MBMF: Constructing memory banks of multi‐scale features for anomaly detection

Abstract

Abstract In industrial manufacturing, how to accurately classify defective products and locate the location of defects has always been a concern. Previous studies mainly measured similarity based on extracting single‐scale features of samples. However, only using the features of a single scale is hard to represent different sizes and types of anomalies. Therefore, the authors propose a set of memory banks of multi‐scale features (MBMF) to enrich feature representation and detect and locate various anomalies. To extract features of different scales, different aggregation functions are designed to produce the feature maps at different granularity. Based on the multi‐scale features of normal samples, the MBMF are constructed. Meanwhile, to better adapt to the feature distribution of the training samples, the authors proposed a new iterative updating method for the memory banks. Testing on the widely used and challenging dataset of MVTec AD, the proposed MBMF achieves competitive image‐level anomaly detection performance (Image‐level Area Under the Receiver Operator Curve (AUROC)) and pixel‐level anomaly segmentation performance (Pixel‐level AUROC). To further evaluate the generalisation of the proposed method, we also implement anomaly detection on the BeanTech AD dataset, a commonly used dataset in the field of anomaly detection, and the Fashion‐MNIST dataset, a widely used dataset in the field of image classification. The experimental results also verify the effectiveness of the proposed method.

Keywords

• computer vision
• convolutional neural nets
• feature extraction
• Gaussian distribution
• unsupervised learning