JPH10341416A - Video signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase of a circuit scale without changing characteristics in the case of dividing the inter-frame difference signals of the HDTV signals of a MUSE system into a high band including return components and a low band not including the return components and processing them. SOLUTION: Low-pass filters 9 and 10 are cascade connected, and the output of the cascade connection of the low-pass filters 9 and 10 and the output between the stages of the low-pass filter 9 and the low-pass filter 10 are subtracted in a subtraction circuit 11. The low-pass filter 9 is to be provided with the characteristic of passing through the area of the transmission band of MUSE signals and the low-pass filter 10 is to be provided with to the characteristic of passing through an area corresponding to the low band part of the MUSE signals not including the return components. By the cascade connection of the low-pass filters 9 and 10, the components of the area corresponding to the low band part of the inter-frame difference signal of the MUSE signals are extracted and the high band components are extracted by the output of the subtraction circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to MUSE (Mult
The present invention relates to a video signal processing device suitable for use in an iple Sub-Nyquist Sampling Encoding decoder.
The present invention relates to a video signal processing device suitable for use in noise reduction and motion detection of a USE decoder.

[0002]

2. Description of the Related Art HDTV (High Definition Televisio)
n) As a signal transmission method, MUSE (Multiple Sub-Ny
quist Sampling Encoding) method is known. MU
The SE system compresses high-definition television signals using a sub-sampling technique.

That is, an HDTV signal has one scanning line.
125 lines, the field frequency is 60 Hz, and the scanning is interlaced. Therefore, its bandwidth is about 20
MHz, which is the current television broadcast band (about 4M
Hz). Therefore, the HDTV signal is
It is difficult to transmit as it is.

In the MUSE system, the number of pixels on one screen is 1/4.
Is thinned out. Then, as shown in FIG. 15, in the first field, the pixel at the position indicated by a white circle is transmitted, in the next field, the pixel at the position indicated by a white square is transmitted, and in the next field, the pixel at the position indicated by a black circle is transmitted. Pixels are transmitted,
In the next field, the pixel at the position indicated by the black angle is transmitted. At the time of reception, images for four fields are stored in the memory. Then, using the image data of 4 fields,
One screen is formed. Thus, in the MUSE system,
In the still image portion, one screen is thinned out to １ ／ by changing the phase every four fields. Thereby, the HDTV signal can be compressed to about 8 MHz.

As described above, in the MUSE system, since the HDTV signal is sub-sampled and transmitted, the high-frequency component includes a folded component. Therefore, MUSE
In the case of processing an HDTV signal of a system, it may be necessary to perform different processing for a high-frequency component including a folded component and a low-frequency component not including a folded component.

That is, in the MUSE system, 48.6 MH
z is the original sampling frequency. FIG.
This shows the spectrum at this time, and in the figure, the horizontal axis indicates frequency, and the vertical axis indicates level. The original sampling frequency is 48.6 MHz, whereas the band of the MUSE HDTV signal is about 20 MHz.
And the band of the MUSE HDTV signal is equal to or less than 1/2 of the original sampling frequency. For this reason, no aliasing distortion has occurred.

The MUSE video signal having the original sampling frequency is thinned out by inter-field offset sampling, and the sampling frequency is 24.3 MHz.
Is sub-sampled. When sub-sampling is performed at a frequency of 24.3 MHz, aliasing occurs in a component having a frequency of 12.15 MHz or higher. FIG. 16B shows the spectrum at this time. As shown in FIG. 16B, aliasing occurs at a frequency of 12.15 MHz or less by sub-sampling at a frequency of 24.3 MHz.

[0008] The signal subsampled at this frequency of 24.5 MHz is further converted to a sampling frequency of 32.4 MHz in preparation for the next inter-frame offset. Then, it is thinned out by inter-frame offset sampling, and is sub-sampled at a frequency of 16.2 MHz. When sub-sampling is performed at a frequency of 16.2 MHz, aliasing occurs in a component having a frequency of 8.1 MHz or higher. FIG. 16C shows the spectrum at this time. As shown in FIG. 16C, the frequency is 16.2 MHz.
Sub-sampling occurs at a frequency of 8.1 MHz.

