1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
|
/*
pnmhisteq.c
Equalize histogram for a PNM image
By Bryan Henderson 2005.09.10, based on ideas from the program of
the same name by John Walker (kelvin@fourmilab.ch) -- March MVM.
WWW home page: http://www.fourmilab.ch/ in 1995.
This program is contributed to the public domain by its author.
*/
#include <string.h>
#include "pm_c_util.h"
#include "pnm.h"
#include "shhopt.h"
#include "mallocvar.h"
struct cmdlineInfo {
/* All the information the user supplied in the command line,
in a form easy for the program to use.
*/
const char * inputFileName;
unsigned int gray;
const char * wmap;
const char * rmap;
unsigned int verbose;
};
static void
parseCommandLine(int argc, char ** argv,
struct cmdlineInfo * const cmdlineP) {
/*----------------------------------------------------------------------------
Note that the file spec array we return is stored in the storage that
was passed to us as the argv array.
-----------------------------------------------------------------------------*/
optEntry *option_def;
/* Instructions to optParseOptions3 on how to parse our options.
*/
optStruct3 opt;
unsigned int option_def_index;
unsigned int rmapSpec, wmapSpec;
MALLOCARRAY_NOFAIL(option_def, 100);
option_def_index = 0; /* incremented by OPTENT3 */
OPTENT3(0, "rmap", OPT_STRING, &cmdlineP->rmap,
&rmapSpec, 0);
OPTENT3(0, "wmap", OPT_STRING, &cmdlineP->wmap,
&wmapSpec, 0);
OPTENT3(0, "gray", OPT_FLAG, NULL,
&cmdlineP->gray, 0);
OPTENT3(0, "verbose", OPT_FLAG, NULL,
&cmdlineP->verbose, 0);
opt.opt_table = option_def;
opt.short_allowed = FALSE; /* We have no short (old-fashioned) options */
opt.allowNegNum = FALSE; /* We may have parms that are negative numbers */
optParseOptions3(&argc, argv, opt, sizeof(opt), 0);
/* Uses and sets argc, argv, and some of *cmdlineP and others. */
if (!wmapSpec)
cmdlineP->wmap = NULL;
if (!rmapSpec)
cmdlineP->rmap = NULL;
if (argc-1 < 1)
cmdlineP->inputFileName = "-";
else {
cmdlineP->inputFileName = argv[1];
if (argc-1 > 1)
pm_error("Too many arguments (%d). The only argument is the "
"input file name.", argc-1);
}
}
static void
computeLuminosityHistogram(xel * const * const xels,
unsigned int const rows,
unsigned int const cols,
xelval const maxval,
int const format,
bool const monoOnly,
unsigned int ** const lumahistP,
xelval * const lminP,
xelval * const lmaxP,
unsigned int * const pixelCountP) {
/*----------------------------------------------------------------------------
Scan the image and build the luminosity histogram. If the input is
a PPM, we calculate the luminosity of each pixel from its RGB
components.
