KR960010189B1 - Image signal noise detection and elimination circuit - Google Patents

Abstract

a high-pass filter (1000) for filtering an input image signal to extract a high-pass component of the image signal; a subtracter (Sub) for subtracting the high-pass component from the image signal to extract a low-pass component of the image signal; a coring section (2000) for removing a minute level noise contained in the high-pass component from the high-pass filter; and an impulse noise remover (3000) for detecting and removing an impulse noise contained in the low-pass component by using horizontal and vertical correlation diagram of the noise picture information in one field of the low-pass component of the video signal.

Description

Noise Detection and Elimination Circuit of Image Signal

1 is an overall system diagram applied to the present invention.

2 is an example of the high-pass filter unit 1000 according to FIG. 1.

3A is a schematic diagram of the core ring part 2000 according to FIG. 1.

3B is an embodiment of the core ring part 2000 according to FIG. 1.

4 is an embodiment of the impulse noise removing unit 3000 according to FIG.

5 is a detailed view of the vertical image detection unit 100 of FIG.

6 is a detailed view of the first horizontal correlation detector 200 of FIG.

7 is a detailed view of the horizontal expansion unit 400 of FIG.

8 is a detailed view of a second horizontal correlation detector 300 of FIG. 4.

The present invention relates to a noise detection and removal circuit of a video signal for detecting and removing noise included in an original video signal applied to a video signal processing apparatus such as a television and a video tape recorder. The present invention relates to a noise detection and removal circuit of a video signal that can separate and remove noise contained in a high range and a low range of a signal appropriately.

In general, noise incorporated into televisions, video tape recorders, and the like is sensitive, and in the case of television receivers, it is particularly severely mixed in a weak electric field.

The noise seen in the video signal is considered as impulse noise, which is divided into white impulse noise and black impulse noise. In addition, the noise of the fine level included in the high band portion is a factor that seriously degrades the image quality.

Conventionally, in order to remove such noise, the input video signal has been taken by a constant window and simply averaged or replaced with a pixel having a moderate value or a moderate rank in the window using a median filter. However, this method has a problem in that the image quality of the edge portion is deteriorated because the high frequency component is processed together with the noise in the vertical component of the input image signal.

Accordingly, an object of the present invention is to provide a noise detection and removal circuit of an image signal capable of improving image quality in view of the above problems.

Another object of the present invention is to provide a noise detection and removal circuit of a video signal which can separate and remove noise contained in a high range and a low range of a video signal, respectively.

According to an aspect of the present invention for achieving the above object, the noise contained in the high range of the video signal is subjected to the coreling process, and the noise contained in the low range of the video signal is processed by detecting the vertical correlation and the horizontal correlation. It features.

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

FIG. 1 is an overall system diagram applied to the present invention, and includes a high pass filter 1000 for extracting a high pass component of an input video signal, and a low pass of the input video signal by subtracting the extracted high pass component from the input video signal. A subtractor (sub) for extracting a component, a core ring unit (2000) for removing noise included in a high frequency component of an image signal applied from the high pass filter unit (1000), and an image applied from the subtractor (Sub) An image from which noise is removed by adding an impulse noise removing unit 3000 to remove noise included in a low frequency component of the signal, an output signal of the core ring unit 2000 and an output signal of the impulse noise removing unit 3000. It consists of an adder (Add) for obtaining a signal.

2 is a diagram illustrating an example of the high pass filter 1000 according to FIG. 1. The pixel delay unit 1001 delays an input image signal by a pixel unit, and the input image signal and the pixel delay unit 1001. A subtractor Sub1 for subtracting the video signal delayed by the multiplier, a multiplier 1002 for multiplying the output of the subtractor Sub1 by one half, and a delayed output video signal of the multiplier 1002 by a pixel unit. Multiply the output of the subtractor Sub2 and the output of the subtractor Sub2 for subtracting the output video signal and the video signal delayed by the pixel delayer 1003 Multiplier 1004 for outputting the high-pass filtered video signal.

Here, it can be seen that the configuration of the high pass filter unit 1000 is made of a 2-tap high pass filter that satisfies Sin 뺑 =-(1-Z 뺑) 뺑 / 4.

3A shows a schematic diagram of the core ring unit 2000. FIG. 3A shows an input video signal as a graph A1, and 3b shows that the graph A1 is taken as an absolute value. (3c) shows that the signal of (3b) is applied to the coreling level (CL), (3d) shows that the coreing level (CL) of (3c) is subtracted, (3e Indicates that the signal of (3d) is restored to the core ring processing signal according to the polarity of the original signal 3a.

