PURE RED COLOR DETECTION CIRCUIT AND COLOR COMPENSATION CIRCUIT USING THE SAME

摘要

Red color saturation is increased and red color with higher purity can be reproduced by composing: a red color detection circuit (1) for detecting a red color signal having higher purity by inputting color differential signals (R-Y) and (B-Y) modulated by color subcarrier, subtracting the absolute value of the (B-Y) signal from the positive polarity component of the (R-Y) signal and removing the negative part of the substracted signal; Y signal compensation block including: first gain controller (50b) for controlling the output signal amplitude of red color detection circuit (1) and a subtracter (50a) for subtracting the output signal of first gain controller (50b) from a luminance signal Y; an (R-Y) signal compensation block including: second gain controller (51b) for controlling the output signal amplitude of red color detection circuit (1) and an adder (51a) for adding the output signal of second gain controller (51b) and the input (R-Y) signal; and a (B-Y) signal compensation block including: third gain controller (52b) for controlling the output signal amplitude of red color detection circuit (1), a polarity inverter (52c) for inverting the output signal polarity of third gain controller (52b), a switch circuit (52d) for selecting either input signal or output signal of polarity inverter (52c), a polarity discriminator (52e) for discriminating the polarity of the input (B-Y) signal and controlling switch circuit (52d) and an adder (52e) for adding the output signal of switch circuit (52d) and the input (B-Y) signal.