Abstract: An optical image projector suitable for projecting symbols in an artwork generator comprises a projector head beam relative to which a photographic film 16 can be positioned accurately. The head contains a source 11 of a beam able to illuminate an array of transparencies mounted on a carrier 17 which carrier may be moved between positions accurately defined by a detent mechanism 19, 20 to locate different arrays in the beam. A masking member 21 forming part of the projector head is movable past the carrier and interrupts the beam to prevent projection of all the symbols of the array but has one or more apertures 25 which can be aligned with any one transparency at a time to allow projection. Because the carrier need carry relatively few arrays it can be accurately positioned repeatedly within the projector head to align a symbol accurately with respect to the film while the masking member aperture may be positioned with only moderate accuracy for each of the larger number of transparencies.