_noop,gpc_bckc,gpc_noop, gpc_preq,gpc_pre, gpc_preq,gpc_pre },
1964 {gpc_g8, gpc_g8, gpc_noop,gpc_noop, gpc_glin,gpc_glin,gpc_lin, gpc_lin },
1965 {gpc_g8b, gpc_g8, gpc_bckc,gpc_noop, gpc_gprq,gpc_gpre,gpc_preq,gpc_pre },
1966 {gpc_sRGB,gpc_sRGB,gpc_sRGB,gpc_sRGB, gpc_noop,gpc_noop,gpc_noop,gpc_noop},
1967 {gpc_b16g,gpc_unpg,gpc_b16c,gpc_unpc, gpc_A, gpc_noop,gpc_A, gpc_noop},
1968 {gpc_sG, gpc_sG, gpc_sRGB,gpc_sRGB, gpc_g16, gpc_g16, gpc_noop,gpc_noop},
1969 {gpc_gb16,gpc_sGp, gpc_cb16,gpc_sCp, gpc_g16, gpc_g16q,gpc_A, gpc_noop}
1972 /* The array is repeated for the cases where both the input and output are color
1973 * mapped because then different algorithms are used.
1975 static void (* const gpc_fn_colormapped[8/*in*/][8/*out*/])
1976 (Pixel *out, const Pixel *in, const Background *back) =
1978 /*out: G-8 GA-8 RGB-8 RGBA-8 G-16 GA-16 RGB-16 RGBA-16 */
1979 {gpc_noop,gpc_noop,gpc_noop,gpc_noop, gpc_lin, gpc_lin, gpc_lin, gpc_lin },
1980 {gpc_bckg,gpc_noop,gpc_bckc,gpc_noop, gpc_preq,gpc_pre, gpc_preq,gpc_pre },
1981 {gpc_g8, gpc_g8, gpc_noop,gpc_noop, gpc_glin,gpc_glin,gpc_lin, gpc_lin },
1982 {gpc_g8b, gpc_g8, gpc_bckc,gpc_noop, gpc_gprq,gpc_gpre,gpc_preq,gpc_pre },
1983 {gpc_sRGB,gpc_sRGB,gpc_sRGB,gpc_sRGB, gpc_noop,gpc_noop,gpc_noop,gpc_noop},
1984 {gpc_b16g,gpc_unpg,gpc_b16c,gpc_unpc, gpc_A, gpc_noop,gpc_A, gpc_noop},
1985 {gpc_sG, gpc_sG, gpc_sRGB,gpc_sRGB, gpc_g16, gpc_g16, gpc_noop,gpc_noop},
1986 {gpc_gb16,gpc_sGp, gpc_cb16,gpc_sCp, gpc_g16, gpc_g16q,gpc_A, gpc_noop}
1989 /* The error arrays record the error in the same matrix; 64 entries, however
1990 * the different algorithms used in libpng for colormap and direct conversions
1991 * mean that four separate matrices are used (for each combination of
1992 * colormapped and direct.)
1994 * In some cases the conversion between sRGB formats goes via a linear
1995 * intermediate; an sRGB to linear conversion (as above) is followed by a simple
1996 * linear to sRGB step with no other conversions. This is done by a separate
1997 * error array from an arbitrary 'in' format to one of the four basic outputs
1998 * (since final output is always sRGB not colormapped).
2000 * These arrays may be modified if the --accumulate flag is set during the run;
2001 * then instead of logging errors they are simply added in.
2003 * The three entries are currently for transparent, partially transparent and
2004 * opaque input pixel values. Notice that alpha should be exact in each case.
2006 * Errors in alpha should only occur when converting from a direct format
2007 * to a colormapped format, when alpha is effectively smashed (so large
2008 * errors can occur.) There should be no error in the '0' and 'opaque'
2009 * values. The fourth entry in the array is used for the alpha error (and it
2010 * should always be zero for the 'via linear' case since this is never color
2013 * Mapping to a colormap smashes the colors, it is necessary to have separate
2014 * values for these cases because they are much larger; it is very much
2015 * impossible to obtain a reasonable result, these are held in
2016 * gpc_error_to_colormap.
2018 #if PNG_FORMAT_FLAG_COLORMAP == 8 /* extra check also required */
2019 # include "pngstest-errors.h" /* machine generated */
2020 #endif /* COLORMAP flag check */
2021 #endif /* flag checks */
2025 /* Basic pixel information: */
2026 Image* in_image; /* Input image */
2027 const Image* out_image; /* Output image */
2029 /* 'background' is the value passed to the gpc_ routines, it may be NULL if
2030 * it should not be used (*this* program has an error if it crashes as a
2033 Background background_color;
2034 const Background* background;
2036 /* Precalculated values: */
2037 int in_opaque; /* Value of input alpha that is opaque */
2038 int is_palette; /* Sample values come from the palette */
2039 int accumulate; /* Accumulate component errors (don't log) */
2040 int output_8bit; /* Output is 8-bit (else 16-bit) */
2042 void (*in_gp)(Pixel*, png_const_voidp);
2043 void (*out_gp)(Pixel*, png_const_voidp);
2045 void (*transform)(Pixel *out, const Pixel *in, const Background *back);
2046 /* A function to perform the required transform */
2048 void (*from_linear)(Pixel *out, const Pixel *in, const Background *back);
2049 /* For 'via_linear' transforms the final, from linear, step, else NULL */
2051 png_uint_16 error[4];
2052 /* Three error values for transparent, partially transparent and opaque
2053 * input pixels (in turn).
2056 png_uint_16 *error_ptr;
2057 /* Where these are stored in the static array (for 'accumulate') */
2061 /* Return a 'transform' as above for the given format conversion. */
2063 transform_from_formats(Transform *result, Image *in_image,
2064 const Image *out_image, png_const_colorp background, int via_linear)
2066 png_uint_32 in_format, out_format;
2067 png_uint_32 in_base, out_base;
2069 memset(result, 0, sizeof *result);
2071 /* Store the original images for error messages */
2072 result->in_image = in_image;
2073 result->out_image = out_image;
2075 in_format = in_image->image.format;
2076 out_format = out_image->image.format;
2078 if (in_format & PNG_FORMAT_FLAG_LINEAR)
2079 result->in_opaque = 65535;
2081 result->in_opaque = 255;
2083 result->output_8bit = (out_format & PNG_FORMAT_FLAG_LINEAR) == 0;
2085 result->is_palette = 0; /* set by caller if required */
2086 result->accumulate = (in_image->opts & ACCUMULATE) != 0;
2088 /* The loaders (which need the ordering information) */
2089 result->in_gp = get_pixel(in_format);
2090 result->out_gp = get_pixel(out_format);
2092 /* Remove the ordering information: */
2093 in_format &= BASE_FORMATS | PNG_FORMAT_FLAG_COLORMAP;
2094 in_base = in_format & BASE_FORMATS;
2095 out_format &= BASE_FORMATS | PNG_FORMAT_FLAG_COLORMAP;
2096 out_base = out_format & BASE_FORMATS;
2100 /* Check for an error in this program: */
2101 if (out_format & (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLORMAP))
2103 fprintf(stderr, "internal transform via linear error 0x%x->0x%x\n",
2104 in_format, out_format);
2108 result->transform = gpc_fn[in_base][out_base | PNG_FORMAT_FLAG_LINEAR];
2109 result->from_linear = gpc_fn[out_base | PNG_FORMAT_FLAG_LINEAR][out_base];
2110 result->error_ptr = gpc_error_via_linear[in_format][out_format];
2113 else if (~in_format & out_format & PNG_FORMAT_FLAG_COLORMAP)
2115 /* The input is not colormapped but the output is, the errors will
2116 * typically be large (only the grayscale-no-alpha case permits preserving
2117 * even 8-bit values.)
