测绘学报

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基于核独立成分分析的极化SAR图像相干斑抑制

张中山1,余洁1,燕琴,孟云闪1,赵争3   

  • 收稿日期:2010-04-30 修回日期:2010-09-16 出版日期:2011-06-25 发布日期:2011-06-25
  • 通讯作者: 张中山

Research on Polarimetric SAR Image Speckle Reduction Using Kernel Independent Component Analysis

  • Received:2010-04-30 Revised:2010-09-16 Online:2011-06-25 Published:2011-06-25

摘要: 相干斑抑制是极化合成孔径雷达图像(POLSAR)处理过程中的一个非常必要的环节,运用传统的多视处理法与空域滤波方法,滤波后的图像存在着边缘模糊现象,而常见的极化域滤波法没有利用图像的相位信息。为了提高极化合成孔径雷达图像相干斑抑制的效果,本文提出了基于核独立成分分析(Kernel Independent Component Analysis,KICA)的极化SAR图像相干斑抑制方法。该方法将三个通道的极化信息作为输入数据,经过KICA变换得到三个独立分量,取相干斑指数最小的分量作为滤波后的信息图像。由于将核函数引入到独立成分分析(Independent Component Analysis, ICA)中,使在ICA中无法线性可分的信息在高维空间中达到线性可分。为了验证KICA方法的有效性,文中采用旧金山地区的AIRSAR数据与日本新泻地区的PISAR数据分别进行试验,并用相干斑指数和边缘保持系数从客观上进行了评价。实验表明,与ICA算法相比,KICA算法具有更好的滤波效果和保持边缘信息的能力。

Abstract: Speckle reduction is a very essential part during the process of the polarimetric synthetic aperture radar (POLSAR) image, but the traditional common methods have each defects. In order to improve the accuracy of polarimetric synthetic aperture radar image speckle reduction, a polarimetric SAR image speckle reduction method using kernel independent component analysis (KICA) is presented. This method uses the polarimetric information of three channels as its input data, obtains three independent components after KICA conversion, and takes the one with the smallest speckle index as the filtered results. Due to the introduction of kernel function, the information that can not be linearly separated using independent component analysis (ICA) algorithm achieves linearly separated in the kernel high-dimensional space. For the purpose of verifying the validity of the KICA method, the AIRSAR data of San Francisco area and the PISAR data of Japan’s Niigata region were tested. The efficiency was objectively evaluated by the speckle reduction index and the edge preservation index. And the experiment results show that the image edges are retained better and the speckles are removed more effectively with the method of KICA algorithm compared with the ICA algorithm.