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#ifndef lint |
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static const char RCSid[] = "$Id: spec_rgb.c,v 2.16 2007/10/08 18:07:55 greg Exp $"; |
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#endif |
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/* |
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* Convert colors and spectral ranges. |
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* Added von Kries white-balance calculations 10/01 (GW). |
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* |
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* Externals declared in color.h |
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*/ |
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|
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#include "copyright.h" |
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|
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#include <stdio.h> |
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#include <string.h> |
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#include "color.h" |
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|
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#define CEPS 1e-4 /* color epsilon */ |
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|
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#define CEQ(v1,v2) ((v1) <= (v2)+CEPS && (v2) <= (v1)+CEPS) |
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|
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#define XYEQ(c1,c2) (CEQ((c1)[CIEX],(c2)[CIEX]) && CEQ((c1)[CIEY],(c2)[CIEY])) |
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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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float xyneu[2] = {1./3., 1./3.}; /* neutral xy chromaticities */ |
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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 (no white balance) */ |
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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 (no white balance) */ |
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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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COLORMAT vkmat = { /* Sharp primary matrix */ |
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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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|
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COLORMAT ivkmat = { /* inverse Sharp primary matrix */ |
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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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|
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|
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void |
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spec_rgb( /* compute RGB color from spectral range */ |
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COLOR col, |
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int s, |
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int e |
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) |
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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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void |
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spec_cie( /* compute a color from a spectral range */ |
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COLOR col, /* returned color */ |
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int s, /* starting and ending wavelengths */ |
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int e |
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) |
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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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void |
