Digital video signal noise-reduction apparatus with high pass and low pass filter

Claim 2

A noise-reduction apparatus for reducing noise in a digital video signal having a high-frequency component and a low-frequency component, the apparatus comprising: high-frequency component extracting means for receiving the digital video signal and for extracting the high-frequency component thereof; two-frame difference detecting means for receiving the high-frequency component extracted by said high-frequency component extracting means and for detecting a two-frame difference signal representing a difference between a signal and a two-frame delayed signal; first elimination signal generating means, for generating a first elimination signal corresponding to the two-frame difference signal detected by said two-frame difference detecting means; low-frequency component extracting means for receiving the digital video signal and for extracting the low-frequency component thereof; frame difference detecting means for receiving the low-frequency component extracted by the low-frequency component extracting means and for detecting a frame difference signal representing a difference between a signal and a one-frame delayed signal; second elimination signal generating means, for generating a second elimination signal corresponding to the frame difference signal detected by said frame difference detecting means; and noise eliminating means for eliminating the noise from the digital video signal in accordance with the first elimination signal generated by said first elimination signal generating means and the second elimination signal generated by said second elimination signal generating means.

Claim 3

The noise-reduction apparatus according to claim 1, further including two-frame delay means for delaying the high-frequency component by two frames, whereby said two-frame difference detecting means subtracts from the high-frequency component a two-frame delayed high-frequency component which is delayed by said two-frame delay means for detecting the two-frame difference signal.

Claim 4

The noise-reduction apparatus according to claim 1, further including one-frame delay means for delaying the low-frequency component by one frame, whereby said frame difference detecting means subtracts from the low-frequency component a one-frame delayed low-frequency component which is delayed by said one-frame delay means for detecting the one-frame difference signal.

Claim 5

The noise-reduction apparatus according to claim 1, wherein said noise eliminating means includes means for subtracting from the high-frequency component the first elimination signal generated by said fist elimination signal generating means and for outputting a first subtraction signal.

Claim 6

The noise-reduction apparatus according to claim 1, wherein said noise eliminating means includes means for subtracting from the low-frequency component the second elimination signal generated by said second elimination signal generating means and for outputting a second subtraction signal.

Claim 7

The noise-reduction apparatus according to claim 1, wherein said noise eliminating means further includes means for subtracting from the high-frequency component the first elimination signal and for generating a first subtraction signal, means for subtracting from the low-frequency component the second elimination signal and for generating a second subtraction signal, and means for additively combining the first and second subtraction signals.

Claim 8

A noise-reduction apparatus for reducing noise in a digital video signal having a high-frequency component and a low-frequency component, the apparatus comprising: two-frame difference detecting means for receiving the digital video signal and for detecting a two-frame difference signal representing a difference between a signal and a two-frame delayed signal; high-frequency component extracting means connected to extract a high-frequency component of the two-frame difference signal detected by said two-frame difference detecting means; first elimination signal generating means, for generating a first elimination signal corresponding to the high-frequency component extracted by said high-frequency component extracting means; frame difference detecting means for receiving the digital video signal and for detecting a frame difference signal representing a difference between a signal and a one-frame delayed signal; low-frequency component extracting means for extracting a low-frequency component of the frame difference signal detected by said frame difference detecting means; second elimination signal generating means, for generating a second elimination signal corresponding to the low-frequency component extracted by said low-frequency component extracting means; and noise eliminating means for eliminating the noise from the digital video signal, in accordance with the first elimination signal generated by the first elimination signal generating means and the second elimination signal generated by the second elimination signal generating means.

