1. An optical parallax correlation system having an optical axis and using coherent light, Fourier transforming lenses, and holographic recording to correlate images of stereophoto transparencies and to reproduce indicia of image element relative positions in a correlation plane, the improvement comprising: means defining a sampling slit aperture disposed in front of a transparency and mounted for transverse movement with respect to the optical axis; display-recording means disposed at the correlation plane and also mounted for movement transverse to the optical axis; and means defining a parallax selection slit aperture mounted in front of said display-recording means and also mounted for movement transverse to the optical axis.