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#ifndef lint |
2 |
static const char RCSid[] = "$Id: color.c,v 2.30 2023/11/21 01:30:20 greg Exp $"; |
3 |
#endif |
4 |
/* |
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* color.c - routines for color calculations. |
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* |
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* Externals declared in color.h |
8 |
*/ |
9 |
|
10 |
#include "copyright.h" |
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|
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <math.h> |
15 |
#include "color.h" |
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|
17 |
#ifdef getc_unlocked /* avoid horrendous overhead of flockfile */ |
18 |
#undef getc |
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#undef putc |
20 |
#undef ferror |
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#define getc getc_unlocked |
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#define putc putc_unlocked |
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#define ferror ferror_unlocked |
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#endif |
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|
26 |
#define MINELEN 8 /* minimum scanline length for encoding */ |
27 |
#define MAXELEN 0x7fff /* maximum scanline length for encoding */ |
28 |
#define MINRUN 4 /* minimum run length */ |
29 |
|
30 |
|
31 |
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) */ |
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|
34 |
|
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int |
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setspectrsamp( /* assign spectral sampling, 1 if good, -1 if bad */ |
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int cn[4], /* input cn[3]=nsamps */ |
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float wlpt[4] /* input wlpt[0],wlpt[3]=extrema */ |
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) |
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{ |
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static const float PKWL[3] = {607, 553, 469}; |
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int i, j; |
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|
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if (cn[3] < 3) |
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return(-1); /* reject this */ |
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|
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if (wlpt[0] < wlpt[3]) { |
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float tf = wlpt[0]; |
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wlpt[0] = wlpt[3]; wlpt[3] = tf; |
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} |
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if (wlpt[0] - wlpt[3] < 50.f) |
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return(-1); /* also reject */ |
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|
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if (cn[3] > MAXCSAMP) |
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cn[3] = MAXCSAMP; |
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|
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if ((wlpt[3] >= PKWL[2]) | (wlpt[0] <= PKWL[0])) { |
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wlpt[1] = wlpt[0] + 0.333333f*(wlpt[3]-wlpt[0]); |
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wlpt[2] = wlpt[0] + 0.666667f*(wlpt[3]-wlpt[0]); |
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cn[0] = 0; cn[1] = cn[3]/3; cn[2] = cn[3]*2/3; |
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return(0); /* unhappy but non-fatal return value */ |
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} |
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wlpt[1] = 588.f; /* tuned for standard green channel */ |
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wlpt[2] = 480.f; |
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if (cn[3] == 3) { /* nothing to tune? */ |
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cn[0] = 0; cn[1] = 1; cn[2] = 2; |
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} else { /* else find nearest color indices */ |
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double curwl[3]; |
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memset(curwl, 0, sizeof(curwl)); |
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for (i = cn[3]; i--; ) { |
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const float cwl = (i+.5f)/cn[3]*(wlpt[3]-wlpt[0]) + wlpt[0]; |
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for (j = 3; j--; ) |
