LMCS Video Coding Using Flexible Luma Bins and Single Chroma Scaling
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Solution Overview
Problem
The increasing demand for high-resolution, high-quality images/videos, such as 4K or 8K UHD, leads to higher data transmission and storage costs, and existing compression technologies struggle to efficiently compress and transmit these files, especially for immersive media like VR and AR content.
Innovation Solution
The implementation of an efficient Luma Mapping with Chroma Scaling (LMCS) method, which includes flexible bin usage for luma mapping, explicit signaling of pivot points, and a single chroma residual scaling factor, to enhance image/video coding efficiency and reduce resource requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-resolution, high-quality image/video data is transmitted or stored, then visual quality is improved, but transmission cost and storage cost increase
Solution Approach 1:
The patent applies parameter changes by transforming the luminance component through piecewise linear mapping with different bins, and scaling the chroma component using chroma residual scaling. This changes the parameter representation of the image data to achieve better compression efficiency while maintaining visual quality, thereby reducing transmission and storage costs.
Solution Approach 2:
The patent segments the luminance component into multiple bins (e.g., 16 bins) and applies different mapping strategies to each bin. This segmentation allows selective compression where needed, improving overall compression efficiency without sacrificing visual quality in important regions.
2Productivity
If complex compression algorithms are used to improve compression efficiency, then coding efficiency is improved, but device complexity increases
Solution Approach 1:
The patent uses parameter changes through piecewise linear mapping and chroma residual scaling, which are computationally efficient transformations. These methods improve compression efficiency without requiring complex algorithms, thus resolving the contradiction between compression efficiency and device complexity.
Solution Approach 2:
The patent applies partial action by selectively applying chroma residual scaling only when needed (e.g., when chroma components have significant residual energy), rather than always applying full complex processing. This maintains compression efficiency while reducing unnecessary computational complexity.
3Productivity
If multiple chroma residual scaling factors are used in LMCS, then compression efficiency is improved, but signaling overhead and processing time increase
Solution Approach 1:
The patent extracts and uses a single chroma residual scaling factor instead of multiple factors. This simplification reduces the signaling overhead and processing time required for LMCS while maintaining adequate compression efficiency, thus resolving the contradiction between compression efficiency and processing time.
Solution Approach 2:
The single chroma residual scaling factor serves multiple functions: it scales chroma residuals across different bins, handles various chroma component types (Cb, Cr), and works universally across different image regions. This multi-functionality eliminates the need for multiple specialized scaling factors, reducing processing complexity and time.
Data Source
AI summary
According to the disclosure of the present document, a linear reshaper is used for LMCS and a single chroma residual scaling factor, which is directly signaled during chroma scaling of the LMCS, can be used. In addition, the number of flexible bins can be used for luma mapping so that the resource/cost (of software or hardware) required for an LMCS procedure is minimized, and the latency of coding is removed so that the LMCS procedure can be efficiently performed.