1 /*
2 * png2pnm.c --- conversion from PNG-file to PGM/PPM-file
3 * copyright (C) 1999-2019 by Willem van Schaik <willem at schaik dot com>
4 *
5 * This software is released under the MIT license. For conditions of
6 * distribution and use, see the LICENSE file part of this package.
7 */
8
9 #include <stdio.h>
10 #include <stdlib.h>
11 #include <fcntl.h>
12
13 #ifndef BOOL
14 #define BOOL unsigned char
15 #endif
16 #ifndef TRUE
17 #define TRUE (BOOL) 1
18 #endif
19 #ifndef FALSE
20 #define FALSE (BOOL) 0
21 #endif
22
23 /* make png2pnm verbose so we can find problems (needs to be before png.h) */
24 #ifndef PNG_DEBUG
25 #define PNG_DEBUG 0
26 #endif
27
28 #include "png.h"
29
30 /* function prototypes */
31
32 int main (int argc, char *argv[]);
33 void usage ();
34 BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
35 BOOL raw, BOOL alpha);
36
37 /*
38 * main
39 */
40
41 int main (int argc, char *argv[])
42 {
43 FILE *fp_rd = stdin;
44 FILE *fp_wr = stdout;
45 FILE *fp_al = NULL;
46 BOOL raw = TRUE;
47 BOOL alpha = FALSE;
48 int argi;
49
50 for (argi = 1; argi < argc; argi++)
51 {
52 if (argv[argi][0] == '-')
53 {
54 switch (argv[argi][1])
55 {
56 case 'n':
57 raw = FALSE;
58 break;
59 case 'r':
60 raw = TRUE;
61 break;
62 case 'a':
63 alpha = TRUE;
64 argi++;
65 if ((fp_al = fopen (argv[argi], "wb")) == NULL)
66 {
67 fprintf (stderr, "PNM2PNG\n");
68 fprintf (stderr, "Error: cannot create alpha-channel file %s\n",
69 argv[argi]);
70 exit (1);
71 }
72 break;
73 case 'h':
74 case '?':
75 usage ();
76 exit (0);
77 break;
78 default:
79 fprintf (stderr, "PNG2PNM\n");
80 fprintf (stderr, "Error: unknown option %s\n", argv[argi]);
81 usage ();
82 exit (1);
83 break;
84 } /* end switch */
85 }
86 else if (fp_rd == stdin)
87 {
88 if ((fp_rd = fopen (argv[argi], "rb")) == NULL)
89 {
90 fprintf (stderr, "PNG2PNM\n");
91 fprintf (stderr, "Error: file %s does not exist\n", argv[argi]);
92 exit (1);
93 }
94 }
95 else if (fp_wr == stdout)
96 {
97 if ((fp_wr = fopen (argv[argi], "wb")) == NULL)
98 {
99 fprintf (stderr, "PNG2PNM\n");
100 fprintf (stderr, "Error: cannot create file %s\n", argv[argi]);
101 exit (1);
102 }
103 }
104 else
105 {
106 fprintf (stderr, "PNG2PNM\n");
107 fprintf (stderr, "Error: too many parameters\n");
108 usage ();
109 exit (1);
110 }
111 } /* end for */
112
113 #if defined(O_BINARY) && (O_BINARY != 0)
114 /* set stdin/stdout if required to binary */
115 if (fp_rd == stdin)
116 setmode (fileno (stdin), O_BINARY);
117 if ((raw) && (fp_wr == stdout))
118 setmode (fileno (stdout), O_BINARY);
119 #endif
120
121 /* call the conversion program itself */
122 if (png2pnm (fp_rd, fp_wr, fp_al, raw, alpha) == FALSE)
123 {
124 fprintf (stderr, "PNG2PNM\n");
125 fprintf (stderr, "Error: unsuccessful conversion of PNG-image\n");
126 exit (1);
127 }
128
129 /* close input file */
130 fclose (fp_rd);
131 /* close output file */
132 fclose (fp_wr);
133 /* close alpha file */
134 if (alpha)
135 fclose (fp_al);
136
137 return 0;
138 }
139
140 /*
141 * usage
142 */
143
144 void usage ()
145 {
146 fprintf (stderr, "PNG2PNM\n");
147 fprintf (stderr, " by Willem van Schaik, 1999\n");
148 fprintf (stderr, "Usage: png2pnm [options] <file>.png [<file>.pnm]\n");
149 fprintf (stderr, " or: ... | png2pnm [options]\n");
150 fprintf (stderr, "Options:\n");
151 fprintf (stderr,
152 " -r[aw] write pnm-file in binary format (P4/P5/P6) (default)\n");
153 fprintf (stderr, " -n[oraw] write pnm-file in ascii format (P1/P2/P3)\n");
154 fprintf (stderr,
155 " -a[lpha] <file>.pgm write PNG alpha channel as pgm-file\n");
156 fprintf (stderr, " -h | -? print this help-information\n");
157 }
158
159 /*
160 * png2pnm
161 */
162
163 BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
