KR19990021135A - Noise canceling method and noise canceling circuit for performing the same - Google Patents

Abstract

Disclosed are a noise removing method for improving the image quality of a television by sensing the energy of a high frequency region of a video signal and suppressing noise appearing on the television screen according to the detected energy level, and a noise removing circuit for performing the same. Subtracts the low-pass filtered video signal from the video signal, receives the subtracted signal, and detects the energy or noise level of the high frequency region in the energy detector and amplifies the amplifier in the range of 0≤α≤1 according to the energy level. By suppressing and amplifying by adjusting the ratio α value, an amplified signal that suppresses noise of a high frequency component is generated. At this time, if the energy or noise level detected by the energy detector is large, α ≒ 0, and if it is medium, α = 1/2, and if small, α = 1. The gain α of the amplifier is adjusted according to the energy or noise level sensed by the energy detector to perform the function of the amplifier, and then the signal of which the high frequency component of the signal is suppressed and amplified and the contour corrected low frequency component of the signal through the amplifier. Compositing improves the image quality of the TV by suppressing noise appearing on the TV screen.

Description

Noise canceling method and noise canceling circuit for performing the same

The present invention relates to a noise removing method for suppressing noise of a video signal and a noise removing circuit for performing the same. More particularly, the present invention relates to noise suppression to improve TV quality by suppressing noise appearing on a television screen. The present invention relates to a noise removing method for removing the noise and a noise removing circuit for performing the same.

In image processing systems such as televisions or video recorders, one of the important problems is the reproduction of clean images without noise. Normally, screen images provided from broadcasting stations or video tape production companies are likely to introduce unnecessary noise due to image transmission channels or repeated copying. In addition, noise may be introduced into the image information signal during operation of the image signal processing system, and furthermore, the image is also affected by a weak electromagnetic wave while receiving the television image signal.

In general, noise is classified into impulse noise and line noise, and the impulse noise is further classified into white noise and black noise. Such noise may occur even when included in an image source or when a low quality film is used in an image processing system, and various measures must be considered to effectively reduce or suppress noise components.

Therefore, when a lot of noise of a high frequency component exists in a television signal, there exists a problem in the TV image quality when watching, and the noise of the high range part of a television signal is hard to remove.

Accordingly, the present invention has been made in view of the above, and a first object of the present invention is to provide a noise removing method for suppressing a noise level on a television screen to improve TV quality.

It is a second object of the present invention to provide a noise canceling circuit suitable for performing the above method.

1 is a circuit diagram illustrating a noise removing circuit according to an exemplary embodiment of the present invention.

2A to 2F are waveform diagrams for explaining the noise removing operation of each part of the noise removing circuit shown in FIG. 1.

FIG. 3 is a flowchart for describing a method for removing noise in the apparatus shown in FIG. 1.

Explanation of symbols for main parts of the drawings

110: low pass filter 210: first delay

220: contour correction circuit 310: energy detector (Energy Detector)

320: second delay 330: amplifier of amplification factor α

120: subtractor 410: summer

In order to carry out the first object of the present invention described above, the present invention provides a method for generating a low-pass filtered video signal and a low-pass filtered video signal from a video signal. (b) receiving the subtracted signal and outputting a signal obtained by suppressing and amplifying a high frequency portion of noise; (c) receiving the low-pass filtered video signal and outputting a video signal of a contour-corrected low pass component; And (d) summing the signal from which the high frequency portion of the noise is suppressed and amplified with the video signal of the contour corrected low frequency component to output a video signal of the low frequency component whose noise is suppressed to correct the contour. Provide a method.

In order to achieve the second object of the present invention, the present invention provides a low-pass subtraction unit for outputting a low-pass filtered video signal and a low-pass filtered video signal subtracted from the video signal; A delay contour correction unit configured to receive the low-pass filtered video signal and output a video signal of a contour-corrected low pass component; A delay amplifier configured to receive the subtracted signal and output a signal obtained by suppressing and amplifying noise of a high frequency component; And synthesizing the suppressed amplified signal of the high frequency portion and the video signal of the contour-corrected low-pass component to synthesize the video signal of the contour-corrected low-pass component by suppressing noise and outputting a video signal of the contour-corrected low-frequency component by suppressing the noise. A noise canceling circuit comprising a summation section is provided.

According to the present invention, the noise of the high frequency part is suppressed and the video signal of the low frequency component whose contour is corrected is output, and the TV picture quality can be improved by suppressing the noise of the high frequency component on the television screen.

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

1 is a circuit diagram showing a noise removing circuit for suppressing noise of a television signal according to an embodiment of the present invention.

