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#ifndef lint
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static const char RCSid[] = "$Id: ccolor.c,v 1.3 2011/02/04 06:31:41 greg Exp $";
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#endif
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/*
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* Spectral color handling routines
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*/
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#include <stdio.h>
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#include <math.h>
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#include "ccolor.h"
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C_COLOR c_dfcolor = C_DEFCOLOR;
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/* CIE 1931 Standard Observer curves */
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static C_COLOR cie_xf = { 1, NULL, C_CDSPEC|C_CSSPEC|C_CSXY|C_CSEFF,
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{14,42,143,435,1344,2839,3483,3362,2908,1954,956,
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320,49,93,633,1655,2904,4334,5945,7621,9163,10263,
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10622,10026,8544,6424,4479,2835,1649,874,468,227,
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114,58,29,14,7,3,2,1,0}, 106836L, .467, .368, 362.230
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};
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static C_COLOR cie_yf = { 1, NULL, C_CDSPEC|C_CSSPEC|C_CSXY|C_CSEFF,
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{0,1,4,12,40,116,230,380,600,910,1390,2080,3230,
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5030,7100,8620,9540,9950,9950,9520,8700,7570,6310,
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5030,3810,2650,1750,1070,610,320,170,82,41,21,10,
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5,2,1,1,0,0}, 106856L, .398, .542, 493.525
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};
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static C_COLOR cie_zf = { 1, NULL, C_CDSPEC|C_CSSPEC|C_CSXY|C_CSEFF,
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{65,201,679,2074,6456,13856,17471,17721,16692,
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12876,8130,4652,2720,1582,782,422,203,87,39,21,17,
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11,8,3,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
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106770L, .147, .077, 54.363
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};
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/* Derived CIE 1931 Primaries (imaginary) */
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static C_COLOR cie_xp = { 1, NULL, C_CDSPEC|C_CSSPEC|C_CSXY,
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{-174,-198,-195,-197,-202,-213,-235,-272,-333,
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-444,-688,-1232,-2393,-4497,-6876,-6758,-5256,
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-3100,-815,1320,3200,4782,5998,6861,7408,7754,
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7980,8120,8199,8240,8271,8292,8309,8283,8469,
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8336,8336,8336,8336,8336,8336},
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127424L, 1., .0,
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};
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static C_COLOR cie_yp = { 1, NULL, C_CDSPEC|C_CSSPEC|C_CSXY,
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{-451,-431,-431,-430,-427,-417,-399,-366,-312,
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-204,57,691,2142,4990,8810,9871,9122,7321,5145,
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3023,1123,-473,-1704,-2572,-3127,-3474,-3704,
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-3846,-3927,-3968,-3999,-4021,-4038,-4012,-4201,
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-4066,-4066,-4066,-4066,-4066,-4066},
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-23035L, .0, 1.,
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};
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static C_COLOR cie_zp = { 1, NULL, C_CDSPEC|C_CSSPEC|C_CSXY,
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{4051,4054,4052,4053,4054,4056,4059,4064,4071,
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4074,4056,3967,3677,2933,1492,313,-440,-795,
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-904,-918,-898,-884,-869,-863,-855,-855,-851,
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-848,-847,-846,-846,-846,-845,-846,-843,-845,
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-845,-845,-845,-845,-845},
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36057L, .0, .0,
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};
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/* check if color is grey */
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int
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c_isgrey(C_COLOR *clr)
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{
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if (!(clr->flags & (C_CSXY|C_CSSPEC)))
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return(1); /* no settings == grey */
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c_ccvt(clr, C_CSXY);
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return(clr->cx >= .323 && clr->cx <= .343 &&
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clr->cy >= .323 && clr->cy <= .343);
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}
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/* convert color representations */
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void
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c_ccvt(C_COLOR *clr, int fl)
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{
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double x, y, z;
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int i;
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fl &= ~clr->flags; /* ignore what's done */
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if (!fl) /* everything's done! */
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return;
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if (!(clr->flags & (C_CSXY|C_CSSPEC))) {
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*clr = c_dfcolor; /* nothing was set! */
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return;
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}
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if (fl & C_CSXY) { /* cspec -> cxy */
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x = y = z = 0.;
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for (i = 0; i < C_CNSS; i++) {
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x += cie_xf.ssamp[i] * clr->ssamp[i];
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y += cie_yf.ssamp[i] * clr->ssamp[i];
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z += cie_zf.ssamp[i] * clr->ssamp[i];
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}
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x /= (double)cie_xf.ssum;
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y /= (double)cie_yf.ssum;
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z /= (double)cie_zf.ssum;
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z += x + y;
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clr->cx = x / z;
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clr->cy = y / z;
