Recently, deep convolutional neural network (DCNN)-based methods have achieved much success in hyperspectral image (HSI) classification, when sufficient labeled samples are provided during training. However, due to the expensive cost of labeling in HSIs, only limited labeled samples can be given in practice, which often causes these methods to be overfitting. To address this problem, we present a new HSI classification method in this study, which is constructed in the following two steps. First, we establish a data mixture model to augment the labeled training set quadratically and train a DCNN-based classifier on it. Then, through randomly sampling the coefficient in the data mixture model, we obtain several independent classifiers and fuse them with a voting strategy to produce the final classification results. Since both data augmentation and classifier fusion are effective to deal with limited samples, the proposed method shows superior performance in the classification of HSIs, which can be demonstrated by the experimental results on two benchmark HSI data sets.

When confronted with limited labelled samples, most studies adopt an unsupervised feature learning scheme and incorporate the extracted features into a traditional classifier (e.g., support vector machine, SVM) to deal with hyperspectral imagery classification. However, these methods have limitations in generalizing well in challenging cases due to the limited representative capacity of the shallow feature learning model, as well as the insufficient robustness of the classifier which only depends on the supervision of labelled samples. To address these two problems simultaneously, we present an effective low-rank representation-based classification framework for hyperspectral imagery. In particular, a novel unsupervised segmented stacked denoising auto-encoder-based feature learning model is proposed to depict the spatial-spectral characteristics of each pixel in the imagery with deep hierarchical structure. With the extracted features, a low-rank representation based robust classifier is then developed which takes advantage of both the supervision provided by labelled samples and unsupervised correlation (e.g., intra-class similarity and inter-class dissimilarity, etc.) among those unlabelled samples. Both the deep unsupervised feature learning and the robust classifier benefit, improving the classification accuracy with limited labelled samples. Extensive experiments on hyperspectral imagery classification demonstrate the effectiveness of the proposed framework.

Deep neural networks (DNNs) have underpinned most of recent progress of hyperspectral image (HSI) classification. One premise of their success lies on the high image quality without noise corruption. However, due to the limitation of imaging sensor and imaging conditions, HSIs captured in practice inevitably suffer from random noise, which will degrade the generalization performance and robustness of most existing DNN based methods. In this study, we propose a dynamic super-pixel normalization based DNN for HSI classification, which can adaptively relieve the negative effect caused by various types of noise corruption and improve the generalization performance. To achieve this goal, we propose a dynamic super-pixel normalization module, for a given super-pixel which normalizes the inner pixel features using parameters dynamically generated based on themselves. By doing this, such a module enables adaptively restoring the similarity among pixels within the super-pixel corrupted by random noise through aligning their feature distribution, thus enhancing the generalization performance on noisy HSI. Moreover, it can be directly plugged into any other existing DNN architectures. To appropriately train the proposed DNN model, we further present a semi-supervised learning framework, which integrates the cross entropy loss and Kullback-Leibler divergence loss on labeled samples with the infomation entropy loss on the unlabeled samples for joint learning to well sidestep over-fitting. Experiments on three benchmark HSI classification datasets demonstrate the advantages of the proposed method over several state-of-the-art competitors in handling HSIs under different types of noise corruption.

Hyperspectral imagery (HSI) classification is one of the fundamental applications in remote sensing domain, which aims at predicting the labels of unlabeled pixels in an image with a classifier trained on a certain amount of labeled pixels. However, due to the expensive cost on manual labeling, only limited labeled pixels can be obtained in real applications, which is prone to result in the training of classifier to be overfitting. To address this problem, we present an intraclass similarity structure representation-based HSI classification method. First, according to the intraclass spectrum similarity of pixels, we establish a mixed labels-based annotation model. Given some randomly selected unlabeled pixels, we employ the proposed annotation model to assign each pixel a mixed label from the top-two possible classes, and then augment the original training set with those labeled pixels. On the augmented training set, we train a deep convolutional neural network-based classification model. With several individual rounds of the annotation and classifier training procedures, we obtain several independent classification models and predict the final labels as their fusion results with a voting strategy. Experimental results demonstrate the effectiveness of the proposed method in terms of HSI classification with few training samples.

Hyperspectral image (HSI) contains an abundant spatial structure that can be embedded into feature extraction (FE) or classifier (CL) components for pixelwise classification enhancement. Although some existing works have exploited some simple spatial structures (e.g., local similarity) to enhance either the FE or CL component, few of them consider the latent manifold structure and how to simultaneously embed the manifold structure into both components seamlessly. Thus, their performance is still limited, especially in cases with limited or noisy training samples. To solve both problems with one stone, we present a novel dual-level deep spatial manifold representation (SMR) network for HSI classification, which consists of two kinds of blocks: an SMR-based FE block and an SMR-based CL block. In both blocks, graph convolution is utilized to adaptively model the latent manifold structure lying in each local spatial area. The difference is that the former block condenses the SMR in deep feature space to form the representation for each center pixel, while the later block leverages the SMR to propagate the label information of other pixels within the local area to the center one. To train the network well, we impose an unsupervised information loss on unlabeled samples and a supervised cross-entropy loss on the labeled samples for joint learning, which empowers the network to utilize sufficient samples for SMR learning. Extensive experiments on two benchmark HSI data set demonstrate the efficacy of the proposed method in terms of pixelwise classification, especially in the cases with limited or noisy training samples.