Reproduction of Gray with Halftones.

A primary requirement, which any color reproduction process must fulfill, is that it accurately reproduce the neutral scale. With the increasing use of color reproduction processes which eliminate or reduce manual color correction, a better knowledge of the requirements for reproducing the gray scale is desired. With halftone images, a particular gray value may be produced in an infinite number of different ways since two variables exist: (1) Dot area, (2) Ink film thickness. In addition, the photographic requirements for reproducing the gray scale vary with printing conditions. For example, the kind of paper, the type of plate, the inks to be used, and the process - either gravure, Ietterpress, or lithography - determine what the gray-reproduction requirements shall be. This paper is divided into two parts: (1) a general review of the theoretical requirements for the reproduction of gray, and (2) a complete account of the experimental results and the method used in determining the gray-reproduction requirements for a particular set of litho-offset conditions.