| 1 |
/* Copyright (c) 1989 Regents of the University of California */ |
| 2 |
|
| 3 |
#ifndef lint |
| 4 |
static char SCCSid[] = "$SunId$ LBL"; |
| 5 |
#endif |
| 6 |
|
| 7 |
/* |
| 8 |
* colortab.c - allocate and control dynamic color table. |
| 9 |
* |
| 10 |
* We start off with a uniform partition of color space. |
| 11 |
* As pixels are sent to the frame buffer, a histogram is built. |
| 12 |
* When a new color table is requested, the histogram is used |
| 13 |
* to make a pseudo-optimal partition, after which the |
| 14 |
* histogram is cleared. This algorithm |
| 15 |
* performs only as well as the next drawing's color |
| 16 |
* distribution is correlated to the last. |
| 17 |
*/ |
| 18 |
|
| 19 |
#include "color.h" |
| 20 |
|
| 21 |
#define NULL 0 |
| 22 |
/* histogram resolution */ |
| 23 |
#define NRED 24 |
| 24 |
#define NGRN 32 |
| 25 |
#define NBLU 16 |
| 26 |
#define HMAX NGRN |
| 27 |
/* minimum box count for adaptive partition */ |
| 28 |
#define MINSAMP 7 |
| 29 |
/* maximum distance^2 before color reassign */ |
| 30 |
#define MAXDST2 12 |
| 31 |
/* map a color */ |
| 32 |
#define map_col(c,p) clrmap[p][ colval(c,p)<1. ? \ |
| 33 |
(int)(colval(c,p)*256.) : 255 ] |
| 34 |
/* color partition tree */ |
| 35 |
#define CNODE short |
| 36 |
#define set_branch(p,c) ((c)<<2|(p)) |
| 37 |
#define set_pval(pv) ((pv)<<2|3) |
| 38 |
#define is_branch(cn) (((cn)&3)!=3) |
| 39 |
#define is_pval(cn) (((cn)&3)==3) |
| 40 |
#define part(cn) ((cn)>>2) |
| 41 |
#define prim(cn) ((cn)&3) |
| 42 |
#define pval(cn) ((cn)>>2) |
| 43 |
/* our color table */ |
| 44 |
static struct tabent { |
| 45 |
long sum[3]; /* sum of colors using this entry */ |
| 46 |
long n; /* number of colors */ |
| 47 |
short ent[3]; /* current table value */ |
| 48 |
} *clrtab = NULL; |
| 49 |
/* color cube partition */ |
| 50 |
static CNODE *ctree = NULL; |
| 51 |
/* our color correction map */ |
| 52 |
static BYTE clrmap[3][256]; |
| 53 |
/* histogram of colors used */ |
| 54 |
static unsigned short histo[NRED][NGRN][NBLU]; |
| 55 |
/* initial color cube boundary */ |
| 56 |
static int CLRCUBE[3][2] = {0,NRED,0,NGRN,0,NBLU}; |
| 57 |
|
| 58 |
|
| 59 |
int |
| 60 |
new_ctab(ncolors) /* start new color table with max ncolors */ |
| 61 |
int ncolors; |
| 62 |
{ |
| 63 |
int treesize; |
| 64 |
|
| 65 |
if (ncolors < 1) |
| 66 |
return(0); |
| 67 |
/* free old tables */ |
| 68 |
if (clrtab != NULL) |
| 69 |
free((char *)clrtab); |
| 70 |
if (ctree != NULL) |
| 71 |
free((char *)ctree); |
| 72 |
/* get new tables */ |
| 73 |
for (treesize = 1; treesize < ncolors; treesize <<= 1) |
| 74 |
; |
| 75 |
treesize <<= 1; |
| 76 |
clrtab = (struct tabent *)calloc(ncolors, sizeof(struct tabent)); |
| 77 |