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if (fabs(cwl - PKWL[j]) < fabs(curwl[j] - PKWL[j])) { |
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curwl[j] = cwl; |
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cn[j] = i; |
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} |
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} |
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} |
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return(1); /* happy return value */ |
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} |
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|
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|
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void |
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setscolor( /* assign spectral color from RGB */ |
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SCOLOR scol, |
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double r, |
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double g, |
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double b |
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) |
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{ |
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const double step = (WLPART[3] - WLPART[0])/(double)NCSAMP; |
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double cwl = WLPART[0] + .5*step; |
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int i; |
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|
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for (i = 0; i < NCSAMP; i++) { |
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if (cwl >= WLPART[1]) |
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scol[i] = r; |
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else if (cwl >= WLPART[2]) |
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scol[i] = g; |
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else |
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scol[i] = b; |
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cwl += step; |
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} |
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} |
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|
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|
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void |
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scolor2color( /* assign RGB color from spectrum */ |
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COLOR col, |
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SCOLOR scol, /* uses average over bands */ |
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int ncs, |
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const float wlpt[4] |
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) |
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{ |
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const double step = (wlpt[3] - wlpt[0])/(double)ncs; |
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double cwl = wlpt[0] + .5*step; |
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int i, j=0, n=0; |
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|
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setcolor(col, 0, 0, 0); |
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for (i = 0; i < ncs; i++) { |
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if (cwl < wlpt[j+1]) { |
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if (n > 1) col[j] /= (COLORV)n; |
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j++; |
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n = 0; |
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} |
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col[j] += scol[i]; |
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n++; |
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cwl += step; |
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} |
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if (n > 1) col[j] /= (COLORV)n; |
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} |
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|
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|
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void |
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scolor2colr( /* assign RGBE from spectral color */ |
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COLR clr, |
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SCOLOR scol, /* uses average over bands */ |
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int ncs, |
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const float wlpt[4] |
