Temporal Chroma Loop Filtering Using Motion-Compensated Reference Samples
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Solution Overview
Problem
Existing video coding technologies face challenges in effectively addressing spatial and temporal redundancies in video data, leading to suboptimal image quality and coding efficiency, particularly in the filtering of chroma samples using conventional loop filters.
Innovation Solution
The implementation of adaptive loop filters, including temporal chroma adaptive loop filters, which apply filtering offsets based on motion vector information to enhance chroma samples in the current picture, utilizing filter coefficients determined by local image characteristics and motion vectors from reference pictures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional loop filters are used for chroma samples, then device complexity is reduced, but image quality and coding efficiency deteriorate
Solution Approach 1:
The patent implements dynamic adaptation of filter coefficients based on motion vector information and local image characteristics. The filter transitions from a static conventional approach to a dynamic system that adjusts its behavior according to motion activity and chroma-luma correlation, resolving the contradiction by making the filter adaptive rather than fixed
Solution Approach 2:
The patent applies different filtering strategies to different regions based on local characteristics such as motion vector magnitude and chroma-luma correlation strength. Areas with high motion or strong correlation receive adaptive filtering while other areas use conventional filtering, optimizing image quality without uniformly increasing complexity across the entire image
2Productivity
If conventional loop filters are used for chroma samples, then processing speed is maintained, but coding efficiency deteriorates
Solution Approach 1:
The patent changes key parameters including motion vector information and chroma-luma correlation metrics to dynamically adjust filter coefficients. This allows the system to optimize coding efficiency by adapting to local characteristics while maintaining processing speed through efficient parameter calculation and filter application
3Manufacturing precision
If adaptive loop filters with motion vector information are applied, then chroma sample filtering quality is improved, but device complexity increases
Solution Approach 1:
The patent applies adaptive filtering selectively based on local chroma-luma correlation strength and motion characteristics. Only regions exhibiting strong correlation and significant motion receive the computationally intensive adaptive filtering, while other regions use conventional filtering, thus improving chroma quality where needed without uniformly increasing device complexity
Solution Approach 2:
The patent implements partial adaptive filtering by applying the complex motion-compensated filter only to specific chroma samples that benefit most from it, rather than to all chroma samples. This partial application improves quality for critical regions while limiting the increase in overall device complexity
Data Source
AI summary
Some aspects of the disclosure provide a method of video decoding. For example, a bitstream that comprises coded information of one or more pictures is received. Motion vector information associated with a current chroma sample of a current block in a current picture is derived. The motion vector information points to a reference sample in a reference picture of the current picture. An adaptive loop filter of a temporal domain is applied on the reference sample and one or more neighboring samples of the reference sample in the reference picture to generate a filtering offset for the current chroma sample in the current picture. A filtered value of the current chroma sample is generated according to the filtering offset.