Image Processing Circuit Gamma Table Compensation
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Solution Overview
Problem
Liquid crystal displays (LCDs) suffer from the off-angle viewing problem, leading to color distortion and grid phenomenon due to the use of different gamma lookup tables for neighboring pixels, which reduces visual experience.
Innovation Solution
An image processing circuit and method that receives pixels and assigns them to either a gamma-high or gamma-low category, using distinct gamma tables for each category to compensate pixel values, ensuring that pixels at different locations can have different gamma tables even if they share the same category, thereby mitigating the grid phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If different gamma LUTs are applied to neighboring pixels to mitigate off-angle viewing problem, then off-angle viewing quality is improved, but grid phenomenon appears in the image
Solution Approach 1:
The patent applies different gamma tables to different pixel locations based on their coordinates. Specifically, pixels at even coordinate positions use one gamma table while pixels at odd coordinate positions use another gamma table. This local differentiation approach mitigates off-angle viewing problems by providing location-specific compensation while avoiding the grid phenomenon that occurs when identical gamma tables are applied to all pixels of the same category.
2Object-generated harmful factors
If identical gamma LUTs are applied to all pixels, then grid phenomenon is avoided, but off-angle viewing problem persists
Solution Approach 1:
The patent implements location-dependent gamma compensation where the gamma table selection is determined by pixel coordinates. Even-positioned pixels and odd-positioned pixels are assigned different gamma tables from respective sets, enabling localized optimization for off-angle viewing without creating the harmful grid pattern that would result from uniform gamma application across all pixels.
3Manufacturing precision
If multiple gamma tables are used for different pixel locations, then compensation precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the pixel array into segments based on coordinate positions (even and odd positions). This segmentation allows the use of multiple gamma tables for different locations while maintaining manageable complexity through systematic organization. The gamma tables are stored in separate memory structures (first gamma table memory and second gamma table memory), enabling efficient access and reducing the complexity of managing multiple gamma tables compared to a fully arbitrary assignment scheme.
Data Source
AI summary
The image processing circuit includes a receiving circuit, configured to receive a plurality of pixels of a video frame, wherein the plurality of pixels are corresponding to a plurality of pixel locations, a pixel location of a pixel is corresponding to a gamma category value, and the gamma category value is either a gamma-high value or a gamma-low value; and a gamma table circuit, configured to obtain a gamma table; and a compensation circuit, configured to generate an output pixel value; wherein a plurality of first pixel locations are corresponding to a plurality of gamma-high tables, and the plurality of gamma-high tables are mutually different; wherein a plurality of second pixel locations are corresponding to a plurality of gamma-low tables, and the plurality of gamma-low tables are mutually different.