Shallow Network Based on Depthwise Overparameterized Convolution for Hyperspectral Image Classification

Recently, convolutional neural network (CNN) techniques have gained popularity as a tool for hyperspectral image classification (HSIC). To improve the feature extraction efficiency of HSIC under the condition of limited samples, the current methods generally use deep models with plenty of layers. However, deep network models are prone to overfitting and gradient vanishing problems when samples are limited. In addition, the spatial resolution decreases severely with deeper depth, which is very detrimental to spatial edge feature extraction. Therefore, this letter proposes a shallow model for HSIC, which is called a depthwise overparameterized convolutional neural network (DOCNN). To ensure the effective extraction of the shallow model, the depthwise overparameterized convolution (DO-Conv) kernel is introduced to extract the discriminative features. The DO-Conv kernel is composed of a standard convolution kernel and a depthwise convolution kernel, which can extract the spatial feature of the different channels individually and fuse the spatial features of the whole channels simultaneously. Moreover, to further reduce the loss of spatial edge features due to the convolution operation, a dense residual connection (DRC) structure is proposed to apply to the feature extraction part of the whole network. Experimental results obtained from three benchmark datasets show that the proposed method outperforms other state-of-the-art methods in terms of classification accuracy and computational efficiency.