Photographic graininess reduction by super-imposition

Abstract

A method of reducing the graininess of a photographic print and increasing resolution in low contrast regions is described. The method involves the printing of more than one negative frame to produce one print. This requires a series of negatives with identical detail coverage in the area to be printed. The success of the method depends largely on the precision of the solution of the registration problem. Each negative is printed in turn, using the normal exposure, partitioned in as many parts as there are negatives to be printed. Each negative must be registered as exactly as possible in the image area. Four different aerial emulsions were used to obtain the 35-mm negatives for the superimposition printing technique. Kodak films used were: Tri X-RP Aercon, Super XX-RP Aerial Recon, Plus X Aerocon (SO 1166), and SO-1213. The exposure versus resolution characteristics and the basic sensitometric curves were developed for these films prior to exposure of the final series of negative frames. The negatives were exposed under identical conditions with the exception of lens openings and shutter speeds at an object to image ratio of 160 to 1. The camera was a Contax IIA with a 50-nm F/2 Sonnar lens. The camera exposure settings were: Tri-X, F/16, 1/250 second; Plus X, F/16, 1/100 second; SO-1213, F/11, 1/50 second. Due to the level of brightness of the target, the camera lens was not used at its best aperture. No filter was used. [TRUNCATED].