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Abstract
The U.S. Geological Survey has, for many years, been involved in printing photoimages without using conventional halftone screens. The purpose for using screenless printing in photoimage mapmaking has been to print finer detail that enables the user to make a better interpretation of the imagery. In an attempt to meet this objective, we have experimented with many photographic and screen processes and in the past several years have used the Howson-Algraphy, Inc., Alympic Gold positive plates along with their Contone developer to lithographically print photographic imagery, without the use of a screen. This screenless process uses the structure of the grain of photosensitive plates to form microscopic random dots that comprise the printed image. Changes and modifications to the manufacturer’s recommended process are included in the detailed procedures for calibration of the positive subtractive press plates, evaluation of the continuous-tone film, and quality control review during the reproduction process. With the experience gained over the past several years of printing by the screenless process, the reported guidelines and procedures have been standardized to aid in making this form of screenless printing a predictable process.
Notes
Any use of trade names, trademarks or company names on this report is for descriptive purposes only and does not constitute endorsement by the U.S. Geological Survey.
Paper submitted for a Symposium on “Photography in the Printing Industry” organized by the Scientific and Technical Group of The Royal Photographic Society, 13-18 September 1983 in New College. Oxford, England.