Multi-Reference Intra Prediction Filtering to Reduce Blocking Artifacts
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Solution Overview
Problem
Existing video coding methods suffer from blocking artifacts due to the limitations of in-loop filtering, particularly in the case of intra prediction from multiple reference blocks, which are not adequately addressed by current deblocking filters in standards like H.265.
Innovation Solution
A method and device for decoding and encoding blocks that involve filtering multiple reference blocks with a deblocking filter along their edges before intra prediction, enhancing the filtering process to reduce internal discontinuities and improve coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deblocking filter is applied only at block boundaries (external frontiers), then the filtering process is simple and fast, but internal discontinuities and blocking artifacts remain within blocks predicted from multiple reference blocks
Solution Approach 1:
The patent segments the filtering process into two stages: first applying the deblocking filter at block boundaries (external frontiers), then applying a second filtering pass at internal edges within blocks. This segmentation allows the system to address both boundary artifacts and internal discontinuities separately, improving overall filtering effectiveness without overwhelming complexity in a single filter design.
Solution Approach 2:
The patent applies the deblocking filter at block boundaries before performing intra prediction from multiple reference blocks. This preliminary filtering action removes boundary artifacts before they can propagate into the prediction process, reducing the burden on subsequent internal filtering and improving overall coding efficiency.
2Measurement precision
If multiple reference blocks are used for intra prediction, then prediction accuracy improves, but blocking artifacts increase due to discontinuities at block boundaries
Solution Approach 1:
The patent applies the deblocking filter at block boundaries before using multiple reference blocks for prediction. This preliminary anti-action counteracts the harmful discontinuities at boundaries before they can propagate into the prediction process, allowing the system to benefit from multi-reference prediction accuracy without suffering from increased blocking artifacts.
Solution Approach 2:
The filtering operation is performed in advance, before the intra prediction step, so that the reference blocks used for prediction already have reduced boundary artifacts. This preliminary action ensures that the prediction process works with cleaner reference data, improving accuracy while reducing artifacts.
3Productivity
If in-loop filtering is enhanced to reduce blocking artifacts, then coding efficiency improves, but processing time and computational complexity increase
Solution Approach 1:
The patent segments the filtering operations into distinct passes: one for block boundaries and one for internal edges. This segmentation allows the system to perform filtering in organized stages rather than simultaneously processing all edges, improving computational efficiency and reducing overall processing time while maintaining comprehensive artifact reduction.
Solution Approach 2:
By performing boundary filtering before prediction and using the cleaned reference blocks for subsequent processing, the patent reduces the need for more intensive filtering operations later in the pipeline. This preliminary action lightens the overall computational burden while still achieving comprehensive artifact reduction.
Data Source
AI summary
Edges of the plurality of reference blocks are adjacent to a current block of a picture. A single transform is applied to samples of each reference block. A single transform is applied to samples of the current block. A decoding method includes decoding a plurality of reference blocks, obtaining a plurality of filtered reference blocks by filtering with a deblocking filter along the edges of the plurality of decoded reference blocks, and decoding the current block by intra prediction from the plurality of filtered reference blocks. An encoding method includes encoding and reconstructing a plurality of reference blocks, obtaining a plurality of filtered reference blocks by filtering with a deblocking filter along the edges of the plurality of reconstructed reference blocks, and encoding the current block by intra prediction from the plurality of filtered reference blocks.