SAR（合成孔径雷达）图像斑点抑制一直是SAR图像应用中的一个重要课题。近二十几年来，伴随着SAR的发展和应用，涌现出了大量的斑点抑制算法。这些算法可分为两类：一类是基于单通道数据；另一类是基于多通道数据。对相干斑抑制问题进行了全面系统的研究，并侧重于多极化SAR图像的斑点抑制，归纳总结了近十几年来国内外所出现的多极化SAR图像斑点抑制算法，并对各种算法的性能进行了分析和比较。

Speckle reduction is always one of the important tasks in the application of SAR(Synthetic Aperture Radar) images . With the development and application of SAR, many speckle filtering algorithms have been proposed aimed at speckle reduction in lately twenties of years. These algorithms can be divided into two categories: one is based on single channel data, and the other is based on multi channel data. Comprehensively and systemically, this paper investigates the principles of speckle reduction in polarimetric SAR images. All of the algorithms proposed in recent years are summarized and their performances are analyzed and compared.