3D LUT Color Correction via Logarithmic Interpolation
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Solution Overview
Problem
Conventional 6-axis color correction algorithms used in 3D LUT circuits result in image quality deterioration, such as unnatural hue shifts and tone jumps, due to inconsistencies between the tone characteristics required by the algorithm and those provided by the 3D LUT circuit, leading to difficulties in achieving consistent color reproduction across different display products.
Innovation Solution
A color conversion data generation device and method that acquire end point correction values for the RGB color space, normalize intermediate colors using specific coefficients, interpolate these values with the same characteristic as the 3D LUT circuit, and inverse-normalize them to generate correction values, ensuring consistent color correction across different display products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a generic 3D LUT circuit is used for 6-axis adjustment, then the same color reproduction can be obtained between different display products, but image quality deteriorates due to inconsistency between the tone characteristic required by the 6-axis correction algorithm and the linear tone characteristic of the 3D LUT circuit
Solution Approach 1:
The patent changes the interpolation parameter from linear to logarithmic scale. The 3D LUT circuit performs logarithmic interpolation between correction points, matching the tone characteristic required by the 6-axis correction algorithm. This parameter change resolves the inconsistency between the algorithm's requirements and the circuit's characteristics, eliminating image quality deterioration while maintaining color reproduction consistency across different display products
Solution Approach 2:
The patent introduces dynamic adjustment of interpolation characteristics based on the input signal's luminance level. For intermediate luminance values, logarithmic interpolation is applied to match the 6-axis algorithm's tone characteristic. This dynamic approach allows the system to adapt its interpolation method to different signal conditions, ensuring both color consistency and image quality across the full luminance range
2Ease of operation
If conventional 6-axis correction algorithm is applied, then color correction can be performed, but image quality deterioration such as unnatural hue shift, tone jump, and color rolling occurs in gradations of intermediate colors
Solution Approach 1:
The patent changes the interpolation parameter from linear to logarithmic scale in the 3D LUT circuit. This parameter change transforms the interpolation characteristic to match the perceptual nature of human vision and the tone curve expectations of the 6-axis correction algorithm. As a result, intermediate color gradations are rendered naturally without hue shifts, tone jumps, or color rolling, while maintaining the ease of operation of the conventional 6-axis correction approach
Data Source
AI summary
A color conversion data generation device includes: an acquisition unit that acquires end point correction values for correcting a color of at least one end point of a RGB color space; an end point color correction value generation unit that corrects the color of the at least one end point using the acquired end point correction values, to generate end point color correction values; a normalization unit that normalizes an intermediate color in the RGB color space using a normalization coefficient; an interpolation unit that interpolates the normalized intermediate color using the generated end point color correction values by means of same interpolation characteristic as that of a 3D LUT circuit, to generate temporary correction values; and an inverse normalization unit that inverse-normalizes the generated temporary correction values using an inverse normalization coefficient defined according to the normalization coefficient, to generate correction values of the intermediate color.