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view libs/imago/file_rgbe.c @ 1:e7ca128b8713
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| author | John Tsiombikas <nuclear@member.fsf.org> |
|---|---|
| date | Sun, 02 Feb 2014 00:35:22 +0200 |
| parents | |
| children |
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1 /* This file contains code to read and write four byte rgbe file format
2 * developed by Greg Ward. It handles the conversions between rgbe and
3 * pixels consisting of floats. The data is assumed to be an array of floats.
4 * By default there are three floats per pixel in the order red, green, blue.
5 * (RGBE_DATA_??? values control this.)
6 *
7 * written by Bruce Walter (bjw@graphics.cornell.edu) 5/26/95
8 * based on code written by Greg Ward
9 * minor modifications by John Tsiombikas (nuclear@member.fsf.org) apr.9 2007
10 */
12 #include <stdio.h>
13 #include <stdlib.h>
14 #include <string.h>
15 #include <math.h>
16 #include <ctype.h>
17 #include <errno.h>
18 #include "imago2.h"
19 #include "ftype_module.h"
22 typedef struct {
23 int valid; /* indicate which fields are valid */
24 char programtype[16]; /* listed at beginning of file to identify it
25 * after "#?". defaults to "RGBE" */
26 float gamma; /* image has already been gamma corrected with
27 * given gamma. defaults to 1.0 (no correction) */
28 float exposure; /* a value of 1.0 in an image corresponds to
29 * <exposure> watts/steradian/m^2.
30 * defaults to 1.0 */
31 } rgbe_header_info;
34 static int check(struct img_io *io);
35 static int read(struct img_pixmap *img, struct img_io *io);
36 static int write(struct img_pixmap *img, struct img_io *io);
38 static int rgbe_read_header(struct img_io *io, int *width, int *height, rgbe_header_info * info);
39 static int rgbe_read_pixels_rle(struct img_io *io, float *data, int scanline_width, int num_scanlines);
42 int img_register_rgbe(void)
43 {
44 static struct ftype_module mod = {".rgbe", check, read, write};
45 return img_register_module(&mod);
46 }
49 static int check(struct img_io *io)
50 {
51 int xsz, ysz, res;
52 long pos = io->seek(0, SEEK_CUR, io->uptr);
54 rgbe_header_info hdr;
55 res = rgbe_read_header(io, &xsz, &ysz, &hdr);
57 io->seek(pos, SEEK_SET, io->uptr);
58 return res;
59 }
61 static int read(struct img_pixmap *img, struct img_io *io)
62 {
63 int xsz, ysz;
64 rgbe_header_info hdr;
66 if(rgbe_read_header(io, &xsz, &ysz, &hdr) == -1) {
67 return -1;
68 }
70 if(img_set_pixels(img, xsz, ysz, IMG_FMT_RGBF, 0) == -1) {
71 return -1;
72 }
73 if(rgbe_read_pixels_rle(io, img->pixels, xsz, ysz) == -1) {
74 return -1;
75 }
76 return 0;
77 }
79 static int write(struct img_pixmap *img, struct img_io *io)
80 {
81 return -1; /* TODO */
82 }
85 static int iofgetc(struct img_io *io)
86 {
87 char c;
88 return io->read(&c, 1, io->uptr) < 1 ? -1 : c;
89 }
91 static char *iofgets(char *buf, int size, struct img_io *io)
92 {
93 int c;
94 char *ptr = buf;
96 while(--size > 0 && (c = iofgetc(io)) != -1) {
97 *ptr++ = c;
98 if(c == '\n') break;
99 }
100 *ptr = 0;
102 return ptr == buf ? 0 : buf;
103 }
106 /* flags indicating which fields in an rgbe_header_info are valid */
107 #define RGBE_VALID_PROGRAMTYPE 0x01
108 #define RGBE_VALID_GAMMA 0x02
109 #define RGBE_VALID_EXPOSURE 0x04
111 /* return codes for rgbe routines */