Therefore, it can be seen that the noise of the fine level included in the high frequency component can be removed by the above schematic. 3B is an exemplary embodiment in which the core ring part 2000 is implemented in hardware according to the outline of the diagram 3A. An input video signal such as (3a) input to the input terminal (b) is absolute-valued as shown in (3b) by an exclusive OR gate 2001.

The absolute valued video signal is latched by the latch 2002 and then input to one input terminal A of the adder 2004, and is equal to (3C) by the core ring level CL input to the latch 2003. The video signal is output.

The video signal of (3C) is latched out by the latch 2005 and applied to the first selector 2006, and the first selector 2006 is selected as shown in (3d) by the selection of the selection terminal S. Output video signal.

The video signal of 3d is applied to the second selector 2008 through a latch 2007, and the second selector 2008 adds the video signal of 3d according to the delay matching unit 2009 output. (2010). Therefore, the adder 2010 outputs an image signal as shown in (3e). Accordingly, the latch 2011 latches the video signal and outputs the image signal to the adder of FIG.

Cin used in the above (3B) means Carryin, and MSB and LSB were used to mean Most-Significant bit and Least-Significant bit, respectively.

FIG. 4 is a preferred embodiment of the impulse noise removing unit 3000 according to FIG. 1, and includes line delay units 17 and 19 for delaying a low frequency component image signal input to the input terminal A in units of lines. And a vertical line connected to the output points B and C of the line delay units 17 and 19 and the image signal output point A to detect a vertical correlation between the processed image signal and the vertical image signal. A correlation detector 100, a first horizontal correlation detector 200 connected to the output point B to detect horizontal correlation of the processing image signal line, and a noise pixel information connected to the output point B. And logic for detecting the center of the impulse noise by logically gating an output of the second horizontal correlation detector 300 and the vertical correlation detector 100 and the first horizontal correlation detector 200 for outputting noise center information. Means and horizontally output the logic means. Gating by horizontally extending the horizontal expansion unit 400 for discriminating pixels around the center of the noise, discriminating output of the horizontal expansion unit 400 and noise pixel pixel information of the second horizontal correlation detector 300. It consists of a multiplexer 500 for selectively removing noise in accordance with the information.

The first to third delayers 11, 13, and 15, which are not described in FIG. 2, are delayers for delaying the video signal during the noise elimination processing time, and the adder 21 and the multiplier 23 are up and down. For calculating the average value of the line pixels, the logic means corresponds to the AND gates 29 and 31 and the oragate 33.

FIG. 5 is a specific view showing a preferred embodiment of the vertical correlation detector 100 of FIG. FIG. 6 is a detailed diagram illustrating an embodiment of the second horizontal correlation detector 200 of FIG. 4.

FIG. 7 is a detailed diagram illustrating an embodiment of the horizontal extension 400 of FIG. 2. FIG. 8 is a detailed diagram illustrating an embodiment of the second horizontal correlation detector 300 of FIG. 2. Hereinafter, an embodiment of the reference operation will be described in detail with reference to FIGS. 1 to 8 based on the above-described configuration of the present invention.

First, the main gist of the present invention is to separate the input image signal into a high range and a low range, and then the noise of the fine level included in the high frequency component is processed by the core ring unit 2000, and the noise included in the low frequency component has a horizontal correlation with the vertical correlation. This is done using the diagram.

In FIG. 1, the high pass filter 1000 is configured as shown in FIG. 2 to extract a high pass component of an input image signal and output the extracted high pass component to the core ring unit 2000. In addition, the subtractor Sub subtracts the high frequency component from the input image signal, thereby outputting a low frequency component (low frequency component) of the video signal to the impulse noise removing unit 3000.

Accordingly, the core ring unit 2000 outputs an image signal such as (3e) in (3A) by the configuration as shown in (3B), so that it can be seen that the fine level noise included in the high frequency component is removed.

On the other hand, the impulse noise removing unit 3000 has a configuration as shown in FIG. 4, and in FIG. 4, the multiplexer 500 selectively removes the impulse noise according to the selection of the selection terminal S. Referring to FIG. In other words, if it is determined as impulse noise, the average value of upper and lower humans is output to remove noise. If it is determined that the noise is not noise, the input video signal is output as it is. The noise detection information of the selection stage S is information generated by detecting the vertical correlation and the horizontal correlation of the input video signal.

