JPH08191407A - Video signal processing circuit - Google Patents

Abstract

PURPOSE: To suppress noise or jitter at both left and right ends of an image extended in the lateral direction so as not to be made distinct by generating a control signal different from an image middle part and both left and right ends of an image for one horizontal scanning period so as to use the control signal to change a degree of noise control or the like. CONSTITUTION: A synchronizing separator circuit extracts a horizontal synchronizing signal from a VTR reproduced video signal and an image adjustment signal generating circuit generates an outputs a control signal different from a middle part and both left and right ends of an image for one horizontal period (1H). Noise reduction is conducted based on the control signal in which a degree of suppressing noise at both left and right ends more than a middle part of an image based on the control signal is enhanced thereby making noise or jitter at both left and right ends of an image extended in the lateral direction based on video aspect ratio conversion in, e.g. the panorama mode unremarkable. Or the similar effect is obtained by controlling boosting of a frequency characteristic in place of the noise reduction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing circuit, and more particularly to a video signal processing circuit for reproducing a horizontally long so-called wide screen video from a conventional aspect ratio of 4: 3.

[0002]

2. Description of the Related Art In recent years, high-definition broadcasting, CATV, B
With the development and popularization of S / CS broadcasting and the like, the aspect ratio of 16:
9 wide-screen TVs and monitors are rapidly becoming widespread, and at present it can be said that the transition from 4: 3 to 16: 9 is in transition. However, most of the video software has an aspect ratio of 4: 3, and in order to project these videos on a wide screen, the video should be displayed with the upper and lower parts of the screen cut off or left and right ends opened. However, there was no choice but to reduce the screen size and display it, and it was not possible to display a realistic image on the entire 16: 9 wide screen.

Therefore, prior to the present invention, the applicant company developed a video aspect ratio conversion technique called panorama mode (“Panorama” is a trademark of Victor Company of Japan, Ltd.) and has already applied for a patent (patent pending). Kaihei 6-6634). In this panorama mode, as shown in FIG. 5, only the left and right ends of the screen are expanded and displayed, and the aspect ratio of originally 4: 3 is changed to the aspect ratio of 16: 9 to be displayed on the display. That is, the resonance current in which the capacitance of the S-shaped correction capacitor is increased and the resonance frequency is lowered is superimposed on the horizontal deflection current. By such an operation, for example, the central portion of the screen corresponding to 70% in the horizontal direction is left as it is (within ± 5%), and the left and right ends are enlarged by about + 15%.

In the above-mentioned conventional video signal processing circuit for performing pseudo conversion of the aspect ratio called the panorama mode, 4: is used.
It is an excellent technology in that it can convert the video of No. 3 to a 16: 9 screen with a sense of realism, and has high utility value.

[0005]

In such a conventional video signal processing circuit, when a video signal containing a lot of jitter components and noise, such as a reproduced signal from a VTR, is input, the reproduced image is horizontally moved to the left and right ends. There has been a problem that noise and jitter in flat portions and edge portions in the image are more noticeable in the enlarged (expanded) portion than in the central portion of the screen. Furthermore, in such a conventional video signal processing circuit, the left and right ends of the image are enlarged (expanded) in the horizontal direction, so the resolution in that part is lower than in the central part. Therefore, in a reproduction signal or the like from a VTR having a narrow frequency band, an image that lacks sharpness in the horizontally expanded (extended) portions at the left and right ends of the reproduced image compared to the central portion of the screen. There was a problem.

Therefore, the present invention provides a video signal processing circuit capable of making noise and jitter inconspicuous at both left and right ends of an image enlarged in the horizontal direction by a so-called panoramic mode image aspect ratio conversion technique. The purpose is to provide. Further, the present invention provides a video signal processing circuit capable of reproducing an image in which both the left and right ends of the image enlarged in the horizontal direction are less sharp than the central part of the screen. With the goal.

[0007]

In order to achieve the above object, the present invention provides a control signal generating means for producing control signals having different characteristics at the central portion and the left and right end portions of an image in one horizontal scanning period of a video signal. In response to the control signal, noise reduction means capable of increasing the degree of suppressing the noise in the video signal at the left and right end portions with respect to the central portion of the image in one horizontal scanning period is provided, or the control signal is also provided. In response, frequency characteristic control means is provided which can raise the frequency characteristic of the video signal at the left and right ends with respect to the central portion of the image in one horizontal scanning period.

That is, according to the present invention, the control signal generating means is responsive to the horizontal synchronizing signal of the video signal to generate a control signal having different characteristics between the central portion and the left and right end portions of the image in one horizontal scanning period of the video signal. , Of the video signal in response to the control signal
Noise reduction means capable of increasing the degree of suppressing the noise in the video signal at the left and right end portions with respect to the central portion of the image in the horizontal scanning period, and the central portion of the image in the one horizontal scanning period in response to the control signal. There is provided a video signal processing circuit having one or both of frequency characteristic control means capable of raising the frequency characteristic of the video signal at the left and right ends of the portion.

