A process of color separating a transmitted light or reflected light from a color original into so-called three primary colors of R (red), G (green), and B (blue) by an ordinary optical method using, for example, red, green and blue-purple color filters, making negative or positive films for blue printing (cyan), red printing (magenta), and yellow printing (yellow) basing on the lights of three colors of R, G, and B, and then making each color separated printing plate using each film thus obtained has hitherto been widely performed. In the process, photographic light-sensitive materials having light-sensitive characteristics in the whole wavelength region of visible light of from 400 n.m. to 700 n.m. are required.
Hitherto, as the light-sensitive materials having such light-sensitive characteristics, silver salt light-sensitive films are used. However, the silver salt light-sensitive films are expensive as compared to ordinary films and in the case of using such silver salt light-sensitive films, it is difficult to handle the films in bright room. In the case of using a silver salt light-sensitive material, it cannot be directly used as a printing plate but a process of developing and fixing the silver salt light-sensitive film and then printing the positive or negative images formed on the silver salt film onto an original printing plate such as a presensitized printing plate (PS printing plate), etc., to make a printing plate is required.
These sequential operations per se, are troublesome and require specific apparatuses for each operation. An expense for these apparatuses, and personnel, as well as material cost for light-sensitive films cannot be disregarded.
This invention has been achieved in view of forgoing problems to provide color separating printing plate directly from the color originals in a short time.