A method of enhancing the tonal and chrominance characteristics of a
digital image, includes receiving a source digital image including
wherein the source digital image is in a luminance-chrominance
representation having a luminance digital image channel and at least two
chrominance digital image channels; 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 of a processed digital image wherein the
classification categories include expansive and compressive; using the
tone scale function and the luminance digital image channel to produce an
enhanced luminance digital image channel; and amplifying the chrominance
digital image channels to produce modified chrominance digital channels
when the tone scale function has been classified as expansive.