//--------------------------------------------------------------------------------- // // Little Color Management System // Copyright (c) 1998-2020 Marti Maria Saguer // // Permission is hereby granted, free of charge, to any person obtaining // a copy of this software and associated documentation files (the "Software"), // to deal in the Software without restriction, including without limitation // the rights to use, copy, modify, merge, publish, distribute, sublicense, // and/or sell copies of the Software, and to permit persons to whom the Software // is furnished to do so, subject to the following conditions: // // The above copyright notice and this permission notice shall be included in // all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO // THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. // //--------------------------------------------------------------------------------- // #include "lcms2_internal.h" // D50 - Widely used const cmsCIEXYZ* CMSEXPORT cmsD50_XYZ(void) { static cmsCIEXYZ D50XYZ = {cmsD50X, cmsD50Y, cmsD50Z}; return &D50XYZ; } const cmsCIExyY* CMSEXPORT cmsD50_xyY(void) { static cmsCIExyY D50xyY; cmsXYZ2xyY(&D50xyY, cmsD50_XYZ()); return &D50xyY; } // Obtains WhitePoint from Temperature cmsBool CMSEXPORT cmsWhitePointFromTemp(cmsCIExyY* WhitePoint, cmsFloat64Number TempK) { cmsFloat64Number x, y; cmsFloat64Number T, T2, T3; // cmsFloat64Number M1, M2; _cmsAssert(WhitePoint != NULL); T = TempK; T2 = T*T; // Square T3 = T2*T; // Cube // For correlated color temperature (T) between 4000K and 7000K: if (T >= 4000. && T <= 7000.) { x = -4.6070*(1E9/T3) + 2.9678*(1E6/T2) + 0.09911*(1E3/T) + 0.244063; } else // or for correlated color temperature (T) between 7000K and 25000K: if (T > 7000.0 && T <= 25000.0) { x = -2.0064*(1E9/T3) + 1.9018*(1E6/T2) + 0.24748*(1E3/T) + 0.237040; } else { cmsSignalError(0, cmsERROR_RANGE, "cmsWhitePointFromTemp: invalid temp"); return FALSE; } // Obtain y(x) y = -3.000*(x*x) + 2.870*x - 0.275; // wave factors (not used, but here for futures extensions) // M1 = (-1.3515 - 1.7703*x + 5.9114 *y)/(0.0241 + 0.2562*x - 0.7341*y); // M2 = (0.0300 - 31.4424*x + 30.0717*y)/(0.0241 + 0.2562*x - 0.7341*y); WhitePoint -> x = x; WhitePoint -> y = y; WhitePoint -> Y = 1.0; return TRUE; } typedef struct { cmsFloat64Number mirek; // temp (in microreciprocal kelvin) cmsFloat64Number ut; // u coord of intersection w/ blackbody locus cmsFloat64Number vt; // v coord of intersection w/ blackbody locus cmsFloat64Number tt; // slope of ISOTEMPERATURE. line } ISOTEMPERATURE; static const ISOTEMPERATURE isotempdata[] = { // {Mirek, Ut, Vt, Tt } {0, 0.18006, 0.26352, -0.24341}, {10, 0.18066, 0.26589, -0.25479}, {20, 0.18133, 0.26846, -0.26876}, {30, 0.18208, 0.27119, -0.28539}, {40, 0.18293, 0.27407, -0.30470}, {50, 0.18388, 0.27709, -0.32675}, {60, 0.18494, 0.28021, -0.35156}, {70, 0.18611, 0.28342, -0.37915}, {80, 0.18740, 0.28668, -0.40955}, {90, 0.18880, 0.28997, -0.44278}, {100, 0.19032, 