The spectrum shown in FIG. 16C is the spectrum of the MUSE HDTV signal. As shown in FIG. 16C, the MUSE HDTV signal is
It contains components up to a frequency of 8.1 MHz, of which high-frequency components at a frequency of 4.05 MHz or more include aliasing components.

For example, a noise reducer can be configured by subtracting the difference between the image data of one frame from the main line signal. However, in the MUSE system, since the sampling phase differs between consecutive frames, a difference between one frame cannot be obtained as it is. Therefore, it is conceivable to interpolate the pixels so that the sampling phase matches, and obtain a difference in image data between one frame.

However, pixels can be interpolated only with respect to the low-frequency component that does not include the aliasing component, and the high-frequency component includes the aliasing component. Cannot be detected.

Further, the MUSE decoder is provided with a motion detecting circuit. In order to cope with the fast motion, it is conceivable to perform motion detection based on the difference of image data between one frame. However, in the MUSE method, the sampling phase differs between consecutive frames.
The difference between one frame cannot be obtained as it is. Interpolate the pixels so that the sampling phase matches,
Although it is conceivable to perform motion detection based on a difference in image data between one frame, since a high-frequency component includes a folded component, it is necessary to detect a difference in image data between one frame in this way. Can not.

As described above, when a difference between one frame of the MUSE HDTV signal is detected to constitute a noise reducer or a motion detection circuit, a low-frequency component having no aliasing component and an aliasing component are included. It is necessary to perform different processing on the high-frequency components including For this reason, conventionally, a circuit for detecting a difference signal between one frame includes a low-pass filter for extracting a low-frequency component containing no aliasing component and a band-pass filter for extracting a high-frequency component including aliasing component. It is provided.

That is, in FIG.
1 is supplied with a MUSE HDTV signal. The MUSE HDTV signal from the input terminal 101 is supplied to one terminal 102A of the switch circuit 102 and is also supplied to one terminal 103A of the switch circuit 103 via the delay circuit 104 having a delay amount of two fields. Is done. The other terminal 102B of the switch circuit 102 and the other terminal 103B of the switch circuit 103 are grounded.

A sub-sample pulse is supplied to a terminal 105. This sub-sample pulse is supplied to the inverter 10
6 and to the switch circuit 103 as well as to the switch circuit 102. The switch circuits 102 and 103 are alternately switched in the opposite directions based on the sub-sample pulse from the terminal 105.
The switch circuits 102 and 103 are respectively connected to a terminal 102A
When the terminal is set to the terminals 102B and 103B, data of "0" is output.

Switch circuit 102 and switch circuit 10
3 is supplied to the subtraction circuit 107. Subtraction circuit 10
7, the MUSE HDTV signal of the current field from the input terminal 101 via the switch circuit 102;
From input terminal 101, delay circuit 104, switch circuit 1
03 MUSE HDT two fields before
The V signal is subtracted. Thus, a difference signal between one frame of the MUSE HDTV signal is obtained from the output of the subtraction circuit 107.

In the MUSE system, image data at different positions are sent in a 4-field cycle, and the difference cannot be obtained as it is. Therefore, the switch circuits 102 and 1 are set so that the difference between one frame is obtained.
03, the data of “0” is inserted. As described above, when data “0” is inserted between pixels in each field, the overall gain becomes １ ／. Therefore, in order to compensate for a decrease in gain caused by inserting data “0” between pixels by the switch circuits 102 and 103,
A gain amplifier 108 is provided.

The output of the subtraction circuit 107 is
8 is supplied. The gain amplifier 108 provides a double gain. The output of the gain amplifier 108 is supplied to a band-pass filter 109 and also to a low-pass filter 110.

