4 * Copyright (c) 2021 Cosmin Truta
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.
14 #define _ISOC90_SOURCE 1
15 #define MALLOC_CHECK_ 2 /*glibc facility: turn on debugging*/
25 #if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
29 /* Define the following to use this test against your installed libpng, rather
30 * than the one being built here:
32 #ifdef PNG_FREESTANDING_TESTS
35 # include "../../png.h"
38 /* 1.6.1 added support for the configure test harness, which uses 77 to indicate
39 * a skipped test, in earlier versions we need to succeed on a skipped test, so:
41 #if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
47 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED /* Else nothing can be done */
48 #include "../tools/sRGB.h"
52 * These defines switch on alternate algorithms for format conversions to match
53 * the current libpng implementation; they are set to allow pngstest to pass
54 * even though libpng is producing answers that are not as correct as they
57 #define ALLOW_UNUSED_GPC 0
58 /* If true include unused static GPC functions and declare an external array
59 * of them to hide the fact that they are unused. This is for development
60 * use while testing the correct function to use to take into account libpng
61 * misbehavior, such as using a simple power law to correct sRGB to linear.
64 /* The following is to support direct compilation of this file as C++ */
66 # define voidcast(type, value) static_cast<type>(value)
67 # define aligncastconst(type, value) \
68 static_cast<type>(static_cast<const void*>(value))
70 # define voidcast(type, value) (value)
71 # define aligncastconst(type, value) ((const void*)(value))
72 #endif /* __cplusplus */
74 /* During parallel runs of pngstest each temporary file needs a unique name,
75 * this is used to permit uniqueness using a command line argument which can be
76 * up to 22 characters long.
78 static char tmpf[23] = "TMP";
80 /* Generate random bytes. This uses a boring repeatable algorithm and it
81 * is implemented here so that it gives the same set of numbers on every
82 * architecture. It's a linear congruential generator (Knuth or Sedgewick
83 * "Algorithms") but it comes from the 'feedback taps' table in Horowitz and
84 * Hill, "The Art of Electronics".
87 make_random_bytes(png_uint_32* seed, void* pv, size_t size)
89 png_uint_32 u0 = seed[0], u1 = seed[1];
90 png_bytep bytes = voidcast(png_bytep, pv);
92 /* There are thirty three bits, the next bit in the sequence is bit-33 XOR
93 * bit-20. The top 1 bit is in u1, the bottom 32 are in u0.
96 for (i=0; i<size; ++i)
98 /* First generate 8 new bits then shift them in at the end. */
99 png_uint_32 u = ((u0 >> (20-8)) ^ ((u1 << 7) | (u0 >> (32-7)))) & 0xff;
104 *bytes++ = (png_byte)u;
111 static png_uint_32 color_seed[2];
116 color_seed[0] = 0x12345678U;
117 color_seed[1] = 0x9abcdefU;
121 random_color(png_colorp color)
123 make_random_bytes(color_seed, color, sizeof *color);
126 /* Math support - neither Cygwin nor Visual Studio have C99 support and we need
127 * a predictable rounding function, so make one here:
130 closestinteger(double x)
132 return floor(x + .5);
135 /* Cast support: remove GCC whines. */
139 d = closestinteger(d);
146 d = closestinteger(d);
147 return (png_uint_16)d;
150 /* sRGB support: use exact calculations rounded to the nearest int, see the
151 * fesetround() call in main(). sRGB_to_d optimizes the 8 to 16-bit conversion.
153 static double sRGB_to_d[256];
154 static double g22_to_d[256];
162 for (i=1; i<255; ++i)
163 sRGB_to_d[i] = linear_from_sRGB(i/255.);
167 for (i=1; i<255; ++i)
168 g22_to_d[i] = pow(i/255., 1/.45455);
173 sRGB(double linear /*range 0.0 .. 1.0*/)
175 return u8d(255 * sRGB_from_linear(linear));
179 isRGB(int fixed_linear)
181 return sRGB(fixed_linear / 65535.);
186 unpremultiply(int component, int alpha)
188 if (alpha <= component)
189 return 255; /* Arbitrary, but consistent with the libpng code */
191 else if (alpha >= 65535)
192 return isRGB(component);
195 return sRGB((double)component / alpha);
200 ilinear(int fixed_srgb)
202 return u16d(65535 * sRGB_to_d[fixed_srgb]);
206 ilineara(int fixed_srgb, int alpha)
208 return u16d((257 * alpha) * sRGB_to_d[fixed_srgb]);
212 ilinear_g22(int fixed_srgb)
214 return u16d(65535 * g22_to_d[fixed_srgb]);
219 ilineara_g22(int fixed_srgb, int alpha)
221 return u16d((257 * alpha) * g22_to_d[fixed_srgb]);
226 YfromRGBint(int ir, int ig, int ib)
231 return YfromRGB(r, g, b);
235 /* The error that results from using a 2.2 power law in place of the correct
236 * sRGB transform, given an 8-bit value which might be either sRGB or power-law.
239 power_law_error8(int value)
241 if (value > 0 && value < 255)
243 double vd = value / 255.;
245 pow(sRGB_to_d[value], 1/2.2) - sRGB_from_linear(pow(vd, 2.2)));
247 /* Always allow an extra 1 here for rounding errors */
248 e = 1+floor(255 * e);
255 static int error_in_sRGB_roundtrip = 56; /* by experiment */
257 power_law_error16(int value)
259 if (value > 0 && value < 65535)
261 /* Round trip the value through an 8-bit representation but using
262 * non-matching to/from conversions.
264 double vd = value / 65535.;
266 pow(sRGB_from_linear(vd), 2.2) - linear_from_sRGB(pow(vd, 1/2.2)));
268 /* Always allow an extra 1 here for rounding errors */
269 e = error_in_sRGB_roundtrip+floor(65535 * e);
277 compare_8bit(int v1, int v2, int error_limit, int multiple_algorithms)
282 if (e <= error_limit)
285 if (!multiple_algorithms)
288 ev1 = power_law_error8(v1);
292 ev2 = power_law_error8(v2);
300 compare_16bit(int v1, int v2, int error_limit, int multiple_algorithms)
305 if (e <= error_limit)
308 /* "multiple_algorithms" in this case means that a color-map has been
309 * involved somewhere, so we can deduce that the values were forced to 8-bit
310 * (like the via_linear case for 8-bit.)
312 if (!multiple_algorithms)
315 ev1 = power_law_error16(v1);
319 ev2 = power_law_error16(v2);
327 #define USE_FILE 1 /* else memory */
328 #define USE_STDIO 2 /* else use file name */
329 #define STRICT 4 /* fail on warnings too */
331 #define KEEP_TMPFILES 16 /* else delete temporary files */
332 #define KEEP_GOING 32
333 #define ACCUMULATE 64
334 #define FAST_WRITE 128
335 #define sRGB_16BIT 256
336 #define NO_RESEED 512 /* do not reseed on each new file */
337 #define GBG_ERROR 1024 /* do not ignore the gamma+background_rgb_to_gray
341 print_opts(png_uint_32 opts)
345 if (opts & USE_STDIO)
347 if (!(opts & STRICT))
348 printf(" --nostrict");
350 printf(" --verbose");
351 if (opts & KEEP_TMPFILES)
352 printf(" --preserve");
353 if (opts & KEEP_GOING)
354 printf(" --keep-going");
355 if (opts & ACCUMULATE)
356 printf(" --accumulate");
357 if (!(opts & FAST_WRITE)) /* --fast is currently the default */
359 if (opts & sRGB_16BIT)
360 printf(" --sRGB-16bit");
361 if (opts & NO_RESEED)
362 printf(" --noreseed");
363 #if PNG_LIBPNG_VER < 10700 /* else on by default */
364 if (opts & GBG_ERROR)
365 printf(" --fault-gbg-warning");
369 #define FORMAT_NO_CHANGE 0x80000000 /* additional flag */
371 /* A name table for all the formats - defines the format of the '+' arguments to
374 #define FORMAT_COUNT 64
375 #define FORMAT_MASK 0x3f
376 static const char * const format_names[FORMAT_COUNT] =
387 "color-mapped-sRGB-gray",
388 "color-mapped-sRGB-gray+alpha",
389 "color-mapped-sRGB-rgb",
390 "color-mapped-sRGB-rgb+alpha",
391 "color-mapped-linear-gray",
392 "color-mapped-linear-gray+alpha",
393 "color-mapped-linear-rgb",
394 "color-mapped-linear-rgb+alpha",
405 "color-mapped-sRGB-gray",
406 "color-mapped-sRGB-gray+alpha",
407 "color-mapped-sRGB-bgr",
408 "color-mapped-sRGB-bgr+alpha",
409 "color-mapped-linear-gray",
410 "color-mapped-linear-gray+alpha",
411 "color-mapped-linear-bgr",
412 "color-mapped-linear-bgr+alpha",
423 "color-mapped-sRGB-gray",
424 "color-mapped-alpha+sRGB-gray",
425 "color-mapped-sRGB-rgb",
426 "color-mapped-alpha+sRGB-rgb",
427 "color-mapped-linear-gray",
428 "color-mapped-alpha+linear-gray",
429 "color-mapped-linear-rgb",
430 "color-mapped-alpha+linear-rgb",
441 "color-mapped-sRGB-gray",
442 "color-mapped-alpha+sRGB-gray",
443 "color-mapped-sRGB-bgr",
444 "color-mapped-alpha+sRGB-bgr",
445 "color-mapped-linear-gray",
446 "color-mapped-alpha+linear-gray",
447 "color-mapped-linear-bgr",
448 "color-mapped-alpha+linear-bgr",
451 /* Decode an argument to a format number. */
453 formatof(const char *arg)
456 unsigned long format = strtoul(arg, &ep, 0);
458 if (ep > arg && *ep == 0 && format < FORMAT_COUNT)
459 return (png_uint_32)format;
461 else for (format=0; format < FORMAT_COUNT; ++format)
463 if (strcmp(format_names[format], arg) == 0)
464 return (png_uint_32)format;
467 fprintf(stderr, "pngstest: format name '%s' invalid\n", arg);
471 /* Bitset/test functions for formats */
472 #define FORMAT_SET_COUNT (FORMAT_COUNT / 32)
475 png_uint_32 bits[FORMAT_SET_COUNT];
479 static void format_init(format_list *pf)
482 for (i=0; i<FORMAT_SET_COUNT; ++i)
483 pf->bits[i] = 0; /* All off */
486 #if 0 /* currently unused */
487 static void format_clear(format_list *pf)
490 for (i=0; i<FORMAT_SET_COUNT; ++i)
495 static int format_is_initial(format_list *pf)
498 for (i=0; i<FORMAT_SET_COUNT; ++i)
499 if (pf->bits[i] != 0)
505 static int format_set(format_list *pf, png_uint_32 format)
507 if (format < FORMAT_COUNT)
508 return pf->bits[format >> 5] |= ((png_uint_32)1) << (format & 31);
513 #if 0 /* currently unused */
514 static int format_unset(format_list *pf, png_uint_32 format)
516 if (format < FORMAT_COUNT)
517 return pf->bits[format >> 5] &= ~((png_uint_32)1) << (format & 31);
523 static int format_isset(format_list *pf, png_uint_32 format)
525 return format < FORMAT_COUNT &&
526 (pf->bits[format >> 5] & (((png_uint_32)1) << (format & 31))) != 0;
529 static void format_default(format_list *pf, int redundant)
535 /* set everything, including flags that are pointless */
536 for (i=0; i<FORMAT_SET_COUNT; ++i)
537 pf->bits[i] = ~(png_uint_32)0;
544 for (f=0; f<FORMAT_COUNT; ++f)
546 /* Eliminate redundant and unsupported settings. */
547 # ifdef PNG_FORMAT_BGR_SUPPORTED
548 /* BGR is meaningless if no color: */
549 if ((f & PNG_FORMAT_FLAG_COLOR) == 0 &&
550 (f & PNG_FORMAT_FLAG_BGR) != 0)
552 if ((f & 0x10U/*HACK: fixed value*/) != 0)
556 /* AFIRST is meaningless if no alpha: */
557 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
558 if ((f & PNG_FORMAT_FLAG_ALPHA) == 0 &&
559 (f & PNG_FORMAT_FLAG_AFIRST) != 0)
561 if ((f & 0x20U/*HACK: fixed value*/) != 0)
570 /* THE Image STRUCTURE */
571 /* The super-class of a png_image, contains the decoded image plus the input
572 * data necessary to re-read the file with a different format.
