A multiscale error diffusion technique for digital halftoning

A new digital halftoning technique based on multiscale error diffusion is examined in this research. We use an image quadtree to represent the difference image between the input gray-level image and the output halftone image. An iterative algorithm is developed that searches the brightest region of a given image via “maximum intensity guidance” for assigning dots and diffuses the quantization error noncausally at each iteration. To measure the quality of halftone images, we adopt a new criterion based on hierarchical intensity distribution. The proposed method provides very good results both visually and in terms of the hierarchical intensity quality measure.