JPH0250678A - Picture quality adjusting device - Google Patents

Abstract

PURPOSE:To obtain excellent contour emphasis without emphasizing a noise component by using a slicer so as to eliminate the noise component in a vertical direction noncorrelation component and adding the component to an original video signal. CONSTITUTION:A subtractor 23 applies subtraction processing between a retarded video signal and a direct video signal from an input terminal 21 to lead out a vertical noncorrelation component. The vertical noncorrelation component is given to the slicer 24 to eliminate the noise component, the result is led out as an excellent signal representing a horizontal contour, the level is adjusted by a level adjustment device 25 and given to an adder 26. The adder 26 adds the contour signal and the video signal from the input terminal 21 to lead out the video signal subject to contour correction to an output terminal 27. Thus, stable vertical picture quality adjustment is obtained without emphasizing the noise component.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an image quality adjustment device used in a video signal processing section of a video tape recorder, a television receiver, etc.

(Prior Art) Generally, a video signal processing circuit of a device that handles television signals is provided with an image quality adjustment circuit. There are two types of image quality adjustment circuits: horizontal image quality adjustment circuits that can emphasize horizontal edges (displayed as vertical lines on the screen, for example), and vertical edges (displayed as horizontal lines on the screen). There is a vertical image quality adjustment circuit.

FIG. 5 shows the principle of the horizontal image quality adjustment circuit, and FIG. 6 shows the principle of the vertical image quality adjustment circuit.

The horizontal image quality adjustment circuit operates on high frequency components of horizontal lines of the video signal. A low-pass filter 2 extracts a low-frequency component of the video signal at an input terminal 1, and the extracted low-frequency component is supplied to an adder 3. Further, a high frequency component of the video signal at the input terminal 1 is extracted by a second order differentiation circuit 4, and after being adjusted by a level adjuster 4, the high frequency component is supplied to an adder 5. Thereby, by adjusting the amount of attenuation of the level adjuster 4, the video signal at the output terminal 6 can have vertical line contours emphasized or reduced on the screen.

The vertical picture quality adjustment circuit operates on uncorrelated components between horizontal lines of the video signal. The video signal at the input terminal 11 is supplied to a one horizontal period delay circuit 12 . The delayed video signal from the delay circuit 12 and the direct video signal from the input terminal 11 are subjected to subtraction processing by a subtracter 13. As a result, the subtracter 13 derives uncorrelated components that have no correlation between horizontal lines. This uncorrelated component is adjusted by a level adjuster 14 and supplied to an adder 15.

In this adder 15, the video signal from the input terminal 11 and the vertical non-correlation component from the level adjuster 14 are added. Therefore, by adjusting the amount of attenuation of the level adjuster 14, the video signal at the output terminal 16 can enhance or reduce the outline of horizontal lines on the screen.

(Problems to be Solved by the Invention) Among the above-described image quality adjustment circuits, the vertical image quality adjustment circuit shown in FIG. 6 in particular has the following problems.

For example, a video signal reproduced from a video tape recorder contains crosstalk noise, so when this video signal is supplied to the vertical image quality adjustment circuit, the noise component is misjudged as a horizontal contour component, and the noise component is The problem is that it is emphasized. The frequency characteristics of the vertical image quality adjustment circuit are expressed as shown in Figure 7, and are uncorrelated components (n±(1/2 > l fH) where n is an integer and fH is the increase in horizontal scanning frequency gain. For this reason, if noise such as crosstalk noise, rather than contour components, exists in the band where this gain is large, it will be emphasized.

Furthermore, in conventional systems, the horizontal and vertical image quality adjustment circuits are adjusted independently and separately, making it difficult to balance the degree of emphasis on horizontal contours and the degree of emphasis on vertical contours. The problem is that it is difficult.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image quality adjustment device that improves the quality of vertical image quality adjustment without emphasizing the noise of vertically uncorrelated components, and that can easily achieve a balance with horizontal image quality adjustment. shall be.

[Structure of the Invention] (Means for Solving the Problems) In the present invention, a non-correlated component detection means detects a delayed video signal obtained by delaying a video signal introduced into an input terminal by a one horizontal period delay circuit, and the input terminal. A direct video signal from the subtracter is supplied to a subtracter, a vertically uncorrelated component is detected from the subtracter, and this vertically uncorrelated component is supplied to a slicer to remove the noise component and extract the contour component. However, this contour component is level-controlled by an adjusting means and added to the video signal of the input terminal to derive a contour-corrected video signal.

