second delay line second delay line means ii for further delaying a signal delayed by the first delay line by a second predetermined delay time a delay line driver circuit delay line driving means iii for driving the first and second delay lines and a matrix mixer matrix mixing means iv for mixing three signals of the input signal to the delay line the output signal from the first delay line and an output signal from the second delay line at a matrix mixture ratio of u03b1 1 u03b1 1 and outputting a mixed signal as a contour compensating signal further the above matrix mixture ratio in the matrix mixer is controlled in response to an automatic gain control detection voltage applied from an agc circuit incorporated in an image pickup tube for instance fig2 b shows an embodiment of the basic contour compensating circuit shown in fig2 a the circuit shown in fig2 b comprises an input terminal 6 a delay line driver circuit including an amplifier 7 and an impedance r o a first delay line 8 a second delay line 9 a matrix mixer 10 composed of a first multiplier 10 1 a second multiplier 10 2 and an adder 10 3 a compensating signal adder 11 and an output terminal 12 video signals e g brightness signals outputted from an image signal generating element e g an image pickup.