System for printing color images with extra colorants in addition to primary colorants
First Claim
Patent Images
1. In a printing apparatus capable of printing a desired color as a combination of a set of colorants, a method of selecting colorants for printing a desired color- comprising the steps of:
- defining combinations of colorants comprising at least a first colorant, second colorant, and third colorant as a main gamut, the main gamut substantially evenly surrounding an origin in device-independent color space;
defining an extended gamut as including colors printable with a fourth colorant combined with at least the first colorant but excluding the second colorant;
locating the desired color in a device-independent color space wherein the main gamut does not intersect with the extended gamut, thereby determining whether the desired color is in the main gamut or the extended gamut;
if the desired color is in the main gamut, printing the desired color with at least one colorant selected from a group of colorants including the first colorant and second colorant hut excluding the fourth colorant; and
if the desired color is in the extended gamut, printing the desired color with at least one colorant selected from a group of colorants including the first colorant and the fourth colorant hut excluding the second colorant.
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Abstract
In a "hi-fi" color printing system, wherein colorants of hi-fi colors beyond the regular CMYK primary colorants are available, a main gamut obtainable with the CMYK colorants only is mutually exclusive with at least one extended gamut in which a hi-fi colorant is used and a complementary one of the CMY colorants is excluded. Because the main and extended gamuts are mutually exclusive, no more than four colorants are used in any part of the image, and no more than four halftone screens need be used to obtain any desired color.
150 Citations
12 Claims
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1. In a printing apparatus capable of printing a desired color as a combination of a set of colorants, a method of selecting colorants for printing a desired color- comprising the steps of:
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defining combinations of colorants comprising at least a first colorant, second colorant, and third colorant as a main gamut, the main gamut substantially evenly surrounding an origin in device-independent color space; defining an extended gamut as including colors printable with a fourth colorant combined with at least the first colorant but excluding the second colorant; locating the desired color in a device-independent color space wherein the main gamut does not intersect with the extended gamut, thereby determining whether the desired color is in the main gamut or the extended gamut; if the desired color is in the main gamut, printing the desired color with at least one colorant selected from a group of colorants including the first colorant and second colorant hut excluding the fourth colorant; and if the desired color is in the extended gamut, printing the desired color with at least one colorant selected from a group of colorants including the first colorant and the fourth colorant hut excluding the second colorant. - View Dependent Claims (2, 3, 4, 5, 6)
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7. In a printing apparatus capable of printing a desired color as a combination of colorants, a method of selecting colorants for printing a desired color, comprising the steps of:
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defining combinations of CMY colorants as a main gamut; defining an extended gamut as including colors printable with a non-CMY hi-fi colorant combined with at least a first CMY colorant and excluding a second CMY colorant; locating the desired color in a device-independent color space wherein the main gamut does not intersect with the extended gamut, thereby determining whether the desired color is in the main gamut or the extended gamut; if the desired color is located in the main gamut, printing the desired color with at least one colorant selected only from the CMY colorants; and if the desired color is located in the extended gamut, printing the desired color with at least one colorant selected from a group of colorants comprising the hi-fi colorant and excluding the second CMY colorant. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification