Abstract: A light valve of a film printer has vanes set by the expansion of a plurality of slides parallel to a first axis. The slides are individually actuatable parallel to a second axis transverse to the first axis in a path between a first position and a second position so that the slides expand parallel to the first axis an amount depending upon the combination of slides actuated into the second position and are movable as a unit parallel to the first axis responsive to a trim adjusting knob. A carriage mounted on the light valve is movable parallel to the first axis. A sensor individual to each slide, preferably a light source and a light detector, intersects the path of such slide to indicate whether it is in the first or second position. The carriage is coupled to the trim adjusting knob so the carriage moves parallel to the first axis as the slides are moved as a unit responsive to the trim adjusting knob, to maintain the slides between the respective sensors.

Abstract: Color corrections are executed in a bidirectional film printer responsive to units of color correction information arranged on a data storage tape in the sequence in which the color corrections are to be made in the forward direction of film transport. Units of frame count information each representing the frame at which a color correction is to be made are interleaved with the color corrections on the tape in the sequence in which the color corrections are to be made in the forward direction. One color correction and one frame count at a time are retrieved in pairs; the same pairs are retrieved in both directions of film transport. The frames of the master film are counted during transport and compared with the frame count retrieved from the tape to provide the frame indications at which the color corrections are to be made in the forward direction of film transport.

Abstract: In a bidirectional continuous contact printer for sprocketed film, sprocket holes in a raw film and a master film engage teeth in a sprocket wheel located at an exposure aperture. Between one storage reel and the sprocket wheel, the raw film and the master film pass over tensioning means that draw one edge of the sprocket holes of the raw film and the master film that engage the teeth of the sprocket wheel against such teeth to align the sprocket holes of the films. The tensioning means draw the same edge of the sprocket holes against the teeth in the sprocket wheel during both directions of film transport. In one direction of film transport, the sprocket wheel pulls the film past the exposure aperture, and in the other direction of film transport, the tensioning means pull the film past the exposure aperture. In both directions of film transport, the relative film position is controlled well enough to meet high quality film printing standards.