Papers › Fully Convolutional Cross-Scale-Flows for Image-based Defect Detection

Fully Convolutional Cross-Scale-Flows for Image-based Defect Detection

6 Oct 2021arXiv:2110.02855archive 2025-07-28

Marco Rudolph, Tom Wehrbein, Bodo Rosenhahn, Bastian Wandt

In industrial manufacturing processes, errors frequently occur at unpredictable times and in unknown manifestations. We tackle the problem of automatic defect detection without requiring any image samples of defective parts. Recent works model the distribution of defect-free image data, using either strong statistical priors or overly simplified data representations. In contrast, our approach handles fine-grained representations incorporating the global and local image context while flexibly estimating the density. To this end, we propose a novel fully convolutional cross-scale normalizing flow (CS-Flow) that jointly processes multiple feature maps of different scales. Using normalizing flows to assign meaningful likelihoods to input samples allows for efficient defect detection on image-level. Moreover, due to the preserved spatial arrangement the latent space of the normalizing flow is interpretable which enables to localize defective regions in the image. Our work sets a new state-of-the-art in image-level defect detection on the benchmark datasets Magnetic Tile Defects and MVTec AD showing a 100% AUROC on 4 out of 15 classes.

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Code

marco-rudolph/cs-flow officialmentioned in papermentioned on GitHubpytorch report

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Tasks

Anomaly DetectionDefect DetectionUnsupervised Anomaly Detection

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Anomaly Detection MVTec AD CS-Flow Detection AUROC 98.7 #54 of 148 Archive leaderboard report
Anomaly Detection Surface Defect Saliency of Magnetic Tile CS-Flow (unsupervised) Detection AUROC 99.3 #2 of 4 Archive leaderboard report

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Methods

Normalizing Flows

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