A comprehensive review of SAR image filtering techniques: systematic survey and future directions

The synthetic aperture radar (SAR) is an active instrument used in various atmospheric conditions and can generate images with high resolution. SAR is a satellite imaging technology, working under all weather conditions throughout the day and night. It operates at microwave (or radar) frequencies. For a SAR image, speckle noise is a natural characteristic that corrupts the radiometric quality from the image and can affect the visualization and analysis. Speckle is usually modeled as a multiplicative noise that reduces SAR image quality. The suppression of the speckle is a pre-processing step. The speckle noise reduction process is known as despeckling. There are methods available to reduce speckle noise. This paper reviews various speckle reduction methods by highlighting their merits and demerits. © 2021, Saudi Society for Geosciences.