2 * png2pnm.c --- conversion from PNG-file to PGM/PPM-file
3 * copyright (C) 1999 by Willem van Schaik <willem@schaik.com>
5 * version 1.0 - 1999.10.15 - First version.
7 * Permission to use, copy, modify, and distribute this software and
8 * its documentation for any purpose and without fee is hereby granted,
9 * provided that the above copyright notice appear in all copies and
10 * that both that copyright notice and this permission notice appear in
11 * supporting documentation. This software is provided "as is" without
12 * express or implied warranty.
24 #define BOOL unsigned char
30 #define FALSE (BOOL) 0
39 /* to make png2pnm verbose so we can find problems (needs to be before png.h) */
46 /* Define png_jmpbuf() in case we are using a pre-1.0.6 version of libpng */
48 # define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
51 /* function prototypes */
53 int main (int argc, char *argv[]);
55 BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file, BOOL raw, BOOL alpha);
61 int main(int argc, char *argv[])
70 for (argi = 1; argi < argc; argi++)
72 if (argv[argi][0] == '-')
74 switch (argv[argi][1])
85 if ((fp_al = fopen (argv[argi], "wb")) == NULL)
87 fprintf (stderr, "PNM2PNG\n");
88 fprintf (stderr, "Error: can not create alpha-channel file %s\n", argv[argi]);
98 fprintf (stderr, "PNG2PNM\n");
99 fprintf (stderr, "Error: unknown option %s\n", argv[argi]);
105 else if (fp_rd == stdin)
107 if ((fp_rd = fopen (argv[argi], "rb")) == NULL)
109 fprintf (stderr, "PNG2PNM\n");
110 fprintf (stderr, "Error: file %s does not exist\n", argv[argi]);
114 else if (fp_wr == stdout)
116 if ((fp_wr = fopen (argv[argi], "wb")) == NULL)
118 fprintf (stderr, "PNG2PNM\n");
119 fprintf (stderr, "Error: can not create file %s\n", argv[argi]);
125 fprintf (stderr, "PNG2PNM\n");
126 fprintf (stderr, "Error: too many parameters\n");
133 /* set stdin/stdout if required to binary */
136 setmode (STDIN, O_BINARY);
138 if ((raw) && (fp_wr == stdout))
140 setmode (STDOUT, O_BINARY);
144 /* call the conversion program itself */
145 if (png2pnm (fp_rd, fp_wr, fp_al, raw, alpha) == FALSE)
147 fprintf (stderr, "PNG2PNM\n");
148 fprintf (stderr, "Error: unsuccessful conversion of PNG-image\n");
152 /* close input file */
154 /* close output file */
156 /* close alpha file */
169 fprintf (stderr, "PNG2PNM\n");
170 fprintf (stderr, " by Willem van Schaik, 1999\n");
172 fprintf (stderr, " for Turbo-C and Borland-C compilers\n");
174 fprintf (stderr, " for Linux (and Unix) compilers\n");
176 fprintf (stderr, "Usage: png2pnm [options] <file>.png [<file>.pnm]\n");
177 fprintf (stderr, " or: ... | png2pnm [options]\n");
178 fprintf (stderr, "Options:\n");
179 fprintf (stderr, " -r[aw] write pnm-file in binary format (P4/P5/P6) (default)\n");
180 fprintf (stderr, " -n[oraw] write pnm-file in ascii format (P1/P2/P3)\n");
181 fprintf (stderr, " -a[lpha] <file>.pgm write PNG alpha channel as pgm-file\n");
182 fprintf (stderr, " -h | -? print this help-information\n");
189 BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file, BOOL raw, BOOL alpha)
191 png_struct *png_ptr = NULL;
192 png_info *info_ptr = NULL;
194 png_byte *png_pixels = NULL;
195 png_byte **row_pointers = NULL;
196 png_byte *pix_ptr = NULL;
197 png_uint_32 row_bytes;
210 /* read and check signature in PNG file */
211 ret = fread (buf, 1, 8, png_file);
215 ret = png_sig_cmp (buf, 0, 8);
219 /* create png and info structures */
221 png_ptr = png_create_read_struct (PNG_LIBPNG_VER_STRING,
224 return FALSE; /* out of memory */
226 info_ptr = png_create_info_struct (png_ptr);
229 png_destroy_read_struct (&png_ptr, NULL, NULL);
230 return FALSE; /* out of memory */
233 if (setjmp (png_jmpbuf(png_ptr)))
235 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
239 /* set up the input control for C streams */
240 png_init_io (png_ptr, png_file);
241 png_set_sig_bytes (png_ptr, 8); /* we already read the 8 signature bytes */
243 /* read the file information */
244 png_read_info (png_ptr, info_ptr);
246 /* get size and bit-depth of the PNG-image */
247 png_get_IHDR (png_ptr, info_ptr,
248 &width, &height, &bit_depth, &color_type,
251 /* set-up the transformations */
253 /* transform paletted images into full-color rgb */
254 if (color_type == PNG_COLOR_TYPE_PALETTE)
255 png_set_expand (png_ptr);
256 /* expand images to bit-depth 8 (only applicable for grayscale images) */
