src/rt/colortab.c

#ifndef lint
static const char       RCSid[] = "$Id$";
#endif
/*
 * colortab.c - allocate and control dynamic color table.
 *
 *      We start off with a uniform partition of color space.
 *      As pixels are sent to the frame buffer, a histogram is built.
 *      When a new color table is requested, the histogram is used
 *      to make a pseudo-optimal partition, after which the
 *      histogram is cleared.  This algorithm
 *      performs only as well as the next drawing's color
 *      distribution is correlated to the last.
 *
 *  External symbols declared in drvier.h
 */

#include "copyright.h"

#include "standard.h"

#include "color.h"
                                /* histogram resolution */
#define NRED            24
#define NGRN            32
#define NBLU            16
#define HMAX            NGRN
                                /* minimum box count for adaptive partition */
#define MINSAMP         7
                                /* maximum distance^2 before color reassign */
#define MAXDST2         12
                                /* map a color */
#define map_col(c,p)    clrmap[p][ colval(c,p)<1. ? \
                                (int)(colval(c,p)*256.) : 255 ]
                                /* color partition tree */
#define CNODE           short
#define set_branch(p,c) ((c)<<2|(p))
#define set_pval(pv)    ((pv)<<2|3)
#define is_branch(cn)   (((cn)&3)!=3)
#define is_pval(cn)     (((cn)&3)==3)
#define part(cn)        ((cn)>>2)
#define prim(cn)        ((cn)&3)
#define pval(cn)        ((cn)>>2)
                                /* our color table */
static struct tabent {
        long    sum[3];         /* sum of colors using this entry */
        int     n;              /* number of colors */
        BYTE    ent[3];         /* current table value */
}       *clrtab = NULL;
                                /* color cube partition */
static CNODE    *ctree = NULL;
                                /* our color correction map */
static BYTE     clrmap[3][256];
                                /* histogram of colors used */
static unsigned short   histo[NRED][NGRN][NBLU];
                                /* initial color cube boundary */
static int      CLRCUBE[3][2] = {{0,NRED},{0,NGRN},{0,NBLU}};

static int      split();
static void     cut();


int
new_ctab(ncolors)               /* start new color table with max ncolors */
int     ncolors;
{
        int     treesize;

        if (ncolors < 1)
                return(0);
                                /* free old tables */
        if (clrtab != NULL)
                free((void *)clrtab);
        if (ctree != NULL)
                free((void *)ctree);
                                /* get new tables */
        for (treesize = 1; treesize < ncolors; treesize <<= 1)
                ;
        treesize <<= 1;
        clrtab = (struct tabent *)calloc(ncolors, sizeof(struct tabent));
        ctree = (CNODE *)malloc(treesize*sizeof(CNODE));
        if (clrtab == NULL || ctree == NULL)
                return(0);
                                /* partition color space */
        cut(ctree, 0, CLRCUBE, 0, ncolors);
                                /* clear histogram */
        bzero((char *)histo, sizeof(histo));
                                /* return number of colors used */
        return(ncolors);
}


int
get_pixel(col, set_pixel)       /* get pixel for color */
COLOR   col;
void    (*set_pixel)();
{
        int     r, g, b;
        int     cv[3];
        register CNODE  *tp;
        register int    h;
                                                /* map color */
        r = map_col(col,RED);
        g = map_col(col,GRN);
        b = map_col(col,BLU);
                                                /* reduce resolution */
        cv[RED] = (r*NRED)>>8;
        cv[GRN] = (g*NGRN)>>8;
        cv[BLU] = (b*NBLU)>>8;
                                                /* add to histogram */
        histo[cv[RED]][cv[GRN]][cv[BLU]]++;
                                                /* find pixel in tree */
        for (tp = ctree, h = 0; is_branch(*tp); h++)
                if (cv[prim(*tp)] < part(*tp))
                        tp += 1<<h;             /* left branch */
                else
                        tp += 1<<(h+1);         /* right branch */
        h = pval(*tp);
                                                /* add to color table */
        clrtab[h].sum[RED] += r;
        clrtab[h].sum[GRN] += g;
        clrtab[h].sum[BLU] += b;
        clrtab[h].n++;
                                        /* recompute average */
        r = clrtab[h].sum[RED] / clrtab[h].n;
        g = clrtab[h].sum[GRN] / clrtab[h].n;
        b = clrtab[h].sum[BLU] / clrtab[h].n;
                                        /* check for movement */
        if (clrtab[h].n == 1 ||
                        (r-clrtab[h].ent[RED])*(r-clrtab[h].ent[RED]) +
                        (g-clrtab[h].ent[GRN])*(g-clrtab[h].ent[GRN]) +
                        (b-clrtab[h].ent[BLU])*(b-clrtab[h].ent[BLU]) > MAXDST2) {
                clrtab[h].ent[RED] = r;
                clrtab[h].ent[GRN] = g; /* reassign pixel */
                clrtab[h].ent[BLU] = b;
#ifdef DEBUG
                sprintf(errmsg, "pixel %d = (%d,%d,%d) (%d refs)\n",
                                h, r, g, b, clrtab[h].n);
                eputs(errmsg);
#endif
                (*set_pixel)(h, r, g, b);
        }
        return(h);                              /* return pixel value */
}


