Accelerated Sparse-Coding-Inspired Feedback Neural Architecture Search for Hyperspectral Image Classification

Hyperspectral images (HSIs) have spectral variability, which leads to spectral dependence in adjacent and nonadjacent regions, and this dependence is essential for the classification of regions with mixed pixels. Current neural architecture search (NAS) methods have achieved significant advantages in HSI classification, but these methods cannot capture spectral dependence in nonadjacent regions because only use feedforward connections. Meanwhile, the cost of the search process in NAS is proportional to the scale of the search space, which limits the expansion of the search space. To address these issues, we propose a sparse-coding-inspired feedback NAS (SCIF-NAS) method for HSI classification. First, we view HSI samples as sequences and introduce a feedback mechanism in NAS to model the spectral dependence of nonadjacent regions to mitigate the effects of spectral variation. Second, we design several feedforward operations according to the characteristics of HSI, to form the search space together with feedback operations. Meanwhile, a sparse-coding-inspired NAS accelerated strategy is introduced to alleviate the search time burden caused by the expansion of search space. Third, we integrate center loss with cross-entropy loss to construct a hybrid loss function that helps to obtain a better classification boundary. Finally, we conduct experiments on three popular HSI benchmarks, which show that SCIF-NAS outperforms the state-of-the-art methods in HSI classification.