164 BOOL raw, BOOL alpha)
165 {
166 png_struct *png_ptr = NULL;
167 png_info *info_ptr = NULL;
168 png_byte buf[8];
169 png_byte *png_pixels = NULL;
170 png_byte **row_pointers = NULL;
171 png_byte *pix_ptr = NULL;
172 png_uint_32 row_bytes;
173
174 png_uint_32 width;
175 png_uint_32 height;
176 int bit_depth;
177 int channels;
178 int color_type;
179 int alpha_present;
180 int row, col;
181 int ret;
182 int i;
183 long dep_16;
184
185 /* read and check signature in PNG file */
186 ret = fread (buf, 1, 8, png_file);
187 if (ret != 8)
188 return FALSE;
189
190 ret = png_sig_cmp (buf, 0, 8);
191 if (ret != 0)
192 return FALSE;
193
194 /* create png and info structures */
195
196 png_ptr = png_create_read_struct (png_get_libpng_ver(NULL),
197 NULL, NULL, NULL);
198 if (!png_ptr)
199 return FALSE; /* out of memory */
200
201 info_ptr = png_create_info_struct (png_ptr);
202 if (!info_ptr)
203 {
204 png_destroy_read_struct (&png_ptr, NULL, NULL);
205 return FALSE; /* out of memory */
206 }
207
208 if (setjmp (png_jmpbuf (png_ptr)))
209 {
210 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
211 return FALSE;
212 }
213
214 /* set up the input control for C streams */
215 png_init_io (png_ptr, png_file);
216 png_set_sig_bytes (png_ptr, 8); /* we already read the 8 signature bytes */
217
218 /* read the file information */
219 png_read_info (png_ptr, info_ptr);
220
221 /* get size and bit-depth of the PNG-image */
222 png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
223 NULL, NULL, NULL);
224
225 /* set-up the transformations */
226
227 /* transform paletted images into full-color rgb */
228 if (color_type == PNG_COLOR_TYPE_PALETTE)
229 png_set_expand (png_ptr);
230 /* expand images to bit-depth 8 (only applicable for grayscale images) */
231 if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
232 png_set_expand (png_ptr);
233 /* transform transparency maps into full alpha-channel */
234 if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
235 png_set_expand (png_ptr);
236
237 #ifdef NJET
238 /* downgrade 16-bit images to 8-bit */
239 if (bit_depth == 16)
240 png_set_strip_16 (png_ptr);
241 /* transform grayscale images into full-color */
242 if (color_type == PNG_COLOR_TYPE_GRAY ||
243 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
244 png_set_gray_to_rgb (png_ptr);
245 /* only if file has a file gamma, we do a correction */
246 if (png_get_gAMA (png_ptr, info_ptr, &file_gamma))
247 png_set_gamma (png_ptr, (double) 2.2, file_gamma);
248 #endif
249
250 /* all transformations have been registered; now update info_ptr data,
251 * get rowbytes and channels, and allocate image memory */
252
253 png_read_update_info (png_ptr, info_ptr);
254
255 /* get the new color-type and bit-depth (after expansion/stripping) */
256 png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
257 NULL, NULL, NULL);
258
259 /* check for 16-bit files */
260 if (bit_depth == 16)
261 {
262 raw = FALSE;
263 #if defined(O_BINARY) && (O_BINARY != 0)
264 setmode (fileno (pnm_file), O_BINARY);
265 #endif
266 }
267
268 /* calculate new number of channels and store alpha-presence */
269 if (color_type == PNG_COLOR_TYPE_GRAY)
270 channels = 1;
271 else if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
272 channels = 2;
273 else if (color_type == PNG_COLOR_TYPE_RGB)
274 channels = 3;
275 else if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
276 channels = 4;
277 else
278 channels = 0; /* should never happen */
279 alpha_present = (channels - 1) % 2;
280
281 /* check if alpha is expected to be present in file */
282 if (alpha && !alpha_present)
283 {
284 fprintf (stderr, "PNG2PNM\n");
285 fprintf (stderr, "Error: PNG-file doesn't contain alpha channel\n");
