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/* Copyright (c) 1997 Regents of the University of California */ |
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|
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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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/* |
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* Convert colors and spectral ranges. |
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*/ |
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|
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#include "color.h" |
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|
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#define CEPS 1e-7 /* color epsilon */ |
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|
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|
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RGBPRIMS stdprims = STDPRIMS; /* standard primary chromaticities */ |
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|
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COLOR cblack = BLKCOLOR; /* global black color */ |
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COLOR cwhite = WHTCOLOR; /* global white color */ |
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|
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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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|
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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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|
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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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|
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COLORMAT xyz2rgbmat = { /* XYZ to RGB */ |
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{(CIE_y_g - CIE_y_b - CIE_x_b*CIE_y_g + CIE_y_b*CIE_x_g)/CIE_C_rD, |
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(CIE_x_b - CIE_x_g - CIE_x_b*CIE_y_g + CIE_x_g*CIE_y_b)/CIE_C_rD, |
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(CIE_x_g*CIE_y_b - CIE_x_b*CIE_y_g)/CIE_C_rD}, |
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{(CIE_y_b - CIE_y_r - CIE_y_b*CIE_x_r + CIE_y_r*CIE_x_b)/CIE_C_gD, |
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(CIE_x_r - CIE_x_b - CIE_x_r*CIE_y_b + CIE_x_b*CIE_y_r)/CIE_C_gD, |
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(CIE_x_b*CIE_y_r - CIE_x_r*CIE_y_b)/CIE_C_gD}, |
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{(CIE_y_r - CIE_y_g - CIE_y_r*CIE_x_g + CIE_y_g*CIE_x_r)/CIE_C_bD, |
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(CIE_x_g - CIE_x_r - CIE_x_g*CIE_y_r + CIE_x_r*CIE_y_g)/CIE_C_bD, |
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(CIE_x_r*CIE_y_g - CIE_x_g*CIE_y_r)/CIE_C_bD} |
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}; |
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|
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COLORMAT rgb2xyzmat = { /* RGB to XYZ */ |
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{CIE_x_r*CIE_C_rD/CIE_D,CIE_x_g*CIE_C_gD/CIE_D,CIE_x_b*CIE_C_bD/CIE_D}, |
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{CIE_y_r*CIE_C_rD/CIE_D,CIE_y_g*CIE_C_gD/CIE_D,CIE_y_b*CIE_C_bD/CIE_D}, |
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{(1.-CIE_x_r-CIE_y_r)*CIE_C_rD/CIE_D, |
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(1.-CIE_x_g-CIE_y_g)*CIE_C_gD/CIE_D, |
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(1.-CIE_x_b-CIE_y_b)*CIE_C_bD/CIE_D} |
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}; |
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|
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|
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|
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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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|
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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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|
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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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|
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s -= STARTWL; |
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if (s < 0) |
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s = 0; |
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|
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e -= STARTWL; |
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if (e <= s) { |
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col[CIEX] = col[CIEY] = col[CIEZ] = 0.0; |
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return; |
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} |
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if (e >= INCWL*(NINC - 1)) |
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e = INCWL*(NINC - 1) - 1; |
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|
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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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|
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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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|
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col[CIEX] = (col[CIEX] + 0.5) * (1./(256*INCWL)); |
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col[CIEY] = (col[CIEY] + 0.5) * (1./(256*INCWL)); |
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col[CIEZ] = (col[CIEZ] + 0.5) * (1./(256*INCWL)); |
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} |
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|
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|
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cie_rgb(rgb, xyz) /* convert CIE color to standard RGB */ |
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COLOR rgb, xyz; |
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{ |
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colortrans(rgb, xyz2rgbmat, xyz); |
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clipgamut(rgb, xyz[CIEY], CGAMUT_LOWER, cblack, cwhite); |
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} |
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|
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|
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int |
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clipgamut(col, brt, gamut, lower, upper) /* clip to gamut cube */ |
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COLOR col; |
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double brt; |
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int gamut; |
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COLOR lower, upper; |
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{ |
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int rflags = 0; |
