src/common/color.c

#ifndef lint
static const char       RCSid[] = "$Id: color.c,v 2.X in progress $";
#endif
/*
 *  color.c - routines for color calculations.
 *
 *  Externals declared in color.h
 */

#include "copyright.h"

#include  <stdio.h>
#include  <stdlib.h>
#include  <math.h>
#include  "color.h"

#ifdef getc_unlocked            /* avoid horrendous overhead of flockfile */
#undef getc
#undef putc
#undef ferror
#define getc    getc_unlocked
#define putc    putc_unlocked
#define ferror  ferror_unlocked
#endif

#define  MINELEN        8       /* minimum scanline length for encoding */
#define  MAXELEN        0x7fff  /* maximum scanline length for encoding */
#define  MINRUN         4       /* minimum run length */


int  CNDX[4] = {0,1,2,3};       /* RGBE indices for SCOLOR, SCOLR */
float  WLPART[4] = {780,588,480,380};   /* RGB wavelength limits+partitions (nm) */


int
setspectrsamp(                  /* assign spectral sampling, 1 if good, -1 if bad */
        int cn[4],              /* input cn[3]=nsamps */
        float wlpt[4]           /* input wlpt[0],wlpt[3]=extrema */
)
{
        static const float      PKWL[3] = {607, 553, 469};
        int                     i, j;

        if (cn[3] < 3)
                return(-1);             /* reject this */

        if (wlpt[0] < wlpt[3]) {
                float   tf = wlpt[0];
                wlpt[0] = wlpt[3]; wlpt[3] = tf;
        }
        if (wlpt[0] - wlpt[3] < 50.f)
                return(-1);             /* also reject */

        if (cn[3] > MAXCSAMP)
                cn[3] = MAXCSAMP;

        if ((wlpt[3] >= PKWL[2]) | (wlpt[0] <= PKWL[0])) {
                wlpt[1] = wlpt[0] + 0.333333f*(wlpt[3]-wlpt[0]);
                wlpt[2] = wlpt[0] + 0.666667f*(wlpt[3]-wlpt[0]);
                cn[0] = 0; cn[1] = cn[3]/3; cn[2] = cn[3]*2/3;
                return(0);              /* unhappy but non-fatal return value */
        }
        wlpt[1] = 588.f;                /* tuned for standard green channel */
        wlpt[2] = 480.f;
        if (cn[3] == 3) {               /* nothing to tune? */
                cn[0] = 0; cn[1] = 1; cn[2] = 2;
        } else {                        /* else find nearest color indices */
                double  curwl[3];
                memset(curwl, 0, sizeof(curwl));
                for (i = cn[3]; i--; ) {
                        const float     cwl = (i+.5f)/cn[3]*(wlpt[3]-wlpt[0]) + wlpt[0];
                        for (j = 3; j--; )
                                if (fabs(cwl - PKWL[j]) < fabs(curwl[j] - PKWL[j])) {
                                        curwl[j] = cwl;
                                        cn[j] = i;
                                }
                }
        }
        return(1);                      /* happy return value */
}


void
setscolor(                      /* assign spectral color from RGB */
        SCOLOR scol,
        double r,
        double g,
        double b
)
{
        const double    step = (WLPART[3] - WLPART[0])/(double)NCSAMP;
        double          cwl = WLPART[0] + .5*step;
        int             i;

        for (i = 0; i < NCSAMP; i++) {
                if (cwl >= WLPART[1])
                        scol[i] = r;
                else if (cwl >= WLPART[2])
                        scol[i] = g;
                else
                        scol[i] = b;
                cwl += step;
        }
}


void
scolor2color(                   /* assign RGB color from spectrum */
        COLOR col,
        SCOLOR scol,            /* uses average over bands */
        int ncs,
        float wlpt[4]
)
{
        const double    step = (wlpt[3] - wlpt[0])/(double)ncs;
        double          cwl = wlpt[0] + .5*step;
        int             i, j=0, n=0;

        setcolor(col, 0, 0, 0);
        for (i = 0; i < ncs; i++) {
                if (cwl < wlpt[j+1]) {
                        if (n > 1) col[j] /= (COLORV)n;
                        j++;
                        n = 0;
                }
                col[j] += scol[i];
                n++;
                cwl += step;
        }
        if (n > 1) col[j] /= (COLORV)n;
}


void
scolor2colr(                    /* assign RGBE from spectral color */
        COLR clr,
        SCOLOR scol,            /* uses average over bands */
        int ncs,
        float wlpt[4]
)
{
        COLOR   col;

        scolor2color(col, scol, ncs, wlpt);
        setcolr(clr, col[RED], col[GRN], col[BLU]);
}


void
scolor2scolr(                   /* float spectrum to common exponent */
        SCOLR sclr,
        SCOLOR scol,
        int ncs
)
{
        int     i = ncs;
        COLORV  p = scol[--i];

        while (i)
                if (scol[--i] > p)
                        p = scol[i];
        if (p <= 1e-32) {
                memset(sclr, 0, ncs+1);
                return;
        }
        p = frexp(p, &i) * 256.0 / p;
        sclr[ncs] = i + COLXS;
        for (i = ncs; i--; )
                sclr[i] = (scol[i] > 0) * (int)(scol[i]*p);
}


