Evaluation of Adaptive Polarimetric Speckle Filters over Agricultural Areas

Abstract

Speckle suppression in PolSAR images is an important step for the extraction of meaningful information. Polarimetric speckle filtering is important not only for speckle reduction but also for preserving the polarimetric information and estimate the statistical properties between channels. The fully polarimetric Maximum A Posteriori (MAP) speckle filters namely Wishart Gamma MAP, Wishart DE MAP were evaluated for their efficiency in preserving statistical information in polarimetric SAR image. The filters developed by based on Gamma/Gaussian-distributed scene models reduce speckle noise, while preserving the radar reflectivity, the textural properties, and the spatial resolution, especially in strongly texture SAR images. For the estimating the Statistical information between two filters, five speckle suppression indices namely Equivalent Number of Looks, Speckle Suppression Index, Speckle Suppression and Mean Preservation Index, Edge Enhancing Index, Image Detail Preservation Coefficient were applied on the polarimetric Radarsat-2 quad pol. data over two test sites dominated by agricultural areas. The results show that, Wishart DE MAP yielded better ENL values and all other indices performed similarly with no significant variations.