JPH10308930A - Motion detector and its method for multiplex sub-sampling coded signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent double image disturbance without causing deterioration in a motion detection characteristic even on the occurrence of a quasi-still code. SOLUTION: A one-frame motion detection section 1 obtains a motion detection signal based on a 1-frame difference signal of a low frequency component of a video signal and an inter-2-frame motion detection section 2 obtains a motion detection signal based on a inter 2 frame difference signal of the low frequency component of the video signal. In the case that a quasi-still code from a terminal 8 indicates a quasi-still state, a changeover switch 7 is thrown to the position of an attenuator 6 so as to decrease a level of the 1-frame motion detection signal of the low frequency component and the resulting signal is fed to a mixer circuit 3, where the signal is mixed with a signal from the inter-2-frame motion detection section 2 and from which a motion detection signal is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for detecting a motion in a decoder for receiving a broadcast signal to be transmitted by encoding a video signal as a high-definition image by a multi-subsampling encoding system.

[0002]

2. Description of the Related Art Various high-definition television signal standards for transmitting video information of higher image quality with respect to a standard NTSC television signal or the like are known. The luminance signal band of the video signal is 22 MHz, and the color difference signal band is 7 MHz. In such high-definition broadcasting, it is necessary to compress the baseband signal band to about 8 MHz in order to transmit it on one channel of satellite broadcasting (27 MHz). As a compression technique, so-called MUSE (Multiple Sub-nyquid) is used.
st Sampling Encoding: Multiple subsampling encoding)
The system has been adopted and put to practical use.

In the MUSE system, a high-definition television signal is sub-sampled in a pattern that makes a round in four fields, and a screen of one frame is interpolated from a screen of four fields in a still image part, and a moving image is formed. In the part, the screen of one frame is interpolated by the pixels in one field.

FIG. 6 is a block circuit diagram showing an example of a conventional motion detecting device used in the above-mentioned MUSE type decoder.

In FIG. 6, a multiplexed sub-sampling coded signal (so-called MU) supplied to an input terminal 101 is shown.
The SE signal is sent to the noise reducer 102.
The noise reducer 102 includes an adder circuit 111 and a coring circuit 112.
12, a difference signal between two frames from the adding circuit 121 is input. The input signal and the difference signal between two frames from the coring circuit 112 are added by the adding circuit 111,
Noise is removed.

The output S1 from the noise reducer 102
01 is supplied to the frame memory 115, and the input signal is delayed by one frame by the frame memory 115. The output S102 from the frame memory 115 is supplied to the subtraction circuit 117. An output S101 from the noise reducer 102 is supplied to a subtraction circuit 117 via an interpolation filter 118. The interpolation filter 118
An interpolated pixel is formed such that a so-called MUSE signal of a sampling pattern that makes a round in a field can obtain an inter-frame difference signal.

The subtraction circuit 117 uses the frame memory 1
15 and the output S101 of the noise reducer 102 via the interpolation filter 118 are subtracted to obtain a one-frame difference signal. Subtraction circuit 11
7 is supplied to a bit length compression circuit 119. The bit length compression circuit 119 compresses the bit length by using, for example, non-linear characteristics. The output of the bit length compression circuit 119 is delayed by one frame via the frame memory 120 and supplied to the addition circuit 121.

The output S10 of the frame memory 115
2 is supplied to the subtraction circuit 123 via the interpolation filter 122. Output S101 of noise reducer 102
Is supplied to the subtraction circuit 123. Interpolation filter 122
Is to form an interpolated pixel so that a one-frame difference is obtained by a so-called MUSE signal of a sampling pattern that makes one cycle in four fields. The frame memory 1 passed through the interpolation filter 122 by the subtraction circuit 123
The output S102 of the 15 and the output S101 of the noise reducer 102 are subtracted to obtain an inter-frame difference signal.

The output of the subtraction circuit 123 is supplied to a bit length compression circuit 125. The bit length compression circuit 125 compresses the bit length by using, for example, non-linear characteristics. The output of the bit length compression circuit 125 is sent to the addition circuit 121.

