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This paper describes various forms of line drawing representation, compares different schemes of quantization, and reviews the manner in which a line drawing can be extracted from a tracing or a photographic image. The subjective aspects of a line drawing are examined. Different encoding schemes are compared, with emphasis on the so-called chain code which is convenient for highly irregular line drawings. The properties of chain-coded line drawings are derived, and algorithms are developed for analyzing line drawings to determine various geometric features. Procedures are described for rotating, expanding, and smoothing line structures, and for establishing the degree of similarity between two contours by a correlation technique. Three applications are described in detail: automatic assembly of jigsaw puzzles, map matching, and optimum two-dimensional template layout. [ABSTRACT FROM AUTHOR]

The article provides information on the identification of microcards containing classified material. In order to promote security of classified material produced on microcards, such cards should be easily recognized. The simplest man net with which to accomplish this is by having the cards in colors, such as red for secret, yellow for confidential and assigning other colors as necessary. The actual process of coloring the cards can be done with dyes. The dyes should be those having no effect other than coloring on the photographic image, paper stock or gelatin. Some dyes used experimentally were, croisine scarlet and Tintex. The dye was dissolved in hot water to make a highly concentrated solution, then cooled to room temperature and filtered before use.

The article reports that the Rapid Selector as originally built was not completely satisfactory because of the complexity and expense of the mechanism required for satisfactory reproduction of frames of 61 meter which were close together on the master film. The problem is one of removing an exposed frame of takeoff film after the two microsecond flash, and before another flash comes along to spoil the images by double exposure. However, some 11 frames pass in one-thirteenth of a second, and if two or more of them were on the same subject multiple exposures on one frame would result.