Methods and devices for time-varying selection and arrangement of data points with particular application to the creation of ntsc-compatible hdtv signals

Abstract

Processes for selecting, manipulating and arranging data points or pixels derived from information bearing signals are useful to reduce the bandwidth of, or improve the perceived quality of, such a signal as transmitted and displayed. The techniques utilize time-varying sampling schemes and take into account the characteristics of the human visual system. For each information frame, a subset ( ) of all possible data points ( ) is selected ( ). A further subset of active data points ( ) is selected ( ) for which data will actually be sampled. The active points ( ) are further divided ( ) into points for which a value will be transmitted (x-points) ( ) and points which will be sampled but for which no separate value will be transmitted (o-points) ( ). A mathematical association between the x-points and o-points is made ( ) and new values to be transmitted are calculated for the x-points ( ). The parameters of the selection and association processes are varied in a non-trivial manner and the, now modified, cycle repeated ( ) for subsequent data frames. In particular, the techniques may be used to process a high-definition television signal prior to its storage, or transmission over a low-bandwidth channel.