Frederick R. Ruckdeschel

Characterizing halftone noise: a technique.

A measurement technique is presented that permits the characterization of the regularity of low-coverage halftone patterns common to many reproduction processes. The technique is based on a scanning microdensitometer, which examines individual halftone cells and compares them with their neighbors. It is believed, but not shown, that the number descriptor obtained is monotonically related to visual judgments of halftone noise. Also presented are measurements pertaining to copy created by various processes, in particular, xerography. Comparisons indicate that the Cromalin proofing process is capable of extremely high structural quality halftones, while xerography can approach the noise level of moderate structural quality lithography under special conditions.