Intra Prediction Mode Encoding Using Neighbor-Based VLC Selection
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Solution Overview
Problem
Existing image compression technologies face challenges in efficiently encoding and decoding high-definition and ultra-high-definition images, particularly in optimizing intra prediction modes for improved encoding/decoding efficiency.
Innovation Solution
The method involves deriving neighbor prediction mode information from left and upper neighbor units to determine the intra prediction mode for a decoding target unit, using angular difference and mode number information to select context models and variable length coding tables for entropy encoding/decoding, and generating a most probable mode list to enhance encoding/decoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional intra prediction encoding is used, then encoding simplicity is maintained, but encoding efficiency and compression performance deteriorate for high-definition and ultra-high-definition images
Solution Approach 1:
The patent applies preliminary action by pre-defining a Most Probable Mode (MPM) list containing candidate intra prediction modes before actual encoding. The encoder prepares multiple candidate modes (e.g., planar, DC, and angular modes) in advance, and the decoder can select from these pre-prepared options, reducing the search space and improving encoding efficiency without requiring complex real-time analysis
Solution Approach 2:
The patent changes parameters by introducing mode difference values and offset calculations. Instead of directly encoding absolute mode indices, the system encodes differences between neighboring block modes and current block modes, using offset tables to map these differences to actual prediction modes. This parameter transformation enables more efficient entropy coding while maintaining prediction accuracy
2Measurement precision
If more intra prediction modes are considered to improve accuracy, then prediction precision improves, but bit stream size and processing overhead increase
Solution Approach 1:
The patent applies local quality by selecting different MPM list configurations and mode difference encoding strategies based on local characteristics of neighboring blocks. The system adapts the number of candidate modes and the type of mode differences encoded according to the specific spatial context, using only the necessary precision for each local region rather than uniformly high precision everywhere
Solution Approach 2:
The patent uses partial action by encoding only the difference between modes rather than full mode information. The system encodes partial mode information (mode differences) that, when combined with the MPM list, reconstructs the complete prediction mode. This partial encoding approach reduces bit stream size while maintaining the ability to represent all necessary prediction modes
3Productivity
If context models and VLC tables are selected without considering neighbor prediction modes, then encoding speed is maintained, but compression performance deteriorates
Solution Approach 1:
The patent implements feedback by using neighbor block prediction modes to inform the selection of context models and VLC tables for the current block. The encoding process feeds back information from previously encoded neighboring blocks to guide the encoding of the current block, creating an adaptive system that improves compression performance based on local statistical patterns
Solution Approach 2:
The patent changes parameters by dynamically selecting context model indices and VLC table types based on neighbor prediction mode characteristics. The system transforms neighbor mode information into parameters that control entropy coding behavior, such as selecting from multiple VLC tables or adjusting context model probabilities, thereby adapting the encoding process to local image characteristics
Data Source
AI summary
Disclosed herein is an intra prediction method including: deriving neighbor prediction mode information from a left neighbor prediction mode and an upper neighbor prediction mode; deriving an intra prediction mode for a decoding target unit by using the derived neighbor prediction mode information; and performing intra prediction on the decoding target unit based on the intra prediction mode. According to exemplary embodiments of the present invention, image encoding/decoding efficiency can be improved.