Photoreproduction

The science of photo‐reproduction has undergone revolutionary developments during the past few years. Although photography was invented in the early nineteenth century, it has been only in the last few years that one could snap a picture and obtain a finished photograph in less than a minute. The development of simple office‐copying techniques for the reproduction of letters and other documents is of very recent origin. Perhaps less well known but certainly of equal importance are the new photographic techniques for obtaining a matrix for printing, that is, a printing plate obtained by photographic means. It is the purpose of the present article to acquaint the reader with the scientific basis of photoreproduc‐tion techniques. Since historically, and perhaps economically, photomechanical techniques are of greatest importance, we shall consider them first. At the same time, it might be wise to review the essentials of printing techniques.