Intra-Mode Reduced Secondary Transforms for Efficient Video Coding
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Solution Overview
Problem
The increasing demand for high-resolution and high-quality images/videos, including immersive media, necessitates a highly 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 optimizes the transformation kernel matrix and array of transform coefficients based on intra prediction mode, enhancing coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution and high-quality images/videos are transmitted or stored using conventional methods, then image quality is maintained, but transmission cost and storage cost increase
Solution Approach 1:
The patent applies parameter changes by modifying the transform coefficients through a secondary transform process. The transform coefficients are adjusted based on prediction mode information, allowing for more efficient representation of image data. This changes the parameters of the coefficient representation to achieve better compression while maintaining quality.
Solution Approach 2:
The patent implements dynamics by adaptively selecting different secondary transform kernels based on the prediction mode. The transform process is not static but dynamically adjusts its parameters according to the specific characteristics of each block, optimizing compression efficiency for different types of content.
2Productivity
If conventional transform methods are used for image coding, then implementation is simple, but coding efficiency is insufficient for high-resolution images
Solution Approach 1:
The patent applies segmentation by dividing the transform process into multiple stages: a primary transform followed by a secondary transform. This segmented approach allows each transform stage to handle specific aspects of the data, improving overall efficiency while keeping each individual stage relatively simple.
Solution Approach 2:
The patent implements preliminary action by performing a primary transform first to generate initial transform coefficients, then using these coefficients as input for the secondary transform. This preliminary processing prepares the data in a way that makes the subsequent secondary transform more effective.
3Productivity
If transform coefficients are not optimized according to prediction mode, then processing is faster, but coding efficiency is reduced
Solution Approach 1:
The patent changes parameters by selecting different secondary transform kernels based on the prediction mode. This parameter adaptation allows the transform to be optimized for the specific characteristics of each block, improving coding efficiency without requiring complete reprocessing.
Solution Approach 2:
The patent applies local quality by using different transform kernels for different regions (blocks) based on their prediction modes. Each block receives a transform optimized for its local characteristics, improving overall efficiency while keeping the processing approach localized and manageable.
Data Source
AI summary
A video transform method includes: receiving a quantized transform coefficient for a target block and a transform index for a non-separated secondary transform; inverse-quantizing the quantized transform coefficient; deriving an input transform coefficient size indicating the length of the inverse-quantized transform coefficient to which the non-separated secondary transform has been applied, an output transform coefficient size indicating the length of a modified transform coefficient to which the non-separated secondary transform has been applied, and a transform set mapped to the intra mode of the target block, when the transform index does not indicate that the non-separated secondary transform is not performed; and deriving the modified transform coefficient on the basis of a matrix operation on a transform kernel matrix in the transform set indicated by the transform index, and a transform coefficient list corresponding to the input transform coefficient size.