The band-pass filter 109 has a characteristic of passing a high-frequency component containing a folded component of the MUSE HDTV signal. In the MUSE system, the transmission band is set to 8.1 MHz, and a folded component is included at a frequency of 4.05 MHz or more. Therefore, as shown in FIG. 18B, the bandpass filter 109 has a characteristic of passing a frequency of 4.05 MHz to 8.1 MHz.

The low-pass filter 110 has the characteristic of passing low-frequency components that do not contain aliasing components. In the MUSE system, no aliasing component is included in the frequency of 4.05 MHz or less. For this reason, as shown in FIG.
The frequency is set to pass through the frequency of 05 MHz or less.

From the bandpass filter 109, the MUS
The high-frequency component of the one-frame difference signal of the E-system HDTV signal is output, and this output is output from the output terminal 111. From the low-pass filter 110, the MUSE H
The low-frequency component of the one-frame difference signal of the DTV signal is output.
12 is output.

[0022]

As described above, conventionally, a band-pass filter 109 for extracting high-frequency components including aliasing components and a low-pass filter 110 for extracting low-frequency components not including aliasing components are conventionally used. Are provided respectively. However, this causes a problem that the circuit scale increases.

That is, the band-pass filter 109 and the low-pass filter 110 are, for example, FIR (Finite Imp
ulse Response) filter. In the FIR filter, as the number of taps increases, steep characteristics are obtained, but the circuit scale increases accordingly. Conventionally, the band-pass filter 109 is configured by, for example, a 17-tap FIR filter, and the low-pass filter 110 is configured by, for example, a 17-tap FIR filter. Thus, 2
Since an FIR filter with 17 taps is required, the circuit scale is increasing.

Therefore, an object of the present invention is to provide a MUSE
In the case where the inter-frame difference signal of the HDTV signal of the CDMA system is divided into a high band including the aliasing component and a low band including no aliasing component, the circuit scale can be prevented from increasing without changing the characteristics. To provide a video signal processing device.

[0025]

SUMMARY OF THE INVENTION According to the present invention, a video signal in which a difference signal between frames of an HDTV video signal which is sub-sampled and transmitted is divided into a low-frequency part and a high-frequency part and each of the extracted signals is extracted. In a signal processing device, cascaded first and second low-pass filters, cascaded outputs of the first and second low-pass filters, and output between stages of the first low-pass filter and the second low-pass filter. And a first low-pass filter having a characteristic of passing through a transmission band region of the video signal, and a second low-pass filter passing through a region corresponding to a low-frequency portion in the video signal. And the first and second
The cascade connection of the low-pass filters extracts the component of the region corresponding to the low-frequency portion in the difference signal of the video signal, and extracts the video signal extracted from the stage between the first low-pass filter and the second low-pass filter. By subtracting, from the component of the region corresponding to the transmission band in the difference signal, the component of the region corresponding to the low band portion in the difference signal of the video signal extracted from the cascade connection of the first and second low-pass filters. , A video signal processing device for extracting a component of a region corresponding to a high-frequency portion in a difference signal of a video signal.

A first low-pass filter for extracting a component in a transmission band and a second low-pass filter for extracting a low-frequency component containing no aliasing component are provided. These first and second low-pass filters are cascaded. Connected.
A low-frequency component is extracted from a cascade connection of the first low-pass filter and the second low-pass filter. By subtracting the output of the cascade connection of the first and second low-pass filters from the output between the stages of the first low-pass filter and the second low-pass filter, a high-frequency component is extracted. As a result, the number of taps of the filter can be reduced without deteriorating the characteristics, and the circuit scale can be reduced.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, an input terminal 1 is supplied with a MUSE HDTV signal. The MUSE-type HDTV signal from the input terminal 1 is supplied to one terminal 2A of the switch circuit 2 and, via the delay circuit 4 with a delay amount for two fields,
Is supplied to one terminal 3A. The other terminal 2B of the switch circuit 2 and the other terminal 3B of the switch circuit 3 are grounded.

