REFERENCE WHITE CONTROL AND COLOR REPRODUCTION OF COLOR TV RECEIVERS.

The color primaries and the reference white of modern color TV receivers are different from those of National Television System Committee (NTSC) color system specifications. These differences increase luminance and chromaticity errors in modern display. The two following methods for reproducing natural color and the desired white have been developed. (1) Non-linear color signal decoding: The chromaticity and luminance errors of a reproduced color by linear corrective decoding are analyzed quantitatively. Non-linear corrective decoding is proposed which reproduces improved color pictures with high fidelity and less errors. (2) Non-linear white control: The desired white reproduction is investigated, and a gamma switching circuit which controls reference white depending on the luminance level is proposed. The white tracking controlled by this circuit is suitable for human vision.