Luma Mapping With Chroma Scaling for Lower-Complexity Video Coding

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Solution Overview

Problem

The increasing demand for high-resolution, high-quality image/video data, particularly in immersive media formats like VR and AR, necessitates a highly efficient compression technology to reduce transmission and storage costs while maintaining subjective/objective visual quality.

Innovation Solution

Implementing luma mapping with chroma scaling (LMCS) processes that include efficient filtering, constrained codewords, linear mapping, and flexible bin usage, along with simplified inverse mapping index derivation to enhance image/video coding efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high-resolution, high-quality image/video data is transmitted or stored using existing broadband lines or storage media, then image quality is maintained, but transmission cost and storage cost increase

Engineering Contradiction:
Improveimage qualityVSAvoidtransmission cost and storage cost
Core Design Contradiction:
Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent applies luma mapping with chroma scaling (LMCS) to transform the parameter representation of image/video data. By mapping luma values to a reduced set of codewords and scaling chroma residuals, the patent changes how visual information is encoded, achieving high compression ratios while preserving perceived image quality

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies different processing strategies to different components of the image data: luma components undergo mapping to discrete codewords while chroma components undergo residual scaling. This local differentiation optimizes compression for each component based on its visual importance and characteristics

Inventive Principle:
Principle #3Local quality

2Productivity

If luma mapping with chroma scaling (LMCS) process is performed to improve compression efficiency and visual quality, then compression efficiency and visual quality increase, but computational complexity increases

Engineering Contradiction:
Improvecompression efficiencyVSAvoidcomputational complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the LMCS process into distinct stages: luma mapping to codewords, chroma residual calculation, and chroma scaling. This segmentation allows each stage to be optimized independently and enables selective application based on content characteristics

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent allows for selective application of full LMCS processing versus simplified versions. In some cases, only luma mapping is applied, or chroma scaling is omitted, providing a trade-off between compression efficiency and computational complexity based on specific content requirements

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS20250254343A1Luma mapping- and chroma scaling-based video or image coding
Publication Date: 2025.08.07 LG ELECTRONICS INC
  • US20250254343A1 patent drawing
  • US20250254343A1 patent drawing
  • US20250254343A1 patent drawing

AI summary

According to the disclosure of the present document, a luma mapping with chroma scaling (LMCS) process may be simplified, and a linear LMCS may be applied. Accordingly, the complexity of the LMCS may be reduced and video/image coding efficiency may be increased.