Secondary Transform Coefficient Layout for Higher Image Coding Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increasing demand for high-resolution and high-quality images/videos, particularly in immersive media formats like VR and AR, necessitates a more efficient image/video compression technique to reduce transmission and storage costs.
Innovation Solution
An image coding method and apparatus utilizing a reduced secondary transform (RST) that adjusts the array of transform coefficients based on intra prediction mode, employing an inverse RST to derive modified transform coefficients in a two-dimensional array from a one-dimensional array, enhancing coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional transform methods are used for high-resolution images/videos, then image quality is maintained, but transmission cost and storage cost increase
Solution Approach 1:
The transform process is divided into two stages: primary transform and secondary transform. The primary transform processes the residual signal first, and the secondary transform further processes the primary transform coefficients. This segmentation allows for more efficient compression while maintaining image quality, reducing transmission and storage costs.
Solution Approach 2:
The patent introduces a secondary transform that operates on the one-dimensional array of primary transform coefficients to produce a two-dimensional array of transform coefficients. This dimensional transformation enables more effective energy compaction and compression efficiency improvement without compromising image quality.
2Productivity
If transform efficiency is increased through secondary transform, then coding efficiency improves, but device complexity increases
Solution Approach 1:
The secondary transform is applied selectively rather than universally. The transform coefficients are processed in a one-dimensional array format first, and the secondary transform is applied to enhance compression efficiency where needed. This partial application approach improves coding efficiency while controlling the increase in device complexity.
Data Source
AI summary
An image decoding method according to the present document comprises the steps of: deriving transform coefficients through inverse quantization on the basis of quantized transform coefficients for a target block; deriving modified transform coefficients on the basis of an inverse reduced secondary transform (RST) for the transform coefficients; and generating, on the basis of an inverse primary transform for the modified transform coefficients, a restoration picture based on residual samples for the target block, wherein the modified transform coefficients derived according to the inverse RST are two-dimensionally arranged according to the order of a row priority direction or a column priority direction according to an intra prediction mode to be applied to the target block.