Some color functions

color.js

/**
 * Given an integer representing the hexadecimal
 * value for a color, returns an array containing
 * the RGB values from 0 to 255
 * @param val the integer representing the color
 * @returns   the array of RGB values
 */
function toRGB(val) {
	var r = (val & 0xFF0000) >>> 16;
	var g = (val & 0x00FF00) >>> 8;
	var b = val & 0x0000FF;
	return [r, g, b];
}

/**
 * Given an array of RGB values from 0 to 255
 * this will return the integer value that
 * represents the color
 * @param rgb the array of RGB values
 * @returns   the integer representing the color
 */
function fromRGB(rgb) {
	return rgb[0] << 16 | rgb[1] << 8 | rgb[2];
}

/**
 * Gets the luma value based upon ITU-R Rec 709
 * coefficients.
 * @param val the integer color value
 * @returns   the luma value
 */
function getPhotometricLuma(val) {
	var rgb = fromRGB(val);
	return 0.2126 * rgb[0] + 0.7152 * rgb[1] + 0.0722 * rgb[2];
}