80 lines
4.2 KiB
C
80 lines
4.2 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "dsp/core/core.h"
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#include "dsp/core/illumination.h"
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#include "libc/str/str.h"
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const double kIlluminantA[3] = {1.0985, 1, 0.35585};
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const double kIlluminantAD10[3] = {1.11144, 1, 0.35200};
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const double kIlluminantC[3] = {0.98074, 1, 1.18232};
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const double kIlluminantCD10[3] = {0.97285, 1, 1.16145};
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const double kIlluminantD50[3] = {0.96422, 1, 0.82521};
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const double kIlluminantD50D10[3] = {0.9672, 1, 0.81427};
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const double kIlluminantD55[3] = {0.95682, 1, 0.92149};
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const double kIlluminantD55D10[3] = {0.95799, 1, 0.90926};
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const double kIlluminantD65[3] = {0.95047, 1, 1.08883};
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const double kIlluminantD65D10[3] = {0.94811, 1, 1.07304};
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const double kIlluminantD75[3] = {0.94972, 1, 1.22638};
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const double kIlluminantD75D10[3] = {0.94416, 1, 1.20641};
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const double kIlluminantF2[3] = {0.99187, 1, 0.67395};
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const double kIlluminantF2D10[3] = {1.0328, 1, 0.69026};
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const double kIlluminantF7[3] = {0.95044, 1, 1.08755};
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const double kIlluminantF7D10[3] = {0.95792, 1, 1.07687};
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const double kIlluminantF11[3] = {1.00966, 1, 0.6437};
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const double kIlluminantF11D10[3] = {1.03866, 1, 0.65627};
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/**
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* System of equations used for changing illumination.
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*
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* @see brucelindbloom.com/Eqn_ChromAdapt.html “The Bradford method is
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* the newest of the three methods, and is considered by most
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* experts to be the best of them. This is the method used in Adobe
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* Photoshop. A related article comparing the chromatic adaptation
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* algorithms may be found here.” ─Quoth Bruce Lindbloom
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*/
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const double kBradford[3][3] = {
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{0.8951, 0.2664, -.1614},
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{-.7502, 1.7135, 0.0367},
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{0.0389, -.0685, 1.0296},
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};
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/**
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* Computes lightbulb changing coefficients.
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*
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* @param R will store result
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* @param S has intended input illuminant primaries
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* @param D has desired output illuminant primaries
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* @return R
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* @see brucelindbloom.com/Eqn_ChromAdapt.html
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* @see fluxometer.com/rainbow/
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*/
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void *GetChromaticAdaptationMatrix(double R[3][3], const double S[3],
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const double D[3]) {
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double M[3][3], T[3][3], U[3][3], V[3], W[3];
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matvmul3(V, kBradford, S);
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matvmul3(W, kBradford, D);
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memset(M, 0, sizeof(M));
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M[0][0] = W[0] / V[0];
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M[1][1] = W[1] / V[1];
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M[2][2] = W[2] / V[2];
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return matmul3(R, matmul3(T, kBradford, M),
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inv3(U, kBradford, det3(kBradford)));
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}
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