RABASAR: A FAST RATIO BASED MULTI-TEMPORAL SAR DESPECKLING
Abstract
In this paper, a generic method is proposed to reduce speckle
in multi-temporal stacks of SAR images. The method is based
on the computation of a “super-image”, with a large num-
ber of looks, by temporal averaging. Then, ratio images are
formed by dividing each image of the multi-temporal stack
by the “super-image”. In the absence of changes of the ra-
diometry, the temporal fluctuations of the intensity at a given
spatial location are due to the speckle phenomenon. In areas
affected by temporal changes, fluctuations cannot be ascribed
to speckle only but also to radiometric changes. The overall
effect of the division by the “super-image” is the spatial sta-
tionarity improvement: ratio images are much more homoge-
neous than the original images. Therefore, filtering these ratio
images with a speckle-reduction method is more effective, in
terms of speckle suppression, than filtering the original multi-
temporal stack. After denoising of the ratio image, the de-
speckled multi-temporal stack is obtained by multiplication
with the “super-image”. Results are presented and analyzed
both on synthetic and real SAR data and show the interest of
the proposed approach.