Diffractive Optically Variable Image Device (DOVID)

Also known as a DOVID. The collective term for images that display complex visual effects that change according to the viewing angle, based on the phenomenon of diffraction. These effects are varied and are typically three-dimensional (exhibiting depth as well as width and height), kinetic, multi-channel (in which one image, or part of an image, changes into another) or animated (images with these effects are known as stereograms).