{
	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)));