Adaptive Loop Filter Level Signaling for Video Coding Efficiency
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Solution Overview
Problem
The increasing demand for high-resolution and high-quality images leads to higher information sizes, resulting in increased transmission and storage costs due to the inefficiencies of conventional wired/wireless broadband and storage media.
Innovation Solution
An image decoding and encoding method that includes signaling information about an adaptive loop filter (ALF) applied at a picture or slice level, allowing for the derivation of filter coefficients and generating modified reconstructed samples based on residual information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adaptive loop filter is applied at picture level, then filtering is performed on entire picture, but processing time and complexity increase
Solution Approach 1:
The patent divides the picture into slices and applies adaptive loop filter at the slice level rather than the entire picture level. This segmentation allows the filtering process to be applied only to relevant portions of the image, reducing overall processing time while maintaining quality where needed.
Solution Approach 2:
The patent introduces dynamic control of ALF application through flags that can be set at picture header or slice header level. This allows the system to adaptively decide whether to apply filtering based on content characteristics, switching between full-picture and selective slice-level filtering as needed.
2Device complexity
If adaptive loop filter is applied at slice level, then processing complexity is reduced, but filtering consistency across picture boundaries may be compromised
Solution Approach 1:
The patent implements feedback mechanisms where filtering parameters and decisions at the slice level are informed by picture-level context. The flag indicating whether ALF is applied at picture or slice level provides feedback that guides the filtering process, ensuring consistency across boundaries while maintaining slice-level flexibility.
Solution Approach 2:
The patent creates a multi-functional filtering system where the same adaptive loop filter can operate at both picture level and slice level depending on configuration. This universality allows the filter to maintain consistency across boundaries when needed while providing slice-level processing when complexity reduction is prioritized.
3Productivity
If filter coefficients are derived from residual information, then compression efficiency improves, but decoding processing steps increase
Solution Approach 1:
The patent performs preliminary derivation of filter coefficients from residual information during the encoding process. By pre-computing these coefficients and signaling them appropriately, the decoding process receives ready-to-use parameters rather than requiring complex real-time computation, thus improving compression efficiency without significantly increasing decoding complexity.
Data Source
AI summary
Proposed in an image decoding method according to the present disclosure is indication information regarding whether an adaptive loop filter (ALF) procedure to be applied to a current block is applied at a picture level or at a slice level.