HDTV real-time image compression using dual-transmission channels

A method of sending high-definition video signals over a conventional broadcast channel plus a separate augmentation channel is described. It is shown that this technique maintains full NTSC compatibility in the primary channel for terrestrial transmitters and cable links, but adds control flags, which can be used by both HDTV television and a new generation of NTSC receivers, to identify area of the picture in motion. The augmentation signal is provided as spectral components, rather than spatial components, in order to allow the transmission system to closely match the spatio temporal characteristics of the eye. It is also shown that the bandwidth of the augmentation channel can be significantly reduced while still providing full high-definition quality (i.e. at least twice conventional resolution both horizontally and vertically). It is concluded that these principles can be implemented for other worldwide transmission standards such as PAL or SECAM