Sonar image enhancement via acoustic color
A novel method to enhance synthetic aperture sonar (SAS) images using the acoustic color of the returns from different targets is presented. The method enhances the SAS image using the internal absorption properties of targets in a way that enhances the differences between different types of targets (target signature). First, the algorithm detects the highlights in the sonar image as is found from the beam‐formed processed image. These highlights represent edges of targets. Then the analysis is performed only at the echo returns which correspond to edges of targets. For each edge the raw data corresponding to the return from that edge is found. This data which has not yet been pulse‐compressed using the pinging signal is analyzed using a detailed frequency representation. Then, the frequency representation of the pinging signal is subtracted from it so that a resulting frequency representation of the difference between the pinging signal and the returning signal is obtained. A normalization of the returne...