Abstract: A contour restoration apparatus has a plurality of delay circuits connected in series. Maximum and minimum value detection circuits detect maximum and minimum values among an input video signal and output signals of the delay circuits. A mean value circuit is used to calculate a mean value of the of the maximum and minimum values. The mean value is subtracted from a delayed signal having a delay time of one-half of a delay time obtained from all the delay circuits. An adder is used to add the result of the subtraction to the delayed signal. A non-linear processing circuit processes the output of said adder and the maximum and minimum values. The non-linear circuit outputs the output signal of the adder, if the output signal of said adder is between the maximum value and the minimum value. A contour extraction circuit multiplies a signal located centrally among the input video signal, the output signals and the signals located before and after the input signal with a predetermined coefficient.

Abstract: A contour restoration circuit comprises an input terminal, a plural of delay circuits connected to the input terminal in series, a maximum value detection circuit, a minimum value detection circuit, a mean value calculating the mean value from the maximum and minimum values, a subtractor for subtracting the mean value from the input video signal, a gain controller for the subtracted signal, an adder for adding the gain controlled signal to the input video signal and an output terminal.