The output S101 of the noise reducer 102
From the current field 0V, and the field (−2) immediately before the output S102 of the frame memory 115.
V), the subtraction circuit 11
7, (0V signal) − (− 2V signal) is obtained, and this is delayed by one frame by the frame memory 120. Therefore, the output of the frame memory 120 is (2V signal) − (− 4V signal). ).

Since the subtraction circuit 123 subtracts the current field 0V and the immediately preceding field (-2V), the output of the bit length compression circuit 125 is (0V signal)-(-2V signal). Becomes

Therefore, in the addition circuit 121, the above (0V
Signal) − (− 2V signal) and the above (−2V signal)
− (− 4V signal) is added to obtain (0V signal) − (− 4V signal), and a difference signal between two frames is obtained.

The difference signal between the two frames obtained as described above is passed through the prohibition control circuit 131 to the motion detecting section 1.
03 and to the coring circuit 112 of the noise reduction unit 102.

The output S10 of the frame memory 115
2 is supplied to a subtraction circuit 127 via an interpolation and low-pass filter 126. The output S101 from the noise reducer 102 is supplied to the subtractor 127 via the low-pass filter 128. The interpolation and low-pass filter 126 forms an interpolated pixel so that a one-frame difference is obtained by a so-called MUSE signal of a sampling pattern that makes a round in four fields, and extracts a component having a frequency of, for example, 4 MHz or less so that aliasing does not occur. It is. The low-pass filter 128 extracts, for example, a component having a frequency of 4 MHz or less so that aliasing does not occur. Output S102 of frame memory 115 from which low-frequency components have been extracted by subtraction circuit 127
Is subtracted from the input signal S101 from which the low-frequency component has been extracted, and a difference signal of the low-frequency component for one frame is obtained.

An input signal S to the frame memory 115
Assuming that 101 and the output signal S102 are signals of the current field 0V and the field of the previous field (-2V), the subtraction circuit 127 obtains (0V signal)-(-2V signal). become.

The inter-frame difference signal of the low-frequency component obtained in this manner is supplied to the motion detecting section 103 and also to one input terminal of the comparator 132. The other input terminal of the comparator 132 is given a threshold level th. Comparator 132
Is supplied to the prohibition control circuit 131 via the frame memory 134.

The prohibition control circuit 131 includes a frame memory 1
Based on the output of the comparator 132 via
Perform prohibition control. The comparator 132 determines whether or not the level of the low-frequency one-frame difference signal is equal to or higher than the threshold level th. When the level of the low-frequency one-frame difference signal is equal to or lower than the threshold level th, the two-frame difference signal obtained by the addition circuit 121 is supplied to the motion detection unit 103. When the level of the low-frequency one-frame difference signal is equal to or higher than the threshold level th, 2
The supply of the inter-frame difference signal to the motion detection unit 103 is prohibited, and the motion is detected by the one-frame difference signal from the subtraction circuit 127.

The motion detecting circuit 103 includes an adder 121
The motion detection is performed using the two-frame difference signal from the subtractor 127 and the low-frequency component one-frame difference signal from the subtraction circuit 127. The output of the motion detection circuit unit 103 is output from the output terminal 105.

The still image processing unit 104 performs a still image interpolation process for interpolating a screen of one frame from a screen of four fields. The still image processing unit 104 includes an inter-frame interpolation circuit 141 and an inter-field interpolation processing circuit 142.
And a field memory 143. The output S101 of the noise reducer 102 and the output S102 of the frame memory 115 are connected to the frame interpolation circuit 141.
Supplied to The output of the frame interpolating circuit 141 is supplied to the field interpolating circuit 142 and, via the frame memory 143, the field interpolating circuit 142.
Supplied to The output of the inter-field interpolation circuit 142 is output from the output terminal 144.

As described above, in the conventional motion detection circuit,
The difference signal between two frames is obtained in the whole band, and the difference signal between one frame is obtained by cutting the high frequency band. If the difference signal between one frame is equal to or higher than the threshold level, the input of the difference signal between two frames is prohibited, and the difference signal between two frames is prohibited. By using the difference signal, it is possible to cope with a fast movement and to prevent aliasing.

