Multilevel halftone screen and sets thereof

Abstract

A three-dimensional halftone screen is provided that is suited for multilevel printing. The three-dimensional halftone screen includes a plurality of planes each corresponding to one or more input intensity levels of an input RIPped pixel. Within the planes are screen dots, each associated with one or more output exposure intensity values representing an intensity of an exposure dot corresponding to the input RIPped pixel.

1 . A halftone screen represented by data and stored in a data storage system, the halftone screen being compatible with a multilevel halftoning process and comprising:
 a first plurality of screen dot nuclei, each of the first plurality of screen dot nuclei arranged a regular pattern corresponding to an AM screen in a mid-tone region; and   a second plurality screens having a stochastic arrangement of screen dot nuclei corresponding to an FM screen in regions outside of the mid-tone region;   wherein the dot nuclei in screens of the second plurality of screens associated with density levels that are proximate to the mid-tone region are arranged patterns that more closely approximate the regular pattern of the AM screen than the dot nuclei of screens that are not proximate to the mid-tone region.   
     
     
         2 . The halftone screen of  claim 1  wherein at lower boundary between the FM screens and the AM screens, the frequency of the screen dot nuclei are equal, and the transitional screen dot nuclei are in the same or substantially the same locations between planes at the transition point. 
     
     
         3 . The halftone screen of  claim 1  wherein at lower boundary between the FM screens and the AM screens, the frequency of the transitional screen dot nuclei advantageously also are equal, and the transitional screen dot nuclei are in the same or substantially the same locations between planes at the transition point.