A method of enhancing the tonal characteristics of a digital image, includes
receiving
a source digital image including a plurality of pixels; producing a tone scale
function that can be used to enhance the tonal characteristics of the source digital
image; classifying the tone scale function into one of two or more categories based
on the effect the tone scale function will have on the numerical range of pixel
values, wherein the classification categories include expansive and compressive;
and using the tone scale function, the source digital image, and a spatial filter
to produce an enhanced digital image when the tone scale function has been classified
as compressive, and using the tone scale function and the source digital image
without a spatial filter to produce the enhanced digital image when the tone scale
function has been classified as expansive.