A Model for the Random Video Process

For problems concerning the transmission of video signals, it is often desirable to know the statistical distribution of power in the frequency domain for the signal process. It is convenient to have a model, involving only a few essential parameters, which will satisfactorily characterize the power spectral density of the random video signal. This paper proposes a model for the random picture and derives expressions for second-order statistical properties of the video signal obtained from a conventional scanning operation on the picture. The properties of typical picture material make valid certain approximations which lead to especially simple, closed-form expressions for power spectral density. The continuous part of the power spectral density is expressed as a product of three factors, characterizing separately the influence of point-to-point, line-to-line, and frame-to-frame correlation. For parameters representative of typical picture material there is observed an extreme concentration of power near multiples of the line scan and frame scan rates. An illustrative example of the use of the model in an optimum linear filtering problem is included.