Slow-scan television (SSTV) is a method used by amateur radio operators to transmit and receive static pictures via radio in monochrome or color. It is a slower method of still picture transmission, usually taking from about eight seconds to a couple of minutes to transmit one image frame. SSTV operates on voice frequencies and can be used on shortwave, VHF, and UHF radio. The concept of SSTV was introduced in 1957-58 and was initially used in space exploration to transmit images of the far side of the Moon. Today, SSTV systems have evolved and can be used with a personal computer and special software.
https://en.wikipedia.org/wiki/Slow-scan_television