Digital Halftoning

Along with text and graphics, images are fast becoming a generic data type forgeneral-purpose computer systems. This poses new problems for the systems designer, who must be ableto preprocess digital image data for a wide variety of video and hard copy displays. Digitalhalftoning, the method by which the illusion of continuous-tone images are created through thearrangement of binary picture elements, is a key component of any preprocessing.Digital Halftoningaddresses the problem of developing algorithms that best match the specific parameters of any targetdisplay device. It is the first significant study of the process of producing quality images onpractical computer displays.To aid the systems designer, Ulichney devises the concept of blue noise- which has many desirable properties for halftoning - and suggests efficient algorithms for itsuse. He also introduces new metrics for analyzing the frequency content of periodic and aperiodicpatterns for both rectangular and hexagonal grids, and presents a unique "aspect ratio immunity"argument in favor of hexagonal grids. Included are several carefully selected digitally-producedimages.Robert Ulichney is Principle Engineer with the Digital Equipment Corporation.

Robert Ulichney is Principle Engineer with the Digital Equipment Corporation.