1. A digital image processing method for processing a digital image having shadow portions and highlight portions, said method employing a tone reproduction function generated by normalizing a sample of tone values from the digital image, said tone reproduction function being applied to tone values of said digital image to produce processed tone values, characterized by the steps of: testing said sample of tone values for bimodal distribution; if the sample is bimodal, testing said sample of tone values to determine whether the image contains useful information in the shadow portions, and if useful information is contained in the shadow portions, adjusting the contrast of the image by increasing the contrast of the shadow portions of the image and decreasing the contrast of the highlight portions of the image.