OPTIMIZATION OF THE GAMMA-GAMMA MAP FILTER FOR SAR IMAGE CLUTTERS

The Gamma-Gamma Maximum a posteriori filter provides an estimate of th e speckle-free radar cross-section when both the radar reflectivity an d the speckle distributions are gamma-distributed. In this Letter, it is shown that a factor greater than two in precision can be typically gained in the radar cross-section estimate in the case of natural land Synthetic Aperture Radar (SAR) clutters. This is accomplished by usin g the normalized logarithmic estimator which is a more accurate index than the coefficient of variation to deduce the local heterogeneity pa rameter.