JPH02154577A - Video signal processor - Google Patents

Abstract

PURPOSE:To contrive the effective use of two delay means by extracting a differential component from 3 signals, retarded signals by 1st and 2nd delay times and an original signal, using the component for a contour correction means when the level is large and using the component for a noise reduction means when the level is smaller. CONSTITUTION:When a signal including a noise component is inputted, outputs of 1st and 2nd means 2, 3 are (b), (c), the output of a 1st adder is (d), and the output of a 1st subtractor 6 is (e) and the output of a limiter 13 is a waveform (h) being the result of extracting a noise component of the flat part of the input signal. When the coefficient K1 of a coefficient circuit 14 is set properly, a signal (i) being the result of reducing the noise component remarkably is obtained at the output of the 2nd subtractor 15. Moreover, a waveform (j) being the result of extracting a difference component near the contour is obtained at the output of a slicer 16 and a signal in which the noise component of a flat part is remarkably reduced and pre-shoot and overshoot having a time interval T are added from the 2nd adder 8 is obtained by setting properly the coefficient K2 of the circuit 7. Thus, two delay means are used effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video signal processing device used as means for improving image quality in a magnetic recording/reproducing device or the like.

2. Description of the Related Art Conventionally, contour correction means or noise reduction means have been widely used as means for improving image quality using delay means.

FIG. 3 shows a block diagram of an example of a conventional video signal processing device.

In FIG. 3, the signal input to input terminal 1 is
The signal is supplied to the second delay means 3 and the edB amplifier 4 via the delay means 2 . The output of the second delay means 3 is added to the signal input to the input terminal 1 in the first adder 6.

The output of the edB amplifier is supplied to a subtracter 6, and the difference component from the output of the first adder 5 is supplied to a coefficient circuit 7 and converted to a predetermined level. It is added to the output of the first delay means 2 and output to the output terminal 9.

Here, the output of the subtracter 6 is the difference component between the output of the first delay means 2 and the signal input to the input terminal 1, and the output of the first delay means 2 and the output of the second delay means 3. This is the same signal obtained by adding the difference components of 3...-7.

FIG. 4 shows a waveform diagram for explaining the operation of the conventional example shown in FIG. 3. For the sake of simplicity, it is assumed that the delay times of the first delay means 2 and the second delay means 3 are the same value T.

When the signal shown in FIG. 4a is input to the input terminal 1, the outputs of the first delay means 2 and the second delay means 3 are as shown in FIG. 4A and C, respectively.

Therefore, the output of the first adder 5 is as shown in FIG. 4d, and the output of the subtracter 6 is as shown in FIG. 4e. Furthermore, the coefficient K of the coefficient circuit 7 is set appropriately (in FIG.
．． 4) As a result, the output terminal 9 has the following as shown in Fig. 4f.
A waveform to which preshoot and overshoot are added, both of which have a time width T, can be obtained. That is, the conventional example shown in FIG. 3 is a contour correction means.

Here, the time width T is usually set to several hundred nanoseconds (nanoseconds), but this is set to one horizontal scanning period (1H) or one horizontal scanning period (1H).
By setting the frame period, more effective contour correction may be performed.

FIG. 5 shows another example of a conventional video signal processing device.

In FIG. 5, the signal input to the input terminal 1 is supplied to the first subtracter 12 via the delay means 11, and the difference component between the input signal and the output of the delay means 11 is obtained and the limiter circuit 13.

The large amplitude component of the difference component is limited by the limiter circuit 13, converted to a predetermined level by the coefficient circuit 14, and then subtracted from the input signal by the second subtracter 15 and output to the output terminal 9. .

FIG. 6 shows a waveform diagram for explaining the operation of the conventional example shown in FIG. Let T be the delay time of the delay means 11.

When a signal containing a noise component as shown in FIG. 6a is input to the input terminal 1, the output of the delay means 11 is as shown in FIG. 6, and the output of the subtracter 12 is as shown in FIG. 6q. become. Therefore, the output of the limiter circuit 13 becomes as shown in Fig. 6, and by setting the coefficient K of the coefficient circuit 14 appropriately (to 0.5 in Fig. 5), the output terminal 9 becomes as shown in Fig. 6. It is possible to obtain a waveform such as \-7f in which the noise component in the flat part is significantly reduced. That is, the conventional example shown in FIG. 5 is a noise reduction means.

Problems to be Solved by the Invention When the above-mentioned conventional techniques are used in combination, the number of delay means and adders/subtracters required increases, making the system expensive. A broken delay means itself may cause S/N deterioration.

In view of the above problems, the present invention provides a video signal processing device that can perform contour correction and noise reduction satisfactorily using two delay means.