That is, for example, Japanese Patent Application Laid-Open No. 62-17287
As disclosed in Japanese Patent Application Laid-Open No. 6-264, it is preferable to use an inter-frame difference signal in order to follow a fast motion, but aliasing distortion may occur in the inter-frame difference signal. Therefore, after cutting the high-frequency component with the low-pass filter 128 and the interpolation and low-pass filter 126,
The difference signal between one frame is obtained by the subtraction circuit 127. If the difference signal between one frame is sufficiently large, the input of the difference signal between two frames is prohibited by the prohibition control circuit 131, and the difference signal between one frame is used. Performs motion detection.

Next, FIG. 7 shows that when a quasi-stationary code is generated, 1
1 shows a schematic configuration of a motion detection device that forcibly prohibits motion detection between frames. Here, the quasi-stationary code is a code specified in the case of a video that has a slight movement but can be regarded as almost still, for example, a so-called MUS
In the case of the E system, it is one of eight levels of motion specified by 3 bits as motion information in a control signal added for each field.

In FIG. 7, an inter-frame motion detecting section 1
In 51, only the input signal of the low-frequency component (for example, 4 MHz or less) performs motion detection based on the difference between one frame, and the two-frame motion detection unit 152 performs motion detection based on the difference between two frames of the input signal in the entire band. The signals from the motion detectors 151 and 152 are detected by the mixing circuit 15.
3 (corresponding to the motion detection circuit unit 103 in FIG. 6)
A signal from the inter-frame motion detection unit 151 is A
A prohibition control circuit 157 using an ND gate or the like is used. As shown in the example of FIG. 6, the one-frame motion detecting unit 151 first performs the low-pass filter (126 or 12).
8), the difference may be obtained after extracting the low-frequency component. However, as shown in FIG. 8, the signal of the current frame of the terminal 161 and the signal of the previous frame of the terminal 162 are subtracted by the subtraction circuit 163. Later, LPF (Low Pass Filter) 1
For example, a low-frequency component of 4 MHz or less may be extracted from the signal 64 and sent to the terminal 165 as a motion detection signal for one frame.

The prohibition control by the AND gate of the prohibition control circuit 157 is performed by a quasi-stationary code from a terminal 158. When the quasi-stationary code is designated, the AND gate of the prohibition control circuit 157 is controlled to be in the cut-off state,
The signal from the inter-frame motion detection unit 151 is
Prohibit sending to 3.

That is, when a quasi-stationary code is generated, the motion detection signal for one frame, which is likely to cause erroneous detection of a still image as a moving image, is forcibly prohibited because of aliasing interference. This is performed only with the motion detection signal. This is because the spectrum of a so-called MUSE signal of a still image is as shown in FIG. 9, and the low-pass filter characteristic (the characteristic of the LPF 164 in FIG. 8) in the one-frame motion detector 151 is as shown in FIG. This is because aliasing interference occurs in the spectrum portion A in FIG. 9 and the low-pass filter characteristic portion B in FIG. Since a still image takes the same sample point in a two-frame sequence, the motion detection signal between two frames has no aliasing interference.

[0026]

By the way, if the motion detection signal for one frame is forcibly prohibited in the quasi-stationary mode, when a signal having a frequency component of 4 MHz or more moves (however, the amount is Small), detection omission may occur, and double image interference may occur in a reproduced image.
In particular, in order to reduce memory, the applicant of the present application has previously filed Japanese Patent Application
As proposed in the specification and drawings of Japanese Patent No. 188570, motion detection is performed by dividing the motion into bands and detecting only an input signal of 4 MHz or less, and between two frames detecting only an input signal of 4 MHz or more. When the combination with the motion detection is used, there is a case where a low-frequency motion detection leak occurs at the time of quasi-stationary and a double image is formed.

The present invention has been made in view of such circumstances, and a multiplexing method capable of preventing adverse effects such as double image interference without deteriorating motion detection characteristics even when a quasi-stationary code is generated. It is an object of the present invention to provide an apparatus and a method for detecting motion of a sub-sampling coded signal.

[0028]

According to the present invention, in order to solve the above-mentioned problem, when performing motion detection by combining motion detection between one frame and motion between two frames, the input multiple subsampling is performed. When the coded signal is in the quasi-stationary state, at least one of the one-frame motion detection signal and the two-frame motion detection signal is attenuated and used.

