Low Dynamic Range Image Grey-Level Adjustment for High Dynamic Range Output
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Solution Overview
Problem
Low dynamic range images struggle to accurately represent real brightness and suffer from image information loss due to saturation, limiting their display quality and compatibility with high dynamic range systems.
Innovation Solution
A method involving grey-level adjustment through inverse-gamma correction and enhancement, specifically using formulas to adjust and compress pixel values, followed by grey-level enhancement of saturation areas to produce a high dynamic range image, addressing the limitations of low dynamic range images by improving brightness and reducing information loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If low dynamic range images are used to represent brightness, then the image can be displayed on standard devices, but the image information is lost due to saturation and the brightness representation is inaccurate
Solution Approach 1:
The patent transforms the image data from low dynamic range (8-bit) to high dynamic range (10-bit or higher) by changing the parameter of color depth. This allows the image to represent a wider range of brightness values (dynamic range >1000:1) without saturation, thereby reducing information loss and improving brightness representation accuracy while maintaining compatibility through inverse-gamma mapping
2Illumination intensity
If inverse-gamma mapping is applied to convert low dynamic range image to high dynamic range image, then the brightness can be improved, but blocking phenomena occur during the mapping process
Solution Approach 1:
The patent segments the image processing into distinct stages: first applying inverse-gamma mapping to convert from low to high dynamic range, then performing grey-level adjustment, and finally selecting and enhancing saturation areas separately. This segmentation allows brightness improvement while managing the blocking phenomenon through controlled processing stages
Solution Approach 2:
The patent applies different processing quality to different regions of the image. After inverse-gamma mapping, it identifies saturation areas (where grey-level value ≥ threshold) and applies grey-level enhancement specifically to these regions. This local quality approach improves overall brightness while managing mapping artifacts by treating saturated and non-saturated regions differently
3Adaptability or versatility
If the pixel value reaches maximum grey-level value in low dynamic range image, then the image can be displayed on 8-bit systems, but the saturation occurs and image information is lost
Solution Approach 1:
The patent transitions from an 8-bit color depth dimension to a 10-bit or higher color depth dimension. This dimensional change allows the system to represent brightness values beyond the 0-255 range of 8-bit systems, enabling high dynamic range (>1000:1) representation without saturation while maintaining compatibility with standard 8-bit display systems through the inverse-gamma mapping process
Data Source
AI summary
The present disclosure provides a method for generating a high dynamic range image from a low dynamic range image, including performing grey-level adjustment on a low dynamic range image to be processed in accordance with a preset mapping relationship to obtain an image after the grey-level adjustment, the grey-level adjustment includes inverse-gamma correction and grey-level value increase; selecting a plurality of saturation areas in the image after the grey-level adjustment; performing grey-level enhancement of the saturation areas in the image after the grey-level adjustment, to obtain a target high dynamic range image; and outputting the target high dynamic range image.