> > Due to the immense bandwidth required to transmit as much > > information as a frame of high-resolution film can store, it is > > unlikely that future systems will immitate film. They may, > > however, be more akin to FM radio, which transmits NOT a signal, > > but the DIFFERENCE in the source from moment to moment. > > This is wrong. FM does transmit a signal directly, rather than > any difference. Both FM and AM radio modulate a carrier to transmit > their signal, an AM transmitter changes the amplitude of the carrier > in proportion to the input signal, an FM transmitter changes the > frequency of the carrier in proportion to the input signal. This is not a forum in radio theory, but your explanation confirms what I said, which is that FM transmits a change in frequency reflecting the difference in the source from moment to moment. The important point is the concept of relative, versus absolute transmissions. In current video, the entire image is refreshed in bands and frames. In film, the entire image is presented in one frame. But in a relative transmission, pixels which do not change would remain constant.