void
scolr2scolor(                   /* common exponent to float spectrum */
        SCOLOR scol,
        SCOLR sclr,
        int ncs
)
{
        double  f;
        int     i;

        if (sclr[ncs] == 0) {
                memset(scol, 0, sizeof(COLORV)*ncs);
                return;
        }
        f = ldexp(1.0, (int)sclr[ncs]-(COLXS+8));

        for (i = ncs; i--; )
                scol[i] = (sclr[i] + 0.5)*f;
}


double
scolor_mean(                    /* compute average for spectral color */
        SCOLOR  scol
)
{
        int     i = NCSAMP;
        double  sum = 0;

        while (i--)
                sum += scol[i];

        return sum/(double)NCSAMP;
}


double
sintens(                        /* find maximum value from spectrum */
        SCOLOR  scol
)
{
        int     i = NCSAMP;
        COLORV  peak = scol[--i];

        while (i)
                if (scol[--i] > peak)
                        peak = scol[i];

        return peak;
}


void
convertscolor(                  /* spectrum conversion, zero-fill ends */
        SCOLOR dst,             /* destination spectrum */
        int dnc,                /* destination # of spectral samples/intervals */
        double dwl0,            /* starting destination wavelength (longer) */
        double dwl1,            /* ending destination wavelength (shorter) */
        const COLORV src[],     /* source spectrum array */
        int snc,
        double swl0,            /* long/short wavelengths may be reversed */
        double swl1
)
{
        const int       sdir = 1 - 2*(swl0 < swl1);
        const double    sstp = (swl1 - swl0)/(double)snc;
        const double    dstp = (dwl1 - dwl0)/(double)dnc;
        const double    rdstp = 1./dstp;
        int             si, ssi, di;
        double          wl;

        if ((dnc < 3) | (dwl0 <= dwl1) | (dst == src))
                return;         /* invalid destination */

        if (dnc == snc && (dwl0-swl0)*(dwl0-swl0) + (dwl1-swl1)*(dwl1-swl1) <= .5) {
                memcpy(dst, src, sizeof(COLORV)*dnc);
                return;         /* same spectral sampling */
        }
        memset(dst, 0, sizeof(COLORV)*dnc);
                                /* set starting positions */
        if ((sdir>0 ? swl0 : swl1) <= dwl0) {
                if (sdir > 0) {
                        wl = swl0;
                        ssi = 0;
                } else {
                        wl = swl1;
                        ssi = snc-1;
                }
                si = 0;
                di = (wl - dwl0)*rdstp;
        } else {
                wl = dwl0;
                si = (wl - swl0)/sstp;
                ssi = sdir > 0 ? si : snc-1 - si;
                di = 0;
        }
        swl0 += (sdir < 0)*sstp;
                                /* step through intervals */
        while ((si < snc) & (di < dnc)) {
                double  intvl;
                if (swl0 + (ssi+sdir)*sstp < dwl0 + (di+1)*dstp) {
                        intvl = dwl0 + (di+1)*dstp - wl;
                        dst[di++] += src[ssi]*intvl*rdstp;
                } else {
                        intvl = swl0 + (ssi+sdir)*sstp - wl;
                        dst[di] += src[ssi]*intvl*rdstp;
                        ssi += sdir;
                        si++;
                }
                wl += intvl;
        }
}


void *
tempbuffer(                     /* get a temporary buffer */
        size_t  len
)
{
        static void     *tempbuf = NULL;
        static size_t   tempbuflen = 0;

        if (!len) {             /* call to free */
                if (tempbuflen) {
                        free(tempbuf);
                        tempbuf = NULL;
                        tempbuflen = 0;
                }
                return(NULL);
        }
        if (len <= tempbuflen)  /* big enough already? */
                return(tempbuf);
                                /* else free & reallocate */
        if (tempbuflen)
                free(tempbuf);
        tempbuf = malloc(len);
        tempbuflen = len*(tempbuf != NULL);
        return(tempbuf);
}


int
fwritecolrs(                    /* write out a colr scanline */
        COLR  *scanline,
        int  len,
        FILE  *fp
)
{
        int  i, j, beg, cnt = 1;
        int  c2;
        
        if ((len < MINELEN) | (len > MAXELEN))  /* OOBs, write out flat */
                return(fwrite((char *)scanline,sizeof(COLR),len,fp) - len);
                                        /* put magic header */
        putc(2, fp);
        putc(2, fp);
        putc(len>>8, fp);
        putc(len&0xff, fp);
                                        /* put components seperately */
        for (i = 0; i < 4; i++) {
            for (j = 0; j < len; j += cnt) {    /* find next run */
                for (beg = j; beg < len; beg += cnt) {
                    for (cnt = 1; (cnt < 127) & (beg+cnt < len) &&
                            scanline[beg+cnt][i] == scanline[beg][i]; cnt++)
                        ;
                    if (cnt >= MINRUN)
                        break;                  /* long enough */
                }
                if ((beg-j > 1) & (beg-j < MINRUN)) {
                    c2 = j+1;
                    while (scanline[c2++][i] == scanline[j][i])
                        if (c2 == beg) {        /* short run */
                            putc(128+beg-j, fp);
                            putc(scanline[j][i], fp);
                            j = beg;
                            break;
                        }
                }
                while (j < beg) {               /* write out non-run */
                    if ((c2 = beg-j) > 128) c2 = 128;
                    putc(c2, fp);
                    while (c2--)
                        putc(scanline[j++][i], fp);
                }
                if (cnt >= MINRUN) {            /* write out run */
                    putc(128+cnt, fp);
                    putc(scanline[beg][i], fp);
                } else
                    cnt = 0;
            }
        }
        return(ferror(fp) ? -1 : 0);
}

