Chroma Intra Prediction Mode Mapping for Video Coding Efficiency
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Solution Overview
Problem
Current video coding technologies face challenges in achieving improved compression ratios with minimal sacrifice in picture quality, particularly in chroma intra prediction mode derivation for chroma subsampling formats like 4:2:2 and 4:2:0, which affect encoding efficiency.
Innovation Solution
A method and apparatus for deriving more accurate mapping relationships between intra prediction modes for chroma components, specifically for chroma subsampling formats, by obtaining and decoding chroma format indication information and using predefined mapping tables to determine mapped intra prediction mode values, thereby enhancing coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chroma intra prediction mode derivation uses conventional mapping relationships, then encoding complexity is reduced, but coding efficiency and compression ratio deteriorate
Solution Approach 1:
The patent changes the mapping relationship parameters between luma and chroma intra prediction modes based on chroma subsampling format (4:2:0, 4:2:2, 4:4:4). Different mapping tables are used for different subsampling formats, optimizing the mapping relationship to improve coding efficiency while maintaining manageable encoding complexity through standardized tables.
Solution Approach 2:
The patent applies different mapping relationships locally according to the specific chroma subsampling format being used. Instead of a universal mapping, the system selects appropriate mapping tables based on the local chroma format characteristics, thereby improving coding efficiency for each specific case without universally increasing complexity.
2Measurement precision
If chroma intra prediction mode uses simple mapping from luma mode, then device complexity is reduced, but measurement precision of mapping relationship deteriorates
Solution Approach 1:
The patent modifies the mapping relationship parameters to account for chroma subsampling format differences. By changing the mapping table based on the subsampling format (4:2:0, 4:2:2, 4:4:4), the system achieves more accurate mapping relationships that reflect the actual chroma component characteristics, thereby improving measurement precision without excessive complexity increase.
Solution Approach 2:
The patent introduces chroma format indication information as an intermediary parameter that mediates between luma intra prediction mode and chroma intra prediction mode. This intermediary enables more precise mapping by considering the specific chroma format, improving accuracy while keeping the derivation process manageable through standardized format indicators.
3Productivity
If video data is compressed heavily to improve compression ratio, then bandwidth usage is reduced, but picture quality deteriorates
Solution Approach 1:
The patent optimizes the chroma intra prediction mode derivation parameters based on chroma subsampling format to improve compression ratio. By using format-specific mapping relationships, the system achieves better prediction accuracy for chroma components, enabling more efficient compression while maintaining picture quality through improved chroma reconstruction.
Solution Approach 2:
The patent applies local optimization to chroma component compression by using different prediction strategies for different chroma subsampling formats. This local quality approach ensures that compression is optimized for each specific format (4:2:0, 4:2:2, 4:4:4) without sacrificing overall picture quality, as each format receives appropriately tailored prediction processing.
Data Source
AI summary
A method of coding implemented by a decoding device, comprising obtaining a video bitstream; decoding the video bitstream to obtain an initial intra prediction mode value for chroma component of a current coding block; determining whether a ratio between a width for luma component of the current coding block and a width for chroma component of the current coding block is equal to a threshold or not; obtaining a mapped intra prediction mode value for chroma component of the current coding block according to a predefined mapping relationship and the initial intra prediction mode value, when it's determined that the ratio is equal to the threshold; obtaining a prediction sample value for chroma component of the current coding block according to the mapped intra prediction mode value.