3 * COPYRIGHT: Written by John Cunningham Bowler, 2011.
4 * To the extent possible under law, the author has waived all copyright and
5 * related or neighboring rights to this work. This work is published from:
8 * Extract any icc profiles found in the given PNG files. This is a simple
9 * example of a program that extracts information from the header of a PNG file
10 * without processing the image. Notice that some header information may occur
11 * after the image data. Textual data and comments are an example; the approach
12 * in this file won't work reliably for such data because it only looks for the
13 * information in the section of the file that preceeds the image data.
15 * Compile and link against libpng and zlib, plus anything else required on the
18 * To use supply a list of PNG files containing iCCP chunks, the chunks will be
19 * extracted to a similarly named file with the extension replaced by 'icc',
20 * which will be overwritten without warning.
29 static int verbose = 1;
30 static png_byte no_profile[] = "no profile";
33 extract(FILE *fp, png_uint_32 *proflen)
35 png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,0);
36 png_infop info_ptr = NULL;
37 png_bytep result = NULL;
39 /* Initialize for error or no profile: */
44 fprintf(stderr, "iccfrompng: version library mismatch?\n");
48 if (setjmp(png_jmpbuf(png_ptr)))
50 png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
54 png_init_io(png_ptr, fp);
56 info_ptr = png_create_info_struct(png_ptr);
58 png_error(png_ptr, "OOM allocating info structure");
60 png_read_info(png_ptr, info_ptr);
67 if (png_get_iCCP(png_ptr, info_ptr, &name, &compression_type, &profile,
68 proflen) & PNG_INFO_iCCP)
70 result = malloc(*proflen);
72 memcpy(result, profile, *proflen);
75 png_error(png_ptr, "OOM allocating profile buffer");
82 png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
87 extract_one_file(const char *filename)
90 FILE *fp = fopen(filename, "rb");
94 png_uint_32 proflen = 0;
95 png_bytep profile = extract(fp, &proflen);
97 if (profile != NULL && profile != no_profile)
103 const char *ep = strrchr(filename, '.');
109 len = strlen(filename);
112 output = malloc(len + 5);
117 memcpy(output, filename, len);
118 strcpy(output+len, ".icc");
120 of = fopen(output, "wb");
123 if (fwrite(profile, proflen, 1, of) == 1 &&
128 printf("%s -> %s\n", filename, output);
135 fprintf(stderr, "%s: error writing profile\n", output);
137 fprintf(stderr, "%s: could not remove file\n", output);
142 fprintf(stderr, "%s: failed to open output file\n", output);
148 fprintf(stderr, "%s: OOM allocating string!\n", filename);
153 else if (verbose && profile == no_profile)
154 printf("%s has no profile\n", filename);
158 fprintf(stderr, "%s: could not open file\n", filename);
164 main(int argc, char **argv)
169 for (i=1; i<argc; ++i)
171 if (strcmp(argv[i], "-q") == 0)
174 else if (extract_one_file(argv[i]))
178 /* Exit code is true if any extract succeeds */
179 return extracted == 0;