Modified Jointly-Blue Noise Mask Approach Using S-CIELAB Color Difference

©2002, IS&T—The Society for Imaging Science and Technology be difficult to apply conventional color halftoning techniques to high-fidelity color printing. In a blue noise halftoning method, the problems related to Moiré patterns in conventional screen designs are replaced by color image quality issues related to the overlay of blue noise patterns. A number of different schemes have been proposed for generating one or more blue noise masks for color halftoning. These schemes include the Dot-On-Dot scheme, Shifted Mask scheme, Inverted Mask scheme, and Four-Mask scheme.5 However, none of these schemes involves an analysis of the properties of the overlaid blue noise binary patterns and the interaction between the color channels is only partially considered. In the current study, to reduce the chrominance error, the low-pass filtered error and S-CIELAB chrominance error are both considered during the mask generation procedure and calculated for single and combined patterns. Using the calculated low-pass filtered error, the patterns are then updated by either adding or removing dots from the multiple binary patterns. Finally, the pattern that shows the lower S-CIELAB chrominance error is selected. The whole procedure is as follows: Three initial patterns are created from the input binary pattern power spectrum matching algorithm (BIPPSMA) mask. To make the gray level of a pattern one level down, randomly selected white dots are changed into black dots for each pattern. Thereafter, four combined patterns are created from the three single patterns, three double patterns are created by combining two single patterns, and one triple Introduction