Patent ID: 7978371

Claim:
A method for vector halftoning in dot-on-dot printing devices, the method comprising: a non-transitory computer readable medium for storing instructions that, when executed on a computer, cause the computer to perform the method comprising: receiving an input C i /M i /Y i channels and a colorant K i ; in response to any of said input C i /M i /Y i channels being greater than a predetermined threshold, clipping each of said input C i /M i /Y i to 100−K i ; determining a minimum extra black coverage K′ based upon said input C i /M i /Y i channels and K i , where K′=max(sum i −200+2*K i ,0), and where sum i =C i +M i +Y i ; determining a minimum total coverage area of a secondary color RGB dot (rgb area) required to achieve a remaining CMY coverage; and in response to said minimum total coverage area being non-zero: removing said determined amount of minimum extra black coverage K′ to obtain an amount of remaining ink coverage given by: C 1 =C i −K′, M 1 =M i −K′, and Y 1 =Y i −K′, respectively; determining each of a primary output C o /M o /Y o ; for each of a C 2 /M 2 /Y 2 , determining a remaining primary color area (cmy_area) and a total remaining toner coverage (sum 2 ); scaling each of said determined primary outputs C o /M o /Y o by a ratio of said remaining primary color area over said total remaining toner coverage; adjusting a remaining C 3 /M 3 /Y 3 dedicated to formation of a secondary color to achieve a desired input CMY coverage; sorting said remaining C 3 /M 3 /Y 3 to produce sorted results; and determining secondary R o G o B o based on said sorted results.