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greg |
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/* Copyright (c) 1990 Regents of the University of California */
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greg |
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#ifndef lint
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static char SCCSid[] = "$SunId$ LBL";
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#endif
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/*
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* Convert colors and spectral ranges.
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*/
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#include "color.h"
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/*
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* The following table contains the CIE tristimulus integrals
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* for X, Y, and Z. The table is cumulative, so that
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* each color coordinate integrates to 1.
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*/
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#define STARTWL 380 /* starting wavelength (nanometers) */
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#define INCWL 10 /* wavelength increment */
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#define NINC 40 /* # of values */
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static BYTE chroma[3][NINC] = {
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{ /* X */
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0, 0, 0, 2, 6, 13, 22, 30, 36, 41,
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42, 43, 43, 44, 46, 52, 60, 71, 87, 106,
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128, 153, 178, 200, 219, 233, 243, 249, 252, 254,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255
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}, { /* Y */
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0, 0, 0, 0, 0, 1, 2, 4, 7, 11,
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17, 24, 34, 48, 64, 84, 105, 127, 148, 169,
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188, 205, 220, 232, 240, 246, 250, 253, 254, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255
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}, { /* Z */
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0, 0, 2, 10, 32, 66, 118, 153, 191, 220,
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237, 246, 251, 253, 254, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255
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}
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};
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greg |
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#ifdef NTSC
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greg |
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static float xyz2rgbmat[3][3] = { /* XYZ to RGB (NTSC) */
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greg |
2.2 |
{1.73, -.48, -.26},
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{-.81, 1.65, -.02},
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{.08, -.17, 1.28}
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greg |
1.2 |
};
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#else
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static float xyz2rgbmat[3][3] = { /* XYZ to RGB (color monitor) */
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greg |
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{2.739, -1.145, -.424},
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{-1.119, 2.029, .033},
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{.138, -.333, 1.105}
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greg |
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};
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#endif
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greg |
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greg |
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greg |
1.1 |
spec_rgb(col, s, e) /* compute RGB color from spectral range */
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COLOR col;
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int s, e;
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{
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COLOR ciecolor;
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spec_cie(ciecolor, s, e);
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cie_rgb(col, ciecolor);
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}
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spec_cie(col, s, e) /* compute a color from a spectral range */
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COLOR col; /* returned color */
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int s, e; /* starting and ending wavelengths */
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{
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register int i, d, r;
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s -= STARTWL;
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if (s < 0)
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s = 0;
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e -= STARTWL;
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greg |
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if (e <= s) {
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col[RED] = col[GRN] = col[BLU] = 0.0;
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return;
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}
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greg |
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if (e >= INCWL*(NINC - 1))
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e = INCWL*(NINC - 1) - 1;
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d = e / INCWL; /* interpolate values */
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r = e % INCWL;
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for (i = 0; i < 3; i++)
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col[i] = chroma[i][d]*(INCWL - r) + chroma[i][d + 1]*r;
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d = s / INCWL;
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r = s % INCWL;
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for (i = 0; i < 3; i++)
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col[i] -= chroma[i][d]*(INCWL - r) - chroma[i][d + 1]*r;
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col[RED] = (col[RED] + 0.5) / (256*INCWL);
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col[GRN] = (col[GRN] + 0.5) / (256*INCWL);
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col[BLU] = (col[BLU] + 0.5) / (256*INCWL);
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}
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greg |
1.3 |
cie_rgb(rgbcolor, ciecolor) /* convert CIE to RGB */
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greg |
1.1 |
register COLOR rgbcolor, ciecolor;
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{
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register int i;
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for (i = 0; i < 3; i++) {
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greg |
1.2 |
rgbcolor[i] = xyz2rgbmat[i][0]*ciecolor[0] +
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xyz2rgbmat[i][1]*ciecolor[1] +
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xyz2rgbmat[i][2]*ciecolor[2] ;
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greg |
1.1 |
if (rgbcolor[i] < 0.0)
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rgbcolor[i] = 0.0;
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}
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}
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