3D LUT Color Conversion Segmentation
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Solution Overview
Problem
Existing color conversion methods using 3D LUTs face accuracy degradation due to interpolation, particularly failing to reproduce small gradation changes between lattice points, leading to reduced color reproducibility and accuracy.
Innovation Solution
A method that calculates and applies an expansion/contraction coefficient to correct gradation values, dividing input and output gradations into segments with predetermined intervals, allowing for accurate representation of gradation changes between lattice points, thereby reducing interpolation errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of lattice points in 3D LUT is increased to improve color reproducibility, then color accuracy is improved, but computational load and processing time increase significantly
Solution Approach 1:
The patent divides the 3D LUT into multiple sub-LUTs based on gray scale value ranges. Each sub-LUT handles a specific segment of the gray scale range, allowing for localized optimization. This segmentation enables the system to maintain high color accuracy in critical regions while reducing the overall computational burden by processing smaller, manageable segments rather than a single large LUT.
Solution Approach 2:
The patent applies different processing strategies to different regions of the gray scale range. Specifically, it uses correction tables for certain gray scale ranges and direct mapping for others, optimizing the approach based on the local requirements of each region. This local quality principle allows the system to maintain high precision where needed while reducing computational load in less critical areas.
2Productivity
If the number of lattice points in 3D LUT is thinned out to reduce computational load, then processing speed is improved, but interpolation accuracy degrades and small gradation changes cannot be reproduced
Solution Approach 1:
The patent performs preliminary correction of gradation values using correction tables before the main color conversion process. By pre-processing the gray scale values and correcting potential interpolation errors in advance, the system compensates for the reduced lattice point density. This preliminary action ensures that even with thinned-out lattice points, the final color conversion maintains high accuracy.
Solution Approach 2:
The patent introduces correction tables as an intermediary component between the input image data and the 3D LUT color conversion. These correction tables serve as a mediator that adjusts gray scale values before they undergo interpolation, thereby compensating for the accuracy loss caused by reduced lattice point density and ensuring smooth gradation transitions.
3Productivity
If 1D LUTs are used to convert common one-dimensional components, then processing efficiency is improved, but stepwise color characteristics and small gradation changes smaller than lattice point intervals cannot be reproduced
Solution Approach 1:
The patent merges the advantages of both 1D LUT processing and 3D LUT color conversion by combining correction table processing with segmented 3D LUT conversion. The correction tables handle the efficient one-dimensional component conversion, while the segmented 3D LUTs preserve the three-dimensional color relationships and small gradation changes. This combination achieves both processing efficiency and high precision gradation reproduction.
Data Source
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AI summary
Provided are a color conversion method, gradation value correction device, computer program, and display device that can reproduce small gradation changes between lattice points, as well as can reduce accuracy degradation caused by interpolation. Dividing one of input gradations and output gradations of gradation characteristics, indicating input/output gradation characteristics reproduced in a second conversion unit, into gradation segments having predetermined gradation intervals. Then, correcting each of the gradation values of the other gradations of the gradation characteristics so that gradation intervals of the other gradations become intervals corresponding to the predetermined gradation intervals. The first conversion unit then converts the gradation values of an image using the corrected gradation values.