A method of applying a tone scale function that is compressive, expansive
or a combination of both to a digital image, the method including
decomposing the tone scale function into two or more composite functions
that can be applied sequentially to the digital image; applying the first
composite function to the digital image with a tone scale applicator to
produce a tone scaled digital image; and applying the second composite
function to the tone scaled digital image to produced an enhanced digital
image.