Abstract: The additive color system includes a light source providing three component light beams. The component beams are combined to form a composite beam. Three variable-density electrooptical filter units are provided, each arranged in the path of a respective one of the component beams. Each filter unit attenuates the respective component beam in dependence upon a control voltage applied to its control electrodes. A selecting device selects the transmission value to which the filter units are to be set. A circuit generates corresponding control voltages and applies them to the control electrodes of the filter units, and includes compensating circuits for compensating for repeatability errors in the response of the filter units.

Abstract: The additive color system includes a light source providing three component light beams. The component beams are combined to form a composite beam. Three variable-density electrooptical filter units are provided, each arranged in the path of a respective one of the component beams. Each filter unit attenuates the respective component beam in dependence upon a control voltage applied to its control electrodes. A selecting device selects the transmission value to which the filter units are to be set. A circuit generates corresponding control voltages and applies them to the control electrodes of the filter units, and includes compensating circuits for compensating for repeatability errors in the response of the filter units.

Abstract: Three component beams are taken off three sides of a single filament light source, individually attenuated, colored in respective ones of the three additive primary colors red, blue and green and recombined to form three superimposed component images of the filament light source. The three superimposed images of the filament light source are positioned at the light source location for the printing camera. Adjacent the light source the three component beams pass through three apertures spaced from the source far enough to be located at a position where the light field is uniform. Three superimposed real images of these apertures are formed down-path of the superimposed images of the filament light source and coincident with the plane of the transparency to be printed.