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clr->flags |= C_CSXY;
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} else if (fl & C_CSSPEC) { /* cxy -> cspec */
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x = clr->cx;
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y = clr->cy;
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z = 1. - x - y;
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clr->ssum = 0;
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for (i = 0; i < C_CNSS; i++) {
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clr->ssamp[i] = x*cie_xp.ssamp[i] + y*cie_yp.ssamp[i]
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+ z*cie_zp.ssamp[i] + .5;
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if (clr->ssamp[i] < 0) /* out of gamut! */
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clr->ssamp[i] = 0;
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else
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clr->ssum += clr->ssamp[i];
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}
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clr->flags |= C_CSSPEC;
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}
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if (fl & C_CSEFF) { /* compute efficacy */
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if (clr->flags & C_CSSPEC) { /* from spectrum */
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y = 0.;
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for (i = 0; i < C_CNSS; i++)
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y += cie_yf.ssamp[i] * clr->ssamp[i];
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clr->eff = C_CLPWM * y / clr->ssum;
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} else /* clr->flags & C_CSXY */ { /* from (x,y) */
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clr->eff = clr->cx*cie_xf.eff + clr->cy*cie_yf.eff +
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(1. - clr->cx - clr->cy)*cie_zf.eff;
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}
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clr->flags |= C_CSEFF;
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}
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}
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/* mix two colors according to weights given -- cres can be c1 or c2 */
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void
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c_cmix(C_COLOR *cres, double w1, C_COLOR *c1, double w2, C_COLOR *c2)
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{
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double scale;
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float cmix[C_CNSS];
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int i;
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if ((c1->flags|c2->flags) & C_CDSPEC) { /* spectral mixing */
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c_ccvt(c1, C_CSSPEC|C_CSEFF);
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c_ccvt(c2, C_CSSPEC|C_CSEFF);
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w1 /= c1->eff*c1->ssum;
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w2 /= c2->eff*c2->ssum;
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scale = 0.;
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for (i = 0; i < C_CNSS; i++) {
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cmix[i] = w1*c1->ssamp[i] + w2*c2->ssamp[i];
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if (cmix[i] > scale)
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scale = cmix[i];
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}
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scale = C_CMAXV / scale;
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cres->ssum = 0;
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for (i = 0; i < C_CNSS; i++)
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cres->ssum += cres->ssamp[i] = scale*cmix[i] + .5;
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cres->flags = C_CDSPEC|C_CSSPEC;
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} else { /* CIE xy mixing */
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c_ccvt(c1, C_CSXY);
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c_ccvt(c2, C_CSXY);
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w1 *= c2->cy;
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w2 *= c1->cy;
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scale = w1 + w2;
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if (scale == 0.) {
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*cres = c_dfcolor;
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return;
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}
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scale = 1. / scale;
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cres->cx = (w1*c1->cx + w2*c2->cx) * scale;
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cres->cy = (w1*c1->cy + w2*c2->cy) * scale;
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cres->flags = C_CDXY|C_CSXY;
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}
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}
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#define C1 3.741832e-16 /* W-m^2 */
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#define C2 1.4388e-2 /* m-K */
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#define bbsp(l,t) (C1/((l)*(l)*(l)*(l)*(l)*(exp(C2/((t)*(l)))-1.)))
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#define bblm(t) (C2/5./(t))
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/* set black body spectrum */
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int
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c_bbtemp(C_COLOR *clr, double tk)
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{
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double sf, wl;
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int i;
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if (tk < 1000)
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return(0);
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wl = bblm(tk); /* scalefactor based on peak */
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if (wl < C_CMINWL*1e-9)
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wl = C_CMINWL*1e-9;
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else if (wl > C_CMAXWL*1e-9)
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wl = C_CMAXWL*1e-9;
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sf = C_CMAXV/bbsp(wl,tk);
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clr->ssum = 0;
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for (i = 0; i < C_CNSS; i++) {
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wl = (C_CMINWL + i*C_CWLI)*1e-9;
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clr->ssum += clr->ssamp[i] = sf*bbsp(wl,tk) + .5;
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}
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clr->flags = C_CDSPEC|C_CSSPEC;
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return(1);
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}
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#undef C1
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#undef C2
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#undef bbsp
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#undef bblm
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