Abstract: A synchronous pulse generator responsive to a set condition of a memory produces a burst of N timing pulses within a period of time T for each M revolutions of a video disc player turntable. The timing pulses are converted to an analog voltage for application to the vertical drive circuit of an imaging device which receives one horizontal control signal for each burst. Feedback circuitry resets the memory when the number of pulses produced reaches a predetermined value whereby each time the memory is set a raster of constant height is formed having a line resolution dependent upon selection of the parameter N. The parameter M may be independently selected for controlling an effective vertical field of view represented by the displayed image. A video signal reproduced by the player may be added to the analog voltage for producing a contourgram of a selected segment of a disc being played or used for Z-axis modulation of the imaging device for producing gray scale images.