A Quantitative Study of Combined Exposures in Halftone Negative Making

Read to the Symposium on photomechanical processes held jointly by the Scientific and Technical Group of the Royal Photographic Society and the British Federation of Master Printers on Thursday, 27 January, 1955.

Abstract

In all halftone work it is customary to combine several exposures-for instance a highlight, a detail and a flash exposure-in order to control both the contrast and the shape of the tone reproduction curve. The result of combining these exposures is well known qualitatively, but the quantitative study seems to be imperfect. In 1950 J. A. C. Yule worked out a method of calculating the results of several exposures and a formula showing the relationship of the flash and the image exposures.

In this paper a formula for calculating the results of combined exposures with the ordinary cross-line screen is described and a method of exposure control with a new exposure computer is shown.

Notes

Read to the Symposium on photomechanical processes held jointly by the Scientific and Technical Group of the Royal Photographic Society and the British Federation of Master Printers on Thursday, 27 January, 1955.