/*
 * An old-format scanline is either a stream of valid RGBE or XYZE real
 * pixels or at least one real pixel followed by some number of
 * invalid real pixels of the form (1,1,1,n), where n is a count.
 * These can themselves be repeated to create a multibyte repeat
 * count, with the least significant byte first (little-endian order.)
 * Repeat counts are limited by the size of an int; if a repetition
 * leads to an overrun, the rest of the the repetition will be
 * silently ignored.
 */
static int
oldreadcolrs(                   /* read in an old-style colr scanline */
        COLR  *scanline,
        int  len,
        FILE  *fp
)
{
        int  rshift = 0;
        int  i;
        
        while (len > 0) {
                scanline[0][RED] = getc(fp);
                scanline[0][GRN] = getc(fp);
                scanline[0][BLU] = getc(fp);
                scanline[0][EXP] = i = getc(fp);
                if (i == EOF)
                        return(-1);
                if (scanline[0][GRN] == 1 &&
                                (scanline[0][RED] == 1) &
                                (scanline[0][BLU] == 1)) {
                        i = scanline[0][EXP] << rshift;
                        while (i--) {
                                copycolr(scanline[0], scanline[-1]);
                                if (--len <= 0)
                                        return(0);
                                scanline++;
                        }
                        rshift += 8;
                } else {
                        scanline++;
                        len--;
                        rshift = 0;
                }
        }
        return(0);
}

/* 
 * There are two scanline formats: old and new.  The old format
 * compresses runs of RGBE or XYZE four-byte real pixels; the new
 * format breaks the pixels into R, G, B, and E lines (or XYZE lines)
 * which are individually run-length encoded.
 *
 * An old-format scanline always begins with a valid real pixel; at
 * least one of the RGB (or XYZ) values will have its high-order bit
 * set.  A new-format scanline begins with four bytes which are not a
 * valid real pixel: (2, 2, lenhigh, lenlow) where lenhigh is always
 * less than 128 and hence never has a high-order bit set.
 *
 * A new-format scanline is broken into its RGBE or XYZE components.
 * Each is output and run-length encoded separately so that a scanline
 * is broken into four records.  In turn, each record is organized
 * into chunks of up to 128 characters, which begin with a count byte.
 * If the count byte is greater than 128, the following data byte is
 * repeated (count-128) times.  If not, the count byte is followed by
 * that many data bytes.
 */
int
freadcolrs(                     /* read in an encoded colr scanline */
        COLR  *scanline,
        int  len,
        FILE  *fp
)
{
        int  i, j;
        int  code, val;
                                        /* determine scanline type */
        if (len <= 0)
                return(0);
        if ((i = getc(fp)) == EOF)
                return(-1);
        scanline[0][RED] = i;
        scanline[0][GRN] = getc(fp);
        scanline[0][BLU] = getc(fp);
        if ((i = getc(fp)) == EOF)
                return(-1);
        if ((scanline[0][RED] != 2) | (scanline[0][GRN] != 2) |
                        (scanline[0][BLU] & 0x80)) {
                scanline[0][EXP] = i;
                return(oldreadcolrs(scanline+1, len-1, fp));
        }
        if ((scanline[0][BLU]<<8 | i) != len)
                return(-1);             /* length mismatch! */
                                        /* read each component */
        for (i = 0; i < 4; i++)
            for (j = 0; j < len; ) {
                if ((code = getc(fp)) == EOF)
                    return(-1);
                if (code > 128) {       /* run */
                    code &= 127;
                    if ((val = getc(fp)) == EOF)
                        return -1;
                    if (j + code > len)
                        return -1;      /* overrun */
                    while (code--)
                        scanline[j++][i] = val;
                } else {                /* non-run */
                    if (j + code > len)
                        return -1;      /* overrun */
                    while (code--) {
                        if ((val = getc(fp)) == EOF)
                            return -1;
                        scanline[j++][i] = val;
                    }
                }
            }
        return(0);
}


int
fwritescan(                     /* write out a scanline */
        COLOR  *scanline,
        int  len,
        FILE  *fp
)
{
        COLR  *clrscan;
        int  n;
        COLR  *sp;
                                        /* get scanline buffer */
        if ((sp = (COLR *)tempbuffer(len*sizeof(COLR))) == NULL)
                return(-1);
        clrscan = sp;
                                        /* convert scanline */
        n = len;
        while (n-- > 0) {
                setcolr(sp[0], scanline[0][RED],
                                  scanline[0][GRN],
                                  scanline[0][BLU]);
                scanline++;
                sp++;
        }
        return(fwritecolrs(clrscan, len, fp));
}


