Sub-Block Inverse Transform Selection for Video Coding Efficiency
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Solution Overview
Problem
The increasing demand for high-definition video services has led to a significant increase in data volume, and existing video compression standards like HEVC are showing limitations in performance.
Innovation Solution
A method for partitioning coding blocks into sub-blocks and applying a second transform based on block size and intra prediction mode, with the application of a second inverse transform determined by index information signaled via a bitstream, allowing for improved encoding/decoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single transform is applied to coding blocks, then the encoding process is simple, but the compression performance is insufficient for high-definition video services
Solution Approach 1:
The coding block is divided into multiple sub-blocks, and different transforms are applied to different sub-blocks based on their characteristics. This segmentation allows the system to achieve better compression performance by tailoring the transform to local regions while maintaining overall process manageability through structured division.
Solution Approach 2:
The system dynamically selects whether to apply a first transform or a second transform to each sub-block based on the intra prediction mode and other factors. This dynamic adaptability enables the encoder to optimize compression performance for high-definition video services while managing complexity through conditional application rather than fixed multi-step processing.
2Productivity
If multiple transforms are applied to sub-blocks, then encoding/decoding efficiency is improved, but the complexity of determining transform application increases
Solution Approach 1:
The system uses parameter changes (intra prediction mode values, block size thresholds) to determine transform application. By changing the parameters used for decision-making based on the specific characteristics of each sub-block, the system achieves efficient encoding/decoding while managing complexity through clear, parameter-based decision rules rather than complex algorithms.
Solution Approach 2:
The system performs preliminary analysis of the coding block characteristics (intra prediction mode, block size) before determining transform application. This preliminary action allows the encoder to pre-determine the appropriate transform strategy, improving encoding/decoding efficiency while reducing the complexity of real-time decision-making by using pre-established criteria.
3Device complexity
If transform application is determined by block size threshold, then the decision process is simplified, but smaller blocks may not receive optimal transform treatment
Solution Approach 1:
The system applies different transform strategies to different sub-blocks based on their local characteristics (intra prediction mode, size). Rather than applying a uniform threshold-based decision, the system evaluates each sub-block's specific properties to determine the most appropriate transform, ensuring optimal compression efficiency for small blocks while maintaining simple decision logic through localized analysis.
Data Source
AI summary
A method for decoding an image according to the present invention comprises the steps of: partitioning a coding block into a plurality of sub-blocks in a horizontal direction or vertical direction; determining whether a second inverse transform is applied to the coding block; and when it is determined that the second inverse transform is applied to the coding block, applying the second inverse transform to at least one of the plurality of sub-blocks.