KR960003941Y1 - Image quality automatic compensation apparatus of vcr - Google Patents

Abstract

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Description

V-Cal Automatic Image Correction Device

1 is a block diagram of a conventional automatic automatic image quality correction V.

2 is a detailed block diagram of a conventional noise canceling unit according to FIG.

3 is a characteristic curve diagram of a conventional noise removing unit.

4 is a block diagram of the automatic image quality correction device of the subject innovation V-real.

5 is a characteristic curve diagram of the noise canceling unit of the present invention.

* Explanation of symbols for main parts of the drawings

1: playhead 2: FM demodulator

3: de-emphasis section 4, 12: noise removal section

5: high frequency filter unit 6: limiter

7: low frequency filter unit 8: attenuator

9: Variable device 10: Control signal output unit

11: comparison unit

The present invention relates to an automatic image quality correcting device of a BC-R, and more particularly, to an automatic image quality correcting device of a BC-AL which automatically removes a noise component according to the size of a reproduction signal when the video signal of the BC-AL is reproduced.

FIG. 1 is a block diagram of a conventional automatic image quality correcting device of a VR, and as shown therein, an FM demodulation unit 2 for FM demodulating a video luminance signal reproduced from a playback head 1, and the FM demodulation unit. De-emphasis unit 3 which de-emphasizes the image luminance signal demodulated in (2) and compensates with the original image luminance signal, and removes noise components included in the output signal A of the de-emphasis unit 3 The noise removing unit 4 which generates the reproduction luminance signal Y is constituted.

In the automatic image quality correcting apparatus of V-C configured as described above, the noise removing unit 4 filters the high frequency component from the output signal A of the de-emphasis unit 3 as shown in FIG. A filter unit 5, a limiter 6 for shaping the output signal of the high frequency filter unit 5, and a low-frequency filter unit 7 for filtering the signal shaped by the limiter 6 and outputting a DC component. And an attenuator 8 whose attenuation amount varies according to the output signal of the low frequency filter unit 7 and an output signal A of the deemphasis unit 3 according to the attenuation amount of the attenuator 8. It consists of a variable 9 for removing the noise by varying the high frequency components.

The operation and problems of the conventional VRC image quality correction device configured as described above are as follows.

When the reproduction head 1 reproduces the image luminance signal from the tape, the image luminance signal is demodulated by the FM demodulator 2, and the demodulated image luminance signal is input to the de-emphasis unit 3.

Accordingly, the de-emphasis unit 3 de-emphasizes the image luminance signal and compensates for the signal that is emphasized when recording, to the original correct signal, and outputs the compensated signal to the noise removing unit 4 (A). )do.

In this way, the high frequency component is filtered by the high frequency filter unit 5, and the signal A input to the noise removing unit 4 is filtered by the limiter 6 to form a low frequency filter. The low frequency filter unit 7 is inputted to the unit 7, and the low frequency filter unit 7 outputs a DC component by filtering this signal.

At this time, the DC level of the DC component changes according to the output signal of the de-emphasis unit 3, that is, if the output A of the de-emphasis unit 3 is large, the DC level is high and the output A is small. The DC level is low.

The attenuation amount of the attenuator 8 varies according to the DC component. If the output A of the de-emphasis unit 3 is large, the attenuation amount of the attenuator 8 is made small, and if the output A is small, the attenuator 8 is reduced. Increase the attenuation of).

When the output of the attenuator 8 to be attenuated as described above is input to the variable unit 9, the variable unit 9 outputs the output signal A of the deemphasis unit 3 according to the attenuation amount of the attenuator 8. The high luminance component Y is removed to output the reproduced luminance signal Y.

The characteristic curve of the noise removing unit 4 is shown in FIG.

In other words, as the output of the de-emphasis unit 3 decreases, the noise canceling unit 4 removes more high frequency components. This means that the lower the input, the larger the amount of noise, and thus the greater the elimination. .

However, since the noise reduction ratio of the noise canceling unit 4 is determined in the conventional VRC image correction device described above, when the dark screen is reproduced, the high frequency component is attenuated as the noise is removed, so that the edge of the screen is reduced. In the case of repetitive bright screens or bright and dark screens, although the boundaries are blurred, the boundaries of the screens can be distinguished, but in the case of dark screens, there is a problem in that the outline of the object cannot be clearly seen because the boundaries cannot be distinguished. .

In order to solve this problem, the present invention has a small amount of attenuation of the noise canceling unit in a dark screen so that the high frequency component is not greatly attenuated so that the boundary of the object is more accurately determined. An automatic image quality correction device is devised, which will be described in detail with reference to the accompanying drawings.