578 const char *file_name;
581 png_voidp input_memory;
582 size_t input_memory_size;
587 char tmpfile_name[32];
588 png_uint_16 colormap[256*4];
592 /* Initializer: also sets the permitted error limit for 16-bit operations. */
594 newimage(Image *image)
596 memset(image, 0, sizeof *image);
599 /* Reset the image to be read again - only needs to rewind the FILE* at present.
602 resetimage(Image *image)
604 if (image->input_file != NULL)
605 rewind(image->input_file);
608 /* Free the image buffer; the buffer is re-used on a re-read, this is just for
612 freebuffer(Image *image)
614 if (image->buffer) free(image->buffer);
615 image->buffer = NULL;
617 image->allocsize = 0;
620 /* Delete function; cleans out all the allocated data and the temporary file in
624 freeimage(Image *image)
627 png_image_free(&image->image);
629 if (image->input_file != NULL)
631 fclose(image->input_file);
632 image->input_file = NULL;
635 if (image->input_memory != NULL)
637 free(image->input_memory);
638 image->input_memory = NULL;
639 image->input_memory_size = 0;
642 if (image->tmpfile_name[0] != 0 && (image->opts & KEEP_TMPFILES) == 0)
644 (void)remove(image->tmpfile_name);
645 image->tmpfile_name[0] = 0;
649 /* This is actually a re-initializer; allows an image structure to be re-used by
650 * freeing everything that relates to an old image.
652 static void initimage(Image *image, png_uint_32 opts, const char *file_name,
656 memset(&image->image, 0, sizeof image->image);
658 image->file_name = file_name;
659 image->stride_extra = stride_extra;
662 /* Make sure the image buffer is big enough; allows re-use of the buffer if the
665 #define BUFFER_INIT8 73
667 allocbuffer(Image *image)
669 size_t size = PNG_IMAGE_BUFFER_SIZE(image->image, image->stride);
671 if (size+32 > image->bufsize)
674 image->buffer = voidcast(png_bytep, malloc(size+32));
675 if (image->buffer == NULL)
679 "simpletest: out of memory allocating %lu(+32) byte buffer\n",
680 (unsigned long)size);
683 image->bufsize = size+32;
686 memset(image->buffer, 95, image->bufsize);
687 memset(image->buffer+16, BUFFER_INIT8, size);
688 image->allocsize = size;
691 /* Make sure 16 bytes match the given byte. */
693 check16(png_const_bytep bp, int b)
698 if (*bp != b) return 1;
704 /* Check for overwrite in the image buffer. */
706 checkbuffer(Image *image, const char *arg)
708 if (check16(image->buffer, 95))
711 fprintf(stderr, "%s: overwrite at start of image buffer\n", arg);
715 if (check16(image->buffer+16+image->allocsize, 95))
718 fprintf(stderr, "%s: overwrite at end of image buffer\n", arg);
724 /* Log a terminal error, also frees the libpng part of the image if necessary.
727 logerror(Image *image, const char *a1, const char *a2, const char *a3)
730 if (image->image.warning_or_error)
731 fprintf(stderr, "%s%s%s: %s\n", a1, a2, a3, image->image.message);
734 fprintf(stderr, "%s%s%s\n", a1, a2, a3);
736 if (image->image.opaque != NULL)
738 fprintf(stderr, "%s: image opaque pointer non-NULL on error\n",
740 png_image_free(&image->image);
746 /* Log an error and close a file (just a utility to do both things in one
750 logclose(Image *image, FILE *f, const char *name, const char *operation)
755 return logerror(image, name, operation, strerror(e));
758 /* Make sure the png_image has been freed - validates that libpng is doing what
759 * the spec says and freeing the image.
762 checkopaque(Image *image)
764 if (image->image.opaque != NULL)
766 png_image_free(&image->image);
767 return logerror(image, image->file_name, ": opaque not NULL", "");
770 /* Separate out the gamma+background_rgb_to_gray warning because it may
771 * produce opaque component errors:
773 else if (image->image.warning_or_error != 0 &&
774 (strcmp(image->image.message,
775 "libpng does not support gamma+background+rgb_to_gray") == 0 ?
776 (image->opts & GBG_ERROR) != 0 : (image->opts & STRICT) != 0))
777 return logerror(image, image->file_name, (image->opts & GBG_ERROR) != 0 ?
778 " --fault-gbg-warning" : " --strict", "");
784 /* IMAGE COMPARISON/CHECKING */
785 /* Compare the pixels of two images, which should be the same but aren't. The
786 * images must have been checked for a size match.
790 /* The components, for grayscale images the gray value is in 'g' and if alpha
791 * is not present 'a' is set to 255 or 65535 according to format.
798 /* The background as the original sRGB 8-bit value converted to the final
799 * integer format and as a double precision linear value in the range 0..1
800 * for with partially transparent pixels.
803 double dr, dg, db; /* linear r,g,b scaled to 0..1 */
806 /* Basic image formats; control the data but not the layout thereof. */
807 #define BASE_FORMATS\
808 (PNG_FORMAT_FLAG_ALPHA|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_LINEAR)
810 /* Read a Pixel from a buffer. The code below stores the correct routine for
811 * the format in a function pointer, these are the routines:
814 gp_g8(Pixel *p, png_const_voidp pb)
816 png_const_bytep pp = voidcast(png_const_bytep, pb);
818 p->r = p->g = p->b = pp[0];
823 gp_ga8(Pixel *p, png_const_voidp pb)
825 png_const_bytep pp = voidcast(png_const_bytep, pb);
827 p->r = p->g = p->b = pp[0];
831 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
833 gp_ag8(Pixel *p, png_const_voidp pb)
835 png_const_bytep pp = voidcast(png_const_bytep, pb);
837 p->r = p->g = p->b = pp[1];
843 gp_rgb8(Pixel *p, png_const_voidp pb)
845 png_const_bytep pp = voidcast(png_const_bytep, pb);
853 #ifdef PNG_FORMAT_BGR_SUPPORTED
855 gp_bgr8(Pixel *p, png_const_voidp pb)
857 png_const_bytep pp = voidcast(png_const_bytep, pb);
867 gp_rgba8(Pixel *p, png_const_voidp pb)
869 png_const_bytep pp = voidcast(png_const_bytep, pb);
877 #ifdef PNG_FORMAT_BGR_SUPPORTED
879 gp_bgra8(Pixel *p, png_const_voidp pb)
881 png_const_bytep pp = voidcast(png_const_bytep, pb);
890 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
892 gp_argb8(Pixel *p, png_const_voidp pb)
894 png_const_bytep pp = voidcast(png_const_bytep, pb);
903 #if defined(PNG_FORMAT_AFIRST_SUPPORTED) && defined(PNG_FORMAT_BGR_SUPPORTED)
905 gp_abgr8(Pixel *p, png_const_voidp pb)
907 png_const_bytep pp = voidcast(png_const_bytep, pb);
917 gp_g16(Pixel *p, png_const_voidp pb)
919 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
921 p->r = p->g = p->b = pp[0];
926 gp_ga16(Pixel *p, png_const_voidp pb)
928 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
930 p->r = p->g = p->b = pp[0];
934 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
936 gp_ag16(Pixel *p, png_const_voidp pb)
938 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
940 p->r = p->g = p->b = pp[1];
946 gp_rgb16(Pixel *p, png_const_voidp pb)
948 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
956 #ifdef PNG_FORMAT_BGR_SUPPORTED
958 gp_bgr16(Pixel *p, png_const_voidp pb)
960 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
970 gp_rgba16(Pixel *p, png_const_voidp pb)
972 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
980 #ifdef PNG_FORMAT_BGR_SUPPORTED
982 gp_bgra16(Pixel *p, png_const_voidp pb)
984 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
993 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
995 gp_argb16(Pixel *p, png_const_voidp pb)
997 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
1006 #if defined(PNG_FORMAT_AFIRST_SUPPORTED) && defined(PNG_FORMAT_BGR_SUPPORTED)
1008 gp_abgr16(Pixel *p, png_const_voidp pb)
1010 png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
1019 /* Given a format, return the correct one of the above functions. */
1021 get_pixel(png_uint_32 format))(Pixel *p, png_const_voidp pb)
1023 /* The color-map flag is irrelevant here - the caller of the function
1024 * returned must either pass the buffer or, for a color-mapped image, the
1025 * correct entry in the color-map.
1027 if (format & PNG_FORMAT_FLAG_LINEAR)
1029 if (format & PNG_FORMAT_FLAG_COLOR)
1031 # ifdef PNG_FORMAT_BGR_SUPPORTED
1032 if (format & PNG_FORMAT_FLAG_BGR)
1034 if (format & PNG_FORMAT_FLAG_ALPHA)
1036 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1037 if (format & PNG_FORMAT_FLAG_AFIRST)
1052 if (format & PNG_FORMAT_FLAG_ALPHA)
1054 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1055 if (format & PNG_FORMAT_FLAG_AFIRST)
1070 if (format & PNG_FORMAT_FLAG_ALPHA)
1072 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1073 if (format & PNG_FORMAT_FLAG_AFIRST)
1088 if (format & PNG_FORMAT_FLAG_COLOR)
1090 # ifdef PNG_FORMAT_BGR_SUPPORTED
1091 if (format & PNG_FORMAT_FLAG_BGR)
1093 if (format & PNG_FORMAT_FLAG_ALPHA)
1095 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1096 if (format & PNG_FORMAT_FLAG_AFIRST)
1111 if (format & PNG_FORMAT_FLAG_ALPHA)
1113 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1114 if (format & PNG_FORMAT_FLAG_AFIRST)
1129 if (format & PNG_FORMAT_FLAG_ALPHA)
1131 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1132 if (format & PNG_FORMAT_FLAG_AFIRST)
1146 /* Conversion between pixel formats. The code above effectively eliminates the
1147 * component ordering changes leaving three basic changes:
1149 * 1) Remove an alpha channel by pre-multiplication or compositing on a
1150 * background color. (Adding an alpha channel is a no-op.)
1152 * 2) Remove color by mapping to grayscale. (Grayscale to color is a no-op.)
1154 * 3) Convert between 8-bit and 16-bit components. (Both directtions are
1157 * This gives the following base format conversion matrix:
1159 * OUT: ----- 8-bit ----- ----- 16-bit -----
1160 * IN G GA RGB RGBA G GA RGB RGBA
1161 * 8 G . . . . lin lin lin lin
1162 * 8 GA bckg . bckc . pre' pre pre' pre
1163 * 8 RGB g8 g8 . . glin glin lin lin
1164 * 8 RGBA g8b g8 bckc . gpr' gpre pre' pre
1165 * 16 G sRGB sRGB sRGB sRGB . . . .
