Shape-Adaptive Context Coding for Transform Coefficients
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image and video coding schemes face inefficiencies in entropy coding of transform coefficients due to inadequate consideration of the spatial and temporal redundancy in video content, particularly in determining the context for syntax elements associated with transform coefficients.
Innovation Solution
A method and device for entropy coding and decoding that determine the context for syntax elements based on the area of the block, the position of the transform coefficient within the block, and the number of non-zero neighboring transform coefficients in a local template, where the local template depends on the shape of the block, enhancing the entropy coding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed local template is used for context determination, then the device complexity is reduced, but the coding efficiency deteriorates due to inadequate adaptation to different block shapes
Solution Approach 1:
The local template is made dynamic by adapting its shape and size to the current block being processed. The template dimensions are adjusted based on the block's width and height, allowing the context determination to dynamically match the geometric characteristics of different blocks, thereby improving coding efficiency without requiring complex manual configuration
Solution Approach 2:
Different regions of the transform coefficient block are treated with different local templates appropriate to their shape characteristics. Each block uses a locally optimized template that matches its specific geometry, ensuring that context determination is tailored to local block properties rather than applying a uniform approach everywhere
2Measurement precision
If the local template size is increased to capture more neighboring coefficients, then the measurement precision of context determination is improved, but the loss of information increases due to potential inclusion of irrelevant distant coefficients
Solution Approach 1:
The template dimensions are adjusted as parameters based on the block size. For larger blocks, larger templates are used to capture sufficient neighboring context, while for smaller blocks, smaller templates are used to avoid including irrelevant distant coefficients. This parameter adaptation ensures optimal template size for each specific block, balancing context capture with relevance
3Manufacturing precision
If context determination is based on multiple factors (block area, position, neighboring coefficients), then the entropy coding accuracy is improved, but the computational complexity increases
Solution Approach 1:
The context determination process is segmented into distinct steps: first determining block geometry parameters, then calculating template dimensions, next counting non-zero neighboring coefficients within the template, and finally using these to determine the context. This segmentation breaks down the complex multi-factor determination into manageable stages, improving accuracy while controlling computational complexity through systematic organization
Data Source
AI summary
A decoding method is disclosed. First, context for a syntax element associated with a current transform coefficient of a block of a picture is determined. The context is determined based on the area of said block, on the position of the current transform coefficient within the block and on the number of non-zero neighboring transform coefficients in a local template. Second, the syntax element is decoded based at least on the determined context. Advantageously, the local template depends on the shape of said block.