112 #define RGBE_RETURN_SUCCESS 0
113 #define RGBE_RETURN_FAILURE -1
116 #if defined(__cplusplus) || defined(GNUC) || __STDC_VERSION >= 199901L
117 #define INLINE inline
118 #else
119 #define INLINE
120 #endif
122 /* offsets to red, green, and blue components in a data (float) pixel */
123 #define RGBE_DATA_RED 0
124 #define RGBE_DATA_GREEN 1
125 #define RGBE_DATA_BLUE 2
127 /* number of floats per pixel */
128 #define RGBE_DATA_SIZE 3
130 enum rgbe_error_codes {
131 rgbe_read_error,
132 rgbe_write_error,
133 rgbe_format_error,
134 rgbe_memory_error
135 };
138 /* default error routine. change this to change error handling */
139 static int rgbe_error(int rgbe_error_code, char *msg)
140 {
141 switch (rgbe_error_code) {
142 case rgbe_read_error:
143 fprintf(stderr, "RGBE read error: %s\n", strerror(errno));
144 break;
146 case rgbe_write_error:
147 fprintf(stderr, "RGBE write error: %s\n", strerror(errno));
148 break;
150 case rgbe_format_error:
151 fprintf(stderr, "RGBE bad file format: %s\n", msg);
152 break;
154 default:
155 case rgbe_memory_error:
156 fprintf(stderr, "RGBE error: %s\n", msg);
157 }
158 return RGBE_RETURN_FAILURE;
159 }
161 /* standard conversion from float pixels to rgbe pixels */
162 /*static INLINE void float2rgbe(unsigned char rgbe[4], float red, float green, float blue)
163 {
164 float v;
165 int e;
167 v = red;
168 if(green > v)
169 v = green;
170 if(blue > v)
171 v = blue;
172 if(v < 1e-32) {
173 rgbe[0] = rgbe[1] = rgbe[2] = rgbe[3] = 0;
174 } else {
175 v = frexp(v, &e) * 256.0 / v;
176 rgbe[0] = (unsigned char)(red * v);
177 rgbe[1] = (unsigned char)(green * v);
178 rgbe[2] = (unsigned char)(blue * v);
179 rgbe[3] = (unsigned char)(e + 128);
180 }
181 }*/
183 /* standard conversion from rgbe to float pixels */
184 /* note: Ward uses ldexp(col+0.5,exp-(128+8)). However we wanted pixels */
185 /* in the range [0,1] to map back into the range [0,1]. */
186 static INLINE void rgbe2float(float *red, float *green, float *blue, unsigned char rgbe[4])
187 {
188 float f;
190 if(rgbe[3]) { /*nonzero pixel */
191 f = ldexp(1.0, rgbe[3] - (int)(128 + 8));
192 *red = rgbe[0] * f;
193 *green = rgbe[1] * f;
194 *blue = rgbe[2] * f;
195 } else
196 *red = *green = *blue = 0.0;
197 }
199 #if 0
200 /* default minimal header. modify if you want more information in header */
201 static int rgbe_write_header(FILE * fp, int width, int height, rgbe_header_info * info)
202 {
203 char *programtype = "RGBE";
205 if(info && (info->valid & RGBE_VALID_PROGRAMTYPE))
206 programtype = info->programtype;
207 if(fprintf(fp, "#?%s\n", programtype) < 0)
208 return rgbe_error(rgbe_write_error, NULL);
209 /* The #? is to identify file type, the programtype is optional. */
210 if(info && (info->valid & RGBE_VALID_GAMMA)) {
211 if(fprintf(fp, "GAMMA=%g\n", info->gamma) < 0)
212 return rgbe_error(rgbe_write_error, NULL);
213 }
214 if(info && (info->valid & RGBE_VALID_EXPOSURE)) {
215 if(fprintf(fp, "EXPOSURE=%g\n", info->exposure) < 0)
216 return rgbe_error(rgbe_write_error, NULL);
217 }
218 if(fprintf(fp, "FORMAT=32-bit_rle_rgbe\n\n") < 0)
219 return rgbe_error(rgbe_write_error, NULL);
220 if(fprintf(fp, "-Y %d +X %d\n", height, width) < 0)
221 return rgbe_error(rgbe_write_error, NULL);
222 return RGBE_RETURN_SUCCESS;
223 }
