Weighted Inter Prediction for Video Coding Efficiency
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Solution Overview
Problem
The increasing demand for high-resolution, high-quality images such as HD and UHD images leads to a significant increase in the amount of information to be transmitted and stored, resulting in higher transmission and storage costs, necessitating a highly efficient image compression technique.
Innovation Solution
A video coding method and device that applies weights to L0 motion information and L1 motion information for a current block, deriving these motion informations and weights to perform a weighted-sum prediction, thereby improving prediction accuracy and reducing the amount of additional information needed for coding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inter prediction is used without weights, then device complexity is reduced, but prediction accuracy deteriorates
Solution Approach 1:
The patent applies parameter changes by introducing weight parameters (w0 and w1) to modify the prediction process. Instead of using simple average or single motion vector prediction, the patent changes the prediction parameter space by incorporating weighted combinations of multiple motion information sources (L0 and L1 motion vectors, multiple reference pictures), thereby improving prediction accuracy while managing complexity through systematic parameter optimization.
2Reliability
If high-resolution images are transmitted without efficient compression, then image quality is maintained, but transmission cost increases
Solution Approach 1:
The patent improves coding efficiency by changing parameters related to motion information representation. By using weighted prediction with optimized weight parameters and deriving motion information from multiple sources (L0/L1 lists, multiple reference pictures), the patent achieves better prediction accuracy, which reduces the residual signal energy and consequently reduces the bits needed for transmission, thereby lowering transmission cost while maintaining image quality.
3Measurement precision
If additional information for L0 and L1 motion information and weights is transmitted, then prediction accuracy is improved, but amount of information to be transmitted increases
Solution Approach 1:
The patent applies partial action by selectively transmitting weight information only when beneficial. The syntax structure allows the encoder to signal weight parameters (w0, w1) conditionally based on prediction mode and block characteristics. This partial transmission approach provides prediction accuracy improvement where needed while avoiding unnecessary information transmission, thereby balancing prediction accuracy with information quantity.
Solution Approach 2:
The patent optimizes the quantity of information by changing how motion information parameters are represented and transmitted. Instead of transmitting full precision motion vectors and weights for all blocks, the patent uses parameter optimization techniques including deriving weights from existing motion information, using differential coding for weight parameters, and selectively applying weighted prediction only to blocks where it provides significant improvement, thereby reducing overall information quantity while maintaining prediction accuracy.
Data Source
AI summary
A method for decoding an image by a decoding apparatus according to the present invention comprises the steps of: deriving first motion information of a current block in a first direction and second motion information of the current block in a second direction; deriving a first reference sample on the basis of the first motion information; deriving a second reference sample on the basis of the second motion information; deriving a first weight for the first reference sample and a second weight for the second reference sample; and generating a prediction sample of the current block by performing a weighted summation of the first and second reference samples on the basis of the first and second weights, wherein the first motion information comprises a first reference picture index and a first MV and the second motion information comprises a second reference picture index and a second MV.