4 to 8, the vertical correlation detector 100 is configured to output the current input video signal from the output points A, B, and C, a horizontal line delayed video signal, and the like. The vertical correlation is detected by inputting the horizontal video delayed video signals. If the output point B is defined as a processing point, the first horizontal line delayed video signal becomes a processing video signal, and the current input video signal and the two horizontal line delayed video signals become upper and lower video signals.

Referring to FIG. 5 to describe the vertical correlation detector 100, if the input image signal is noise, the pixels of the processed image signal and the upper lines are arranged on the upper line with the pixels of the processed image signal. The difference from the pixel is detected. Subsequently, the detection value is compared with a preset reference value Th1 to determine whether white impulse noise or black impulse noise is generated.

Accordingly, the AND gate 109 determines whether or not black impulse noise is output to the output line G ', and the AND gate 110 determines whether or not white impulse noise is output to the output line G. Here, the comparators 105 and 106 output high when the output of the subtractors 101 and 102 are greater than the reference value Th1, and the comparators 107 and 108 multiply the output of the subtractor 101 and 102 by the multiplier 103 and 104 than the reference value Th1. If the multiplied value is large, output high.

In addition, the detailed configuration of the first horizontal correlation detector 200 is shown in FIG. FIG. 6 detects a difference between pixels of the processed video signal and two pixels before and after the input image signal is horizontally uncorrelated, and compares it with a preset reference value Th2.

The comparators 407 and 408 output high when the output of the subtractors 403 and 404 are larger than the reference value Th2, and the comparators 409 and 410 multiply the outputs of the subtractor 403 and 404 as the multipliers 405 and 406 than the reference value Th2. High if the multiplied value is large. The high means that there is noise, and the AND gate 412 outputs the presence of the white impulse noise to the output line (H), and the AND gate 411 outputs the presence or absence of black impulse noise to the output line (H '). )

On the other hand, the second horizontal correlation detector 300 outputs noise pixel information and noise center information. The detailed configuration of the second horizontal correlation detection unit 300 is a subtractor 503 and 504, in order to obtain the noise center information in FIG. After obtaining, it is output to the first to second absolute values 506 and 506.

The noise pixel information is used to detect whether the pixel is within a noise width, and the outputs of the subtractors 503 and 504 are processed by the first to second absolute values 506 and 506, the comparators 508 and 509, and the AND gate 510. Therefore, if high is present in the output line K, it is determined that the pixel is within the noise width.

Accordingly, in FIG. 4, the logic means, that is, the AND gates 29 and 31 and the oragate 33, logically gate the outputs of the vertical correlation detector 100 and the first horizontal phase and the detector 200 to generate impulse noise. The detected value of the center is output to the output line (I). That is, when the output line G of the vertical correlation detector 100 and the output line H of the first horizontal correlation detector 200 are gated by the AND gate 29, it is determined to be white impulse noise. When the output line G 'of the vertical correlation detector 100 and the output of the output line H' of the first horizontal correlation detector 200 are gated by the AND gate 31, it is determined that the signal is black impulse noise. do.

When the output of the AND gates 29 and 31 are gated by the oragate 33 and high is present in the output I, white impulse noise or black impulse noise is generated.

The output of the output line I is input to the horizontal expansion unit 400, which horizontally expands the output of the logic means to determine pixels around the center of the noise. A detailed configuration of one embodiment of the horizontal expansion unit 400 is shown in FIG. The pixel exciters 601 to 604 and oragate 605 of FIG. 7 extend the output of the logic means horizontally to determine the pixels around the center of the noise.

The output line J of the horizontal expansion unit 400 is connected to one side input of the AND gate 35 of FIG. 4. The AND gate 35 gates the output of the output line K of the horizontal expansion unit 400 and the second horizontal correlation detector 300, and selects the multiplexer 500 through the output line L. Output as (S). The gating information of the AND gate 35 is information about the noise pixel information and the discrimination output of the horizontal expansion unit 400. Therefore, if the selection stage S1 of the multiplexer 500 is lower, the output of the multiplier 23 that calculates the average value of the upper and lower pixels is selected and output to the output terminal A '.

Therefore, the adder of FIG. 1 adds the output of the impulse noise removing unit 3000 and the output of the core ring unit 2000 and outputs the noise-reduced output image signal to the output terminal, thereby improving image quality. Done.

In the embodiment of the present invention has been presented a specific hardware, detailed configuration will be understood that various changes and modifications can be made by those skilled in the art.

