An analysis of input–output characteristics of scanned systems is presented from the input camera to the output reproducer. The system characteristics are developed in terms of both spatial coordinates and spatial frequency responses in both dimensions. These include the effects of the scanning apertures of both the camera and the reproducer, in addition to the electrical filter on the resultant signal. The effects of time varying input patterns are also considered in terms of the temporal responses of the camera and the phosphor characteristic of the reproducer.