融合CNN和SRC决策的SAR图像目标识别方法

Decision fusion of CNN and SRC with application to SAR target recognition

  • 摘要: 提出基于卷积神经网络(Convolutional Neural Network,CNN)与稀疏表示分类(Sparse Representation-based Classification,SRC)联合决策的合成孔径雷达(Synthetic Aperture Radar,SAR)目标识别方法。CNN通过深度网络学习SAR图像的多层次特征,进而对其所属的目标类别进行判决。研究表明,CNN在训练样本充足的条件下可以取得很好的识别性能。然而,对于训练样本未能包含的条件,CNN的分类性能通常会出现明显下降。因此,先采用CNN对待识别的测试样本进行分类,再根据输出的决策值(即,各个训练类别对应的后验概率)计算当前分类结果的可靠性。当分类结果判定可靠时,则直接采信CNN的决策,输出测试样本的目标类别。反之,则根据CNN输出的决策值筛选若干候选类别,然后基于它们的训练样本构建全局字典用于SRC分类。对于SRC的分类结果,进一步采用Bayesian融合算法将其与CNN的分类结果进行融合。最终,根据融合后的结果判定测试样本的目标类别。提出方法通过层次化的思路融合CNN和SRC的优势,有利于发挥两者对不同测试条件的优势,达到提高识别稳健性的目的。实验中,基于MSTAR数据集开展测试分析,结果验证了提出方法的有效性。

     

    Abstract: Synthetic aperture radar (SAR) target recognition method based on decision fusion of convolutional neural network (CNN) and sparse representation-based classification (SRC) was proposed. CNN learned the multi-level features of SAR images through the deep networks, and then judged the target category to which it belonged. Studies had shown that CNN could achieve good recognition performance with sufficient training samples. However, for the conditions which were not included in the training samples, the classification performance of CNN usually decreased significantly. Therefore, the test samples to be identified by CNN were used for classification, and then the reliability of the current classification results was calculated according to the output decision value (i.e. the posterior probability corresponding to each training category). When the classification result was judged to be reliable, the decision of CNN was directly adopted and the target category of the test sample was output. On the contrary, several candidate categories were screened according to the decision values output by CNN, and then a global dictionary was constructed based on their training samples for SRC. For the classification results of SRC, the Bayesian fusion algorithm was further used to fuse it with the classification results of CNN. Finally, the target category of the test sample was determined based on the fused result. The proposed method integrated the advantages of CNN and SRC through a hierarchical way, which was conducive to taking advantage of them for different test conditions and improving the robustness of recognition. In the experiment, tests and analysis were carried out based on the MSTAR dataset, and the results verified the effectiveness of the proposed method.

     

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