Convolutional neural network for spectral–spatial classification of hyperspectral images

Hyperspectral images (HSIs) have great potential in military reconnaissance, land use, marine monitoring and many other fields. In recent years, the convolutional neural network (CNN) has been successfully used to classify hyperspectral data and achieved remarkable performance. However, the limited labeled samples of HSI lead to the small sample size problem, which remains the major challenge for CNN-based HSI classification. Besides, most CNN models have large number of parameters needed to be learned, which cause high computational cost. To address the aforementioned two issues, a novel CNN-based HSI classification method is proposed. The proposed classification method has several distinguishing characteristics. First, the proposed method can robustly extract spectral and spatial features of the HSI simultaneously. Second, in the proposed CNN architecture, all convolution layers are 1 × 1 convolution layer except the first one, which can greatly reduce the number of network parameters, thus accelerating the training and testing process. Third, a small convolution and feature reuse (SC-FR) module is developed. The SC-FR module is composed of two composite layers and each composite layer consists of two cascaded 1 × 1 convolution layers. Through cross-layer connecting, the input and output features of each composite layer are concatenated and passed to the next convolution layer, thus achieving feature reuse mechanism. Cross-layer connection increases information flow and the utilization rate of middle-level features, which enhances the generalization performance of CNN effectively. Experimental results on three benchmark HSIs demonstrate the competitive superiority of the proposed method over several state-of-the-art HSI classification methods, especially when training samples are limited.