Preferably, at the time of motion detection, only a low-frequency component is detected by a difference between one frame, and only a high-frequency component is detected by a difference between two frames. To reduce the motion detection signal.

In the quasi-stationary state, the motion detection signal is not forcibly inhibited but is only attenuated.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus and a method for detecting a motion of a multi-subsampling coded signal according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a motion detecting portion of a decoder for decoding a multiplexed sub-sampling coded signal, for example, a so-called MUSE signal.

In FIG. 1, the inter-frame motion detecting section 1 uses a difference between one frame of a low-frequency component of a multiplexed sub-sampling coded signal, for example, a video signal of a so-called MUSE signal, for example, a component of 4 MHz or less. Then, a motion detection signal is taken out for one frame in a low frequency range, and sent to the attenuator 6 and the changeover switch 7, respectively. The attenuator 6 and the changeover switch 7 constitute an attenuation control circuit. The attenuator 6 attenuates the input motion detection signal for one frame to reduce the output level. send. Changeover switch 7
Switches and selects the signal from the inter-frame motion detector 1 and the signal from the attenuator 6 according to the quasi-stationary code from the terminal 8 and sends the signal to the mixing circuit 3.

The inter-frame motion detector 2 shown in FIG. 1 performs motion detection based on a difference between two frames of a high frequency component of the video signal of the multiplexed sub-sampling coded signal, for example, a component of 4 MHz or more. The obtained high-frequency two-frame motion detection signal is sent to the mixing circuit 3.

Here, the quasi-stationary code supplied to the terminal 8 is a code indicating a state of an image which has slight movement but can be regarded as almost stationary. For example, in the case of the so-called MUSE method, this quasi-stationary code is defined as one of eight levels of motion as motion information represented by three bits in a control signal added for each field. I have.

When the quasi-stationary code is detected on the decoder side, the changeover switch 7 of the above-mentioned attenuation control circuit is connected to the attenuator 6 side by switching, so that the one-frame motion detector 1
The motion detection signal is not forcibly inhibited, and is sent to the mixing circuit 3 at a low output level in consideration of the fact that the quasi-stationary state is almost stationary. The amount of attenuation in the attenuator 6 may be determined so that a double image due to detection omission is inconspicuous, for example, 、 ３ times or 1 / times.
The value may be set appropriately in consideration of the actual circuit configuration. When it is not in the quasi-stationary state, the changeover switch 7 of the attenuation control circuit is connected to the motion detecting section 1 for one frame.

In this manner, false detection of a still image as a moving image slightly increases due to aliasing, but double image interference that is conspicuous can be reduced.

The configuration of the inter-frame motion detection section 1 is as follows. As shown in FIG. 8, the inter-frame difference is obtained, and then a low-pass component (for example, a component of 4 MHz or less) is applied by an LPF (low-pass filter). You may take it out,
Alternatively, as shown in FIG.
After the low-frequency components of the two signals are extracted first by the LPFs 126 and 128, the difference between them is subtracted by a subtractor 127.
It may be taken out with. The same applies to the motion detection unit 2 between two frames.

Next, in order to explain the operation of the motion detecting device having the structure shown in FIG. 1, a motion detecting device having a structure as shown in FIG. 2 will be considered.

The motion detection apparatus shown in FIG. 2 includes an inter-frame motion detection section 171 for performing motion detection based on an inter-frame difference signal of a low-frequency component (for example, a component of 4 MHz or less), and a high-frequency component (for example, 4 MHz or more). 2) motion detection unit 1 that performs motion detection based on the two-frame difference signal
72, the signal from the one-frame motion detection section 171 is sent to the mixing circuit 173 via the inhibition control circuit 177 using an AND gate, and the signal from the two-frame motion detection circuit 172 is directly used as the mixing circuit. 173. When the quasi-stationary state is indicated by the quasi-stationary code from the terminal 178, the prohibition control circuit 177 forcibly prohibits the signal from the one-frame motion detector 171 and
I try not to send it to 3.

In the motion detecting device shown in FIG. 2, compared with the motion detecting device shown in FIG. 7, the inter-frame motion detecting section 171 only needs to obtain the difference between two frames including only the high-frequency component, thereby reducing the memory capacity. Can be performed. However, if the one-frame motion detection signal is forcibly prohibited when the quasi-stationary code is generated, detection omission may occur and a double image may be formed.

