Patent Document ID: 8995021
Application ID: 13916059
Patent Status: 1

Claim One:
1. A method of performing black trapping on a color image data representation, the color image representation including a black pixel bitmap and one or more non-black halftone pixel bitmaps for rendering comprising: a) determining if a black pixel of interest location associated with the black pixel bitmap is a pixel location associated with a natural extension of a halftone pattern associated with a non-black halftone pixel bitmap; b) estimating a continuous tone value associated with one or more black pixels within a predetermined window of pixels associated with the black pixel of interest location; c) determining if the black pixel of interest location is associated with an edge based on the continuous tone values associated with the one or more black pixels estimated in step b); d) determining an on/off state of black pixels within a 5×5 pixel area centered on the black pixel of interest; e) evaluating a plurality of logical expressions associated with the determined on/off state of black pixels within the 5×5 pixel area centered on the black pixel of interest, each logical expression including one or more logical operations applied to the determined on/off state of two or more of the black pixels within the 5×5 pixel area centered on the black pixel of interest, wherein the logical expressions provide a determination of a plurality of black bitmap pixel depth conditions within the 5×5 pixel area, each depth condition including a first black bitmap pixel bordering the black pixel of interest and a second black bitmap pixel bordering the first black bitmap pixel; and f) if the black pixel of interest is a natural extension of a halftone pattern associated with the halftone pixel bitmap, the black pixel of interest is associated with an edge, and one or more of the plurality of logical expressions is satisfied, modifying the non-black halftone pixel bitmap at the black pixel of interest location to turn the respective pixel on, thereby providing a natural extension of the halftone pattern associated with the non-black halftone pixel bitmap.