1166 * 16 GA b16g unpg b16c unpc A . A .
1167 * 16 RGB sG sG sRGB sRGB g16 g16 . .
1168 * 16 RGBA gb16 sGp cb16 sCp g16 g16' A .
1171 * bckg: composite on gray background
1172 * bckc: composite on color background
1173 * g8: convert sRGB components to sRGB grayscale
1174 * g8b: convert sRGB components to grayscale and composite on gray background
1177 * lin: make sRGB components linear, alpha := 65535
1178 * pre: make sRGB components linear and premultiply by alpha (scale alpha)
1179 * pre': as 'pre' but alpha := 65535
1180 * glin: make sRGB components linear, convert to grayscale, alpha := 65535
1181 * gpre: make sRGB components grayscale and linear and premultiply by alpha
1182 * gpr': as 'gpre' but alpha := 65535
1185 * sRGB: convert linear components to sRGB, alpha := 255
1186 * unpg: unpremultiply gray component and convert to sRGB (scale alpha)
1187 * unpc: unpremultiply color components and convert to sRGB (scale alpha)
1188 * b16g: composite linear onto gray background and convert the result to sRGB
1189 * b16c: composite linear onto color background and convert the result to sRGB
1190 * sG: convert linear RGB to sRGB grayscale
1191 * sGp: unpremultiply RGB then convert to sRGB grayscale
1192 * sCp: unpremultiply RGB then convert to sRGB
1193 * gb16: composite linear onto background and convert to sRGB grayscale
1194 * (order doesn't matter, the composite and grayscale operations permute)
1195 * cb16: composite linear onto background and convert to sRGB
1198 * A: set alpha to 65535
1199 * g16: convert linear RGB to linear grayscale (alpha := 65535)
1200 * g16': as 'g16' but alpha is unchanged
1204 gpc_noop(Pixel *out, const Pixel *in, const Background *back)
1213 #if ALLOW_UNUSED_GPC
1215 gpc_nop8(Pixel *out, const Pixel *in, const Background *back)
1219 out->r = out->g = out->b = 255;
1232 #if ALLOW_UNUSED_GPC
1234 gpc_nop6(Pixel *out, const Pixel *in, const Background *back)
1238 out->r = out->g = out->b = 65535;
1251 /* 8-bit to 8-bit conversions */
1252 /* bckg: composite on gray background */
1254 gpc_bckg(Pixel *out, const Pixel *in, const Background *back)
1257 out->r = out->g = out->b = back->ig;
1259 else if (in->a >= 255)
1260 out->r = out->g = out->b = in->g;
1264 double a = in->a / 255.;
1266 out->r = out->g = out->b = sRGB(sRGB_to_d[in->g] * a + back->dg * (1-a));
1272 /* bckc: composite on color background */
1274 gpc_bckc(Pixel *out, const Pixel *in, const Background *back)
1283 else if (in->a >= 255)
1292 double a = in->a / 255.;
1294 out->r = sRGB(sRGB_to_d[in->r] * a + back->dr * (1-a));
1295 out->g = sRGB(sRGB_to_d[in->g] * a + back->dg * (1-a));
1296 out->b = sRGB(sRGB_to_d[in->b] * a + back->db * (1-a));
1302 /* g8: convert sRGB components to sRGB grayscale */
1304 gpc_g8(Pixel *out, const Pixel *in, const Background *back)
1308 if (in->r == in->g && in->g == in->b)
1309 out->r = out->g = out->b = in->g;
1312 out->r = out->g = out->b =
1313 sRGB(YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
1318 /* g8b: convert sRGB components to grayscale and composite on gray background */
1320 gpc_g8b(Pixel *out, const Pixel *in, const Background *back)
1323 out->r = out->g = out->b = back->ig;
1325 else if (in->a >= 255)
1327 if (in->r == in->g && in->g == in->b)
1328 out->r = out->g = out->b = in->g;
1331 out->r = out->g = out->b = sRGB(YfromRGB(
1332 sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
1337 double a = in->a/255.;
1339 out->r = out->g = out->b = sRGB(a * YfromRGB(sRGB_to_d[in->r],
1340 sRGB_to_d[in->g], sRGB_to_d[in->b]) + back->dg * (1-a));
1346 /* 8-bit to 16-bit conversions */
1347 /* lin: make sRGB components linear, alpha := 65535 */
1349 gpc_lin(Pixel *out, const Pixel *in, const Background *back)
1353 out->r = ilinear(in->r);
1363 out->b = ilinear(in->b);
1368 out->g = ilinear(in->g);
1373 else if (in->b == in->g)
1377 out->b = ilinear(in->b);
1383 /* pre: make sRGB components linear and premultiply by alpha (scale alpha) */
1385 gpc_pre(Pixel *out, const Pixel *in, const Background *back)
1389 out->r = ilineara(in->r, in->a);
1399 out->b = ilineara(in->b, in->a);
1404 out->g = ilineara(in->g, in->a);
1409 else if (in->b == in->g)
1413 out->b = ilineara(in->b, in->a);
1416 out->a = in->a * 257;
1419 /* pre': as 'pre' but alpha := 65535 */
1421 gpc_preq(Pixel *out, const Pixel *in, const Background *back)
1425 out->r = ilineara(in->r, in->a);
1435 out->b = ilineara(in->b, in->a);
1440 out->g = ilineara(in->g, in->a);
1445 else if (in->b == in->g)
1449 out->b = ilineara(in->b, in->a);
1455 /* glin: make sRGB components linear, convert to grayscale, alpha := 65535 */
1457 gpc_glin(Pixel *out, const Pixel *in, const Background *back)
1461 if (in->r == in->g && in->g == in->b)
1462 out->r = out->g = out->b = ilinear(in->g);
1465 out->r = out->g = out->b = u16d(65535 *
1466 YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
1471 /* gpre: make sRGB components grayscale and linear and premultiply by alpha */
1473 gpc_gpre(Pixel *out, const Pixel *in, const Background *back)
1477 if (in->r == in->g && in->g == in->b)
1478 out->r = out->g = out->b = ilineara(in->g, in->a);
1481 out->r = out->g = out->b = u16d(in->a * 257 *
1482 YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
1484 out->a = 257 * in->a;
1487 /* gpr': as 'gpre' but alpha := 65535 */
1489 gpc_gprq(Pixel *out, const Pixel *in, const Background *back)
1493 if (in->r == in->g && in->g == in->b)
1494 out->r = out->g = out->b = ilineara(in->g, in->a);
1497 out->r = out->g = out->b = u16d(in->a * 257 *
1498 YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
1503 /* 8-bit to 16-bit conversions for gAMA 45455 encoded values */
1504 /* Lin: make gAMA 45455 components linear, alpha := 65535 */
1506 gpc_Lin(Pixel *out, const Pixel *in, const Background *back)
1510 out->r = ilinear_g22(in->r);
1520 out->b = ilinear_g22(in->b);
1525 out->g = ilinear_g22(in->g);
1530 else if (in->b == in->g)
1534 out->b = ilinear_g22(in->b);
1540 #if ALLOW_UNUSED_GPC
1541 /* Pre: make gAMA 45455 components linear and premultiply by alpha (scale alpha)
1544 gpc_Pre(Pixel *out, const Pixel *in, const Background *back)
1548 out->r = ilineara_g22(in->r, in->a);
1558 out->b = ilineara_g22(in->b, in->a);
1563 out->g = ilineara_g22(in->g, in->a);
1568 else if (in->b == in->g)
1572 out->b = ilineara_g22(in->b, in->a);
1575 out->a = in->a * 257;
1579 #if ALLOW_UNUSED_GPC
1580 /* Pre': as 'Pre' but alpha := 65535 */
1582 gpc_Preq(Pixel *out, const Pixel *in, const Background *back)
1586 out->r = ilineara_g22(in->r, in->a);
1596 out->b = ilineara_g22(in->b, in->a);
1601 out->g = ilineara_g22(in->g, in->a);
1606 else if (in->b == in->g)
1610 out->b = ilineara_g22(in->b, in->a);
1617 #if ALLOW_UNUSED_GPC
1618 /* Glin: make gAMA 45455 components linear, convert to grayscale, alpha := 65535
1621 gpc_Glin(Pixel *out, const Pixel *in, const Background *back)
1625 if (in->r == in->g && in->g == in->b)
1626 out->r = out->g = out->b = ilinear_g22(in->g);
1629 out->r = out->g = out->b = u16d(65535 *
1630 YfromRGB(g22_to_d[in->r], g22_to_d[in->g], g22_to_d[in->b]));
1636 #if ALLOW_UNUSED_GPC
1637 /* Gpre: make gAMA 45455 components grayscale and linear and premultiply by
1641 gpc_Gpre(Pixel *out, const Pixel *in, const Background *back)
1645 if (in->r == in->g && in->g == in->b)
1646 out->r = out->g = out->b = ilineara_g22(in->g, in->a);
1649 out->r = out->g = out->b = u16d(in->a * 257 *
1650 YfromRGB(g22_to_d[in->r], g22_to_d[in->g], g22_to_d[in->b]));
1652 out->a = 257 * in->a;
1656 #if ALLOW_UNUSED_GPC
1657 /* Gpr': as 'Gpre' but alpha := 65535 */
1659 gpc_Gprq(Pixel *out, const Pixel *in, const Background *back)
1663 if (in->r == in->g && in->g == in->b)
1664 out->r = out->g = out->b = ilineara_g22(in->g, in->a);
1667 out->r = out->g = out->b = u16d(in->a * 257 *
1668 YfromRGB(g22_to_d[in->r], g22_to_d[in->g], g22_to_d[in->b]));
1674 /* 16-bit to 8-bit conversions */
1675 /* sRGB: convert linear components to sRGB, alpha := 255 */
1677 gpc_sRGB(Pixel *out, const Pixel *in, const Background *back)
1681 out->r = isRGB(in->r);
1691 out->b = isRGB(in->b);
1696 out->g = isRGB(in->g);
1701 else if (in->b == in->g)
1705 out->b = isRGB(in->b);
1711 /* unpg: unpremultiply gray component and convert to sRGB (scale alpha) */
1713 gpc_unpg(Pixel *out, const Pixel *in, const Background *back)
1719 out->r = out->g = out->b = 255;
1725 out->r = out->g = out->b = sRGB((double)in->g / in->a);
1726 out->a = u8d(in->a / 257.);
1730 /* unpc: unpremultiply color components and convert to sRGB (scale alpha) */
1732 gpc_unpc(Pixel *out, const Pixel *in, const Background *back)
1738 out->r = out->g = out->b = 255;
1744 out->r = sRGB((double)in->r / in->a);
1745 out->g = sRGB((double)in->g / in->a);
1746 out->b = sRGB((double)in->b / in->a);
1747 out->a = u8d(in->a / 257.);
1751 /* b16g: composite linear onto gray background and convert the result to sRGB */
1753 gpc_b16g(Pixel *out, const Pixel *in, const Background *back)
1756 out->r = out->g = out->b = back->ig;
1760 double a = in->a/65535.;
1764 out->r = out->g = out->b = sRGB(in->g * a + back->dg * a1);
1770 /* b16c: composite linear onto color background and convert the result to sRGB*/
1772 gpc_b16c(Pixel *out, const Pixel *in, const Background *back)
1783 double a = in->a/65535.;
1787 out->r = sRGB(in->r * a + back->dr * a1);
1788 out->g = sRGB(in->g * a + back->dg * a1);
1789 out->b = sRGB(in->b * a + back->db * a1);
1795 /* sG: convert linear RGB to sRGB grayscale */
1797 gpc_sG(Pixel *out, const Pixel *in, const Background *back)
1801 out->r = out->g = out->b = sRGB(YfromRGBint(in->r, in->g, in->b)/65535);
1805 /* sGp: unpremultiply RGB then convert to sRGB grayscale */
1807 gpc_sGp(Pixel *out, const Pixel *in, const Background *back)