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) |
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{ |
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COLOR col; |
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|
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scolor2color(col, scol, ncs, wlpt); |
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setcolr(clr, col[RED], col[GRN], col[BLU]); |
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} |
147 |
|
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|
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void |
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scolor2scolr( /* float spectrum to common exponent */ |
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SCOLR sclr, |
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SCOLOR scol, |
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int ncs |
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) |
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{ |
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int i = ncs; |
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COLORV p = scol[--i]; |
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|
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while (i) |
160 |
if (scol[--i] > p) |
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p = scol[i]; |
162 |
if (p <= 1e-32) { |
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memset(sclr, 0, ncs+1); |
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return; |
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} |
166 |
p = frexp(p, &i) * 256.0 / p; |
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sclr[ncs] = i + COLXS; |
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for (i = ncs; i--; ) |
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sclr[i] = (scol[i] > 0) * (int)(scol[i]*p); |
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} |
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|
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|
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void |
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scolr2scolor( /* common exponent to float spectrum */ |
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SCOLOR scol, |
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SCOLR sclr, |
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int ncs |
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) |
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{ |
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double f; |
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int i; |
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|
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if (sclr[ncs] == 0) { |
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memset(scol, 0, sizeof(COLORV)*ncs); |
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return; |
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} |
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f = ldexp(1.0, (int)sclr[ncs]-(COLXS+8)); |
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|
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for (i = ncs; i--; ) |
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scol[i] = (sclr[i] + 0.5)*f; |
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} |
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|
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|
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double |
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scolor_mean( /* compute average for spectral color */ |
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SCOLOR scol |
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) |
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{ |
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int i = NCSAMP; |
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double sum = 0; |
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|
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while (i--) |
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sum += scol[i]; |
204 |
|
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return sum/(double)NCSAMP; |
206 |
} |
207 |
|
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|
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double |
210 |
sintens( /* find maximum value from spectrum */ |
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SCOLOR scol |
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) |
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{ |
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int i = NCSAMP; |
215 |
