Color correction for photographic reproduction

Tone values of a photographic image are stored in a frame store (20) and retrieved from the frame store to produce a corresponding video display. A mouse (17) or trackball is used to locate a point on display and a gamma correction curve look up table (22R,22G,22B) is used to interactively show the effect of color correction. Adjustment can be made via lighter and darker switches (14,15) on the mouse or trackball. These switches subtract or add a bump function to the gamma correction curve in the selected color density plane. The bump function is displaced by the measured tone value in order to achieve more flexible control over the color correction.