1813 out->r = out->g = out->b = 255;
1819 out->r = out->g = out->b = sRGB(YfromRGBint(in->r, in->g, in->b)/in->a);
1820 out->a = u8d(in->a / 257.);
1824 /* sCp: unpremultiply RGB then convert to sRGB */
1826 gpc_sCp(Pixel *out, const Pixel *in, const Background *back)
1832 out->r = out->g = out->b = 255;
1838 out->r = sRGB((double)in->r / in->a);
1839 out->g = sRGB((double)in->g / in->a);
1840 out->b = sRGB((double)in->b / in->a);
1841 out->a = u8d(in->a / 257.);
1845 /* gb16: composite linear onto background and convert to sRGB grayscale */
1846 /* (order doesn't matter, the composite and grayscale operations permute) */
1848 gpc_gb16(Pixel *out, const Pixel *in, const Background *back)
1851 out->r = out->g = out->b = back->ig;
1853 else if (in->a >= 65535)
1854 out->r = out->g = out->b = isRGB(in->g);
1858 double a = in->a / 65535.;
1862 out->r = out->g = out->b = sRGB(in->g * a + back->dg * a1);
1868 /* cb16: composite linear onto background and convert to sRGB */
1870 gpc_cb16(Pixel *out, const Pixel *in, const Background *back)
1879 else if (in->a >= 65535)
1881 out->r = isRGB(in->r);
1882 out->g = isRGB(in->g);
1883 out->b = isRGB(in->b);
1888 double a = in->a / 65535.;
1892 out->r = sRGB(in->r * a + back->dr * a1);
1893 out->g = sRGB(in->g * a + back->dg * a1);
1894 out->b = sRGB(in->b * a + back->db * a1);
1900 /* 16-bit to 16-bit conversions */
1901 /* A: set alpha to 65535 */
1903 gpc_A(Pixel *out, const Pixel *in, const Background *back)
1912 /* g16: convert linear RGB to linear grayscale (alpha := 65535) */
1914 gpc_g16(Pixel *out, const Pixel *in, const Background *back)
1917 out->r = out->g = out->b = u16d(YfromRGBint(in->r, in->g, in->b));
1921 /* g16': as 'g16' but alpha is unchanged */
1923 gpc_g16q(Pixel *out, const Pixel *in, const Background *back)
1926 out->r = out->g = out->b = u16d(YfromRGBint(in->r, in->g, in->b));
1930 #if ALLOW_UNUSED_GPC
1931 /* Unused functions (to hide them from GCC unused function warnings) */
1932 void (* const gpc_unused[])
1933 (Pixel *out, const Pixel *in, const Background *back) =
1935 gpc_Pre, gpc_Preq, gpc_Glin, gpc_Gpre, gpc_Gprq, gpc_nop8, gpc_nop6
1939 /* OUT: ----- 8-bit ----- ----- 16-bit -----
1940 * IN G GA RGB RGBA G GA RGB RGBA
1941 * 8 G . . . . lin lin lin lin
1942 * 8 GA bckg . bckc . pre' pre pre' pre
1943 * 8 RGB g8 g8 . . glin glin lin lin
1944 * 8 RGBA g8b g8 bckc . gpr' gpre pre' pre
1945 * 16 G sRGB sRGB sRGB sRGB . . . .
1946 * 16 GA b16g unpg b16c unpc A . A .
1947 * 16 RGB sG sG sRGB sRGB g16 g16 . .
1948 * 16 RGBA gb16 sGp cb16 sCp g16 g16' A .
1950 * The matrix is held in an array indexed thus:
1952 * gpc_fn[out_format & BASE_FORMATS][in_format & BASE_FORMATS];
1954 /* This will produce a compile time error if the FORMAT_FLAG values don't
1955 * match the above matrix!
1957 #if PNG_FORMAT_FLAG_ALPHA == 1 && PNG_FORMAT_FLAG_COLOR == 2 &&\
1958 PNG_FORMAT_FLAG_LINEAR == 4
1959 static void (* const gpc_fn[8/*in*/][8/*out*/])
1960 (Pixel *out, const Pixel *in, const Background *back) =
1962 /*out: G-8 GA-8 RGB-8 RGBA-8 G-16 GA-16 RGB-16 RGBA-16 */
1963 {gpc_noop,gpc_noop,gpc_noop,gpc_noop, gpc_Lin, gpc_Lin, gpc_Lin, gpc_Lin },
1964 {gpc_bckg,gpc_noop,gpc_bckc,gpc_noop, gpc_preq,gpc_pre, gpc_preq,gpc_pre },
1965 {gpc_g8, gpc_g8, gpc_noop,gpc_noop, gpc_glin,gpc_glin,gpc_lin, gpc_lin },
1966 {gpc_g8b, gpc_g8, gpc_bckc,gpc_noop, gpc_gprq,gpc_gpre,gpc_preq,gpc_pre },
1967 {gpc_sRGB,gpc_sRGB,gpc_sRGB,gpc_sRGB, gpc_noop,gpc_noop,gpc_noop,gpc_noop},
1968 {gpc_b16g,gpc_unpg,gpc_b16c,gpc_unpc, gpc_A, gpc_noop,gpc_A, gpc_noop},
1969 {gpc_sG, gpc_sG, gpc_sRGB,gpc_sRGB, gpc_g16, gpc_g16, gpc_noop,gpc_noop},
1970 {gpc_gb16,gpc_sGp, gpc_cb16,gpc_sCp, gpc_g16, gpc_g16q,gpc_A, gpc_noop}
1973 /* The array is repeated for the cases where both the input and output are color
1974 * mapped because then different algorithms are used.
1976 static void (* const gpc_fn_colormapped[8/*in*/][8/*out*/])
1977 (Pixel *out, const Pixel *in, const Background *back) =
1979 /*out: G-8 GA-8 RGB-8 RGBA-8 G-16 GA-16 RGB-16 RGBA-16 */
1980 {gpc_noop,gpc_noop,gpc_noop,gpc_noop, gpc_lin, gpc_lin, gpc_lin, gpc_lin },
1981 {gpc_bckg,gpc_noop,gpc_bckc,gpc_noop, gpc_preq,gpc_pre, gpc_preq,gpc_pre },
1982 {gpc_g8, gpc_g8, gpc_noop,gpc_noop, gpc_glin,gpc_glin,gpc_lin, gpc_lin },
1983 {gpc_g8b, gpc_g8, gpc_bckc,gpc_noop, gpc_gprq,gpc_gpre,gpc_preq,gpc_pre },
1984 {gpc_sRGB,gpc_sRGB,gpc_sRGB,gpc_sRGB, gpc_noop,gpc_noop,gpc_noop,gpc_noop},
1985 {gpc_b16g,gpc_unpg,gpc_b16c,gpc_unpc, gpc_A, gpc_noop,gpc_A, gpc_noop},
1986 {gpc_sG, gpc_sG, gpc_sRGB,gpc_sRGB, gpc_g16, gpc_g16, gpc_noop,gpc_noop},
1987 {gpc_gb16,gpc_sGp, gpc_cb16,gpc_sCp, gpc_g16, gpc_g16q,gpc_A, gpc_noop}
1990 /* The error arrays record the error in the same matrix; 64 entries, however
1991 * the different algorithms used in libpng for colormap and direct conversions
1992 * mean that four separate matrices are used (for each combination of
1993 * colormapped and direct.)
1995 * In some cases the conversion between sRGB formats goes via a linear
1996 * intermediate; an sRGB to linear conversion (as above) is followed by a simple
1997 * linear to sRGB step with no other conversions. This is done by a separate
1998 * error array from an arbitrary 'in' format to one of the four basic outputs
1999 * (since final output is always sRGB not colormapped).
2001 * These arrays may be modified if the --accumulate flag is set during the run;
2002 * then instead of logging errors they are simply added in.
2004 * The three entries are currently for transparent, partially transparent and
2005 * opaque input pixel values. Notice that alpha should be exact in each case.
2007 * Errors in alpha should only occur when converting from a direct format
2008 * to a colormapped format, when alpha is effectively smashed (so large
2009 * errors can occur.) There should be no error in the '0' and 'opaque'
2010 * values. The fourth entry in the array is used for the alpha error (and it
2011 * should always be zero for the 'via linear' case since this is never color
2014 * Mapping to a colormap smashes the colors, it is necessary to have separate
2015 * values for these cases because they are much larger; it is very much
2016 * impossible to obtain a reasonable result, these are held in
2017 * gpc_error_to_colormap.
2019 #if PNG_FORMAT_FLAG_COLORMAP == 8 /* extra check also required */
2020 # include "pngstest-errors.h" /* machine generated */
2021 #endif /* COLORMAP flag check */
2022 #endif /* flag checks */
2026 /* Basic pixel information: */
2027 Image* in_image; /* Input image */
2028 const Image* out_image; /* Output image */
2030 /* 'background' is the value passed to the gpc_ routines, it may be NULL if
2031 * it should not be used (*this* program has an error if it crashes as a
2034 Background background_color;
2035 const Background* background;
2037 /* Precalculated values: */
2038 int in_opaque; /* Value of input alpha that is opaque */
2039 int is_palette; /* Sample values come from the palette */
2040 int accumulate; /* Accumulate component errors (don't log) */
2041 int output_8bit; /* Output is 8-bit (else 16-bit) */
2043 void (*in_gp)(Pixel*, png_const_voidp);
2044 void (*out_gp)(Pixel*, png_const_voidp);
2046 void (*transform)(Pixel *out, const Pixel *in, const Background *back);
2047 /* A function to perform the required transform */
2049 void (*from_linear)(Pixel *out, const Pixel *in, const Background *back);
2050 /* For 'via_linear' transforms the final, from linear, step, else NULL */
2052 png_uint_16 error[4];
2053 /* Three error values for transparent, partially transparent and opaque
2054 * input pixels (in turn).
2057 png_uint_16 *error_ptr;
2058 /* Where these are stored in the static array (for 'accumulate') */
2062 /* Return a 'transform' as above for the given format conversion. */
2064 transform_from_formats(Transform *result, Image *in_image,
2065 const Image *out_image, png_const_colorp background, int via_linear)
2067 png_uint_32 in_format, out_format;
2068 png_uint_32 in_base, out_base;
2070 memset(result, 0, sizeof *result);
2072 /* Store the original images for error messages */
2073 result->in_image = in_image;
2074 result->out_image = out_image;
2076 in_format = in_image->image.format;
2077 out_format = out_image->image.format;
2079 if (in_format & PNG_FORMAT_FLAG_LINEAR)
2080 result->in_opaque = 65535;
2082 result->in_opaque = 255;
2084 result->output_8bit = (out_format & PNG_FORMAT_FLAG_LINEAR) == 0;
2086 result->is_palette = 0; /* set by caller if required */
2087 result->accumulate = (in_image->opts & ACCUMULATE) != 0;
2089 /* The loaders (which need the ordering information) */
2090 result->in_gp = get_pixel(in_format);
2091 result->out_gp = get_pixel(out_format);
2093 /* Remove the ordering information: */
2094 in_format &= BASE_FORMATS | PNG_FORMAT_FLAG_COLORMAP;
2095 in_base = in_format & BASE_FORMATS;
2096 out_format &= BASE_FORMATS | PNG_FORMAT_FLAG_COLORMAP;
2097 out_base = out_format & BASE_FORMATS;
2101 /* Check for an error in this program: */
2102 if (out_format & (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLORMAP))
2104 fprintf(stderr, "internal transform via linear error 0x%x->0x%x\n",
2105 in_format, out_format);
2109 result->transform = gpc_fn[in_base][out_base | PNG_FORMAT_FLAG_LINEAR];
2110 result->from_linear = gpc_fn[out_base | PNG_FORMAT_FLAG_LINEAR][out_base];
2111 result->error_ptr = gpc_error_via_linear[in_format][out_format];
2114 else if (~in_format & out_format & PNG_FORMAT_FLAG_COLORMAP)
2116 /* The input is not colormapped but the output is, the errors will
2117 * typically be large (only the grayscale-no-alpha case permits preserving
2118 * even 8-bit values.)
