Filter-Unit In-Loop Filtering for Video Artifact Reduction

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Solution Overview

Problem

Conventional video coding systems lack adaptivity in in-loop filtering, leading to visual artifacts due to intensity shifts, and existing methods are inefficient in conveying filter information to adapt to local picture characteristics, requiring increased bandwidth.

Innovation Solution

Implementing filter-unit based in-loop filtering that partitions video data into smaller processing units (FUs) with adaptive filter parameters and syntax designs that allow for efficient and flexible conveyance of filter information, including FU size determination and merge flags, to apply filters dynamically based on local characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If picture-level in-loop filtering is applied with shared filter parameters, then device complexity is reduced and ease of operation is improved, but adaptability to local picture characteristics deteriorates

Engineering Contradiction:

Improvefiltering system complexityVSAvoidadaptability to local picture characteristics

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The picture is divided into multiple filter units (FUs) of a specific size, where each FU can have independent filter parameters. This segmentation allows local adaptivity while keeping each unit's processing relatively simple, resolving the contradiction between complexity and adaptability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different filter parameters are applied to different filter units based on local picture characteristics. Each FU can have its own filter index and parameters, enabling local quality adaptation without requiring complex global optimization.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If in-loop filtering with local adaptivity is implemented, then adaptability to local picture characteristics is improved, but bandwidth requirements increase due to additional filter information

Engineering Contradiction:

Improvelocal adaptivityVSAvoidbandwidth for filter information

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

Adjacent filter units can be merged into larger filter groups that share common filter parameters. This merging reduces the total number of parameters that need to be transmitted, lowering bandwidth requirements while maintaining local adaptivity within each group.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

A set of predefined filter kernels is created that can be universally applied across different filter units. By selecting from this universal set using filter indices, the system achieves local adaptivity without transmitting full filter parameter sets for each FU, thus reducing bandwidth.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If in-loop filtering with local adaptivity is implemented, then video quality is improved by reducing artifacts, but device complexity increases

Engineering Contradiction:

Improvevideo qualityVSAvoidfiltering system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Filter parameters such as filter index, filter strength, and filter type are dynamically changed based on local picture characteristics detected in each filter unit. This allows the system to adapt to local variations in video content, improving quality by reducing artifacts like blocking effects and intensity shifts.

Inventive Principle:

Principle #35Parameter changes

4Adaptability or versatility

If filter parameters are transmitted for each filter unit, then adaptability is improved, but coding efficiency decreases due to increased bitstream size

Engineering Contradiction:

Improvefilter parameter adaptivityVSAvoidcoding efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Filter parameters from one filter unit can be copied to adjacent filter units when they have similar characteristics. This copying approach reduces the number of unique parameters that need to be encoded and transmitted, improving coding efficiency while maintaining adaptivity where needed.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS10567751B2Method of filter-unit based in-loop filtering

Publication Date: 2020.02.18 HFI INNOVATION INC

AI summary

In one embodiment, a method receives a video bitstream corresponding to compressed video, wherein Filter Unit (FU) based in-loop filtering is allowed in a reconstruction loop associated with the compressed video. The method then derives reconstructed video from the video bitstream, wherein the reconstructed video is partitioned into FUs and derives a merge flag from the video bitstream for each of the FUs, wherein the merge flag indicates whether said each of the FUs is merged with a neighboring FU. The method further receives a merge index from the video bitstream if the merge flag indicates that said each of the FUs is merged, and receives the filter parameters from the video bitstream if the merge flag indicates that said each of the FUs is not merged. Finally, the method applies the in-loop filtering to said each of the FUs using the filter parameters.