src/rt/colortab.c

#ifndef lint
static const char       RCSid[] = "$Id: colortab.c,v 2.7 2003/05/13 17:58:33 greg Exp $";
#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 <string.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 */
        memset((void *)histo, '\0', 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;
{
        memcpy((void *)clrmap[RED], (void *)rmap, 256);
        memcpy((void *)clrmap[GRN], (void *)gmap, 256);
        memcpy((void *)clrmap[BLU], (void *)bmap, 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);
        memcpy((void *)kb, (void *)box, 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:	2.8
Committed:	Mon Jun 30 14:59:12 2003 UTC (20 years, 10 months ago) by schorsch
Content type:	text/plain
Branch:	MAIN
Changes since 2.7:	+9 -7 lines
Log Message:	Replaced most outdated BSD function calls with their posix equivalents, and cleaned up a few other platform dependencies.
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	schorsch	2.8	static const char RCSid[] = "$Id: colortab.c,v 2.7 2003/05/13 17:58:33 greg Exp $";
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	schorsch	2.8	#include <string.h>
21
22	greg	1.15	#include "standard.h"
23	schorsch	2.8	#include "color.h"
24	greg	1.15
25	greg	1.1	/* histogram resolution */
26	greg	1.3	#define NRED 24
27	greg	1.1	#define NGRN 32
28	greg	1.3	#define NBLU 16
29	greg	1.1	#define HMAX NGRN
30			/* minimum box count for adaptive partition */
31			#define MINSAMP 7
32	greg	1.3	/* maximum distance^2 before color reassign */
33	greg	1.5	#define MAXDST2 12
34	greg	1.1	/* map a color */
35	greg	1.4	#define map_col(c,p) clrmap[p][ colval(c,p)<1. ? \
36			(int)(colval(c,p)*256.) : 255 ]
37	greg	1.1	/* color partition tree */
38			#define CNODE short
39	greg	2.2	#define set_branch(p,c) ((c)<<2\|(p))
40	greg	1.1	#define set_pval(pv) ((pv)<<2\|3)
41	greg	1.7	#define is_branch(cn) (((cn)&3)!=3)
42	greg	1.1	#define is_pval(cn) (((cn)&3)==3)
43			#define part(cn) ((cn)>>2)
44			#define prim(cn) ((cn)&3)
45			#define pval(cn) ((cn)>>2)
46			/* our color table */
47	greg	1.6	static struct tabent {
48	greg	1.3	long sum[3]; /* sum of colors using this entry */
49	greg	1.15	int n; /* number of colors */
50			BYTE ent[3]; /* current table value */
51	greg	1.8	} *clrtab = NULL;
52			/* color cube partition */
53			static CNODE *ctree = NULL;
54	greg	1.1	/* our color correction map */
55	greg	1.4	static BYTE clrmap[3][256];
56	greg	1.1	/* histogram of colors used */
57	greg	1.9	static unsigned short histo[NRED][NGRN][NBLU];
58	greg	1.8	/* initial color cube boundary */
59	greg	2.3	static int CLRCUBE[3][2] = {{0,NRED},{0,NGRN},{0,NBLU}};
60
61	greg	2.5	static int split();
62			static void cut();
63	greg	1.1
64
65	greg	1.3	int
66	greg	1.4	new_ctab(ncolors) /* start new color table with max ncolors */
67	greg	1.1	int ncolors;
68			{
69	greg	1.8	int treesize;
70
71	greg	1.6	if (ncolors < 1)
72	greg	1.3	return(0);
73	greg	1.8	/* free old tables */