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cie_rgb( /* convert CIE color to standard RGB */ |
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COLOR rgb, |
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COLOR xyz |
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) |
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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( /* 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, |
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COLOR upper |
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) |
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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] - 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] - 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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void |
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colortrans( /* convert c1 by mat and put into c2 */ |
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register COLOR c2, |
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register COLORMAT mat, |
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register COLOR c1 |
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) |
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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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void |
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multcolormat( /* multiply m1 by m2 and put into m3 */ |
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COLORMAT m3, /* m3 can be either m1 or m2 w/o harm */ |
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COLORMAT m2, |
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COLORMAT m1 |
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) |
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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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int |
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colorprimsOK( /* are color primaries reasonable? */ |
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RGBPRIMS pr |
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) |
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{ |
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int i; |
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|
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for (i = 0; i < 4; i++) { |
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if ((pr[i][CIEX] <= -CEPS) | (pr[i][CIEY] <= -CEPS)) |
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return(0); |
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if ((pr[i][CIEX] >= 1.+CEPS) | (pr[i][CIEY] >= 1.+CEPS)) |
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return(0); |
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if (pr[i][CIEX] + pr[i][CIEY] >= 1.+CEPS) |
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return(0); |
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} |
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return(1); |
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} |
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|
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|
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|
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int |
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compxyz2rgbmat( /* 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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{ |
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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(1); |
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} |
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if (CEQ(pr[WHT][CIEX],0.) | CEQ(pr[WHT][CIEY],0.)) |
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return(0); |
