LAUSR

In this article, we present a content-sensitive superpixel generation method with edge penalty and the contraction–expansion search strategy (EPCES) for synthetic aperture radar (SAR) images. Specifically, the edge information can be obtained by our previously proposed ratio-based edge detector with recurrent guidance filter, which has been proven to be robust to speckle noise and capable of detecting weak edges in low-contrast areas. The content-sensitive superpixel seeds’ initialization method is proposed with respect to the heterogeneous state of the SAR imagery, benefiting from which EPCES can generate an exact number of superpixels set by the user and the fine details can be preserved well. In EPCES, a new dissimilarity with edge penalty is defined to generate the superpixels with better edge adherence. Rather than adopting the conventional clustering method based on local $k$ -means, we propose the contraction–expansion search strategy (CES), which explicitly utilizes the continuity information contained in neighboring pixels and enforces the connectivity of the superpixel without any postprocessing step. With the aid of the CES, our proposed method can attain superpixels with low computational cost and high edge adherence. Experimental results on both synthetic and real-world SAR images verify that the proposed method consistently performs favorably against several state-of-the-art methods in terms of both quality and efficiency.