Color television system having adaptive filters in the transmitter encoder and in the receiver decoder

Claim 1

In a color television system which includes a transmitter and a receiver and wherein a color video signal is transmitted having luminance (Y) and chrominance (C) components for each of successive pixels on successive scanning lines of a video picture, the C signal having a frequency band overlapping part of the frequency band of the Y signal, the Y signal and C signal respectively including frequencies which are clustered at respectively different harmonics of the scanning line frequency for portions of the video picture having high vertical correlation, such harmonic frequencies shifting so as to increasingly overlap in portions of the video picture having increasingly less vertical correlation; said transmitter including an encoder for combining the Y and C signals to form the transmitted video signal, and said receiver including a decoder for deriving the Y and C signals from the received video signal; the improvement characterized in that: said encoder comprises at least one adaptive filter to which one of said Y and C signals is supplied as an input, and said decoder comprises at least one adaptive filter to which the received video signal is supplied as an input, each of said adaptive filters comprising: a multiline delay for receiving the input signal to such filter and deriving therefrom respective line signals corresponding thereto for respective ones of a plurality of successive scanning lines of the video picture; a line comb filter for receiving said line signals and deriving therefrom a comb-filtered signal which only includes those frequency components of the line signals having a particular phase relationship on said successive scanning lines; a fading circuit for receiving said comb-filtered signal and one of said line signals and combining them in variable relative proportions to derive a corrected signal, such variable proportioning ranging between a corrected signal consisting of only said comb-filtered signal and a corrected signal consisting of only said one line signal; a detector circuit for deriving from said line signals a vertical difference signal (VDS) of a magnitude corresponding to the degree of vertical correlation of said line signals; a processor circuit for deriving from said VDS signal an adaptive control signal (ACS) for controlling said fading circuit to establish said relative proportioning in accordance with the magnitude of said ACS signal; and means including a bandpass filter for combining said one line signal with said corrected signal produced by said fading circuit so as to derive an output signal constituting the output of said adaptive filter, said output signal being said one line signal comb-filtered to a maximum extent consistent with the degree of vertical correlation of said line signals.