Dot diffusion is a halftoning technique that is based on the traditional error diffusion concept, but offers a high degree of
parallel processing by its block based approach. Traditional dot diffusion however suffers from periodicity artifacts. To
limit the visibility of these artifacts, we propose grid diffusion, which applies different class matrices for different blocks.
Furthermore, in this paper we will discuss two approaches in the dot diffusion framework to generate green-noise halftone
patterns. The first approach is based on output dependent feedback (hysteresis), analogous to the standard green-noise
error diffusion techniques. We observe that the resulting halftones are rather coarse and highly dependent on the used dot
diffusion class matrices. In the second approach we don't limit the diffusion to the nearest neighbors. This leads to less
coarse halftones, compared to the first approach. The drawback is that it can only cope with rather limited cluster sizes.
We can reduce these drawbacks by combining the two approaches.