void
make_gmap(gam)                  /* make gamma correction map */
double  gam;
{
        register int    i;
        
        for (i = 0; i < 256; i++)
                clrmap[RED][i] =
                clrmap[GRN][i] =
                clrmap[BLU][i] = 256.0 * pow((i+0.5)/256.0, 1.0/gam);
}


void
set_cmap(rmap, gmap, bmap)      /* set custom color correction map */
BYTE    *rmap, *gmap, *bmap;
{
        bcopy((char *)rmap, (char *)clrmap[RED], 256);
        bcopy((char *)gmap, (char *)clrmap[GRN], 256);
        bcopy((char *)bmap, (char *)clrmap[BLU], 256);
}


void
map_color(rgb, col)             /* map a color to a byte triplet */
BYTE    rgb[3];
COLOR   col;
{
        rgb[RED] = map_col(col,RED);
        rgb[GRN] = map_col(col,GRN);
        rgb[BLU] = map_col(col,BLU);
}


static void
cut(tree, level, box, c0, c1)           /* partition color space */
register CNODE  *tree;
int     level;
register int    box[3][2];
int     c0, c1;
{
        int     kb[3][2];
        
        if (c1-c0 <= 1) {               /* assign pixel */
                *tree = set_pval(c0);
                return;
        }
                                        /* split box */
        *tree = split(box);
        bcopy((char *)box, (char *)kb, sizeof(kb));
                                                /* do left (lesser) branch */
        kb[prim(*tree)][1] = part(*tree);
        cut(tree+(1<<level), level+1, kb, c0, (c0+c1)>>1);
                                                /* do right branch */
        kb[prim(*tree)][0] = part(*tree);
        kb[prim(*tree)][1] = box[prim(*tree)][1];
        cut(tree+(1<<(level+1)), level+1, kb, (c0+c1)>>1, c1);
}


