A detail-preserving and flexible adaptive filter for speckle suppression in SAR imagery

Speckle filtering and detail preservation are two key issues in speckle suppression of Synthetic Aperture Radar (SAR) imagery. Different applications may require different balances between speckle reduction and detail retention. This paper presents a detail-preserving and flexible filter. Both quantitative and qualitative criteria, including speckle reduction, edge retention, texture preservation and visual assessment, were used to evaluate the performance of this adaptive filter. One JERS-1 SAR image and three SIR-C/X-SAR images (L-HH, L-HV and C-HV) were employed in the evaluation. The results show that the proposed filter is slightly better than, or comparable to commonly used filters based on the spatial domain, such as Lee, Frost, Lee-Sigma and Gamma-Map, in terms of detail preservation. Moreover, the proposed filter can achieve a wide range of balances between speckle reduction and detail preservation, and thus is applicable in different applications, including both broad-scale interpretation or mapping and applications in which fine details and high resolution are required. Furthermore, the proposed filter requires no knowledge of speckle standard deviation, which is required in most commonly used filters.