JPH08111853A - Multiplex signal reproducing device - Google Patents

Abstract

PURPOSE: To attain the reproduction of a level only for a part where a vertical reinforcement signal is multiplexed by evading mis-detection of a correlation signal. CONSTITUTION: A television signal whose level is reduced is received for a part where a multiplex signal used to reinforce a vertical high frequency component of a video signal has a correlation with the video signal. A subtractor 310 and a line memory 300 extract the vertical high frequency component and uses it to detect a part having correlation by means of a line memory 210, a field memory 220 and subtractors 230, 240 and a multiplier 290 decodes a level of the multiplexed signal based on the result of the detection signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex signal processing apparatus for a wide aspect TV system compatible with current broadcasting, and more particularly to improving image quality deterioration due to S / N deterioration.

[0002]

2. Description of the Related Art A wide aspect TV system compatible with current broadcasting is proposed in Japanese Patent Application No. 5-290828, "Television signal processing device". In such a wide aspect TV system by letterbox processing, a method of multiplexing vertical reinforcement signals in upper and lower non-picture areas is being studied. However, at this time, the signals multiplexed in the upper and lower non-image parts are detected as interference by the current receiver, and therefore a method of lowering the level of the multiplexed signal for transmission is necessary.

As a means for reducing interference of multiple signals, it is disclosed in Japanese Patent Application No. 1-144947, "Multiple signal transmitting apparatus and multiple signal receiving apparatus", in which the correlation with the multiple signals is detected from the main signal and the level is detected. Techniques for limiting have been proposed. Here, since the multiplexed vertical reinforcement signal is a vertical high-frequency signal that is not transmitted by the main signal, the correlation signal virtually separates the vertical high-frequency component from the main signal. However, since the main signal is transmitted in the interlaced structure, the vertical high frequency component and the time direction high frequency component are mixed in the same region. That is, with the interlaced structure, even in a still image, a horizontal line (vertical high-frequency component) is detected as a temporal high-frequency component (in this part, the vertical high-frequency component needs to be reinforced). ). However, the conventional detection method detects even signal components that do not correlate with the original multiplex signal (for example, an image in which a vertical line is moving horizontally), and the level control function works to perform transmission. Will be seen.

Normally, even on the transmitter side, in the multiplex signal processing system, the level of the area originally free from multiplex signals is reduced, so that no problem occurs. However, if S / N deterioration occurs in the transmission path, the receiver side will perform level improvement processing even in the area where there is no multiplex signal, so only the noise component will be emphasized. There is a problem that becomes an obstacle. This problem will be described below with reference to the drawings.

FIG. 6A shows an example of the interference reducing circuit on the transmitting side. The main signal Y is a low pass filter (LPF) 100.
And the horizontal low frequency component is separated. LPF10
The output of 0 is input to the line memory 110 and delayed by one line period. The output of the line memory 110 is input to the field memory 120 and delayed for 262H. The output of the LPF 100 and the output of the line memory 110 are input to subtractors 130 and 140, respectively, and subjected to subtraction processing with the output of the field memory 120. Subtractor 130,
The output of 140 is input to absolute value circuits 150 and 160, respectively, and becomes an absolute value output. Absolute value circuit 150, 16
The output of 0 is input to the adder 170 and added. The output of the adder 170 is input to the coefficient generation circuit 180, and the coefficient value is increased when the input level is high and is decreased when the input level is low. However, the limit is set so that it does not exceed the threshold when the input level is high or low. On the other hand, the vertical reinforcement signal is input to the divider 190 and divided by the output of the coefficient generator 180.

FIG. 6 (b) shows an example of signal waveforms at each part. As can be seen from A, B, and C, an image in which a vertical line is moving is shown on the left side, and an image containing a vertical high-frequency component of a still image is shown on the right side. As shown in the figure, in the correlation signal D, a component having a high correlation is extracted in both cases. Therefore, in the coefficient E, a portion where the level of the vertical reinforcement signal is reduced occurs on both the left and right sides. However, in this case, since the actual vertical reinforcement signal exists only in the right image and there is originally no reinforcement signal on the left side, there is no signal level fluctuation in the left side image. On the right side, the level of the vertical reinforcement component is limited and held low.

