An Automated Algorithm for Calculating Ocean Contrast Features

In remote sensing of the ocean, contrast in the measured intensity between clean water and other features is used to identify different objects on the ocean surface either directly or indirectly via alteration of the ocean wave spectrum. The damping ratio, a measure of the radar backscatter contrast, is increasingly used to identify oil slicks for operational monitoring as an aid or alternative to visual inspections of images by trained personnel. A new method based upon the statistical properties of the measured signals from the entire ocean surface is proposed as an easily automated method for calculating the contrast. The algorithm, called the histogram method, is demonstrated using L-band synthetic aperture radar (SAR) scenes from the UAVSAR sensor to show that it can handle complex ocean scenes even with fragmented and distributed slicks throughout the scene. Although demonstrated with SAR, the algorithm is sufficiently general to be applied to other types of remote sensing data.