Multi-dot dither matrix generation

Abstract

An improved multi-dot halftoning method to print a non-text halftone image from a non-text gray-scale image by comparing the gray-scale image to a transformed dither matrix to generate and to print the halftone image. The transformed dither matrix is tuned to reduce undesirable artifacts in the printed image. In one set of process steps to generate the transformed dither matrix, an original dither matrix with a number of original levels is picked. A selected number of the original matrix is tiled to build the large dither matrix. The large dither matrix is then transformed by operating on every original level in the large dither matrix. Each original level is split to create a group of finer levels that are in sequence and are all different from each other. A processor then replaces that original level in each of the tiled matrices by one of the finer levels such that the sequence of finer levels follows a pattern in the large dither matrix. This step of replacement is repeated for all the possible patterns; and the pattern that creates the most visually-pleasing image is selected for that original level. After the step of selecting all the patterns comes the step of incorporating all the selected patterns into the large dither matrix to form the transformed dither matrix for printing the non-text image.

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