257 if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
258 png_set_expand (png_ptr);
259 /* transform transparency maps into full alpha-channel */
260 if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
261 png_set_expand (png_ptr);
264 /* downgrade 16-bit images to 8 bit */
266 png_set_strip_16 (png_ptr);
267 /* transform grayscale images into full-color */
268 if (color_type == PNG_COLOR_TYPE_GRAY ||
269 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
270 png_set_gray_to_rgb (png_ptr);
271 /* only if file has a file gamma, we do a correction */
272 if (png_get_gAMA (png_ptr, info_ptr, &file_gamma))
273 png_set_gamma (png_ptr, (double) 2.2, file_gamma);
276 /* all transformations have been registered; now update info_ptr data,
277 * get rowbytes and channels, and allocate image memory */
279 png_read_update_info (png_ptr, info_ptr);
281 /* get the new color-type and bit-depth (after expansion/stripping) */
282 png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
285 /* check for 16-bit files */
290 pnm_file->flags &= ~((unsigned) _F_BIN);
294 /* calculate new number of channels and store alpha-presence */
295 if (color_type == PNG_COLOR_TYPE_GRAY)
297 else if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
299 else if (color_type == PNG_COLOR_TYPE_RGB)
301 else if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
304 channels = 0; /* should never happen */
305 alpha_present = (channels - 1) % 2;
307 /* check if alpha is expected to be present in file */
308 if (alpha && !alpha_present)
310 fprintf (stderr, "PNG2PNM\n");
311 fprintf (stderr, "Error: PNG-file doesn't contain alpha channel\n");
315 /* row_bytes is the width x number of channels x (bit-depth / 8) */
316 row_bytes = png_get_rowbytes (png_ptr, info_ptr);
318 if ((png_pixels = (png_byte *) malloc (row_bytes * height * sizeof (png_byte))) == NULL) {
319 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
323 if ((row_pointers = (png_byte **) malloc (height * sizeof (png_bytep))) == NULL)
325 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
331 /* set the individual row_pointers to point at the correct offsets */
332 for (i = 0; i < (height); i++)
333 row_pointers[i] = png_pixels + i * row_bytes;
335 /* now we can go ahead and just read the whole image */
336 png_read_image (png_ptr, row_pointers);
338 /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
339 png_read_end (png_ptr, info_ptr);
341 /* clean up after the read, and free any memory allocated - REQUIRED */
342 png_destroy_read_struct (&png_ptr, &info_ptr, (png_infopp) NULL);
344 /* write header of PNM file */
346 if ((color_type == PNG_COLOR_TYPE_GRAY) ||
347 (color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
349 fprintf (pnm_file, "%s\n", (raw) ? "P5" : "P2");
350 fprintf (pnm_file, "%d %d\n", (int) width, (int) height);
351 fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
353 else if ((color_type == PNG_COLOR_TYPE_RGB) ||
354 (color_type == PNG_COLOR_TYPE_RGB_ALPHA))
356 fprintf (pnm_file, "%s\n", (raw) ? "P6" : "P3");
357 fprintf (pnm_file, "%d %d\n", (int) width, (int) height);
358 fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
361 /* write header of PGM file with alpha channel */
364 ((color_type == PNG_COLOR_TYPE_GRAY_ALPHA) ||
365 (color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
367 fprintf (alpha_file, "%s\n", (raw) ? "P5" : "P2");
368 fprintf (alpha_file, "%d %d\n", (int) width, (int) height);
369 fprintf (alpha_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
372 /* write data to PNM file */
373 pix_ptr = png_pixels;
375 for (row = 0; row < height; row++)
377 for (col = 0; col < width; col++)
379 for (i = 0; i < (channels - alpha_present); i++)
382 fputc ((int) *pix_ptr++ , pnm_file);
384 if (bit_depth == 16){
385 dep_16 = (long) *pix_ptr++;
386 fprintf (pnm_file, "%ld ", (dep_16 << 8) + ((long) *pix_ptr++));
389 fprintf (pnm_file, "%ld ", (long) *pix_ptr++);
395 pix_ptr++; /* alpha */
399 else /* output alpha-channel as pgm file */
402 fputc ((int) *pix_ptr++ , alpha_file);
404 if (bit_depth == 16){
405 dep_16 = (long) *pix_ptr++;
406 fprintf (alpha_file, "%ld ", (dep_16 << 8) + (long) *pix_ptr++);
409 fprintf (alpha_file, "%ld ", (long) *pix_ptr++);
411 } /* if alpha_present */
415 fprintf (pnm_file, "\n");
420 fprintf (pnm_file, "\n");
423 if (row_pointers != (unsigned char**) NULL)
425 if (png_pixels != (unsigned char*) NULL)
430 } /* end of source */