Gamma correction bandpass amplifier circuits

Claim 1

In a television camera of the type employing an image pickup device and a spatial filter adjacent said device to intercept the light from a scene prior to application of said light to said pickup device, said camera employing means for scanning said scene to cause said pickup device to provide at an output terminal thereof a plurality of carrier signals each one of which is representative of a different color present in said scene, said carrier signals also accompanied by a signal component indicative of the illumination of said scene, said pickup device having a given gamma coefficient which undesirably serves to cause the amplitude of said carrier signals to decrease from a desired value when scenes with high illumination are scanned, in combination therewith apparatus for controlling the amplitude of at least a first of said carrier signals according to scene illumination, comprising: a. an amplifier circuit having an input, output and common electrode, b. means coupled to said input electrode for applying thereto one of said carrier signals, c. means coupled to said common electrode responsive to the magnitude of said signal component indicative of the illumination to increase the gain of said amplifier to said carrier signal to thereby compensate for the undesirable effect of said gamma coefficient of said vidicon.