2120 result->transform = gpc_fn[in_base][out_base];
2121 result->from_linear = NULL;
2122 result->error_ptr = gpc_error_to_colormap[in_base][out_base];
2127 /* The caller handles the colormap->pixel value conversion, so the
2128 * transform function just gets a pixel value, however because libpng
2129 * currently contains a different implementation for mapping a colormap if
2130 * both input and output are colormapped we need different conversion
2131 * functions to deal with errors in the libpng implementation.
2133 if (in_format & out_format & PNG_FORMAT_FLAG_COLORMAP)
2134 result->transform = gpc_fn_colormapped[in_base][out_base];
2136 result->transform = gpc_fn[in_base][out_base];
2137 result->from_linear = NULL;
2138 result->error_ptr = gpc_error[in_format][out_format];
2141 /* Follow the libpng simplified API rules to work out what to pass to the gpc
2142 * routines as a background value, if one is not required pass NULL so that
2143 * this program crashes in the even of a programming error.
2145 result->background = NULL; /* default: not required */
2147 /* Rule 1: background only need be supplied if alpha is to be removed */
2148 if (in_format & ~out_format & PNG_FORMAT_FLAG_ALPHA)
2150 /* The input value is 'NULL' to use the background and (otherwise) an sRGB
2151 * background color (to use a solid color). The code above uses a fixed
2152 * byte value, BUFFER_INIT8, for buffer even for 16-bit output. For
2153 * linear (16-bit) output the sRGB background color is ignored; the
2154 * composition is always on the background (so BUFFER_INIT8 * 257), except
2155 * that for the colormap (i.e. linear colormapped output) black is used.
2157 result->background = &result->background_color;
2159 if (out_format & PNG_FORMAT_FLAG_LINEAR || via_linear)
2161 if (out_format & PNG_FORMAT_FLAG_COLORMAP)
2163 result->background_color.ir =
2164 result->background_color.ig =
2165 result->background_color.ib = 0;
2166 result->background_color.dr =
2167 result->background_color.dg =
2168 result->background_color.db = 0;
2173 result->background_color.ir =
2174 result->background_color.ig =
2175 result->background_color.ib = BUFFER_INIT8 * 257;
2176 result->background_color.dr =
2177 result->background_color.dg =
2178 result->background_color.db = 0;
2182 else /* sRGB output */
2184 if (background != NULL)
2186 if (out_format & PNG_FORMAT_FLAG_COLOR)
2188 result->background_color.ir = background->red;
2189 result->background_color.ig = background->green;
2190 result->background_color.ib = background->blue;
2191 /* TODO: sometimes libpng uses the power law conversion here, how
2194 result->background_color.dr = sRGB_to_d[background->red];
2195 result->background_color.dg = sRGB_to_d[background->green];
2196 result->background_color.db = sRGB_to_d[background->blue];
2199 else /* grayscale: libpng only looks at 'g' */
2201 result->background_color.ir =
2202 result->background_color.ig =
2203 result->background_color.ib = background->green;
2204 /* TODO: sometimes libpng uses the power law conversion here, how
2207 result->background_color.dr =
2208 result->background_color.dg =
2209 result->background_color.db = sRGB_to_d[background->green];
2213 else if ((out_format & PNG_FORMAT_FLAG_COLORMAP) == 0)
2215 result->background_color.ir =
2216 result->background_color.ig =
2217 result->background_color.ib = BUFFER_INIT8;
2218 /* TODO: sometimes libpng uses the power law conversion here, how
2221 result->background_color.dr =
2222 result->background_color.dg =
2223 result->background_color.db = sRGB_to_d[BUFFER_INIT8];
2226 /* Else the output is colormapped and a background color must be
2227 * provided; if pngstest crashes then that is a bug in this program
2228 * (though libpng should png_error as well.)
2231 result->background = NULL;
2235 if (result->background == NULL)
2237 result->background_color.ir =
2238 result->background_color.ig =
2239 result->background_color.ib = -1; /* not used */
2240 result->background_color.dr =
2241 result->background_color.dg =
2242 result->background_color.db = 1E30; /* not used */
2246 /* Copy the error values into the Transform: */
2247 result->error[0] = result->error_ptr[0];
2248 result->error[1] = result->error_ptr[1];
2249 result->error[2] = result->error_ptr[2];
2250 result->error[3] = result->error_ptr[3];
2254 /* Compare two pixels.
2257 static int error_to_linear = 811; * by experiment *
2258 static int error_to_linear_grayscale = 424; * by experiment *
2259 static int error_to_sRGB = 6; * by experiment *
2260 static int error_to_sRGB_grayscale = 17; * libpng error by calculation +
2262 static int error_in_compose = 2; * by experiment *
2263 static int error_in_premultiply = 1;
2265 * The following is *just* the result of a round trip from 8-bit sRGB to linear
2266 * then back to 8-bit sRGB when it is done by libpng. There are two problems:
2268 * 1) libpng currently uses a 2.2 power law with no linear segment, this results
2269 * in instability in the low values and even with 16-bit precision sRGB(1) ends
2270 * up mapping to sRGB(0) as a result of rounding in the 16-bit representation.
2271 * This gives an error of 1 in the handling of value 1 only.
2273 * 2) libpng currently uses an intermediate 8-bit linear value in gamma
2274 * correction of 8-bit values. This results in many more errors, the worse of
2275 * which is mapping sRGB(14) to sRGB(0).
2277 * The general 'error_via_linear' is more complex because of pre-multiplication,
2278 * this compounds the 8-bit errors according to the alpha value of the pixel.
2279 * As a result 256 values are pre-calculated for error_via_linear.
2282 static int error_in_libpng_gamma;
2283 static int error_via_linear[256]; /* Indexed by 8-bit alpha */
2286 init_error_via_linear(void)
2290 error_via_linear[0] = 255; /* transparent pixel */
2292 for (alpha=1; alpha<=255; ++alpha)
2294 /* 16-bit values less than 128.5 get rounded to 8-bit 0 and so the worst
2295 * case error arises with 16-bit 128.5, work out what sRGB
2296 * (non-associated) value generates 128.5; any value less than this is
2297 * going to map to 0, so the worst error is floor(value).
2299 * Note that errors are considerably higher (more than a factor of 2)
2300 * because libpng uses a simple power law for sRGB data at present.
2302 * Add .1 for arithmetic errors inside libpng.
2304 double v = floor(255*pow(.5/*(128.5 * 255 / 65535)*/ / alpha, 1/2.2)+.1);
2306 error_via_linear[alpha] = (int)v;
2309 /* This is actually 14.99, but, despite the closeness to 15, 14 seems to work
2312 error_in_libpng_gamma = 14;
2317 print_pixel(char string[64], const Pixel *pixel, png_uint_32 format)
2319 switch (format & (PNG_FORMAT_FLAG_ALPHA|PNG_FORMAT_FLAG_COLOR))
2322 sprintf(string, "%s(%d)", format_names[format], pixel->g);
2325 case PNG_FORMAT_FLAG_ALPHA:
2326 sprintf(string, "%s(%d,%d)", format_names[format], pixel->g,
2330 case PNG_FORMAT_FLAG_COLOR:
2331 sprintf(string, "%s(%d,%d,%d)", format_names[format],
2332 pixel->r, pixel->g, pixel->b);
2335 case PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA:
2336 sprintf(string, "%s(%d,%d,%d,%d)", format_names[format],
2337 pixel->r, pixel->g, pixel->b, pixel->a);
2341 sprintf(string, "invalid-format");
2347 logpixel(const Transform *transform, png_uint_32 x, png_uint_32 y,
2348 const Pixel *in, const Pixel *calc, const Pixel *out, const char *reason)
2350 png_uint_32 in_format = transform->in_image->image.format;
2351 png_uint_32 out_format = transform->out_image->image.format;
2353 png_uint_32 back_format = out_format & ~PNG_FORMAT_FLAG_ALPHA;
2354 const char *via_linear = "";
2356 char pixel_in[64], pixel_calc[64], pixel_out[64], pixel_loc[64];
2357 char background_info[100];
2359 print_pixel(pixel_in, in, in_format);
2360 print_pixel(pixel_calc, calc, out_format);
2361 print_pixel(pixel_out, out, out_format);
2363 if (transform->is_palette)
2364 sprintf(pixel_loc, "palette: %lu", (unsigned long)y);
2366 sprintf(pixel_loc, "%lu,%lu", (unsigned long)x, (unsigned long)y);
2368 if (transform->from_linear != NULL)
2370 via_linear = " (via linear)";
2371 /* And as a result the *read* format which did any background processing
2372 * was itself linear, so the background color information is also
2375 back_format |= PNG_FORMAT_FLAG_LINEAR;
2378 if (transform->background != NULL)
2381 char pixel_back[64];
2383 back.r = transform->background->ir;
2384 back.g = transform->background->ig;
2385 back.b = transform->background->ib;
2386 back.a = -1; /* not used */
2388 print_pixel(pixel_back, &back, back_format);
2389 sprintf(background_info, " on background %s", pixel_back);
2393 background_info[0] = 0;
2395 if (transform->in_image->file_name != transform->out_image->file_name)
2397 char error_buffer[512];
2398 sprintf(error_buffer,
2399 "(%s) %s error%s:\n %s%s ->\n %s\n not: %s.\n"
2400 "Use --preserve and examine: ", pixel_loc, reason, via_linear,
2401 pixel_in, background_info, pixel_out, pixel_calc);
2402 return logerror(transform->in_image, transform->in_image->file_name,
2403 error_buffer, transform->out_image->file_name);
2408 char error_buffer[512];
2409 sprintf(error_buffer,
2410 "(%s) %s error%s:\n %s%s ->\n %s\n not: %s.\n"
2411 " The error happened when reading the original file with this format.",
2412 pixel_loc, reason, via_linear, pixel_in, background_info, pixel_out,
2414 return logerror(transform->in_image, transform->in_image->file_name,
2420 cmppixel(Transform *transform, png_const_voidp in, png_const_voidp out,
2421 png_uint_32 x, png_uint_32 y/*or palette index*/)
2424 png_const_charp errmsg;
2425 Pixel pixel_in, pixel_calc, pixel_out;
2427 transform->in_gp(&pixel_in, in);
2429 if (transform->from_linear == NULL)
2430 transform->transform(&pixel_calc, &pixel_in, transform->background);
2434 transform->transform(&pixel_out, &pixel_in, transform->background);
2435 transform->from_linear(&pixel_calc, &pixel_out, NULL);
2438 transform->out_gp(&pixel_out, out);
2440 /* Eliminate the case where the input and output values match exactly. */
2441 if (pixel_calc.a == pixel_out.a && pixel_calc.r == pixel_out.r &&
2442 pixel_calc.g == pixel_out.g && pixel_calc.b == pixel_out.b)
2445 /* Eliminate the case where the output pixel is transparent and the output
2446 * is 8-bit - any component values are valid. Don't check the input alpha
2447 * here to also skip the 16-bit small alpha cases.
