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greg |
1.2 |
{ RCSid $Id$ } |
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greg |
1.1 |
{ |
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von Kries white point transformation |
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Input: |
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w0x, w0y - original white point chromaticity coords. |
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w1x, w1y - destination white point chromaticities |
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Output: |
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C00 to C22 - XYZ conversion matrix |
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} |
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MatDot(A,B,i,j) : A(i,0)*B(0,j) + A(i,1)*B(1,j) + A(i,2)*B(2,j); |
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i3(i) : if(i-2.5, i-3, i); |
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MinorDet(M,i,j) : M(i3(i+1),i3(j+1))*M(i3(i+2),i3(j+2)) - |
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M(i3(i+1),i3(j+2))*M(i3(i+2),i3(j+1)); |
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Det(M) : M(0,0)*MinorDet(M,0,0) + |
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M(0,1)*MinorDet(M,0,1) + |
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M(0,2)*MinorDet(M,0,2); |
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Inv(M,i,j) : MinorDet(M,j,i) / Det(M); |
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{ Original matrix from p. 480 of "Digital Color Management" } |
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{ |
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vKmat(i,j) : select(i*3+j+1, .40024, .70760, -.08081, |
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-.22630,1.16532,.04570, |
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0, 0, .91822 ); |
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} |
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{ Primary conversion matrix copied from Susstrunk's paper (CMCCAT2000) } |
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{ |
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vKmat(i,j) : select(i*3+j+1, .7982, .3389, -.1371, |
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-.5918, 1.5512, .0406, |
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.0008, .0239, .9753 ); |
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} |
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{ Sharp conversion matrix (also from Susstrunk paper) } |
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vKmat(i,j) : select(i*3+j+1, 1.2694, -.0988, -.1706, |
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-.8364, 1.8006, .0357, |
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.0297, -.0315, 1.0018 ); |
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ivKmat(i,j) : Inv(vKmat,i,j); |
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X0 = w0x/w0y; |
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Y0 = 1; |
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Z0 = (1-w0x-w0y)/w0y; |
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X1 = w1x/w1y; |
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Y1 = 1; |
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Z1 = (1-w1x-w1y)/w1y; |
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rho0 = vKmat(0,0)*X0 + vKmat(0,1)*Y0 + vKmat(0,2)*Z0; |
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gam0 = vKmat(1,0)*X0 + vKmat(1,1)*Y0 + vKmat(1,2)*Z0; |
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bet0 = vKmat(2,0)*X0 + vKmat(2,1)*Y0 + vKmat(2,2)*Z0; |
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rho1 = vKmat(0,0)*X1 + vKmat(0,1)*Y1 + vKmat(0,2)*Z1; |
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gam1 = vKmat(1,0)*X1 + vKmat(1,1)*Y1 + vKmat(1,2)*Z1; |
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bet1 = vKmat(2,0)*X1 + vKmat(2,1)*Y1 + vKmat(2,2)*Z1; |
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shiftMat(i,j) = select(i*3+j+1, rho1/rho0, 0, 0, |
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0, gam1/gam0, 0, |
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0, 0, bet1/bet0 ); |
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M1(i,j) = MatDot(ivKmat,shiftMat,i,j); |
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C(i,j) = MatDot(M1,vKmat,i,j); |
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{ Defined as constants so one evaluation only } |
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C00 : C(0,0); C01 : C(0,1); C02 : C(0,2); |
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C10 : C(1,0); C11 : C(1,1); C12 : C(1,2); |
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C20 : C(2,0); C21 : C(2,1); C22 : C(2,2); |
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{ Extra goodies... } |
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XYZ2VYU(j,i) : select(i*3+j+1, 1.362,0,.033,-1.093,1,-.631,-.205,0,.507); |
