Nonlinear operators for error diffusion

The error diffusion halftoning method preserves details well, but produces some unwanted regular texture patterns. The purpose of this paper is to introduce certain nonlinear operators with small kernels for the error diffusion to reduce the regular patterns. The goal is to suppress pattern artifacts while maintaining a small neighborhood. The method employed uses nonlinear diffusion operators, which possess a relatively complex distribution mechanism, thereby suppressing noticeable patterns. Two nonlinear filter classes are considered: polynomial and median type filters. We found that reduction of regular patterns without producing excessively grainy images is obtained using a combination of linear and median error feedback operators.