Referring to FIG. 1, a noise reduction circuit of a television signal according to an embodiment of the present invention includes a low pass subtraction unit 100, a delay contour correction unit 200, a delay amplification unit 300, and a summation unit 400. do.

The low pass subtractor 100 is composed of a low pass filter 110 and a subtractor 120.

The low pass filter 110 receives the television video signal 102 input through the input terminal 101 and performs low pass filtering on the low pass filtered signal 111 to the subtractor 120 and the delay contour correction unit 200. Output

The subtractor 120 subtracts the low-pass filtered video signal 111 from the video signal 102 and outputs the subtracted signal 121 to the delay amplifier 300.

The delay contour correction unit 200 includes a first delay unit 210 and a contour correction circuit 220.

The first delay unit 210 receives and delays the low-pass filtered signal 111 to provide the first delayed signal 211 to the contour correction circuit 220.

The contour correction circuit 220 receives the first delayed signal 211 and compensates an edge to output the contour corrected video signal 221 of the low frequency component to the adder 400.

The energy amplifier 310 of the delay amplifier 300 is composed of a second delay amplifier 320, an amplifier 330.

The energy detector 310 receives the subtracted signal 121 and detects an energy or noise level in the high range of the signal, and controls a control signal 311 for adjusting the gain α of the amplifier 330 according to the level of the signal. To provide. The gain α of the amplifier 330 is represented as follows depending on the energy level.

0 ≤ α ≤ 1

In response to the input of the subtracted signal, the high frequency portion of the signal sensed by the energy detector 310 senses an energy or noise level, and adjusts a gain α value of an amplifier present in a range of 0 ≦ α ≦ 1 according to the noise level. More specifically, if the detected noise level is large, the gain α has a value close to zero. If the noise level has a medium value, the gain α has a value of 1/2. If the noise level is small, the gain α has a value of 1. It will be shown in Table 1 below.

TABLE 1

Therefore, the control signal 311 for adjusting the amplification factor α by sensing the energy or noise level in the energy detector 310 by receiving the input of the subtracted signal 121 is input to the amplifier 330 and the high frequency component of the signal. Suppresses and amplifies the noise, and receives the subtracted signal 121 and delays the second delay 320 to provide the delayed signal 321 to the amplifier 330 to provide a high frequency component in the amplifier 330. Noise is reduced and amplified by the gain (amplification factor) of the amplifier to provide the output signal 331 whose noise is suppressed to the summing unit 400.

The adder 400 includes only the adder 410. The adder 400 receives the suppressed amplified signal 331 and the contour-corrected low-frequency component video signal 221 and synthesizes the synthesizer 410 to suppress noise. The video signal 411 of the contour-corrected low pass component is output.

2A to 2F are waveform diagrams for explaining a noise removing operation in each part of the noise removing circuit of FIG. 1 which is an embodiment of the present invention. FIG. 3 is a flowchart for briefly explaining a method for removing noise according to an embodiment of the present invention performed in the apparatus shown in FIG. 1.

The television video signal 102 inputted from the input terminal 101 as shown in FIG. 2A is input to the low pass filter 110 and the subtractor 120 and the low pass filtered video signal 111 as shown in FIG. It is provided to the one delay unit 210 and the subtractor 120 (step S1).

The subtractor 120 subtracts the low pass filtered video signal 111 from the input video signal 102 and subtracts the subtracted signal 121 from the second delay unit 320 and the energy detector as shown in FIG. 310) (step S2).

The subtracted signal 121 is input to the energy detector 310 to sense the energy or noise level in the high frequency region to adjust the α value of the amplifier 330 (step S3).

The subtracted signal 121 is also input to the second delay unit 320 so that the delayed signal 321 is provided to the amplifier 330 (step S4).

The amplifier 330 receives the delayed signal 321 and provides, to the adder 410, a signal 331 whose noise of the high range part of the signal is suppressed and amplified as shown in FIG. S5).

The low-pass filtered video signal 111 is input to the first delay unit 210 to provide a delayed low-pass video signal 211 to the contour correction circuit 220 (step S6).

The delayed low pass video signal 211 is input to the contour correction circuit 220 and a video signal 221 of the contour corrected low pass component is provided to the summer 410 as shown in FIG. 2C (step S7).

The suppressed amplified signal 331 and the contour-corrected low frequency component video signal 221 are input to the summer 410 and summed in the summer 410 (step S8). The summed signal 411 is output to the outside via the output terminal 103 as a video signal of a low pass component whose noise is suppressed and contour-corrected as shown in Fig. 2D (step S9).

