+ double r_diff = this.getColor().getRed() - eye.getColor().getRed();
+ double g_diff = this.getColor().getGreen() - eye.getColor().getGreen();
+ double b_diff = this.getColor().getBlue() - eye.getColor().getBlue();
+ // See https://en.wikipedia.org/wiki/Color_difference
+ Double distance = Math.sqrt(2 * Math.pow(r_diff, 2) + 4 * Math.pow(g_diff, 2) + 3 * Math.pow(b_diff, 2));
+ return distance.intValue();