src/hd/rhd_ctab.c

/* Copyright (c) 1997 Silicon Graphics, Inc. */

#ifndef lint
static char SCCSid[] = "$SunId$ SGI";
#endif

/*
 * 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.
 *
 *      This module is essentially identical to src/rt/colortab.c,
 *      except there is no color mapping, since the tm library is used.
 */

#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
                                /* 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;
                                /* 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(), 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((char *)clrtab);
        if (ctree != NULL)
                free((char *)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(rgb, set_pixel)       /* get pixel for color */
BYTE    rgb[3];
int     (*set_pixel)();
{
        extern char     errmsg[];
        int     r, g, b;
        int     cv[3];
        register CNODE  *tp;
        register int    h;
                                                /* get desired color */
        r = rgb[RED];
        g = rgb[GRN];
        b = rgb[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 */
}


static
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:	3.1
Committed:	Wed Nov 19 18:01:03 1997 UTC (26 years, 5 months ago) by gregl
Content type:	text/plain
Branch:	MAIN
Log Message:	Initial revision
#	User	Rev	Content
1	gregl	3.1	/* Copyright (c) 1997 Silicon Graphics, Inc. */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ SGI";
5			#endif
6
7			/*
8			* 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			* This module is essentially identical to src/rt/colortab.c,
19			* except there is no color mapping, since the tm library is used.
20			*/
21
22			#include "standard.h"
23			#include "color.h"
24			/* histogram resolution */
25			#define NRED 24
26			#define NGRN 32
27			#define NBLU 16
28			#define HMAX NGRN
29			/* minimum box count for adaptive partition */
30			#define MINSAMP 7
31			/* maximum distance^2 before color reassign */
32			#define MAXDST2 12
33			/* color partition tree */
34			#define CNODE short
35			#define set_branch(p,c) ((c)<<2\|(p))
36			#define set_pval(pv) ((pv)<<2\|3)
37			#define is_branch(cn) (((cn)&3)!=3)
38			#define is_pval(cn) (((cn)&3)==3)
39			#define part(cn) ((cn)>>2)
40			#define prim(cn) ((cn)&3)
41			#define pval(cn) ((cn)>>2)
42			/* our color table */
43			static struct tabent {
44			long sum[3]; /* sum of colors using this entry */
45			int n; /* number of colors */
46			BYTE ent[3]; /* current table value */
47			} *clrtab = NULL;
48			/* color cube partition */
49			static CNODE *ctree = NULL;
50			/* histogram of colors used */
51			static unsigned short histo[NRED][NGRN][NBLU];
52			/* initial color cube boundary */
53			static int CLRCUBE[3][2] = {{0,NRED},{0,NGRN},{0,NBLU}};
54
55			static int split(), cut();
56
57
58			int
59			new_ctab(ncolors) /* start new color table with max ncolors */
60			int ncolors;
61			{
62			int treesize;
63
64			if (ncolors < 1)
65			return(0);
66			/* free old tables */
67			if (clrtab != NULL)
68			free((char *)clrtab);
69			if (ctree != NULL)
70			free((char *)ctree);
71			/* get new tables */
72			for (treesize = 1; treesize < ncolors; treesize <<= 1)
73			;
74			treesize <<= 1;
75			clrtab = (struct tabent *)calloc(ncolors, sizeof(struct tabent));
76			ctree = (CNODE )malloc(treesizesizeof(CNODE));
77			if (clrtab == NULL \|\| ctree == NULL)
78			return(0);
79			/* partition color space */
80			cut(ctree, 0, CLRCUBE, 0, ncolors);
81			/* clear histogram */
82			bzero((char *)histo, sizeof(histo));
83			/* return number of colors used */
84			return(ncolors);
85			}
86
87
88			int
89			get_pixel(rgb, set_pixel) /* get pixel for color */
90			BYTE rgb[3];
91			int (*set_pixel)();
92			{
93			extern char errmsg[];
94			int r, g, b;
95			int cv[3];
96			register CNODE *tp;
97			register int h;
98			/* get desired color */
99			r = rgb[RED];
100			g = rgb[GRN];
101			b = rgb[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 DEBUG
133			sprintf(errmsg, "pixel %d = (%d,%d,%d) (%d refs)\n",
134			h, r, g, b, clrtab[h].n);
135			eputs(errmsg);
136			#endif
137			(*set_pixel)(h, r, g, b);
138			}
139			return(h); /* return pixel value */
140			}
141
142
143			static
144			cut(tree, level, box, c0, c1) /* partition color space */
145			register CNODE *tree;
146			int level;
147			register int box[3][2];
148			int c0, c1;
149			{
150			int kb[3][2];
151
152			if (c1-c0 <= 1) { /* assign pixel */
153			*tree = set_pval(c0);
154			return;
155			}
156			/* split box */
157			*tree = split(box);
158			bcopy((char )box, (char )kb, sizeof(kb));
159			/* do left (lesser) branch */
160			kb[prim(tree)][1] = part(tree);
161			cut(tree+(1<<level), level+1, kb, c0, (c0+c1)>>1);
162			/* do right branch */
163			kb[prim(tree)][0] = part(tree);
164			kb[prim(tree)][1] = box[prim(tree)][1];
165			cut(tree+(1<<(level+1)), level+1, kb, (c0+c1)>>1, c1);
166			}
167
168
169			static int
170			split(box) /* find median cut for box */
171			register int box[3][2];
172			{
173			#define c0 r
174			register int r, g, b;
175			int pri;
176			long t[HMAX], med;
177			/* find dominant axis */
178			pri = RED;
179			if (box[GRN][1]-box[GRN][0] > box[pri][1]-box[pri][0])
180			pri = GRN;
181			if (box[BLU][1]-box[BLU][0] > box[pri][1]-box[pri][0])
182			pri = BLU;
183			/* sum histogram over box */
184			med = 0;
185			switch (pri) {
186			case RED:
187			for (r = box[RED][0]; r < box[RED][1]; r++) {
188			t[r] = 0;
189			for (g = box[GRN][0]; g < box[GRN][1]; g++)
190			for (b = box[BLU][0]; b < box[BLU][1]; b++)
191			t[r] += histo[r][g][b];
192			med += t[r];
193			}
194			break;
195			case GRN:
196			for (g = box[GRN][0]; g < box[GRN][1]; g++) {
197			t[g] = 0;
198			for (b = box[BLU][0]; b < box[BLU][1]; b++)
199			for (r = box[RED][0]; r < box[RED][1]; r++)
200			t[g] += histo[r][g][b];
201			med += t[g];
202			}
203			break;
204			case BLU:
205			for (b = box[BLU][0]; b < box[BLU][1]; b++) {
206			t[b] = 0;
207			for (r = box[RED][0]; r < box[RED][1]; r++)
208			for (g = box[GRN][0]; g < box[GRN][1]; g++)
209			t[b] += histo[r][g][b];
210			med += t[b];
211			}
212			break;
213			}
214			if (med < MINSAMP) /* if too sparse, split at midpoint */
215			return(set_branch(pri,(box[pri][0]+box[pri][1])>>1));
216			/* find median position */
217			med >>= 1;
218			for (c0 = box[pri][0]; med > 0; c0++)
219			med -= t[c0];
220			if (c0 > (box[pri][0]+box[pri][1])>>1) /* if past the midpoint */
221			c0--; /* part left of median */
222			return(set_branch(pri,c0));
223			#undef c0
224			}