Abstract
New variable cluster-size FM halftoning algorithm VACS (VAriable Cluster Screen) has been developed. This method could apply individual binarization processing after dividing input image data into 3 areas, shadow, intermediate and highlight. At intermediate area, Output-dependent Feedback Error Diffusion (Green-Noise Method) is applied as binarization algorithm, which enables to vary clustered-dot size in accordance with gain parameter. At highlight and shadow areas, homogeneous clustered-dots are created by deciding cell size, searching neighboring pixels already binarized. Each area is continuously and homogeneously connected introducing variable threshold T, which varies in proportion to the input image data, and also is adjusted cluster size at the boundary selecting suitable thresholds Ts and Th. As the result, homogeneous clustered-dots are obtained for all gradation levels. Tunable capability adjusting printing engine characteristics and high quality document image processing are feasible as VACS applications.