Claim 9

A noise-reduction apparatus for reducing noise in a digital video signal having a high-frequency component and a low-frequency component, the apparatus comprising: two-frame difference detecting means for receiving the digital video signal and for detecting a two-frame difference signal representing a difference between a signal and a two-frame delayed signal; high-frequency component extracting means connected to extract a high-frequency component of the two-frame difference signal detected by said two-frame difference detecting means; first elimination signal generating means, for generating a first elimination signal corresponding to the high-frequency component extracted by said high-frequency component extracting means; frame difference detecting means for receiving the digital video signal and for detecting a frame difference signal representing a difference between a signal and a one-frame delayed signal; low-frequency component extracting means for extracting a low-frequency component of the frame difference signal detected by said frame difference detecting means; second elimination signal generating means, for generating a second elimination signal corresponding to the low-frequency component extracted by said low-frequency component extracting means; and noise eliminating means for eliminating the noise from the digital video signal, in accordance with the first elimination signal generated by the first elimination signal generating means and the second elimination signal generated by the second elimination signal generating means.

Claim 10

The noise-reduction apparatus according to claim 7, further including two-frame delay means for delaying said digital video signal, whereby said two-frame difference detecting means subtracts from the digital video signal a two-frame delayed digital video signal which is delayed by said two-frame delay means for detecting the two-frame difference signal.

Claim 11

The noise-reduction apparatus according to claim 7, further including one-frame delay means for delaying the digital video signal by one frame, whereby said frame difference detecting means subtracts from the digital video signal a one-frame delayed digital video signal which is delayed by said one-frame delay means for detecting the frame difference signal.

Claim 12

The noise-reduction apparatus according to claim 7, further including two-frame delay means for delaying the digital video signal by two frames, and one-frame delay means for delaying the digital video signal by one frame.

Claim 13

The noise-reduction apparatus according to claim 7, wherein said noise eliminating means includes first subtracting means for subtracting from the digital video signal the first elimination signal generated by said first elimination signal generating means, and second subtracting means for subtracting from the digital video signal the second elimination signal generated by said second elimination signal generating means.

Claim 14

A noise-reduction apparatus for reducing noise in a digital video signal before being input to a Y/C separation circuit, the noise-reduction apparatus comprising: first means, responsive to the digital video signal, for generating a first noise-reducing signal for correcting a high-frequency portion of said digital video signal, said first means comprising: means for extracting said high-frequency portion from said digital video signal, means for generating a two-frame difference signal representing a difference between said high-frequency portion and an externally-generated two-frame delayed high-frequency portion of a corresponding noise-reduced digital video signal, and means for generating said first noise-reducing signal in response to said high-frequency portion and said two-frame difference signal; second means, responsive to the digital video signal, for generating a second noise-reducing signal for correcting a low-frequency portion of said digital video signal, said second means comprising: means for extracting said low-frequency portion from said digital video signal, means for detecting a single-frame difference signal representing a difference between said low-frequency portion and an externally-generated single-frame delayed low-frequency portion of a corresponding noise-reduced digital video signal, and means for generating said second noise-reducing signal in response to said low-frequency portion and said single-frame difference signal; and means for generating a noise-reduced digital video signal, responsive to said first and second noise-reducing signals, for being input to said Y/C separation circuit.

Claim 15

A noise-reduction apparatus for reducing noise in a digital video signal before being input to a Y/C separation circuit, the noise-reduction apparatus comprising: first means, responsive to the digital video signal, for generating a first noise-reducing signal for correcting a high-frequency portion of said digital video signal, said first means comprising: means for extracting said high-frequency portion from said digital video signal, means for generating a two-frame difference signal representing a difference between said high-frequency portion and an externally-generated two-frame delayed high-frequency portion of a corresponding noise-reduced digital video signal, and means for generating said first noise-reducing signal in response to said high-frequency portion and said two-frame difference signal; second means, responsive to the digital video signal, for generating a second noise-reducing signal for correcting a low-frequency portion of said digital video signal, said second means comprising: means for extracting said low-frequency portion from said digital video signal, means for detecting a single-frame difference signal representing a difference between said low-frequency portion and an externally-generated single-frame delayed low-frequency portion of a corresponding noise-reduced digital video signal, and means for generating said second noise-reducing signal in response to said low-frequency portion and said single-frame difference signal; and means for generating a noise-reduced digital video signal, responsive to said first and second noise-reducing signals, for being input to said Y/C separation circuit.

