小波分析在SAR图像边缘检测中的应用

Application of Wavelet in SAR Image Edge Detection

边缘提取是图像分析的基础 ,但由于SAR图像中存在强的、乘性的相干斑噪声 ,使在光学图像中有效的边缘检测器对于SAR图像不再适合 .基于小波变换的边缘检测器 ,由于采用了固定的阈值 ,在SAR图像边缘提取的同时也会检测出很多虚假的边缘 ,特别是在图像的亮区 .因而 ,本文提出了具有恒定误警率的自适应变化阈值 ,并基于小波变换的多分辨率分析 ,有效地提取边缘特征 .仿真实验表明该算法对于有相干斑污染的SAR图边缘提取是很有效的 .

The influence of speckle within SAR images should be taken into consideration during edge extraction. Since wavelet transform has satisfactory local characteristics for the analysis to non periodical or sudden change signals, the multi scale edges of images can be extracted. But, at the same time, a lot of false edges would be extracted by this method. The effect of speckle on edge extraction is suppressed by adopting threshold of constant false alarm rates. Simulation results clearly testify that the new algorithm is efficient.