(Operation) With the above means, the vertically uncorrelated component is added to the original video signal after the noise component is removed by the slicer, so the noise component is not emphasized and high-quality edge enhancement is obtained. be able to.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. The video signal introduced into the input terminal 21 is delayed by one horizontal period in the one horizontal period delay circuit 22, and is supplied to the subtracter 23 as a delayed video signal. This subtracter 23 performs subtraction processing between the delayed video signal and the direct video signal from the input terminal 21, and a vertically uncorrelated component is derived at its output.

The vertically uncorrelated components are manually inputted to the slicer 24 to remove their noise components, and are then processed into a high-quality one that shows the contour in the horizontal direction.
It is derived as No. 8. This contour component is level-adjusted by a level adjuster 25 and input to an adder 26. This adder 26 adds the contour signal and the video signal from the input terminal 21 and outputs a contour-corrected video signal to the output terminal 27.

According to such a configuration, since noise components having no correlation in the vertical direction are removed in the slicer 24, stable vertical image quality adjustment can be obtained without emphasizing noise components as in the conventional case.

FIG. 2 shows another embodiment of the invention. The difference from the previous embodiment is that the output of the subtracter 3 is further supplied to a limiter 30. Further, an adder 31 is provided between the addition 2''A 26 and the output terminal 27, and here, the output (noise) from the limiter 30 and the output (video signal) from the adder 26 are subjected to subtraction processing. Since the other parts are the same as the embodiment shown in FIG. 1, they are given the same reference numerals as in FIG.

FIG. 3 shows examples of signal waveforms (a) to (f) of each part (a) to (f) of the circuit in FIG. 2.

(a) is a human-powered video signal, and (b) is the output of the one-water delay circuit 22. (c) is the vertically uncorrelated component obtained by the subtraction process in the subtracter 23, and (
d) is a contour component from which noise components have been removed by the slicer 24, and (e) is a noise component obtained from the limiter 30. And (f) is a video signal derived to the output terminal 27, from which noise has been removed and contours have been emphasized.

FIG. 4 shows yet another embodiment of the invention.

This embodiment is an example in which a horizontal image quality adjustment circuit 40 is connected after the vertical image quality adjustment circuit, and is configured so that horizontal image quality adjustment and horizontal image quality adjustment can be obtained in a well-balanced manner.

That is, the output of the adder 26 is further supplied to one of the second-order differentiator circuit 41 and the subtracter 43. The output of the second-order differentiator 41 is adjusted by a level adjuster 42 and then input to the other subtracter 43. The output of this subtracter 44 is then delivered to an output terminal 45.

The level adjusters 2'5 and 42 are configured to be supplied with a regulated voltage from a common control terminal 47. Therefore, according to this embodiment, vertical and horizontal contour adjustments can be obtained in a well-balanced manner.

[Effects of the Invention] As explained above, according to the present invention, the vertical image quality is improved by 2! without emphasizing the noise of the vertical uncorrelated component. It is easy to achieve a balance between horizontal image quality adjustment and horizontal image quality adjustment, and is especially suitable for video signals that include crosstalk noise. Furthermore, a noise canceller function can be easily added, which is effective when reducing noise.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment of the invention, FIG. 3 is a diagram showing examples of signal waveforms at various parts of the circuit of FIG. FIG. 4 is a block diagram showing a conventional horizontal image quality adjustment circuit, FIG. 6 is a block diagram showing a conventional vertical image quality adjustment circuit, and FIG. 7 is a frequency characteristic diagram of the circuit shown in FIG. 22...1 horizontal period delay circuit, 23,31.43...
・Subtractor, 24...Slicer, 25.42...Level adjuster, 26...Adder, 30...Slicer, 4
1...Second order differential circuit. Applicant's agent Patent attorney Takehiko Suzue No. 3 Figure 6 Figure 6 Procedural amendment (method) % formula % Relationship with the case of the person making the amendment

Claims (1)

[Claims] A delayed video signal obtained by delaying a video signal introduced into an input terminal by a one-horizontal period delay circuit and a direct video signal from the input terminal are supplied to a subtracter, and a vertically uncorrelated component is detected from this subtracter. a slicer for removing noise components from the output of the uncorrelated component detecting means and extracting contour components; an adjusting means for controlling the level of the output of the slicer; An image quality adjustment device comprising: an adding means for adding a contour component and a video signal of the input terminal to derive a contour-corrected video signal.