224 #endif
226 /* minimal header reading. modify if you want to parse more information */
227 static int rgbe_read_header(struct img_io *io, int *width, int *height, rgbe_header_info * info)
228 {
229 char buf[128];
230 float tempf;
231 int i;
233 if(info) {
234 info->valid = 0;
235 info->programtype[0] = 0;
236 info->gamma = info->exposure = 1.0;
237 }
238 if(iofgets(buf, sizeof(buf) / sizeof(buf[0]), io) == NULL)
239 return RGBE_RETURN_FAILURE;/*rgbe_error(rgbe_read_error, NULL);*/
240 if((buf[0] != '#') || (buf[1] != '?')) {
241 /* if you want to require the magic token then uncomment the next line */
242 /*return rgbe_error(rgbe_format_error,"bad initial token"); */
243 } else if(info) {
244 info->valid |= RGBE_VALID_PROGRAMTYPE;
245 for(i = 0; i < sizeof(info->programtype) - 1; i++) {
246 if((buf[i + 2] == 0) || isspace(buf[i + 2]))
247 break;
248 info->programtype[i] = buf[i + 2];
249 }
250 info->programtype[i] = 0;
251 if(iofgets(buf, sizeof(buf) / sizeof(buf[0]), io) == 0)
252 return rgbe_error(rgbe_read_error, NULL);
253 }
254 for(;;) {
255 if((buf[0] == 0) || (buf[0] == '\n'))
256 return RGBE_RETURN_FAILURE;/*rgbe_error(rgbe_format_error, "no FORMAT specifier found");*/
257 else if(strcmp(buf, "FORMAT=32-bit_rle_rgbe\n") == 0)
258 break; /* format found so break out of loop */
259 else if(info && (sscanf(buf, "GAMMA=%g", &tempf) == 1)) {
260 info->gamma = tempf;
261 info->valid |= RGBE_VALID_GAMMA;
262 } else if(info && (sscanf(buf, "EXPOSURE=%g", &tempf) == 1)) {
263 info->exposure = tempf;
264 info->valid |= RGBE_VALID_EXPOSURE;
265 }
266 if(iofgets(buf, sizeof(buf) / sizeof(buf[0]), io) == 0)
267 return RGBE_RETURN_FAILURE;/*rgbe_error(rgbe_read_error, NULL);*/
268 }
269 if(iofgets(buf, sizeof(buf) / sizeof(buf[0]), io) == 0)
270 return RGBE_RETURN_FAILURE;/*rgbe_error(rgbe_read_error, NULL);*/
271 if(strcmp(buf, "\n") != 0)
272 return RGBE_RETURN_FAILURE;/*rgbe_error(rgbe_format_error, "missing blank line after FORMAT specifier");*/
273 if(iofgets(buf, sizeof(buf) / sizeof(buf[0]), io) == 0)
274 return RGBE_RETURN_FAILURE;/*rgbe_error(rgbe_read_error, NULL);*/
275 if(sscanf(buf, "-Y %d +X %d", height, width) < 2)
276 return RGBE_RETURN_FAILURE;/*rgbe_error(rgbe_format_error, "missing image size specifier");*/
277 return RGBE_RETURN_SUCCESS;
278 }
280 #if 0
281 /* simple write routine that does not use run length encoding */
283 /* These routines can be made faster by allocating a larger buffer and
284 fread-ing and fwrite-ing the data in larger chunks */
285 static int rgbe_write_pixels(FILE * fp, float *data, int numpixels)
286 {
287 unsigned char rgbe[4];
289 while(numpixels-- > 0) {
290 float2rgbe(rgbe, data[RGBE_DATA_RED], data[RGBE_DATA_GREEN], data[RGBE_DATA_BLUE]);
291 data += RGBE_DATA_SIZE;
292 if(fwrite(rgbe, sizeof(rgbe), 1, fp) < 1)
293 return rgbe_error(rgbe_write_error, NULL);
294 }
295 return RGBE_RETURN_SUCCESS;
296 }
297 #endif
299 /* simple read routine. will not correctly handle run length encoding */
300 static int rgbe_read_pixels(struct img_io *io, float *data, int numpixels)
301 {
302 unsigned char rgbe[4];
304 while(numpixels-- > 0) {
305 if(io->read(rgbe, sizeof(rgbe), io->uptr) < 1)
306 return rgbe_error(rgbe_read_error, NULL);
307 rgbe2float(&data[RGBE_DATA_RED], &data[RGBE_DATA_GREEN], &data[RGBE_DATA_BLUE], rgbe);
