Joint Chroma Frame Filtering With Weighted Cross-Component Refinement
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Solution Overview
Problem
Existing video coding systems face challenges in efficiently compressing and transmitting digital video signals, particularly in handling chroma components, leading to suboptimal image quality and increased bandwidth requirements.
Innovation Solution
Applying a cross-component adaptive loop filter (CCALF) to a subset of components in video encoding and decoding, deriving refinement signals to modify other components, and using weighted versions of these signals to enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a filter is applied to all chroma components, then image quality is improved, but computational complexity and processing time increase
Solution Approach 1:
The patent applies filtering selectively to specific chroma components (Cb or Cr) based on their individual quality requirements, rather than uniformly filtering all chroma components. The filter is applied to the chroma component that benefits most from filtering, while the other component uses refinement signals derived from the filtered component, thus reducing overall computational complexity while maintaining image quality.
Solution Approach 2:
The patent divides the chroma filtering process into separate stages for different chroma components. Instead of applying a single filter to both Cb and Cr components simultaneously, the filtering is segmented into: (1) applying filter to one dominant chroma component, (2) deriving refinement signals from that filtered component, and (3) applying weighted refinement signals to the other chroma component. This segmentation reduces computational burden.
2Measurement precision
If separate filters are applied to both chroma components, then image quality is improved, but bandwidth requirements increase
Solution Approach 1:
The patent merges the filtering operations for both chroma components by using a single filter applied to one dominant component, then reusing the resulting refinement signals (with different weighting factors) for the other chroma component. This combining approach reduces the total number of filter operations and associated bandwidth requirements while maintaining quality through the joint refinement process.
3Measurement precision
If iterative joint chroma CCALF processing is applied, then image quality is improved, but processing time increases
Solution Approach 1:
The patent performs preliminary filtering on the dominant chroma component first, deriving refinement signals that are then reused for the other chroma component. This preliminary action on one component prepares refinement signals that can be efficiently applied to the other component with simple weighting operations, reducing overall processing time compared to independent filtering of both components.
Data Source
AI summary
A filter may be applied to a subset of components associated with a sample in a coding block. The output of the filter may be used to modify values for other component(s). For example, a filter may be applied to a selected (for example, dominant) component(s). The output of the filter may be used to modify a value for one of the other components (for example, non-dominant components). The output of the filter may be used, for example, after a weighting factor is applied to the filter output, to modify a value for another one of the other components. A joint refinement signal may be obtained, for example, as the filtered output signal minus the filter input signal of the selected component(s). A properly weighted version of the joint refinement signal may be applied to modify the other components.