A new method for digital multitoning using gray level separation

The problem of multitoning emerges as the result of advances on printing technology that allow the reproduction of different shades of gray applying techniques like multiple inks, different ink concentration or various dot sizes. The end result is an improvement in the quality of the reproduction. While some algorithms used for binary halftoning have been extended to deal with multitoning with a certain success, there is room for further improvement in the quality of the resulting images. Faheem, Arce, and Lau proposed gray level separation as a way to improve the quality of multitone images generated through error diffusion. In this paper a new gray level separation scheme is proposed whose objective is to ensure that black, gray and white pixels are printed in blue-noise patterns. The new scheme is applied to error diffusion as well as to the well known DBS algorithm. The results in both cases show an improvement in the texture of the printed patterns.