Adaptive PAL - or NTSC - comb filter

DETAILED DESCRIPTION In an illustrated preferred embodiment according to the principles of the invention, when conditions likely to cause the described disturbances or artifacts are present within an image structure of an input video signal, a subtraction stage which develops a separated luminance signal receives either a band pass filtered (non-comb filtered) chrominance signal or, in a PAL system under certain conditions, no chrominance signal instead of a comb filtered chrominance signal.
The decision as to which of the signals is received by the subtraction stage is made by a switching circuit the operation of which is determined by prescribed parameters of the input signal.
A control signal for the switching circuit is developed by a phase comparator network which responds to signals provided by a chrominance comb filter network including plural 1H delay circuits for developing 1H and 2H delayed output signals.