As described above, the present invention has an advantage in that noise included in a high range and a low range of an image signal can be appropriately removed, thereby improving image quality.

Claims (6)

A circuit for detecting and removing noise of a video signal transmitted from a transmission system, the circuit comprising: a high pass filter unit for high pass filtering an input video signal to extract high frequency components of the video signal, and the extracted video signal from the input video signal A subtractor for extracting low frequency components of the input video signal by subtracting a high frequency component of the high frequency component and a high frequency component of the high frequency component to remove fine level noise included in the high frequency component And an impulse noise removing unit for detecting and removing the impulse noise included in the low frequency component by using the vertical and horizontal correlation diagrams of noise image information in one field as the low frequency component of the input video signal applied from the subtractor. Noise detection and removal circuit of the video signal, characterized in that. 2. The apparatus of claim 1, further comprising: a pixel delay unit configured to delay the input video signal by a pixel unit, a subtractor for subtracting the input video signal and a video signal delayed by the pixel delay unit, and outputting the subtractor; A multiplier for outputting by multiplying by 1/2, a pixel retarder for delaying the output video signal of the multiplier by a pixel unit, a subtractor for subtracting and outputting the output video signal and a video signal delayed by the pixel delayer, and And a multiplier for outputting a high-pass filtered video signal by multiplying the output by -1/2. The display device of claim 1, wherein the impulse noise canceling unit is connected to a line delay unit for delaying a video signal of a low frequency component input to an input terminal in units of lines, and connected to an output point of the line delay unit and the video signal input terminal. A vertical correlation detector detecting a vertical correlation with an image signal of a line, a first horizontal correlation detector connected to the output point to detect a horizontal correlation of the processing image signal line, and noise pixel information connected to the output point And logic means for detecting a center of impulse noise by logically gating an output of the first horizontal correlation detector for outputting noise center information, the output of the vertical correlation detector and the first horizontal correlation detector, and horizontally outputting the output of the logic means. A horizontal expansion unit for discriminating and outputting pixels around a center of noise, and a discriminating output of the horizontal expansion unit Group second horizontal correlation detecting a noise pixel information according to the gating end a gating information selectively noise detection of the video signal, characterized by consisting of a multiplexer for removing noise and removal of the circuit. A noise detection and removal circuit for separating and removing noise of a video signal into a high pass and a low pass, comprising: a high pass filter for extracting high pass components of the video signal by high pass filtering an input video signal; A subtractor for extracting the low pass component of the input video signal by subtracting the high pass component of the received video signal, and the high frequency component of the video signal applied from the high pass filter unit to remove fine level noise included in the high pass component An impulse noise removal unit for detecting and removing impulse noise included in the low pass component using a vertical correlation and a horizontal correlation diagram of the noise image information in one field as a core ring unit and a low pass component of the input image signal applied from the subtractor And an output signal of the core ring unit and an output signal of the impulse noise removing unit. Acid by the noise detection of the video signal characterized in that it consists of an adder which outputs a video signal which noise is removed, and removal circuit. 5. The apparatus of claim 4, further comprising: a pixel delay unit configured to delay the input video signal by a pixel unit, a subtractor for subtracting the input video signal and a video signal delayed by the pixel delay unit, and outputting the subtractor; A multiplier for outputting by multiplying by 1/2, a pixel retarder for delaying the output video signal of the multiplier by a pixel unit, a subtractor for subtracting and outputting the output video signal and a video signal delayed by the pixel delayer, and And a multiplier for outputting a high-pass filtered video signal by multiplying the output by -1/2. 6. The apparatus of claim 5, wherein the low-frequency component input to the input terminal of the impulse noise canceling unit is connected to a line delay unit for delaying an image signal in units of lines, an output point of the line delay unit, and an image signal input terminal. A vertical correlation detector detecting vertical correlation with the image signal of the line, a first horizontal correlation detector connected to the output point to detect and output a horizontal correlation of the processing image signal line, and a noise pixel connected to the output point A second horizontal correlation detector for detecting and outputting a horizontal correlation between information and noise center information, a logic gate for detecting the center of impulse noise by logically gating outputs of the vertical correlation detector and the first horizontal correlation detector; Horizontal extension to discriminate and output pixels around the center of noise by horizontally extending the output of the logic gate And a multiplexer which selectively removes noise in accordance with the gating information obtained by gating the discriminating output of the horizontal expansion unit and the noise pixel information of the second horizontal correlation detection unit.