Noise filter
AssigneeFernseh Inc.
InventorsRichard B. Warnock, John A. Briggs
Life of this patent
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Abstract
A recursive digital filter is disclosed for removing noise from an incoming television signal. The filter couples the incoming television signal to a subtracter without substantial attenuation of the television signal. The subtracter also receives at an input an attenuated difference signal comprising a selected amplitude of the difference between the incoming signal and an earlier received signal which has been delayed for an interval corresponding to one television frame. The subtracter subtracts the attenuated difference signal from the incoming signal and develops an output in which noise is substantially reduced.
Claims14
A recursive filter for reducing noise in an incoming digitized, multi-bit television type signal having at least luminance components, comprising:
- subtracting means having first and second inputs and an output;
- means for applying the incoming television signal to the first input of said subtracting means without substantially attenuating the incoming signal;
- delay means coupled to the output of said subtracting means for developing a signal delayed by an interval substantially equal to a selected multiple of a television field interval;
- a motion detector receiving the incoming television signal and the delayed signal from said delay means for developing a difference signal representative of the differences between the incoming television signal and the delayed signal;
- an attenuator receiving the difference signal for selectively attenuating the same as a function of the amplitude of the difference signal;
- and
- means for coupling the attenuated difference signal to the second input of said subtracting means.
A recursive filter for reducing noise in an incoming digitized, multi-bit television signal having at least luminance components, comprising:
- subtracting means having first and second inputs and an output;
- means for applying the incoming unattenuated television signal to the first input of said subtracting means;
- a one frame storage device coupled to the output of said subtracting means for developing a frame-delayed video signal;
- a motion detector receiving the frame-delayed video signal from said frame storage device and the incoming television signal for generating a first output corresponding to the difference between the inputs to the difference detector and a second output corresponding to the absolute value of the first output;
- a coefficient generator responsive to said second output from said motion detector for generating coefficients indicative of a factor by which the difference signal is to be attenuated;
- a divider responsive to the difference signal and the coefficients for dividing the difference signal to provide an attenuated difference signal;
- and
- means for coupling the attenuated difference signal to the second input of said subtracting means.
Dependencies are inferred from the claim text.