Data processing system and method for producing shifted-element halftone screens

Abstract

A data processing system and method are described for generating a halftone screened image from an input image. A first threshold matrix is generated which, when utilized to halftone a solid gray input image, generates a first halftoned output image which is a plurality of generally solid vertical lines. The first threshold matrix includes a plurality of matrix elements arranged in a plurality of rows and a plurality of columns. A plurality of groups of the matrix elements are shifted within the first threshold matrix to create a second threshold matrix which, when utilized to halftone the solid gray input image, generates a second halftoned output image which is a checkerboard type pattern of alternating black or white blocks. In one embodiment, groups of the plurality of the rows are shifted horizontally over by at least one adjacent column to generate the second matrix.

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