Katrien Daels


Error diffusion (ED) is widely used in digital imaging as a binarization process which preserves fine detail and results in pleasant images. The process resembles the human visual system in that it exhibits an intrinsic edge enhancement An additional extrinsic edge enhancement can be controlled by varying the threshold. None of these characteristics has yet been fully explained due to the lack of a suitable mathematical model of the algorithm. The extrinsic sharpening introduced in 1-D error diffusion is the subject of this thesis. An available pulse density modulation(PDM) model generated from a frequency modulation is used to gain a better understanding of variables in ED. As a result, threshold variation fits the model as an additional phase modulation. Equivalent images are obtained by applying ED with threshold modulation or by preprocessing an image with an appropriate convolution mask and subsequently running standard ED.

Library of Congress Subject Headings

Image processing--Digital techniques; Imaging systems--Image quality; Threshold logic

Publication Date


Document Type


Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)


Eschbach, Reiner


Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works. Physical copy available through RIT's The Wallace Library at: TA1632 .D335 1991


RIT – Main Campus