ctree = (CNODE *)malloc(treesize*sizeof(CNODE)); |
| 78 |
if (clrtab == NULL || ctree == NULL) |
| 79 |
return(0); |
| 80 |
/* partition color space */ |
| 81 |
cut(ctree, 0, CLRCUBE, 0, ncolors); |
| 82 |
/* clear histogram */ |
| 83 |
bzero(histo, sizeof(histo)); |
| 84 |
/* return number of colors used */ |
| 85 |
return(ncolors); |
| 86 |
} |
| 87 |
|
| 88 |
|
| 89 |
int |
| 90 |
get_pixel(col, set_pixel) /* get pixel for color */ |
| 91 |
COLOR col; |
| 92 |
int (*set_pixel)(); |
| 93 |
{ |
| 94 |
int r, g, b; |
| 95 |
int cv[3]; |
| 96 |
register CNODE *tp; |
| 97 |
register int h; |
| 98 |
/* map color */ |
| 99 |
r = map_col(col,RED); |
| 100 |
g = map_col(col,GRN); |
| 101 |
b = map_col(col,BLU); |
| 102 |
/* reduce resolution */ |
| 103 |
cv[RED] = (r*NRED)>>8; |
| 104 |
cv[GRN] = (g*NGRN)>>8; |
| 105 |
cv[BLU] = (b*NBLU)>>8; |
| 106 |
/* add to histogram */ |
| 107 |
histo[cv[RED]][cv[GRN]][cv[BLU]]++; |
| 108 |
/* find pixel in tree */ |
| 109 |
for (tp = ctree, h = 0; is_branch(*tp); h++) |
| 110 |
if (cv[prim(*tp)] < part(*tp)) |
| 111 |
tp += 1<<h; /* left branch */ |
| 112 |
else |
| 113 |
tp += 1<<(h+1); /* right branch */ |
| 114 |
h = pval(*tp); |
| 115 |
/* add to color table */ |
| 116 |
clrtab[h].sum[RED] += r; |
| 117 |
clrtab[h].sum[GRN] += g; |
| 118 |
clrtab[h].sum[BLU] += b; |
| 119 |
clrtab[h].n++; |
| 120 |
/* recompute average */ |
| 121 |
r = clrtab[h].sum[RED] / clrtab[h].n; |
| 122 |
g = clrtab[h].sum[GRN] / clrtab[h].n; |
| 123 |
b = clrtab[h].sum[BLU] / clrtab[h].n; |
| 124 |
/* check for movement */ |
| 125 |
if (clrtab[h].n == 1 || |
| 126 |
(r-clrtab[h].ent[RED])*(r-clrtab[h].ent[RED]) + |
| 127 |
(g-clrtab[h].ent[GRN])*(g-clrtab[h].ent[GRN]) + |
| 128 |
(b-clrtab[h].ent[BLU])*(b-clrtab[h].ent[BLU]) > MAXDST2) { |
| 129 |
clrtab[h].ent[RED] = r; |
| 130 |
clrtab[h].ent[GRN] = g; /* reassign pixel */ |
| 131 |
clrtab[h].ent[BLU] = b; |
| 132 |
#ifdef notdef |
| 133 |
printf("pixel %d = (%d,%d,%d) (%d refs)\n", |
| 134 |
h, r, g, b, clrtab[h].n); |
| 135 |
#endif |
| 136 |
(*set_pixel)(h, r, g, b); |
| 137 |
} |
| 138 |
return(h); /* return pixel value */ |
| 139 |
} |
| 140 |
|
| 141 |
|
| 142 |
make_gmap(gam) /* make gamma correction map */ |
| 143 |
double gam; |
| 144 |
{ |
| 145 |
extern double pow(); |
| 146 |
register int i; |
| 147 |
|
| 148 |
for (i = 0; i < 256; i++) |
| 149 |
clrmap[RED][i] = |
| 150 |
clrmap[GRN][i] = |
| 151 |
clrmap[BLU][i] = 256.0 * pow(i/256.0, 1.0/gam); |
| 152 |
} |
| 153 |
|
| 154 |
|
| 155 |
set_cmap(rmap, gmap, bmap) /* set custom color correction map */ |
| 156 |
BYTE *rmap, *gmap, *bmap; |
| 157 |
{ |
| 158 |
bcopy(rmap, clrmap[RED], 256); |
| 159 |
bcopy(gmap, clrmap[GRN], 256); |
| 160 |
bcopy(bmap, clrmap[BLU], 256); |