Further, according to the present invention, control signal generating means for responding to the horizontal synchronizing signal of the video signal, for producing control signals having different characteristics at the central portion and the left and right end portions of the image in one horizontal scanning period, and control. A noise reduction means capable of responding to the signal and increasing the degree of suppressing the noise in the video signal at the left and right ends with respect to the central portion of the image in one horizontal scanning period of the video signal; and a series of noise reduction means. And a frequency characteristic control means that is responsive to the control signal and that can raise the frequency characteristic of the video signal at the left and right end portions with respect to the central portion of the image in one horizontal scanning period of the video signal. A signal processing circuit is provided.

[0010]

Since the present invention has the above-mentioned structure, in the aspect in which the noise reduction means capable of increasing the degree of suppressing the noise in the video signal at the left and right end portions with respect to the central portion of the image is provided, the video aspect ratio conversion technique The noise and jitter at the left and right edges of the horizontally enlarged image can be made inconspicuous, and the frequency characteristics of the video signal at the left and right edges can be raised relative to the center of the image. In the mode in which the frequency characteristic control means capable of performing the above is provided, it is possible to reproduce an image in which sharpness is not lost as compared with the central portion of the screen at the left and right ends of the image that has been laterally enlarged. Further, in the mode in which the noise reduction means and the frequency characteristic control means are connected in series, the effects obtained from the respective means can be obtained together, so that more preferable image quality improvement can be performed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a first video signal processing circuit according to the present invention.
2 is a block diagram of the embodiment, and FIG. 2 is a signal waveform diagram for explaining the operation of the first embodiment. In the input terminal 10,
For example, a reproduction luminance signal supplied from a VTR (not shown) is input. The reproduction luminance signal is given to the noise canceller 12 and the sync separation circuit 14. The noise canceller 12 includes a delay circuit 20, a subtractor 28, an HPF 22, and a limiter 24.
And VCA (voltage controlled amplifier) 26. In the noise canceller 12, the HPF 22 extracts a high-frequency component from the reproduction luminance signal, the limiter 24 limits the amplitude, and only a minute signal is regarded as noise, and the subtractor 28 subtracts it from the reproduction luminance signal. Has become.

The VCA 26 is an amplifier whose gain changes according to the voltage of the control signal. The sync signal separation circuit separates and extracts the horizontal sync signal shown in FIG. 2B from the reproduction luminance signal shown in FIG. The control signal generation circuit 16 generates a control signal that changes in a predetermined manner over one horizontal scanning cycle determined by two consecutive horizontal sync signals separated by the sync signal separation circuit 14. In the change mode of this control signal over one horizontal scanning cycle, as shown in (c) of FIG. 2, for example, the voltage is low in the part corresponding to the central part of the image and is low in the parts corresponding to the left and right ends of the image. The trapezoidal shape can be increased. Further, the change mode of the control signal may not be abruptly changed like a trapezoid but may be changed in a curved shape, that is, gently as shown in FIG. The ratio between the center of the screen and the left and right ends is determined according to the video aspect ratio conversion technique to be applied. In the panorama mode described above, the voltage at the center of the screen corresponding to 70% in the horizontal direction is The voltage is changed so that the voltage is high at the left and right ends of the remaining 30%.

Since the control signal changes in one horizontal scanning period as shown in (c) or (d) of FIG. 2, the amount of noise cancellation at both end portions of the screen becomes larger than that at the central portion, and increases due to horizontal expansion. Noise that tends to stand out can be effectively suppressed. The luminance signal in which the noise is suppressed can be supplied to a wide-screen television vision or a display (not shown) via the output terminal 18.

Next, a second embodiment of the video signal processing circuit of the present invention will be described. FIG. 3 is a block diagram showing the second embodiment. This embodiment differs from the first embodiment in the following points. That is, the noise canceller in the first embodiment cancels noise only in the horizontal direction, but in this embodiment, the H correlation noise canceller 13 (line noise canceller) using the vertical correlation of the image is used. Therefore, it is possible to effectively suppress the edge noise that tends to stand out due to the horizontal enlargement at the image end portion. In FIG. 3, reference numeral 30 is a 1H delay line, 32 is a subtractor, 34 is an amplifier, and the other components are the same as those in FIG.

Next, a third embodiment of the video signal processing circuit of the present invention will be described. FIG. 4 is a block diagram showing the third embodiment. This embodiment differs from the first embodiment in the following points. That is, in the first embodiment, the degree of noise cancellation in the noise canceller is controlled according to the control signal, but in the present embodiment, the frequency characteristic control circuit 36 for changing the frequency characteristic is controlled. That is, according to the control signal generated by the control signal generation circuit 16, the frequency characteristic is raised by the amount that the horizontal resolution is lowered due to the enlargement of the both ends of the screen, and the sharpness of appearance is improved. Therefore, the visual sharpness is made uniform on the screen.

