Luma Mapping Chroma Scaling Video Coding Efficiency
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Solution Overview
Problem
The increasing demand for high-resolution, high-quality images and videos, such as 4K or 8K, poses challenges in efficient compression, transmission, storage, and reproduction due to the high amount of information required, leading to increased costs and resource utilization.
Innovation Solution
The implementation of efficient luma mapping with chroma scaling (LMCS) methods, including constrained LMCS codewords, single chroma residual scaling factors, linear mapping, explicit signaling of pivot points, flexible bin usage for luma mapping, and simplified index derivation procedures for inverse luma mapping and chroma residual scaling, to enhance image/video coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution, high-quality image/video (4K or 8K) is transmitted or stored using existing methods, then image quality is improved, but transmission cost and storage cost increase due to high amount of information
Solution Approach 1:
The patent applies luma mapping with chroma scaling (LMCS) to transform the parameter distribution of image data. By mapping luma values to a different range and scaling chroma residuals, the method changes the statistical parameters of the data to achieve better compression characteristics, reducing the quantity of information needed to represent the same image quality
Solution Approach 2:
The patent segments the image processing into separate components: luma mapping is applied to luminance values while chroma scaling is applied to chrominance residuals. This segmentation allows independent optimization of each color component's compression, efficiently reducing total information quantity while preserving perceptual quality
2Productivity
If luma mapping with chroma scaling (LMCS) procedure is performed to improve compression efficiency and visual quality, then compression efficiency is improved, but computational complexity increases
Solution Approach 1:
The patent performs luma mapping as a preliminary action before chroma scaling. By first transforming the luma values and establishing the mapping relationship, subsequent chroma residual scaling can be performed more efficiently using pre-computed parameters, reducing overall computational complexity while maintaining compression efficiency
Solution Approach 2:
The patent introduces intermediate parameters (lmcs_cw and lmcs_cr) as mediators between the original image data and the compressed representation. These intermediate values facilitate the transformation process by providing structured intermediate representations that simplify subsequent processing steps
3Measurement precision
If accurate LMCS procedure is implemented to increase visual quality, then subjective/objective visual quality is improved, but processing time and resource utilization increase
Solution Approach 1:
The patent applies partial action by selectively processing only the chroma residual components after luma mapping, rather than reprocessing all image data. This partial processing approach achieves the necessary visual quality improvement while minimizing additional processing time and resource utilization
Data Source
AI summary
According to the disclosure of the present document, a chroma residual scaling factor is derived on the basis of information relating to an absolute value of a chroma residual scaling delta value and information relating to a sign of the chroma residual scaling delta value, and an LMCS procedure can be efficiently performed by applying explicit signaling to information relating to a value(s) of the chroma residual scaling factor.