Scalar image processing filters for speckle reduction on synthetic aperture sonar images

High resolution images provided by synthetic aperture sonar (SAS) sensors are of great interest, especially for the detection, location and classification of mines lying on the sea bed. But these data obtained by an active imagery system are highly corrupted by a noise called the speckle. To reduce this noise and suppress the spurious reflections it generates on the images, we propose to use different algorithms based on image processing techniques. Several image processing filters are tested and discussed. A comparative study of the results obtained on real SAS data is presented. The different filters are evaluated both visually and in terms of variance reduction.