286 exit (1);
287 }
288
289 /* row_bytes is the width x number of channels x (bit-depth / 8) */
290 row_bytes = png_get_rowbytes (png_ptr, info_ptr);
291
292 if ((row_bytes == 0) ||
293 ((size_t) height > (size_t) (-1) / (size_t) row_bytes))
294 {
295 /* too big */
296 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
297 return FALSE;
298 }
299 if ((png_pixels = (png_byte *)
300 malloc ((size_t) row_bytes * (size_t) height)) == NULL)
301 {
302 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
303 return FALSE;
304 }
305
306 if ((row_pointers = (png_byte **)
307 malloc ((size_t) height * sizeof (png_byte *))) == NULL)
308 {
309 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
310 free (png_pixels);
311 return FALSE;
312 }
313
314 /* set the individual row_pointers to point at the correct offsets */
315 for (i = 0; i < ((int) height); i++)
316 row_pointers[i] = png_pixels + i * row_bytes;
317
318 /* now we can go ahead and just read the whole image */
319 png_read_image (png_ptr, row_pointers);
320
321 /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
322 png_read_end (png_ptr, info_ptr);
323
324 /* clean up after the read, and free any memory allocated - REQUIRED */
325 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
326
327 /* write header of PNM file */
328
329 if ((color_type == PNG_COLOR_TYPE_GRAY) ||
330 (color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
331 {
332 fprintf (pnm_file, "%s\n", (raw) ? "P5" : "P2");
333 fprintf (pnm_file, "%d %d\n", (int) width, (int) height);
334 fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
335 }
336 else if ((color_type == PNG_COLOR_TYPE_RGB) ||
337 (color_type == PNG_COLOR_TYPE_RGB_ALPHA))
338 {
339 fprintf (pnm_file, "%s\n", (raw) ? "P6" : "P3");
340 fprintf (pnm_file, "%d %d\n", (int) width, (int) height);
341 fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
342 }
343
344 /* write header of PGM file with alpha channel */
345
346 if ((alpha) &&
347 ((color_type == PNG_COLOR_TYPE_GRAY_ALPHA) ||
348 (color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
349 {
350 fprintf (alpha_file, "%s\n", (raw) ? "P5" : "P2");
351 fprintf (alpha_file, "%d %d\n", (int) width, (int) height);
352 fprintf (alpha_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
353 }
354
355 /* write data to PNM file */
356 pix_ptr = png_pixels;
357
358 for (row = 0; row < (int) height; row++)
359 {
360 for (col = 0; col < (int) width; col++)
361 {
362 for (i = 0; i < (channels - alpha_present); i++)
363 {
364 if (raw)
365 {
366 fputc ((int) *pix_ptr++, pnm_file);
367 }
368 else
369 {
370 if (bit_depth == 16)
371 {
372 dep_16 = (long) *pix_ptr++;
373 fprintf (pnm_file, "%ld ", (dep_16 << 8) + ((long) *pix_ptr++));
374 }
375 else
376 {
377 fprintf (pnm_file, "%ld ", (long) *pix_ptr++);
378 }
379 }
380 }
381 if (alpha_present)
382 {
383 if (!alpha)
384 {
385 pix_ptr++; /* alpha */
386 if (bit_depth == 16)
387 pix_ptr++;
388 }
389 else /* output alpha-channel as pgm file */
390 {
391 if (raw)
392 {
393 fputc ((int) *pix_ptr++, alpha_file);
394 }
395 else
396 {
397 if (bit_depth == 16)
398 {
399 dep_16 = (long) *pix_ptr++;
400 fprintf (alpha_file, "%ld ", (dep_16 << 8) + (long) *pix_ptr++);
401 }
402 else
403 {
404 fprintf (alpha_file, "%ld ", (long) *pix_ptr++);
405 }
406 }
407 }
408 } /* end if alpha_present */
409
410 if (!raw)
411 if (col % 4 == 3)
412 fprintf (pnm_file, "\n");
413 } /* end for col */
414
415 if (!raw)
416 if (col % 4 != 0)
417 fprintf (pnm_file, "\n");
418 } /* end for row */
419
420 if (row_pointers != NULL)
421 free (row_pointers);
422 if (png_pixels != NULL)
423 free (png_pixels);
424
425 return TRUE;
426
427 } /* end of source */