Design considerations of a slick camera for detection of images of oil slicks floating on the ocean surface

This paper describes a TV camera system that automatically picks out exclusive images of oil slicks floating on the surface of the sea. The slick camera includes two band-pass filters (BPFs), two charge coupled device (CCD) arrays and a differential image circuit that produces an absolute value of a difference signal between two output images from CCDs. The operating principle is based on the fact that, due to the multiple-beam interference from the oil film, there is a marked difference of intensity between light reflected from the surface of the sea and that from an oil film. Two types of BPF, i.e., a space-invariant BPF and a space-variant BPF, were investigated and it was found that the space-variant BPF was far superior to the space-invariant BPF.