COLORV peak = scol[--i]; |
216 |
|
217 |
while (i) |
218 |
if (scol[--i] > peak) |
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peak = scol[i]; |
220 |
|
221 |
return peak; |
222 |
} |
223 |
|
224 |
|
225 |
void |
226 |
convertscolor( /* spectrum conversion, zero-fill ends */ |
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SCOLOR dst, /* destination spectrum */ |
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int dnc, /* destination # of spectral samples/intervals */ |
229 |
double dwl0, /* starting destination wavelength (longer) */ |
230 |
double dwl1, /* ending destination wavelength (shorter) */ |
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const COLORV src[], /* source spectrum array */ |
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int snc, |
233 |
double swl0, /* long/short wavelengths may be reversed */ |
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double swl1 |
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) |
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{ |
237 |
const int sdir = 1 - 2*(swl0 < swl1); |
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const double sstp = (swl1 - swl0)/(double)snc; |
239 |
const double dstp = (dwl1 - dwl0)/(double)dnc; |
240 |
const double rdstp = 1./dstp; |
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int si, ssi, di; |
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double wl; |
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|
244 |
if ((dnc < 3) | (dwl0 <= dwl1) | (dst == src)) |
245 |
return; /* invalid destination */ |
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|
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if (dnc == snc && (dwl0-swl0)*(dwl0-swl0) + (dwl1-swl1)*(dwl1-swl1) <= .5) { |
248 |
memcpy(dst, src, sizeof(COLORV)*dnc); |
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return; /* same spectral sampling */ |
250 |
} |
251 |
memset(dst, 0, sizeof(COLORV)*dnc); |
252 |
/* set starting positions */ |
253 |
if ((sdir>0 ? swl0 : swl1) <= dwl0) { |
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if (sdir > 0) { |
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wl = swl0; |
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ssi = 0; |
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} else { |
258 |
wl = swl1; |
259 |
ssi = snc-1; |
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} |
261 |
si = 0; |
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di = (wl - dwl0)*rdstp; |
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} else { |
264 |
wl = dwl0; |
265 |
if (sdir > 0) { |
266 |
ssi = si = (wl - swl0)/sstp; |
267 |
} else { |
268 |
si = (wl - swl1)/sstp; |
269 |
ssi = snc-1 - si; |
270 |
} |
271 |
di = 0; |
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} |
273 |
swl0 += (sdir < 0)*sstp; |
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/* step through intervals */ |
275 |
while ((si < snc) & (di < dnc)) { |
276 |
double intvl; |
277 |
if (swl0 + (ssi+sdir)*sstp < dwl0 + (di+1)*dstp) { |
278 |
intvl = dwl0 + (di+1)*dstp - wl; |
279 |
dst[di++] += src[ssi]*intvl*rdstp; |
280 |
} else { |
281 |
intvl = swl0 + (ssi+sdir)*sstp - wl; |
282 |
dst[di] += src[ssi]*intvl*rdstp; |
283 |
ssi += sdir; |
284 |
si++; |
285 |
} |
286 |
wl += intvl; |
287 |
} |
288 |
} |
289 |
|
290 |
|
291 |
void * |
292 |
tempbuffer( /* get a temporary buffer */ |
293 |
size_t len |
294 |
) |
295 |
{ |
296 |
static void *tempbuf = NULL; |
297 |
static size_t tempbuflen = 0; |
298 |
|
299 |
if (!len) { /* call to free */ |
300 |
if (tempbuflen) { |
301 |
free(tempbuf); |
302 |
tempbuf = NULL; |
303 |
tempbuflen = 0; |
304 |
} |
305 |
return(NULL); |
306 |
} |
307 |
if (len <= tempbuflen) /* big enough already? */ |
308 |
return(tempbuf); |
309 |
/* else free & reallocate */ |
310 |
if (tempbuflen) |
311 |
free(tempbuf); |
312 |
tempbuf = malloc(len); |
313 |
tempbuflen = len*(tempbuf != NULL); |
314 |
return(tempbuf); |
315 |
} |
316 |
|
317 |
|
318 |
int |
319 |
fwritecolrs( /* write out a colr scanline */ |
320 |
COLR *scanline, |
321 |
int len, |
322 |
FILE *fp |
323 |
) |
324 |
{ |
325 |
int i, j, beg, cnt = 1; |
326 |
int c2; |
327 |
|
328 |
if ((len < MINELEN) | (len > MAXELEN)) /* OOBs, write out flat */ |
329 |
return(fwrite((char *)scanline,sizeof(COLR),len,fp) - len); |
330 |
/* put magic header */ |
331 |
putc(2, fp); |
332 |
putc(2, fp); |
333 |
putc(len>>8, fp); |
334 |
putc(len&0xff, fp); |
335 |
/* put components seperately */ |
336 |
for (i = 0; i < 4; i++) { |
337 |
for (j = 0; j < len; j += cnt) { /* find next run */ |
338 |
for (beg = j; beg < len; beg += cnt) { |
339 |
for (cnt = 1; (cnt < 127) & (beg+cnt < len) && |
340 |
scanline[beg+cnt][i] == scanline[beg][i]; cnt++) |
