JPH05300476A - Image quantity improving circuit - Google Patents

Abstract

PURPOSE:To obtain an image quantity improving circuit preventing the degradation of the image quantity to be generated by highly accurate information in a device where the video signal for which highly accurate information is multiplexed is received, and the image with the wide screen of an aspect ratio of 16:9 and with a high accuracy is realized. CONSTITUTION:A control circuit 17 detects the SN ratio of a supplied video signal and a control signal controlling a coefficient multiplier 14 is outputted based on this SN ratio. In a center part reproduction circuit 12, the extension in a vertical direction is performed after the interlaced signal is successively converted into a scanning signal, the video signal of 16:9.525.1:1 are reproduced and they are supplied to an adder 15. In a highly accurate information reproduction circuit 13, various kinds of highly accurate information are reproduced, they are supplied to the coefficient multiplier 14, and they are supplied to the adder 15 after they are made K times. In the adder 15, the output of the coefficient multiplier 14 is added to the video signal and the signal is supplied to a monitor 16. The video 16:9.525.1:1 including the highly accurate information which was made K times is displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image quality improving circuit for providing a high quality image while maintaining compatibility with the current television system.

[0002]

2. Description of the Related Art Currently, second generation EDTV (Extended Def
Various proposals have been made as a transmission / reception system for inition TV. The second-generation EDTV basically aims to realize a wide screen with an aspect ratio of 16: 9 while maintaining compatibility with the NTSC system currently used in Japan. Methods for realizing this wide screen are roughly classified into a letter box method, an intermediate method, and a side panel method. Here, the letterbox method will be described.

In the letter box system,
After the center processing for forming a wide screen and the high-definition information generation processing are performed on the transmitting side, they are multiplexed and transmitted as an RF signal. On the receiving side, the information of the center part and the high-definition information are separated from the RF signal, and the reproduction processing is performed separately for each and added and displayed on the monitor. Here, the configuration of the receiving side is shown in FIG.

The video signal received in FIG.
It is separated by the separation circuit 11 via 0 and supplied to the center reproduction circuit 12 and the high-definition information reproduction circuit 13. In the center reproducing circuit 12, the interlaced signal is converted into a progressive scanning signal and then expanded in the vertical direction. The aspect ratio is 16: 9, the number of scanning lines is 525, and the progressive scanning video signal (hereinafter, 16: 9.525).・ Recorded as 1: 1 video signal)
Is reproduced and supplied to the adder 15.

On the other hand, the high-definition information reproducing circuit 13 reproduces various kinds of high-definition information, and the adder 15 adds the high-definition information to the 16: 9.525.1: 1 video signal output from the center reproducing circuit 12. .. The output of the adder 15 is supplied to the monitor 16 and contains 16: 9 ・ 525 ・ 1: containing high-definition information.
The image of 1 is displayed.

By the way, since the transmitted RF signal decreases as the distance increases, the SN ratio (signal to noise power ratio) on the receiving side deteriorates. As a matter of course, high-definition information also deteriorates. Originally, high-definition information was a signal inserted to improve image quality, but 16: 9.525 including high-definition information when the SN ratio deteriorated.
When a 1: 1 video is played back, the SN ratio of the video may be worse than when there is no high-definition information. That is, receiving SN
When the ratio falls below a certain level, the image quality deteriorates due to the high definition information.

When there is a ghost, a ghost component also exists in high definition information. Therefore, when the high-definition information reproduced on the receiving side is added to the video signal of the center part, the image quality deteriorates.

Further, when a video signal to which high-definition information is added is once recorded and reproduced by a home VTR (video tape recorder), the relationship between vertical synchronization, horizontal synchronization and color subcarrier is broken due to the influence of jitter or the like. Therefore, there is a problem in that high-definition information is not accurately reproduced, or the phase of the high-definition information is out of phase with the signal of the center portion, and the image quality is degraded.

[0009]

When the SN ratio is deteriorated or a ghost component is present on the receiving side, or when the VTR
However, there is a problem that the image quality deteriorates when the high-definition information originally inserted to improve the image quality is added to the video signal in the case of reproducing from.

An object of the present invention is to provide an image quality improving circuit which prevents deterioration of image quality caused by high definition information.

[0011]

The means according to the present invention comprises a second video signal reproducible from a first video signal by a current-type image receiver.
Of the high-definition information based on the first video signal, the second reproduction means for reproducing the high-definition information from the first video signal, and the information of the high-definition information based on the first video signal. It comprises a control means for controlling the amount and a multiplexing means for multiplexing the output of the first reproducing means and the output of the control means.