The terminal 5 is supplied with a sub-sample pulse. This sub-sample pulse is supplied to the switch circuit 2 via the inverter 6 and the switch circuit 3
Supplied to Based on the sub-sample pulse from the terminal 5, the switch circuits 2 and 3
Alternately switched. The switch circuits 2 and 3 output input data when set to the terminals 2A and 3A, respectively, and output "0" data when set to the terminals 2B and 3B.

The outputs of the switch circuits 2 and 3 are supplied to a subtraction circuit 7. The MU of the current field transmitted from the input terminal 1 through the switch circuit 2 by the subtraction circuit 7
The HD signal of the SE system and the MUS two fields before from the input terminal 1 via the delay circuit 4 and the switch circuit 3
The E-system HDTV signal is subtracted. Thus, a difference signal between one frame of the MUSE HDTV signal is obtained from the output of the subtraction circuit 7.

In the MUSE system, image data at different positions are sent in a 4-field cycle, and a difference cannot be obtained as it is. Therefore, the switch circuits 2 and 3 are set so that the difference between one frame is obtained.
As a result, data “0” is inserted. Thus, when data of “0” is inserted between pixels in each field,
The overall gain is 1/2. Therefore, the switch circuit 2
In order to compensate for the decrease in gain due to the insertion of the data “0” between the pixels according to (3) and (3), the gain amplifier 8
Is provided.

The output of the subtraction circuit 7 is supplied to a gain amplifier 8. The gain amplifier 8 provides a double gain. The output of the gain amplifier 8 is supplied to a low-pass filter 9.

The low-pass filter 9 is an MUSE type H
It has the characteristic of passing frequencies within the transmission band of the DTV signal. In the MUSE system, the transmission band is 8.1 MHz
It has been. Therefore, the low-pass filter 9 has a characteristic of passing a frequency of 8.1 MHz or less.
As the low-pass filter 9, a filter having a linear phase characteristic and a symmetric roll-off characteristic is used.

The output of the low-pass filter 9 is supplied to a low-pass filter 10 and to a subtraction circuit 11. The low-pass filter 10 has a characteristic of passing low-frequency components that do not include aliasing components. MU
In the SE method, the aliasing component is not included in the frequency of 4.05 MHz or less. Therefore, the low-pass filter 1
0 is a characteristic that passes a frequency of 4.05 MHz or less.

The output of the low-pass filter 10 is used as the subtractor 1
1 and output from the output terminal 12.
The subtraction circuit 11 is supplied with the component in the transmission band of the MUSE HDTV signal from the low-pass filter 9, and also receives the MUSE HDTV signal from the low-pass filter 10.
A low-frequency component of the signal that does not include a folded component is supplied. In the subtraction circuit 11, a MUSE HDTV
The low-frequency component is subtracted from the component in the transmission band of the signal. Therefore, a high-frequency component in the transmission band of the MUSE HDTV signal is output from the subtraction circuit 11.

The low-pass filter 10 outputs the low-frequency component of the one-frame difference signal of the MUSE HDTV signal. The low-frequency component of the one-frame difference signal is output from the output terminal 12. From the subtraction circuit 11, MUSE
The high frequency component of one frame difference signal of the HDTV signal of the system is output, and the output of the subtraction circuit 11 is output from the output terminal 13.

In the configuration shown in FIG. 1, an input terminal 1 supplies a MUSE HDTV signal. MUS
As shown in FIG. 2A, the spectrum of the E-system HDTV signal has a transmission band of 8.1 MHz, and a high-frequency component higher than a frequency of 4.05 MHz contains a folded component.