| 161 |
} |
| 162 |
|
| 163 |
|
| 164 |
static |
| 165 |
cut(tree, level, box, c0, c1) /* partition color space */ |
| 166 |
register CNODE *tree; |
| 167 |
int level; |
| 168 |
register int box[3][2]; |
| 169 |
int c0, c1; |
| 170 |
{ |
| 171 |
int kb[3][2]; |
| 172 |
|
| 173 |
if (c1-c0 <= 1) { /* assign pixel */ |
| 174 |
*tree = set_pval(c0); |
| 175 |
return; |
| 176 |
} |
| 177 |
/* split box */ |
| 178 |
*tree = split(box); |
| 179 |
bcopy(box, kb, sizeof(kb)); |
| 180 |
/* do left (lesser) branch */ |
| 181 |
kb[prim(*tree)][1] = part(*tree); |
| 182 |
cut(tree+(1<<level), level+1, kb, c0, (c0+c1)>>1); |
| 183 |
/* do right branch */ |
| 184 |
kb[prim(*tree)][0] = part(*tree); |
| 185 |
kb[prim(*tree)][1] = box[prim(*tree)][1]; |
| 186 |
cut(tree+(1<<(level+1)), level+1, kb, (c0+c1)>>1, c1); |
| 187 |
} |
| 188 |
|
| 189 |
|
| 190 |
static int |
| 191 |
split(box) /* find median cut for box */ |
| 192 |
register int box[3][2]; |
| 193 |
{ |
| 194 |
#define c0 r |
| 195 |
register int r, g, b; |
| 196 |
int pri; |
| 197 |
int t[HMAX], med; |
| 198 |
/* find dominant axis */ |
| 199 |
pri = RED; |
| 200 |
if (box[GRN][1]-box[GRN][0] > box[pri][1]-box[pri][0]) |
| 201 |
pri = GRN; |
| 202 |
if (box[BLU][1]-box[BLU][0] > box[pri][1]-box[pri][0]) |
| 203 |
pri = BLU; |
| 204 |
/* sum histogram over box */ |
| 205 |
med = 0; |
| 206 |
switch (pri) { |
| 207 |
case RED: |
| 208 |
for (r = box[RED][0]; r < box[RED][1]; r++) { |
| 209 |
t[r] = 0; |
| 210 |
for (g = box[GRN][0]; g < box[GRN][1]; g++) |
| 211 |
for (b = box[BLU][0]; b < box[BLU][1]; b++) |
| 212 |
t[r] += histo[r][g][b]; |
| 213 |
med += t[r]; |
| 214 |
} |
| 215 |
break; |
| 216 |
case GRN: |
| 217 |
for (g = box[GRN][0]; g < box[GRN][1]; g++) { |
| 218 |
t[g] = 0; |
| 219 |
for (b = box[BLU][0]; b < box[BLU][1]; b++) |
| 220 |
for (r = box[RED][0]; r < box[RED][1]; r++) |
| 221 |
t[g] += histo[r][g][b]; |
| 222 |
med += t[g]; |
| 223 |
} |
| 224 |
break; |
| 225 |
case BLU: |
| 226 |
for (b = box[BLU][0]; b < box[BLU][1]; b++) { |
| 227 |
t[b] = 0; |
| 228 |
for (r = box[RED][0]; r < box[RED][1]; r++) |
| 229 |
for (g = box[GRN][0]; g < box[GRN][1]; g++) |
| 230 |
t[b] += histo[r][g][b]; |
| 231 |
med += t[b]; |
| 232 |
} |
| 233 |
break; |
| 234 |
} |
| 235 |
if (med < MINSAMP) /* if too sparse, split at midpoint */ |
| 236 |
return(set_branch(pri,(box[pri][0]+box[pri][1])>>1)); |
| 237 |
/* find median position */ |
| 238 |
med >>= 1; |
| 239 |
for (c0 = box[pri][0]; med > 0; c0++) |
| 240 |
med -= t[c0]; |
| 241 |
if (c0 > (box[pri][0]+box[pri][1])>>1) /* if past the midpoint */ |
| 242 |
c0--; /* part left of median */ |
| 243 |
return(set_branch(pri,c0)); |
| 244 |
#undef c0 |
| 245 |
} |