[0012]

With the above-mentioned means, the control means detects the state of the first video signal and controls the information amount of the high-definition information in accordance with the detection result, thereby preventing the deterioration of the image quality caused by the high-definition information. Get off.

[0013]

First, before explaining an embodiment of the present invention,
The overall configuration will be described. FIG. 4 is a diagram showing the configuration of a transmission / reception system based on the letterbox method. In the figure, an aspect ratio of 16: 9, a number of scanning lines of 525, and a progressive scanning video signal (16: 9, 525, 1: 1 video signal) are transmitted through a terminal 30 to a center processing circuit 31 and high-definition information processing. And the circuit 32. The center processing circuit 31 performs vertical band limitation so that vertical folding components are not noticeable in the receiver of the current system, and is compressed in the vertical direction and then converted into an interlaced signal. The compression ratio is 3/4. This has an aspect ratio of 16: 9 even with current receivers.
This is so that the screen of can be seen. Therefore, FIG.
If the number of effective scanning lines is 480, as shown in (3), the number of scanning lines is 360 when the aspect ratio is 16: 9. This signal is supplied to the multiplexing circuit 33.

On the other hand, in the high-definition information processing unit 32, the vertical high band component lost due to the vertical band limitation of the center processing circuit 31 or the horizontal high band component exceeding 4.2 MHz is band-compressed, time-compressed or frequency-converted. It is processed. As a result, the multiplexing circuit 33 causes the center processing circuit 31 to
It becomes possible to effectively multiplex the output of. Multiplex circuit 3
In 3, the output of the center processing circuit 31 and the output of the high definition information processing unit 32 are multiplexed. As the multiple area, in addition to the masked portion, which is the shaded area in FIG. 5, the conjugate hole (commonly called blow hole) of the color subcarrier shown in FIG. 6A, a horizontal overscan portion as shown in FIG. A method of multiplexing the quadrature component of the modulated center signal has also been considered. Then, in order to distinguish it from a normal NTSC signal, an identification signal is inserted in a part of the upper and lower mask portions shown by hatching in FIG. The multiplexed signal is supplied to the transmission circuit 34, modulated into an RF signal, and then transmitted from the antenna 35.

The transmitted RF signal is supplied to the receiving circuit 37 via the antenna 36. The output signal of the receiving circuit 37 is supplied to the image quality improving circuit 38, and after being subjected to center reproduction processing and high-definition information reproduction processing, it is supplied to the monitor 39 and displayed.

Embodiments according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing the configuration of a first embodiment according to the present invention. The video signal containing high-definition information, which is the output of the receiving circuit 37, is supplied to the separation circuit 11 and the control circuit 17 via the terminal 10. The video signal is separated in the separation circuit 11 and supplied to the center reproduction circuit 12 and the high-definition information reproduction circuit 13. In the center reproducing circuit 12, the interlaced signal is converted into a progressive scanning signal and then vertically expanded to reproduce a video signal of 16: 9.525.1: 1 and supply it to the adder 15. The high-definition information reproducing circuit 13 reproduces various kinds of high-definition information and supplies it to the coefficient unit 14.

On the other hand, the control circuit 17 detects the SN ratio of the supplied video signal, and based on this SN ratio, the coefficient unit 14
A control signal for controlling is output. A coefficient K (0 ≦ K ≦ 1) is determined in the coefficient unit 14 based on the control signal, and the coefficient K is supplied to the adder 15 after being multiplied by the high definition information. In the adder 15, the output of the center reproduction circuit 12 is 1
The output of the coefficient unit 14 is added to the video signal of 6: 9.525.1: 1 and supplied to the monitor 16. Then, a 16: 9, 525, 1: 1 image containing high-definition information K times is displayed.

With such a configuration, the amount of high-definition information added to the video signal of the center portion can be controlled according to the deterioration situation of the SN ratio, and the image quality deterioration due to the high-definition information can be prevented. ..

Next, a second embodiment according to the present invention will be described with reference to FIG. In FIG. 2, the video signal output from the receiving circuit 37 is transmitted through the terminal 10 to the ghost canceller 18
Is supplied to. GCR (gh
The ghost state is detected and the ghost component is removed based on a reference signal such as an ost canceller reference signal. The output of the ghost canceller 18 is separated by the separation circuit 11, and the center detection circuit 12 and the high-definition information reproduction circuit 1 are separated.
3 and 3 are supplied. In the center reproducing circuit 12, the interlaced signal is converted into a progressive scanning signal and then vertically expanded to reproduce a video signal of 16: 9.525.1: 1 and supply it to the adder 15. The high-definition information reproducing circuit 13 reproduces various kinds of high-definition information, and the coefficient unit 1
4 is supplied.

