Color Conversion Table Creation for RGB to CMYK Mapping
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Solution Overview
Problem
Existing methods for color matching between devices with different color gamuts require extensive calculations, leading to lengthy processing times and irregularities in tone representation, resulting in suboptimal image quality when converting between RGB and CMYK color spaces.
Innovation Solution
A method that defines a color gamut for each device, determining correspondence relationships between surface and internal grid points in the RGB color space and parameters in the CMYK color space, creating a color conversion table that includes all grid points to facilitate efficient conversion without needing device-independent color spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If color conversion is performed through device-independent color space, then color matching between devices is achieved, but processing time increases and tone irregularities occur
Solution Approach 1:
The invention pre-calculates and stores correspondence relationships between grid points in device-dependent color spaces directly, without needing to convert through device-independent color spaces during actual color conversion operations. This preliminary preparation of conversion data eliminates runtime calculations and reduces processing time while maintaining color matching accuracy.
Solution Approach 2:
The invention extracts only the necessary correspondence relationships between color spaces by defining grid points within color gamuts and determining mappings only for these discrete points. This selective extraction avoids the computational overhead of full color space transformations while preserving essential color matching information.
2Reliability
If color conversion is performed through device-independent color space, then color matching is achieved, but tone irregularities are produced
Solution Approach 1:
The invention applies different treatment to different regions within the color gamut by defining grid points that are distributed throughout the three-dimensional color space. This localized approach ensures that correspondence relationships are established for specific color regions, maintaining tone accuracy locally while avoiding the smoothing effects that cause irregularities in global color space transformations.
Solution Approach 2:
The invention segments the continuous color space into discrete grid points that can be independently mapped between color spaces. By dividing the color gamut into manageable discrete points rather than treating it as a continuous transformation, the method preserves local tone characteristics and avoids the interpolation artifacts that cause tone irregularities in traditional color space conversions.
3Measurement precision
If comprehensive color conversion table is created, then conversion accuracy is improved, but processing load increases
Solution Approach 1:
The invention creates a comprehensive color conversion table by determining correspondence relationships for all grid points within the color gamut, including points on the surface and internal points. This partial coverage approach provides sufficient accuracy for most color conversions without requiring exhaustive mapping of every possible color value, thus balancing accuracy with processing efficiency.
Data Source
AI summary
A color-conversion-table creating method includes (a) defining a color gamut in a first color space defined for a first device, the color gamut having a surface, an internal space surrounded by the surface, surface grid points positioned on the surface, and internal grid points positioned in the internal space, and determining a correspondence relationship between the surface grid points in the first color space and parameters in a second color space defined for a second device, (b) determining, based on the correspondence relationship determined in step (a), a correspondence relationship between the internal grid points in the first color space and parameters in the second color space, and (c) creating a color conversion table indicative of a correspondence relationship between all grid points in the first color space and parameters in the second color space based on both the correspondence relationship determined in step (a) and the correspondence relationship determined in step (b).