Xerox Corporation

Yongda Chen

Yonghui Zhao

R Victor Klassen

Guo-Yau Lin

James Michael Sanchez

J Michael Sanchez

Michael Sanchez

Guo Yau Lin

A gamut mapping method and system for implementing out-of-gamut spot color reproduction, including a memory for electronically storing information related to at least one color gamut and a gamut mapping editor including a processor communicating with the memory, the processor of the gamut mapping editor (i) causing a user to be apprised that a target spot color is outside the at least one color gamut and (ii) facilitating the user's employment of one or more of a plurality of gamut mapping methodologies to select a preferred color from a plurality of mapped colors when the target spot color is outside the at least one color gamut.

Method and system for out-of-gamut spot color reproduction

Color separation systems and methods improve color constancy and smoothness of a color lookup table (LUT) for a printer. A plurality of nodes of the LUT may be defined in colorimetric space, and the nodes out of the printer gamut may be mapped to the printer gamut surface. All possible colorant combinations are then determined that produce each node in the LUT in a device independent color space based on an inversion of the spectral based printer model. Next, a specific image quality metric combination based on a color inconstancy index (CII) and a gray component replacement (CGR) strategy is defined. And a colorant combination is determined for each and every node in the LUT based on this metric. A smoothing filter may be used to smooth the lookup table.

Systems and methods for building a color lookup table for a printer

A spot color rendering system and method that incorporates spot color press emulation color transformation to preserve spot color on a target rendering device. A spot color rendering option implemented in a graphical user interface can be selected in order to render the spot color via an intermediate emulation space. The spot color name calls can be first associated with a color value in an ICC profile connection space (PCS), as CIE L*a*b* or XYZ. A database relation of the spot color name with its associated PCS numerical value enables association of the name with the resultant color transformed output. Thereafter, a color transformation with respect to the spot color value can be performed in order to compute a color on an emulation press and then the color can be preserved to the target rendering device. Such an approach enables a color consistent rendering to the target rendering device similar to that of the emulation press.

Spot color press emulation color transformation method and system

Color separation systems and methods improve color constancy and smoothness of a color lookup table (LUT) for a printer. A plurality of nodes of the LUT may be defined in colorimetric space, and the nodes out of the printer gamut may be mapped to the printer gamut surface. A set of possible colorant combinations are then determined that produce each node in the LUT in a device independent color space using a non-linear minimization algorithm, such as, for example, a conjugate gradient algorithm. Next, a colorant combination may be determined for each and every node in the LUT based on an image quality metric. In some implementations, a smoothing filter may be used to smooth the lookup table.

Mapping an input color space into a colorimetric subspace can generate a target colorimetry space. Initial device color values can be used to generate an initial reference colorimetry space. A penalty error between the target colorimetry space and the reference colorimetry space can be minimized by generating a next reference colorimetry space based on subsequent device colors.

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Pittsford, NY, United States of America

Yongda Chen