2449 if (transform->output_8bit && pixel_calc.a == 0 && pixel_out.a == 0)
2452 /* Check for alpha errors first; an alpha error can damage the components too
2453 * so avoid spurious checks on components if one is found.
2457 int err_a = abs(pixel_calc.a-pixel_out.a);
2459 if (err_a > transform->error[3])
2461 /* If accumulating check the components too */
2462 if (transform->accumulate)
2463 transform->error[3] = (png_uint_16)err_a;
2470 /* Now if *either* of the output alphas are 0 but alpha is within tolerance
2471 * eliminate the 8-bit component comparison.
2473 if (errmsg == NULL && transform->output_8bit &&
2474 (pixel_calc.a == 0 || pixel_out.a == 0))
2477 if (errmsg == NULL) /* else just signal an alpha error */
2479 int err_r = abs(pixel_calc.r - pixel_out.r);
2480 int err_g = abs(pixel_calc.g - pixel_out.g);
2481 int err_b = abs(pixel_calc.b - pixel_out.b);
2484 if ((err_r | err_g | err_b) == 0)
2485 return 1; /* exact match */
2487 /* Mismatch on a component, check the input alpha */
2488 if (pixel_in.a >= transform->in_opaque)
2490 errmsg = "opaque component";
2491 limit = 2; /* opaque */
2494 else if (pixel_in.a > 0)
2496 errmsg = "alpha component";
2497 limit = 1; /* partially transparent */
2502 errmsg = "transparent component (background)";
2503 limit = 0; /* transparent */
2507 if (maxerr < err_g) maxerr = err_g;
2508 if (maxerr < err_b) maxerr = err_b;
2510 if (maxerr <= transform->error[limit])
2511 return 1; /* within the error limits */
2513 /* Handle a component mis-match; log it, just return an error code, or
2516 if (transform->accumulate)
2518 transform->error[limit] = (png_uint_16)maxerr;
2519 return 1; /* to cause the caller to keep going */
2523 /* Failure to match and not accumulating, so the error must be logged. */
2524 return logpixel(transform, x, y, &pixel_in, &pixel_calc, &pixel_out, errmsg);
2528 component_loc(png_byte loc[4], png_uint_32 format)
2530 /* Given a format return the number of channels and the location of
2533 * The mask 'loc' contains the component offset of the channels in the
2534 * following order. Note that if 'format' is grayscale the entries 1-3 must
2535 * all contain the location of the gray channel.
2544 if (format & PNG_FORMAT_FLAG_COLOR)
2550 # ifdef PNG_FORMAT_BGR_SUPPORTED
2551 if (format & PNG_FORMAT_FLAG_BGR)
2568 loc[1] = loc[2] = loc[3] = 0;
2571 if (format & PNG_FORMAT_FLAG_ALPHA)
2573 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
2574 if (format & PNG_FORMAT_FLAG_AFIRST)
2590 loc[0] = 4; /* not present */
2595 /* Compare two images, the original 'a', which was written out then read back in
2596 * to * give image 'b'. The formats may have been changed.
2599 compare_two_images(Image *a, Image *b, int via_linear,
2600 png_const_colorp background)
2602 ptrdiff_t stridea = a->stride;
2603 ptrdiff_t strideb = b->stride;
2604 png_const_bytep rowa = a->buffer+16;
2605 png_const_bytep rowb = b->buffer+16;
2606 png_uint_32 width = a->image.width;
2607 png_uint_32 height = a->image.height;
2608 png_uint_32 formata = a->image.format;
2609 png_uint_32 formatb = b->image.format;
2610 unsigned int a_sample = PNG_IMAGE_SAMPLE_SIZE(formata);
2611 unsigned int b_sample = PNG_IMAGE_SAMPLE_SIZE(formatb);
2612 int alpha_added, alpha_removed;
2616 int btoa[4]={0,0,0,0};
2618 /* This should never happen: */
2619 if (width != b->image.width || height != b->image.height)
2620 return logerror(a, a->file_name, ": width x height changed: ",
2623 /* Set up the background and the transform */
2624 transform_from_formats(&tr, a, b, background, via_linear);
2626 /* Find the first row and inter-row space. */
2627 if (!(formata & PNG_FORMAT_FLAG_COLORMAP) &&
2628 (formata & PNG_FORMAT_FLAG_LINEAR))
2631 if (!(formatb & PNG_FORMAT_FLAG_COLORMAP) &&
2632 (formatb & PNG_FORMAT_FLAG_LINEAR))
2635 if (stridea < 0) rowa += (height-1) * (-stridea);
2636 if (strideb < 0) rowb += (height-1) * (-strideb);
2638 /* First shortcut the two colormap case by comparing the image data; if it
2639 * matches then we expect the colormaps to match, although this is not
2640 * absolutely necessary for an image match. If the colormaps fail to match
2641 * then there is a problem in libpng.
2643 if (formata & formatb & PNG_FORMAT_FLAG_COLORMAP)
2645 /* Only check colormap entries that actually exist; */
2646 png_const_bytep ppa, ppb;
2648 png_byte in_use[256], amax = 0, bmax = 0;
2650 memset(in_use, 0, sizeof in_use);
2655 /* Do this the slow way to accumulate the 'in_use' flags, don't break out
2656 * of the loop until the end; this validates the color-mapped data to
2657 * ensure all pixels are valid color-map indexes.
2659 for (y=0, match=1; y<height && match; ++y, ppa += stridea, ppb += strideb)
2663 for (x=0; x<width; ++x)
2665 png_byte bval = ppb[x];
2666 png_byte aval = ppa[x];
2680 /* If the buffers match then the colormaps must too. */
2683 /* Do the color-maps match, entry by entry? Only check the 'in_use'
2684 * entries. An error here should be logged as a color-map error.
2686 png_const_bytep a_cmap = (png_const_bytep)a->colormap;
2687 png_const_bytep b_cmap = (png_const_bytep)b->colormap;
2688 int result = 1; /* match by default */
2690 /* This is used in logpixel to get the error message correct. */
2693 for (y=0; y<256; ++y, a_cmap += a_sample, b_cmap += b_sample)
2696 /* The colormap entries should be valid, but because libpng doesn't
2697 * do any checking at present the original image may contain invalid
2698 * pixel values. These cause an error here (at present) unless
2699 * accumulating errors in which case the program just ignores them.
2701 if (y >= a->image.colormap_entries)
2703 if ((a->opts & ACCUMULATE) == 0)
2706 sprintf(pindex, "%lu[%lu]", (unsigned long)y,
2707 (unsigned long)a->image.colormap_entries);
2708 logerror(a, a->file_name, ": bad pixel index: ", pindex);
2713 else if (y >= b->image.colormap_entries)
2715 if ((b->opts & ACCUMULATE) == 0)
2718 sprintf(pindex, "%lu[%lu]", (unsigned long)y,
2719 (unsigned long)b->image.colormap_entries);
2720 logerror(b, b->file_name, ": bad pixel index: ", pindex);
2725 /* All the mismatches are logged here; there can only be 256! */
2726 else if (!cmppixel(&tr, a_cmap, b_cmap, 0, y))
2730 /* If requested, copy the error values back from the Transform. */
2731 if (a->opts & ACCUMULATE)
2733 tr.error_ptr[0] = tr.error[0];
2734 tr.error_ptr[1] = tr.error[1];
2735 tr.error_ptr[2] = tr.error[2];
2736 tr.error_ptr[3] = tr.error[3];
2737 result = 1; /* force a continue */
2743 /* else the image buffers don't match pixel-wise so compare sample values
2744 * instead, but first validate that the pixel indexes are in range (but
2745 * only if not accumulating, when the error is ignored.)
2747 else if ((a->opts & ACCUMULATE) == 0)
2750 # define BYTE_CHARS 20 /* 2^32: GCC sprintf warning */
2752 # define BYTE_CHARS 3 /* 2^8: real maximum value */
2754 /* Check the original image first,
2755 * TODO: deal with input images with bad pixel values?
2757 if (amax >= a->image.colormap_entries)
2759 char pindex[3+2*BYTE_CHARS];
2760 sprintf(pindex, "%d[%u]", amax,
2761 (png_byte)/*SAFE*/a->image.colormap_entries);
2762 return logerror(a, a->file_name, ": bad pixel index: ", pindex);
2765 else if (bmax >= b->image.colormap_entries)
2767 char pindex[3+2*BYTE_CHARS];
2768 sprintf(pindex, "%d[%u]", bmax,
2769 (png_byte)/*SAFE*/b->image.colormap_entries);
2770 return logerror(b, b->file_name, ": bad pixel index: ", pindex);
2775 /* We can directly compare pixel values without the need to use the read
2776 * or transform support (i.e. a memory compare) if:
2778 * 1) The bit depth has not changed.
2779 * 2) RGB to grayscale has not been done (the reverse is ok; we just compare
2780 * the three RGB values to the original grayscale.)
2781 * 3) An alpha channel has not been removed from an 8-bit format, or the
2782 * 8-bit alpha value of the pixel was 255 (opaque).
2784 * If an alpha channel has been *added* then it must have the relevant opaque
2785 * value (255 or 65535).
2787 * The fist two the tests (in the order given above) (using the boolean
2788 * equivalence !a && !b == !(a || b))
2790 if (!(((formata ^ formatb) & PNG_FORMAT_FLAG_LINEAR) |
2791 (formata & (formatb ^ PNG_FORMAT_FLAG_COLOR) & PNG_FORMAT_FLAG_COLOR)))
2793 /* Was an alpha channel changed? */
2794 png_uint_32 alpha_changed = (formata ^ formatb) & PNG_FORMAT_FLAG_ALPHA;
2796 /* Was an alpha channel removed? (The third test.) If so the direct
2797 * comparison is only possible if the input alpha is opaque.
2799 alpha_removed = (formata & alpha_changed) != 0;
2801 /* Was an alpha channel added? */
2802 alpha_added = (formatb & alpha_changed) != 0;
2804 /* The channels may have been moved between input and output, this finds
2805 * out how, recording the result in the btoa array, which says where in
2806 * 'a' to find each channel of 'b'. If alpha was added then btoa[alpha]
2807 * ends up as 4 (and is not used.)
2814 /* The following are used only if the formats match, except that
2815 * 'bchannels' is a flag for matching formats. btoa[x] says, for each
2816 * channel in b, where to find the corresponding value in a, for the
2817 * bchannels. achannels may be different for a gray to rgb transform
2818 * (a will be 1 or 2, b will be 3 or 4 channels.)
