US 2009/0268218 A1 · HYPOCHROMATIC IMAGING

Abstract

Color management constraints on the use of selected hypocolorant(s) and a black colorant in the rendering of a given pixel reduce ink or toner usage and/or reduce pressure on an ink limit. Additionally, the enforcement of this mutual exclusivity between the black and the selected hypocolorant(s) allows screen frequencies and angles to be shared between halftone screens used for the black colorant and a selected hypocolorant. This reduces the likelihood of objectionable moiré associated with the use of hypocolorant colorants in addition to the conventional CMY(K) colorants. In some embodiments, color management constraints prevent the use of black colorant for pixels beyond a threshold lightness or luminance. This constraint allows the use of the selected hypocolorants in the region of color space beyond the threshold. The threshold can be a function of hue and/or chroma. In some embodiments the threshold is a constant.

Claims20

Dependent claims

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, and
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.

A system that is operative to prepare to render a color image using a set of at least one hypocolorant in addition to other colorants, the system comprising:

a contone value generator that is operative to receive color contone pixel information describing respective pixel portions of the color image and is operative to generate respective corresponding sets of contone colorant values for the respective pixel portions based on the received contone pixel information wherein the sets of corresponding contone colorant values are 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;
and,
at least one of a communications mechanism that provides the generated respective sets of contone colorant values for further processing and a storage device that receives the respective sets of contone colorant values and stores the generated respective sets of contone colorant values at least temporarily.

A system that is operative to prepare to render a color image using a set of at least one hypocolorant in addition to other colorants, the system comprising:

a contone value generator that is operative to receive color contone pixel information describing respective pixel portions of the color image and is operative to generate respective corresponding sets of contone colorant values for the respective pixel portions based on the received contone pixel information wherein the sets of corresponding contone colorant values are 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 at least a first selected hypocolorant of the set of at least one hypocolorant, and that when a non-zero value is generated in regard to at least the first selected hypocolorant of the set of at least one hypocolorant, a zero value is generated in regard to a black colorant;
a halftone screen assignment mechanism that is operative to select a first clustered shape halftone screen 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 and is operative to selecting a second clustered shape halftone screen for use in making marking decisions regarding at least the first selected 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;
a halftoner that is operative to halftone colorant values, from the respective sets of contone colorant values received from the storage device or communication mechanism, regarding the black colorant with the first clustered shape halftone screen, thereby making marking decisions regarding the black colorant and is operative to halftone colorant values from the respective sets of contone colorant values regarding at least the first selected hypocolorant of the set of at least one hypocolorant with the second clustered shape halftone screen, thereby making marking decisions regarding at least the first selected hypocolorant;
and
at least one of a storage device or portion that is operative to store the marking decisions regarding the black and at least the first selected hypocolorant and a rendering device that operates to mark a medium according to the marking decisions regarding the black and at least the first selected hypocolorant.

2 more elements

Dependencies are inferred from the claim text.

Hypochromatic imaging

Life of this patent

Hypochromatic imaging

Life of this patent

Abstract

Claims20