Sony Corporation

Yoshitaka Kanemoto

Ichitaro Sato

Masafumi Ishige

Tamio Yokoyama

When separating a composite video signal into a luminance signal component and the chrominance signal component by the use of filtering, a high frequency cross-talk component of the luminance signal is present in the chrominance signal and this may be cancelled using a horizontal correlator that imparts time delays and detects maximum and minimum levels relative to a reference level. In such luminance cross-talk cancellation by means of the horizontal correlator the usable chrominance signal length is shortened by almost one wave length out of four, thereby reducing the usable chrominance signal each time such luminance/chrominance signal separation occurs in a dubbing operation, for example. By utilizing two chroma separators in series each including a nonadditive mixer circuit, the resultant output from the second chroma separator circuit has substantially the same length as the portion of the composite video signal fed as the input. As a further safety factor in preventing the chrominance signal from being produced with excessive noise, a time delayed version of the composite video signal is level checked with the output of the second chroma separator unit and the signal having the lesser level is produced as the output.

Luminance/chrominance separator

A chroma signal is supplied to a comb-filter for eliminating noise component in the chroma signal. The output signal of the comb-filter and the input chroma signal are both supplied to a correlation circuit. The correlation circuit outputs the same signal as the output of the comb-filter when the input chroma signal and 1H delayed chroma signal have line correlation between each other. The correlation circuit further outputs the same signal as the input chroma signal at the front end portion of the chroma signal and outputs nothing at the back end portion, though the comb-filter output trails 1H delay signal at the back end portion thereof.

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Kanagawa, Japan

Yoshitaka Kanemoto