CAINNFlow: Convolutional block Attention modules and Invertible Neural Networks Flow for anomaly detection and localization tasks

TL;DR

CAINNFlow introduces a novel invertible neural network architecture with convolutional block attention modules to improve anomaly detection and localization by preserving spatial structure information, achieving high accuracy and efficiency.

Contribution

The paper proposes a new NF-based model with embedded CBAM and convolutional layers to retain spatial information, enhancing anomaly detection performance.

Findings

Achieves 98.64% pixel-level AUC on MVTec AD dataset.

Outperforms existing methods in accuracy and inference speed.

Effectively retains spatial structure information in anomaly detection.

Abstract

Detection of object anomalies is crucial in industrial processes, but unsupervised anomaly detection and localization is particularly important due to the difficulty of obtaining a large number of defective samples and the unpredictable types of anomalies in real life. Among the existing unsupervised anomaly detection and localization methods, the NF-based scheme has achieved better results. However, the two subnets (complex functions) $s_{i}(u_{i})$ and $t_{i}(u_{i})$ in NF are usually multilayer perceptrons, which need to squeeze the input visual features from 2D flattening to 1D, destroying the spatial location relationship in the feature map and losing the spatial structure information. In order to retain and effectively extract spatial structure information, we design in this study a complex function model with alternating CBAM embedded in a stacked $3\times3$ full convolution, which is able to retain and effectively extract spatial structure information in the normalized flow model. Extensive experimental results on the MVTec AD dataset show that CAINNFlow achieves advanced levels of accuracy and inference efficiency based on CNN and Transformer backbone networks as feature extractors, and CAINNFlow achieves a pixel-level AUC of $98.64\%$ for anomaly detection in MVTec AD.