74			if (clrtab != NULL)
75	greg	2.5	free((void *)clrtab);
76	greg	1.8	if (ctree != NULL)
77	greg	2.5	free((void *)ctree);
78	greg	1.8	/* get new tables */
79			for (treesize = 1; treesize < ncolors; treesize <<= 1)
80			;
81			treesize <<= 1;
82			clrtab = (struct tabent *)calloc(ncolors, sizeof(struct tabent));
83			ctree = (CNODE )malloc(treesizesizeof(CNODE));
84			if (clrtab == NULL \|\| ctree == NULL)
85			return(0);
86	greg	1.3	/* partition color space */
87	greg	1.7	cut(ctree, 0, CLRCUBE, 0, ncolors);
88	greg	1.1	/* clear histogram */
89	schorsch	2.8	memset((void *)histo, '\0', sizeof(histo));
90	greg	1.3	/* return number of colors used */
91			return(ncolors);
92	greg	1.1	}
93
94
95			int
96	greg	1.4	get_pixel(col, set_pixel) /* get pixel for color */
97	greg	1.1	COLOR col;
98	greg	2.5	void (*set_pixel)();
99	greg	1.1	{
100	greg	1.3	int r, g, b;
101	greg	1.1	int cv[3];
102	greg	1.10	register CNODE *tp;
103	greg	1.1	register int h;
104	greg	1.3	/* map color */
105			r = map_col(col,RED);
106			g = map_col(col,GRN);
107			b = map_col(col,BLU);
108			/* reduce resolution */
109			cv[RED] = (r*NRED)>>8;
110			cv[GRN] = (g*NGRN)>>8;
111			cv[BLU] = (b*NBLU)>>8;
112			/* add to histogram */
113	greg	1.1	histo[cv[RED]][cv[GRN]][cv[BLU]]++;
114	greg	1.3	/* find pixel in tree */
115	greg	1.10	for (tp = ctree, h = 0; is_branch(*tp); h++)
116			if (cv[prim(tp)] < part(tp))
117			tp += 1<<h; /* left branch */
118	greg	1.1	else
119	greg	1.15	tp += 1<<(h+1); /* right branch */
120	greg	1.10	h = pval(*tp);
121	greg	1.3	/* add to color table */
122	greg	1.10	clrtab[h].sum[RED] += r;
123			clrtab[h].sum[GRN] += g;
124			clrtab[h].sum[BLU] += b;
125			clrtab[h].n++;
126	greg	1.3	/* recompute average */
127	greg	1.10	r = clrtab[h].sum[RED] / clrtab[h].n;
128			g = clrtab[h].sum[GRN] / clrtab[h].n;
129			b = clrtab[h].sum[BLU] / clrtab[h].n;
130	greg	1.3	/* check for movement */
131	greg	1.10	if (clrtab[h].n == 1 \|\|
132			(r-clrtab[h].ent[RED])*(r-clrtab[h].ent[RED]) +
133			(g-clrtab[h].ent[GRN])*(g-clrtab[h].ent[GRN]) +
134			(b-clrtab[h].ent[BLU])*(b-clrtab[h].ent[BLU]) > MAXDST2) {
135			clrtab[h].ent[RED] = r;
136	greg	2.2	clrtab[h].ent[GRN] = g; /* reassign pixel */
137	greg	1.10	clrtab[h].ent[BLU] = b;
138	greg	1.12	#ifdef DEBUG
139			sprintf(errmsg, "pixel %d = (%d,%d,%d) (%d refs)\n",
140	greg	1.10	h, r, g, b, clrtab[h].n);
141	greg	1.12	eputs(errmsg);
142	greg	1.1	#endif
143	greg	1.3	(*set_pixel)(h, r, g, b);
144			}
145			return(h); /* return pixel value */
146	greg	1.1	}
147
148
149	greg	2.5	void
150	greg	1.4	make_gmap(gam) /* make gamma correction map */
151	greg	2.2	double gam;
152	greg	1.1	{
153			register int i;
154
155	greg	1.4	for (i = 0; i < 256; i++)
156			clrmap[RED][i] =
157			clrmap[GRN][i] =
158	greg	1.15	clrmap[BLU][i] = 256.0 * pow((i+0.5)/256.0, 1.0/gam);
159	greg	1.4	}
160
161
162	greg	2.5	void
163	greg	1.4	set_cmap(rmap, gmap, bmap) /* set custom color correction map */
