Automatic hue control circuit

Details Automatic hue control circuit Automatic hue control circuit

1976-05-05

1978-04-11

Griffin, Robert L.

Facsimile and static presentation processing

Static presentation processing

Attribute control

H04N 9535

Patent

active

040841782

ABSTRACT:
An automatic hue control circuit is disclosed for a color television receiver, wherein the flesh-tone signals of the reproduced image are enhanced by spreading the phase angle between the R-Y and the B-Y reference signals before applying them to their respective demodulators. In one aspect of the invention, the flesh-tone enhancement by phase-shifting the R-Y and B-Y signals occurs only for positive values of the flesh-tone signals. In a further aspect of this invention, a simplified automatic hue control circuit is disclosed as comprising a matrix for receiving, respectively, the R-Y, the G-Y and the B-Y color signals to obtain a DC quiescent voltage with which the flesh-tone signal, as indicated by the sum of the R-Y and the G-Y signals, is compared to render conductive a switch, illustratively in the form of a diode, whereby the phase-shift is imparted to the R-Y and B-Y reference signals. In particular, the desired phase shift between the R-Y and B-Y signals is effected only when the flesh-tone signals are of a positive value, whereby a more accurate color reproduction is provided.

REFERENCES:
patent: 3663744 (1972-05-01), Harwood
patent: 3950780 (1976-04-01), Freestone
patent: 3950781 (1976-04-01), Miyamoto
patent: 3996608 (1976-12-01), Harwood

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