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#ifndef lint
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static const char RCSid[] = "$Id: ccolor.c,v 3.5 2012/06/26 17:59:16 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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/* Sharp primary matrix */
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float XYZtoSharp[3][3] = {
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{ 1.2694, -0.0988, -0.1706},
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{-0.8364, 1.8006, 0.0357},
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{ 0.0297, -0.0315, 1.0018}
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};
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/* inverse Sharp primary matrix */
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float XYZfromSharp[3][3] = {
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{ 0.8156, 0.0472, 0.1372},
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{ 0.3791, 0.5769, 0.0440},
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{-0.0123, 0.0167, 0.9955}
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};
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const C_COLOR c_dfcolor = C_DEFCOLOR;
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/* CIE 1931 Standard Observer curves */
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const C_COLOR c_x31 = { 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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const C_COLOR c_y31 = { 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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const C_COLOR c_z31 = { 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 const 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 const 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 const 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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/* convert to sharpened RGB color for low-error operations */
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void
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c_toSharpRGB(C_COLOR *cin, double cieY, float cout[3])
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{
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double xyz[3];
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c_ccvt(cin, C_CSXY);
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xyz[0] = cin->cx/cin->cy * cieY;
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xyz[1] = cieY;
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xyz[2] = (1. - cin->cx - cin->cy)/cin->cy * cieY;
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cout[0] = XYZtoSharp[0][0]*xyz[0] + XYZtoSharp[0][1]*xyz[1] +
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XYZtoSharp[0][2]*xyz[2];
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cout[1] = XYZtoSharp[1][0]*xyz[0] + XYZtoSharp[1][1]*xyz[1] +
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XYZtoSharp[1][2]*xyz[2];
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cout[2] = XYZtoSharp[2][0]*xyz[0] + XYZtoSharp[2][1]*xyz[1] +
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XYZtoSharp[2][2]*xyz[2];
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}
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/* convert back from sharpened RGB color */
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double
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c_fromSharpRGB(float cin[3], C_COLOR *cout)
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{
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double xyz[3], sf;
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xyz[0] = XYZfromSharp[0][0]*cin[0] + XYZfromSharp[0][1]*cin[1] +
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XYZfromSharp[0][2]*cin[2];
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xyz[1] = XYZfromSharp[1][0]*cin[0] + XYZfromSharp[1][1]*cin[1] +
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XYZfromSharp[1][2]*cin[2];
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xyz[2] = XYZfromSharp[2][0]*cin[0] + XYZfromSharp[2][1]*cin[1] +
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XYZfromSharp[2][2]*cin[2];
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sf = 1./(xyz[0] + xyz[1] + xyz[2]);
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cout->cx = xyz[0] * sf;
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cout->cy = xyz[1] * sf;
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cout->flags = C_CDXY|C_CSXY;
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return(xyz[1]);
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}
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/* assign arbitrary spectrum and return Y value */
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double
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c_sset(C_COLOR *clr, double wlmin, double wlmax, const float spec[], int nwl)
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{
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double yval, scale;
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float va[C_CNSS];
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int i, pos, n, imax, wl;
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double wl0, wlstep;
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double boxpos, boxstep;
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/* check arguments */
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if ((nwl <= 1) | (spec == NULL) | (wlmin >= C_CMAXWL) |
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(wlmax <= C_CMINWL) | (wlmin >= wlmax))
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return(0.);
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wlstep = (wlmax - wlmin)/(nwl-1);
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while (wlmin < C_CMINWL) {
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wlmin += wlstep;
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--nwl; ++spec;
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}
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while (wlmax > C_CMAXWL) {
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wlmax -= wlstep;
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--nwl;
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}
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if ((nwl <= 1) | (wlmin >= wlmax))
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return(0.);
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imax = nwl; /* box filter if necessary */
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boxpos = 0;
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boxstep = 1;
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if (wlstep < C_CWLI) {
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imax = (wlmax - wlmin)/C_CWLI + 1e-7;
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boxpos = (wlmin - C_CMINWL)/C_CWLI;
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boxstep = wlstep/C_CWLI;
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wlstep = C_CWLI;
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}
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scale = 0.; /* get values and maximum */
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yval = 0.;
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pos = 0;
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for (i = 0; i < imax; i++) {
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va[i] = 0.; n = 0;
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while (boxpos < i+.5 && pos < nwl) {
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va[i] += spec[pos++];
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n++;
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boxpos += boxstep;
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}
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if (n > 1)
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va[i] /= (double)n;
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if (va[i] > scale)
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scale = va[i];
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else if (va[i] < -scale)
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scale = -va[i];
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yval += va[i] * c_y31.ssamp[i];
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}
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if (scale <= 1e-7)
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return(0.);
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yval /= (double)c_y31.ssum;
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scale = C_CMAXV / scale;
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clr->ssum = 0; /* convert to our spacing */
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wl0 = wlmin;
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pos = 0;
