Patent ID: 8068256

Claim:
A method for preparing to render a color image using a set of at least one hypocolorant in addition to other colorants, the method comprising: receiving color contone pixel information describing respective pixel portions of the color image; generating respective corresponding sets of contone colorant values for the respective pixel portions based on the received contone pixel information wherein the set of corresponding contone colorant values is generated in a manner that ensures that, for a selected pixel portion, when a non-zero value is generated in regard to the black colorant, a zero value is generated for each hypocolorant of the set of at least one hypocolorant, and that when a non-zero value is generated in regard to any hypocolorant of the set of at least one hypocolorant, a zero value is generated in regard to a black colorant; at least one of storing the generated respective sets of contone colorant values and providing the respective sets of contone colorant values for use in making marking decisions, selecting a first clustered shape halftone screen, the first clustered shape halftone screen being for use in making marking decisions regarding the black colorant, the first clustered shape screen being characterized, at least in part, by being based on a first set of fundamental halftone screen frequencies and a respective first set of halftone screen directions associated therewith; selecting a second clustered shape halftone screen, the second clustered shape halftone screen being for use in making marking decisions regarding the first hypocolorant of the set of at least one hypocolorant, the second clustered shape halftone screen being characterized, at least in part, by also being based on the first set of fundamental halftone screen frequencies and the respective first set of halftone screen directions associated therewith; halftoning colorant values from the respective sets of contone colorant values regarding the black colorant with the first clustered shape halftone screen, thereby making marking decisions regarding the black colorant; halftoning colorant values from the respective sets of contone colorant values regarding the first hypocolorant of the set of at least one hypocolorant with the second clustered shape halftone screen, thereby making marking decisions regarding the first hypocolorant; and at least one of storing the marking decisions regarding the black and first hypocolorant and marking a medium according to the marking decisions regarding the black and first hypocolorant.