2119 result->transform = gpc_fn[in_base][out_base];
2120 result->from_linear = NULL;
2121 result->error_ptr = gpc_error_to_colormap[in_base][out_base];
2126 /* The caller handles the colormap->pixel value conversion, so the
2127 * transform function just gets a pixel value, however because libpng
2128 * currently contains a different implementation for mapping a colormap if
2129 * both input and output are colormapped we need different conversion
2130 * functions to deal with errors in the libpng implementation.
2132 if (in_format & out_format & PNG_FORMAT_FLAG_COLORMAP)
2133 result->transform = gpc_fn_colormapped[in_base][out_base];
2135 result->transform = gpc_fn[in_base][out_base];
2136 result->from_linear = NULL;
2137 result->error_ptr = gpc_error[in_format][out_format];
2140 /* Follow the libpng simplified API rules to work out what to pass to the gpc
2141 * routines as a background value, if one is not required pass NULL so that
2142 * this program crashes in the even of a programming error.
2144 result->background = NULL; /* default: not required */
2146 /* Rule 1: background only need be supplied if alpha is to be removed */
2147 if (in_format & ~out_format & PNG_FORMAT_FLAG_ALPHA)
2149 /* The input value is 'NULL' to use the background and (otherwise) an sRGB
2150 * background color (to use a solid color). The code above uses a fixed
2151 * byte value, BUFFER_INIT8, for buffer even for 16-bit output. For
2152 * linear (16-bit) output the sRGB background color is ignored; the
2153 * composition is always on the background (so BUFFER_INIT8 * 257), except
2154 * that for the colormap (i.e. linear colormapped output) black is used.
2156 result->background = &result->background_color;
2158 if (out_format & PNG_FORMAT_FLAG_LINEAR || via_linear)
2160 if (out_format & PNG_FORMAT_FLAG_COLORMAP)
2162 result->background_color.ir =
2163 result->background_color.ig =
2164 result->background_color.ib = 0;
2165 result->background_color.dr =
2166 result->background_color.dg =
2167 result->background_color.db = 0;
2172 result->background_color.ir =
2173 result->background_color.ig =
2174 result->background_color.ib = BUFFER_INIT8 * 257;
2175 result->background_color.dr =
2176 result->background_color.dg =
2177 result->background_color.db = 0;
2181 else /* sRGB output */
2183 if (background != NULL)
2185 if (out_format & PNG_FORMAT_FLAG_COLOR)
2187 result->background_color.ir = background->red;
2188 result->background_color.ig = background->green;
2189 result->background_color.ib = background->blue;
2190 /* TODO: sometimes libpng uses the power law conversion here, how
2193 result->background_color.dr = sRGB_to_d[background->red];
2194 result->background_color.dg = sRGB_to_d[background->green];
2195 result->background_color.db = sRGB_to_d[background->blue];
2198 else /* grayscale: libpng only looks at 'g' */
2200 result->background_color.ir =
2201 result->background_color.ig =
2202 result->background_color.ib = background->green;
2203 /* TODO: sometimes libpng uses the power law conversion here, how
2206 result->background_color.dr =
2207 result->background_color.dg =
2208 result->background_color.db = sRGB_to_d[background->green];
2212 else if ((out_format & PNG_FORMAT_FLAG_COLORMAP) == 0)
2214 result->background_color.ir =
2215 result->background_color.ig =
2216 result->background_color.ib = BUFFER_INIT8;
2217 /* TODO: sometimes libpng uses the power law conversion here, how
2220 result->background_color.dr =
2221 result->background_color.dg =
2222 result->background_color.db = sRGB_to_d[BUFFER_INIT8];
2225 /* Else the output is colormapped and a background color must be
2226 * provided; if pngstest crashes then that is a bug in this program
2227 * (though libpng should png_error as well.)
2230 result->background = NULL;
2234 if (result->background == NULL)
2236 result->background_color.ir =
2237 result->background_color.ig =
2238 result->background_color.ib = -1; /* not used */
2239 result->background_color.dr =
2240 result->background_color.dg =
2241 result->background_color.db = 1E30; /* not used */
2245 /* Copy the error values into the Transform: */
2246 result->error[0] = result->error_ptr[0];
2247 result->error[1] = result->error_ptr[1];
2248 result->error[2] = result->error_ptr[2];
2249 result->error[3] = result->error_ptr[3];
2253 /* Compare two pixels.
2256 static int error_to_linear = 811; * by experiment *
2257 static int error_to_linear_grayscale = 424; * by experiment *
2258 static int error_to_sRGB = 6; * by experiment *
2259 static int error_to_sRGB_grayscale = 17; * libpng error by calculation +
2261 static int error_in_compose = 2; * by experiment *
2262 static int error_in_premultiply = 1;
2264 * The following is *just* the result of a round trip from 8-bit sRGB to linear
2265 * then back to 8-bit sRGB when it is done by libpng. There are two problems:
2267 * 1) libpng currently uses a 2.2 power law with no linear segment, this results
2268 * in instability in the low values and even with 16-bit precision sRGB(1) ends
2269 * up mapping to sRGB(0) as a result of rounding in the 16-bit representation.
2270 * This gives an error of 1 in the handling of value 1 only.
2272 * 2) libpng currently uses an intermediate 8-bit linear value in gamma
2273 * correction of 8-bit values. This results in many more errors, the worse of
2274 * which is mapping sRGB(14) to sRGB(0).
2276 * The general 'error_via_linear' is more complex because of pre-multiplication,
2277 * this compounds the 8-bit errors according to the alpha value of the pixel.
2278 * As a result 256 values are pre-calculated for error_via_linear.