int
freadscan(                      /* read in a scanline */
        COLOR  *scanline,
        int  len,
        FILE  *fp
)
{
        COLR  *clrscan;

        if ((clrscan = (COLR *)tempbuffer(len*sizeof(COLR))) == NULL)
                return(-1);
        if (freadcolrs(clrscan, len, fp) < 0)
                return(-1);
                                        /* convert scanline */
        colr_color(scanline[0], clrscan[0]);
        while (--len > 0) {
                scanline++; clrscan++;
                if (clrscan[0][GRN] == clrscan[-1][GRN] &&
                            (clrscan[0][RED] == clrscan[-1][RED]) &
                            (clrscan[0][BLU] == clrscan[-1][BLU]) &
                            (clrscan[0][EXP] == clrscan[-1][EXP]))
                        copycolor(scanline[0], scanline[-1]);
                else
                        colr_color(scanline[0], clrscan[0]);
        }
        return(0);
}


void
setcolr(                        /* assign a short color value */
        COLR  clr,
        double  r,
        double  g,
        double  b
)
{
        double  d;
        int  e;
        
        d = r > g ? r : g;
        if (b > d) d = b;

        if (d <= 1e-32) {
                clr[RED] = clr[GRN] = clr[BLU] = 0;
                clr[EXP] = 0;
                return;
        }

        d = frexp(d, &e) * 256.0 / d;

        clr[RED] = (r > 0) * (int)(r*d);
        clr[GRN] = (g > 0) * (int)(g*d);
        clr[BLU] = (b > 0) * (int)(b*d);
        clr[EXP] = e + COLXS;
}


void
colr_color(                     /* convert short to float color */
        COLOR  col,
        COLR  clr
)
{
        double  f;
        
        if (clr[EXP] == 0) {
                col[RED] = col[GRN] = col[BLU] = 0.0;
                return;
        }
        f = ldexp(1.0, (int)clr[EXP]-(COLXS+8));
        col[RED] = (clr[RED] + 0.5)*f;
        col[GRN] = (clr[GRN] + 0.5)*f;
        col[BLU] = (clr[BLU] + 0.5)*f;
}


int
bigdiff(                                /* c1 delta c2 > md? */
        COLOR  c1,
        COLOR  c2,
        double  md
)
{
        int  i;

        for (i = 0; i < 3; i++)
                if ((colval(c1,i)-colval(c2,i) > md*colval(c2,i)) |
                                (colval(c2,i)-colval(c1,i) > md*colval(c1,i)))
                        return(1);
        return(0);
}


int
sbigsdiff(                              /* sc1 delta sc2 > md? */
        SCOLOR  c1,
        SCOLOR  c2,
        double  md
)
{
        int  i = NCSAMP;

