{ RCSid $Id: uniq_rgb.cal,v 1.2 2019/06/10 13:56:52 greg Exp $ }
{
	Generate unique (distinguishable) RGB colors.

	8/28/2014	G. Ward

	Usage:
		cnt `rcalc -n -f xyz_srgb.cal -f cieluv.cal \
				-f uniq_rgb.cal -e '$1=Nu;$2=Nv'` \
			| rcalc -f xyz_srgb.cal -f cieluv.cal -f uniq_rgb.cal \
				-e '$1=Runq;$2=Gunq;$3=Bunq'
}
Umin : up(X(0,1,0),Y(0,1,0),Z(0,1,0));
Umax : up(X(1,0,0),Y(1,0,0),Z(1,0,0));
Vmin : vp(X(0,0,1),Y(0,0,1),Z(0,0,1));
Vmax : vp(X(0,1,0),Y(0,1,0),Z(0,1,0));

Yref : Y(0,0,1);

NDstep : 1/(13/7*Ls(Yref));

Nu : ceil((Umax - Umin)/NDstep);
Nv : ceil((Vmax - Vmin)/NDstep);

x_uv(u,v) : 9*u/(6*u - 16*v + 12);
y_uv(u,v) : 4*v/(6*u - 16*v + 12);

btwn(a,x,b) : if(x-a,b-x,-1);
and(a,b) : if(a, b, -1);

NeuMargin : 2*NDstep;

uneu : up(Yref,Yref,Yref);
vneu : vp(Yref,Yref,Yref);

utst = $1*NDstep + Umin;
vtst = $2*NDstep + Vmin;

Ytst : Yref;
Xtst = 9/4*utst/vtst * Ytst;
Ztst = (1/y_uv(utst,vtst) - 1)*Ytst - Xtst;

Rtst = R(Xtst,Ytst,Ztst);
Gtst = G(Xtst,Ytst,Ztst);
Btst = B(Xtst,Ytst,Ztst);

dist2neu = (utst-uneu)*(utst-uneu) + (vtst-vneu)*(vtst-vneu);

cond = and(btwn(0,Rtst,1), and(btwn(0,Gtst,1), and(btwn(0,Btst,1),
		dist2neu-NeuMargin*NeuMargin)));

sca = 1/max(Rtst,Gtst,Btst);
Runq = sca*Rtst;
Gunq = sca*Gtst;
Bunq = sca*Btst;