Deblocking Filter for Sub-Partition Boundaries in Intra Coding
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Solution Overview
Problem
Intra sub-partition coding in video compression leads to discontinuities across sub-partition boundaries, causing undesirable blocking artifacts that are challenging to address with existing deblocking filtering techniques.
Innovation Solution
A deblocking method that modifies up to one sample in each sub-partition when the sub-partition width or height is 4 samples, allowing for efficient filtering of sample values at the boundaries to reduce artifacts, while minimizing computational load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If intra sub-partition coding is applied to improve compression efficiency, then coding efficiency is improved, but blocking artifacts are introduced at sub-partition boundaries
Solution Approach 1:
A deblocking filter is introduced as an intermediary processing step between the intra sub-partition coding and the final output. The filter processes sample values at sub-partition boundaries to reduce blocking artifacts while preserving the compression efficiency benefits of ISP coding. The filter operates on reconstructed sample values and modifies them based on boundary characteristics.
Solution Approach 2:
The patent applies different filtering strengths and parameters at different boundary locations. Boundary strength values are adjusted based on whether the boundary is strong or weak, and the filter parameters are modified according to the specific sub-partition configuration and boundary characteristics to optimize artifact reduction.
2Object-affected harmful factors
If conventional deblocking filtering is applied to remove blocking artifacts, then blocking artifacts are reduced, but computational complexity increases
Solution Approach 1:
Instead of applying full-strength deblocking filtering across the entire image, the patent applies filtering only at sub-partition boundaries where blocking artifacts occur. The filter processes only the necessary sample values at boundaries, not the entire block, thereby reducing computational complexity while maintaining effective artifact reduction.
Solution Approach 2:
The deblocking filter applies different processing strength and parameters to different boundary locations. Strong boundaries receive stronger filtering than weak boundaries, and the filter adapts its parameters locally based on boundary characteristics, optimizing computational efficiency by avoiding unnecessary processing at low-risk locations.
Data Source
AI summary
A deblocking method is provided for deblocking a sub-partition boundary within a coding block during image encoding and/or image decoding process. The coding block is coded in an intra prediction mode and the coding block is partitioned into sub-partitions comprising a first sub-partition and a second sub-partition that is adjacent to the first sub-partition. The method comprises: determining a maximum filter length to be 1 for a first/second sub-partition when a width of the first or second sub-partition is 4 samples, or when a height of the first or second sub-partition is 4 samples; modifying a value of up to one sample of the first or second sub-partition, wherein the value of the up to one sample is obtained from a row or a column of the first or second sub-partition that is perpendicular to and adjacent to the sub-partitions boundary between the first sub-partition and the second sub-partition.