SPECKLE REDUCTION IN MULTIPOLARIZATION, MULTIFREQUENCY SAR IMAGERY

The availability of fully polarimetric SAR data makes it possible to utilize the co-polarized and cross-polarized images for speckle reduction. In this paper an algorithm is developed to take advantage of this polarization diversity to suppress the speckle effect with much less resolution broadening than using spatial filtering. The coupling between polarization channels is minimized by using local intensity ratios. The degree of speckle reduction is similar to two-look or three-look processing. The same algorithm can also be used to process multifrequency polarimetric SAR. For the three-frequency JPL aircraft SAR data (P-, L-, and C-bands), speckle reduction equivalent to six-look processing can be achieved. Further speckle reduction is possible by applying speckle filters in the spatial domain. In addition, a vector speckle filter which operates simultaneously in the polarization and spatial domains is tested. Experimental results with simulated polarimetric SAR as well as one-look and multilook polarimetric SAR data from JPL and NASA demonstrate the effectiveness of these speckle reductions, with minimum resolution broadening and coupling between polarimetric and frequency channels. Comparisons with other algorithms are also made.