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double brtmin, brtmax, v, vv; |
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COLOR cgry; |
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register int i; |
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/* check for no check */ |
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if (gamut == 0) return(0); |
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/* check brightness limits */ |
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brtmin = 1./3.*(lower[0]+lower[1]+lower[2]); |
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if (gamut & CGAMUT_LOWER && brt < brtmin) { |
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copycolor(col, lower); |
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return(CGAMUT_LOWER); |
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} |
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brtmax = 1./3.*(upper[0]+upper[1]+upper[2]); |
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if (gamut & CGAMUT_UPPER && brt > brtmax) { |
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copycolor(col, upper); |
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return(CGAMUT_UPPER); |
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} |
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/* compute equivalent grey */ |
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v = (brt - brtmin)/(brtmax - brtmin); |
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for (i = 0; i < 3; i++) |
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cgry[i] = v*upper[i] + (1.-v)*lower[i]; |
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vv = 1.; /* check each limit */ |
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for (i = 0; i < 3; i++) |
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if (gamut & CGAMUT_LOWER && col[i] < lower[i]) { |
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v = (lower[i]+CEPS - cgry[i])/(col[i] - cgry[i]); |
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if (v < vv) vv = v; |
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rflags |= CGAMUT_LOWER; |
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} else if (gamut & CGAMUT_UPPER && col[i] > upper[i]) { |
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v = (upper[i]-CEPS - cgry[i])/(col[i] - cgry[i]); |
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if (v < vv) vv = v; |
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rflags |= CGAMUT_UPPER; |
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} |
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if (rflags) /* desaturate to cube face */ |
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for (i = 0; i < 3; i++) |
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col[i] = vv*col[i] + (1.-vv)*cgry[i]; |
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return(rflags); |
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} |
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|
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|
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colortrans(c2, mat, c1) /* convert c1 by mat and put into c2 */ |
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register COLORMAT mat; |
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register COLOR c1, c2; |
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{ |
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COLOR cout; |
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|
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cout[0] = mat[0][0]*c1[0] + mat[0][1]*c1[1] + mat[0][2]*c1[2]; |
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cout[1] = mat[1][0]*c1[0] + mat[1][1]*c1[1] + mat[1][2]*c1[2]; |
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cout[2] = mat[2][0]*c1[0] + mat[2][1]*c1[1] + mat[2][2]*c1[2]; |
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|
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copycolor(c2, cout); |
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} |
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|
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|
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multcolormat(m3, m2, m1) /* multiply m1 by m2 and put into m3 */ |
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COLORMAT m1, m2, m3; /* m3 can be either m1 or m2 w/o harm */ |
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{ |
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COLORMAT mt; |
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register int i, j; |
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|
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for (i = 0; i < 3; i++) |
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for (j = 0; j < 3; j++) |
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mt[i][j] = m1[i][0]*m2[0][j] + |
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m1[i][1]*m2[1][j] + |
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m1[i][2]*m2[2][j] ; |
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cpcolormat(m3, mt); |
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} |
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|
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|
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compxyz2rgbmat(mat, pr) /* compute conversion from CIE to RGB space */ |
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COLORMAT mat; |
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register RGBPRIMS pr; |
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{ |
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double C_rD, C_gD, C_bD; |
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|
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if (pr == stdprims) { /* can use xyz2rgbmat */ |
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cpcolormat(mat, xyz2rgbmat); |
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return; |
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} |
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C_rD = (1./pr[WHT][CIEY]) * |
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( pr[WHT][CIEX]*(pr[GRN][CIEY] - pr[BLU][CIEY]) - |
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pr[WHT][CIEY]*(pr[GRN][CIEX] - pr[BLU][CIEX]) + |
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pr[GRN][CIEX]*pr[BLU][CIEY] - pr[BLU][CIEX]*pr[GRN][CIEY] ) ; |
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C_gD = (1./pr[WHT][CIEY]) * |
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( pr[WHT][CIEX]*(pr[BLU][CIEY] - pr[RED][CIEY]) - |
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pr[WHT][CIEY]*(pr[BLU][CIEX] - pr[RED][CIEX]) - |
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pr[RED][CIEX]*pr[BLU][CIEY] + pr[BLU][CIEX]*pr[RED][CIEY] ) ; |
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C_bD = (1./pr[WHT][CIEY]) * |
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( pr[WHT][CIEX]*(pr[RED][CIEY] - pr[GRN][CIEY]) - |
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pr[WHT][CIEY]*(pr[RED][CIEX] - pr[GRN][CIEX]) + |