2281 static int error_in_libpng_gamma;
2282 static int error_via_linear[256]; /* Indexed by 8-bit alpha */
2285 init_error_via_linear(void)
2289 error_via_linear[0] = 255; /* transparent pixel */
2291 for (alpha=1; alpha<=255; ++alpha)
2293 /* 16-bit values less than 128.5 get rounded to 8-bit 0 and so the worst
2294 * case error arises with 16-bit 128.5, work out what sRGB
2295 * (non-associated) value generates 128.5; any value less than this is
2296 * going to map to 0, so the worst error is floor(value).
2298 * Note that errors are considerably higher (more than a factor of 2)
2299 * because libpng uses a simple power law for sRGB data at present.
2301 * Add .1 for arithmetic errors inside libpng.
2303 double v = floor(255*pow(.5/*(128.5 * 255 / 65535)*/ / alpha, 1/2.2)+.1);
2305 error_via_linear[alpha] = (int)v;
2308 /* This is actually 14.99, but, despite the closeness to 15, 14 seems to work
2311 error_in_libpng_gamma = 14;
2316 print_pixel(char string[64], const Pixel *pixel, png_uint_32 format)
2318 switch (format & (PNG_FORMAT_FLAG_ALPHA|PNG_FORMAT_FLAG_COLOR))
2321 sprintf(string, "%s(%d)", format_names[format], pixel->g);
2324 case PNG_FORMAT_FLAG_ALPHA:
2325 sprintf(string, "%s(%d,%d)", format_names[format], pixel->g,
2329 case PNG_FORMAT_FLAG_COLOR:
2330 sprintf(string, "%s(%d,%d,%d)", format_names[format],
2331 pixel->r, pixel->g, pixel->b);
2334 case PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA:
2335 sprintf(string, "%s(%d,%d,%d,%d)", format_names[format],
2336 pixel->r, pixel->g, pixel->b, pixel->a);
2340 sprintf(string, "invalid-format");
2346 logpixel(const Transform *transform, png_uint_32 x, png_uint_32 y,
2347 const Pixel *in, const Pixel *calc, const Pixel *out, const char *reason)
2349 png_uint_32 in_format = transform->in_image->image.format;
2350 png_uint_32 out_format = transform->out_image->image.format;
2352 png_uint_32 back_format = out_format & ~PNG_FORMAT_FLAG_ALPHA;
2353 const char *via_linear = "";
2355 char pixel_in[64], pixel_calc[64], pixel_out[64], pixel_loc[64];
2356 char background_info[100];
2358 print_pixel(pixel_in, in, in_format);
2359 print_pixel(pixel_calc, calc, out_format);
2360 print_pixel(pixel_out, out, out_format);
2362 if (transform->is_palette)
2363 sprintf(pixel_loc, "palette: %lu", (unsigned long)y);
2365 sprintf(pixel_loc, "%lu,%lu", (unsigned long)x, (unsigned long)y);
2367 if (transform->from_linear != NULL)
2369 via_linear = " (via linear)";
2370 /* And as a result the *read* format which did any background processing
2371 * was itself linear, so the background color information is also
2374 back_format |= PNG_FORMAT_FLAG_LINEAR;
2377 if (transform->background != NULL)
2380 char pixel_back[64];
2382 back.r = transform->background->ir;
2383 back.g = transform->background->ig;
2384 back.b = transform->background->ib;
2385 back.a = -1; /* not used */
2387 print_pixel(pixel_back, &back, back_format);
2388 sprintf(background_info, " on background %s", pixel_back);
2392 background_info[0] = 0;
2394 if (transform->in_image->file_name != transform->out_image->file_name)
2396 char error_buffer[512];
2397 sprintf(error_buffer,
2398 "(%s) %s error%s:\n %s%s ->\n %s\n not: %s.\n"
2399 "Use --preserve and examine: ", pixel_loc, reason, via_linear,
2400 pixel_in, background_info, pixel_out, pixel_calc);
2401 return logerror(transform->in_image, transform->in_image->file_name,
2402 error_buffer, transform->out_image->file_name);
2407 char error_buffer[512];
2408 sprintf(error_buffer,
2409 "(%s) %s error%s:\n %s%s ->\n %s\n not: %s.\n"
2410 " The error happened when reading the original file with this format.",
2411 pixel_loc, reason, via_linear, pixel_in, background_info, pixel_out,
2413 return logerror(transform->in_image, transform->in_image->file_name,
2419 cmppixel(Transform *transform, png_const_voidp in, png_const_voidp out,
2420 png_uint_32 x, png_uint_32 y/*or palette index*/)
2423 png_const_charp errmsg;
2424 Pixel pixel_in, pixel_calc, pixel_out;
2426 transform->in_gp(&pixel_in, in);
2428 if (transform->from_linear == NULL)
2429 transform->transform(&pixel_calc, &pixel_in, transform->background);
2433 transform->transform(&pixel_out, &pixel_in, transform->background);
2434 transform->from_linear(&pixel_calc, &pixel_out, NULL);
2437 transform->out_gp(&pixel_out, out);
2439 /* Eliminate the case where the input and output values match exactly. */
2440 if (pixel_calc.a == pixel_out.a && pixel_calc.r == pixel_out.r &&
2441 pixel_calc.g == pixel_out.g && pixel_calc.b == pixel_out.b)
2444 /* Eliminate the case where the output pixel is transparent and the output
2445 * is 8-bit - any component values are valid. Don't check the input alpha
2446 * here to also skip the 16-bit small alpha cases.
2448 if (transform->output_8bit && pixel_calc.a == 0 && pixel_out.a == 0)
2451 /* Check for alpha errors first; an alpha error can damage the components too
2452 * so avoid spurious checks on components if one is found.
2456 int err_a = abs(pixel_calc.a-pixel_out.a);
2458 if (err_a > transform->error[3])
2460 /* If accumulating check the components too */
2461 if (transform->accumulate)
2462 transform->error[3] = (png_uint_16)err_a;
2469 /* Now if *either* of the output alphas are 0 but alpha is within tolerance
2470 * eliminate the 8-bit component comparison.