        while (i--)
                if ((c1[i]-c2[i] > md*c2[i]) | (c2[i]-c1[i] > md*c1[i]))
                        return(1);
        return(0);
}
Revision:	2.27
Committed:	Wed Nov 15 18:02:52 2023 UTC (5 months, 4 weeks ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.26:	+287 -25 lines
Log Message:	feat(rpict,rtrace,rcontrib,rtpict): Hyperspectral rendering (except photon map)
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.27	static const char RCSid[] = "$Id: color.c,v 2.X in progress $";
3	greg	1.1	#endif
4			/*
5			* color.c - routines for color calculations.
6			*
7	greg	2.9	* Externals declared in color.h
8			*/
9
10	greg	2.10	#include "copyright.h"
11	greg	1.1
12			#include <stdio.h>
13	greg	2.9	#include <stdlib.h>
14	greg	2.7	#include <math.h>
15	greg	1.1	#include "color.h"
16	greg	2.14
17			#ifdef getc_unlocked /* avoid horrendous overhead of flockfile */
18	greg	2.15	#undef getc
19			#undef putc
20	greg	2.19	#undef ferror
21	greg	2.14	#define getc getc_unlocked
22			#define putc putc_unlocked
23	greg	2.18	#define ferror ferror_unlocked
24	greg	2.14	#endif
25	greg	1.1
26	greg	1.14	#define MINELEN 8 /* minimum scanline length for encoding */
27	greg	2.6	#define MAXELEN 0x7fff /* maximum scanline length for encoding */
28	greg	1.14	#define MINRUN 4 /* minimum run length */
29
30	greg	2.4
31	greg	2.27	int CNDX[4] = {0,1,2,3}; /* RGBE indices for SCOLOR, SCOLR */
32			float WLPART[4] = {780,588,480,380}; /* RGB wavelength limits+partitions (nm) */
33
34
35			int
36			setspectrsamp( /* assign spectral sampling, 1 if good, -1 if bad */
37			int cn[4], /* input cn[3]=nsamps */
38			float wlpt[4] /* input wlpt[0],wlpt[3]=extrema */
39			)
40			{
41			static const float PKWL[3] = {607, 553, 469};
42			int i, j;
43
44			if (cn[3] < 3)
45			return(-1); /* reject this */
46
47			if (wlpt[0] < wlpt[3]) {
48			float tf = wlpt[0];
49			wlpt[0] = wlpt[3]; wlpt[3] = tf;
50			}
51			if (wlpt[0] - wlpt[3] < 50.f)
52			return(-1); /* also reject */
53
54			if (cn[3] > MAXCSAMP)
55			cn[3] = MAXCSAMP;
56
57			if ((wlpt[3] >= PKWL[2]) \| (wlpt[0] <= PKWL[0])) {
58			wlpt[1] = wlpt[0] + 0.333333f*(wlpt[3]-wlpt[0]);
59			wlpt[2] = wlpt[0] + 0.666667f*(wlpt[3]-wlpt[0]);
60			cn[0] = 0; cn[1] = cn[3]/3; cn[2] = cn[3]*2/3;
61			return(0); /* unhappy but non-fatal return value */
62			}
63			wlpt[1] = 588.f; /* tuned for standard green channel */
64			wlpt[2] = 480.f;
65			if (cn[3] == 3) { /* nothing to tune? */
66			cn[0] = 0; cn[1] = 1; cn[2] = 2;
67			} else { /* else find nearest color indices */
68			double curwl[3];
69			memset(curwl, 0, sizeof(curwl));
70			for (i = cn[3]; i--; ) {
71			const float cwl = (i+.5f)/cn[3]*(wlpt[3]-wlpt[0]) + wlpt[0];
72			for (j = 3; j--; )
73			if (fabs(cwl - PKWL[j]) < fabs(curwl[j] - PKWL[j])) {
74			curwl[j] = cwl;
75			cn[j] = i;
76			}
77			}
78			}
79			return(1); /* happy return value */
80			}
81
82
83			void
84			setscolor( /* assign spectral color from RGB */
85			SCOLOR scol,
86			double r,
87			double g,
88			double b
89			)
90			{
91			const double step = (WLPART[3] - WLPART[0])/(double)NCSAMP;
92			double cwl = WLPART[0] + .5*step;
93			int i;
94
95			for (i = 0; i < NCSAMP; i++) {
96			if (cwl >= WLPART[1])
97			scol[i] = r;
98			else if (cwl >= WLPART[2])
99			scol[i] = g;
100			else
101			scol[i] = b;
102			cwl += step;
103			}
104			}
105
106
107			void
108			scolor2color( /* assign RGB color from spectrum */
109			COLOR col,
110			SCOLOR scol, /* uses average over bands */
111			int ncs,
112			float wlpt[4]
113			)
114			{
115			const double step = (wlpt[3] - wlpt[0])/(double)ncs;
116			double cwl = wlpt[0] + .5*step;
117			int i, j=0, n=0;
118
119			setcolor(col, 0, 0, 0);
120			for (i = 0; i < ncs; i++) {
121			if (cwl < wlpt[j+1]) {
122			if (n > 1) col[j] /= (COLORV)n;
123			j++;
124			n = 0;
125			}
126			col[j] += scol[i];
127			n++;
128			cwl += step;
129			}
130			if (n > 1) col[j] /= (COLORV)n;
131			}
132
133
134			void
135			scolor2colr( /* assign RGBE from spectral color */
136			COLR clr,
137			SCOLOR scol, /* uses average over bands */
138			int ncs,
139			float wlpt[4]
140			)
141			{
142			COLOR col;
143
144			scolor2color(col, scol, ncs, wlpt);
145			setcolr(clr, col[RED], col[GRN], col[BLU]);
146			}
