Color Gamut Mapping Preserving Gradients for UHD to HD Conversion
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Solution Overview
Problem
Higher definition settings like UHD require additional resources and processing, leading to distortion when displayed on HD or SD devices due to clipping techniques, which compromise the viewing experience.
Innovation Solution
A method and apparatus for color gamut mapping that preserves color gradients by converting UHD images to HD or SD formats, using a gamut mapping color gradient preservation table to maintain hue and luminance values while adjusting chroma values within the display device's capabilities, employing linear or curve-based compression ratios to ensure perceptual color accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If clipping technique is used to map UHD colors to HD color gamut, then UHD content can be displayed on HD devices, but image distortion occurs and viewing experience deteriorates
Solution Approach 1:
The patent changes the mapping parameters from simple clipping (mapping out-of-gamut colors to boundary colors) to gradient-preserving mapping. It uses a gamut mapping table that stores chroma values for different hue and luminance combinations, allowing continuous color gradient preservation while adapting UHD content to HD display capabilities.
Solution Approach 2:
The patent introduces a gamut mapping table as an intermediary data structure between the UHD source content and the HD display. This table contains pre-calculated chroma values that mediate the color transformation, preserving gradients while ensuring compatibility with the target display's color gamut.
2Measurement precision
If 10 or 12 bit RGB channel values are used for UHD content, then color precision is improved, but processing complexity increases for displays with limited capabilities
Solution Approach 1:
The patent segments the color space into discrete hue and luminance levels, creating a gamut mapping table with indexed entries. This segmentation allows the system to handle high-precision color data through lookup operations rather than complex real-time calculations, reducing processing complexity while maintaining color precision.
Solution Approach 2:
The patent performs preliminary calculation of the gamut mapping table, pre-computing the chroma values for various hue and luminance combinations. This preliminary action transfers the processing complexity from runtime display operations to an offline table generation phase, enabling efficient real-time color mapping on resource-constrained devices.
3Manufacturing precision
If chroma values are adjusted to fit target color gamut, then color gradient perception is preserved, but processing time increases
Solution Approach 1:
The patent performs the complex chroma adjustment calculations in advance during gamut mapping table generation. By pre-computing the chroma values for all hue and luminance combinations, the system eliminates time-consuming runtime calculations, enabling fast real-time color mapping while preserving gradient perception.
Solution Approach 2:
Instead of adjusting chroma values in real-time during display, the patent inverts the approach by pre-calculating and storing the adjusted chroma values in a lookup table. This inversion transforms a computationally intensive real-time operation into a simple memory retrieval operation during actual display.
Data Source
AI summary
A method and apparatus for gamut mapping color gradient preservation is described. In one example, the method and apparatus obtains a source image having a plurality of source color gamut pixels in a source color gamut, wherein the plurality of source color gamut pixels include a same hue value and a same luminance value and define a color gradient, and converts the plurality of source color gamut pixels to a plurality of target color gamut pixels such that the color gradient of the plurality of source color gamut pixels is preserved by the plurality of target color gamut pixels in a target color gamut. The method and apparatus provides the plurality of target color gamut pixels for display on a target color gamut display.