Contrast controller for colour photographic paper printing

摘要

A conventional printer is used with pref. three additional lamps of controlled brightness and duration behind red, green and blue filters. If necessary a fourth additional lamp may be provided with individually controllable brightness and duration, matched to the particular colour paper in use with weak basic filtering. This ensures uniform and simultaneous flattening of all three gradations. Individual colour gradations arising from the computed gamma values can also be controlled and smoothed selectively.