don@allegra.UUCP (Don Mitchell) (02/10/86)
Another useful paper on halftoning (simulating gray scale on bilevel displays) is Stoffel, J.C, "A Survey of Electronic Techniques for Pictorial Image Reproduction". IEEE Trans. Comm., Vol COM-29, No 12, December 1981. This paper discusses electronic screening techniques (unlike Jarvis) which I believe is a much better for printers. It produces images much like you find in newspapers. Ordered dither and Floyd-Steinberg tend to generate very high frequencies which make a mess when you try to print or xerox them. Electronic screening is done like ordered dither, but with a very different threshold matrix. For example: 10 12 11 9 7 8 13 18 17 6 1 2 14 15 16 5 4 3 9 7 8 10 12 11 6 1 2 13 18 17 5 4 3 14 15 16