FIG. 7A shows an example of the interference reduction reproducing circuit on the receiver side. In the main signal Y, the LPF 200 separates only horizontal low-frequency components. The output of the LPF 200 is input to the line memory 210 and delayed by one line period. The output of the line memory 210 is input to the field memory 220 and delayed for 262H. The output of the LPF 200 and the output of the line memory 210 are the subtractor 23, respectively.
0 and 240, and the subtraction processing is performed with the output of the field memory 220. The outputs of the subtracters 230 and 240 are input to the absolute value circuits 250 and 260, respectively, and become absolute value outputs. The outputs of the absolute value circuits 250 and 260 are added by the adder 27.
It is input to 0 and added. The output of the adder 270 is input to the coefficient generation circuit 280, and the coefficient value is increased when the input level is high and is decreased when the input level is low. However, the limit is set so that it does not exceed the threshold when the input level is high or low. On the other hand, the vertical reinforcement signal is input to the multiplier 290, multiplied by the output of the coefficient generator 280, and reproduced to the original signal level.

FIG. 8B shows the signal waveform of each part in the receiver. Here, the case where the received S / N of the input signal is deteriorated is shown. Since the noise component of the main signal Y is removed by the LPF 200, the noise is reduced from A to E, and the noise level of the multiplexed signal is emphasized in the reproducing circuit. Since the correlation signal D is detected on the receiver side similarly to the transmitter side, the correlation signal is similarly detected on each of the left and right images, and the coefficient value is generated so as to improve the level (the amount reduced by the transmission side). To return to the original level). However, at the time of S / N deterioration, there is no reinforcement signal in the image on the left side, and there is only noise, so noise is partially emphasized as shown in G. Also,
Noise is partially emphasized in the image on the right side, but the noise is generally not noticeable because the vertical reinforcement signal is a vertical high frequency component. Therefore, when a vertical line is moving as in the image on the left side, a pseudo correlation signal with the vertical reinforcement signal is generated, and if the S / N is degraded on the receiver side, noise is generated. Is increased, and it becomes noticeable, which causes a problem of image quality deterioration.

As a countermeasure against image quality deterioration due to reproduction of multiple signals in such S / N deterioration, a method of controlling so as not to reproduce the multiple signals when S / N is deteriorated has been proposed (Japanese Patent Laid-Open No. 4-252688 "scanning line". Conversion circuit "). However, since such interference is a trade-off between the effects of the input signal S / N and the multiplex signal, it is often the case that the multiplex signal is not reproduced in ordinary households by simply stopping the reproduction of the multiplex signal. There is a risk that the receiver will lose its meaning as a receiver.

[0010]

As described above,
In the level reduction processing of the vertical reinforcement signal to be multiplexed in the upper and lower non-picture portions, even when the received S / N is deteriorated, the pseudo correlation signal detected by the level reproduction processing of the reinforcement signal is not even multiplexed in the vertical reinforcement signal. When it occurs, there is a problem that the noise component is lifted and the image quality is deteriorated.

Therefore, an object of the present invention is to provide a multiple signal reproducing apparatus which improves erroneous detection of a correlation signal, which is a problem, and performs level reproduction only in a portion where a vertical reinforcement signal is multiplexed. . That is, S / on the receiving side
An object of the present invention is to provide a multiplex signal reproducing device which reproduces a multiplex signal level without any noticeable noise enhancement even when N is deteriorated.

[0012]

According to the present invention, it is necessary not to detect a correlation signal in an image such as horizontal panning of vertical lines which is erroneously detected in correlation detection. Therefore, a circuit for detecting the vertical line of the image is provided so that the image having the vertical line is not subjected to the correlation detection. As means for that purpose, a means for removing a vertical line component using the first vertical high-pass filter, and a means for detecting a horizontal edge and stopping the correlation detection circuit at the horizontal edge are used as a second means. Further, since it causes a problem when the received S / N originally deteriorates, a means for detecting the S / N and correcting the levels of the multiplexed signal and the coefficient output according to the noise amount is used.