static int
split(box)                              /* find median cut for box */
register int    box[3][2];
{
#define c0      r
        register int    r, g, b;
        int     pri;
        long    t[HMAX], med;
                                        /* find dominant axis */
        pri = RED;
        if (box[GRN][1]-box[GRN][0] > box[pri][1]-box[pri][0])
                pri = GRN;
        if (box[BLU][1]-box[BLU][0] > box[pri][1]-box[pri][0])
                pri = BLU;
                                        /* sum histogram over box */
        med = 0;
        switch (pri) {
        case RED:
                for (r = box[RED][0]; r < box[RED][1]; r++) {
                        t[r] = 0;
                        for (g = box[GRN][0]; g < box[GRN][1]; g++)
                                for (b = box[BLU][0]; b < box[BLU][1]; b++)
                                        t[r] += histo[r][g][b];
                        med += t[r];
                }
                break;
        case GRN:
                for (g = box[GRN][0]; g < box[GRN][1]; g++) {
                        t[g] = 0;
                        for (b = box[BLU][0]; b < box[BLU][1]; b++)
                                for (r = box[RED][0]; r < box[RED][1]; r++)
                                        t[g] += histo[r][g][b];
                        med += t[g];
                }
                break;
        case BLU:
                for (b = box[BLU][0]; b < box[BLU][1]; b++) {
                        t[b] = 0;
                        for (r = box[RED][0]; r < box[RED][1]; r++)
                                for (g = box[GRN][0]; g < box[GRN][1]; g++)
                                        t[b] += histo[r][g][b];
                        med += t[b];
                }
                break;
        }
        if (med < MINSAMP)              /* if too sparse, split at midpoint */
                return(set_branch(pri,(box[pri][0]+box[pri][1])>>1));
                                        /* find median position */
        med >>= 1;
        for (c0 = box[pri][0]; med > 0; c0++)
                med -= t[c0];
        if (c0 > (box[pri][0]+box[pri][1])>>1)  /* if past the midpoint */
                c0--;                           /* part left of median */
        return(set_branch(pri,c0));
#undef c0
}
Revision:	2.6
Committed:	Tue Feb 25 02:47:22 2003 UTC (21 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rad3R5
Changes since 2.5:	+1 -56 lines
Log Message:	Replaced inline copyright notice with #include "copyright.h"
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.5	static const char RCSid[] = "$Id$";
3	greg	1.1	#endif
4			/*
5			* colortab.c - allocate and control dynamic color table.
6			*
7			* We start off with a uniform partition of color space.
8			* As pixels are sent to the frame buffer, a histogram is built.
9			* When a new color table is requested, the histogram is used
10			* to make a pseudo-optimal partition, after which the
11			* histogram is cleared. This algorithm
12			* performs only as well as the next drawing's color
13			* distribution is correlated to the last.
14	greg	2.5	*
15			* External symbols declared in drvier.h
16			*/
17
18	greg	2.6	#include "copyright.h"
19	greg	1.1
20	greg	1.15	#include "standard.h"
21
22	greg	1.1	#include "color.h"
23			/* histogram resolution */
24	greg	1.3	#define NRED 24
25	greg	1.1	#define NGRN 32
26	greg	1.3	#define NBLU 16
27	greg	1.1	#define HMAX NGRN
28			/* minimum box count for adaptive partition */
29			#define MINSAMP 7
30	greg	1.3	/* maximum distance^2 before color reassign */
31	greg	1.5	#define MAXDST2 12
32	greg	1.1	/* map a color */
