Exposure Control in a Multi-Stage Photographic System

The use of controlled exposure in microfilming original documents offers a practical method for producing high-contrast images at subsequent printing stages with constant exposure times. This type of control, used for the three-stage generation of images in a developmental photo-image retrieval system, has given excellent results for documents which have uniform line-density contrast. For variable contrast documents, an analysis of the variations and variable exposures used in microfilming is necessary. The details of the analysis are described in this paper.