308 data += RGBE_DATA_SIZE;
309 }
310 return RGBE_RETURN_SUCCESS;
311 }
313 #if 0
314 /* The code below is only needed for the run-length encoded files. */
316 /* Run length encoding adds considerable complexity but does */
318 /* save some space. For each scanline, each channel (r,g,b,e) is */
320 /* encoded separately for better compression. */
322 static int rgbe_write_bytes_rle(struct img_io *io, unsigned char *data, int numbytes)
323 {
324 #define MINRUNLENGTH 4
325 int cur, beg_run, run_count, old_run_count, nonrun_count;
326 unsigned char buf[2];
328 cur = 0;
329 while(cur < numbytes) {
330 beg_run = cur;
331 /* find next run of length at least 4 if one exists */
332 run_count = old_run_count = 0;
333 while((run_count < MINRUNLENGTH) && (beg_run < numbytes)) {
334 beg_run += run_count;
335 old_run_count = run_count;
336 run_count = 1;
337 while((beg_run + run_count < numbytes) && (run_count < 127)
338 && (data[beg_run] == data[beg_run + run_count]))
339 run_count++;
340 }
341 /* if data before next big run is a short run then write it as such */
342 if((old_run_count > 1) && (old_run_count == beg_run - cur)) {
343 buf[0] = 128 + old_run_count; /*write short run */
344 buf[1] = data[cur];
345 if(fwrite(buf, sizeof(buf[0]) * 2, 1, fp) < 1)
346 return rgbe_error(rgbe_write_error, NULL);
347 cur = beg_run;
348 }
349 /* write out bytes until we reach the start of the next run */
350 while(cur < beg_run) {
351 nonrun_count = beg_run - cur;
352 if(nonrun_count > 128)
353 nonrun_count = 128;
354 buf[0] = nonrun_count;
355 if(fwrite(buf, sizeof(buf[0]), 1, fp) < 1)
356 return rgbe_error(rgbe_write_error, NULL);
357 if(fwrite(&data[cur], sizeof(data[0]) * nonrun_count, 1, fp) < 1)
358 return rgbe_error(rgbe_write_error, NULL);
359 cur += nonrun_count;
360 }
361 /* write out next run if one was found */
362 if(run_count >= MINRUNLENGTH) {
363 buf[0] = 128 + run_count;
364 buf[1] = data[beg_run];
365 if(fwrite(buf, sizeof(buf[0]) * 2, 1, fp) < 1)
366 return rgbe_error(rgbe_write_error, NULL);
367 cur += run_count;
368 }
369 }
370 return RGBE_RETURN_SUCCESS;
371 #undef MINRUNLENGTH
372 }
374 static int rgbe_write_pixels_rle(struct img_io *io, float *data, int scanline_width, int num_scanlines)
375 {
376 unsigned char rgbe[4];
377 unsigned char *buffer;
378 int i, err;
380 if((scanline_width < 8) || (scanline_width > 0x7fff))
381 /* run length encoding is not allowed so write flat */
382 return rgbe_write_pixels(io, data, scanline_width * num_scanlines);
383 buffer = (unsigned char *)malloc(sizeof(unsigned char) * 4 * scanline_width);
384 if(buffer == NULL)
385 /* no buffer space so write flat */
386 return rgbe_write_pixels(fp, data, scanline_width * num_scanlines);
387 while(num_scanlines-- > 0) {
388 rgbe[0] = 2;
389 rgbe[1] = 2;
390 rgbe[2] = scanline_width >> 8;
391 rgbe[3] = scanline_width & 0xFF;
392 if(fwrite(rgbe, sizeof(rgbe), 1, fp) < 1) {
393 free(buffer);
394 return rgbe_error(rgbe_write_error, NULL);
395 }
396 for(i = 0; i < scanline_width; i++) {
397 float2rgbe(rgbe, data[RGBE_DATA_RED], data[RGBE_DATA_GREEN], data[RGBE_DATA_BLUE]);
398 buffer[i] = rgbe[0];
399 buffer[i + scanline_width] = rgbe[1];
400 buffer[i + 2 * scanline_width] = rgbe[2];
401 buffer[i + 3 * scanline_width] = rgbe[3];
402 data += RGBE_DATA_SIZE;
