/usr/share/radiance/cieluv.cal is in radiance-materials 4R1+20120125-1.1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | { RCSid $Id: cieluv.cal,v 1.2 2005/05/25 04:44:25 greg Exp $ }
{
Compute Luv color space and color differences from XYZ primaries.
5/4/98 G.W.Larson
}
Xw = 1; Yw = 1; Zw = 1; { default white }
sq(x) : x*x;
up(Xi,Yi,Zi) : 4*Xi/(Xi + 15*Yi + 3*Zi);
vp(Xi,Yi,Zi) : 9*Yi/(Xi + 15*Yi + 3*Zi);
Ls(Yi) : if(Yi/Yw - .01, 116*(Yi/Yw)^(1/3) - 16, 903.3*Yi/Yw);
us(Xi,Yi,Zi) : 13*Ls(Yi)*(up(Xi,Yi,Zi) - up(Xw,Yw,Zw));
vs(Xi,Yi,Zi) : 13*Ls(Yi)*(vp(Xi,Yi,Zi) - vp(Xw,Yw,Zw));
dE(X1,Y1,Z1,X2,Y2,Z2) : sqrt(sq(Ls(Y1)-Ls(Y2)) + sq(us(X1,Y1,Z1)-us(X2,Y2,Z2))
+ sq(vs(X1,Y1,Z1)-vs(X2,Y2,Z2)));
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