Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1992-10-09
1996-02-06
Ip, Paul
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358455, 358283, H04N 140
Patent
active
054899915
ABSTRACT:
A computer-implemented method generates digital halftone matrices of selected size for use in an image processing system in which bi-level images are formed from continuous tone input images using the digital halftone matrices. In accordance with the method, a two-dimensional array of storage positions is defined for storing values. The two-dimensional array is divided into four quadrants of equal size, each quadrant having a quadrant origin, a quadrant perimeter and four subquadrants disposed around the quadrant origin. The storage positions of a first pair of diagonal quadrants are assigned threshold values arranged in order of increasing magnitude from the quadrant origin toward the quadrant perimeter completing concentric squares of threshold values as the magnitude increases. The storage positions of a second pair of diagonal quadrants are assigned threshold values arranged in order of increasing magnitude from the quadrant perimeter toward the quadrant origin completing concentric squares of threshold values as the magnitude increases. Each quadrant has threshold values arranged in alternating pairs diagonally opposing subquadrants to provide bi-lateral symmetry.
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International Business Machines - Corporation
Ip Paul
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