w3c color recommendation algo

w3c color

function checkVisibility(color1, color2) {
    // http://www.w3.org/TR/AERT#color-contrast

    // Color brightness is determined by the following formula:
    // ((Red value X 299) + (Green value X 587) + (Blue value X 114)) / 1000

    // Note: This algorithm is taken from a formula for converting RGB values to
    // YIQ values. This brightness value gives a perceived brightness for a color.

    // Color difference is determined by the following formula:
    // (maximum (Red value 1, Red value 2) - minimum (Red value 1, Red value 2)) + (maximum (Green value 1, Green value 2) - minimum (Green value 1, Green value 2)) + (maximum (Blue value 1, Blue value 2) - minimum (Blue value 1, Blue value 2))

    // The range for color brightness difference is 125. The range for color difference is 500.

    var red_max = Math.max(color1.r, color2.r);
    var red_min = Math.min(color1.r, color2.r);

    var green_max = Math.max(color1.g, color2.g);
    var green_min = Math.min(color1.g, color2.g);

    var blue_max = Math.max(color1.b, color2.b);
    var blue_min = Math.min(color1.b, color2.b);

    var color_diff = (red_max - red_min) + (green_max - green_min) + (blue_max - blue_min);
    var brightness_diff = ((color1.r * 299) + (color1.g * 587) + (color1.b * 114)) / 1000;
    return [color_diff, brightness_diff];
}