NSPT Kernel Selection for Efficient Image Block Decoding
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Solution Overview
Problem
Existing image compression technologies face challenges in efficiently compressing high-resolution and high-quality images, particularly in determining and signaling non-separable transform kernels for improved encoding efficiency.
Innovation Solution
The method and apparatus utilize a non-separable primary transform (NSPT) kernel of reduced dimension, determining an NSPT set for a current block based on an encoding parameter, and applying it to derive transform coefficients and residual samples for improved encoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-separable primary transform (NSPT) is applied to improve encoding efficiency, then compression performance is improved, but device complexity increases
Solution Approach 1:
The patent divides the transform process into separable and non-separable transform components, allowing selective application based on block characteristics. The transform kernel is segmented into different types (separable vs. non-separable) that can be chosen according to the specific encoding scenario, thus improving efficiency without universally increasing complexity.
Solution Approach 2:
The patent introduces dynamic selection of transform kernels based on encoding parameters and block characteristics. The transform type is not fixed but adaptively chosen during encoding, allowing the system to switch between simple separable transforms and more complex non-separable transforms only when beneficial, thus balancing efficiency improvement with complexity management.
2Loss of substance
If non-separable transform kernel is used to improve transform performance, then compression ratio is improved, but signaling overhead increases
Solution Approach 1:
The patent applies non-separable transform only partially - specifically for certain block types and sizes where it provides benefit, rather than universally. This selective application means signaling overhead is incurred only when needed, not for every transform operation, thus improving compression ratio without proportionally increasing signaling overhead.
Solution Approach 2:
The patent changes the parameter of transform kernel type based on encoding conditions. By varying the transform parameter (separable vs. non-separable) according to block characteristics and encoding mode, the system achieves better compression when using non-separable transforms while minimizing signaling overhead by using them only when appropriate.
Data Source
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AI summary
An image decoding method and device, according to the present disclosure, derive transform coefficients of the current block from a bitstream, determine a non-separable primary transform (NSPT) set for the current block, determine an NSPT kernel of the current block on the basis of the NSPT set and a transform index, perform NSPT on the transform coefficients of the current block on the basis of the NSPT kernel so as to derive residual samples, and can restore the current block on the basis of the residual samples. The NSPT can be applied on the basis that the size of the current block belongs to a group of one or more block sizes to which the NSPT can be applied.