System for printing color images with extra colorants in addition to primary colorants
First Claim
1. In a digital printing apparatus capable of printing a desired color as a combination of a subset of a set of colorants, the set of colorants comprising at least first and second colorants and an intermediate colorant disposed between the first and second colorants in color space, the intermediate colorant being chromatic and disposed at an edge of a color gamut which the apparatus is capable of printing, a method of converting color primary image signals operative of the first colorant and second colorant to hi-fi image signals operative of the first colorant, second colorant, and intermediate colorant, comprising the step of:
- performing a substitution of a combination of the primary image signals with an intermediate image signal representative of the intermediate colorant according to a non-linear function in reflectance coordinates.
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Accused Products
Abstract
In a "hi-fi" color printing system, wherein colorants of secondary colors beyond the regular CMYK primary colorants are available, the colorants of the secondary colors are substituted for combinations of the primary colorants in order to obtain a full color gamut. The functions by which colorants of the secondary colors are substituted for primary colorant are non-linear through a path in the color space.
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Citations
7 Claims
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1. In a digital printing apparatus capable of printing a desired color as a combination of a subset of a set of colorants, the set of colorants comprising at least first and second colorants and an intermediate colorant disposed between the first and second colorants in color space, the intermediate colorant being chromatic and disposed at an edge of a color gamut which the apparatus is capable of printing, a method of converting color primary image signals operative of the first colorant and second colorant to hi-fi image signals operative of the first colorant, second colorant, and intermediate colorant, comprising the step of:
performing a substitution of a combination of the primary image signals with an intermediate image signal representative of the intermediate colorant according to a non-linear function in reflectance coordinates. - View Dependent Claims (2, 3, 4, 5)
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6. In a digital printing apparatus capable of printing a desired color as a combination of a subject of a set of colorants, the set of colorants comprising at least first and second primary colorants and an intermediate colorant disposed between the first and second colorants in color space, the intermediate colorant being chromatic and disposed at an edge of a color gamut which the apparatus is capable of printing, a method of converting color primary image signals operative of the first colorant and second colorant to hi-fi signals operative of the first colorant, second colorant, and intermediate colorant, comprising the steps of:
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for obtaining colors in a first portion of color space between the first colorant and the second colorant, combining only the first colorant and the second colorant, a proportion of the first colorant to the second colorant varying in a linear function with varying distance in color space from the first colorant; and for obtaining colors in a second portion of color space between the first colorant and the second colorant, combining the second colorant with the intermediate colorant, a substitution of the second colorant and the intermediate colorant varying in a non-linear function with varying distance in color space from the second colorant. - View Dependent Claims (7)
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Specification