Video Illumination Compensation Using Joint Reference-Block Parameters
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Solution Overview
Problem
Existing video encoding methods using illumination compensation (IC) face limitations when neighboring samples belong to different objects than the current block, leading to suboptimal estimation of IC parameters, particularly in bi-prediction scenarios.
Innovation Solution
Derive IC parameters jointly from sets of reconstructed samples of reference blocks, rather than relying on L-shaped sets of neighboring samples, and apply these parameters to both reference blocks in bi-prediction mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If L-shaped sets of neighboring samples are used to estimate IC parameters, then the estimation process is simple, but the accuracy deteriorates when neighboring samples belong to different objects
Solution Approach 1:
The patent extracts the relevant samples specifically from the reference blocks (first and second motion compensated reference blocks) rather than using the conventional L-shaped neighboring samples. This extraction of relevant data from the correct source (reference blocks belonging to the same object as the current block) resolves the accuracy issue while maintaining a systematic approach to parameter derivation.
Solution Approach 2:
The patent introduces an intermediary process of jointly deriving IC parameters from multiple reference blocks before applying them to the current block. This intermediary step ensures that the parameters are suited for the current block's object characteristics, bridging the gap between reference data and current block prediction.
2Measurement precision
If IC parameters are derived separately for each reference block in bi-prediction, then the derivation process is straightforward, but the overall illumination compensation accuracy deteriorates
Solution Approach 1:
The patent merges the IC parameter derivation process by jointly deriving a single set of IC parameters from both the first and second motion compensated reference blocks. This combined approach ensures consistency and accuracy in bi-prediction scenarios, as the parameters are derived from both reference sources rather than separately, improving overall illumination compensation accuracy.
3Manufacturing precision
If IC parameters are not suited for the current block, then the encoding process is faster, but the video quality deteriorates
Solution Approach 1:
The patent performs preliminary action by deriving IC parameters from reference blocks before the actual encoding of the current block. This advance derivation ensures that accurate, block-suited parameters are ready when needed, improving video quality without significantly impacting encoding time since the parameters are derived from already-available reference block data.
Data Source
AI summary
Methods and apparatuses for video coding and decoding are provided. The method of video encoding includes determining a set of parameters for illumination compensation associated with a first motion compensated reference block of a block in a picture of a video based on a function of a set of samples of the first motion compensated reference block and a set of samples of a second motion compensated reference block of the block, processing a prediction of the block based on the set of parameters, the prediction being associated with the first motion compensated reference block and encoding the block based on the processed prediction. A bitstream formatted to include encoded data, a computer-readable storage medium and a computer program product are also described.