1. A method for enhancing the contrast of an image that is represented by a digital signal, the method comprising: a computer decomposing said digital signal into a multi-scale representation comprising at least two detail images representing detail at multiple scales and approximation images from which the detail images are derived, an approximation image at a scale representing the grey values of said image in which all details at that scale have been omitted, the computer computing translation difference images of at least one approximation image, the computer non-linearly modifying the values of said translation difference images, the computer computing an amplification image at least one scale as the ratio of two images wherein the first image is computed by combining said modified translation difference images at the same or smaller scale and the second image is created by combining unenhanced translation difference images at the same or smaller scale, the computer computing an enhanced multi-scale detail representation by modifying at least one scale the detail image according to the amplification image at that scale, and the computer computing an enhanced image representation by applying a reconstruction algorithm to the enhanced multi-scale detail representation.