Lofargram line tracking by multistage decision process

The authors deals with the issue of spectral line tracking in a time/frequency sonar image, the so-called lofargram (LOw Frequency Analysis Representation). The approach, based on feature grouping theory, consists of studying the line notion with respect to the minimization of a cost function Phi . A multistage decision process is used to extract optimal paths from an image window. These optimal paths are defined according to Phi and have a high chance of belonging to a spectral line. Then, a temporal processing integrates these observation windows to supply, after filtering, an image cleared of locally incoherent noise. Thus, the spectral line perception is drastically enhanced, even with a low signal to noise ratio.<>