Patent ID: 7755638

Claim:
An image processing method for transforming a selected portion of an initial color digital image received from a computer operable scanner into digital image objects with enhanced halftone edges for output in a computer print engine comprising: a) selecting a target color pixel location within the initial color digital image received from a computer operable scanner; b) observing a set of color pixels within a pixel observation window superimposed on the initial color digital image, relative to the target pixel location; c) generating, through use of a computer processor, edge-state codes for a plurality of pairs of neighboring vectors of pixels within the pixel observation window; d) generating, through use of the computer processor, using a computer architecture edge-identification codes from the plurality of edge-state codes using at least one look-up table wherein the edge-state codes are generated by i) generating a sum of weighted pixels values, for each of the vectors of pixels of the plurality of pairs of neighboring pixels that run through the pixel observation window using the computer processor; ii) calculating sum-to-sum differences for the neighboring pairs of vectors through use of the computer processor; and iii) encoding the edge-state codes for each pair of the neighboring vectors of pixels by using one or more bits to encode a magnitude and one bit to encode a sign of the sum-to-sum differences; and wherein the edge-identification codes indicate proximity to a tinted edge; and, e) transforming the edge-identification codes and the initial color digital image at the target color pixel into a halftone screen comprised of at least one of: a first halftone screen comprising a low fundamental frequency f and a first angle; and a second halftone screen comprising a high fundamental frequency √2×f and a second angle where the high fundamental frequency and the second angle have common frequency components which are harmonically matched to the first frequency and the first angle output through use of a computer operable print engine.