147
148
149			void
150			scolor2scolr( /* float spectrum to common exponent */
151			SCOLR sclr,
152			SCOLOR scol,
153			int ncs
154			)
155			{
156			int i = ncs;
157			COLORV p = scol[--i];
158
159			while (i)
160			if (scol[--i] > p)
161			p = scol[i];
162			if (p <= 1e-32) {
163			memset(sclr, 0, ncs+1);
164			return;
165			}
166			p = frexp(p, &i) * 256.0 / p;
167			sclr[ncs] = i + COLXS;
168			for (i = ncs; i--; )
169			sclr[i] = (scol[i] > 0) * (int)(scol[i]*p);
170			}
171
172
173			void
174			scolr2scolor( /* common exponent to float spectrum */
175			SCOLOR scol,
176			SCOLR sclr,
177			int ncs
178			)
179			{
180			double f;
181			int i;
182
183			if (sclr[ncs] == 0) {
184			memset(scol, 0, sizeof(COLORV)*ncs);
185			return;
186			}
187			f = ldexp(1.0, (int)sclr[ncs]-(COLXS+8));
188
189			for (i = ncs; i--; )
190			scol[i] = (sclr[i] + 0.5)*f;
191			}
192
193
194			double
195			scolor_mean( /* compute average for spectral color */
196			SCOLOR scol
197			)
198			{
199			int i = NCSAMP;
200			double sum = 0;
201
202			while (i--)
203			sum += scol[i];
204
205			return sum/(double)NCSAMP;
206			}
207
208
209			double
210			sintens( /* find maximum value from spectrum */
211			SCOLOR scol
212			)
213			{
214			int i = NCSAMP;
215			COLORV peak = scol[--i];
216
217			while (i)
218			if (scol[--i] > peak)
219			peak = scol[i];
220
221			return peak;
222			}
223
224
225			void
226			convertscolor( /* spectrum conversion, zero-fill ends */
227			SCOLOR dst, /* destination spectrum */
228			int dnc, /* destination # of spectral samples/intervals */
229			double dwl0, /* starting destination wavelength (longer) */
230			double dwl1, /* ending destination wavelength (shorter) */
231			const COLORV src[], /* source spectrum array */
232			int snc,
233			double swl0, /* long/short wavelengths may be reversed */
234			double swl1
235			)
236			{
237			const int sdir = 1 - 2*(swl0 < swl1);
238			const double sstp = (swl1 - swl0)/(double)snc;
239			const double dstp = (dwl1 - dwl0)/(double)dnc;
240			const double rdstp = 1./dstp;
241			int si, ssi, di;
242			double wl;
243
244			if ((dnc < 3) \| (dwl0 <= dwl1) \| (dst == src))
245			return; /* invalid destination */
246
247			if (dnc == snc && (dwl0-swl0)(dwl0-swl0) + (dwl1-swl1)(dwl1-swl1) <= .5) {
248			memcpy(dst, src, sizeof(COLORV)*dnc);
249			return; /* same spectral sampling */
250			}
251			memset(dst, 0, sizeof(COLORV)*dnc);
252			/* set starting positions */
253			if ((sdir>0 ? swl0 : swl1) <= dwl0) {
254			if (sdir > 0) {
255			wl = swl0;
256			ssi = 0;
257			} else {
258			wl = swl1;
259			ssi = snc-1;
260			}
261			si = 0;
262			di = (wl - dwl0)*rdstp;
263			} else {
264			wl = dwl0;
265			si = (wl - swl0)/sstp;
266			ssi = sdir > 0 ? si : snc-1 - si;
267			di = 0;
268			}
269			swl0 += (sdir < 0)*sstp;
270			/* step through intervals */
271			while ((si < snc) & (di < dnc)) {
272			double intvl;
273			if (swl0 + (ssi+sdir)sstp < dwl0 + (di+1)dstp) {
274			intvl = dwl0 + (di+1)*dstp - wl;
275			dst[di++] += src[ssi]intvlrdstp;
276			} else {
277			intvl = swl0 + (ssi+sdir)*sstp - wl;
278			dst[di] += src[ssi]intvlrdstp;
279			ssi += sdir;
280			si++;
281			}
282			wl += intvl;
283			}
284			}
285
286
287	greg	2.22	void *
288	greg	2.17	tempbuffer( /* get a temporary buffer */
289	greg	2.27	size_t len
290	greg	2.17	)
291	greg	1.14	{
292	greg	2.27	static void *tempbuf = NULL;
293			static size_t tempbuflen = 0;
294	greg	1.14
295	greg	2.22	if (!len) { /* call to free */
296			if (tempbuflen) {
297	greg	2.20	free(tempbuf);
298	greg	2.22	tempbuf = NULL;
299			tempbuflen = 0;
300			}
301			return(NULL);
302	greg	1.14	}
303	greg	2.22	if (len <= tempbuflen) /* big enough already? */
304			return(tempbuf);
305			/* else free & reallocate */
306			if (tempbuflen)
307			free(tempbuf);
308			tempbuf = malloc(len);
309			tempbuflen = len*(tempbuf != NULL);
310	greg	1.14	return(tempbuf);
311			}
312
313
314	greg	2.9	int
315	greg	2.17	fwritecolrs( /* write out a colr scanline */
316			COLR *scanline,
317			int len,
318			FILE *fp
319			)
320	greg	1.1	{
321	greg	2.17	int i, j, beg, cnt = 1;
322	greg	1.14	int c2;
323	greg	1.1
324	schorsch	2.13	if ((len < MINELEN) \| (len > MAXELEN)) /* OOBs, write out flat */