In the MUSE system, a sample value is transmitted in an analog manner, and the received signal is resampled on the receiving side. When the transmitted MUSE HDTV signal is resampled, the spectrum becomes as if it were turned around the resampled carrier (frequency 16.2 MHz) as shown in FIG. 2B.

As shown in FIG. 2C, the characteristics of the low-pass filter 9 are such that components within the transmission band pass, that is, characteristics that pass a frequency of 8.1 MHz or less. As shown in FIG. 2D, the low-pass filter 10 has a characteristic of passing a low-frequency component containing no aliasing component, that is, a characteristic of passing a frequency of 4.05 MHz or less.

In FIG. 1, components in the transmission band of the MUSE HDTV signal are extracted by the low-pass filter 9 having the characteristics shown in FIG. 2C. The low-pass filter 10 having the characteristics shown in FIG.
Of the DTV signal, a low-frequency component that does not include a folded component is extracted.

In the subtraction circuit 11, the low-pass filter 9 having the characteristic shown in FIG. 2C and the component in the transmission band of the MUSE HDTV signal extracted by the low-pass filter 9 having the characteristic shown in FIG. Low-pass filter 1
The low-frequency components extracted with the total characteristic of 0 are removed. Therefore, from the subtraction circuit 11, as shown in FIG.
A high-frequency component having a frequency of 4.05 to 8.1 MHz in the transmission band of the MUSE HDTV signal is output.

As described above, in this example, the low-pass filter 9 for extracting all the components of the transmission band and the low-pass filter 10 for extracting the low-frequency component not including the aliasing component are prepared. 10 are cascaded, the low-pass component is extracted from the cascade connection of the low-pass filters 9 and 10, and the output of the cascade connection of the low-pass filters 9 and 10 is subtracted from the output between the stages of the low-pass filters 9 and 10. Thereby, the high frequency component is taken out. In this case, the circuit scale can be reduced.

That is, when extracting a high-frequency component containing a folded component and a low-frequency component not containing a folded component from a difference signal between one frame, conventionally, FIG.
As shown in FIG. 7, a band-pass filter 109 for extracting a high-frequency component including the aliasing component (frequency of 4.05 MHz to 8.1 MHz) and a low-frequency component not including the aliasing component (frequency of less than 4.05 MHz) are extracted. And a low-pass filter 110 for each of them (see FIG. 17). In the configuration shown in FIG. 3, the transfer function of the band-pass filter 109 is H ₁₁ ,
10 transfer function and H _12, an input signal S _IN11, the high frequency side output from the band-pass filter 109 the output S
_OUT11, and the output of the low frequency side output from the low pass filter 110 and S _OUT12, output S _out11 the high frequency _{side, S OUT11 = S IN11 × H} 11 , and the lower frequency output S _OUT12 is, S _OUT12 = S _IN11 × H ₁₂

On the other hand, as shown in FIG. 4, in the configuration using the low-pass filter 9, the low-pass filter 10, and the subtraction circuit 11, the transfer function of the low-pass filter 9 is H
₁ , the transfer function of the low-pass filter 10 is H ₂ , the input signal is S _IN1 , the high-frequency output from the subtraction circuit 11 is S _OUT1 , and the low-frequency output from the low-pass filter 10 is S _OUT2. Then, the output on the high frequency side S _OUT1 is as follows: S _OUT1 = S _IN1 × H ₂ (1−H ₁ ) The output S _OUT2 on the low frequency side is S _OUT2 = S _IN1 × H ₁ × H ₂ .

A configuration using the band-pass filter 109 and the low-pass filter 110 shown in FIG. 3, a low-pass filter 9, a low-pass filter 10, and a subtraction circuit 11 shown in FIG.
In order for the configuration using and to have the same characteristics,
From the above equation, it is sufficient that the relationship of H ₁₁ = H ₂ (1-H ₁ ) H ₁₂ = H ₁ × H ₂ is satisfied.

