A Review on various Speckle Filters used for despeckling SAR images

Nowadays Synthetic Aperture Radar (SAR) images are used extensively for various important applications like terrain navigation , land cover classification, environment monitoring like oil spill detection, flood detection, military surveillance etc. SAR images get corrupted by the speckle noise, which appears as bright and dark spots on images and hence the visual quality of the images get degraded. This leads to the improper functioning of various feature extraction and classification algorithms which are used to classify SAR images into desired classes depending on the nature of applications. So removal of speckle noise from SAR images is one of the crucial steps in the pre-processing of SAR images. Although many despeckling filters have been proposed by various researchers working in this field till date but still there is a need for a filter that can deal with all the constraints associated with the process. In this paper we have discussed and summarized all the advantages and technicalities associated with various filters and have also performed a comparative study of the results obtained by performing qualitative and quantitative analyses of output images generated by applying various filtering algorithms on same set of noisy SAR images.