Fast Algorithm for Inverse Two-Dimensional S Transform and Its Application in Time-Frequency Filtering for SAR Image Despeckling

S transform is a time-frequency representation which has been applied in various fields, yet suffers the problem of time and resource consumption. In order to overcome this problem and facilitate its application in image analysis, we introduce a fast algorithm for inverse twodimensional S transform. A two-dimensional S transform time-frequency filter for Synthetic aperture radar (SAR) image despeckling is proposed on the basis of this fast algorithm. Synthetic and actual SAR images are both used to quantitatively evaluate its performance. The proposed algorithm is compared with several classical algorithms with better results both in speckle noise reduction and detail preservation.