1. A method of processing a digital image for production by an image forming device, the digital image comprising a plurality of elements, each element characterized by a range of pixel intensities represented in a first color depth, the method comprising: for each element in the digital image, determining if the magnitude of a pixel intensity gradient between an element of interest in a first window applied at each element and other elements in the first window satisfies a first predetermined condition; classifying those elements satisfying the first predetermined condition in a first category; creating a duplicate image by reducing the color depth of said digital image to a second color depth; applying a filter to elements of the duplicate image corresponding to those elements that are classified in the first category using a second window.