Means for Solving the Problems In order to solve the above-mentioned problems, the video signal processing device of the present invention includes a first delay means for delaying an input signal by a first delay time, and an output of the first delay means. a second delay means for further delaying the signal by a second delay time; a first subtracter for extracting a difference component between the output signal of the first delay means and the input signal; and the first delay means. a second 6-page subtracter for extracting a difference component between the output signal of the output signal and the output signal of the second delay means; and a second 6-page subtracter for adding the output signal of the first subtracter and the output signal of the second subtractor. an adder; and a mixing means for determining the output level/L/total of the adder and mixing the output signal of the subtracter with the output signal of the biopsy of the first delay means in a polarity and ratio according to the level. The configuration is such that it includes the following.

Effect: With the above-described configuration, the present invention extracts the difference component from three signals: the signal delayed by the first delay time, the signal further delayed by the second delay time, and the original signal, and calculates the level of the difference component. When the level is large, it works as a contour correction means, and when its level is small, it works as a noise reduction means, so the two delay means can be used effectively.

Embodiments Hereinafter, embodiments of a video signal processing apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of the present invention.

In FIG. 1, the signal input to input terminal 1 is
The signal is supplied to the second delay means 3 and the 67'\-.dB amplifier 4 via the delay means 2. The output of the second delay means 3 is added to the signal input to the input terminal 1 in the first adder 5. The output of the edB amplifier is supplied to the first subtracter 6, and the difference component from the output of the first adder 5 is extracted.
It is supplied to a limiter 13 and a slicer 16. Limiter 1
3, a signal smaller than a predetermined level value is extracted and supplied to the second subtracter 16 via the coefficient circuit 14, where it is subtracted from the output of the first delay means. In the slicer 16, a signal larger than a predetermined level value is extracted and supplied to the second adder 8 via the coefficient circuit 7, where it is subtracted from the output of the second subtracter 15 and sent to the output terminal. 9 is output.

FIG. 2 shows a waveform diagram for explaining the operation of the embodiment shown in FIG. 1. For simplicity, it is assumed that the delay times of the first delay means 2 and the second delay means 3 are the same value T.

When a signal containing a noise component is input to the input terminal 1 as shown in Fig. 2a, the outputs of the first delay means 2 and the second delay means 3 are as shown in Fig. 2A and C, respectively. Become. Therefore, the output of the first adder 6 is as shown in FIG. 2d, and the output of the first subtracter 6 is as shown in FIG. 2e. Therefore, the output of the limiter 13 has a waveform that extracts the noise component of the flat part of the input signal as shown in the second figure. By appropriately setting the coefficient of the coefficient circuit 14 to 1, the output of the second subtracter 15 is At the output, a signal with significantly reduced noise components in the flat portion of the input signal is obtained, as shown in FIG. 2i.

In addition, the output of the slicer 16 has a waveform in which the noise component in the flat part of the input signal has been removed and the difference component near the contour has been extracted, as shown in FIG. As a result, the output of the second adder 8, that is, the output terminal 9, has a time width T as shown in FIG.
It is possible to obtain a signal in which a preshoot and an overshoot are added, and the noise component in the flat portion is significantly reduced.

Effects of the Invention As described above, according to the present invention, two delays 9'\
-7 By simply using the means, it is possible to realize a video signal processing device that can effectively perform both the contour correction means and the noise reduction means.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a video signal processing device according to the present invention, FIG. 2 is a waveform diagram for explaining the operation of FIG. 1, and FIG. 3 is a block diagram showing a conventional video signal processing device. Figure 4 is a waveform diagram for explaining the operation of Figure 3,
FIG. 5 is a block diagram showing a conventional video signal processing device, and FIG. 6 is a waveform diagram for explaining the operation of FIG. 5. 1... Input terminal, 2, 3, 11... Delay means, 4... Amplifier, 5, 8... Adder, 6, 12゜15・・・・・・Subtractor, 7, 14・
... Coefficient circuit, 9 ... Output terminal, 13.
...Limiter, 16...Slicer. Name of agent: Patent attorney Shigetaka Awano and 1 other person 1st
Figure →←--T E'03 Figure 1-page →←＋←T

Claims (1)

[Claims] a first delay means for delaying the input signal by a first delay time; a second delay means for further delaying the output signal of the first delay means by a second delay time; and the first delay means. A first step for extracting a difference component between the output signal of the input signal and the input signal.
a second subtracter that extracts a difference component between the output signal of the second delay means and the output signal of the first delay means; an adder that adds the output signals of the subtracters; and an adder that determines the level of the output signal of the adder and adds the output signal of the subtracter to the output signal of the first delay means with a polarity and ratio according to the level. 1. A video signal processing device comprising: a mixing means for mixing.