2472 if (errmsg == NULL && transform->output_8bit &&
2473 (pixel_calc.a == 0 || pixel_out.a == 0))
2476 if (errmsg == NULL) /* else just signal an alpha error */
2478 int err_r = abs(pixel_calc.r - pixel_out.r);
2479 int err_g = abs(pixel_calc.g - pixel_out.g);
2480 int err_b = abs(pixel_calc.b - pixel_out.b);
2483 if ((err_r | err_g | err_b) == 0)
2484 return 1; /* exact match */
2486 /* Mismatch on a component, check the input alpha */
2487 if (pixel_in.a >= transform->in_opaque)
2489 errmsg = "opaque component";
2490 limit = 2; /* opaque */
2493 else if (pixel_in.a > 0)
2495 errmsg = "alpha component";
2496 limit = 1; /* partially transparent */
2501 errmsg = "transparent component (background)";
2502 limit = 0; /* transparent */
2506 if (maxerr < err_g) maxerr = err_g;
2507 if (maxerr < err_b) maxerr = err_b;
2509 if (maxerr <= transform->error[limit])
2510 return 1; /* within the error limits */
2512 /* Handle a component mis-match; log it, just return an error code, or
2515 if (transform->accumulate)
2517 transform->error[limit] = (png_uint_16)maxerr;
2518 return 1; /* to cause the caller to keep going */
2522 /* Failure to match and not accumulating, so the error must be logged. */
2523 return logpixel(transform, x, y, &pixel_in, &pixel_calc, &pixel_out, errmsg);
2527 component_loc(png_byte loc[4], png_uint_32 format)
2529 /* Given a format return the number of channels and the location of
2532 * The mask 'loc' contains the component offset of the channels in the
2533 * following order. Note that if 'format' is grayscale the entries 1-3 must
2534 * all contain the location of the gray channel.
2543 if (format & PNG_FORMAT_FLAG_COLOR)
2549 # ifdef PNG_FORMAT_BGR_SUPPORTED
2550 if (format & PNG_FORMAT_FLAG_BGR)
2567 loc[1] = loc[2] = loc[3] = 0;
2570 if (format & PNG_FORMAT_FLAG_ALPHA)
2572 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
2573 if (format & PNG_FORMAT_FLAG_AFIRST)
2589 loc[0] = 4; /* not present */
2594 /* Compare two images, the original 'a', which was written out then read back in
2595 * to * give image 'b'. The formats may have been changed.
2598 compare_two_images(Image *a, Image *b, int via_linear,
2599 png_const_colorp background)
2601 ptrdiff_t stridea = a->stride;
2602 ptrdiff_t strideb = b->stride;
2603 png_const_bytep rowa = a->buffer+16;
2604 png_const_bytep rowb = b->buffer+16;
2605 png_uint_32 width = a->image.width;
2606 png_uint_32 height = a->image.height;
2607 png_uint_32 formata = a->image.format;
2608 png_uint_32 formatb = b->image.format;
2609 unsigned int a_sample = PNG_IMAGE_SAMPLE_SIZE(formata);
2610 unsigned int b_sample = PNG_IMAGE_SAMPLE_SIZE(formatb);
2611 int alpha_added, alpha_removed;
2615 int btoa[4]={0,0,0,0};
2617 /* This should never happen: */
2618 if (width != b->image.width || height != b->image.height)
2619 return logerror(a, a->file_name, ": width x height changed: ",
2622 /* Set up the background and the transform */
2623 transform_from_formats(&tr, a, b, background, via_linear);
2625 /* Find the first row and inter-row space. */
2626 if (!(formata & PNG_FORMAT_FLAG_COLORMAP) &&
2627 (formata & PNG_FORMAT_FLAG_LINEAR))
2630 if (!(formatb & PNG_FORMAT_FLAG_COLORMAP) &&
2631 (formatb & PNG_FORMAT_FLAG_LINEAR))
2634 if (stridea < 0) rowa += (height-1) * (-stridea);
2635 if (strideb < 0) rowb += (height-1) * (-strideb);
2637 /* First shortcut the two colormap case by comparing the image data; if it
2638 * matches then we expect the colormaps to match, although this is not
2639 * absolutely necessary for an image match. If the colormaps fail to match
2640 * then there is a problem in libpng.
2642 if (formata & formatb & PNG_FORMAT_FLAG_COLORMAP)
2644 /* Only check colormap entries that actually exist; */
2645 png_const_bytep ppa, ppb;
2647 png_byte in_use[256], amax = 0, bmax = 0;
2649 memset(in_use, 0, sizeof in_use);
2654 /* Do this the slow way to accumulate the 'in_use' flags, don't break out
2655 * of the loop until the end; this validates the color-mapped data to
2656 * ensure all pixels are valid color-map indexes.
2658 for (y=0, match=1; y<height && match; ++y, ppa += stridea, ppb += strideb)
2662 for (x=0; x<width; ++x)
2664 png_byte bval = ppb[x];
2665 png_byte aval = ppa[x];
2679 /* If the buffers match then the colormaps must too. */
2682 /* Do the color-maps match, entry by entry? Only check the 'in_use'
2683 * entries. An error here should be logged as a color-map error.
2685 png_const_bytep a_cmap = (png_const_bytep)a->colormap;
2686 png_const_bytep b_cmap = (png_const_bytep)b->colormap;
2687 int result = 1; /* match by default */
2689 /* This is used in logpixel to get the error message correct. */
2692 for (y=0; y<256; ++y, a_cmap += a_sample, b_cmap += b_sample)
2695 /* The colormap entries should be valid, but because libpng doesn't
2696 * do any checking at present the original image may contain invalid
2697 * pixel values. These cause an error here (at present) unless
2698 * accumulating errors in which case the program just ignores them.
2700 if (y >= a->image.colormap_entries)
2702 if ((a->opts & ACCUMULATE) == 0)
2705 sprintf(pindex, "%lu[%lu]", (unsigned long)y,
2706 (unsigned long)a->image.colormap_entries);
2707 logerror(a, a->file_name, ": bad pixel index: ", pindex);
2712 else if (y >= b->image.colormap_entries)
2714 if ((b->opts & ACCUMULATE) == 0)
2717 sprintf(pindex, "%lu[%lu]", (unsigned long)y,
2718 (unsigned long)b->image.colormap_entries);
2719 logerror(b, b->file_name, ": bad pixel index: ", pindex);
2724 /* All the mismatches are logged here; there can only be 256! */
2725 else if (!cmppixel(&tr, a_cmap, b_cmap, 0, y))
2729 /* If requested, copy the error values back from the Transform. */
2730 if (a->opts & ACCUMULATE)
2732 tr.error_ptr[0] = tr.error[0];
2733 tr.error_ptr[1] = tr.error[1];
2734 tr.error_ptr[2] = tr.error[2];
2735 tr.error_ptr[3] = tr.error[3];
2736 result = 1; /* force a continue */
2742 /* else the image buffers don't match pixel-wise so compare sample values
2743 * instead, but first validate that the pixel indexes are in range (but
2744 * only if not accumulating, when the error is ignored.)
2746 else if ((a->opts & ACCUMULATE) == 0)
2749 # define BYTE_CHARS 20 /* 2^32: GCC sprintf warning */
2751 # define BYTE_CHARS 3 /* 2^8: real maximum value */
2753 /* Check the original image first,
2754 * TODO: deal with input images with bad pixel values?
