Computer Techniques for Pseudocolor Image Enhancement

Description of computer methods of creating color separations for pseudocolor transformations, made possible by improvements in microfilm-generating equipment. A halftone process is chosen in which a picture is divided into many small areas and pseudo-random patterns are plotted in each. Twenty-one patterns are designed. The Datagraphix 4060 is programmed to produce 35mm microfilm frames containing plots of the patterns; their densities are established by densitometer reading. The examples described are for creating pseudocolor transformations based on the two-separation process, but the techniques are applicable for processes requiring any number of separations. A FORTRAN program has been written to create a 21-step gray scale, with each step a rectangle constructed from the patterns. Two separations of the gray scale are generated by the 4060, and a color scale is produced using the separations as the red and blue records in the two-separation process. A pseudocolor transformation of an image is created also from digital data. (See also R-596, R-597, RM-5297.)