/**
 * Calculate HSL from RGB
 * Hue is in degrees [0..360]
 * Lightness: [0..1]
 * Saturation: [0..1]
 * http://web.archive.org/web/20060914040436/http://local.wasp.uwa.edu.au/~pbourke/colour/hsl/
 */
export declare function rgb2hsl(r: number, g: number, b: number): {
    h: number;
    s: number;
    l: number;
};