Describes a simple, rapid, comparatively inexpensive three-separation method for transforming black-and-white photographs into pseudocolor transparencies, with each shade of gray represented by a different color. Since the eye can distinguish many more colors than shades of gray, such pseudocolor prints allow observers to extract more information from a photograph. The three-separation technique manipulates the density of the original, uses modified masking techniques to achieve red, blue, and green separations, and prints them successively in register on color negative material for the final pseudocolor transparency. This can be done in less than two hours in a modestly equipped photo laboratory, semi-manually, and would be suitable for use in a mobile reconnaissance unit. A fully automatic processor would reduce the time sharply. The report includes color plates of sample pseudocolor transformations--chromosome karyotypes, breast X-rays, aerial photographs--showing how the pseudocolor can be manipulated to bring out interesting details. Two other pseudocolor techniques will be reported separately. 47 pp. Ref.