Patent ID: 7054038

Claim:
A multi-color dithering method for the reproduction of color input images, the method being characterized by the use of a two-dimensional dither function, the use of an arbitrary number of primary colors and the use of partitions representing relative amounts of primary colors, the method comprising the steps of: (a) defining a two dimensional dither function G(x,y); (b) choosing a set of primary colors {C i } located within a three-dimensional color working space ABC; (c) initiating a neighbor finding procedure which renders neighboring primary colors {C j } of a given input color C in the three-dimensional color space ABC; (d) computing the primary color of each output image pixel O(x,y) by a set of substeps comprising: (i) locating in the input color image an input color location (x′,y′) associated to the output image pixel O(x,y) and computing its corresponding color C(x′,y′); (ii) finding N neighbor primary colors {C j } of C in the ABC color space by using the neighbor finding procedure; (iii) computing the amount S j (x,y) of every neighbor primary color C1; (iv) determining the output primary color O(x,y) at output pixel (x,y) by locating at each position (x,y) a partition P j (x,y) within which the dither function G(x,y) is situated, where upper and lower boundaries of partitions P 1 , P 2 , . . . PN are respectively defined by lower boundary 0 and upper boundary S 1 (x,y), lower boundary S 1 (x,y) and upper boundary S 1 (x,y)+S 2 (x,y), . . . , lower boundary S 1 (x,y)+S 2 (x,y)+ . . . +S N-1 (x,y) and upper boundary S 1 (x,y)+S 2 (x,y)+ . . . +S N (x,y), and by assigning to the output primary color O(x,y) the neighbor primary color C j associated to partition P j (x,y); and (e) outputting the multi-color dithered output image on an output device.