Transmission of data, such as television signal data representative of an image scanned, usually requires a substantial amount of data to be transmitted before a sufficiently useful reproduction of the image can be produced from a receiver receiving the data. Various systems have been proposed in which data derived from scanning an image is compressed before transmission, expanded upon reception and reproduced. The viewer at the receiver still has to wait for much of the received data to be received and reproduced before he can view a useful image.
It is an object of the invention to provide an improved encoding method and apparatus.