Sidescan Sonar Image Enchancement Using a Decomposition Based on Orthogonal Functions. Applications with Chebyshev Polynomials

A method is presented to remove from sidescan sonar images of the seafloor, artifacts that are clearly unrelated to the backscattering properties of the seafloor. A spectral analysis performed on a ping by ping basis proved to be well suited to the problem. The technique relies on a decomposition using Chebyshev polynomials. This stochastic method does not require a priori knowledge of deterministic parameters. It deals with the low spatial frequency components of the image whose wavelengths are not very small compared to the swath width. Applications to sidescan sonar images obtained with the SeaMARC LI system are presented