Combined Loop Filter for Video Coding
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Solution Overview
Problem
Existing video coding standards face challenges in efficiently combining loop filters, such as bilateral filtering and sample adaptive offset (SAO) filtering, due to issues like over-filtering and difficulty in hardware implementation, which affect compression efficiency and latency.
Innovation Solution
Combining two loop filters, like bilateral filtering and SAO, into a single loop filter stage, where both filters operate in parallel, and feeding both the unfiltered and filtered samples to the parameter estimation module to accurately estimate filter parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple loop filters are applied sequentially to improve compression efficiency, then visual quality is improved, but processing latency and device complexity increase
Solution Approach 1:
The patent combines multiple loop filters (bilateral filter and SAO filter) into a single processing stage where both filters operate in parallel on the same input block, producing combined output that achieves the compression efficiency of sequential filtering without the latency penalty of sequential processing
Solution Approach 2:
The patent segments the filtering process by allowing different filters to operate independently in parallel on different aspects of the same input block, then combines their outputs, enabling simultaneous execution rather than sequential execution
2Manufacturing precision
If multiple loop filters are applied sequentially to improve compression efficiency, then visual quality is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple filter processing paths into a unified hardware structure where bilateral filtering and SAO filtering share common input blocks and operate in the same processing stage, reducing the overall device complexity compared to implementing separate sequential filter stages
3Loss of substance
If loop filters are applied to improve compression efficiency, then bit rate is reduced, but over-filtering occurs degrading visual quality
Solution Approach 1:
The patent uses the output of the bilateral filter as input for SAO parameter estimation, creating a feedback mechanism where the first filter's results inform the configuration of the second filter, allowing the system to adapt and avoid over-filtering while maintaining compression efficiency
Solution Approach 2:
The patent implements dynamic parameter estimation for SAO based on bilateral filter outputs, allowing the filtering strength and characteristics to adapt to local image content, preventing excessive filtering in regions where it would degrade visual quality
Data Source
AI summary
There is provided a method for encoding one or more images. The method comprises filtering, with a first filter, input samples I(x,y) to generate a first filtered output Ifirst(x,y)=I(x,y)+ΔIfirst(x,y). The method comprises estimating parameters for a second filter based at least in part on the first filtered output Ifirst(x,y), the input samples I(x,y), and original samples Iorig(x,y). The method comprises filtering, with the second filter, input samples I(x,y) to generate a second filtered output Isecond(x,y)=I(x,y)+ΔIsecond(x,y), wherein filtering, with the second filter, is based at least in part on the parameters estimated for the second filter. The method comprises generating a combined output ICOMB(x,y)=I(x,y)+ΔIfirst(x,y)+ΔIsecond(x,y).