R. Touzi et A. Lopes, THE PRINCIPLE OF SPECKLE FILTERING IN POLARIMETRIC SAR IMAGERY, IEEE transactions on geoscience and remote sensing, 32(5), 1994, pp. 1110-1114
The principle of speckle reduction in polarimetry is reconsidered. It
is shown that polarimetric data can be speckle reduced if and only if
all the elements of the Mueller matrix are filtered, which is equivale
nt to filtering the scattering vector covariance matrix. Assuming that
speckle is multiplicative and stationary, the algorithms proposed in
[1] and [2] are extended to filter the covariance matrix of reciprocal
and nonreciprocal targets on one-look and multilook images. The probl
em of estimation of the first- and second-order statistics of the four
-channel speckle vector is discussed, and a solution is proposed for o
ne-look and multilook images.