CNC: Cross-modal Normality Constraint for Unsupervised Multi-class Anomaly Detection

Fuente: arXiv
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Main Authors: Wang, Xiaolei, Wang, Xiaoyang, Bai, Huihui, Lim, Eng Gee, Xiao, Jimin
Format: Preprint
Published: 2024
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author Wang, Xiaolei
Wang, Xiaoyang
Bai, Huihui
Lim, Eng Gee
Xiao, Jimin
author_facet Wang, Xiaolei
Wang, Xiaoyang
Bai, Huihui
Lim, Eng Gee
Xiao, Jimin
contents Existing unsupervised distillation-based methods rely on the differences between encoded and decoded features to locate abnormal regions in test images. However, the decoder trained only on normal samples still reconstructs abnormal patch features well, degrading performance. This issue is particularly pronounced in unsupervised multi-class anomaly detection tasks. We attribute this behavior to over-generalization(OG) of decoder: the significantly increasing diversity of patch patterns in multi-class training enhances the model generalization on normal patches, but also inadvertently broadens its generalization to abnormal patches. To mitigate OG, we propose a novel approach that leverages class-agnostic learnable prompts to capture common textual normality across various visual patterns, and then apply them to guide the decoded features towards a normal textual representation, suppressing over-generalization of the decoder on abnormal patterns. To further improve performance, we also introduce a gated mixture-of-experts module to specialize in handling diverse patch patterns and reduce mutual interference between them in multi-class training. Our method achieves competitive performance on the MVTec AD and VisA datasets, demonstrating its effectiveness.
format Preprint
id arxiv_https___arxiv_org_abs_2501_00346
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle CNC: Cross-modal Normality Constraint for Unsupervised Multi-class Anomaly Detection
Wang, Xiaolei
Wang, Xiaoyang
Bai, Huihui
Lim, Eng Gee
Xiao, Jimin
Computer Vision and Pattern Recognition
Artificial Intelligence
Machine Learning
Existing unsupervised distillation-based methods rely on the differences between encoded and decoded features to locate abnormal regions in test images. However, the decoder trained only on normal samples still reconstructs abnormal patch features well, degrading performance. This issue is particularly pronounced in unsupervised multi-class anomaly detection tasks. We attribute this behavior to over-generalization(OG) of decoder: the significantly increasing diversity of patch patterns in multi-class training enhances the model generalization on normal patches, but also inadvertently broadens its generalization to abnormal patches. To mitigate OG, we propose a novel approach that leverages class-agnostic learnable prompts to capture common textual normality across various visual patterns, and then apply them to guide the decoded features towards a normal textual representation, suppressing over-generalization of the decoder on abnormal patterns. To further improve performance, we also introduce a gated mixture-of-experts module to specialize in handling diverse patch patterns and reduce mutual interference between them in multi-class training. Our method achieves competitive performance on the MVTec AD and VisA datasets, demonstrating its effectiveness.
title CNC: Cross-modal Normality Constraint for Unsupervised Multi-class Anomaly Detection
topic Computer Vision and Pattern Recognition
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2501.00346