任意方向对称差值核的SAR图像边缘提取算法

Abstract

由于现有边缘检测方法多存在对图像噪声的敏感性以及检测边缘的有限方向性等问题，因此在斑点噪声的影响下难以有效检测SAR图像中具有任意方向性且强度相近的区域间边缘。本文提出了一种任意方向对称窗口的SAR图像边缘提取算法。首先，以任意像素在图像中的格点位置为对称中心构建任意方向上的对称窗口；定义各窗口内像素到中心像素距离的核函数；以像素核函数为权重分别计算两对称窗口内像素光谱测度的加权平均值，并定义两者之差的绝对值为该方向上该像素隶属边缘的强度；选取所有方向中最大边缘强度作为边缘像素的判别标准。为去除错误提取的边缘像素，设计基于滤波操作的后处理过程。对模拟图像提取结果的定性及定量分析表明提出算法可在一定程度上克服噪声影响，较为准确地提取任意方向的边缘。

Alternate abstract:

Due to the noise sensitivity and limited directivity of extracted edge presented in current edge detection algorithms, it is difficult to effectively extract the edges with any direction between the two regions with similar intensities from SAR images. In this paper, an edge extraction algorithm of SAR image using two symmetric windows is proposed. The position of grid point of any pixel in SAR image is employed as a symmetric center, then symmetric windows in any direction are constructed by the symmetric center. The kernel function of distances from the central pixel to pixels in each window is defined, then the weighted averages of pixel spectral measurements are calculated for the two symmetric windows, respectively. The absolute value of difference between above averages is employed as edge degree of the central pixel on this direction, and maximum degree from all directions is selected to judge the pixel as an edge pixel. To delete error edge pixels extracted, post-processing procedure based on filtering operation is designed. The interferences of speckle noises are overcome to some extent and edges in random direction are extracted accurately by the proposed algorithm, respectively, which is shown by qualitative and quantitative analysis of the edge extraction results from analog images.