How Big is a Halftone Hole?

The structure of silver halftone dots on photographic film has been studied using photomicrography, microdensitometry, and computer-aided plotting of density contours. Halftone dots are shown to have variable density as well as highly variable edge gradation or acutance. The density of the hole is therefore quite variable. Some of the typical halftone dots and holes illustrated were electronically generated on scanners; some were screened on scanners with lasers or broad-band light; others were conventionally screened by direct, indirect, or rapid-access systems. Further, differences between lith and high contrast, continuous-tone (rapid-access) processed dots are shown. Chemically etched halftone dots are studied, along with contact dots on positive and negative films. The conclusion is presented that the densities of dots and holes are important aspects of a halftone image and are often overlooked when considering the various photographic steps on the way to producing ink on paper.