-----------------------------------------------------------------------------*/
xelval lmin, lmax;
unsigned int pixelCount;
unsigned int * lumahist;
MALLOCARRAY(lumahist, maxval + 1);
if (lumahist == NULL)
pm_error("Out of storage allocating array for %u histogram elements",
maxval + 1);
{
unsigned int i;
/* Initialize histogram to zeroes everywhere */
for (i = 0; i <= maxval; ++i)
lumahist[i] = 0;
}
lmin = maxval; /* initial value */
lmax = 0; /* initial value */
switch (PNM_FORMAT_TYPE(format)) {
case PGM_TYPE:
case PBM_TYPE: {
/* Compute intensity histogram */
unsigned int row;
pixelCount = rows * cols;
for (row = 0; row < rows; ++row) {
unsigned int col;
for (col = 0; col < cols; ++col) {
xelval const l = PNM_GET1(xels[row][col]);
lmin = MIN(lmin, l);
lmax = MAX(lmax, l);
++lumahist[l];
}
}
}
break;
case PPM_TYPE: {
unsigned int row;
for (row = 0, pixelCount = 0; row < rows; ++row) {
unsigned int col;
for (col = 0; col < cols; ++col) {
xel const thisXel = xels[row][col];
if (!monoOnly || PPM_ISGRAY(thisXel)) {
xelval const l = PPM_LUMIN(thisXel);
lmin = MIN(lmin, l);
lmax = MAX(lmax, l);
++lumahist[l];
++pixelCount;
}
}
}
}
break;
default:
pm_error("invalid input format format");
}
*lumahistP = lumahist;
*pixelCountP = pixelCount;
*lminP = lmin;
*lmaxP = lmax;
}
static void
findMaxLuma(const xelval * const lumahist,
xelval const maxval,
xelval * const maxLumaP) {
xelval maxluma;
unsigned int i;
for (i = 0, maxluma = 0; i <= maxval; ++i)
if (lumahist[i] > 0)
maxluma = i;
*maxLumaP = maxluma;
}
static void
readMapFile(const char * const rmapFileName,
xelval const maxval,
gray * const lumamap) {
int rmcols, rmrows;
gray rmmaxv;
int rmformat;
FILE * rmapfP;
rmapfP = pm_openr(rmapFileName);
pgm_readpgminit(rmapfP, &rmcols, &rmrows, &rmmaxv, &rmformat);
if (rmmaxv != maxval)
pm_error("maxval in map file (%u) different from input (%u)",
rmmaxv, maxval);
if (rmrows != 1)
pm_error("Map must have 1 row. Yours has %u", rmrows);
if (rmcols != maxval + 1)
pm_error("Map must have maxval + 1 (%u) columns. Yours has %u",
maxval + 1, rmcols);
pgm_readpgmrow(rmapfP, lumamap, maxval+1, rmmaxv, rmformat);
pm_close(rmapfP);
}
static void
computeMap(const unsigned int * const lumahist,
xelval const maxval,
unsigned int const pixelCount,
gray * const lumamap) {
/* Calculate initial histogram equalization curve. */
unsigned int i;
unsigned int pixsum;
xelval maxluma;
for (i = 0, pixsum = 0; i <= maxval; ++i) {
/* With 16 bit grays, the following calculation can
overflow a 32 bit long. So, we do it in floating
point.
*/
lumamap[i] = ROUNDU((((double) pixsum * maxval)) / pixelCount);
pixsum += lumahist[i];
}
findMaxLuma(lumahist, maxval, &maxluma);
{
double const lscale = (double)maxval /
((lumahist[maxluma] > 0) ?
(double) lumamap[maxluma] : (double) maxval);
unsigned int i;
/* Normalize so that the brightest pixels are set to maxval. */
for (i = 0; i <= maxval; ++i)
lumamap[i] = MIN(maxval, ROUNDU(lumamap[i] * lscale));
}
}
static void
getMapping(const char * const rmapFileName,
const unsigned int * const lumahist,
xelval const maxval,
unsigned int const pixelCount,
gray ** const lumamapP) {
/*----------------------------------------------------------------------------
Calculate the luminosity mapping table which gives the
histogram-equalized luminosity for each original luminosity.
-----------------------------------------------------------------------------*/
gray * lumamap;
lumamap = pgm_allocrow(maxval+1);
if (rmapFileName)
readMapFile(rmapFileName, maxval, lumamap);
else
computeMap(lumahist, maxval, pixelCount, lumamap);
*lumamapP = lumamap;
}
static void
reportMap(const unsigned int * const lumahist,
xelval const maxval,
const gray * const lumamap) {
unsigned int i;
fprintf(stderr, " Luminosity map Number of\n");
fprintf(stderr, " Original New Pixels \n");
for (i = 0; i <= maxval; ++i) {
if (lumahist[i] > 0) {
fprintf(stderr,"%6d -> %6d %8u\n", i,
lumamap[i], lumahist[i]);
}
}
}
static xel
scaleXel(xel const thisXel,
double const scaler) {
/*----------------------------------------------------------------------------
Scale the components of 'xel' by multiplying by 'scaler'.
