Secret transmission method of character data in motion picture communication
Kiyoshi Tanaka, Yasuhiro Nakamura, Kineo Matsui · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1991
A secret transmission method of character data is presented in this paper when a series of motion pictures are communicated between two stations. Character data are embedded into the codes of image data to be output from the interframe DPCM encoder, so as to prevent a third party from reading the message; The received data are normally decoded to a picture in higher quality and the message is also decoded at the same time if the receiver knows how to embed it. It results in our experiments that the transmission of character data has little effect on picture quality and the amount of embedded characters will be estimated to be about 20 ~ 30% of bits transmitted in each frame, for example, when SNR is above 30dB.