Claim 16

A noise-reduction apparatus recited in claim 12, wherein said means for generating a noise-reduced digital video signal comprises: means for generating a high-frequency portion of said noise-reduced digital video signal in response to said high-frequency portion of said digital video signal and said first noise-reducing signal; means for generating a low-frequency portion of said noise-reduced digital video signal in response to said low-frequency portion of said digital video signal and said second noise-reducing signal; and means for generating said noise-reduced digital video signal in response to said low and high-frequency portions of said noise-reduced digital video signal.

Claim 17

A noise-reduction apparatus as recited in claim 13, further comprising: means for delaying by two frames said high-frequency portion of said noise-reduced digital video signal and outputting said externally-generated two-frame delayed high-frequency portion of said corresponding noise-reduced digital video signal; and means for delaying by a single frame said low-frequency portion of said noise-reduced digital video signal and outputting said externally-generated single-frame delayed low-frequency portion of said corresponding noise-reduced digital video signal.

Claim 18

A noise-reduction apparatus for reducing noise in a digital video signal before being input to a Y/C separation circuit, the noise-reduction apparatus comprising: first means, responsive to the digital video signal, for generating a first noise-reducing signal for correcting a high-frequency portion of said digital video signal, said first means comprising: means for detecting a two-frame difference signal representing a difference between said digital video signal and an externally-generated two-frame delayed noise-reduced digital video signal, means for extracting a high-frequency portion from said two-frame difference signal, and means for generating said first noise-reducing signal in response to said high-frequency portion of said two-frame difference signal; second means, responsive to the digital video signal, for generating a second noise-reducing signal for correcting a low-frequency portion of said digital video signal, said second means comprising: means for detecting a single-frame difference signal representing a difference between said digital video signal and an externally-generated single-frame delayed noise-reduced digital video signal, means for extracting a low-frequency portion from said single-frame difference signal, and means for generating said second noise-reducing signal in response to said low-frequency portion of said single-frame difference signal; and means for generating a noise-reduced digital video signal, responsive to said first and second noise-reducing signals, for being input to said Y/C separation circuit, said means for generating a noise-reduced digital video signal correcting said digital video signal in accordance with said first and second noise-reducing signals.

Claim 19

A noise-reduction apparatus for reducing noise in a digital video signal before being input to a Y/C separation circuit, the noise-reduction apparatus comprising: first means, responsive to the digital video signal, for generating a first noise-reducing signal for correcting a high-frequency portion of said digital video signal, said first means comprising: means for detecting a two-frame difference signal representing a difference between said digital video signal and an externally-generated two-frame delayed noise-reduced digital video signal, means for extracting a high-frequency portion from said two-frame difference signal, and means for generating said first noise-reducing signal in response to said high-frequency portion of said two-frame difference signal; second means, responsive to the digital video signal, for generating a second noise-reducing signal for correcting a low-frequency portion of said digital video signal, said second means comprising: means for detecting a single-frame difference signal representing a difference between said digital video signal and an externally-generated single-frame delayed noise-reduced digital video signal, means for extracting a low-frequency portion from said single-frame difference signal, and means for generating said second noise-reducing signal in response to said low-frequency portion of said single-frame difference signal; and means for generating a noise-reduced digital video signal, responsive to said first and second noise-reducing signals, for being input to said Y/C separation circuit, said means for generating a noise-reduced digital video signal correcting said digital video signal in accordance with said first and second noise-reducing signals.

Claim 20

A noise-reduction apparatus as recited in claim 15, further comprising: means for delaying said noise-reduced digital video signal and outputting said externally-generated single-frame delayed noise-reduced digital video signal; and means for delaying said externally-generated single-frame delayed noise-reduced digital video signal and outputting said externally-generated two-frame delayed noise-reduced digital video signal.