Improved digital multitoning with overmodulation scheme

over-modulation scheme Qing Yu and Kevin J. Parker Department of Electrical Engineering University of Rochester, Rochester, NY 14627 Kevin Spaulding and Rodney Miller Imaging Science Division Eastman Kodak Company, Rochester, NY 14650-1816 ABSTRACT Multilevel halftoning (multitoning) is an extension of bitonal halftoning, in which the appearance of intermediate tones is created by the spatial modulation of more than two tones, i.e., black, white, and one or more shades of gray. In this paper, a conventional multitoning approach and a speci c approach, both using stochastic screen dithering, are investigated. Typically, a human visual model is employed to measure the perceived halftone error for both algorithms. We compare the performance of each algorithm at gray levels near the intermediate printer output levels. Based on this study, an over-modulation algorithm is proposed. This algorithm requires little additional computation and the halftone output is mean-preserving with respect to the input. We will show that, with this simple over-modulation scheme, we will be able to manipulate the dot patterns around the intermediate output levels to achieve desired halftone patterns. Investigation on optimal output level selection and inkjet printing simulation for this new scheme will also be reported.