Adaptive Pixel Classification for Video In-Loop Filtering

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Solution Overview

Problem

Conventional video coding standards, such as HEVC, face limitations in accurately correcting errors in reconstructed images due to the restricted nature of edge and band offsets, which are insufficient for handling the diverse features of modern images.

Innovation Solution

An adaptive pixel classification method is introduced for in-loop filtering, where reconstructed samples are classified using either absolute or relative standards, and an offset value is added based on the classification results, allowing for more precise error correction and feature-specific offset application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional edge offset and band offset are used for sample adaptive offset, then the filtering process is simple, but the error correction capability is limited due to restricted classification standards

Engineering Contradiction:
Improveerror correction precisionVSAvoidfiltering process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The reconstructed sample is divided into multiple categories using multiple classification standards (absolute classification and relative classification). Each category receives a specific offset value tailored to its characteristics, enabling precise error correction for different image features such as edges, bands, and flat regions without overwhelming complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different offset values are applied to different categories of reconstructed samples based on their local characteristics. The absolute classification standard identifies samples by brightness value bands, while the relative classification standard identifies samples by edge and gradient features, allowing each local region to receive appropriate correction

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If multiple classification standards are applied for adaptive pixel classification, then the adaptability to diverse image features is improved, but the computational complexity increases

Engineering Contradiction:
Improveadaptability to image featuresVSAvoidclassification process complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The classification process is segmented into two independent standards: absolute classification (based on brightness value bands) and relative classification (based on edge and gradient information). This segmentation allows the system to handle diverse image features adaptively while maintaining manageable computational complexity through modular processing

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The filtering system dynamically selects and applies appropriate classification standards based on the characteristics of each reconstructed sample. The dual classification approach enables the system to adapt to varying image features (edges, bands, flat regions) while the offset values are dynamically adjusted according to classification results

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS11991366B2In-loop filtering method according to adaptive pixel classification standard
Publication Date: 2024.05.21 INDUSTRY UNIVERSITY COOPERATION FOUNDATION HANYANG UNIVERSITY
  • US11991366B2 patent drawing
  • US11991366B2 patent drawing
  • US11991366B2 patent drawing

AI summary

The in-loop filtering method performed by a video decoding apparatus includes: classifying reconstructed samples according to an absolute classification standard or relative classification standard; acquiring offset data on the basis of results of classifying the reconstructed samples; adding an offset value to the reconstructed samples by referencing the acquired offset data; and outputting the offset value-added reconstructed samples. Accordingly, W errors in the reconstructed image can be corrected.