Multibit screening of print documents in a pdl environment

Abstract

A high addressable multibit screening device and method for use in a PDL interpreter environment achieve improved printing resolution and quality. A PDL interpreter receives a PDL document from a host source, which identifies one or more objects that can be fully toned (black) or partially toned (line art or images). Each of these objects can be processed differently. Fully toned objects are processed within the interpreter and directly output in a predetermined output. Partially toned objects are sent to a high addressable screening module within the interpreter for processing prior to outputting in a desired output format. The high addressable screening module screens the partially toned objects to obtain multibit screened data for output. This can be achieved by converting an array of single threshold values to an array of three or more sub-threshold values in a way that preserves the pattern specified by the original threshold array (one bit per pixel image), but improves the quality of the rendered image relative to the quality of a one bit per pixel (per colorant) image. The partially toned data is then output with the fully toned objects for subsequent printing. This achieves an increase in available tints and spatial frequency for a given halftone pattern while reducing memory requirements.