A Comparative study of Pre-processing Techniques of SAR Images

Synthetic Aperture Radar (SAR) images are high resolution images which are captured by remote sensors mounted on platforms like satellites, helicopters and planes. Electromagnetic waves are transmitted and the echoes reflected from the surface of earth are collected, by the sensor. The quality of image is deteriorated because of the speckle noise which is a type of multiplicative noise which arise due to variations in backscatter from nonhomogeneous cells. The classification of images become difficult as the speckle noise manipulates the statistics of backscatter. It has undesirable effects on Automatic Recognition System (ATR) hence speckle filtering has become the first essential step for SAR image processing such as segmentation and edge detection. This paper presents a survey of various speckle filtering techniques highlighting the key features of each filter. It also lists the filtering criteria and performance statistics that should be used to check the performance of filter.