Integratable color correction circuit

DETAILED DESCRIPTION What is claimed is: 1.
In a television receiver having a source of color difference signals, a color difference demultiplexer for developing R-Y and B-Y color difference signals therefrom, an I matrix circuit supplied with said R-Y and said B-Y color difference signals and enveloping therefrom an I axis signal having a DC component and a varying AC component indicative of the amount of flesh tone; a color signal correction circuit for automatically adjusting the B-Y color difference signal as a function of the I axis signal, said color signal correction circuit having an input supplied with the output of said I matrix circuit; a comparator having a first input coupled to the output of said I signal matrix circuit; a counter operatively coupled to the output of said comparator; a digital-to-analog converter connected to the output of said counter and supplying a second input of said comparator and being connected to said color signal correction circuit, said digital-to-analog converter developing a DC potential corresponding to the DC level of said I axis signal; and means for enabling said comparator and said counter during a portion of said color difference signals when there is no color present.




Description:
BACKGROUND OF THE INVENTION This invention relates in general to color signal correction circuits and, in particular, to a color signal correction circuit that is entirely integratable.
In the NTSC color television system, as in any color television system, human flesh tones are difficult to produce consistently well.
This is due to a variety of well-known factors.
Unfortunately, the human eye is very sensitive to errors in flesh tone, and any tendency for flesh tones to shift toward either green or purple is instantly recognizable.
Consequently, many circuits for augmenting flesh tone colors have been developed and used.
Such circuits generally operate on the basis that flesh tones are primarily located along the +I axis, which essentially encompasses orange tones