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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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if (CEQ(C_rD,0.)) |
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return(0); |
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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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if (CEQ(C_gD,0.)) |
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return(0); |
| 285 |
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]) + |
| 288 |
pr[RED][CIEX]*pr[GRN][CIEY] - pr[GRN][CIEX]*pr[RED][CIEY] ) ; |
| 289 |
if (CEQ(C_bD,0.)) |
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return(0); |
| 291 |
mat[0][0] = (pr[GRN][CIEY] - pr[BLU][CIEY] - |
| 292 |
pr[BLU][CIEX]*pr[GRN][CIEY] + |
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pr[BLU][CIEY]*pr[GRN][CIEX])/C_rD ; |
| 294 |
mat[0][1] = (pr[BLU][CIEX] - pr[GRN][CIEX] - |
| 295 |
pr[BLU][CIEX]*pr[GRN][CIEY] + |
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pr[GRN][CIEX]*pr[BLU][CIEY])/C_rD ; |
| 297 |
mat[0][2] = (pr[GRN][CIEX]*pr[BLU][CIEY] - |
| 298 |
pr[BLU][CIEX]*pr[GRN][CIEY])/C_rD ; |
| 299 |
mat[1][0] = (pr[BLU][CIEY] - pr[RED][CIEY] - |
| 300 |
pr[BLU][CIEY]*pr[RED][CIEX] + |
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pr[RED][CIEY]*pr[BLU][CIEX])/C_gD ; |
| 302 |
mat[1][1] = (pr[RED][CIEX] - pr[BLU][CIEX] - |
| 303 |
pr[RED][CIEX]*pr[BLU][CIEY] + |
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pr[BLU][CIEX]*pr[RED][CIEY])/C_gD ; |
| 305 |
mat[1][2] = (pr[BLU][CIEX]*pr[RED][CIEY] - |
| 306 |
pr[RED][CIEX]*pr[BLU][CIEY])/C_gD ; |
| 307 |
mat[2][0] = (pr[RED][CIEY] - pr[GRN][CIEY] - |
| 308 |
pr[RED][CIEY]*pr[GRN][CIEX] + |
| 309 |
pr[GRN][CIEY]*pr[RED][CIEX])/C_bD ; |
| 310 |
mat[2][1] = (pr[GRN][CIEX] - pr[RED][CIEX] - |
| 311 |
pr[GRN][CIEX]*pr[RED][CIEY] + |
| 312 |
pr[RED][CIEX]*pr[GRN][CIEY])/C_bD ; |
| 313 |
mat[2][2] = (pr[RED][CIEX]*pr[GRN][CIEY] - |
| 314 |
pr[GRN][CIEX]*pr[RED][CIEY])/C_bD ; |
| 315 |
return(1); |
| 316 |
} |
| 317 |
|
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|
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int |
| 320 |
comprgb2xyzmat( /* compute conversion from RGB to CIE space */ |
| 321 |
COLORMAT mat, |
| 322 |
register RGBPRIMS pr |
| 323 |
) |
| 324 |
{ |
| 325 |
double C_rD, C_gD, C_bD, D; |
| 326 |
|
| 327 |
if (pr == stdprims) { /* can use rgb2xyzmat */ |
| 328 |
cpcolormat(mat, rgb2xyzmat); |
| 329 |
return(1); |
| 330 |
} |
| 331 |
if (CEQ(pr[WHT][CIEX],0.) | CEQ(pr[WHT][CIEY],0.)) |
| 332 |
return(0); |
| 333 |
C_rD = (1./pr[WHT][CIEY]) * |
| 334 |
( pr[WHT][CIEX]*(pr[GRN][CIEY] - pr[BLU][CIEY]) - |
| 335 |
pr[WHT][CIEY]*(pr[GRN][CIEX] - pr[BLU][CIEX]) + |
| 336 |
pr[GRN][CIEX]*pr[BLU][CIEY] - pr[BLU][CIEX]*pr[GRN][CIEY] ) ; |
| 337 |
C_gD = (1./pr[WHT][CIEY]) * |
| 338 |
( pr[WHT][CIEX]*(pr[BLU][CIEY] - pr[RED][CIEY]) - |
| 339 |
pr[WHT][CIEY]*(pr[BLU][CIEX] - pr[RED][CIEX]) - |
| 340 |
pr[RED][CIEX]*pr[BLU][CIEY] + pr[BLU][CIEX]*pr[RED][CIEY] ) ; |
| 341 |
C_bD = (1./pr[WHT][CIEY]) * |
| 342 |
( pr[WHT][CIEX]*(pr[RED][CIEY] - pr[GRN][CIEY]) - |
| 343 |
pr[WHT][CIEY]*(pr[RED][CIEX] - pr[GRN][CIEX]) + |
| 344 |
pr[RED][CIEX]*pr[GRN][CIEY] - pr[GRN][CIEX]*pr[RED][CIEY] ) ; |
| 345 |
D = pr[RED][CIEX]*(pr[GRN][CIEY] - pr[BLU][CIEY]) + |
| 346 |
pr[GRN][CIEX]*(pr[BLU][CIEY] - pr[RED][CIEY]) + |
| 347 |
pr[BLU][CIEX]*(pr[RED][CIEY] - pr[GRN][CIEY]) ; |
| 348 |
if (CEQ(D,0.)) |
| 349 |
return(0); |
| 350 |
mat[0][0] = pr[RED][CIEX]*C_rD/D; |
| 351 |
mat[0][1] = pr[GRN][CIEX]*C_gD/D; |
| 352 |
mat[0][2] = pr[BLU][CIEX]*C_bD/D; |
| 353 |
mat[1][0] = pr[RED][CIEY]*C_rD/D; |
| 354 |
mat[1][1] = pr[GRN][CIEY]*C_gD/D; |
| 355 |
mat[1][2] = pr[BLU][CIEY]*C_bD/D; |
| 356 |
mat[2][0] = (1.-pr[RED][CIEX]-pr[RED][CIEY])*C_rD/D; |
| 357 |
mat[2][1] = (1.-pr[GRN][CIEX]-pr[GRN][CIEY])*C_gD/D; |
