Spectral–Spatial Out-of-Distribution-Based Unsupervised Band Selection Method for Hyperspectral Anomaly Detection

Hyperspectral anomaly detection (HAD) aims to highlight the pixels that are different from the surrounding pixels without any prior information. However, as a hyperspectral image (HSI) tends to possess a huge data volume in the spectral domain, the dimension curse is inevitable in HAD. The unsupervised band selection (UBS) method is an effective tool to avoid the dimensionality curse in the HAD task. To obtain a more robust band subset without the help of any HAD detectors, we propose a spectral–spatial out-of-distribution (OOD)-based UBS method for HAD (HADUBS), which can acquire the optimal band subset in a more straightforward way. Our key observation is that the OOD term of pixels can reveal the differences and similarities of anomaly representation ability of different bands. Hence, we developed an OOD-based feature subspace representation module to obtain latent feature spaces with a better indication of the anomaly detection ability. Moreover, we introduced a UBS strategy called mutual information (MI)-based local outlier factor (MILOF) to significantly improve the discriminative ability of the selected band subset by investigating the locally sparse prior of anomalies. Extensive experimental results on five common HAD datasets demonstrate the superior performance of HADUBS. The source code will be made publicly available at https://github.com/duang33/HADUBS.