A Feature Shuffling and Restoration Strategy for Universal Unsupervised Anomaly Detection

TL;DR

This paper proposes a universal unsupervised anomaly detection framework called FSR that uses feature shuffling and restoration to improve detection across diverse scenarios by focusing on global context and reducing shortcut issues.

Contribution

The paper introduces the FSR framework, a novel approach employing feature shuffling and restoration with multi-scale features to enhance universal anomaly detection performance.

Findings

FSR outperforms existing methods across various settings.

The shuffling rate effectively regulates task complexity.

Theoretical analysis supports FSR's effectiveness from structural and information perspectives.

Abstract

Unsupervised anomaly detection is vital in industrial fields, with reconstruction-based methods favored for their simplicity and effectiveness. However, reconstruction methods often encounter an identical shortcut issue, where both normal and anomalous regions can be well reconstructed and fail to identify outliers. The severity of this problem increases with the complexity of the normal data distribution. Consequently, existing methods may exhibit excellent detection performance in a specific scenario, but their performance sharply declines when transferred to another scenario. This paper focuses on establishing a universal model applicable to anomaly detection tasks across different settings, termed as universal anomaly detection. In this work, we introduce a novel, straightforward yet efficient framework for universal anomaly detection: \uline{F}eature \uline{S}huffling and \uline{R}estoration (FSR), which can alleviate the identical shortcut issue across different settings. First and foremost, FSR employs multi-scale features with rich semantic information as reconstruction targets, rather than raw image pixels. Subsequently, these multi-scale features are partitioned into non-overlapping feature blocks, which are randomly shuffled and then restored to their original state using a restoration network. This simple paradigm encourages the model to focus more on global contextual information. Additionally, we introduce a novel concept, the shuffling rate, to regulate the complexity of the FSR task, thereby alleviating the identical shortcut across different settings. Furthermore, we provide theoretical explanations for the effectiveness of FSR framework from two perspectives: network structure and mutual information. Extensive experimental results validate the superiority and efficiency of the FSR framework across different settings.Code is available at https://github.com/luow23/FSR.