325	greg	1.14	return(fwrite((char *)scanline,sizeof(COLR),len,fp) - len);
326	greg	2.2	/* put magic header */
327			putc(2, fp);
328	greg	1.14	putc(2, fp);
329			putc(len>>8, fp);
330	greg	2.21	putc(len&0xff, fp);
331	greg	1.14	/* put components seperately */
332			for (i = 0; i < 4; i++) {
333			for (j = 0; j < len; j += cnt) { /* find next run */
334			for (beg = j; beg < len; beg += cnt) {
335	greg	2.20	for (cnt = 1; (cnt < 127) & (beg+cnt < len) &&
336	greg	1.14	scanline[beg+cnt][i] == scanline[beg][i]; cnt++)
337			;
338			if (cnt >= MINRUN)
339			break; /* long enough */
340	greg	1.1	}
341	greg	2.20	if ((beg-j > 1) & (beg-j < MINRUN)) {
342	greg	1.15	c2 = j+1;
343			while (scanline[c2++][i] == scanline[j][i])
344			if (c2 == beg) { /* short run */
345			putc(128+beg-j, fp);
346			putc(scanline[j][i], fp);
347			j = beg;
348			break;
349			}
350			}
351			while (j < beg) { /* write out non-run */
352	greg	1.14	if ((c2 = beg-j) > 128) c2 = 128;
353			putc(c2, fp);
354			while (c2--)
355			putc(scanline[j++][i], fp);
356			}
357			if (cnt >= MINRUN) { /* write out run */
358			putc(128+cnt, fp);
359			putc(scanline[beg][i], fp);
360			} else
361			cnt = 0;
362			}
363	greg	1.1	}
364			return(ferror(fp) ? -1 : 0);
365			}
366
367	greg	2.23	/*
368			* An old-format scanline is either a stream of valid RGBE or XYZE real
369			* pixels or at least one real pixel followed by some number of
370			* invalid real pixels of the form (1,1,1,n), where n is a count.
371			* These can themselves be repeated to create a multibyte repeat
372			* count, with the least significant byte first (little-endian order.)
373			* Repeat counts are limited by the size of an int; if a repetition
374			* leads to an overrun, the rest of the the repetition will be
375			* silently ignored.
376			*/
377	greg	2.9	static int
378	greg	2.19	oldreadcolrs( /* read in an old-style colr scanline */
379	greg	2.17	COLR *scanline,
380			int len,
381			FILE *fp
382			)
383	greg	2.9	{
384	greg	2.25	int rshift = 0;
385	greg	2.17	int i;
386	greg	2.9
387			while (len > 0) {
388			scanline[0][RED] = getc(fp);
389			scanline[0][GRN] = getc(fp);
390			scanline[0][BLU] = getc(fp);
391	greg	2.18	scanline[0][EXP] = i = getc(fp);
392			if (i == EOF)
393	greg	2.9	return(-1);
394	greg	2.20	if (scanline[0][GRN] == 1 &&
395			(scanline[0][RED] == 1) &
396	greg	2.25	(scanline[0][BLU] == 1)) {
397	greg	2.20	i = scanline[0][EXP] << rshift;
398			while (i--) {
399	greg	2.9	copycolr(scanline[0], scanline[-1]);
400	greg	2.20	if (--len <= 0)
401			return(0);
402	greg	2.9	scanline++;
403			}
404			rshift += 8;
405			} else {
406			scanline++;
407			len--;
408			rshift = 0;
409			}
410			}
411			return(0);
412			}
413
414	greg	2.23	/*
415			* There are two scanline formats: old and new. The old format
416			* compresses runs of RGBE or XYZE four-byte real pixels; the new
417			* format breaks the pixels into R, G, B, and E lines (or XYZE lines)
418			* which are individually run-length encoded.
419			*
420			* An old-format scanline always begins with a valid real pixel; at
421			* least one of the RGB (or XYZ) values will have its high-order bit
422			* set. A new-format scanline begins with four bytes which are not a
423			* valid real pixel: (2, 2, lenhigh, lenlow) where lenhigh is always
424			* less than 128 and hence never has a high-order bit set.
425			*
426			* A new-format scanline is broken into its RGBE or XYZE components.
427			* Each is output and run-length encoded separately so that a scanline
428			* is broken into four records. In turn, each record is organized
429			* into chunks of up to 128 characters, which begin with a count byte.
430			* If the count byte is greater than 128, the following data byte is
431			* repeated (count-128) times. If not, the count byte is followed by
432			* that many data bytes.
433			*/
434	greg	2.9	int
435	greg	2.17	freadcolrs( /* read in an encoded colr scanline */
436			COLR *scanline,
437			int len,
438			FILE *fp
439			)
440	greg	1.1	{
441	greg	2.17	int i, j;
442	greg	2.6	int code, val;
443	greg	1.14	/* determine scanline type */
444	greg	2.26	if (len <= 0)
445			return(0);
446	greg	1.14	if ((i = getc(fp)) == EOF)
447			return(-1);
448	greg	2.26	scanline[0][RED] = i;
449	greg	1.14	scanline[0][GRN] = getc(fp);
