Tone Mapper Chroma Clipping Prevention via Segmented Color Correction
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Solution Overview
Problem
Current SL-HDRx systems face challenges in avoiding chroma clipping during the conversion of HDR to SDR, which leads to reconstruction errors and desaturated images that lose hue consistency with the original HDR signal.
Innovation Solution
A method and device that segment luminance values into partial ranges, estimate attenuation values to prevent clipping, and adjust the color correction function to maintain saturation and hue by computing and applying correction factors across luminance ranges, ensuring the chroma components are not clipped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chroma components are attenuated to avoid clipping during HDR to SDR conversion, then chroma clipping is prevented, but saturation and hue consistency deteriorate
Solution Approach 1:
The luminance range is segmented into multiple partial luminance ranges, and the color correction function is adjusted separately for each segment. This allows selective attenuation of chroma components only in specific luminance regions where clipping occurs, while preserving saturation and hue in other regions. The method divides the problem into manageable segments rather than applying uniform attenuation across all luminance values.
Solution Approach 2:
Different attenuation factors are applied to different luminance segments based on local requirements. The color correction function is modified locally for each partial luminance range rather than applying a global attenuation factor. This ensures that chroma clipping is prevented only where necessary, while maintaining optimal saturation and hue consistency in regions where clipping does not occur.
2Device complexity
If a single color correction function is used for HDR to SDR conversion, then processing is simplified, but chroma clipping cannot be avoided in all luminance regions
Solution Approach 1:
The color correction function is segmented into multiple adjustments corresponding to different partial luminance ranges. Each segment has its own correction parameters that can be independently optimized. This segmentation approach balances complexity by breaking down the problem into smaller, more manageable parts while achieving comprehensive chroma clipping prevention across all luminance regions.
Solution Approach 2:
The color correction function becomes dynamic and adaptive to different luminance conditions. Rather than using a static single correction function, the system dynamically selects and applies appropriate correction parameters based on the local luminance range of each pixel. This dynamic approach enables effective chroma clipping prevention while maintaining processing efficiency through predefined correction tables.
Data Source
AI summary
A method comprising modifying a color correction function intended to correct initial chroma components of a current image to obtain normalized corrected chroma components for avoiding the clipping of the initial chroma components while maintaining saturation and preserving hue.