33	greg	1.4	#define map_col(c,p) clrmap[p][ colval(c,p)<1. ? \
34			(int)(colval(c,p)*256.) : 255 ]
35	greg	1.1	/* color partition tree */
36			#define CNODE short
37	greg	2.2	#define set_branch(p,c) ((c)<<2\|(p))
38	greg	1.1	#define set_pval(pv) ((pv)<<2\|3)
39	greg	1.7	#define is_branch(cn) (((cn)&3)!=3)
40	greg	1.1	#define is_pval(cn) (((cn)&3)==3)
41			#define part(cn) ((cn)>>2)
42			#define prim(cn) ((cn)&3)
43			#define pval(cn) ((cn)>>2)
44			/* our color table */
45	greg	1.6	static struct tabent {
46	greg	1.3	long sum[3]; /* sum of colors using this entry */
47	greg	1.15	int n; /* number of colors */
48			BYTE ent[3]; /* current table value */
49	greg	1.8	} *clrtab = NULL;
50			/* color cube partition */
51			static CNODE *ctree = NULL;
52	greg	1.1	/* our color correction map */
53	greg	1.4	static BYTE clrmap[3][256];
54	greg	1.1	/* histogram of colors used */
55	greg	1.9	static unsigned short histo[NRED][NGRN][NBLU];
56	greg	1.8	/* initial color cube boundary */
57	greg	2.3	static int CLRCUBE[3][2] = {{0,NRED},{0,NGRN},{0,NBLU}};
58
59	greg	2.5	static int split();
60			static void cut();
61	greg	1.1
62
63	greg	1.3	int
64	greg	1.4	new_ctab(ncolors) /* start new color table with max ncolors */
65	greg	1.1	int ncolors;
66			{
67	greg	1.8	int treesize;
68
69	greg	1.6	if (ncolors < 1)
70	greg	1.3	return(0);
71	greg	1.8	/* free old tables */
72			if (clrtab != NULL)
73	greg	2.5	free((void *)clrtab);
74	greg	1.8	if (ctree != NULL)
75	greg	2.5	free((void *)ctree);
76	greg	1.8	/* get new tables */
77			for (treesize = 1; treesize < ncolors; treesize <<= 1)
78			;
79			treesize <<= 1;
80			clrtab = (struct tabent *)calloc(ncolors, sizeof(struct tabent));
81			ctree = (CNODE )malloc(treesizesizeof(CNODE));
82			if (clrtab == NULL \|\| ctree == NULL)
83			return(0);
84	greg	1.3	/* partition color space */
85	greg	1.7	cut(ctree, 0, CLRCUBE, 0, ncolors);
86	greg	1.1	/* clear histogram */
87	greg	1.11	bzero((char *)histo, sizeof(histo));
88	greg	1.3	/* return number of colors used */
89			return(ncolors);
90	greg	1.1	}
91
92
93			int
94	greg	1.4	get_pixel(col, set_pixel) /* get pixel for color */
95	greg	1.1	COLOR col;
96	greg	2.5	void (*set_pixel)();
97	greg	1.1	{
98	greg	1.3	int r, g, b;
99	greg	1.1	int cv[3];
100	greg	1.10	register CNODE *tp;
101	greg	1.1	register int h;
102	greg	1.3	/* map color */
103			r = map_col(col,RED);
104			g = map_col(col,GRN);
105			b = map_col(col,BLU);
106			/* reduce resolution */
107			cv[RED] = (r*NRED)>>8;
108			cv[GRN] = (g*NGRN)>>8;
109			cv[BLU] = (b*NBLU)>>8;
110			/* add to histogram */
111	greg	1.1	histo[cv[RED]][cv[GRN]][cv[BLU]]++;
112	greg	1.3	/* find pixel in tree */
113	greg	1.10	for (tp = ctree, h = 0; is_branch(*tp); h++)
114			if (cv[prim(tp)] < part(tp))
115			tp += 1<<h; /* left branch */
116	greg	1.1	else
117	greg	1.15	tp += 1<<(h+1); /* right branch */
118	greg	1.10	h = pval(*tp);
119	greg	1.3	/* add to color table */
120	greg	1.10	clrtab[h].sum[RED] += r;
121			clrtab[h].sum[GRN] += g;
122			clrtab[h].sum[BLU] += b;
123			clrtab[h].n++;
124	greg	1.3	/* recompute average */
125	greg	1.10	r = clrtab[h].sum[RED] / clrtab[h].n;
126			g = clrtab[h].sum[GRN] / clrtab[h].n;
127			b = clrtab[h].sum[BLU] / clrtab[h].n;
128	greg	1.3	/* check for movement */
129	greg	1.10	if (clrtab[h].n == 1 \|\|
130			(r-clrtab[h].ent[RED])*(r-clrtab[h].ent[RED]) +
131			(g-clrtab[h].ent[GRN])*(g-clrtab[h].ent[GRN]) +
132			(b-clrtab[h].ent[BLU])*(b-clrtab[h].ent[BLU]) > MAXDST2) {
133			clrtab[h].ent[RED] = r;
134	greg	2.2	clrtab[h].ent[GRN] = g; /* reassign pixel */
135	greg	1.10	clrtab[h].ent[BLU] = b;
136	greg	1.12	#ifdef DEBUG
