StructCore: Structure-Aware Image-Level Scoring for Training-Free Unsupervised Anomaly Detection

Fuente: arXiv
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Main Authors: Chae, Joongwon, Luo, Lihui, Liu, Yang, Wang, Runming, Yu, Dongmei, Liang, Zeming, Yuan, Xi, Zhang, Dayan, Chen, Zhenglin, Qin, Peiwu, Chae, Ilmoon
Format: Preprint
Published: 2026
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author Chae, Joongwon
Luo, Lihui
Liu, Yang
Wang, Runming
Yu, Dongmei
Liang, Zeming
Yuan, Xi
Zhang, Dayan
Chen, Zhenglin
Qin, Peiwu
Chae, Ilmoon
author_facet Chae, Joongwon
Luo, Lihui
Liu, Yang
Wang, Runming
Yu, Dongmei
Liang, Zeming
Yuan, Xi
Zhang, Dayan
Chen, Zhenglin
Qin, Peiwu
Chae, Ilmoon
contents Max pooling is the de facto standard for converting anomaly score maps into image-level decisions in memory-bank-based unsupervised anomaly detection (UAD). However, because it relies on a single extreme response, it discards most information about how anomaly evidence is distributed and structured across the image, often causing normal and anomalous scores to overlap. We propose StructCore, a training-free, structure-aware image-level scoring method that goes beyond max pooling. Given an anomaly score map, StructCore computes a low-dimensional structural descriptor phi(S) that captures distributional and spatial characteristics, and refines image-level scoring via a diagonal Mahalanobis calibration estimated from train-good samples, without modifying pixel-level localization. StructCore achieves image-level AUROC scores of 99.6% on MVTec AD and 98.4% on VisA, demonstrating robust image-level anomaly detection by exploiting structural signatures missed by max pooling.
format Preprint
id arxiv_https___arxiv_org_abs_2602_17048
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle StructCore: Structure-Aware Image-Level Scoring for Training-Free Unsupervised Anomaly Detection
Chae, Joongwon
Luo, Lihui
Liu, Yang
Wang, Runming
Yu, Dongmei
Liang, Zeming
Yuan, Xi
Zhang, Dayan
Chen, Zhenglin
Qin, Peiwu
Chae, Ilmoon
Computer Vision and Pattern Recognition
Max pooling is the de facto standard for converting anomaly score maps into image-level decisions in memory-bank-based unsupervised anomaly detection (UAD). However, because it relies on a single extreme response, it discards most information about how anomaly evidence is distributed and structured across the image, often causing normal and anomalous scores to overlap. We propose StructCore, a training-free, structure-aware image-level scoring method that goes beyond max pooling. Given an anomaly score map, StructCore computes a low-dimensional structural descriptor phi(S) that captures distributional and spatial characteristics, and refines image-level scoring via a diagonal Mahalanobis calibration estimated from train-good samples, without modifying pixel-level localization. StructCore achieves image-level AUROC scores of 99.6% on MVTec AD and 98.4% on VisA, demonstrating robust image-level anomaly detection by exploiting structural signatures missed by max pooling.
title StructCore: Structure-Aware Image-Level Scoring for Training-Free Unsupervised Anomaly Detection
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2602.17048