Chroma Mode Lists for Efficient Image Intra Prediction
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Solution Overview
Problem
The increasing demand for high-resolution, high-quality images leads to higher data volumes, resulting in increased transmission and storage costs due to existing image encoding/decoding technologies being inefficient.
Innovation Solution
An image encoding/decoding method that includes generating a chroma mode list comprising default, derivation-based, and direct modes, using reconstructed pixels of collocated luma blocks and neighboring reference pixels to derive chroma intra prediction modes, and generating prediction blocks based on these modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing image encoding/decoding technology is used, then transmission and storage can be performed, but transmission and storage costs increase due to inefficient compression
Solution Approach 1:
The patent introduces an intermediary chroma mode list that mediates between the luma block prediction mode and the chroma block prediction mode. This list includes multiple candidate modes (direct mode, derivation based chroma mode, and default mode) that are derived from the luma block's prediction mode. The intermediary list allows the decoder to efficiently select the most appropriate chroma prediction mode without requiring explicit signaling of multiple modes, thereby improving encoding/decoding efficiency while reducing data volume.
Solution Approach 2:
The patent changes the parameter representation by deriving chroma prediction modes from luma prediction modes through a chroma mode list. Instead of independently encoding chroma prediction modes, the system transforms the chroma mode selection into a parameter derived from the luma block's prediction mode. This parameter transformation reduces the bitrate required for chroma encoding while maintaining prediction accuracy, thus addressing the contradiction between efficiency and data volume.
2Manufacturing precision
If high-resolution, high-quality images are transmitted or stored, then image quality improves, but transmission and storage costs increase
Solution Approach 1:
The chroma mode list acts as an intermediary mechanism that enables high-quality chroma prediction by leveraging the already-encoded luma block information. By deriving chroma prediction modes from luma prediction modes through the intermediary list, the system maintains high image quality for high-resolution images without proportionally increasing data volume, thus resolving the contradiction between image quality and data volume.
Solution Approach 2:
The chroma mode list serves multiple functions: it provides default prediction modes, derives prediction modes from luma blocks, and adapts to different chroma formats (4:2:0, 4:4:4). This multi-functionality allows the same mechanism to maintain high image quality across different resolutions and formats while efficiently managing data volume through unified prediction mode derivation.
Data Source
AI summary
An image encoding/decoding method and apparatus, a recording medium for storing a bitstream and a transmission method are provided. The image decoding method comprises generating a chroma mode list of a current chroma block, deriving a chroma intra prediction mode of the current chroma block based on the chroma mode list, and generating a prediction block of the current chroma block based on the chroma intra prediction mode. The chroma mode list may comprise at least one of a default mode, a derivation based chroma mode or a direct mode.