31 |
|
static int CLRCUBE[3][2] = {0,NRED,0,NGRN,0,NBLU}; |
32 |
|
/* maximum propagated error during dithering */ |
33 |
|
#define MAXERR 20 |
34 |
+ |
/* define CLOSEST to get closest colors */ |
35 |
+ |
#define CLOSEST 1 |
36 |
|
|
37 |
|
|
38 |
|
new_histo() /* clear our histogram */ |
68 |
|
ncolors = 256; |
69 |
|
/* partition color space */ |
70 |
|
cut(CLRCUBE, 0, ncolors); |
71 |
+ |
#ifdef CLOSEST |
72 |
+ |
closest(ncolors); /* ensure colors picked are closest */ |
73 |
+ |
#endif |
74 |
|
/* return new color table size */ |
75 |
|
return(ncolors); |
76 |
|
} |
258 |
|
clrtab[p][BLU] = (box[BLU][0]+box[BLU][1])*256/NBLU/2; |
259 |
|
} |
260 |
|
} |
261 |
+ |
|
262 |
+ |
|
263 |
+ |
#ifdef CLOSEST |
264 |
+ |
#define NBSIZ 32 |
265 |
+ |
static |
266 |
+ |
closest(n) /* make sure we have the closest colors */ |
267 |
+ |
int n; |
268 |
+ |
{ |
269 |
+ |
BYTE *neigh[256]; |
270 |
+ |
register int r, g, b; |
271 |
+ |
#define i r |
272 |
+ |
/* get space for neighbor lists */ |
273 |
+ |
for (i = 0; i < n; i++) { |
274 |
+ |
if ((neigh[i] = (BYTE *)malloc(NBSIZ)) == NULL) { |
275 |
+ |
while (i--) |
276 |
+ |
free(neigh[i]); |
277 |
+ |
return; /* ENOMEM -- abandon effort */ |
278 |
+ |
} |
279 |
+ |
neigh[i][0] = i; /* identity is terminator */ |
280 |
+ |
} |
281 |
+ |
/* make neighbor lists */ |
282 |
+ |
for (r = 0; r < NRED-1; r++) |
283 |
+ |
for (g = 0; g < NGRN-1; g++) |
284 |
+ |
for (b = 0; b < NBLU-1; b++) { |
285 |
+ |
if (histo[r][g][b] != histo[r+1][g][b]) |
286 |
+ |
addneigh(neigh, histo[r][g][b], histo[r+1][g][b]); |
287 |
+ |
if (histo[r][g][b] != histo[r][g+1][b]) |
288 |
+ |
addneigh(neigh, histo[r][g][b], histo[r][g+1][b]); |
289 |
+ |
if (histo[r][g][b] != histo[r][g][b+1]) |
290 |
+ |
addneigh(neigh, histo[r][g][b], histo[r][g][b+1]); |
291 |
+ |
} |
292 |
+ |
/* assign closest values */ |
293 |
+ |
for (r = 0; r < NRED; r++) |
294 |
+ |
for (g = 0; g < NGRN; g++) |
295 |
+ |
for (b = 0; b < NBLU; b++) |
296 |
+ |
setclosest(neigh, r, g, b); |
297 |
+ |
/* free neighbor lists */ |
298 |
+ |
for (i = 0; i < n; i++) |
299 |
+ |
free(neigh[i]); |
300 |
+ |
#undef i |
301 |
+ |
} |
302 |
+ |
|
303 |
+ |
|
304 |
+ |
static |
305 |
+ |
addneigh(nl, i, j) /* i and j are neighbors; add them to list */ |
306 |
+ |
register BYTE *nl[]; |
307 |
+ |
register int i; |
308 |
+ |
int j; |
309 |
+ |
{ |
310 |
+ |
int nc; |
311 |
+ |
char *nnl; |
312 |
+ |
register int t; |
313 |
+ |
|
314 |
+ |
for (nc = 0; nc < 2; nc++) { /* do both neighbors */ |
315 |
+ |
for (t = 0; nl[i][t] != i; t++) |
316 |
+ |
if (nl[i][t] == j) |
317 |
+ |
break; /* in list already */ |
318 |
+ |
if (nl[i][t] == i) { /* add to list */ |
319 |
+ |
nl[i][t++] = j; |
320 |
+ |
if (t % NBSIZ == 0) { /* enlarge list */ |
321 |
+ |
if ((nnl = realloc(nl[i], t+NBSIZ)) == NULL) |
322 |
+ |
t--; |
323 |
+ |
else |
324 |
+ |
nl[i] = (BYTE *)nnl; |
325 |
+ |
} |
326 |
+ |
nl[i][t] = i; /* terminator */ |
327 |
+ |
} |
328 |
+ |
t = i; i = j; j = t; /* swap and do it again */ |
329 |
+ |
} |
330 |
+ |
} |
331 |
+ |
|
332 |
+ |
|
333 |
+ |
static unsigned |
334 |
+ |
dist(col, r, g, b) /* find distance from clrtab entry to r,g,b */ |
335 |
+ |
register BYTE col[3]; |
336 |
+ |
int r, g, b; |
337 |
+ |
{ |
338 |
+ |
register unsigned tmp; |
339 |
+ |
register unsigned sum; |
340 |
+ |
|
341 |
+ |
tmp = col[RED]*NRED/256 - r; |
342 |
+ |
sum = tmp*tmp; |
343 |
+ |
tmp = col[GRN]*NGRN/256 - g; |
344 |
+ |
sum += tmp*tmp; |
345 |
+ |
tmp = col[BLU]*NBLU/256 - b; |
346 |
+ |
sum += tmp*tmp; |
347 |
+ |
return(sum); |
348 |
+ |
} |
349 |
+ |
|
350 |
+ |
|
351 |
+ |
static |
352 |
+ |
setclosest(nl, r, g, b) /* find index closest to color and assign */ |
353 |
+ |
BYTE *nl[]; |
354 |
+ |
int r, g, b; |
355 |
+ |
{ |
356 |
+ |
int ident; |
357 |
+ |
unsigned min; |
358 |
+ |
register unsigned d; |
359 |
+ |
register BYTE *p; |
360 |
+ |
/* get starting value */ |
361 |
+ |
min = dist(clrtab[ident=histo[r][g][b]], r, g, b); |
362 |
+ |
/* find minimum */ |
363 |
+ |
for (p = nl[ident]; *p != ident; p++) |
364 |
+ |
if ((d = dist(clrtab[*p], r, g, b)) < min) { |
365 |
+ |
min = d; |
366 |
+ |
histo[r][g][b] = *p; |
367 |
+ |
} |
368 |
+ |
} |
369 |
+ |
#endif |