yiqBrightnessDiff method
Calculate difference in brightness of two colors. Helper method for goog.color.highContrast() @param {goog.color.Rgb} rgb1 Colour represented by a rgb array. @param {goog.color.Rgb} rgb2 Colour represented by a rgb array. @return {number} Brightness difference. @private
Implementation
int yiqBrightnessDiff(RgbColour rgb1)
{
return (rgb1.yiqBrightness() - yiqBrightness()).abs();
}