450			scanline[0][BLU] = getc(fp);
451			if ((i = getc(fp)) == EOF)
452			return(-1);
453	greg	2.26	if ((scanline[0][RED] != 2) \| (scanline[0][GRN] != 2) \|
454			(scanline[0][BLU] & 0x80)) {
455	greg	1.14	scanline[0][EXP] = i;
456			return(oldreadcolrs(scanline+1, len-1, fp));
457			}
458			if ((scanline[0][BLU]<<8 \| i) != len)
459			return(-1); /* length mismatch! */
460			/* read each component */
461			for (i = 0; i < 4; i++)
462			for (j = 0; j < len; ) {
463			if ((code = getc(fp)) == EOF)
464			return(-1);
465			if (code > 128) { /* run */
466	greg	2.6	code &= 127;
467	greg	2.9	if ((val = getc(fp)) == EOF)
468			return -1;
469	greg	2.16	if (j + code > len)
470			return -1; /* overrun */
471	greg	2.6	while (code--)
472			scanline[j++][i] = val;
473	greg	2.16	} else { /* non-run */
474			if (j + code > len)
475			return -1; /* overrun */
476	greg	2.9	while (code--) {
477			if ((val = getc(fp)) == EOF)
478			return -1;
479			scanline[j++][i] = val;
480			}
481	greg	2.16	}
482	greg	1.14	}
483	greg	1.1	return(0);
484			}
485
486
487	greg	2.9	int
488	greg	2.17	fwritescan( /* write out a scanline */
489			COLOR *scanline,
490			int len,
491			FILE *fp
492			)
493	greg	1.1	{
494	greg	1.14	COLR *clrscan;
495			int n;
496	greg	2.17	COLR *sp;
497	greg	1.14	/* get scanline buffer */
498			if ((sp = (COLR )tempbuffer(lensizeof(COLR))) == NULL)
499			return(-1);
500			clrscan = sp;
501			/* convert scanline */
502			n = len;
503			while (n-- > 0) {
504			setcolr(sp[0], scanline[0][RED],
505	greg	1.1	scanline[0][GRN],
506			scanline[0][BLU]);
507			scanline++;
508	greg	1.14	sp++;
509	greg	1.1	}
510	greg	1.14	return(fwritecolrs(clrscan, len, fp));
511	greg	1.1	}
512
513
514	greg	2.9	int
515	greg	2.17	freadscan( /* read in a scanline */
516			COLOR *scanline,
517			int len,
518			FILE *fp
519			)
520	greg	1.1	{
521	greg	2.17	COLR *clrscan;
522	greg	1.14
523			if ((clrscan = (COLR )tempbuffer(lensizeof(COLR))) == NULL)
524			return(-1);
525			if (freadcolrs(clrscan, len, fp) < 0)
526			return(-1);
527			/* convert scanline */
528			colr_color(scanline[0], clrscan[0]);
529			while (--len > 0) {
530			scanline++; clrscan++;
531	greg	2.20	if (clrscan[0][GRN] == clrscan[-1][GRN] &&
532			(clrscan[0][RED] == clrscan[-1][RED]) &
533			(clrscan[0][BLU] == clrscan[-1][BLU]) &
534			(clrscan[0][EXP] == clrscan[-1][EXP]))
535	greg	1.14	copycolor(scanline[0], scanline[-1]);
536			else
537			colr_color(scanline[0], clrscan[0]);
538	greg	1.1	}
539			return(0);
540			}
541
542
543	greg	2.9	void
544	greg	2.17	setcolr( /* assign a short color value */
545			COLR clr,
546			double r,
547			double g,
548			double b
549			)
550	greg	1.1	{
551			double d;
552			int e;
553
554			d = r > g ? r : g;
555			if (b > d) d = b;
556
557	greg	1.4	if (d <= 1e-32) {
558	greg	1.1	clr[RED] = clr[GRN] = clr[BLU] = 0;
559			clr[EXP] = 0;
560			return;
561			}
562
563	greg	2.21	d = frexp(d, &e) * 256.0 / d;
564	greg	1.1
565	greg	2.27	clr[RED] = (r > 0) * (int)(r*d);
566			clr[GRN] = (g > 0) * (int)(g*d);
567			clr[BLU] = (b > 0) * (int)(b*d);
568	greg	1.1	clr[EXP] = e + COLXS;
569			}
570
571
572	greg	2.9	void
573	greg	2.17	colr_color( /* convert short to float color */
574			COLOR col,
575			COLR clr
576			)
577	greg	1.1	{
578	greg	1.6	double f;
579	greg	1.1
580	greg	2.27	if (clr[EXP] == 0) {
581	greg	1.1	col[RED] = col[GRN] = col[BLU] = 0.0;
582	greg	2.27	return;
583	greg	1.1	}
584	greg	2.27	f = ldexp(1.0, (int)clr[EXP]-(COLXS+8));
585			col[RED] = (clr[RED] + 0.5)*f;
586			col[GRN] = (clr[GRN] + 0.5)*f;
587			col[BLU] = (clr[BLU] + 0.5)*f;
588	greg	1.6	}
589
590
591	greg	2.9	int
592	greg	2.17	bigdiff( /* c1 delta c2 > md? */
593			COLOR c1,
594			COLOR c2,
595			double md
596			)
597	greg	1.7	{
598	greg	2.17	int i;
599	greg	1.7
600			for (i = 0; i < 3; i++)
601	greg	2.27	if ((colval(c1,i)-colval(c2,i) > md*colval(c2,i)) \|
602			(colval(c2,i)-colval(c1,i) > md*colval(c1,i)))
603			return(1);
604			return(0);
605			}
606
607
608			int
609			sbigsdiff( /* sc1 delta sc2 > md? */
610			SCOLOR c1,
611			SCOLOR c2,
612			double md
613			)
614			{
615			int i = NCSAMP;
616
617			while (i--)
618			if ((c1[i]-c2[i] > mdc2[i]) \| (c2[i]-c1[i] > mdc1[i]))
619	greg	1.7	return(1);
620			return(0);
621			}