Joint Tone Mapping for Balanced Local Detail and Image Contrast
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Solution Overview
Problem
Existing tone mapping methods, including global and local tone mapping, fail to effectively balance overall contrast and local details, resulting in unsatisfactory image display effects due to uncoordinated regional contrasts and poor coordination.
Innovation Solution
A tone mapping method combining global and local tone mapping, where initial local tone mapping curves are adjusted based on feature values to meet specific conditions, ensuring luminance and darkness consistency, thereby balancing regional contrasts and improving overall image display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If local tone mapping is performed on pixels at different locations, then local image details are improved, but global contrast coordination deteriorates
Solution Approach 1:
The patent applies local tone mapping to specific regions of the image based on their luminance characteristics. Different tone mapping curves are applied to different regions (bright regions, dark regions, and intermediate regions) to optimize local details while maintaining overall image quality. This resolves the contradiction by making the tone mapping adaptive to local characteristics rather than uniform across the entire image.
Solution Approach 2:
The image is segmented into multiple regions based on luminance characteristics (bright regions with luminance above a first threshold, dark regions with luminance below a second threshold, and intermediate regions). Each segment receives appropriate tone mapping processing, allowing local details to be enhanced while maintaining global contrast coordination through region-specific processing.
2Stability of the object's composition
If global tone mapping is applied to the entire image, then overall luminance consistency is improved, but local contrast and details deteriorate
Solution Approach 1:
The image is divided into multiple luminance-based regions, and different tone mapping strategies are applied to each segment. Bright regions use one mapping approach, dark regions use another, and intermediate regions use a third. This segmentation allows the preservation of overall luminance consistency while enhancing local contrast and details in each region appropriately.
Solution Approach 2:
Different tone mapping curves and processing parameters are applied to different regions based on their luminance characteristics. This local quality approach ensures that each region receives optimized processing for its specific characteristics, preserving local details and contrast while maintaining overall image consistency.
3Adaptability or versatility
If tone mapping is performed to match display device luminance range, then display compatibility is improved, but image dynamic range information is lost
Solution Approach 1:
The patent employs multiple tone mapping curves with different parameters optimized for different luminance ranges. By selecting and applying appropriate curves based on regional luminance characteristics, the system maintains display compatibility across different devices while preserving as much luminance range information as possible through adaptive parameter selection rather than uniform compression.
Data Source
AI summary
This disclosure provides a tone mapping method and apparatus. In the method, after global tone mapping is performed on a to-be-displayed image, local mapping information is adjusted to obtain the adjusted local mapping information; and based on the adjusted local mapping information, local tone mapping is performed on at least some pixels in the to-be-displayed image on which global tone mapping is performed. In embodiments of this disclosure, a global and local joint tone mapping solution is used, and local mapping is performed based on the adjusted local mapping information, to balance an uncoordinated contrast between different regions in local tone mapping, and effectively improve tone mapping effect and display effect of an image.