164			BYTE rmap, gmap, *bmap;
165			{
166	schorsch	2.8	memcpy((void )clrmap[RED], (void )rmap, 256);
167			memcpy((void )clrmap[GRN], (void )gmap, 256);
168			memcpy((void )clrmap[BLU], (void )bmap, 256);
169	greg	1.1	}
170
171
172	greg	2.5	void
173	greg	1.13	map_color(rgb, col) /* map a color to a byte triplet */
174			BYTE rgb[3];
175			COLOR col;
176			{
177			rgb[RED] = map_col(col,RED);
178			rgb[GRN] = map_col(col,GRN);
179			rgb[BLU] = map_col(col,BLU);
180			}
181
182
183	greg	2.5	static void
184	greg	1.7	cut(tree, level, box, c0, c1) /* partition color space */
185	greg	1.1	register CNODE *tree;
186	greg	1.7	int level;
187	greg	1.1	register int box[3][2];
188			int c0, c1;
189			{
190			int kb[3][2];
191
192	greg	1.3	if (c1-c0 <= 1) { /* assign pixel */
193	greg	1.1	*tree = set_pval(c0);
194			return;
195			}
196			/* split box */
197			*tree = split(box);
198	schorsch	2.8	memcpy((void )kb, (void )box, sizeof(kb));
199	greg	1.3	/* do left (lesser) branch */
200	greg	1.1	kb[prim(tree)][1] = part(tree);
201	greg	1.7	cut(tree+(1<<level), level+1, kb, c0, (c0+c1)>>1);
202	greg	1.3	/* do right branch */
203	greg	1.1	kb[prim(tree)][0] = part(tree);
204			kb[prim(tree)][1] = box[prim(tree)][1];
205	greg	1.7	cut(tree+(1<<(level+1)), level+1, kb, (c0+c1)>>1, c1);
206	greg	1.1	}
207
208
209			static int
210			split(box) /* find median cut for box */
211			register int box[3][2];
212			{
213			#define c0 r
214			register int r, g, b;
215			int pri;
216	greg	2.4	long t[HMAX], med;
217	greg	1.1	/* find dominant axis */
218			pri = RED;
219			if (box[GRN][1]-box[GRN][0] > box[pri][1]-box[pri][0])
220			pri = GRN;
221			if (box[BLU][1]-box[BLU][0] > box[pri][1]-box[pri][0])
222			pri = BLU;
223			/* sum histogram over box */
224			med = 0;
225			switch (pri) {
226			case RED:
227			for (r = box[RED][0]; r < box[RED][1]; r++) {
228			t[r] = 0;
229			for (g = box[GRN][0]; g < box[GRN][1]; g++)
230			for (b = box[BLU][0]; b < box[BLU][1]; b++)
231			t[r] += histo[r][g][b];
232			med += t[r];
233			}
234			break;
235			case GRN:
236			for (g = box[GRN][0]; g < box[GRN][1]; g++) {
237			t[g] = 0;
238			for (b = box[BLU][0]; b < box[BLU][1]; b++)
239			for (r = box[RED][0]; r < box[RED][1]; r++)
240			t[g] += histo[r][g][b];
241			med += t[g];
242			}
243			break;
244			case BLU:
245			for (b = box[BLU][0]; b < box[BLU][1]; b++) {
246			t[b] = 0;
247			for (r = box[RED][0]; r < box[RED][1]; r++)
248			for (g = box[GRN][0]; g < box[GRN][1]; g++)
249			t[b] += histo[r][g][b];
250			med += t[b];
251			}
252			break;
253			}
254			if (med < MINSAMP) /* if too sparse, split at midpoint */
255			return(set_branch(pri,(box[pri][0]+box[pri][1])>>1));
256			/* find median position */
257			med >>= 1;
258			for (c0 = box[pri][0]; med > 0; c0++)
259			med -= t[c0];
260			if (c0 > (box[pri][0]+box[pri][1])>>1) /* if past the midpoint */
261			c0--; /* part left of median */
262			return(set_branch(pri,c0));
263			#undef c0
264			}