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for (i = 0, wl = C_CMINWL; i < C_CNSS; i++, wl += C_CWLI)
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if ((wl < wlmin) | (wl > wlmax))
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clr->ssamp[i] = 0;
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else {
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while (wl0 + wlstep < wl+1e-7) {
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wl0 += wlstep;
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pos++;
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}
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if ((wl+1e-7 >= wl0) & (wl-1e-7 <= wl0))
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clr->ssamp[i] = scale*va[pos] + .5;
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else /* interpolate if necessary */
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clr->ssamp[i] = .5 + scale / wlstep *
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( va[pos]*(wl0+wlstep - wl) +
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va[pos+1]*(wl - wl0) );
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clr->ssum += clr->ssamp[i];
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}
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clr->flags = C_CDSPEC|C_CSSPEC;
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return(yval);
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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 += c_x31.ssamp[i] * clr->ssamp[i];
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y += c_y31.ssamp[i] * clr->ssamp[i];
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z += c_z31.ssamp[i] * clr->ssamp[i];
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}
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x /= (double)c_x31.ssum;
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y /= (double)c_y31.ssum;
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z /= (double)c_z31.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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}
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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 += c_y31.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*c_x31.eff + clr->cy*c_y31.eff +
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(1. - clr->cx - clr->cy)*c_z31.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 may 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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int i;
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if ((c1->flags|c2->flags) & C_CDSPEC) { /* spectral mixing */
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float cmix[C_CNSS];
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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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else 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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| 308 |
/* multiply two colors -- cres may be c1 or c2 */
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double
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c_cmult(C_COLOR *cres, C_COLOR *c1, double y1, C_COLOR *c2, double y2)
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{
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| 312 |
double yres;
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| 313 |
int i;
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| 314 |
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if ((c1->flags|c2->flags) & C_CDSPEC) {
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long cmix[C_CNSS], cmax = 0; /* spectral multiply */
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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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| 320 |
for (i = 0; i < C_CNSS; i++) {
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| 321 |
cmix[i] = c1->ssamp[i] * c2->ssamp[i];
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| 322 |
if (cmix[i] > cmax)
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cmax = cmix[i];
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| 324 |
else if (cmix[i] < -cmax)
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| 325 |
cmax = -cmix[i];
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}
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| 327 |
cmax /= C_CMAXV;
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| 328 |
if (!cmax) {
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*cres = c_dfcolor;
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| 330 |
return(0.);
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| 331 |
}
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| 332 |
cres->ssum = 0;
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for (i = 0; i < C_CNSS; i++)
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| 334 |
cres->ssum += cres->ssamp[i] = cmix[i] / cmax;
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| 335 |
cres->flags = C_CDSPEC|C_CSSPEC;
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| 336 |
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| 337 |
c_ccvt(cres, C_CSEFF); /* below is correct */
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| 338 |
yres = y1 * y2 * c_y31.ssum * C_CLPWM /
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| 339 |
(c1->eff*c1->ssum * c2->eff*c2->ssum) *
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| 340 |
cres->eff*( cres->ssum*(double)cmax +
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C_CNSS/2.0*(cmax-1) );
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| 342 |
} else {
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| 343 |
float rgb1[3], rgb2[3]; /* CIE xy multiply */
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| 344 |
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| 345 |
c_toSharpRGB(c1, y1, rgb1);
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| 346 |
c_toSharpRGB(c2, y2, rgb2);
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| 347 |
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rgb2[0] *= rgb1[0]; rgb2[1] *= rgb1[1]; rgb2[2] *= rgb1[2];
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| 349 |
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| 350 |
yres = c_fromSharpRGB(rgb2, cres);
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| 351 |
}
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| 352 |
return(yres);
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}
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| 354 |
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| 355 |
#define C1 3.741832e-16 /* W-m^2 */
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| 356 |
#define C2 1.4388e-2 /* m-K */
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| 357 |
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| 358 |
#define bbsp(l,t) (C1/((l)*(l)*(l)*(l)*(l)*(exp(C2/((t)*(l)))-1.)))
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| 359 |
#define bblm(t) (C2*0.2/(t))
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| 360 |
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| 361 |
/* set black body spectrum */
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| 362 |
int
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| 363 |
c_bbtemp(C_COLOR *clr, double tk)
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| 364 |
{
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| 365 |
double sf, wl;
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| 366 |
int i;
|
| 367 |
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| 368 |
if (tk < 1000)
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| 369 |
return(0);
|
| 370 |
wl = bblm(tk); /* scalefactor based on peak */
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| 371 |
if (wl < C_CMINWL*1e-9)
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| 372 |
wl = C_CMINWL*1e-9;
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| 373 |
else if (wl > C_CMAXWL*1e-9)
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| 374 |
wl = C_CMAXWL*1e-9;
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| 375 |
sf = C_CMAXV/bbsp(wl,tk);
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| 376 |
clr->ssum = 0;
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| 377 |
for (i = 0; i < C_CNSS; i++) {
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| 378 |
wl = (C_CMINWL + i*C_CWLI)*1e-9;
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| 379 |
clr->ssum += clr->ssamp[i] = sf*bbsp(wl,tk) + .5;
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| 380 |
}
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| 381 |
clr->flags = C_CDSPEC|C_CSSPEC;
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| 382 |
return(1);
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| 383 |
}
|
| 384 |
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| 385 |
#undef C1
|
| 386 |
#undef C2
|
| 387 |
#undef bbsp
|
| 388 |
#undef bblm
|
