Abstract: A technique for reducing image artifacts is described. The technique includes utilizing a clustered-dot dither matrix having a plurality of layers with each of the layers arranged in one of a plurality of complementary patterns within the dither matrix. By using a dither matrix which generates layers of dots in complementary patterns, image banding artifacts and ink bleeding characteristics resulting from a printer generating a halftone image using a clustered-dot dithering technique are reduced.

Abstract: A multi-stage, preprocessing technique increases the quality of a monochrome or colored mixed-mode document printed on a binary-type printer. The document is preferably apportioned into a plurality of small tiles, each of which provides information to the inventive technique for eventually defining the modes as either text or images. The multi-stage technique comprises a first stage for normalizing a non-ideal histogram of the mixed-mode document to a histogram having an ideal distribution of selected pixel values. A second stage classifies each tile as either text, image or background, while a third stage collates groups of tiles in both vertical and horizontal directions to remove variances in the document. Those portions of the document classified as images are then halftone processed, while the text areas are threshold processed to thereby significantly improve the reproduction quality of the printed document.

Abstract: An ink-jet-printer driver employs clustered-dot dither to generate binary image signals that represent an image that has been adjusted for the ink-duty limit that must be imposed to avoid bleeding on some print media. To impose the limit, a Bayer dither process (94) receives an input that represents the ratio of ink-limit-adjusted ink duty to unadjusted ink duty. A gating operation (96) permits an ink request only at those locations where both dither processes (92 and 94) indicate that an ink is permitted.