RGBW Color Space Conversion Using Triangular Segmentation

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Solution Overview

Problem

Existing color conversion systems for multi-primary displays, such as RGBW, face challenges in accurately converting colors between different color spaces, particularly when the white primary is positioned at the white-point, leading to issues with gamut limitations and color representation.

Innovation Solution

The system divides the CIE chromaticity diagram into three triangles using RGBW primaries and calculates specific matrices to linearly interpolate white values, allowing for conversion between RGBW and CIE XYZ color spaces, with additional matrices for handling out-of-gamut colors by preserving hue through clamping and scaling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the white primary is positioned at the white-point in RGBW color space, then the color conversion accuracy is improved, but the gamut representation becomes limited

Engineering Contradiction:
Improvecolor conversion accuracyVSAvoidgamut representation
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The chromaticity diagram is divided into multiple triangular regions, each with its own conversion matrix. This segmentation allows the system to handle different color regions separately, improving accuracy within each triangle while collectively covering a broader gamut across all regions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different conversion matrices are applied to different triangular regions of the chromaticity diagram. Each matrix is optimized for its specific region, providing locally optimal color conversion accuracy while collectively addressing the broader gamut representation issue.

Inventive Principle:
Principle #3Local quality

2Device complexity

If standard color conversion matrices are used for RGBW, then the conversion process is simplified, but out-of-gamut colors cannot be correctly represented

Engineering Contradiction:
Improveconversion process complexityVSAvoidout-of-gamut color representation
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The color space is divided into multiple triangular regions, each with dedicated conversion matrices. This segmentation ensures that out-of-gamut colors in any region can be correctly represented by the appropriate matrix, maintaining reliability without requiring a single complex universal matrix.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The chromaticity diagram is pre-divided into triangular regions and corresponding matrices are pre-calculated and stored. When conversion is needed, the system simply selects the appropriate pre-computed matrix based on the color's location, maintaining simplicity while ensuring correct out-of-gamut handling.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If hue preservation is prioritized for out-of-gamut colors, then color accuracy is improved, but luminosity differences become more noticeable

Engineering Contradiction:
Improvehue accuracyVSAvoidluminosity differences
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The conversion matrices are specifically designed to preserve hue parameters for out-of-gamut colors by adjusting the transformation coefficients. This parameter optimization ensures accurate hue representation while the patent acknowledges and manages the resulting luminosity variations as a separate consideration.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS7728846B2Method and apparatus for converting from source color space to RGBW target color space
Publication Date: 2010.06.01 SAMSUNG DISPLAY CO LTD
  • US7728846B2 patent drawing
  • US7728846B2 patent drawing
  • US7728846B2 patent drawing

AI summary

Systems and methods are disclosed to effect conversion of a three color primary image data set to a multiple color primary set in which one of the primaries is white. One method converts a three-color image data set comprising C1, C2, and C3 colors into a four-color image data set comprising C1, C2, C3 and W colors.