0.29326, -0.47888}, {125, 0.19462, 0.30141, -0.58204}, {150, 0.19962, 0.30921, -0.70471}, {175, 0.20525, 0.31647, -0.84901}, {200, 0.21142, 0.32312, -1.0182 }, {225, 0.21807, 0.32909, -1.2168 }, {250, 0.22511, 0.33439, -1.4512 }, {275, 0.23247, 0.33904, -1.7298 }, {300, 0.24010, 0.34308, -2.0637 }, {325, 0.24702, 0.34655, -2.4681 }, {350, 0.25591, 0.34951, -2.9641 }, {375, 0.26400, 0.35200, -3.5814 }, {400, 0.27218, 0.35407, -4.3633 }, {425, 0.28039, 0.35577, -5.3762 }, {450, 0.28863, 0.35714, -6.7262 }, {475, 0.29685, 0.35823, -8.5955 }, {500, 0.30505, 0.35907, -11.324 }, {525, 0.31320, 0.35968, -15.628 }, {550, 0.32129, 0.36011, -23.325 }, {575, 0.32931, 0.36038, -40.770 }, {600, 0.33724, 0.36051, -116.45 } }; #define NISO sizeof(isotempdata)/sizeof(ISOTEMPERATURE) // Robertson's method cmsBool CMSEXPORT cmsTempFromWhitePoint(cmsFloat64Number* TempK, const cmsCIExyY* WhitePoint) { cmsUInt32Number j; cmsFloat64Number us,vs; cmsFloat64Number uj,vj,tj,di,dj,mi,mj; cmsFloat64Number xs, ys; _cmsAssert(WhitePoint != NULL); _cmsAssert(TempK != NULL); di = mi = 0; xs = WhitePoint -> x; ys = WhitePoint -> y; // convert (x,y) to CIE 1960 (u,WhitePoint) us = (2*xs) / (-xs + 6*ys + 1.5); vs = (3*ys) / (-xs + 6*ys + 1.5); for (j=0; j < NISO; j++) { uj = isotempdata[j].ut; vj = isotempdata[j].vt; tj = isotempdata[j].tt; mj = isotempdata[j].mirek; dj = ((vs - vj) - tj * (us - uj)) / sqrt(1.0 + tj * tj); if ((j != 0) && (di/dj < 0.0)) { // Found a match *TempK = 1000000.0 / (mi + (di / (di - dj)) * (mj - mi)); return TRUE; } di = dj; mi = mj; } // Not found return FALSE; } // Compute chromatic adaptation matrix using Chad as cone matrix static cmsBool ComputeChromaticAdaptation(cmsMAT3* Conversion, const cmsCIEXYZ* SourceWhitePoint, const cmsCIEXYZ* DestWhitePoint, const cmsMAT3* Chad) { cmsMAT3 Chad_Inv; cmsVEC3 ConeSourceXYZ, ConeSourceRGB; cmsVEC3 ConeDestXYZ, ConeDestRGB; cmsMAT3 Cone, Tmp; Tmp = *Chad; if (!_cmsMAT3inverse(&Tmp, &Chad_Inv)) return FALSE; _cmsVEC3init(&ConeSourceXYZ, SourceWhitePoint -> X, SourceWhitePoint -> Y, SourceWhitePoint -> Z); _cmsVEC3init(&ConeDestXYZ, DestWhitePoint -> X, DestWhitePoint -> Y, DestWhitePoint -> Z); _cmsMAT3eval(&ConeSourceRGB, Chad, &ConeSourceXYZ); _cmsMAT3eval(&ConeDestRGB, Chad, &ConeDestXYZ); // Build matrix _cmsVEC3init(&Cone.v[0], ConeDestRGB.n[0]/ConeSourceRGB.n[0], 0.0, 0.0); _cmsVEC3init(&Cone.v[1], 0.0, ConeDestRGB.n[1]/ConeSourceRGB.n[1], 0.0); _cmsVEC3init(&Cone.v[2], 0.0, 0.0, ConeDestRGB.n[2]/ConeSourceRGB.n[2]); // Normalize _cmsMAT3per(&Tmp, &Cone, Chad); _cmsMAT3per(Conversion, &Chad_Inv, &Tmp); return TRUE; } // Returns the final chrmatic adaptation from illuminant FromIll to Illuminant ToIll // The cone matrix can be specified in ConeMatrix. If NULL, Bradford is assumed cmsBool _cmsAdaptationMatrix(cmsMAT3* r, const cmsMAT3* ConeMatrix, const cmsCIEXYZ* FromIll, const cmsCIEXYZ* ToIll) { cmsMAT3 LamRigg = {{ // Bradford matrix {{ 0.8951, 0.2664, -0.1614 }}, {{ -0.7502, 1.7135, 0.0367 }}, {{ 0.0389, -0.0685, 1.0296 }} }}; if (ConeMatrix == NULL) ConeMatrix = &LamRigg; return ComputeChromaticAdaptation(r, FromIll, ToIll, ConeMatrix); } // Same as anterior, but assuming D50 destination. White point is given in xyY static cmsBool _cmsAdaptMatrixToD50(cmsMAT3* r, const cmsCIExyY* SourceWhitePt) { cmsCIEXYZ Dn; cmsMAT3 Bradford; cmsMAT3 Tmp; cmsxyY2XYZ(&Dn, SourceWhitePt); if (!