Hue correction system

Claim 2

In a color television receiver with chroma channel means for supplying a chroma signal modulated along a pair of modulation axes having a predetermined included angle in a quadrant which contains flesh hues, a hue correction circuit, comprising: oscillator means for generating a pair of fixed phase reference signals having an included angle different than said predetermined included angle in the quadrant which contains flesh hues; wide angle demodulator means responsive to said pair of reference signals for demodulating said chroma signal along two demodulation axes at said different included angle to develop color signals with altered hues including altered flesh hues; and correction means responsive to hues contained in a different quadrant adjacent said quadrant which contains flesh hues for altering the amplitude of at least some of said color signals to correct for altered hues in said different quadrant.

Claim 3

The hue correction circuit of claim 1 wherein said correction means comprises means for reducing the amplitude of at least some of said color signals in proportion to the amplitude of the hues contained in said different quadrant.

Claim 4

The hue correction circuit of claim 1 wherein said oscillator means generates a third fixed phase reference signal which is phase offset from said pair of reference signals, and said correction means comprises correction demodulator means responsive to said third reference signal for demodulating said chroma signal along a third demodulation axis to develop a correction signal in response to hues in the region adjacent said third axis, and coupling means located between said correction demodulator means and said wide angle demodulator means for altering the amplitude of at least some of said color signals in response to said correction signal.

Claim 5

The hue correction circuit of claim 3 wherein said correction demodulator means comprises a single sided phase detector for detecting hues in a range narrower than any quadrant defined by said modulation axes.

Claim 6

The hue corRection circuit of claim 4 wherein said single sided phase detector is responsive to hues in the green-cyan region, and said coupling means includes subtraction means for reducing the amplitude of at least one of said color signals in proportion to the saturation of hues in said region.

Claim 7

THe hue correction circuit of claim 4 wherein said single sided phase detector includes rectifier means for clamping the amplitude of said third reference signals, semiconductor means, and biasing means interconnecting said semiconductor means and rectifier means to pass chroma signals coinciding in phase with said third reference signal.

Claim 8

The hue correction circuit of claim 1 wherein said wide angle demodulator means develops a pair of color difference signals corresponding approximately to B-Y and R-Y, said correction means in response to green hues develops a correction signal having an amplitude proportional to the saturation of the green hues, and subtraction means for reducing the absolute value of said B-Y color difference signal in proportion to the amplitude of said correction signal.

Claim 9

A hue correction circuit for a color television receiver with chroma channel means for supplying a chroma signal, comprising: oscillator means for generating first, second and third reference signals each at a different phase with respect to a common reference signal; first demodulator means coupled to said oscillator means for demodulating said chroma signal along a first demodulator axis coinciding with said first reference signal to develop a first color signal; second demodulator means coupled to said oscillator means for demodulating said chroma signal along a second demodulator axis coinciding with said second reference signal to develop a second color signal; third demodulator means coupled to said oscillator means for demodulating said chroma signal along a third demodulator axis coinciding with said third reference signal to develop a third color signal; circuit means coupled between said third demodulator means and one of said first and second demodulator means for modifying the amplitude of the color signal developed thereby in response to said third color signal; and output utilization means responsive to at least the modified amplitude color signal for producing a color display.

Claim 10

A hue correction circuit for a color television receiver with chroma channel means for supplying a chroma signal, comprising: oscillator means for generating first, second and third reference signals each at a different phase with respect to a common reference signal; first demodulator means coupled to said oscillator means for demodulating said chroma signal along a first demodulator axis coinciding with said first reference signal to develop a first color signal; second demodulator means coupled to said oscillator means for demodulating said chroma signal along a second demodulator axis coinciding with said second reference signal to develop a second color signal; third demodulator means coupled to said oscillator means for demodulating said chroma signal along a third demodulator axis coinciding with said third reference signal to develop a third color signal; circuit means coupled between said third demodulator means and one of said first and second demodulator means for modifying the amplitude of the color signal developed thereby in response to said third color signal; and output utilization means responsive to at least the modified amplitude color signal for producing a color display.

Claim 11

The hue correction circuit of claim 8 including matrix means coupled to said first and second demodulator means for developing a matrixed color signal from the modified amplitude and the remaining of the first and second color signals, said output utilization means being responsive to the modified amplitude color signal, the remaining of the first and second color signals, and the matrixed color signal to produce a three color display.

Claim 12

The hue correction circuit of claim 9 wherein said third demodulator means comprises a singla sided phase detector means for demodulating said chroma signal along only one polarity of said third demodulator axis to cause the third color signal to have an amplitude proportional to the saturation of hues located adjacent said third axis, said circuit means reducing the absolute value of one of said first and second color signals in response to said third color signal.

Claim 13

The hue correction circuit of claim 8 including means for coupling the modified color signal, the unmodified of the first and second color signals, and the third color signal to said output utilization means, whereby said third demodulator means produces both a color output signal and a correction signal.

Claim 14

The hue correction circuit of claim 11 wherein said first demodulator means produces a first color difference signal corresponding approximately to B-Y, said second demodulator means produces a second difference color signal corresponding approximately to R-Y, said third demodulator means produces a color difference signal corresponding approximately to G-Y, and said circuit means reduces the absolute magnitude of said B-Y color diffeRence signal in proportion to the level of said G-Y color difference signal.