Abstract

Digital halftoning is the process of converting a continuous tone image or photograph into an array of printed and not printed dots such that, when viewed by the human visual system, the pattern creates an illusion of being a continuous shade of gray. Methods of halftoning that produce a periodic pattern of clustered dots that vary in size with tone are generally referred to as amplitude modulated (AM) halftoning while those that produce a random arrangement of isolated dots that vary in their spacing apart with tone are referred to as frequency modulated (FM) halftoning. Depending on the ability of a given printing process to produce isolated dots consistently, some dot distributions are better than others and choosing the optimal distribution of dots goes a long way in maximizing a given devices over all print quality. For this reason, digital halftoning has received significant interest from industry and academic researchers interested in digital image processing and the visual display of information. This website represents my effort to offer, to the non-specialist, a clear and concise description of the problem as well as an introductory review to the many approaches that have been proposed.