Many color display/printing systems provide several dithering options -- typically, none, ordered and "error diffusion". In ordered dithering, a repeated pattern of colors and background is used to produce a specific shade and intensity. This is not always satisfactory as it can produce patterned artifacts. In error diffusion, the same overall amounts of color and background are present as in ordered dithering, but their arrangement is randomized. Error Diffusion is generally thought usually to yield somewhat more satisfactory results than ordered dithering.
There are a wide variety of dithering algorithms in use besides Error Diffusion and ordered. Which is "best" is likely to depend on the specific image being presented, the capabilities of the medium, and on subjective factors. One possibility is that dithering that looks good on a computer monitor may not be satisfactory on a specific printer and vice versa.
Return To Index Copyright 1994-2002 by Donald Kenney.