In the third embodiment, the noise canceller of the first embodiment or the second embodiment and the frequency characteristic control circuit 36 are connected in series, so that the noise canceller tends to stand out due to the horizontal expansion at the end of the screen. The edge noise is effectively suppressed, and the frequency characteristics are raised by the amount by which the horizontal resolution is reduced due to the enlargement of both edges of the screen, improving the sharpness of appearance. As a result, a large-amplitude signal is emphasized to improve the sharpness, and a small-amplitude signal is reduced to reduce noise, so that more preferable image quality can be improved.

Although each of the above-described embodiments is applied to the luminance signal of the video signal, it may be applied to the color signal or may be applied to both the luminance signal and the color signal. Further, a transient characteristic improving circuit for a color signal, for example, a "rectangular modulation chroma enhance circuit" for emphasizing an aperiodic transient characteristic of a rectangular modulation subcarrier based on a control signal obtained from the baseband of the carrier (U.S. Pat. No. 504, 853), it is possible to further improve the image quality by increasing the degree of improvement in the transient characteristic of the color at both ends of the screen.

The video signal processing circuit of the present invention is incorporated in a VTR to supply a wide-screen television or display with a video signal which suppresses an increase in noise and / or a decrease in horizontal resolution due to enlargement on the left and right ends of the screen. You can also do it. In this case, it is possible to provide an output terminal dedicated to the video signal for wide screen and output the signal via the video signal processing circuit from this output terminal.If such an exclusive output terminal is not provided, use a manual switch. It is possible to have a configuration in which a signal passing through the video signal processing circuit and a signal bypassing the video signal processing circuit are switched. Further, the video signal processing circuit of the present invention can be incorporated in such a wide screen television or display side. Further, in the television integrated VTR, when the wide screen mode (panorama mode) is selected, the video signal processing circuit of the present invention can be operated with respect to the reproduced video signal from the VTR.

[0019]

As described above, according to the video signal processing circuit of the present invention, the correction is performed at the left and right ends of the image enlarged in the horizontal direction by the video aspect ratio conversion technique, so that the noise and the jitter can be prevented. Can be made inconspicuous, and / or an image can be reproduced in which sharpness is not lost as compared with the central portion of the screen. Further, in the aspect in which the noise reduction means and the frequency characteristic control means are connected in series, the noise reduction means effectively suppresses the edge noise that tends to stand out due to the horizontal expansion at the screen end portion, and then the frequency characteristic control means. However, because the horizontal resolution is reduced due to the expansion of both edges of the screen, it is possible to raise the frequency characteristic and improve the sharpness of the appearance.
More preferable image quality can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of a video signal processing circuit of the present invention.

FIG. 2 is a signal waveform diagram for explaining the operation of the circuit of FIG.

FIG. 3 is a block diagram of a second embodiment of a video signal processing circuit of the present invention.

FIG. 4 is a block diagram of a video signal processing circuit according to a third embodiment of the present invention.

[Explanation of symbols]

10 video signal input terminal 12 noise canceller (noise reduction means) 13 H correlation noise canceller (noise reduction means) 14 synchronization signal separation circuit 16 control signal generation circuit (which constitutes control signal generation means together with the synchronization signal separation circuit 14) 18 video signal output Terminal 20 Delay circuit 22 HPF 24 Limiter 26 VCA (voltage controlled amplifier) 28 Subtractor 30 1H delay line 32 Subtractor 34 Amplifier 36 Frequency characteristic control circuit (frequency characteristic control means)

Claims (2)

[Claims] 1. A control signal generation unit that responds to a horizontal synchronizing signal of a video signal and generates control signals having different properties in the central portion and the left and right end portions of an image in one horizontal scanning period, and in response to the control signal, Noise reduction means capable of increasing the degree of suppressing the noise in the video signal at the left and right end portions with respect to the central portion of the image in one horizontal scanning period of the video signal, and also in response to the control signal,
A video signal processing circuit having one or both of frequency characteristic control means capable of raising the frequency characteristic of the video signal at the left and right ends with respect to the central portion of the image of the video signal in one horizontal scanning period. 2. A control signal generation means that responds to a horizontal synchronizing signal of a video signal and generates control signals having different properties at the central portion and the left and right end portions of an image in one horizontal scanning period, and in response to the control signal, A noise reduction unit capable of increasing the degree of suppressing noise in the video signal at both left and right ends of the center portion of the image in one horizontal scanning period of the video signal, and connected in series to the noise reduction unit. Similarly, in response to the control signal, frequency characteristic control means capable of raising the frequency characteristic of the video signal at the left and right end portions with respect to the central portion of the image in one horizontal scanning period of the video signal, Signal processing circuit.