For example, as shown in FIG. 3, in the case of using the band-pass filter 109 and the low-pass filter 110, the low-pass filter 110 can be constituted by a 17-tap FIR filter as shown in FIG. . FIG.
, The low-pass filter 110 includes a delay circuit 31-
1-31-16, multiplication circuits 32-1 to 32-17,
And an adder circuit 33. The coefficients of this FIR filter are 1/512, 5/512, 12/512, 21/512, 32/512, 43
/ 512, 52/512, 59/512, 62/512, 59/512, 52/512, 43/5
12, 32/512, 21/512, 12/512, 5/512 and 1/512. FIG. 6 shows the characteristics of such a low-pass filter 110. In FIG. 6, the horizontal axis indicates frequency, and the vertical axis indicates gain.

As shown in FIG. 7, the bandpass filter 110 can be constituted by a 17-tap FIR filter. In FIG. 7, the bandpass filter 110 includes a delay circuit 4
1-1 to 41-16 and multiplication circuits 42-1 to 42-17
And an adder circuit 43. The coefficients of this FIR filter are -1/512, -5/512, -12/512, -21/512, -3
2/512, -43/512, -52/512, 69/512, 194/512, 69/5
12, -52/512, -43/512, -32/512, -21/512, -12/51
2, -5/512 and -1/512. FIG. 8 shows the characteristics of such a bandpass filter 110.

On the other hand, a low pass filter 9, a low pass filter 10 and a subtraction circuit 11 as shown in FIG. 4 are used, and a band pass filter 21 and a low pass filter 22 are used as shown in FIG. When the characteristics are the same as the configuration, the configuration of the low-pass filter 9 is as follows.
It has a configuration of a three-tap FIR filter as shown in FIG.

The low-pass filter 9 has a linear phase characteristic known as a distortion-free transmission line and a symmetric roll-off frequency characteristic. This characteristic is a skew symmetry characteristic centered on a half frequency of the sampling frequency.

In FIG. 9, low-pass filter 9 includes delay circuits 51-1 and 51-2 and multiplication circuits 52-1 to 5-5.
2-3 and an adder circuit 53. This FIR
The coefficients of the filter are set to 1/4, 2/4, and 1/4. FIG. 10 shows the characteristics of such a low-pass filter 9.

The configuration of the low-pass filter 10 is a configuration of a 15-tap FIR filter as shown in FIG. 11, low-pass filter 10 includes delay circuits 61-1 to 61-14 and multiplication circuits 62-1 to 6-6.
2-15 and an adding circuit 63. This FI
The coefficients of the R filter are 1/128, 3/128, 5/128, 8/128
, 11/128, 13/128, 15/128, 16/128, 15/128, 13/12
8, 11/128, 8/128, 5/128, 3/128, 1/128. FIG. 12 shows the characteristics of such a low-pass filter 10.

FIG. 13 shows characteristics when the low-pass filter 9 and the low-pass filter 10 are connected in cascade. The low-pass filter 9 and the low-pass filter 10
9 and 11 are used. The characteristics shown in FIG. 13 are similar to the characteristics of low-pass filter 110 shown in FIG.

FIG. 14 shows a cascade connection of the low-pass filter 9 and the low-pass filter 10,
3 shows characteristics when the output between the stages between the low-pass filter 10 and the output of the low-pass filter 10 is subtracted. Low-pass filter 9 and low-pass filter 10
9 and FIG. 11 are used. This figure 1
The characteristic shown in FIG. 4 corresponds to the band-pass filter 21 shown in FIG.
The characteristics are the same.

As described above, with the configuration using the low-pass filter 9, the low-pass filter 10, and the subtraction circuit 11,
The same characteristics as those of the configuration using the band-pass filter 109 and the low-pass filter 110 can be obtained. And
As can be seen by comparing FIGS. 5 and 7 with FIGS. 9 and 11, the low-pass filter 9, the low-pass filter 10,
The configuration using the subtraction circuit 11 can clearly reduce the circuit scale as compared with the configuration using the band-pass filter 109 and the low-pass filter 110.

