1. A method of enhancing the tonal characteristics of a digital image, comprising the steps of: a) receiving a source digital image including a plurality of pixels; b) producing a tone scale function that can be used to enhance the tonal characteristics of the source digital image; c) 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 d) 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.