The Fast Neutron/Gamma-ray Radiography (FNGR) technique developed by the Commonwealth Scientific and Industrial Research Organization (CSIRO) provides a new way to screen consolidated air freight for contraband such as illicit drugs and explosives. The combination of density and composition information from the FNGR technique improves discrimination of suspect materials. A full-scale prototype FNGR air cargo scanner has been installed at Brisbane International Airport and is undergoing extensive trials by Australian Customs. In this paper, the technical challenges in developing image processing and display systems for the FNGR scanner are discussed. Image processing techniques have been developed that combine physically motivated corrections and preprocessing steps with modern, non-linear filter techniques. The design of the image display and analysis software is driven by the short time available to study each scanned image, necessitating a powerful, clean, and easy-to-use interface. The CSIRO Air Cargo Scanner is a very promising new technology for bulk cargo screening.