_cmsAdaptationMatrix(&Bradford, NULL, &Dn, cmsD50_XYZ())) return FALSE; Tmp = *r; _cmsMAT3per(r, &Bradford, &Tmp); return TRUE; } // Build a White point, primary chromas transfer matrix from RGB to CIE XYZ // This is just an approximation, I am not handling all the non-linear // aspects of the RGB to XYZ process, and assuming that the gamma correction // has transitive property in the transformation chain. // // the algorithm: // // - First I build the absolute conversion matrix using // primaries in XYZ. This matrix is next inverted // - Then I eval the source white point across this matrix // obtaining the coefficients of the transformation // - Then, I apply these coefficients to the original matrix // cmsBool _cmsBuildRGB2XYZtransferMatrix(cmsMAT3* r, const cmsCIExyY* WhitePt, const cmsCIExyYTRIPLE* Primrs) { cmsVEC3 WhitePoint, Coef; cmsMAT3 Result, Primaries; cmsFloat64Number xn, yn; cmsFloat64Number xr, yr; cmsFloat64Number xg, yg; cmsFloat64Number xb, yb; xn = WhitePt -> x; yn = WhitePt -> y; xr = Primrs -> Red.x; yr = Primrs -> Red.y; xg = Primrs -> Green.x; yg = Primrs -> Green.y; xb = Primrs -> Blue.x; yb = Primrs -> Blue.y; // Build Primaries matrix _cmsVEC3init(&Primaries.v[0], xr, xg, xb); _cmsVEC3init(&Primaries.v[1], yr, yg, yb); _cmsVEC3init(&Primaries.v[2], (1-xr-yr), (1-xg-yg), (1-xb-yb)); // Result = Primaries ^ (-1) inverse matrix if (!_cmsMAT3inverse(&Primaries, &Result)) return FALSE; _cmsVEC3init(&WhitePoint, xn/yn, 1.0, (1.0-xn-yn)/yn); // Across inverse primaries ... _cmsMAT3eval(&Coef, &Result, &WhitePoint); // Give us the Coefs, then I build transformation matrix _cmsVEC3init(&r -> v[0], Coef.n[VX]*xr, Coef.n[VY]*xg, Coef.n[VZ]*xb); _cmsVEC3init(&r -> v[1], Coef.n[VX]*yr, Coef.n[VY]*yg, Coef.n[VZ]*yb); _cmsVEC3init(&r -> v[2], Coef.n[VX]*(1.0-xr-yr), Coef.n[VY]*(1.0-xg-yg), Coef.n[VZ]*(1.0-xb-yb)); return _cmsAdaptMatrixToD50(r, WhitePt); } // Adapts a color to a given illuminant. Original color is expected to have // a SourceWhitePt white point. cmsBool CMSEXPORT cmsAdaptToIlluminant(cmsCIEXYZ* Result, const cmsCIEXYZ* SourceWhitePt, const cmsCIEXYZ* Illuminant, const cmsCIEXYZ* Value) { cmsMAT3 Bradford; cmsVEC3 In, Out; _cmsAssert(Result != NULL); _cmsAssert(SourceWhitePt != NULL); _cmsAssert(Illuminant != NULL); _cmsAssert(Value != NULL); if (!_cmsAdaptationMatrix(&Bradford, NULL, SourceWhitePt, Illuminant)) return FALSE; _cmsVEC3init(&In, Value -> X, Value -> Y, Value -> Z); _cmsMAT3eval(&Out, &Bradford, &In); Result -> X = Out.n[0]; Result -> Y = Out.n[1]; Result -> Z = Out.n[2]; return TRUE; }