О сочетаниях цветов

Код на jscript для проверки сочетания цветов на ``читабельность'':

function color_brightness(red, green, blue) {
    return 0.299 * red + 0.587 * green + 0.114 * blue;
}

function color_is_good(bg_red, bg_green, bg_blue,
                       fg_red, fg_green, fg_blue) {
    var brightness_diff = Math.abs(
        color_brightness(bg_red, bg_green, bg_blue) -
        color_brightness(fg_red, fg_green, fg_blue));
    var color_dirr =
        Math.abs(bg_red - fg_red) +
        Math.abs(bg_green - fg_green) +
        Math.abs(bg_blue - fg_blue);
    return (brightness_diff > 0.490 && color_dirr > 1.961);
}