Delta-Sigma Analysis of Image Halftoning by Error Diffusion

Prof. Brian L. Evans
Laboratory for Vision Systems
Dept. of Electrical and Computer Engineering
The University of Texas at Austin

research conducted in collaboration with
Mr. Thomas D. Kite (UT Austin), Prof. Alan C. Bovik (UT Austin), and
Dr. Terry Sculley (Crystal Semiconductor Corp.)

The error diffusion algorithm is an efficient way of converting grayscale images into high quality halftones. However, its operation is not well understood. We will show that error diffusion is a non-separable two-dimensional extension of delta-sigma modulation. Delta-sigma modulation analysis techniques explain features in halftones produced by classical error diffusion schemes, and allow the optimization of these schemes for high visual quality.


Brian L. Evans is an Assistant Professor in the Department of Electrical and Computer Engineering at The University of Texas at Austin, and the Associate Director of the Laboratory for Vision Systems within the Center for Vision and Image Sciences. His research interests include real-time software, embedded systems, heterogeneous systems, image and video processing systems, system-level design, symbolic computation, and computer-aided design. He has developed numerous computer-aided design tools to prototype and test research ideas. His B.S.E.E.C.S. (1987) degree is from the Rose-Hulman Institute of Technology, and his M.S.E.E. (1988) and Ph.D.E.E. (1993) degrees are from the Georgia Institute of Technology. From 1993 to 1996, he was a post-doctoral researcher at the University of California at Berkeley with the Ptolemy Project. Ptolemy is a research project and software environment focused on design methodology for signal processing, communications, and controls systems. He is the recipient of a 1997 NSF CAREER Award.