--- ray/src/rt/rayinit.cal	1992/03/03 13:58:11	2.3
+++ ray/src/rt/rayinit.cal	1992/08/17 16:01:24	2.4
@@ -96,7 +96,7 @@ noneg(v) = if(v,v,0);
 red(r,g,b) = if(r,r,0);
 green(r,g,b) = if(g,g,0);
 blue(r,g,b) = if(b,b,0);
-grey(r,g,b) = .3*r + .59*g + .11*b;
+grey(r,g,b) = noneg(.263*r + .655*g + .082*b);
 clip_r(r,g,b) = bound(0,r,1);
 clip_g(r,g,b) = bound(0,g,1);
 clip_b(r,g,b) = bound(0,b,1);