sierra@das.llnl.gov (Frankie Sierra) (03/06/90)
This message is to report an error-diffusion filter which is more simple to compute than Floyd-Steinberg, but produce the same per- formance as this standard filter. There have been many people confused about a filter attributed to Floyd and Steinberg, but whose origins are really unknown. To sim- plify this discussion I will refer to this filter as the False-Floyd- Steinberg (FalseFS). The FalseFS filter is described as: * 3 3 2 (over 8) This filter tends to lock in several patterns and artifacts for a wide range of luminance spectrum bands. The Floyd and Steinberg filter is more smoother in its transitions. The real Floyd and Steinberg filter (F&S) was introduced in a paper by its authors (Floyd, R. W. and L. Steinberg, "An Adaptive Algorithm for Spatial Gray Scale.", SID International Symposium Digest of Technical Papers, vol 1975m, pp. 36-37). The Floyd and Steinberg filter is known as: * 7 3 5 1 (over 16) I have been playing for more than a year on error diffusion filter design. And had already synthesized a bunch of filters with per- formance close to the Jarvis, Judice and Ninke (1976) filter but with less computational effort (If there is interest I could post a summary of these filters). Just recently, in my quest for re- ducing the filter to a minimum, I found out a filter with per- formance similar to the Floyd and Steinberg filter, but less computationally complex. This filter, which I enjoy calling the Sierra-Lite, is: * 2 1 1 (over 4) This is the one I currently use when I want speed. However, I rather use my other filters, when quality is of greater importance (the difference being 25% to 40% more time for a 640 X 480 X 8-bits images). Frankie Sierra sierra@das.llnl.gov 76356.2254@compuserve.com