2756 if (amax >= a->image.colormap_entries)
2758 char pindex[3+2*BYTE_CHARS];
2759 sprintf(pindex, "%d[%u]", amax,
2760 (png_byte)/*SAFE*/a->image.colormap_entries);
2761 return logerror(a, a->file_name, ": bad pixel index: ", pindex);
2764 else if (bmax >= b->image.colormap_entries)
2766 char pindex[3+2*BYTE_CHARS];
2767 sprintf(pindex, "%d[%u]", bmax,
2768 (png_byte)/*SAFE*/b->image.colormap_entries);
2769 return logerror(b, b->file_name, ": bad pixel index: ", pindex);
2774 /* We can directly compare pixel values without the need to use the read
2775 * or transform support (i.e. a memory compare) if:
2777 * 1) The bit depth has not changed.
2778 * 2) RGB to grayscale has not been done (the reverse is ok; we just compare
2779 * the three RGB values to the original grayscale.)
2780 * 3) An alpha channel has not been removed from an 8-bit format, or the
2781 * 8-bit alpha value of the pixel was 255 (opaque).
2783 * If an alpha channel has been *added* then it must have the relevant opaque
2784 * value (255 or 65535).
2786 * The fist two the tests (in the order given above) (using the boolean
2787 * equivalence !a && !b == !(a || b))
2789 if (!(((formata ^ formatb) & PNG_FORMAT_FLAG_LINEAR) |
2790 (formata & (formatb ^ PNG_FORMAT_FLAG_COLOR) & PNG_FORMAT_FLAG_COLOR)))
2792 /* Was an alpha channel changed? */
2793 png_uint_32 alpha_changed = (formata ^ formatb) & PNG_FORMAT_FLAG_ALPHA;
2795 /* Was an alpha channel removed? (The third test.) If so the direct
2796 * comparison is only possible if the input alpha is opaque.
2798 alpha_removed = (formata & alpha_changed) != 0;
2800 /* Was an alpha channel added? */
2801 alpha_added = (formatb & alpha_changed) != 0;
2803 /* The channels may have been moved between input and output, this finds
2804 * out how, recording the result in the btoa array, which says where in
2805 * 'a' to find each channel of 'b'. If alpha was added then btoa[alpha]
2806 * ends up as 4 (and is not used.)
2813 /* The following are used only if the formats match, except that
2814 * 'bchannels' is a flag for matching formats. btoa[x] says, for each
2815 * channel in b, where to find the corresponding value in a, for the
2816 * bchannels. achannels may be different for a gray to rgb transform
2817 * (a will be 1 or 2, b will be 3 or 4 channels.)
2819 (void)component_loc(aloc, formata);
2820 bchannels = component_loc(bloc, formatb);
2822 /* Hence the btoa array. */
2823 for (i=0; i<4; ++i) if (bloc[i] < 4)
2824 btoa[bloc[i]] = aloc[i]; /* may be '4' for alpha */
2827 alpha_added = bloc[0]; /* location of alpha channel in image b */
2830 alpha_added = 4; /* Won't match an image b channel */
2833 alpha_removed = aloc[0]; /* location of alpha channel in image a */
2842 /* Direct compare is not possible, cancel out all the corresponding local
2846 alpha_removed = alpha_added = 4;
2847 btoa[3] = btoa[2] = btoa[1] = btoa[0] = 4; /* 4 == not present */
2850 for (y=0; y<height; ++y, rowa += stridea, rowb += strideb)
2852 png_const_bytep ppa, ppb;
2855 for (x=0, ppa=rowa, ppb=rowb; x<width; ++x)
2857 png_const_bytep psa, psb;
2859 if (formata & PNG_FORMAT_FLAG_COLORMAP)
2860 psa = (png_const_bytep)a->colormap + a_sample * *ppa++;
2862 psa = ppa, ppa += a_sample;
2864 if (formatb & PNG_FORMAT_FLAG_COLORMAP)
2865 psb = (png_const_bytep)b->colormap + b_sample * *ppb++;
2867 psb = ppb, ppb += b_sample;
2869 /* Do the fast test if possible. */
2872 /* Check each 'b' channel against either the corresponding 'a'
2873 * channel or the opaque alpha value, as appropriate. If
2874 * alpha_removed value is set (not 4) then also do this only if the
2875 * 'a' alpha channel (alpha_removed) is opaque; only relevant for
2878 if (formatb & PNG_FORMAT_FLAG_LINEAR) /* 16-bit checks */
2880 png_const_uint_16p pua = aligncastconst(png_const_uint_16p, psa);
2881 png_const_uint_16p pub = aligncastconst(png_const_uint_16p, psb);
2886 if (pua[btoa[3]] != pub[3]) break;
2889 if (pua[btoa[2]] != pub[2]) break;
2892 if (pua[btoa[1]] != pub[1]) break;
2895 if (pua[btoa[0]] != pub[0]) break;
2896 if (alpha_added != 4 && pub[alpha_added] != 65535) break;
2897 continue; /* x loop */
2899 break; /* impossible */
2903 else if (alpha_removed == 4 || psa[alpha_removed] == 255)
2908 if (psa[btoa[3]] != psb[3]) break;
2911 if (psa[btoa[2]] != psb[2]) break;
2914 if (psa[btoa[1]] != psb[1]) break;
2917 if (psa[btoa[0]] != psb[0]) break;
2918 if (alpha_added != 4 && psb[alpha_added] != 255) break;
2919 continue; /* x loop */
2921 break; /* impossible */
2926 /* If we get to here the fast match failed; do the slow match for this
2929 if (!cmppixel(&tr, psa, psb, x, y) && (a->opts & KEEP_GOING) == 0)
2930 return 0; /* error case */
2934 /* If requested, copy the error values back from the Transform. */
2935 if (a->opts & ACCUMULATE)
2937 tr.error_ptr[0] = tr.error[0];
2938 tr.error_ptr[1] = tr.error[1];
2939 tr.error_ptr[2] = tr.error[2];
2940 tr.error_ptr[3] = tr.error[3];
2946 /* Read the file; how the read gets done depends on which of input_file and
2947 * input_memory have been set.