[0013]

With the above means, the first and second means can eliminate or detect the panning image of the vertical line, which is the cause of the generation of the pseudo correlation signal, and prevent the pseudo correlation signal from being generated. In the third means, the level enhancement processing is performed on the vertical reinforcement signal and the coefficient signal by the reception S / N, so that the image quality can be improved and noise can be prevented.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. FIG.
In (a), the main signal Y is delayed by one horizontal scanning period in the line memory 300, subtracted from the main signal Y in the subtractor 310, and output. The output of the subtractor 310 is LPF2
00, and only the horizontal low frequency component is separated. LPF
The output of 200 is input to the line memory 210 and delayed by one line period. The output of the line memory 210 is input to the field memory 220 and delayed for 262H. The output of the LPF 200 and the output of the line memory 210 are input to subtractors 230 and 240, respectively, and subjected to subtraction processing with the output of the field memory 220. Subtractor 23
The outputs of 0 and 240 are absolute value circuits 250 and 26, respectively.
It is input to 0 and becomes an absolute value output. Absolute value circuit 250, 2
The output of 60 is input to the adder 270 and added.
The output of the adder 270 is input to the coefficient generation circuit 280, and the coefficient value is increased when the input level is high and is decreased when the input level is low. However, it is restricted so that it does not exceed the threshold when the input level is high or low. On the other hand, the vertical reinforcement signal is input to the multiplier 290, multiplied by the output of the coefficient generator 280, and reproduced to the original signal level.

In the present embodiment, a one-line difference circuit for the main signal Y is inserted in the preceding stage of the circuit of the conventional example to form a vertical high pass filter. FIG. 1B shows a waveform diagram of each part. By the action of the vertical high-pass filter, the horizontal edge of the Y signal on the left side is removed and the correlated right side component is output as it is. Therefore, as shown in E, since the false detection component does not occur in the correlation detection signal as in the conventional case, the reproduction vertical reinforcement signal shown in G does not cause S / N deterioration in the flat portion.

FIG. 2 shows a second embodiment of the present invention. In FIG. 2A, the main signal Y is input to the edge detection circuit 320, the edge detection circuit 320 detects a horizontal edge, and outputs the edge detection signal H. The main signal Y is L
It is input to the PF 200 and only the horizontal low frequency component is separated. L
The output of the PF 200 is input to the line memory 210,
It is delayed by one line period. The output of the line memory 210 is input to the field memory 220 and delayed for 262H. Output of LPF 200 and line memory 210
Is output to the subtracters 230 and 240 respectively,
The subtraction process is performed with the output of the field memory 220. The outputs of the subtracters 230 and 240 are the absolute value circuit 25, respectively.
It is input to 0, 260 and becomes an absolute value output. Absolute value circuit 2
The outputs of 50 and 260 are input to the adder 270 and added. The output of the adder 270 and the edge detection output are input to the coefficient generation circuit 280, and when the edge is detected, the coefficient value is reduced, and when there is no edge, the adder 27 is used.
According to the output of 0, the coefficient value is increased when the level is high, and the coefficient value is decreased when the level is low. However,
Limit the threshold so that it does not exceed the threshold when the input level is high or low. On the other hand, the vertical reinforcement signal is input to the multiplier 290, multiplied by the output of the coefficient generator 280, and reproduced to the original signal level.

As can be seen from the waveform diagram of FIG. 2B, the edge detection signal H is expanded in the horizontal direction, and the coefficient signal E is controlled in accordance with this signal, so that the moving vertical line shown on the left side Since the coefficient value is small, noise is not emphasized in the vertical reinforcement signal output shown in G.

FIG. 3 shows a third embodiment. Here, an improvement method of control using noise detection is shown. In the conventional example, when the reception S / N is deteriorated, the reproduction and addition of the multiplex signal are simply stopped, so that there is a problem that the image quality improving effect by the multiplex signal is completely lost. Therefore, here, a method of variably controlling the multiple signal addition level according to the received S / N is used. The video signal is input to the noise detection circuit 330, the received S / N of the image is detected, and when the received S / N is equal to or more than the threshold value, the noise determination signal is output. Further, the main signal Y is input to the LPF 200 and separates only the horizontal low frequency component. The output of the LPF 200 is input to the line memory 210 and delayed by one line period. The output of the line memory 210 is input to the field memory 220 and delayed for 262H. LPF
The output of 200 and the output of the line memory 210 are input to the subtractors 230 and 240, respectively, and the field memory 2
20 output and subtracted. The outputs of the subtracters 230 and 240 are input to the absolute value circuits 250 and 260, respectively, and become absolute value outputs. The outputs of the absolute value circuits 250 and 260 are input to the adder 270 and added.