As a result, the low-pass filtered video signal is subtracted from the input video signal, and the energy detector detects the energy or noise level in the high frequency region by receiving the input of the subtracted signal and transmits 0 ≤ α ≤ 1 to the amplifier according to the energy level. By suppressing and amplifying by adjusting the α value present in the range, an amplified signal that suppresses noise of a high frequency component is generated. At this time, if the energy or noise level detected by the energy detector is large, α ≒ 0, and if it is medium, α = 1/2, and if small, α = 1.

Combining the suppressed amplified signal and the low pass filtered contour corrected video signal via the energy detector suppresses noise appearing on the television screen, thereby improving the image quality of the television.

As described above, according to the noise canceling circuit in which the method and configuration for suppressing the noise according to the present invention are presented, the low-pass filtered signal is subtracted from the signal of the television to suppress the noise appearing on the television screen, and this subtraction is performed. The energy detector detects the energy or noise level of the high range of the signal and suppresses and amplifies the α value of the amplifier according to the energy level. By outputting a television signal in which the noise of the component is suppressed, an effect of improving the TV quality is obtained.

Although this invention was demonstrated concretely by the said Example, this invention is not restrict | limited by this, A deformation | transformation and improvement are possible within the normal knowledge of a person skilled in the art.

Claims (9)

(a) outputting a low-pass filtered video signal and a signal subtracted from the video signal by the low-pass filtered video signal; (b) receiving the subtracted signal and outputting a signal obtained by suppressing and amplifying a high frequency portion of noise; (c) receiving the low-pass filtered video signal and outputting a video signal of a contour-corrected low pass component; And and (b) summing the high-frequency portion of the noise into the suppressed-amplified signal and the video signal of the contour-corrected low-pass component to output a video signal of the low-pass component, which has been suppressed by noise, to correct the contour. . The method of claim 1, wherein step (a) comprises: (a-1) low pass filtering the video signal to output the low pass filtered video signal; And (a-2) subtracting the low-pass filtered video signal from the video signal and outputting the subtracted signal. The method of claim 1, wherein step (b) comprises: (b-1) receiving and delaying the subtracted signal to provide a second delayed signal; (b-2) receiving the subtracted signal and detecting a noise level to determine an amplification factor α; And and (b-3) reducing and amplifying the second delayed signal at the amplification factor α to output a signal in which the high frequency portion of the noise is suppressed and amplified. The method of claim 1, wherein step (c) comprises: (c-1) delaying the low-pass filtered video signal to generate a first delayed signal; And and (c-2) edge compensating the first delayed signal to output a video signal of the contour-corrected low pass component. A low pass subtraction unit 100 for outputting a low pass filtered video signal 111 from the input video signal 102 and a signal 121 subtracted from the low pass filtered video signal 111 from the video signal 102; A delay contour correction unit 200 receiving the low-pass filtered video signal 111 and outputting a video signal 221 of a contour-corrected low-frequency component; A delay amplifier 300 for receiving the subtracted signal 121 and outputting a signal 331 which suppresses and amplifies noise of a high frequency component; And The summation unit 400 outputs the contour-corrected low-frequency component video signal 411 by synthesizing the suppressed amplified signal 331 of the high frequency portion with the contour-corrected low-frequency component video signal 221. Noise removal method, characterized in that made. The method of claim 5, wherein the low-pass subtraction section 100 A low pass filter (110) for low-pass filtering the video signal (102) to output the low-pass filtered video signal (111); And And a subtractor (120) for subtracting the low pass filtered signal (111) from the sound video signal (102) to output the subtracted signal (121). The method of claim 5, wherein the delay contour correction unit 200 A first delay unit (210) for delaying the low-pass filtered video signal (111) to output a first delayed signal (211); And And a contour correction circuit (220) for receiving the first delayed signal (211) and edge compensating to output the contour corrected low-pass component video signal (221). The method of claim 5, wherein the delay amplifier 300 An energy detector 310 for receiving the subtracted signal 121 and outputting a control signal 311 for detecting an energy or noise level and adjusting an amplification factor α; A second delay unit (320) for delaying the subtracted signal (121) to output a second delayed signal (321); And And an amplifier (330) for suppressing and amplifying the second delayed signal (321) at the amplification factor α adjusted by the control of the control signal (311). The method of claim 5, wherein the adder 400 A summator for adding the contour corrected low pass component video signal 221 and the high frequency component suppressed signal 331 to output the contour corrected low pass component video signal 411. 410, characterized in that consisting of a noise removing circuit.