2820 (void)component_loc(aloc, formata);
2821 bchannels = component_loc(bloc, formatb);
2823 /* Hence the btoa array. */
2827 btoa[bloc[i]] = aloc[i]; /* may be '4' for alpha */
2831 alpha_added = bloc[0]; /* location of alpha channel in image b */
2834 alpha_added = 4; /* Won't match an image b channel */
2837 alpha_removed = aloc[0]; /* location of alpha channel in image a */
2846 /* Direct compare is not possible, cancel out all the corresponding local
2850 alpha_removed = alpha_added = 4;
2851 btoa[3] = btoa[2] = btoa[1] = btoa[0] = 4; /* 4 == not present */
2854 for (y=0; y<height; ++y, rowa += stridea, rowb += strideb)
2856 png_const_bytep ppa, ppb;
2859 for (x=0, ppa=rowa, ppb=rowb; x<width; ++x)
2861 png_const_bytep psa, psb;
2863 if (formata & PNG_FORMAT_FLAG_COLORMAP)
2864 psa = (png_const_bytep)a->colormap + a_sample * *ppa++;
2866 psa = ppa, ppa += a_sample;
2868 if (formatb & PNG_FORMAT_FLAG_COLORMAP)
2869 psb = (png_const_bytep)b->colormap + b_sample * *ppb++;
2871 psb = ppb, ppb += b_sample;
2873 /* Do the fast test if possible. */
2876 /* Check each 'b' channel against either the corresponding 'a'
2877 * channel or the opaque alpha value, as appropriate. If
2878 * alpha_removed value is set (not 4) then also do this only if the
2879 * 'a' alpha channel (alpha_removed) is opaque; only relevant for
2882 if (formatb & PNG_FORMAT_FLAG_LINEAR) /* 16-bit checks */
2884 png_const_uint_16p pua = aligncastconst(png_const_uint_16p, psa);
2885 png_const_uint_16p pub = aligncastconst(png_const_uint_16p, psb);
2890 if (pua[btoa[3]] != pub[3]) break;
2893 if (pua[btoa[2]] != pub[2]) break;
2896 if (pua[btoa[1]] != pub[1]) break;
2899 if (pua[btoa[0]] != pub[0]) break;
2900 if (alpha_added != 4 && pub[alpha_added] != 65535) break;
2901 continue; /* x loop */
2903 break; /* impossible */
2907 else if (alpha_removed == 4 || psa[alpha_removed] == 255)
2912 if (psa[btoa[3]] != psb[3]) break;
2915 if (psa[btoa[2]] != psb[2]) break;
2918 if (psa[btoa[1]] != psb[1]) break;
2921 if (psa[btoa[0]] != psb[0]) break;
2922 if (alpha_added != 4 && psb[alpha_added] != 255) break;
2923 continue; /* x loop */
2925 break; /* impossible */
2930 /* If we get to here the fast match failed; do the slow match for this
2933 if (!cmppixel(&tr, psa, psb, x, y) && (a->opts & KEEP_GOING) == 0)
2934 return 0; /* error case */
2938 /* If requested, copy the error values back from the Transform. */
2939 if (a->opts & ACCUMULATE)
2941 tr.error_ptr[0] = tr.error[0];
2942 tr.error_ptr[1] = tr.error[1];
2943 tr.error_ptr[2] = tr.error[2];
2944 tr.error_ptr[3] = tr.error[3];
2950 /* Read the file; how the read gets done depends on which of input_file and
2951 * input_memory have been set.
2954 read_file(Image *image, png_uint_32 format, png_const_colorp background)
2956 memset(&image->image, 0, sizeof image->image);
2957 image->image.version = PNG_IMAGE_VERSION;
2959 if (image->input_memory != NULL)
2961 if (!png_image_begin_read_from_memory(&image->image, image->input_memory,
2962 image->input_memory_size))
2963 return logerror(image, "memory init: ", image->file_name, "");
2966 # ifdef PNG_STDIO_SUPPORTED
2967 else if (image->input_file != NULL)
2969 if (!png_image_begin_read_from_stdio(&image->image, image->input_file))
2970 return logerror(image, "stdio init: ", image->file_name, "");
2975 if (!png_image_begin_read_from_file(&image->image, image->file_name))
2976 return logerror(image, "file init: ", image->file_name, "");
2981 return logerror(image, "unsupported file/stdio init: ",
2982 image->file_name, "");
2986 /* This must be set after the begin_read call: */
2987 if (image->opts & sRGB_16BIT)
2988 image->image.flags |= PNG_IMAGE_FLAG_16BIT_sRGB;
2990 /* Have an initialized image with all the data we need plus, maybe, an
2991 * allocated file (myfile) or buffer (mybuffer) that need to be freed.
2995 png_uint_32 image_format;
2997 /* Print both original and output formats. */
2998 image_format = image->image.format;
3000 if (image->opts & VERBOSE)
3002 printf("%s %lu x %lu %s -> %s", image->file_name,
3003 (unsigned long)image->image.width,
3004 (unsigned long)image->image.height,
3005 format_names[image_format & FORMAT_MASK],
3006 (format & FORMAT_NO_CHANGE) != 0 || image->image.format == format
3007 ? "no change" : format_names[format & FORMAT_MASK]);
3009 if (background != NULL)
3010 printf(" background(%d,%d,%d)\n", background->red,
3011 background->green, background->blue);
3018 /* 'NO_CHANGE' combined with the color-map flag forces the base format
3019 * flags to be set on read to ensure that the original representation is
3020 * not lost in the pass through a colormap format.
3022 if ((format & FORMAT_NO_CHANGE) != 0)
3024 if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0 &&
3025 (image_format & PNG_FORMAT_FLAG_COLORMAP) != 0)
3026 format = (image_format & ~BASE_FORMATS) | (format & BASE_FORMATS);
3029 format = image_format;
3032 image->image.format = format;
3034 image->stride = PNG_IMAGE_ROW_STRIDE(image->image) + image->stride_extra;
3037 result = png_image_finish_read(&image->image, background,
3038 image->buffer+16, (png_int_32)image->stride, image->colormap);
3040 checkbuffer(image, image->file_name);
3043 return checkopaque(image);
3046 return logerror(image, image->file_name, ": image read failed", "");
3050 /* Reads from a filename, which must be in image->file_name, but uses
3051 * image->opts to choose the method. The file is always read in its native
3052 * format (the one the simplified API suggests).
3055 read_one_file(Image *image)
3057 if (!(image->opts & USE_FILE) || (image->opts & USE_STDIO))
3059 /* memory or stdio. */
3060 FILE *f = fopen(image->file_name, "rb");
3064 if (image->opts & USE_FILE)
3065 image->input_file = f;
3069 if (fseek(f, 0, SEEK_END) == 0)
3071 long int cb = ftell(f);
3075 #ifndef __COVERITY__
3076 if ((unsigned long int)cb <= (size_t)~(size_t)0)
3079 png_bytep b = voidcast(png_bytep, malloc((size_t)cb));
3085 if (fread(b, (size_t)cb, 1, f) == 1)
3088 image->input_memory_size = cb;
3089 image->input_memory = b;
3095 return logclose(image, f, image->file_name,
3101 return logclose(image, f, image->file_name,
3102 ": out of memory: ");
3106 return logclose(image, f, image->file_name,
3107 ": file too big for this architecture: ");
3108 /* cb is the length of the file as a (long) and
3109 * this is greater than the maximum amount of
3110 * memory that can be requested from malloc.
3115 return logclose(image, f, image->file_name,
3119 return logclose(image, f, image->file_name,
3124 return logclose(image, f, image->file_name, ": seek failed: ");
3129 return logerror(image, image->file_name, ": open failed: ",
3133 return read_file(image, FORMAT_NO_CHANGE, NULL);
3136 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
3138 write_one_file(Image *output, Image *image, int convert_to_8bit)
3140 if (image->opts & FAST_WRITE)
3141 image->image.flags |= PNG_IMAGE_FLAG_FAST;
3143 if (image->opts & USE_STDIO)
3145 #ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
3146 #ifndef __COVERITY__
3147 FILE *f = tmpfile();
3149 /* Experimental. Coverity says tmpfile() is insecure because it
3150 * generates predictable names.
3152 * It is possible to satisfy Coverity by using mkstemp(); however,
3153 * any platform supporting mkstemp() undoubtedly has a secure tmpfile()
3154 * implementation as well, and doesn't need the fix. Note that
3155 * the fix won't work on platforms that don't support mkstemp().
3157 * https://www.securecoding.cert.org/confluence/display/c/
3158 * FIO21-C.+Do+not+create+temporary+files+in+shared+directories
3159 * says that most historic implementations of tmpfile() provide
3160 * only a limited number of possible temporary file names
3161 * (usually 26) before file names are recycled. That article also
3162 * provides a secure solution that unfortunately depends upon mkstemp().
3164 char tmpfile[] = "pngstest-XXXXXX";
3168 filedes = mkstemp(tmpfile);
3173 f = fdopen(filedes,"w+");
3174 /* Hide the filename immediately and ensure that the file does
3175 * not exist after the program ends
3177 (void) unlink(tmpfile);
3183 if (png_image_write_to_stdio(&image->image, f, convert_to_8bit,
3184 image->buffer+16, (png_int_32)image->stride, image->colormap))
3189 initimage(output, image->opts, "tmpfile", image->stride_extra);
3190 output->input_file = f;
3191 if (!checkopaque(image))
3196 return logclose(image, f, "tmpfile", ": flush: ");
3202 return logerror(image, "tmpfile", ": write failed", "");
3207 return logerror(image, "tmpfile", ": open: ", strerror(errno));
3208 #else /* SIMPLIFIED_WRITE_STDIO */
3209 return logerror(image, "tmpfile", ": open: unsupported", "");
3210 #endif /* SIMPLIFIED_WRITE_STDIO */
3213 else if (image->opts & USE_FILE)
3215 #ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
3216 static unsigned int counter = 0;
3219 sprintf(name, "%s%u.png", tmpf, ++counter);
3221 if (png_image_write_to_file(&image->image, name, convert_to_8bit,
3222 image->buffer+16, (png_int_32)image->stride, image->colormap))
3224 initimage(output, image->opts, output->tmpfile_name,
3225 image->stride_extra);
3226 /* Afterwards, or freeimage will delete it! */
3227 strcpy(output->tmpfile_name, name);
3229 if (!checkopaque(image))
3234 return logerror(image, name, ": write failed", "");
3235 #else /* SIMPLIFIED_WRITE_STDIO */
3236 return logerror(image, "stdio", ": open: unsupported", "");
3237 #endif /* SIMPLIFIED_WRITE_STDIO */
3240 else /* use memory */
3242 png_alloc_size_t size;
3244 if (png_image_write_get_memory_size(image->image, size, convert_to_8bit,
3245 image->buffer+16, (png_int_32)image->stride, image->colormap))
3247 /* This is non-fatal but ignoring it was causing serious problems in
3248 * the macro to be ignored:
3250 if (size > PNG_IMAGE_PNG_SIZE_MAX(image->image))
3251 return logerror(image, "memory", ": PNG_IMAGE_SIZE_MAX wrong", "");
3253 initimage(output, image->opts, "memory", image->stride_extra);
3254 output->input_memory = malloc(size);
3256 if (output->input_memory != NULL)
3258 output->input_memory_size = size;
3260 if (png_image_write_to_memory(&image->image, output->input_memory,
3261 &output->input_memory_size, convert_to_8bit, image->buffer+16,
3262 (png_int_32)image->stride, image->colormap))
3264 /* This is also non-fatal but it safes safer to error out anyway:
3266 if (size != output->input_memory_size)
3267 return logerror(image, "memory", ": memory size wrong", "");
3271 return logerror(image, "memory", ": write failed", "");
3275 return logerror(image, "memory", ": out of memory", "");
3279 return logerror(image, "memory", ": get size:", "");
3282 /* 'output' has an initialized temporary image, read this back in and compare
3283 * this against the original: there should be no change since the original
3284 * format was written unmodified unless 'convert_to_8bit' was specified.
3285 * However, if the original image was color-mapped, a simple read will zap
3286 * the linear, color and maybe alpha flags, this will cause spurious failures
3287 * under some circumstances.