| 358 |
mat[2][2] = (1.-pr[BLU][CIEX]-pr[BLU][CIEY])*C_bD/D; |
| 359 |
return(1); |
| 360 |
} |
| 361 |
|
| 362 |
|
| 363 |
int |
| 364 |
comprgb2rgbmat( /* compute conversion from RGB1 to RGB2 */ |
| 365 |
COLORMAT mat, |
| 366 |
RGBPRIMS pr1, |
| 367 |
RGBPRIMS pr2 |
| 368 |
) |
| 369 |
{ |
| 370 |
COLORMAT pr1toxyz, xyztopr2; |
| 371 |
|
| 372 |
if (pr1 == pr2) { |
| 373 |
mat[0][0] = mat[1][1] = mat[2][2] = 1.0; |
| 374 |
mat[0][1] = mat[0][2] = mat[1][0] = |
| 375 |
mat[1][2] = mat[2][0] = mat[2][1] = 0.0; |
| 376 |
return(1); |
| 377 |
} |
| 378 |
if (!comprgb2xyzmat(pr1toxyz, pr1)) |
| 379 |
return(0); |
| 380 |
if (!compxyz2rgbmat(xyztopr2, pr2)) |
| 381 |
return(0); |
| 382 |
/* combine transforms */ |
| 383 |
multcolormat(mat, pr1toxyz, xyztopr2); |
| 384 |
return(1); |
| 385 |
} |
| 386 |
|
| 387 |
|
| 388 |
int |
| 389 |
compxyzWBmat( /* CIE von Kries transform from wht1 to wht2 */ |
| 390 |
COLORMAT mat, |
| 391 |
float wht1[2], |
| 392 |
float wht2[2] |
| 393 |
) |
| 394 |
{ |
| 395 |
COLOR cw1, cw2; |
| 396 |
if (XYEQ(wht1,wht2)) { |
| 397 |
mat[0][0] = mat[1][1] = mat[2][2] = 1.0; |
| 398 |
mat[0][1] = mat[0][2] = mat[1][0] = |
| 399 |
mat[1][2] = mat[2][0] = mat[2][1] = 0.0; |
| 400 |
return(1); |
| 401 |
} |
| 402 |
if (CEQ(wht1[CIEX],0.) | CEQ(wht1[CIEY],0.)) |
| 403 |
return(0); |
| 404 |
cw1[RED] = wht1[CIEX]/wht1[CIEY]; |
| 405 |
cw1[GRN] = 1.; |
| 406 |
cw1[BLU] = (1. - wht1[CIEX] - wht1[CIEY])/wht1[CIEY]; |
| 407 |
colortrans(cw1, vkmat, cw1); |
| 408 |
if (CEQ(wht2[CIEX],0.) | CEQ(wht2[CIEY],0.)) |
| 409 |
return(0); |
| 410 |
cw2[RED] = wht2[CIEX]/wht2[CIEY]; |
| 411 |
cw2[GRN] = 1.; |
| 412 |
cw2[BLU] = (1. - wht2[CIEX] - wht2[CIEY])/wht2[CIEY]; |
| 413 |
colortrans(cw2, vkmat, cw2); |
| 414 |
if (CEQ(cw1[RED],0.) | CEQ(cw1[GRN],0.) | CEQ(cw1[BLU],0.)) |
| 415 |
return(0); |
| 416 |
mat[0][0] = cw2[RED]/cw1[RED]; |
| 417 |
mat[1][1] = cw2[GRN]/cw1[GRN]; |
| 418 |
mat[2][2] = cw2[BLU]/cw1[BLU]; |
| 419 |
mat[0][1] = mat[0][2] = mat[1][0] = |
| 420 |
mat[1][2] = mat[2][0] = mat[2][1] = 0.0; |
| 421 |
multcolormat(mat, vkmat, mat); |
| 422 |
multcolormat(mat, mat, ivkmat); |
| 423 |
return(1); |
| 424 |
} |
| 425 |
|
| 426 |
|
| 427 |
int |
| 428 |
compxyz2rgbWBmat( /* von Kries conversion from CIE to RGB space */ |
| 429 |
COLORMAT mat, |
| 430 |
RGBPRIMS pr |
| 431 |
) |
| 432 |
{ |
| 433 |
COLORMAT wbmat; |
| 434 |
|
| 435 |
if (!compxyz2rgbmat(mat, pr)) |
| 436 |
return(0); |
| 437 |
if (XYEQ(pr[WHT],xyneu)) |
| 438 |
return(1); |
| 439 |
if (!compxyzWBmat(wbmat, xyneu, pr[WHT])) |
| 440 |
return(0); |
| 441 |
multcolormat(mat, wbmat, mat); |
| 442 |
return(1); |
| 443 |
} |
| 444 |
|
| 445 |
int |
| 446 |
comprgb2xyzWBmat( /* von Kries conversion from RGB to CIE space */ |
| 447 |
COLORMAT mat, |
| 448 |
RGBPRIMS pr |
| 449 |
) |
| 450 |
{ |
| 451 |
COLORMAT wbmat; |
| 452 |
|
| 453 |
if (!comprgb2xyzmat(mat, pr)) |
| 454 |
return(0); |
| 455 |
if (XYEQ(pr[WHT],xyneu)) |
| 456 |
return(1); |
| 457 |
if (!compxyzWBmat(wbmat, pr[WHT], xyneu)) |
| 458 |
return(0); |
| 459 |
multcolormat(mat, mat, wbmat); |
| 460 |
return(1); |
| 461 |
} |
| 462 |
|
| 463 |
int |
| 464 |
comprgb2rgbWBmat( /* von Kries conversion from RGB1 to RGB2 */ |
| 465 |
COLORMAT mat, |
| 466 |
RGBPRIMS pr1, |
| 467 |
RGBPRIMS pr2 |
| 468 |
) |
| 469 |
{ |
| 470 |
COLORMAT pr1toxyz, xyztopr2, wbmat; |
| 471 |
|
| 472 |
if (pr1 == pr2) { |
| 473 |
mat[0][0] = mat[1][1] = mat[2][2] = 1.0; |
| 474 |
mat[0][1] = mat[0][2] = mat[1][0] = |
| 475 |
mat[1][2] = mat[2][0] = mat[2][1] = 0.0; |
| 476 |
return(1); |
| 477 |
} |
| 478 |
if (!comprgb2xyzmat(pr1toxyz, pr1)) |
| 479 |
return(0); |
| 480 |
if (!compxyzWBmat(wbmat, pr1[WHT], pr2[WHT])) |
| 481 |
return(0); |
| 482 |
if (!compxyz2rgbmat(xyztopr2, pr2)) |
| 483 |
return(0); |
| 484 |
/* combine transforms */ |
| 485 |
multcolormat(mat, pr1toxyz, wbmat); |
| 486 |
multcolormat(mat, mat, xyztopr2); |
| 487 |
return(1); |
| 488 |
} |
