Multilevel Halftoning Using Bilevel Quantizers

The introduction of digital printing devices, capable of printing multiple shades of gray, has triggered research focusing on multilevel halftoning algorithms. A major problem associated with conventional multilevel halftoning is the introduction of unwanted texture near the intermediate gray levels, in the printed image. In this paper, a novel halftoning algorithm, based on gray level separation, has been introduced and tested on gray scale ramps, using trilevel halftoning. With this method, we can control the proportion of gray and black pixels to represent a particular shade of gray. For certain combinations of the gray and black distribution curves, elimination of the undesirable banding artifacts near the intermediate gray level, in the output, has been achieved.