137			sprintf(errmsg, "pixel %d = (%d,%d,%d) (%d refs)\n",
138	greg	1.10	h, r, g, b, clrtab[h].n);
139	greg	1.12	eputs(errmsg);
140	greg	1.1	#endif
141	greg	1.3	(*set_pixel)(h, r, g, b);
142			}
143			return(h); /* return pixel value */
144	greg	1.1	}
145
146
147	greg	2.5	void
148	greg	1.4	make_gmap(gam) /* make gamma correction map */
149	greg	2.2	double gam;
150	greg	1.1	{
151			register int i;
152
153	greg	1.4	for (i = 0; i < 256; i++)
154			clrmap[RED][i] =
155			clrmap[GRN][i] =
156	greg	1.15	clrmap[BLU][i] = 256.0 * pow((i+0.5)/256.0, 1.0/gam);
157	greg	1.4	}
158
159
160	greg	2.5	void
161	greg	1.4	set_cmap(rmap, gmap, bmap) /* set custom color correction map */
162			BYTE rmap, gmap, *bmap;
163			{
164	greg	1.11	bcopy((char )rmap, (char )clrmap[RED], 256);
165			bcopy((char )gmap, (char )clrmap[GRN], 256);
166			bcopy((char )bmap, (char )clrmap[BLU], 256);
167	greg	1.1	}
168
169
170	greg	2.5	void
171	greg	1.13	map_color(rgb, col) /* map a color to a byte triplet */
172			BYTE rgb[3];
173			COLOR col;
174			{
175			rgb[RED] = map_col(col,RED);
176			rgb[GRN] = map_col(col,GRN);
177			rgb[BLU] = map_col(col,BLU);
178			}
179
180
181	greg	2.5	static void
182	greg	1.7	cut(tree, level, box, c0, c1) /* partition color space */
183	greg	1.1	register CNODE *tree;
184	greg	1.7	int level;
185	greg	1.1	register int box[3][2];
186			int c0, c1;
187			{
188			int kb[3][2];
189
190	greg	1.3	if (c1-c0 <= 1) { /* assign pixel */
191	greg	1.1	*tree = set_pval(c0);
192			return;
193			}
194			/* split box */
195			*tree = split(box);
196	greg	1.11	bcopy((char )box, (char )kb, sizeof(kb));
197	greg	1.3	/* do left (lesser) branch */
198	greg	1.1	kb[prim(tree)][1] = part(tree);
199	greg	1.7	cut(tree+(1<<level), level+1, kb, c0, (c0+c1)>>1);
200	greg	1.3	/* do right branch */
201	greg	1.1	kb[prim(tree)][0] = part(tree);
202			kb[prim(tree)][1] = box[prim(tree)][1];
203	greg	1.7	cut(tree+(1<<(level+1)), level+1, kb, (c0+c1)>>1, c1);
204	greg	1.1	}
205
206
207			static int
208			split(box) /* find median cut for box */
209			register int box[3][2];
210			{
211			#define c0 r
212			register int r, g, b;
213			int pri;
214	greg	2.4	long t[HMAX], med;
215	greg	1.1	/* find dominant axis */
216			pri = RED;
217			if (box[GRN][1]-box[GRN][0] > box[pri][1]-box[pri][0])
218			pri = GRN;
219			if (box[BLU][1]-box[BLU][0] > box[pri][1]-box[pri][0])
220			pri = BLU;
221			/* sum histogram over box */
222			med = 0;
223			switch (pri) {
224			case RED:
225			for (r = box[RED][0]; r < box[RED][1]; r++) {
226			t[r] = 0;
227			for (g = box[GRN][0]; g < box[GRN][1]; g++)
228			for (b = box[BLU][0]; b < box[BLU][1]; b++)
229			t[r] += histo[r][g][b];
230			med += t[r];
231			}
232			break;
233			case GRN:
234			for (g = box[GRN][0]; g < box[GRN][1]; g++) {
235			t[g] = 0;
236			for (b = box[BLU][0]; b < box[BLU][1]; b++)
237			for (r = box[RED][0]; r < box[RED][1]; r++)
238			t[g] += histo[r][g][b];
239			med += t[g];
240			}
241			break;
242			case BLU:
243			for (b = box[BLU][0]; b < box[BLU][1]; b++) {
244			t[b] = 0;
245			for (r = box[RED][0]; r < box[RED][1]; r++)
246			for (g = box[GRN][0]; g < box[GRN][1]; g++)
247			t[b] += histo[r][g][b];
248			med += t[b];
249			}
250			break;
251			}
252			if (med < MINSAMP) /* if too sparse, split at midpoint */
253			return(set_branch(pri,(box[pri][0]+box[pri][1])>>1));
254			/* find median position */
255			med >>= 1;
256			for (c0 = box[pri][0]; med > 0; c0++)
257			med -= t[c0];
258			if (c0 > (box[pri][0]+box[pri][1])>>1) /* if past the midpoint */
259			c0--; /* part left of median */
260			return(set_branch(pri,c0));
261			#undef c0
262			}