3289 if (read_file(output, image->image.format | FORMAT_NO_CHANGE, NULL))
3291 png_uint_32 original_format = image->image.format;
3293 if (convert_to_8bit)
3294 original_format &= ~PNG_FORMAT_FLAG_LINEAR;
3296 if ((output->image.format & BASE_FORMATS) !=
3297 (original_format & BASE_FORMATS))
3298 return logerror(image, image->file_name, ": format changed on read: ",
3301 return compare_two_images(image, output, 0/*via linear*/, NULL);
3305 return logerror(output, output->tmpfile_name,
3306 ": read of new file failed", "");
3311 testimage(Image *image, png_uint_32 opts, format_list *pf)
3316 /* Copy the original data, stealing it from 'image' */
3325 image->input_file = NULL;
3326 image->input_memory = NULL;
3327 image->input_memory_size = 0;
3328 image->tmpfile_name[0] = 0;
3331 png_uint_32 counter;
3338 /* Use the low bit of 'counter' to indicate whether or not to do alpha
3339 * removal with a background color or by composting onto the image; this
3340 * step gets skipped if it isn't relevant
3342 for (counter=0; counter<2*FORMAT_COUNT; ++counter)
3343 if (format_isset(pf, counter >> 1))
3345 png_uint_32 format = counter >> 1;
3347 png_color background_color;
3348 png_colorp background = NULL;
3350 /* If there is a format change that removes the alpha channel then
3351 * the background is relevant. If the output is 8-bit color-mapped
3352 * then a background color *must* be provided, otherwise there are
3353 * two tests to do - one with a color, the other with NULL. The
3354 * NULL test happens second.
3356 if ((counter & 1) == 0)
3358 if ((format & PNG_FORMAT_FLAG_ALPHA) == 0 &&
3359 (image->image.format & PNG_FORMAT_FLAG_ALPHA) != 0)
3361 /* Alpha/transparency will be removed, the background is
3362 * relevant: make it a color the first time
3364 random_color(&background_color);
3365 background = &background_color;
3367 /* BUT if the output is to a color-mapped 8-bit format then
3368 * the background must always be a color, so increment 'counter'
3369 * to skip the NULL test.
3371 if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0 &&
3372 (format & PNG_FORMAT_FLAG_LINEAR) == 0)
3376 /* Otherwise an alpha channel is not being eliminated, just leave
3377 * background NULL and skip the (counter & 1) NULL test.
3382 /* else just use NULL for background */
3385 copy.opts = opts; /* in case read_file needs to change it */
3387 result = read_file(©, format, background);
3391 /* Make sure the file just read matches the original file. */
3392 result = compare_two_images(image, ©, 0/*via linear*/, background);
3396 # ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
3397 /* Write the *copy* just made to a new file to make sure the write
3398 * side works ok. Check the conversion to sRGB if the copy is
3402 result = write_one_file(&output, ©, 0/*convert to 8bit*/);
3406 /* Validate against the original too; the background is needed here
3407 * as well so that compare_two_images knows what color was used.
3409 result = compare_two_images(image, &output, 0, background);
3413 if ((format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
3414 (format & PNG_FORMAT_FLAG_COLORMAP) == 0)
3416 /* 'output' is linear, convert to the corresponding sRGB format.
3419 result = write_one_file(&output, ©, 1/*convert to 8bit*/);
3423 /* This may involve a conversion via linear; in the ideal world
3424 * this would round-trip correctly, but libpng 1.5.7 is not the
3425 * ideal world so allow a drift (error_via_linear).
3427 * 'image' has an alpha channel but 'output' does not then there
3428 * will a strip-alpha-channel operation (because 'output' is
3429 * linear), handle this by composing on black when doing the
3432 result = compare_two_images(image, &output, 1/*via_linear*/,
3437 # endif /* PNG_SIMPLIFIED_WRITE_SUPPORTED */
3449 test_one_file(const char *file_name, format_list *formats, png_uint_32 opts,
3450 int stride_extra, int log_pass)
3455 if (!(opts & NO_RESEED))
3456 reseed(); /* ensure that the random numbers don't depend on file order */
3458 initimage(&image, opts, file_name, stride_extra);
3459 result = read_one_file(&image);
3461 result = testimage(&image, opts, formats);
3464 /* Ensure that stderr is flushed into any log file */
3475 # ifndef PNG_SIMPLIFIED_WRITE_SUPPORTED
3476 printf(" (no write)");
3480 printf(" %s\n", file_name);
3481 /* stdout may not be line-buffered if it is piped to a file, so: */
3492 main(int argc, char **argv)
3494 png_uint_32 opts = FAST_WRITE | STRICT;
3495 format_list formats;
3496 const char *touch = NULL;
3499 int stride_extra = 0;
3503 #if PNG_LIBPNG_VER >= 10700
3504 /* This error should not exist in 1.7 or later: */
3510 init_error_via_linear();
3512 format_init(&formats);
3513 reseed(); /* initialize random number seeds */
3515 for (c=1; c<argc; ++c)
3517 const char *arg = argv[c];
3519 if (strcmp(arg, "--log") == 0)
3521 else if (strcmp(arg, "--fresh") == 0)
3523 memset(gpc_error, 0, sizeof gpc_error);
3524 memset(gpc_error_via_linear, 0, sizeof gpc_error_via_linear);
3526 else if (strcmp(arg, "--file") == 0)
3527 # ifdef PNG_STDIO_SUPPORTED
3530 return SKIP; /* skipped: no support */
3532 else if (strcmp(arg, "--memory") == 0)
3534 else if (strcmp(arg, "--stdio") == 0)
3535 # ifdef PNG_STDIO_SUPPORTED
3538 return SKIP; /* skipped: no support */
3540 else if (strcmp(arg, "--name") == 0)
3542 else if (strcmp(arg, "--verbose") == 0)
3544 else if (strcmp(arg, "--quiet") == 0)
3546 else if (strcmp(arg, "--preserve") == 0)
3547 opts |= KEEP_TMPFILES;
3548 else if (strcmp(arg, "--nopreserve") == 0)
3549 opts &= ~KEEP_TMPFILES;
3550 else if (strcmp(arg, "--keep-going") == 0)
3552 else if (strcmp(arg, "--fast") == 0)
3554 else if (strcmp(arg, "--slow") == 0)
3555 opts &= ~FAST_WRITE;
3556 else if (strcmp(arg, "--accumulate") == 0)
3558 else if (strcmp(arg, "--redundant") == 0)
3560 else if (strcmp(arg, "--stop") == 0)
3561 opts &= ~KEEP_GOING;
3562 else if (strcmp(arg, "--strict") == 0)
3564 else if (strcmp(arg, "--nostrict") == 0)
3566 else if (strcmp(arg, "--sRGB-16bit") == 0)
3568 else if (strcmp(arg, "--linear-16bit") == 0)
3569 opts &= ~sRGB_16BIT;
3570 else if (strcmp(arg, "--noreseed") == 0)
3572 else if (strcmp(arg, "--fault-gbg-warning") == 0)
3574 else if (strcmp(arg, "--tmpfile") == 0)
3578 if (strlen(argv[++c]) >= sizeof tmpf)
3581 fprintf(stderr, "%s: %s is too long for a temp file prefix\n",
3586 /* Safe: checked above */
3587 strncpy(tmpf, argv[c], sizeof (tmpf)-1);
3593 fprintf(stderr, "%s: %s requires a temporary file prefix\n",
3598 else if (strcmp(arg, "--touch") == 0)
3606 fprintf(stderr, "%s: %s requires a file name argument\n",
3611 else if (arg[0] == '+')
3613 png_uint_32 format = formatof(arg+1);
3615 if (format > FORMAT_COUNT)
3618 format_set(&formats, format);
3620 else if (arg[0] == '-' && arg[1] != 0 && (arg[1] != '0' || arg[2] != 0))
3623 fprintf(stderr, "%s: unknown option: %s\n", argv[0], arg);
3628 if (format_is_initial(&formats))
3629 format_default(&formats, redundant);
3633 int term = (arg[1] == '0' ? 0 : '\n');
3634 unsigned int ich = 0;
3636 /* Loop reading files, use a static buffer to simplify this and just
3637 * stop if the name gets to long.
3639 static char buffer[4096];
3645 /* Don't allow '\0' in file names, and terminate with '\n' or,
3646 * for -0, just '\0' (use -print0 to find to make this work!)
3648 if (ch == EOF || ch == term || ch == 0)
3652 if (ich > 0 && !test_one_file(buffer, &formats, opts,
3653 stride_extra, log_pass))
3660 --ich; /* so that the increment below sets it to 0 again */
3664 buffer[ich] = (char)ch;
3665 } while (++ich < sizeof buffer);
3671 fprintf(stderr, "%s...%s: file name too long\n", buffer,
3677 else if (!test_one_file(arg, &formats, opts, stride_extra, log_pass))
3682 if (opts & ACCUMULATE)
3686 printf("/* contrib/libtests/pngstest-errors.h\n");
3688 printf(" * BUILT USING:" PNG_HEADER_VERSION_STRING);
3690 printf(" * This code is released under the libpng license.\n");
3691 printf(" * For conditions of distribution and use, see the disclaimer\n");
3692 printf(" * and license in png.h\n");
3694 printf(" * THIS IS A MACHINE GENERATED FILE: do not edit it directly!\n");
3695 printf(" * Instead run:\n");
3697 printf(" * pngstest --accumulate\n");
3699 printf(" * on as many PNG files as possible; at least PNGSuite and\n");
3700 printf(" * contrib/libtests/testpngs.\n");
3703 printf("static png_uint_16 gpc_error[16/*in*/][16/*out*/][4/*a*/] =\n");
3705 for (in=0; in<16; ++in)
3708 printf(" { /* input: %s */\n ", format_names[in]);
3709 for (out=0; out<16; ++out)
3713 for (alpha=0; alpha<4; ++alpha)
3715 printf(" %d", gpc_error[in][out][alpha]);
3716 if (alpha < 3) putchar(',');
3722 if (out % 4 == 3) printf("\n ");
3734 printf("static png_uint_16 gpc_error_via_linear[16][4/*out*/][4] =\n");
3736 for (in=0; in<16; ++in)
3739 printf(" { /* input: %s */\n ", format_names[in]);
3740 for (out=0; out<4; ++out)
3744 for (alpha=0; alpha<4; ++alpha)
3746 printf(" %d", gpc_error_via_linear[in][out][alpha]);
3747 if (alpha < 3) putchar(',');
3762 printf("static png_uint_16 gpc_error_to_colormap[8/*i*/][8/*o*/][4] =\n");
3764 for (in=0; in<8; ++in)
3767 printf(" { /* input: %s */\n ", format_names[in]);
3768 for (out=0; out<8; ++out)
3772 for (alpha=0; alpha<4; ++alpha)
3774 printf(" %d", gpc_error_to_colormap[in][out][alpha]);
3775 if (alpha < 3) putchar(',');
3781 if (out % 4 == 3) printf("\n ");
3792 printf("/* END MACHINE GENERATED */\n");
3795 if (retval == 0 && touch != NULL)
3797 FILE *fsuccess = fopen(touch, "wt");
3799 if (fsuccess != NULL)
3802 fprintf(fsuccess, "PNG simple API tests succeeded\n");
3804 error = ferror(fsuccess);
3806 if (fclose(fsuccess) || error)
3809 fprintf(stderr, "%s: write failed\n", touch);
3817 fprintf(stderr, "%s: open failed\n", touch);
3825 #else /* !PNG_SIMPLIFIED_READ_SUPPORTED */
3828 fprintf(stderr, "pngstest: no read support in libpng, test skipped\n");
3829 /* So the test is skipped: */
3832 #endif /* PNG_SIMPLIFIED_READ_SUPPORTED */