Go back to old luminescence values since the new ones produces to large values occasionally.

src/color/Color.js

@@ -78,11 +78,8 @@ var Color = this.Color = Base.extend(new function() {
 			// Using the standard NTSC conversion formula that is used for
 			// calculating the effective luminance of an RGB color:
 			// http://www.mathworks.com/support/solutions/en/data/1-1ASCU/index.html?solution=1-1ASCU
-			return new GrayColor(1 -
-					(color._red * 0.2989
-					+ color._green * 0.5866
-					+ color._blue * 0.1145),
-					color._alpha);
+			return new GrayColor(1 - (color._red * 0.2989 + color._green * 0.587
+					+ color._blue * 0.114), color._alpha);
 		},
 
 		'gray-rgb': function(color) {