On the other hand, the removal condition of the ghost component is supplied to the memory circuit 19, and the coefficient unit 14 is based on this removal condition.
A control signal for controlling is output. A coefficient K (0 ≦ K ≦ 1) is determined in the coefficient unit 14 based on the control signal, and the coefficient K is supplied to the adder 15 after being multiplied by the high definition information. In the adder 15, the output of the center reproduction circuit 12 is 1
The output of the coefficient unit 14 is added to the video signal of 6: 9.525.1: 1 and supplied to the monitor 16. Then, a 16: 9, 525, 1: 1 image containing high-definition information K times is displayed.

The ghost cancellers currently on the market are 10 for front ghosts and 10 rear ghosts, respectively.
It is possible to detect μs and 50 μs. However, due to cost constraints and the like, the range in which the ghost component can be actually removed is about 4 μs for the front ghost and about 40 μs for the rear ghost. Therefore, if there is a large ghost component outside the removable range, it cannot be removed even if it can be detected.

In such a case, since the ghost is also included in the high-definition information, the amount of the high-definition information added to the video signal at the center can be reduced by reducing the coefficient K, and the high-definition information can be reduced. It is possible to prevent deterioration of image quality due to.

Most of the ghost components differ in the degree depending on the channel. Some ghost components may not be detected, for example, when the number of adjacent ghosts is very large. Therefore, an undetectable ghost channel is written in the memory circuit 19 in advance, and when the corresponding channel is selected, the coefficient value of the coefficient unit 14 is controlled so as to be close to “0”, thereby deteriorating the image quality. Can be prevented.

Next, a third embodiment according to the present invention will be described with reference to FIG. 3 is different from FIG. 1 in that the control circuit 17 is replaced by the non-standard signal detection circuit 17, and the other configuration is the same as that of the first embodiment.

The non-standard signal detection circuit 17 is a circuit for detecting whether the video signal supplied through the terminal 10 is a standard signal or a non-standard signal. The non-standard signal is a signal in which the relationship between the vertical sync, the horizontal sync and the color subcarrier is broken. For example, in the case of once recording and reproducing with a home VTR, the relationship between the vertical synchronization, the horizontal synchronization and the color subcarrier is broken due to the influence of jitter or the like. When such a non-standard signal is supplied, the non-standard signal detection circuit 17 supplies the coefficient unit 14 with
A control signal for setting the coefficient K to "0" is output. As a result, it is possible to prevent the deterioration of the image quality due to the high-definition information, which is caused by the fact that the high-definition information is not accurately reproduced or the phase of the signal of the center portion is shifted.

As described above, the image quality generated by the high-definition information is obtained by detecting the deterioration of the SN ratio, the ghost elimination situation, and the non-standard signal, and changing the coefficient K of the coefficient unit 14 according to these situations. Can be prevented from deteriorating.
Although the configurations of the embodiments have been described individually, the configurations may be combined with each other.

[0027]

As described above, the deterioration of the SN ratio, the ghost elimination status, and the non-standard signal are detected, and the proportion of the high-definition information to be added to the video signal is changed according to these statuses, thereby changing the high-definition information. It is possible to prevent the deterioration of the image quality caused by.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of a first embodiment according to the present invention.

FIG. 2 is a configuration diagram showing a configuration of a second embodiment according to the present invention.

FIG. 3 is a configuration diagram showing a configuration of a third embodiment according to the present invention.

FIG. 4 is a configuration diagram showing an overall configuration of the present invention.

FIG. 5 is an explanatory diagram illustrating a configuration of a wide screen.

FIG. 6 is an explanatory diagram illustrating a multiple area of high-definition information.

FIG. 7 is a configuration diagram showing a conventional configuration.

[Explanation of symbols]

11 ... Separation circuit, 12 ... Center reproduction circuit, 13 ... High-definition information reproduction circuit, 14 ... Coefficient multiplier, 15 ... Adder, 16
... monitor, 17 ... control circuit.

Claims (1)

[Claims] 1. A first reproducing means for reproducing a second video signal which can be reproduced by a current-system image receiver from the first video signal, and a high-definition information reproducing means for reproducing high-definition information from the first video signal. 2 reproduction means, control means for controlling the information amount of the high definition information based on the first video signal, and multiplexing for multiplexing the output of the first reproduction means and the output of the control means. An image quality improvement circuit comprising: