Color Conversion Using Segmented 1D and 3D Lookup Tables
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Solution Overview
Problem
Existing color conversion technologies face challenges in accurately processing over-range colors without sacrificing processing speed, particularly when dealing with devices that have limited color gamuts like sRGB, as they often require large three-dimensional look-up tables (3D LUTs) that can be unmanageable or result in loss of data.
Innovation Solution
The method involves dividing the input range of color component values into sub-ranges, determining accuracy levels for each sub-range, and using a combination of one-dimensional (1D) and three-dimensional (3D) look-up tables to convert colors, with the 1D LUT determining the number of grid points in the 3D LUT based on desired accuracy, allowing for flexible accuracy handling and manageable table sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large three-dimensional look-up tables (3D LUTs) are used to accurately process over-range colors, then color conversion accuracy is improved, but device complexity and memory requirements increase significantly
Solution Approach 1:
The patent segments the color conversion process into two distinct stages: a first color conversion using a simplified method (formula-based or reduced LUT) to bring over-range colors into the target gamut, followed by a second color conversion using a 3D LUT to achieve final high-accuracy conversion. This segmentation allows the large 3D LUT to be avoided or reduced in size while maintaining overall conversion accuracy.
Solution Approach 2:
The patent performs preliminary color conversion before the main 3D LUT conversion step. By first converting over-range colors using formulas or a reduced LUT to bring them within the target gamut range, the system prepares the data in advance so that the subsequent 3D LUT operation can be performed with smaller, more manageable table sizes while still achieving accurate results.
2Measurement precision
If more grid points are used in the 3D LUT to increase conversion accuracy, then color conversion precision is improved, but processing time increases
Solution Approach 1:
The patent divides the conversion process into two phases: a preliminary conversion phase using computationally efficient formulas or reduced LUTs, and a final conversion phase using the 3D LUT. This segmentation allows the system to achieve high accuracy without requiring the 3D LUT to handle all conversion scenarios, thereby reducing the effective complexity and processing burden of the LUT operations.
Solution Approach 2:
The patent changes the parameters of the color values through preliminary conversion operations (using formulas or reduced LUTs) before applying the 3D LUT. By transforming the input color values to bring them within the target gamut range first, the system enables the use of smaller, faster 3D LUT structures while maintaining the ability to accurately represent the full range of colors.
3Measurement precision
If over-range color values are processed with high accuracy, then color fidelity is improved, but processing speed decreases
Solution Approach 1:
The patent segments the processing pipeline into a speed-optimized preliminary conversion stage and an accuracy-optimized final conversion stage. The preliminary stage uses computationally lightweight operations (formulas or reduced LUTs) to handle over-range colors efficiently, while the final stage applies the 3D LUT to achieve high-fidelity conversion, thereby balancing overall processing speed and accuracy.
Solution Approach 2:
The patent performs preliminary color space transformation and gamut mapping using efficient algorithms before the main 3D LUT conversion. This preliminary action reduces the complexity of subsequent LUT operations and enables real-time processing of over-range colors while maintaining high fidelity in the final output.
Data Source
AI summary
A method includes dividing an input range of color values of a first color space into a plurality of sub-ranges, wherein at least one of the sub-ranges comprises an over-range color value. The method also includes determining for each sub-range a level of accuracy in converting color values within each sub-range. The method further includes determining a processing step to be applied to input color values in each sub-range based on the determined level of accuracy.