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pr[RED][CIEX]*pr[GRN][CIEY] - pr[GRN][CIEX]*pr[RED][CIEY] ) ; |
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|
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mat[0][0] = (pr[GRN][CIEY] - pr[BLU][CIEY] - |
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pr[BLU][CIEX]*pr[GRN][CIEY] + |
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pr[BLU][CIEY]*pr[GRN][CIEX])/C_rD ; |
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mat[0][1] = (pr[BLU][CIEX] - pr[GRN][CIEX] - |
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pr[BLU][CIEX]*pr[GRN][CIEY] + |
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pr[GRN][CIEX]*pr[BLU][CIEY])/C_rD ; |
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mat[0][2] = (pr[GRN][CIEX]*pr[BLU][CIEY] - |
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pr[BLU][CIEX]*pr[GRN][CIEY])/C_rD ; |
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mat[1][0] = (pr[BLU][CIEY] - pr[RED][CIEY] - |
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pr[BLU][CIEY]*pr[RED][CIEX] + |
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pr[RED][CIEY]*pr[BLU][CIEX])/C_gD ; |
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mat[1][1] = (pr[RED][CIEX] - pr[BLU][CIEX] - |
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pr[RED][CIEX]*pr[BLU][CIEY] + |
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pr[BLU][CIEX]*pr[RED][CIEY])/C_gD ; |
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mat[1][2] = (pr[BLU][CIEX]*pr[RED][CIEY] - |
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pr[RED][CIEX]*pr[BLU][CIEY])/C_gD ; |
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mat[2][0] = (pr[RED][CIEY] - pr[GRN][CIEY] - |
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pr[RED][CIEY]*pr[GRN][CIEX] + |
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pr[GRN][CIEY]*pr[RED][CIEX])/C_bD ; |
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mat[2][1] = (pr[GRN][CIEX] - pr[RED][CIEX] - |
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pr[GRN][CIEX]*pr[RED][CIEY] + |
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pr[RED][CIEX]*pr[GRN][CIEY])/C_bD ; |
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mat[2][2] = (pr[RED][CIEX]*pr[GRN][CIEY] - |
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pr[GRN][CIEX]*pr[RED][CIEY])/C_bD ; |
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} |
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|
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|
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comprgb2xyzmat(mat, pr) /* compute conversion from RGB to CIE space */ |
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COLORMAT mat; |
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register RGBPRIMS pr; |
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{ |
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double C_rD, C_gD, C_bD, D; |
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|
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if (pr == stdprims) { /* can use rgb2xyzmat */ |
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cpcolormat(mat, rgb2xyzmat); |
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return; |
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} |
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C_rD = (1./pr[WHT][CIEY]) * |
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( pr[WHT][CIEX]*(pr[GRN][CIEY] - pr[BLU][CIEY]) - |
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pr[WHT][CIEY]*(pr[GRN][CIEX] - pr[BLU][CIEX]) + |
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pr[GRN][CIEX]*pr[BLU][CIEY] - pr[BLU][CIEX]*pr[GRN][CIEY] ) ; |
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C_gD = (1./pr[WHT][CIEY]) * |
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( pr[WHT][CIEX]*(pr[BLU][CIEY] - pr[RED][CIEY]) - |
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pr[WHT][CIEY]*(pr[BLU][CIEX] - pr[RED][CIEX]) - |
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pr[RED][CIEX]*pr[BLU][CIEY] + pr[BLU][CIEX]*pr[RED][CIEY] ) ; |
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C_bD = (1./pr[WHT][CIEY]) * |
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( pr[WHT][CIEX]*(pr[RED][CIEY] - pr[GRN][CIEY]) - |
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pr[WHT][CIEY]*(pr[RED][CIEX] - pr[GRN][CIEX]) + |
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pr[RED][CIEX]*pr[GRN][CIEY] - pr[GRN][CIEX]*pr[RED][CIEY] ) ; |
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D = pr[RED][CIEX]*(pr[GRN][CIEY] - pr[BLU][CIEY]) + |
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pr[GRN][CIEX]*(pr[BLU][CIEY] - pr[RED][CIEY]) + |
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pr[BLU][CIEX]*(pr[RED][CIEY] - pr[GRN][CIEY]) ; |
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mat[0][0] = pr[RED][CIEX]*C_rD/D; |
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mat[0][1] = pr[GRN][CIEX]*C_gD/D; |
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mat[0][2] = pr[BLU][CIEX]*C_bD/D; |
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mat[1][0] = pr[RED][CIEY]*C_rD/D; |
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mat[1][1] = pr[GRN][CIEY]*C_gD/D; |
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mat[1][2] = pr[BLU][CIEY]*C_bD/D; |
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mat[2][0] = (1.-pr[RED][CIEX]-pr[RED][CIEY])*C_rD/D; |
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mat[2][1] = (1.-pr[GRN][CIEX]-pr[GRN][CIEY])*C_gD/D; |
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mat[2][2] = (1.-pr[BLU][CIEX]-pr[BLU][CIEY])*C_bD/D; |
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} |
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|
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|
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comprgb2rgbmat(mat, pr1, pr2) /* compute conversion from RGB1 to RGB2 */ |
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COLORMAT mat; |
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RGBPRIMS pr1, pr2; |
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{ |
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COLORMAT pr1toxyz, xyztopr2; |
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|
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if (pr1 == pr2) { |
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mat[0][0] = mat[1][1] = mat[2][2] = 1.0; |
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mat[0][1] = mat[0][2] = mat[1][0] = |
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mat[1][2] = mat[2][0] = mat[2][1] = 0.0; |
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return; |
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} |
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comprgb2xyzmat(pr1toxyz, pr1); |
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compxyz2rgbmat(xyztopr2, pr2); |
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/* combine transforms */ |
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multcolormat(mat, pr1toxyz, xyztopr2); |
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} |