4 is a block diagram of an automatic image quality correcting apparatus of the present invention, as shown in the FM demodulation unit 2 for demodulating the image luminance signal reproduced from the playback head 1, and the FM demodulation unit ( 2) a deemphasis section 3 for de-emphasizing the output signal of 2) to compensate for the original video luminance signal, and a noise of a high frequency component from the output signal A of the deemphasis section 3 to remove a reproduction video luminance signal. And a control signal for variably controlling the noise removal amount of the noise removal unit 12 to the noise removal unit 12 corresponding to the output signal of the de-emphasis unit 3. It comprises a control signal output unit 10 for outputting.

The noise removing unit 12 filters the output signal A of the de-emphasis unit 3 to output a high frequency component, and outputs an output waveform of the high frequency filter unit 5. The limiter 6 for shaping, the low frequency filter unit 7 for filtering the output signal of the limiter 6 to output a DC component, and the low frequency filter unit 7 and the control signal output unit 10 A comparator 11 for receiving an output signal and comparing the magnitudes of the two signals, attenuator 8 having attenuated amount varying according to the comparative output signal of the comparator 11, and attenuated amount of the attenuator 8; Accordingly, the high frequency component included in the output signal A of the de-emphasis unit 3 is configured to vary the high frequency component and output a reproduction luminance signal Y. In addition, the control signal output unit 10 includes, for example, a low frequency filter.

Referring to the effect of the present invention configured in this way in detail as follows.

When the reproduction head 1 reproduces the image luminance signal from the tape, the image luminance signal is FM demodulated by the FM demodulation unit 2, and the FM demodulated image luminance signal is input to the de-emphasis unit 3.

Accordingly, the de-emphasis unit 3 de-emphasizes the image luminance signal and compensates the signal emulated at the time of recording with the original correct image luminance signal A to remove the noise 12 and the control signal output unit ( Output to 10).

As the image luminance signal A is input to the control signal output unit 10 as described above, a control signal corresponding to the image luminance signal A is output and input to the comparison unit 11. That is, when the control signal output unit 10 is configured as a low frequency filter, the image luminance signal A is low-pass filtered by the control signal output unit 10 to be a direct current component, and the direct current component is a comparator ( 11) is entered.

In addition, the high luminance component A of the image luminance signal A output to the de-emphasis unit 3 is filtered by the high frequency filter unit 5, and the high frequency component is shaped by the limiter 6 to form a low frequency band. Input to the frequency filter unit 7, the low-frequency filter unit 7 filters this signal and outputs a DC component to the comparison unit (11).

At this time, when the level of the output signal A of the de-emphasis unit 3 is large, the level of the DC component output from the control signal output unit 10 is high, and the level of the output signal A is high. In the small case, the level of the DC component is low.

In addition, the DC component output from the low frequency filter unit 7 appears at a high level when the high frequency component of the output signal A is large, and at a low level when the high frequency component is small.

Accordingly, the comparison unit 11 compares the DC level output from the low frequency filter unit 7 and the control signal output unit 10 to adjust the attenuation amount of the attenuator 8. That is, when the DC level of the control signal output unit 10 is high, the comparator 11 outputs the same value as the DC level of the low-frequency filter unit 7 so that the attenuator 8 is connected to the solid line of FIG. When the attenuation amount is largely changed, and the DC level of the control signal output unit 10 is low, the comparator 11 outputs an output value such that the attenuator 8 changes the attenuation amount small as in the dotted line of FIG.

Accordingly, the variable unit 9 changes the magnitude of the high frequency component of the image luminance signal A output from the de-emphasis unit 3 according to the attenuation amount of the attenuator 8 to output the reproduction luminance signal Y. do.

As described above, the present invention can make the boundary of the screen clear by reducing the attenuation of the high frequency component when the screen is dark, so that the object can be easily distinguished even in the dark screen.

Claims (3)

An FM demodulator for demodulating the video luminance signal reproduced from the playhead, a de-emphasis unit for de-emphasizing the output signal of the FM demodulator and compensating for the original image luminance signal, and a high frequency component in the output signal of the de-emphasis unit. A noise removing unit for removing a noise and outputting a reproduced video luminance signal, and a control signal output unit for outputting a control signal for controlling the removal amount of the noise removing unit to the noise removing unit in accordance with an output signal of the deemphasis unit; Automatically correcting the image quality of VCC comprising a configuration. The apparatus of claim 1, wherein the control signal output unit is configured as a low-frequency filter for low-pass filtering the output signal of the de-emphasis unit. 2. The noise canceling unit of claim 1, wherein the noise removing unit receives an output signal of the de-emphasis unit and filters a high frequency component, a limiter for shaping the output signal of the high frequency filter unit, and a low pass filtering of the output signal of the limiter. A comparator for receiving the low frequency filter unit, an output signal of the low frequency filter unit and an output signal of the control signal output unit, and comparing the magnitudes of the two signals; And a variable group configured to output a reproduction luminance signal by varying a high frequency component included in the output signal of the de-emphasis unit according to the amount of change of the attenuator.