403 }
404 /* write out each of the four channels separately run length encoded */
405 /* first red, then green, then blue, then exponent */
406 for(i = 0; i < 4; i++) {
407 if((err = rgbe_write_bytes_rle(fp, &buffer[i * scanline_width],
408 scanline_width)) != RGBE_RETURN_SUCCESS) {
409 free(buffer);
410 return err;
411 }
412 }
413 }
414 free(buffer);
415 return RGBE_RETURN_SUCCESS;
416 }
417 #endif
419 static int rgbe_read_pixels_rle(struct img_io *io, float *data, int scanline_width, int num_scanlines)
420 {
421 unsigned char rgbe[4], *scanline_buffer, *ptr, *ptr_end;
422 int i, count;
423 unsigned char buf[2];
425 if((scanline_width < 8) || (scanline_width > 0x7fff))
426 /* run length encoding is not allowed so read flat */
427 return rgbe_read_pixels(io, data, scanline_width * num_scanlines);
428 scanline_buffer = NULL;
429 /* read in each successive scanline */
430 while(num_scanlines > 0) {
431 if(io->read(rgbe, sizeof(rgbe), io->uptr) < 1) {
432 free(scanline_buffer);
433 return rgbe_error(rgbe_read_error, NULL);
434 }
435 if((rgbe[0] != 2) || (rgbe[1] != 2) || (rgbe[2] & 0x80)) {
436 /* this file is not run length encoded */
437 rgbe2float(&data[0], &data[1], &data[2], rgbe);
438 data += RGBE_DATA_SIZE;
439 free(scanline_buffer);
440 return rgbe_read_pixels(io, data, scanline_width * num_scanlines - 1);
441 }
442 if((((int)rgbe[2]) << 8 | rgbe[3]) != scanline_width) {
443 free(scanline_buffer);
444 return rgbe_error(rgbe_format_error, "wrong scanline width");
445 }
446 if(scanline_buffer == NULL)
447 scanline_buffer = (unsigned char *)
448 malloc(sizeof(unsigned char) * 4 * scanline_width);
449 if(scanline_buffer == NULL)
450 return rgbe_error(rgbe_memory_error, "unable to allocate buffer space");
452 ptr = &scanline_buffer[0];
453 /* read each of the four channels for the scanline into the buffer */
454 for(i = 0; i < 4; i++) {
455 ptr_end = &scanline_buffer[(i + 1) * scanline_width];
456 while(ptr < ptr_end) {
457 if(io->read(buf, sizeof(buf[0]) * 2, io->uptr) < 1) {
458 free(scanline_buffer);
459 return rgbe_error(rgbe_read_error, NULL);
460 }
461 if(buf[0] > 128) {
462 /* a run of the same value */
463 count = buf[0] - 128;
464 if((count == 0) || (count > ptr_end - ptr)) {
465 free(scanline_buffer);
466 return rgbe_error(rgbe_format_error, "bad scanline data");
467 }
468 while(count-- > 0)
469 *ptr++ = buf[1];
470 } else {
471 /* a non-run */
472 count = buf[0];
473 if((count == 0) || (count > ptr_end - ptr)) {
474 free(scanline_buffer);
475 return rgbe_error(rgbe_format_error, "bad scanline data");
476 }
477 *ptr++ = buf[1];
478 if(--count > 0) {
479 if(io->read(ptr, sizeof(*ptr) * count, io->uptr) < 1) {
480 free(scanline_buffer);
481 return rgbe_error(rgbe_read_error, NULL);
482 }
483 ptr += count;
484 }
485 }
486 }
487 }
488 /* now convert data from buffer into floats */
489 for(i = 0; i < scanline_width; i++) {
490 rgbe[0] = scanline_buffer[i];
491 rgbe[1] = scanline_buffer[i + scanline_width];
492 rgbe[2] = scanline_buffer[i + 2 * scanline_width];
493 rgbe[3] = scanline_buffer[i + 3 * scanline_width];
494 rgbe2float(&data[RGBE_DATA_RED], &data[RGBE_DATA_GREEN], &data[RGBE_DATA_BLUE], rgbe);
495 data += RGBE_DATA_SIZE;
496 }
497 num_scanlines--;
498 }
499 free(scanline_buffer);
500 return RGBE_RETURN_SUCCESS;
501 }