KR930008692Y1 - Video signal noise reducing circuit by using delaying and averaging filter - Google Patents

Abstract

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Description

Image Signal Noise Reduction Circuit Using Delay Average Filter

1 is a block diagram of a delay average filter according to the present invention.

2 is an operation waveform diagram of a delay average filter according to the present invention.

3 is a specific embodiment of the present invention

The present invention relates to a noise reduction circuit for reducing noise in a video signal processing circuit of a forward scan type video device.

In a video tape recorder (hereinafter referred to as a VTR), when a tape is in a bad state, noise occurs in a video signal.

Also in television, noise is generated on the screen by the influence of intermodulation and the like. In this case, the noise canceling circuit can be configured by using a high correlation between the signals between the horizontal frequency signals of the video signals. In general, a noise reduction circuit is formed inside a VRT or a TV to remove noise of a video signal. Since noise is an inherently strong high frequency component, it detects high frequency of more than one band of the video signal and operates the noise canceling circuit.

However, the video signal in the dense part of the picture elements or in the parts with varying contrast is a high frequency component corresponding to noise. Therefore, the noise canceling circuit removes not only the noise but also the signal in the dense part of the screen configuration or the part in which the change of contrast is minute.

In addition, the noise canceling circuit has become an essential component of the image signal processing circuit.

That is, the noise is always forcibly removed by assuming that noise is always included in the video signal. For this reason, the signal is always removed even at a portion where a high frequency component is dense in the video signal or where a change in contrast is minute.

Accordingly, an object of the present invention is to provide a device capable of changing the reduction rate in reducing noise included in a video signal and simultaneously reducing noise included in a user's selection.

In order to achieve the above object, in the present invention, a delay means for delaying a horizontal video signal for a predetermined period by using a high correlation between adjacent horizontal video signals and a horizontal video signal delayed through the delay means and the original An adder capable of adding a horizontal video signal and an attenuator for attenuating the output of the adder constitute a delay average filter, and use the delay average filter to perform noise attenuation for one horizontal scan period or one feed period, respectively. A first delay average filter and a second delay average filter are configured, and a first switching unit and a second switching unit for connecting the two delay average filters described above are included.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, FIG. 1 and FIG. 2 show the operation of the delay average filter used in the present invention.

In the video signal, when the n + 1 th signal Hn + 1 of the horizontal scan line has a noise component of magnitude y, the correlation between the n th signal Hn of the horizontal scan line and the adjacent horizontal scan line Hn + 2 after 1 field is high. When Hn is delayed for one horizontal scanning period (hereinafter referred to as 1H) and added to Hn + 1, as shown in FIG. 2B, a double-sized video signal is obtained and the magnitude of noise remains as it is.

If this is attenuated by a half through an attenuator, a noise signal halved with the original video signal is obtained as shown in FIG. 2C. In addition, if the horizontal video signal having the noise component attenuated by 1/2 times is delayed by one feed period and the addition and attenuation operations are performed as described above, a horizontal video signal having the noise signal attenuated by 1/4 can be obtained. In this case, the noise component is called a delay average filter in the sense that it is 1/2 or 1/4 times the original value.

3 shows a specific embodiment of the present invention.

In the circuit composed of the switching sections 10 and 30 and the delay average filters 20 and 40, the video signal separated from the input video signal is connected to the switching section 11 of the first switching section 10 and the fixed terminal on one side. (12) is connected to the output terminal and the other fixed terminal 13 belongs to the input of the first delay average filter 20, the output of the first delay average filter 20, the switching section of the second switching switch 30 (31), one fixed terminal 32 is connected to the output terminal, and the output of the second delay average filter 40 is connected to the output terminal.

This invention by the structure mentioned above is demonstrated in detail, for example.

If it is determined that there is a lot of noise on the screen while the VTR or the TV is in operation, the user selects the fixed terminal connected to the first delay average filter by the first switching switch 10, and at this time, horizontal scanning as shown in FIG. A video signal in which noise between signals is reduced is obtained. If it is determined that there is a lot of noise even in this state, the second switching average 30 can select the second delay average filter 40, and can perform a reduced operation with the adjacent horizontal scanning signal between one feed. In the noise reduction operation between the feed scans, the principle is the same as the noise reduction operation between the adjacent horizontal scan lines. However, in the sequential scanning method, the intermediate position of Hn and Hn + 1 after the horizontal scanning signal Hn and one vertical scanning period. Since there is a difference in the one-duration period between the horizontal scanning components scanned in, the delay time of the second delay average filter 40 is set to a time corresponding to one-cycle period.

Claims (4)

In the video signal processing of a sequential scan type video device, a delay means (1) capable of delaying a horizontal video signal for a predetermined period, and a horizontal video signal delayed through the delay means and a horizontal video signal currently inputted are added. And a delay average filter configured as an attenuator (3) for attenuating the output of said adder. The delay average filter according to claim 1, wherein the adder (2) and the attenuator (3) allow the magnitude of the image signal to be the same and the noise level to be reduced by half when comparing the input image signal with the output image signal. And a delay average filter for determining a characteristic of the video signal noise reduction circuit. A first delay average filter 20 and a second delay average filter 40 which perform noise reduction operations between one horizontal scanning period or one gain period, respectively, using the delay average filter of claim 1 are constructed. And a second switching unit (30) and a second switching unit (30) for connecting two delay average filters. 4. The apparatus of claim 3, further comprising a first delay average filter 20 having a delay time corresponding to one horizontal scanning period of the video signal and a second delay average filter 40 corresponding to one feed period of the video signal. The video signal noise reduction circuit, characterized in that.