ABSTRACT
Novelty-filters are elements of optical signal processing systems that serve to recognize or isolate real-time changes in the structure of images. Analogues of such filters are widely distributed in animals as primary elements of information processing. For example, frogs with Novelty-filters detect flying insects with high accuracy. The humans also use Novelty-filters to remove from the visual field the images of the blood vessels located on the front of the sensitive retina of the eyeball. All Novelty-filer based image processing units discussed in this chapter use photorefractive crystals as active elements. This chapter considers the features of the process of coupling of two interacting waves on dynamic holograms recorded in photorefractive crystals, which will allow us to understand the physical foundations of linear processing systems based on Novelty- filters. The principle of such a Novelty-filter is based on the phenomenon of strong coupling of a weak informative wave with a strong pump wave in a photorefractive crystal.
