Affine Motion Compensation With Local Illumination Correction
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Solution Overview
Problem
Existing video compression technologies, such as those in the Joint Exploration Model (JEM), do not fully leverage the potential of affine motion models and block-based local illumination compensation (LIC) to correct for illumination variations, leading to suboptimal compression efficiency when affine motion prediction is used.
Innovation Solution
Implementing a method to activate the LIC tool for inter-mode coded CUs using affine motion prediction, deriving LIC parameters based on motion vectors, and incorporating them into the bitstream without additional overhead, thereby improving compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If affine motion model is used for video compression, then motion prediction accuracy is improved, but compression efficiency deteriorates due to inability to correct illumination variations
Solution Approach 1:
The patent combines affine motion compensation with block-based local illumination compensation (LIC) by integrating LIC parameter derivation into the affine motion prediction framework. The LIC tool is activated for inter-mode coded CUs using affine motion prediction, merging two previously separate processes into a unified approach that corrects both motion and illumination variations simultaneously.
Solution Approach 2:
The patent derives LIC parameters (a and b) based on motion vectors from the affine motion model. By changing how LIC parameters are obtained - using affine motion vectors instead of traditional methods - the system adapts illumination compensation to work seamlessly with affine motion prediction, improving overall compression efficiency.
2Measurement precision
If LIC parameters are derived based on motion vectors, then illumination compensation accuracy is improved, but computational complexity increases
Solution Approach 1:
The system uses the motion vectors already computed for affine motion prediction to derive LIC parameters. Instead of requiring separate, complex illumination analysis, the method leverages existing motion compensation data structures and computations to obtain LIC parameters, making the additional complexity minimal while maintaining high accuracy.
3Productivity
If LIC tool is activated for affine motion prediction, then rate-distortion performance is improved, but bitstream overhead increases
Solution Approach 1:
The patent makes the LIC tool universally applicable to inter-mode coded CUs using affine motion prediction. By designing the LIC parameter derivation to work within the existing affine motion framework using the same motion vectors and data structures, the system achieves multi-functionality where a single set of computations serves both motion compensation and illumination compensation purposes.
Data Source
AI summary
A video codec can involve processing video information based on a motion model involving a coding unit including a plurality of sub-blocks, such as an affine motion model, to produce motion compensation information, obtaining a local illumination compensation model, and encoding or decoding the video information based on the motion compensation information and the local illumination compensation model.