ISP Residual Signal Encoding with Transform Skip Mode
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Solution Overview
Problem
The increasing demand for high-resolution and high-quality images, such as HD and UHD, leads to a significant increase in the amount of transmitted and stored information, resulting in higher transmission and storage costs, necessitating the development of high-efficient image compression technologies.
Innovation Solution
An image encoding/decoding method and apparatus that utilizes intra sub-partitions (ISP) and transform skip mode to efficiently encode and decode residual signals, optimizing context models, transform subblock sizes, scan methods, and syntax element encoding/decoding based on block characteristics, thereby improving encoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution and high-quality images are transmitted, then image quality is improved, but transmission cost and storage cost increase
Solution Approach 1:
The current block is divided into multiple transform subblocks for independent processing. The transform skip mode is applied selectively to different subblocks based on their characteristics, allowing fine-grained control over compression efficiency and quality distribution across the image block.
Solution Approach 2:
Different processing modes are applied to different regions within a block. The transform skip mode is enabled or disabled based on local characteristics such as gradient magnitude, allowing important regions to maintain higher quality while less important regions achieve greater compression.
2Productivity
If transform skip mode is applied to residual signals, then encoding efficiency is improved, but decoding complexity increases
Solution Approach 1:
The transform skip mode is dynamically selected based on block characteristics rather than being fixed. The encoder evaluates gradient magnitude and other features to determine whether to apply transform skip mode, adapting the processing strategy to match the local content characteristics.
Solution Approach 2:
The system uses inherent properties of the residual signal itself (such as gradient magnitude) to make encoding decisions. The signal's own characteristics guide whether transform skip mode should be applied, eliminating the need for external complex analysis.
3Measurement precision
If context models are optimized for ISP blocks, then encoding precision is improved, but model complexity increases
Solution Approach 1:
Separate context models are maintained for different block types (ISP vs. non-ISP). The decoder determines the block type and selects the appropriate context model, allowing each model to be optimized for its specific block characteristics without requiring a single complex universal model.
Solution Approach 2:
The context model parameters are changed based on the block type. When an ISP block is detected, a specific context model configuration is applied; otherwise, a different configuration is used. This allows precise encoding for each block type while keeping the overall system manageable through conditional parameter selection.
Data Source
AI summary
An image encoding/decoding method and apparatus are provided. The image decoding method includes determining whether a prediction mode of a current block is an intra prediction mode based on information on the prediction mode of the current block, determining whether a transform mode of the current block is a transform skip mode, determining whether an intra prediction technique of the current block is intra sub-partitions (ISP) based on the prediction mode of the current block being an intra prediction mode, and generating a transform coefficient block of the current block based on the transform mode of the current block and whether the intra prediction technique of the current block is ISP.