2950 read_file(Image *image, png_uint_32 format, png_const_colorp background)
2952 memset(&image->image, 0, sizeof image->image);
2953 image->image.version = PNG_IMAGE_VERSION;
2955 if (image->input_memory != NULL)
2957 if (!png_image_begin_read_from_memory(&image->image, image->input_memory,
2958 image->input_memory_size))
2959 return logerror(image, "memory init: ", image->file_name, "");
2962 # ifdef PNG_STDIO_SUPPORTED
2963 else if (image->input_file != NULL)
2965 if (!png_image_begin_read_from_stdio(&image->image, image->input_file))
2966 return logerror(image, "stdio init: ", image->file_name, "");
2971 if (!png_image_begin_read_from_file(&image->image, image->file_name))
2972 return logerror(image, "file init: ", image->file_name, "");
2977 return logerror(image, "unsupported file/stdio init: ",
2978 image->file_name, "");
2982 /* This must be set after the begin_read call: */
2983 if (image->opts & sRGB_16BIT)
2984 image->image.flags |= PNG_IMAGE_FLAG_16BIT_sRGB;
2986 /* Have an initialized image with all the data we need plus, maybe, an
2987 * allocated file (myfile) or buffer (mybuffer) that need to be freed.
2991 png_uint_32 image_format;
2993 /* Print both original and output formats. */
2994 image_format = image->image.format;
2996 if (image->opts & VERBOSE)
2998 printf("%s %lu x %lu %s -> %s", image->file_name,
2999 (unsigned long)image->image.width,
3000 (unsigned long)image->image.height,
3001 format_names[image_format & FORMAT_MASK],
3002 (format & FORMAT_NO_CHANGE) != 0 || image->image.format == format
3003 ? "no change" : format_names[format & FORMAT_MASK]);
3005 if (background != NULL)
3006 printf(" background(%d,%d,%d)\n", background->red,
3007 background->green, background->blue);
3014 /* 'NO_CHANGE' combined with the color-map flag forces the base format
3015 * flags to be set on read to ensure that the original representation is
3016 * not lost in the pass through a colormap format.
3018 if ((format & FORMAT_NO_CHANGE) != 0)
3020 if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0 &&
3021 (image_format & PNG_FORMAT_FLAG_COLORMAP) != 0)
3022 format = (image_format & ~BASE_FORMATS) | (format & BASE_FORMATS);
3025 format = image_format;
3028 image->image.format = format;
3030 image->stride = PNG_IMAGE_ROW_STRIDE(image->image) + image->stride_extra;
3033 result = png_image_finish_read(&image->image, background,
3034 image->buffer+16, (png_int_32)image->stride, image->colormap);
3036 checkbuffer(image, image->file_name);
3039 return checkopaque(image);
3042 return logerror(image, image->file_name, ": image read failed", "");
3046 /* Reads from a filename, which must be in image->file_name, but uses
3047 * image->opts to choose the method. The file is always read in its native
3048 * format (the one the simplified API suggests).
3051 read_one_file(Image *image)
3053 if (!(image->opts & USE_FILE) || (image->opts & USE_STDIO))
3055 /* memory or stdio. */
3056 FILE *f = fopen(image->file_name, "rb");
3060 if (image->opts & USE_FILE)
3061 image->input_file = f;
3065 if (fseek(f, 0, SEEK_END) == 0)
3067 long int cb = ftell(f);
3071 #ifndef __COVERITY__
3072 if ((unsigned long int)cb <= (size_t)~(size_t)0)
3075 png_bytep b = voidcast(png_bytep, malloc((size_t)cb));
3081 if (fread(b, (size_t)cb, 1, f) == 1)
3084 image->input_memory_size = cb;
3085 image->input_memory = b;
3091 return logclose(image, f, image->file_name,
3097 return logclose(image, f, image->file_name,
3098 ": out of memory: ");
3102 return logclose(image, f, image->file_name,
3103 ": file too big for this architecture: ");
3104 /* cb is the length of the file as a (long) and
3105 * this is greater than the maximum amount of
3106 * memory that can be requested from malloc.
3111 return logclose(image, f, image->file_name,
3115 return logclose(image, f, image->file_name,
3120 return logclose(image, f, image->file_name, ": seek failed: ");
3125 return logerror(image, image->file_name, ": open failed: ",
3129 return read_file(image, FORMAT_NO_CHANGE, NULL);
3132 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
3134 write_one_file(Image *output, Image *image, int convert_to_8bit)
3136 if (image->opts & FAST_WRITE)
3137 image->image.flags |= PNG_IMAGE_FLAG_FAST;
3139 if (image->opts & USE_STDIO)
3141 #ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
3142 #ifndef __COVERITY__
3143 FILE *f = tmpfile();
3145 /* Experimental. Coverity says tmpfile() is insecure because it
3146 * generates predictable names.
3148 * It is possible to satisfy Coverity by using mkstemp(); however,
3149 * any platform supporting mkstemp() undoubtedly has a secure tmpfile()
3150 * implementation as well, and doesn't need the fix. Note that
3151 * the fix won't work on platforms that don't support mkstemp().
3153 * https://www.securecoding.cert.org/confluence/display/c/
3154 * FIO21-C.+Do+not+create+temporary+files+in+shared+directories
3155 * says that most historic implementations of tmpfile() provide
3156 * only a limited number of possible temporary file names
3157 * (usually 26) before file names are recycled. That article also
3158 * provides a secure solution that unfortunately depends upon mkstemp().
3160 char tmpfile[] = "pngstest-XXXXXX";
3164 filedes = mkstemp(tmpfile);
3169 f = fdopen(filedes,"w+");
3170 /* Hide the filename immediately and ensure that the file does
3171 * not exist after the program ends
3173 (void) unlink(tmpfile);
3179 if (png_image_write_to_stdio(&image->image, f, convert_to_8bit,
3180 image->buffer+16, (png_int_32)image->stride, image->colormap))
3185 initimage(output, image->opts, "tmpfile", image->stride_extra);
3186 output->input_file = f;
3187 if (!checkopaque(image))
3192 return logclose(image, f, "tmpfile", ": flush: ");
3198 return logerror(image, "tmpfile", ": write failed", "");
3203 return logerror(image, "tmpfile", ": open: ", strerror(errno));
3204 #else /* SIMPLIFIED_WRITE_STDIO */
3205 return logerror(image, "tmpfile", ": open: unsupported", "");
3206 #endif /* SIMPLIFIED_WRITE_STDIO */
3209 else if (image->opts & USE_FILE)
3211 #ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
3212 static int counter = 0;
3215 sprintf(name, "%s%d.png", tmpf, ++counter);
3217 if (png_image_write_to_file(&image->image, name, convert_to_8bit,
3218 image->buffer+16, (png_int_32)image->stride, image->colormap))
3220 initimage(output, image->opts, output->tmpfile_name,
3221 image->stride_extra);
3222 /* Afterwards, or freeimage will delete it! */
3223 strcpy(output->tmpfile_name, name);
3225 if (!checkopaque(image))
3230 return logerror(image, name, ": write failed", "");
3231 #else /* SIMPLIFIED_WRITE_STDIO */
3232 return logerror(image, "stdio", ": open: unsupported", "");
3233 #endif /* SIMPLIFIED_WRITE_STDIO */
3236 else /* use memory */
3238 png_alloc_size_t size;
3240 if (png_image_write_get_memory_size(image->image, size, convert_to_8bit,
3241 image->buffer+16, (png_int_32)image->stride, image->colormap))
3243 /* This is non-fatal but ignoring it was causing serious problems in
3244 * the macro to be ignored:
3246 if (size > PNG_IMAGE_PNG_SIZE_MAX(image->image))
3247 return logerror(image, "memory", ": PNG_IMAGE_SIZE_MAX wrong", "");
3249 initimage(output, image->opts, "memory", image->stride_extra);
3250 output->input_memory = malloc(size);
3252 if (output->input_memory != NULL)
3254 output->input_memory_size = size;
3256 if (png_image_write_to_memory(&image->image, output->input_memory,
3257 &output->input_memory_size, convert_to_8bit, image->buffer+16,
3258 (png_int_32)image->stride, image->colormap))
3260 /* This is also non-fatal but it safes safer to error out anyway:
3262 if (size != output->input_memory_size)
3263 return logerror(image, "memory", ": memory size wrong", "");
3267 return logerror(image, "memory", ": write failed", "");
3271 return logerror(image, "memory", ": out of memory", "");
3275 return logerror(image, "memory", ": get size:", "");
3278 /* 'output' has an initialized temporary image, read this back in and compare
3279 * this against the original: there should be no change since the original
3280 * format was written unmodified unless 'convert_to_8bit' was specified.