The output of the adder 270 and the noise determination signal are
The coefficient value is input to the coefficient generation circuit 280, and when the received S / N is bad, the coefficient value is reduced, and when the received S / N is good, the coefficient value is set according to the output of the adder 270 when the level is large. If it is small, the coefficient value is also small when it is small. However, it is restricted so that it does not exceed the threshold when the input level is high or low. On the other hand, the vertical reinforcement signal is input to the multiplier 290, multiplied by the output of the coefficient generator 280, and reproduced to the original signal level. FIG.
In the waveform diagram of (b), the case where the received S / N is bad is shown as an example. As shown in E, when the S / N is deteriorated, the value of the coefficient value is reduced to suppress the level reproduction effect, thereby suppressing an extreme noise level difference as shown in G. You can In this case, since the enhancement signal level reproduction is compatible to some extent, the image quality improvement due to the multiple signals can be expected. Further, it is not necessary to switch the reception S / N only by one threshold value, and if the S / N is detected stepwise, the level of the coefficient value can be changed according to the S / N level, and the level reproduction can be performed. The effect and noise reinforcement can be set as a trade-off.

FIGS. 4A and 4B show still another embodiment of the present invention. The circuit of FIG. 4 (a) is
It is another example of using edge detection. By limiting the input of the main signal Y input to the correlation detection according to the edge detection signal, the same effect as the circuit of FIG. 2 can be obtained.

That is, the main signal Y is the edge detection circuit 320.
Is supplied to the switch 340. The output of the switch 340 is supplied to the LPF 200. The subsequent structure is the same as that of the embodiment shown in FIG. When an edge is detected, the switch 340 is turned off during the edge period and the input of the main signal Y to the correlation detection unit is limited.

FIG. 4B shows another example using noise detection. Here, the noise determination signal obtained from the noise detection circuit 330 that detects the noise of the main signal and the vertical reinforcement signal before level reproduction are input to the non-linear circuit 350, and received S
By switching the non-linear characteristic according to / N, the same effect as the embodiment of FIG. 3 can be obtained. Non-linear circuit 3
The output of 50 is input to the multiplier 290. The other structure is the same as that of the embodiment of FIG.

FIG. 5 shows a characteristic example of the non-linear circuit 330 at this time. In this example, when the received S / N is good, the output is linear, and when the received S / N is deteriorated, the output level is limited by the nonlinear characteristic that further attenuates the low-level input signal to reduce the noise component. It is a thing.

[0024]

As described above, according to the present invention, the erroneous detection of the correlation signal is improved, the level reproduction is performed only in the portion where the vertical reinforcement signal is multiplexed, and the S / N deterioration at the receiving side causes a visual error. It is possible to reproduce the multiple signal level by suppressing the attached noise without enhancing it.

[Brief description of drawings]

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

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

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

FIG. 4 is a diagram showing fourth and fifth embodiments of the present invention.

FIG. 5 is a diagram showing characteristics of a non-linear circuit in the fifth embodiment.

FIG. 6 is a diagram showing a conventional level control circuit for multiplexed signals on the transmission side.

FIG. 7 is a diagram showing a conventional multiple signal level reproduction circuit.

[Explanation of symbols]

200 ... Low-pass filter (LPF), 210 ... Line memory, 220 ... Field memory, 230, 240 ...
Subtractor, 250, 260 ... Absolute value circuit, 270 ... Adder, 280 ... Coefficient generating circuit, 290 ... Multiplier, 300 ...
Line memory, 310 ... Subtractor, 320 ... Edge detection circuit, 330 ... Noise detection circuit, 530 ... Non-linear circuit.

