Contour restoration apparatus

Claim 2

The contour restoration apparatus according to Claim 1 further comprises a nonlinear processing circuit to which the output of said adder and the maximum and minimum values output by said maximum and minimum detection circuits are input, said nonlinear processing circuit outputting the maximum value if the output signal of said adder is larger than the maximum value, the minimum value if the output signal of said adder and the output signal of said adder if it is between the maximum value and the minimum value.

Claim 3

The contour restoration apparatus according to Claim 2 further comprises a location detection circuit for comparing input video signal and output signals of said plurality of delay circuits with the maximum value detected by said maximum value detection value and comparing input video signal and output signals of said plurality of delay circuits with the minimum value detection circuit, said location detection circuit controlling the gain of the gain controller at zero if the maximum value and the minimum values are detected at the same side when seen from a location of the center signal among input video signal and output signals of said plurality of delay circuits.

Claim 4

The contour restoration apparatus according to Claim 2 further comprising a contour amplitude detection circuit for detecting a difference between the maximum value and the minimum value detected by said maximum value detection circuit and minimum value detection circuit and controlling the gain of said gain controller according to said difference detected.

Claim 5

The contour restoration apparatus according to Claim 2 further comprising a contour extraction circuit to which the signal locating centrally among input video signal and output signals of said plurality of delay circuits and signals locating before and after the center signal are input, said contour extraction circuit comprising multipliers for multiplying each of three signals input thereto with a predetermined coefficient and an adder for adding three signals multiplied, another gain controller for amplifying the output of said contour extraction circuit with a predetermined gain, another adder for adding the output of said another gain controller and the center signal, a contour amplitude circuit for detecting a difference between the maximum value and the minimum value detected by said maximum value detection circuit and minimum value detection circuit and for outputting a coefficient determined according to the difference detected, and a mixer for mixing the output l of said nonlinear processing circuit and the output r of said another adder according to an equation kn × l + (1-kn) × r wherein kn is a coefficient given by said contour amplitude detection circuit.

Claim 6

A contour restoration apparatus comprising an input terminal for a string of video signals having been sampled with first sampling interval, a sampling rate converter for converting said string of video signals to a string of video signals having second sampling interval which is shorter than said first sampling interval, a plurality of delay circuits connected to said sampling rate converter in series, each of said plurality of delay circuits having a delay time determined in accordance with said second sampling interval a maximum value detection circuit for detecting a maximum value among output signal of said sampling rate converter and output signals of said plurality of delay circuits, a minimum value detection circuit for detecting a minimum value among signals same as those input to said maximum value detection circuit, a mean value circuit for calculating a mean value of output signals of said maximum and minimum value detection circuits, a subtraction means for subtracting said mean value from an output signal of selected one of said plurality of delay circuits, a gain controller for amplifying the output of said subtraction means with a predetermined gain, an adder for adding the output of said gain controller and said output signal of selected one of said plurality of delay circuits, and an output terminal for outputting the output of said adder as a contour restrated signal.

Claim 7

A contour restoration apparatus comprising an input terminal for video signals; a plurality of delay circuits connected in series to said input terminal, each of said plurality of delay circuits having a predetermined delay time for a signal input thereto, a maximum value detection circuit for detecting a maximum value among input video signal and output signals of said plurality of delay circuits, a minimum value detection circuit for detecting a minimum value among signals same as those input to said maximum value detection circuit, a mean value circuit for calculating a mean value of output signals of said maximum and minimum value detection circuits, a comparator for comparing an output signal of selected one of said plurality of delay circuits with said mean value calculated by said mean value circuit, a selector for selecting either of said maximum value and minimum value in accordance with the output of said comparator, and an output terminal for outputting the output signal of said selector.

Claim 8

A contour restoration apparatus comprising an input terminal for video signals; a signal level detection circuit being comprised of a plurality of delay circuits connected in series to said input terminal, a maximum value detection circuit for detecting a maximum value among input video signal and output signals of said plurality of delay circuits, and a nimimum value detection circuit for detecting a minimum value among signals same as those input to said maximum value detection circuit; a first contour restoration circuit being comprised of a plurality of delay circuits connected to said input terminal in series, a plurality of multipliers for multiplying predetermined coefficients to outputs of said plurality of delay circuits, an adder for adding outputs of said plurality of multipliers, a gain controller for amplifying the output of said adder with a predetermined gain, and another adder for adding the output of selected one of said plurality of delay circuits; a second contour restoration circuit being comprised of a plurality of delay circuits connected to said input terminal in series, a plurality of multipliers for multiplying predetermined coefficients to outputs of said plurality of delay circuits, an adder for adding outputs of said plurality of multipliers, an auto gain controller for amplifying the output of said adder with a gain outomatically set, a control signal generation circuit for generating a control signal for said auto gain controller of said second contour restoration circuit which outputs of said maximum value and minimum value detection circuits and said first contour restoration circuit are input, said control signal generation circuit controlling the gain of said auto gain controller to a second value smaller than a first value if the output of said first contour restoration circuit is larger than the maximum value or smaller than the minimum value, and an output terminal for outputting the output of said another adder of said second contour restoration.

Claim 9

The contour restoration apparatus according to Claim 8 wherein one set of plural delay circuits, plural multipliers and an adder connected to said plural multipliers are used in common for those of said first and second contour restoration circuits.

Claim 10

The contour restoration apparatus according to Claim 8 further comprising a contour amplitude detection circuit for detecting a contour amplitude by subtracting the minimum value from the maximum value and for outputting a coefficient in accordance with te contour amplitude detected thereby, and a switching circuit for outputting either of the output of the second contour restoration circuit and the input video signal delayed so that the timing thereof coincides with that of the output of the second contour restoration circuit in accordance with the coefficient output from said contour amplitude detection circuit.