Analysis of shadow contrast for synthetic aperture sonar imagery

The contrast, or depth of shadows, in synthetic aperture sonar (SAS) imagery is arguably as important to image interpretation as the focus of the backscattered returns. The maximum contrast that can be achieved is determined by a combination of hardware, software, and environmental parameters. In this paper, the impact of these parameters on shadow contrast is quantified, and the contrast ratio is developed as a metric to predict a system's capacity to form imagery with well-defined shadows. A representative SAS is described, and its contrast ratio is investigated over a limited set of environmental and hardware parameters. This contrast ratio analysis can serve a tool for predicting system performance, determining the best dynamic range for display, and bounding the effects of manufacturing tolerances and motion errors.