341 |
; |
342 |
if (cnt >= MINRUN) |
343 |
break; /* long enough */ |
344 |
} |
345 |
if ((beg-j > 1) & (beg-j < MINRUN)) { |
346 |
c2 = j+1; |
347 |
while (scanline[c2++][i] == scanline[j][i]) |
348 |
if (c2 == beg) { /* short run */ |
349 |
putc(128+beg-j, fp); |
350 |
putc(scanline[j][i], fp); |
351 |
j = beg; |
352 |
break; |
353 |
} |
354 |
} |
355 |
while (j < beg) { /* write out non-run */ |
356 |
if ((c2 = beg-j) > 128) c2 = 128; |
357 |
putc(c2, fp); |
358 |
while (c2--) |
359 |
putc(scanline[j++][i], fp); |
360 |
} |
361 |
if (cnt >= MINRUN) { /* write out run */ |
362 |
putc(128+cnt, fp); |
363 |
putc(scanline[beg][i], fp); |
364 |
} else |
365 |
cnt = 0; |
366 |
} |
367 |
} |
368 |
return(ferror(fp) ? -1 : 0); |
369 |
} |
370 |
|
371 |
/* |
372 |
* An old-format scanline is either a stream of valid RGBE or XYZE real |
373 |
* pixels or at least one real pixel followed by some number of |
374 |
* invalid real pixels of the form (1,1,1,n), where n is a count. |
375 |
* These can themselves be repeated to create a multibyte repeat |
376 |
* count, with the least significant byte first (little-endian order.) |
377 |
* Repeat counts are limited by the size of an int; if a repetition |
378 |
* leads to an overrun, the rest of the the repetition will be |
379 |
* silently ignored. |
380 |
*/ |
381 |
static int |
382 |
oldreadcolrs( /* read in an old-style colr scanline */ |
383 |
COLR *scanline, |
384 |
int len, |
385 |
FILE *fp |
386 |
) |
387 |
{ |
388 |
int rshift = 0; |
389 |
int i; |
390 |
|
391 |
while (len > 0) { |
392 |
scanline[0][RED] = getc(fp); |
393 |
scanline[0][GRN] = getc(fp); |
394 |
scanline[0][BLU] = getc(fp); |
395 |
scanline[0][EXP] = i = getc(fp); |
396 |
if (i == EOF) |
397 |
return(-1); |
398 |
if (scanline[0][GRN] == 1 && |
399 |
(scanline[0][RED] == 1) & |
400 |
(scanline[0][BLU] == 1)) { |
401 |
i = scanline[0][EXP] << rshift; |
402 |
while (i--) { |
403 |
copycolr(scanline[0], scanline[-1]); |
404 |
if (--len <= 0) |
405 |
return(0); |
406 |
scanline++; |
407 |
} |
408 |
rshift += 8; |
409 |
} else { |
410 |
scanline++; |
411 |
len--; |
412 |
rshift = 0; |
413 |
} |
414 |
} |
415 |
return(0); |
416 |
} |
417 |
|
418 |
/* |
419 |
* There are two scanline formats: old and new. The old format |
420 |
* compresses runs of RGBE or XYZE four-byte real pixels; the new |
421 |
* format breaks the pixels into R, G, B, and E lines (or XYZE lines) |
422 |
* which are individually run-length encoded. |
423 |
* |
424 |
* An old-format scanline always begins with a valid real pixel; at |
425 |
* least one of the RGB (or XYZ) values will have its high-order bit |
426 |
* set. A new-format scanline begins with four bytes which are not a |
427 |
* valid real pixel: (2, 2, lenhigh, lenlow) where lenhigh is always |
428 |
* less than 128 and hence never has a high-order bit set. |
429 |
* |
430 |
* A new-format scanline is broken into its RGBE or XYZE components. |
431 |
* Each is output and run-length encoded separately so that a scanline |
432 |
* is broken into four records. In turn, each record is organized |
433 |
* into chunks of up to 128 characters, which begin with a count byte. |
434 |
* If the count byte is greater than 128, the following data byte is |
435 |
* repeated (count-128) times. If not, the count byte is followed by |
436 |
* that many data bytes. |
437 |
*/ |
438 |
int |
439 |
freadcolrs( /* read in an encoded colr scanline */ |
440 |
COLR *scanline, |
441 |
int len, |
442 |
FILE *fp |
443 |
) |
444 |
{ |
445 |
int i, j; |
446 |
int code, val; |
447 |
/* determine scanline type */ |
448 |
if (len <= 0) |
449 |
return(0); |
450 |
if ((i = getc(fp)) == EOF) |
451 |
return(-1); |
452 |
scanline[0][RED] = i; |
453 |
scanline[0][GRN] = getc(fp); |
454 |
scanline[0][BLU] = getc(fp); |
455 |
if ((i = getc(fp)) == EOF) |
456 |
return(-1); |
457 |
if ((scanline[0][RED] != 2) | (scanline[0][GRN] != 2) | |
458 |
(scanline[0][BLU] & 0x80)) { |
459 |
scanline[0][EXP] = i; |
460 |
return(oldreadcolrs(scanline+1, len-1, fp)); |
461 |
} |
462 |
if ((scanline[0][BLU]<<8 | i) != len) |
463 |
return(-1); /* length mismatch! */ |
464 |
/* read each component */ |
465 |
for (i = 0; i < 4; i++) |
466 |
for (j = 0; j < len; ) { |
467 |
if ((code = getc(fp)) == EOF) |
468 |
return(-1); |
469 |
if (code > 128) { /* run */ |
470 |
code &= 127; |
471 |
if ((val = getc(fp)) == EOF) |
472 |
return -1; |
473 |
if (j + code > len) |
474 |
return -1; /* overrun */ |
475 |
while (code--) |
476 |
scanline[j++][i] = val; |
477 |
} else { /* non-run */ |
478 |
if (j + code > len) |
479 |
return -1; /* overrun */ |
480 |
while (code--) { |
481 |
if ((val = getc(fp)) == EOF) |
482 |
return -1; |
483 |
