Video signals can be contaminated by a variety of noise sources, even if they are digital. Sources of noise can include storage media, image acquisition devices (e.g. cameras, digitizers, etc.), transmission channels (e.g. broadcasting, satellite links, cable networks, statistical multiplexers), and receiving and recording equipment. Noise can have different characteristics, such as additive white gaussian noise from electronic equipment, salt and pepper noise from over-the-air transmissions, video grain, and packet loss or frame-loss in digital transmissions over unreliable channels.
