HyperTaFOR: Task-Adaptive Few-Shot Open-Set Recognition With Spatial-Spectral Selective Transformer for Hyperspectral Imagery

Open-set recognition (OSR) aims to accurately classify known categories while effectively rejecting unknown negative samples. Existing methods for OSR in hyperspectral images (HSI) can be generally divided into two categories: reconstruction-based and distance-based methods. Reconstruction-based approaches focus on analyzing reconstruction errors during inference, whereas distance-based methods determine the rejection of unknown samples by measuring their distance to each prototype. However, these techniques often require a substantial amount of training data, which can be both time-consuming and expensive to gather, and they require manual threshold setting, which can be difficult for different tasks. Furthermore, effectively utilizing spectral-spatial information in HSI remains a significant challenge, particularly in open-set scenarios. To tackle these challenges, we introduce a few-shot OSR framework for HSI named HyperTaFOR, which incorporates a novel spatial-spectral selective transformer (S3Former). This framework employs a meta-learning strategy to implement a negative prototype generation module (NPGM) that generates task-adaptive rejection scores, allowing flexible categorization of samples into various known classes and anomalies for each task. Additionally, the S3Former is designed to extract spectral-spatial features, optimizing the use of central pixel information while reducing the impact of irrelevant spatial data. Comprehensive experiments conducted on three benchmark hyperspectral datasets show that our proposed method delivers competitive classification and detection performance in open-set environments when compared to state-of-the-art methods. The code is available online at https://github.com/B-Xi/TIP_2025_HyperTaFOR.