There is a technique for making color prints in which different local regions of the image have variations in reflectance or some optical characteristics so that the image varies as a function of viewing position. The procedure involves a combination of mechanical and photographic operations which are slow and tedious. A set of negatives must first be made to isolate each different local region, that is, to have a reflectance variation. Positives are made from the negatives and combined with them to form photographic masks which are used to expose an embossing film master through a grid of lines. Each local region which is to have a reflectance variation is exposed through grid lines inclined at a preselected angle. When completed, the film embossing master contains a set of parallel lines in each local region which have a reflectance variation. Within each region, the lines are parallel to each other. The angle of the lines changes from region to region but many regions may use the same line angle. This embossing film master is used to make a debossing plate that embosses a foil according to the regional line patterns Then color separations have to be made from the color image, e.g. cyan, magenta, yellow and black. Each of these is used to created a color separation film master by exposing a film through the local region line patterns established on the embossing film master. Thus each color separation film master has a color distribution identical with that of the original color image but lined in accordance with the line patterns designated for each particular local region. These color separation film masters are used to create printing plates for printing the final color image on the embossed foil with the embossed lines and the color lines in registration to produce an image whose various regions distinguish themselves by the varied manner in which they reflect light as the viewer shifts his viewing angle or that of the incident light. This is the technique taught in U.S. patent application Ser. No. 07/304,900, filed Jan. 31, 1989, entitled "Variable Color Print and Method of Making Same", by Robert J. Mancuso, which is a Continuation of U.S. patent application Ser. No. 002,783, filed Jan. 13, 1987, of the same title, and incorporated herein by reference. Although the explanation so far illustrates the technique only with respect to varying the reflectance, this is not a limitation as the film masters may be used to vary other optical characteristics to get a similar result in the final color print.
USPTO Backgrounds
USPTO Backgrounds