MiniMaxAD: A Lightweight Autoencoder for Feature-Rich Anomaly Detection

Previous unsupervised anomaly detection (UAD) methods often struggle with significant intra-class diversity; i.e., a class in a dataset contains multiple subclasses, which we categorize as Feature-Rich Anomaly Detection Datasets (FRADs). This is evident in applications such as unified setting and unmanned supermarket scenarios. To address this challenge, we developed MiniMaxAD: a lightweight autoencoder designed to efficiently compress and memorize extensive information from normal images. Our model utilizes a large kernel convolutional network equipped with a Global Response Normalization (GRN) unit and employs a multi-scale feature reconstruction strategy. The GRN unit significantly increases the upper limit of the network's capacity, while the large kernel convolution facilitates the extraction of highly abstract patterns, leading to compact normal feature modeling. Additionally, we introduce an Adaptive Contraction Loss (ADCLoss), tailored to FRADs to overcome the limitations of global cosine distance loss. MiniMaxAD was comprehensively tested across six challenging UAD benchmarks, achieving state-of-the-art results in four and highly competitive outcomes in the remaining two. Notably, our model achieved a detection AUROC of up to 97.0\% in ViSA under the unified setting. Moreover, it not only achieved state-of-the-art performance in unmanned supermarket tasks but also exhibited an inference speed 37 times faster than the previous best method, demonstrating its effectiveness in complex UAD tasks.