Assume this doesn't cause it to exceed maxval.
-----------------------------------------------------------------------------*/
xel retval;
PNM_ASSIGN(retval,
((xelval)(PNM_GETR(thisXel) * scaler + 0.5)),
((xelval)(PNM_GETG(thisXel) * scaler + 0.5)),
((xelval)(PNM_GETB(thisXel) * scaler + 0.5)));
return retval;
}
static xel
remapRgbValue(xel const thisXel,
xelval const maxval,
const gray * const lumamap) {
/*----------------------------------------------------------------------------
Return the color 'thisXel' with its HSV value changed per 'lumamap' but
the same hue and saturation.
'maxval' is the maxval for 'xel' and our return value.
-----------------------------------------------------------------------------*/
struct hsv const hsv =
ppm_hsv_from_color(thisXel, maxval);
xelval const oldValue =
MIN(maxval, ROUNDU(hsv.v * maxval));
xelval const newValue =
lumamap[oldValue];
return scaleXel(thisXel, (double)newValue/oldValue);
}
static void
remap(xel ** const xels,
unsigned int const cols,
unsigned int const rows,
xelval const maxval,
int const format,
bool const monoOnly,
const gray * const lumamap) {
/*----------------------------------------------------------------------------
Update the array 'xels' to have the new intensities.
-----------------------------------------------------------------------------*/
switch (PNM_FORMAT_TYPE(format)) {
case PPM_TYPE: {
unsigned int row;
for (row = 0; row < rows; ++row) {
unsigned int col;
for (col = 0; col < cols; ++col) {
xel const thisXel = xels[row][col];
if (monoOnly && PPM_ISGRAY(thisXel)) {
/* Leave this pixel alone */
} else {
xels[row][col] = remapRgbValue(xels[row][col],
maxval, lumamap);
}
}
}
}
break;
case PBM_TYPE:
case PGM_TYPE: {
unsigned int row;
for (row = 0; row < rows; ++row) {
unsigned int col;
for (col = 0; col < cols; ++col)
PNM_ASSIGN1(xels[row][col],
lumamap[PNM_GET1(xels[row][col])]);
}
}
break;
}
}
static void
writeMap(const char * const wmapFileName,
const gray * const lumamap,
xelval const maxval) {
FILE * const wmapfP = pm_openw(wmapFileName);
pgm_writepgminit(wmapfP, maxval+1, 1, maxval, 0);
pgm_writepgmrow(wmapfP, lumamap, maxval+1, maxval, 0);
pm_close(wmapfP);
}
int
main(int argc, char * argv[]) {
struct cmdlineInfo cmdline;
FILE * ifP;
xelval lmin, lmax;
gray * lumamap; /* Luminosity map */
unsigned int * lumahist; /* Histogram of luminosity values */
int rows, cols; /* Rows, columns of input image */
xelval maxval; /* Maxval of input image */
int format; /* Format indicator (PBM/PGM/PPM) */
xel ** xels; /* Pixel array */
unsigned int pixelCount;
pnm_init(&argc, argv);
parseCommandLine(argc, argv, &cmdline);
ifP = pm_openr(cmdline.inputFileName);
xels = pnm_readpnm(ifP, &cols, &rows, &maxval, &format);
pm_close(ifP);
computeLuminosityHistogram(xels, rows, cols, maxval, format,
cmdline.gray, &lumahist, &lmin, &lmax,
&pixelCount);
getMapping(cmdline.rmap, lumahist, maxval, pixelCount, &lumamap);
if (cmdline.verbose)
reportMap(lumahist, maxval, lumamap);
remap(xels, cols, rows, maxval, format, !!cmdline.gray, lumamap);
pnm_writepnm(stdout, xels, cols, rows, maxval, format, 0);
if (cmdline.wmap)
writeMap(cmdline.wmap, lumamap, maxval);
pgm_freerow(lumamap);
return 0;
}
|