scanline[j++][i] = val; |
484 |
} |
485 |
} |
486 |
} |
487 |
return(0); |
488 |
} |
489 |
|
490 |
|
491 |
/* read an nc-component common-exponent color scanline */ |
492 |
int |
493 |
freadscolrs(uby8 *scanline, int nc, int len, FILE *fp) |
494 |
{ |
495 |
if (fread(scanline, nc+1, len, fp) != len) |
496 |
return(-1); |
497 |
return(0); |
498 |
} |
499 |
|
500 |
|
501 |
/* write an common-exponent spectral color scanline */ |
502 |
int |
503 |
fwritescolrs(uby8 *sscanline, int nc, int len, FILE *fp) |
504 |
{ |
505 |
if (fwrite(sscanline, nc+1, len, fp) != len) |
506 |
return(-1); |
507 |
return(0); |
508 |
} |
509 |
|
510 |
|
511 |
int |
512 |
fwritescan( /* write out a scanline */ |
513 |
COLOR *scanline, |
514 |
int len, |
515 |
FILE *fp |
516 |
) |
517 |
{ |
518 |
COLR *clrscan; |
519 |
int n; |
520 |
COLR *sp; |
521 |
/* get scanline buffer */ |
522 |
if ((sp = (COLR *)tempbuffer(len*sizeof(COLR))) == NULL) |
523 |
return(-1); |
524 |
clrscan = sp; |
525 |
/* convert scanline */ |
526 |
n = len; |
527 |
while (n-- > 0) { |
528 |
setcolr(sp[0], scanline[0][RED], |
529 |
scanline[0][GRN], |
530 |
scanline[0][BLU]); |
531 |
scanline++; |
532 |
sp++; |
533 |
} |
534 |
return(fwritecolrs(clrscan, len, fp)); |
535 |
} |
536 |
|
537 |
|
538 |
int |
539 |
freadscan( /* read in a scanline */ |
540 |
COLOR *scanline, |
541 |
int len, |
542 |
FILE *fp |
543 |
) |
544 |
{ |
545 |
COLR *clrscan; |
546 |
|
547 |
if ((clrscan = (COLR *)tempbuffer(len*sizeof(COLR))) == NULL) |
548 |
return(-1); |
549 |
if (freadcolrs(clrscan, len, fp) < 0) |
550 |
return(-1); |
551 |
/* convert scanline */ |
552 |
colr_color(scanline[0], clrscan[0]); |
553 |
while (--len > 0) { |
554 |
scanline++; clrscan++; |
555 |
if (clrscan[0][GRN] == clrscan[-1][GRN] && |
556 |
(clrscan[0][RED] == clrscan[-1][RED]) & |
557 |
(clrscan[0][BLU] == clrscan[-1][BLU]) & |
558 |
(clrscan[0][EXP] == clrscan[-1][EXP])) |
559 |
copycolor(scanline[0], scanline[-1]); |
560 |
else |
561 |
colr_color(scanline[0], clrscan[0]); |
562 |
} |
563 |
return(0); |
564 |
} |
565 |
|
566 |
|
567 |
/* read an nc-component color scanline */ |
568 |
int |
569 |
freadsscan(COLORV *sscanline, int nc, int len, FILE *fp) |
570 |
{ |
571 |
uby8 *tscn = (uby8 *)tempbuffer((nc+1)*len); |
572 |
int i; |
573 |
|
574 |
if (tscn == NULL || freadscolrs(tscn, nc, len, fp) < 0) |
575 |
return(-1); |
576 |
for (i = len; i-- > 0; ) { |
577 |
scolr2scolor(sscanline, tscn, nc); |
578 |
sscanline += nc; |
579 |
tscn += nc+1; |
580 |
} |
581 |
return(0); |
582 |
} |
583 |
|
584 |
|
585 |
/* write an spectral color scanline (NCSAMP) */ |
586 |
int |
587 |
fwritesscan(COLORV *sscanline, int nc, int len, FILE *fp) |
588 |
{ |
589 |
uby8 *tscn = (uby8 *)tempbuffer((nc+1)*len); |
590 |
int i; |
591 |
|
592 |
if (tscn == NULL) |
593 |
return(-1); |
594 |
for (i = 0; i < len; i++) { |
595 |
scolor2scolr(tscn+i*(nc+1), sscanline, nc); |
596 |
sscanline += nc; |
597 |
} |
598 |
return(fwritescolrs(tscn, nc, len, fp)); |
599 |
} |
600 |
|
601 |
|
602 |
void |
603 |
setcolr( /* assign a short color value */ |
604 |
COLR clr, |
605 |
double r, |
606 |
double g, |
607 |
double b |
608 |
) |
609 |
{ |
610 |
double d; |
611 |
int e; |
612 |
|
613 |
d = r > g ? r : g; |
614 |
if (b > d) d = b; |
615 |
|
616 |
if (d <= 1e-32) { |
617 |
clr[RED] = clr[GRN] = clr[BLU] = 0; |
618 |
clr[EXP] = 0; |
619 |
return; |
620 |
} |
621 |
|
622 |
d = frexp(d, &e) * 256.0 / d; |
623 |
|
624 |
clr[RED] = (r > 0) * (int)(r*d); |
625 |
clr[GRN] = (g > 0) * (int)(g*d); |
626 |
clr[BLU] = (b > 0) * (int)(b*d); |
627 |
clr[EXP] = e + COLXS; |
628 |
} |
629 |
|
630 |
|
631 |
void |
632 |
colr_color( /* convert short to float color */ |
633 |
COLOR col, |
634 |
COLR clr |
635 |
) |
636 |
{ |
637 |
double f; |
638 |
|
639 |
if (clr[EXP] == 0) { |
640 |
col[RED] = col[GRN] = col[BLU] = 0.0; |
641 |
return; |
642 |
} |
643 |
f = ldexp(1.0, (int)clr[EXP]-(COLXS+8)); |
644 |
col[RED] = (clr[RED] + 0.5)*f; |
645 |
col[GRN] = (clr[GRN] + 0.5)*f; |
646 |
col[BLU] = (clr[BLU] + 0.5)*f; |
647 |
} |
648 |
|
649 |
|
650 |
int |
651 |
bigdiff( /* c1 delta c2 > md? */ |
652 |
COLOR c1, |
653 |
COLOR c2, |
654 |
double md |
655 |
) |
656 |
{ |
657 |
int i; |
658 |
|
659 |
for (i = 0; i < 3; i++) |
660 |
if ((colval(c1,i)-colval(c2,i) > md*colval(c2,i)) | |
661 |
(colval(c2,i)-colval(c1,i) > md*colval(c1,i))) |
662 |
return(1); |
663 |
return(0); |
664 |
} |
665 |
|
666 |
|
667 |
int |
668 |
sbigsdiff( /* sc1 delta sc2 > md? */ |
669 |
SCOLOR c1, |
670 |
SCOLOR c2, |
671 |
double md |
672 |
) |
673 |
{ |
674 |
int i = NCSAMP; |
675 |
|
676 |
while (i--) |
677 |
if ((c1[i]-c2[i] > md*c2[i]) | (c2[i]-c1[i] > md*c1[i])) |
678 |
return(1); |
679 |
return(0); |
680 |
} |