Claims (8)

[Claims] 1. When transmitting a video signal and a multiplex signal for reinforcing a vertical high frequency component of the video signal, the level of the multiplex signal is set at a portion where the video signal and the multiplex signal have a correlation. In a receiving device that receives a television signal from a transmitting means that adaptively reduces and transmits, a vertical high-pass filter that extracts a vertical high-frequency component of the received video signal, and the video using the output of the vertical high-pass filter Correlation detection means for detecting the correlated portion of the signal, and level reproduction means for receiving the received multiplex signal and restoring the level of the multiplex signal based on the detection signal from the correlation detection means Multiple signal reproduction device. 2. When transmitting a video signal and a multiplexed signal for reinforcing a vertical high frequency component of the video signal, the level of the multiplexed signal is set at a portion where the video signal and the multiplexed signal have a correlation. In a receiving device that receives a television signal from a transmitting unit that adaptively reduces and transmits, a level reproducing unit that restores the level of the received multiplex signal based on a level control signal, and the level of the received video signal. Correlation detection means for detecting a correlated portion to obtain a correlation detection signal, edge detection means for detecting a horizontal edge component of the received video signal to obtain an edge detection signal, the edge detection signal and the correlation detection A coefficient that is controlled by a signal and switches the characteristic of outputting the level control signal based on the correlation detection signal, depending on whether there is an edge detection signal or not. A multiple signal reproducing apparatus comprising: a generating unit. 3. When transmitting a video signal and a multiplexed signal for reinforcing a vertical high frequency component of the video signal, the level of the multiplexed signal is set at a portion where the video signal and the multiplexed signal have a correlation. In a receiving device that receives a television signal from a transmitting unit that adaptively reduces and transmits, a level reproducing unit that restores the level of the received multiplex signal based on a level control signal, and the level of the received video signal. Correlation detection means for obtaining a correlation detection signal by detecting a correlative portion, noise detection means for detecting a noise component of the received video signal to obtain a noise detection signal, the noise detection signal and the correlation detection signal The coefficient generation for switching the characteristic of outputting the level control signal based on the correlation detection signal, depending on whether there is a noise detection signal or not. A multi-signal reproducing apparatus comprising: 4. When transmitting a video signal and a multiplexed signal for reinforcing a vertical high frequency component of the video signal, the level of the multiplexed signal is set at a portion where the video signal and the multiplexed signal have a correlation. In a receiving device for receiving a television signal from a transmitting means that adaptively reduces and transmits, a level reproducing means for restoring the level of the received multiple signal based on a level control signal, and a horizontal signal for the received video signal. An edge detecting means for detecting an edge component to obtain an edge detecting signal; and when the edge detecting signal detects an edge, the input of the received video signal is stepped, and when the edge is not detected, it is received. Correlation detection means for introducing the video signal, detecting the correlated portion of the received video signal, and obtaining a correlation detection signal, and based on the correlation detection signal And a coefficient generating means for outputting the level control signal. 5. When transmitting a video signal and a multiplexed signal for reinforcing a vertical high frequency component of the video signal, the level of the multiplexed signal is set at a portion where the video signal and the multiplexed signal have a correlation. In a receiving device that receives a television signal from a transmitting unit that adaptively reduces and transmits, a correlation detecting unit that detects the correlated portion of the received video signal and obtains a correlation detection signal, Coefficient generating means for outputting a level control signal based on a correlation detection signal, noise detecting means for detecting a noise component of the received video signal to obtain a noise detection signal, and the received multiplexing according to the noise detection signal. Non-linear circuit means for controlling and outputting the level of the signal, and the multiplex signal output from the non-linear circuit means are supplied, and the multiplex signal is generated based on the level control signal. Multiplexed signal reproducing apparatus characterized by comprising a level playing means for restoring the level. 6. The multiple signal reproducing apparatus according to claim 3, wherein the noise detecting means detects a reception S / N. 7. The multiple signal reproducing apparatus according to claim 5, wherein said non-linear circuit means has a plurality of non-linear characteristics. 8. When transmitting a video signal and a multiplexed signal for reinforcing a vertical high frequency component of the video signal, the level of the multiplexed signal is set at a portion where the video signal and the multiplexed signal have a correlation. In a receiving device that receives a television signal from a transmitting means that adaptively reduces and transmits, a vertical high-pass filter that extracts a vertical high-frequency component of the received video signal, and the video using the output of the vertical high-pass filter Correlation detection means for detecting the correlating portion of the signal, and the level reproduction means for inputting the received multiplex signal and for restoring the level of the multiplex signal based on the detection signal from the correlation detection means And a noise detection unit that obtains a noise detection signal by detecting a noise component of the video signal, the vertical high-pass filter according to the noise detection signal. The filter characteristic is switched, and the filter characteristic is changed.
The multiplex signal reproduction device described.