3281 * However, if the original image was color-mapped, a simple read will zap
3282 * the linear, color and maybe alpha flags, this will cause spurious failures
3283 * under some circumstances.
3285 if (read_file(output, image->image.format | FORMAT_NO_CHANGE, NULL))
3287 png_uint_32 original_format = image->image.format;
3289 if (convert_to_8bit)
3290 original_format &= ~PNG_FORMAT_FLAG_LINEAR;
3292 if ((output->image.format & BASE_FORMATS) !=
3293 (original_format & BASE_FORMATS))
3294 return logerror(image, image->file_name, ": format changed on read: ",
3297 return compare_two_images(image, output, 0/*via linear*/, NULL);
3301 return logerror(output, output->tmpfile_name,
3302 ": read of new file failed", "");
3307 testimage(Image *image, png_uint_32 opts, format_list *pf)
3312 /* Copy the original data, stealing it from 'image' */
3321 image->input_file = NULL;
3322 image->input_memory = NULL;
3323 image->input_memory_size = 0;
3324 image->tmpfile_name[0] = 0;
3327 png_uint_32 counter;
3334 /* Use the low bit of 'counter' to indicate whether or not to do alpha
3335 * removal with a background color or by composting onto the image; this
3336 * step gets skipped if it isn't relevant
3338 for (counter=0; counter<2*FORMAT_COUNT; ++counter)
3339 if (format_isset(pf, counter >> 1))
3341 png_uint_32 format = counter >> 1;
3343 png_color background_color;
3344 png_colorp background = NULL;
3346 /* If there is a format change that removes the alpha channel then
3347 * the background is relevant. If the output is 8-bit color-mapped
3348 * then a background color *must* be provided, otherwise there are
3349 * two tests to do - one with a color, the other with NULL. The
3350 * NULL test happens second.
3352 if ((counter & 1) == 0)
3354 if ((format & PNG_FORMAT_FLAG_ALPHA) == 0 &&
3355 (image->image.format & PNG_FORMAT_FLAG_ALPHA) != 0)
3357 /* Alpha/transparency will be removed, the background is
3358 * relevant: make it a color the first time
3360 random_color(&background_color);
3361 background = &background_color;
3363 /* BUT if the output is to a color-mapped 8-bit format then
3364 * the background must always be a color, so increment 'counter'
3365 * to skip the NULL test.
3367 if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0 &&
3368 (format & PNG_FORMAT_FLAG_LINEAR) == 0)
3372 /* Otherwise an alpha channel is not being eliminated, just leave
3373 * background NULL and skip the (counter & 1) NULL test.
3378 /* else just use NULL for background */
3381 copy.opts = opts; /* in case read_file needs to change it */
3383 result = read_file(©, format, background);
3387 /* Make sure the file just read matches the original file. */
3388 result = compare_two_images(image, ©, 0/*via linear*/, background);
3392 # ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
3393 /* Write the *copy* just made to a new file to make sure the write
3394 * side works ok. Check the conversion to sRGB if the copy is
3398 result = write_one_file(&output, ©, 0/*convert to 8bit*/);
3402 /* Validate against the original too; the background is needed here
3403 * as well so that compare_two_images knows what color was used.
3405 result = compare_two_images(image, &output, 0, background);
3409 if ((format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
3410 (format & PNG_FORMAT_FLAG_COLORMAP) == 0)
3412 /* 'output' is linear, convert to the corresponding sRGB format.
3415 result = write_one_file(&output, ©, 1/*convert to 8bit*/);
3419 /* This may involve a conversion via linear; in the ideal world
3420 * this would round-trip correctly, but libpng 1.5.7 is not the
3421 * ideal world so allow a drift (error_via_linear).
3423 * 'image' has an alpha channel but 'output' does not then there
3424 * will a strip-alpha-channel operation (because 'output' is
3425 * linear), handle this by composing on black when doing the
3428 result = compare_two_images(image, &output, 1/*via_linear*/,
3433 # endif /* PNG_SIMPLIFIED_WRITE_SUPPORTED */
3445 test_one_file(const char *file_name, format_list *formats, png_uint_32 opts,
3446 int stride_extra, int log_pass)
3451 if (!(opts & NO_RESEED))
3452 reseed(); /* ensure that the random numbers don't depend on file order */
3454 initimage(&image, opts, file_name, stride_extra);
3455 result = read_one_file(&image);
3457 result = testimage(&image, opts, formats);
3460 /* Ensure that stderr is flushed into any log file */
3471 # ifndef PNG_SIMPLIFIED_WRITE_SUPPORTED
3472 printf(" (no write)");
3476 printf(" %s\n", file_name);
3477 /* stdout may not be line-buffered if it is piped to a file, so: */
3488 main(int argc, char **argv)
3490 png_uint_32 opts = FAST_WRITE | STRICT;
3491 format_list formats;
3492 const char *touch = NULL;
3495 int stride_extra = 0;
3499 #if PNG_LIBPNG_VER >= 10700
3500 /* This error should not exist in 1.7 or later: */
3506 init_error_via_linear();
3508 format_init(&formats);
3509 reseed(); /* initialize random number seeds */
3511 for (c=1; c<argc; ++c)
3513 const char *arg = argv[c];
3515 if (strcmp(arg, "--log") == 0)
3517 else if (strcmp(arg, "--fresh") == 0)
3519 memset(gpc_error, 0, sizeof gpc_error);
3520 memset(gpc_error_via_linear, 0, sizeof gpc_error_via_linear);
3522 else if (strcmp(arg, "--file") == 0)
3523 # ifdef PNG_STDIO_SUPPORTED
3526 return SKIP; /* skipped: no support */
3528 else if (strcmp(arg, "--memory") == 0)
3530 else if (strcmp(arg, "--stdio") == 0)
3531 # ifdef PNG_STDIO_SUPPORTED
3534 return SKIP; /* skipped: no support */
3536 else if (strcmp(arg, "--name") == 0)
3538 else if (strcmp(arg, "--verbose") == 0)
3540 else if (strcmp(arg, "--quiet") == 0)
3542 else if (strcmp(arg, "--preserve") == 0)
3543 opts |= KEEP_TMPFILES;
3544 else if (strcmp(arg, "--nopreserve") == 0)
3545 opts &= ~KEEP_TMPFILES;
3546 else if (strcmp(arg, "--keep-going") == 0)
3548 else if (strcmp(arg, "--fast") == 0)
3550 else if (strcmp(arg, "--slow") == 0)
3551 opts &= ~FAST_WRITE;
3552 else if (strcmp(arg, "--accumulate") == 0)
3554 else if (strcmp(arg, "--redundant") == 0)
3556 else if (strcmp(arg, "--stop") == 0)
3557 opts &= ~KEEP_GOING;
3558 else if (strcmp(arg, "--strict") == 0)
3560 else if (strcmp(arg, "--nostrict") == 0)
3562 else if (strcmp(arg, "--sRGB-16bit") == 0)
3564 else if (strcmp(arg, "--linear-16bit") == 0)
3565 opts &= ~sRGB_16BIT;
3566 else if (strcmp(arg, "--noreseed") == 0)
3568 else if (strcmp(arg, "--fault-gbg-warning") == 0)
3570 else if (strcmp(arg, "--tmpfile") == 0)
3574 if (strlen(argv[++c]) >= sizeof tmpf)
3577 fprintf(stderr, "%s: %s is too long for a temp file prefix\n",
3582 /* Safe: checked above */
3583 strncpy(tmpf, argv[c], sizeof (tmpf)-1);
3589 fprintf(stderr, "%s: %s requires a temporary file prefix\n",
3594 else if (strcmp(arg, "--touch") == 0)
3602 fprintf(stderr, "%s: %s requires a file name argument\n",
3607 else if (arg[0] == '+')
3609 png_uint_32 format = formatof(arg+1);
3611 if (format > FORMAT_COUNT)
3614 format_set(&formats, format);
3616 else if (arg[0] == '-' && arg[1] != 0 && (arg[1] != '0' || arg[2] != 0))
3619 fprintf(stderr, "%s: unknown option: %s\n", argv[0], arg);
3624 if (format_is_initial(&formats))
3625 format_default(&formats, redundant);
3629 int term = (arg[1] == '0' ? 0 : '\n');
3630 unsigned int ich = 0;
3632 /* Loop reading files, use a static buffer to simplify this and just
3633 * stop if the name gets to long.
3635 static char buffer[4096];
3641 /* Don't allow '\0' in file names, and terminate with '\n' or,
3642 * for -0, just '\0' (use -print0 to find to make this work!)
3644 if (ch == EOF || ch == term || ch == 0)
3648 if (ich > 0 && !test_one_file(buffer, &formats, opts,
3649 stride_extra, log_pass))
3656 --ich; /* so that the increment below sets it to 0 again */
3660 buffer[ich] = (char)ch;
3661 } while (++ich < sizeof buffer);
3667 fprintf(stderr, "%s...%s: file name too long\n", buffer,
3673 else if (!test_one_file(arg, &formats, opts, stride_extra, log_pass))
3678 if (opts & ACCUMULATE)
3682 printf("/* contrib/libtests/pngstest-errors.h\n");
3684 printf(" * BUILT USING:" PNG_HEADER_VERSION_STRING);
3686 printf(" * This code is released under the libpng license.\n");
3687 printf(" * For conditions of distribution and use, see the disclaimer\n");
3688 printf(" * and license in png.h\n");
3690 printf(" * THIS IS A MACHINE GENERATED FILE: do not edit it directly!\n");
3691 printf(" * Instead run:\n");
3693 printf(" * pngstest --accumulate\n");
3695 printf(" * on as many PNG files as possible; at least PNGSuite and\n");
3696 printf(" * contrib/libtests/testpngs.\n");
3699 printf("static png_uint_16 gpc_error[16/*in*/][16/*out*/][4/*a*/] =\n");
3701 for (in=0; in<16; ++in)
3704 printf(" { /* input: %s */\n ", format_names[in]);
3705 for (out=0; out<16; ++out)
3709 for (alpha=0; alpha<4; ++alpha)
3711 printf(" %d", gpc_error[in][out][alpha]);
3712 if (alpha < 3) putchar(',');
3718 if (out % 4 == 3) printf("\n ");
3730 printf("static png_uint_16 gpc_error_via_linear[16][4/*out*/][4] =\n");
3732 for (in=0; in<16; ++in)
3735 printf(" { /* input: %s */\n ", format_names[in]);
3736 for (out=0; out<4; ++out)
3740 for (alpha=0; alpha<4; ++alpha)
3742 printf(" %d", gpc_error_via_linear[in][out][alpha]);
3743 if (alpha < 3) putchar(',');
3758 printf("static png_uint_16 gpc_error_to_colormap[8/*i*/][8/*o*/][4] =\n");
3760 for (in=0; in<8; ++in)
3763 printf(" { /* input: %s */\n ", format_names[in]);
3764 for (out=0; out<8; ++out)
3768 for (alpha=0; alpha<4; ++alpha)
3770 printf(" %d", gpc_error_to_colormap[in][out][alpha]);
3771 if (alpha < 3) putchar(',');
3777 if (out % 4 == 3) printf("\n ");
3788 printf("/* END MACHINE GENERATED */\n");
3791 if (retval == 0 && touch != NULL)
3793 FILE *fsuccess = fopen(touch, "wt");
3795 if (fsuccess != NULL)
3798 fprintf(fsuccess, "PNG simple API tests succeeded\n");
3800 error = ferror(fsuccess);
3802 if (fclose(fsuccess) || error)
3805 fprintf(stderr, "%s: write failed\n", touch);
3813 fprintf(stderr, "%s: open failed\n", touch);
3821 #else /* !PNG_SIMPLIFIED_READ_SUPPORTED */
3824 fprintf(stderr, "pngstest: no read support in libpng, test skipped\n");
3825 /* So the test is skipped: */
3828 #endif /* PNG_SIMPLIFIED_READ_SUPPORTED */