PURPOSE:To improve picture quality by finding first and second difference between the signal of a main tap and the signal of a tap with large and small delay amounts and the absolute value of the difference, extracting a control signal by performing an operation with the use of the first and second absolute values, and controlling the gain of an output from a filter according to this control signal. CONSTITUTION:As an input signal, a luminance signal is supplied to an input terminal 11, inputted to a (-1) fold coefficient device 15 and inputted to a delay device 12, and the output of the delay device 12 is inputted to one input terminal of respective adders 16a and 17 and to a delay device 13. The output of the delay device 13 is inputted through a (-1)-fold coefficient device 14 to the other input terminal of the adder 16. The outputs of the adders 16 and 17 are respectively inputted through (-1/4)-fold coefficient devices 18 and 19 to an adder 20, and the high frequency component of the luminance signal is induced and inputted to a counter 21. On the other hand, the output of an adder 48 in a sample extraction part passes through a limiter 49 for limiting a numerical value and used as the gain control signal of the counter 21. Thus, the degree of contour emphasis can be freely set and the picture quality can be improved.
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