Color Conversion Table Creation Using Virtual Basic Color Axes
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Solution Overview
Problem
Conventional methods for creating color conversion tables in printers face challenges in fully utilizing the color gamut, especially in the vicinity of the color gamut's periphery, due to limitations in toner amount and the fixed ratio of CMY to K values, leading to reduced color reproducibility and gradation issues.
Innovation Solution
A color conversion table creation method that uses virtual basic color axes to correspond device values, allowing one virtual basic color axis value to increase while another decreases, and ensures black value monotonically increases with the minimum virtual basic color axis value, thereby expanding the color gamut and maintaining color continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a general profile chart such as ISO 12642 is used to create the color conversion table, then the colorimetric value can be used in or compared with other systems, but the device value cannot be uniquely settled because multiple CMYK combinations produce the same color value
Solution Approach 1:
The patent introduces virtual CMY coordinates as an intermediary between the measured color value and the device CMYK value. Instead of directly mapping color value to device value (which creates ambiguity), the virtual CMY coordinates serve as a mediator that enables unique determination of device values while maintaining compatibility with standard colorimetric systems.
2Manufacturing precision
If the device value is fixed in the chart to ensure unique determination, then the LUT can be created, but the range of color gamut that can be used in the printer is limited and cannot utilize the full color reproduction capability
Solution Approach 1:
The patent makes the virtual CMY coordinate system dynamic rather than fixed. By allowing the virtual CMY coordinates to be determined based on the actual printer's colorimetric characteristics, the system adapts to the printer's full color gamut capability. This dynamic approach enables the chart to utilize the entire color reproduction range of the printer while still ensuring unique device value determination.
3Stability of the object's composition
If the virtual CMY coordinate is used as an intermediate field with emphasis on continuity, then the device value correspondence is maintained, but the device value ratio of K and CMY cannot be optimized for color gamut expansion
Solution Approach 1:
The patent changes the parameters of the virtual CMY coordinate system to optimize color gamut utilization. Specifically, it determines the virtual CMY coordinates based on the printer's actual colorimetric characteristics, allowing the coordinate system parameters to be adjusted for maximum color gamut coverage while maintaining continuity. This enables optimal K and CMY value ratios to be achieved across the full color range.
Data Source
AI summary
Disclosed is a recording medium recording a program for a computer to perform the following functions of: creating first corresponding information to show color value corresponding to a combination of values of black and three basic colors when a plurality of color patches are each output; creating second corresponding information to correspond the combination of values of black and three basic colors to a virtual basic color axis coordinate; creating third corresponding information to show color value corresponding to the virtual basic color axis coordinate; and obtaining virtual basic color axis coordinate corresponding to the color value, obtaining a combination of values of black and three basic colors corresponding to the obtained virtual basic color axis coordinate, and storing the obtained combination of values of black and three basic colors as a combination of values of black and three basic colors corresponding to the color value.