In the above example, the low-pass filter 9
Is configured with a 3-tap FIR filter, and the low-pass filter 10 is configured with a 15-tap FIR filter.

[0055]

According to the present invention, there are provided a first low-pass filter for extracting a component in a transmission band and a second low-pass filter for extracting a low-frequency component containing no aliasing component. And a second low-pass filter are cascaded. From the cascade connection of the first low-pass filter and the second low-pass filter, a low-frequency component of the one-frame difference signal of the video signal is extracted. By subtracting the output of the cascade connection of the first and second low-pass filters from the output between the stages of the first low-pass filter and the second low-pass filter, the high-frequency component of the one-frame difference signal of the video signal is subtracted. Is taken out. As a result, the number of taps of the filter can be reduced without deteriorating the characteristics, and the circuit scale can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an example of an inter-frame difference detection circuit to which the present invention can be applied.

FIG. 2 is a spectrum diagram used to describe an example of an inter-frame difference detection circuit to which the present invention can be applied;

FIG. 3 is a block diagram used to explain comparison of filter configurations.

FIG. 4 is a block diagram used to explain comparison of filter configurations.

FIG. 5 is a block diagram used for explaining an example of a low-pass filter in FIG. 3;

6 is a frequency characteristic diagram showing characteristics of the low-pass filter in FIG.

FIG. 7 is a block diagram used for describing an example of a bandpass filter in FIG. 3;

FIG. 8 is a frequency characteristic diagram showing characteristics of the bandpass filter in FIG. 3;

FIG. 9 is a block diagram used to describe an example of a first low-pass filter in FIG.

10 is a frequency characteristic diagram illustrating characteristics of a first low-pass filter in FIG.

FIG. 11 is a block diagram used to describe an example of a second low-pass filter in FIG.

12 is a frequency characteristic diagram showing characteristics of a second low-pass filter in FIG.

FIG. 13 is a frequency characteristic diagram showing an overall characteristic of a cascade connection of two low-pass filters.

FIG. 14 is a frequency characteristic diagram showing an overall characteristic by two low-pass filters and a subtraction circuit.

FIG. 15 is a schematic diagram used for describing the MUSE system.

FIG. 16 is a spectrum diagram used for describing the MUSE system.

FIG. 17 is a block diagram of an example of a conventional inter-frame difference detection circuit.

FIG. 18 is a spectrum diagram used for describing an example of a conventional inter-frame difference detection circuit.

[Explanation of symbols]

4 ... delay circuit, 7, 11 ... subtraction circuit, 9, 10
... Low-pass filters

Claims (3)

[Claims] 1. An HDTV that is subsampled and transmitted
A video signal processing device configured to extract a difference signal between frames of the video signal into a low-frequency part and a high-frequency part, respectively, wherein the first and second low-pass filters are cascaded; A subtraction means for subtracting an output of the cascade connection of the first and second low-pass filters and an output between the stages of the first low-pass filter and the second low-pass filter, wherein the first low-pass filter is The second low-pass filter has a characteristic of passing through a region corresponding to a low-frequency portion in the video signal; and the cascade of the first and second low-pass filters. By the connection, a component of a region corresponding to the low-frequency portion in the difference signal of the video signal is extracted, and a stage of the first low-pass filter and the second low-pass filter From a component of the region corresponding to the transmission band in the difference signal of the extracted said video signal from said first and second
By subtracting the component of the region corresponding to the low-frequency portion in the difference signal of the video signal extracted from the cascade connection of the low-pass filter, the region corresponding to the high-frequency portion in the difference signal of the video signal A video signal processing device for extracting a component of 2. The video signal processing apparatus according to claim 1, wherein said first low-pass filter has a roll-off characteristic. 3. The video signal processing apparatus according to claim 1, wherein the low-frequency band is a band including no aliasing component.