电子学报 ›› 2021, Vol. 49 ›› Issue (9): 1809-1817.DOI: 10.12263/DZXB.20201281

• 学术论文 • 上一篇    下一篇

基于斑点统计特性保持的SAR影像迭代滤波

李玉, 王姝运, 赵泉华   

  1. 辽宁工程技术大学测绘与地理科学学院遥感科学与应用研究所, 辽宁 阜新 123000
  • 收稿日期:2020-11-16 修回日期:2021-04-07 出版日期:2021-10-21
    • 作者简介:
    • 李 玉 男, 1963年3月出生, 吉林省长春人. 现任辽宁工程技术大学教授、博士生导师. 主要研究方向为遥感数据处理理论与基础应用研究, 包括空间统计、随机几何、模糊数学在遥感数据建模与分析中的应用、目标几何与特征提取.E-mail: liyu@lntu.edu.cn
      王姝运 女, 1994年11月出生, 河北省张家口人. 硕士. 主要研究方向为遥感图像处理. E-mail:761367857@qq.com
      赵泉华 女, 1978年出生, 河北省承德人, 现任辽宁工程技术大学教授、博士生导师. 主要研究方向为遥感图像建模与分析以及随机几何在遥感图像中的应用. E-mail:zqhlby@163.com
    • 基金资助:
    • 国家自然科学基金青年基金项目 (41801233)

Iterative Filtering of SAR Image Based on Speckle Statistical Characteristic Preservation

LI Yu, WANG Shu-yun, ZHAO Quan-hua   

  1. Institute for Remote Sensing Science and Application, School of Geomatics, Liaoning Technical University, Fuxin, Liaoning 123000, China
  • Received:2020-11-16 Revised:2021-04-07 Online:2021-10-21 Published:2021-09-25
    • Supported by:
    • Youth Fund of National Natural Science Foundation of China (41801233)

摘要:

合成孔径雷达(Synthetic Aperture Radar,SAR)影像中的斑点现象是地物后向散射信号相互干扰产生的,其虽然类似噪声却涉及地物目标的散射特征.同一地物目标的散射特征可通过斑点统计分布模型来刻画,因此降噪过程中可通过恢复影像斑点的统计分布特性来保留斑点包含的地物散射信息.基于该思想,提出一种基于斑点统计特性保持的SAR影像迭代滤波算法.该算法假设给定SAR影像的统计分布函数是先验已知的,即建模为混合Gamma分布,其分布参数可利用影像的像素值估计;接着基于构建的混合Gamma分布模型,运用EM(Expectation Maximization)算法分割影像中的同质区域;再针对不同同质区域,选取拟合误差较大的灰度级,根据分割结果计算像素值为该灰度级的像素的密度,判断其是否是异常像素,并对异常像素运用Frost滤波器进行降噪.重复上述步骤,直到滤波后的影像直方图较好地服从统计分布函数.GF?3和Radarsat?2 SAR影像数据实验结果表明,该算法在保证影像质量的前提下,不仅能获得较好的统计建模结果,而且较好地抑制了相干斑噪声,实现影像降噪.

关键词: 合成孔径雷达(SAR), 相干斑抑制, 影像直方图, 统计分布函数, 异常像素检测, 统计特性保持

Abstract:

The speckle phenomenon in synthetic aperture radar (SAR) images is caused by the mutual interference of backscattering signals of ground objects. Although it is similar to noise, it involves the scattering characteristics of ground objects. The scattering characteristics of the same ground object can be described by the speckle statistical distribution model. Therefore, in the process of noise reduction, the scattering information of the ground object contained in the speckle can be preserved by restoring the statistical distribution characteristics of speckle. Based on this idea, an iterative filtering method of SAR image based on speckle statistical characteristic preservation is proposed. The proposed method assumes that the statistical distribution function of a given SAR image is known a priori, namely the mixture Gamma distribution, and its distribution parameters can be estimated by the pixel values of the image. Then, the EM(Expectation Maximization) algorithm is used to segment the SAR image based on the mixture Gamma distribution, so as to obtain the homogeneous regions in the image. Subsequently, for different homogeneous regions, select the gray levels with larger fitting errors, calculate the densities of the pixels whose values are the gray levels according to the segmentation results, and judge whether they are abnormal pixels, and the abnormal pixels are filtered by Frost filter. Repeat above procedure until the histogram of filtered image fits the statistical distribution function well. Experimental results of GF-3 and Radarsat-2 SAR image show that, on the premise of maintaining image quality, the proposed method can not only obtain better statistical modeling results, but also suppress speckle well and achieve image denoising.

Key words: Synthetic Aperture Radar (SAR), speckle reduction, image histogram, statistical distribution function, abnormal pixels detection, statistical characteristic preservation

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