Here, FIG. 7, FIG. 2 and FIG.
Table 1, Table 2, and Table 3 show the state of the motion detection operation of each of the motion detection devices shown in FIG. That is, Table 1 below shows the motion detecting operation shown in FIG. 7, Table 2 shows the motion detecting device shown in FIG. 2, and Table 3 shows the motion detecting operation shown in FIG. 1. Is shown.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

In Tables 1 to 3, ○ indicates that detection is detected, and X indicates that detection is not performed. (A) indicates the above-mentioned forced prohibition, and (b) indicates that detection is omitted. c)
Indicates that the detection is performed with the level reduced.

That is, the band of the motion detection is divided to reduce memory, etc., and the motion detection for one frame of a low-frequency (for example, 4 MHz or less) signal and a high-frequency (for example, 4 MHz or less) signal are performed.
In the case where the inter-frame motion detection signal for the low frequency band is completely prohibited when the quasi-stationary code is generated as shown in FIG. As indicated by “× (b)” on the low frequency side, detection omission may occur, resulting in a double image.

Therefore, in the embodiment of the present invention shown in FIG. 1, the attenuation control circuit composed of the attenuator 6 and the changeover switch 7 takes into account that there is almost no movement in the quasi-stationary state, and takes into account the low frequency range. In this case, the level of the motion detection signal during one frame is reduced and sent to the mixing circuit 3, thereby eliminating omission of detection and preventing double image interference.

Next, an example in which the above-described embodiment of the present invention is applied to the motion detecting apparatus for a sub-sampling signal disclosed in the specification and the drawings of Japanese Patent Application No. 8-188570 by the present applicant will be described. This will be described with reference to FIG.

FIG. 3 is a block circuit diagram showing an example of a conventional motion detecting device used for a so-called MUSE type decoder. A multiplexed sub-sampling coded signal (so-called MUSE signal) is supplied to an input terminal 10. You. The so-called MUSE signal from the input terminal 10 is
The signal is sent to the noise reducer 60.

The noise reducer 60 includes an adder 1
1 and 12 and coring circuits 13 and 14. The coring circuit 13 receives the one-frame difference signal of the low-frequency component from the subtraction circuit 27. The adder circuit 11 adds the input signal and the correlated low-frequency component inter-frame difference signal to remove low-frequency noise.
The coring circuit 14 receives the difference signal between the two frames of the high frequency component from the adding circuit 21. The adder circuit 12 adds the input signal and the correlated high-frequency component difference signal between two frames, and removes high-frequency noise.

The output S1 from the noise reducer 60
Is supplied to the frame memory 15, which delays the input signal by one frame. The output S2 from the frame memory 15 is supplied to a subtraction circuit 17. The high-pass filter 16 has a characteristic of extracting a component having a frequency of, for example, 4 MHz or more in the input signal. The interpolation and high-pass filter 18 forms an interpolation pixel and extracts a component having a frequency of 4 MHz or more, for example, so that a so-called MUSE signal having a sampling pattern that makes one cycle in four fields can obtain an inter-frame difference signal.

The subtraction circuit 17 subtracts the output S2 of the frame memory 15 from which the high-frequency component has been extracted and the output S1 of the noise reducer 60 from which the high-frequency component has been extracted, to obtain a one-frame difference signal. . Subtraction circuit 17
Is supplied to the bit length compression circuit 19. The bit length compression circuit 19 compresses the bit length by using, for example, non-linear characteristics. The output of the bit length compression circuit 19 is delayed by one frame via the frame memory 20 and supplied to the addition circuit 21.

The output S2 of the frame memory 15 is
Subtraction circuit 23 via interpolation and high-pass filter 22
Supplied to The output S1 of the noise reducer 60 is
It is supplied to the subtraction circuit 23. The interpolation and high-pass filter 22 forms an interpolated pixel so that a one-frame difference is obtained from a so-called MUSE signal of a sampling pattern that makes one cycle in four fields.
It is to extract the component above MHz. Subtraction circuit 23
As a result, the output S2 of the frame memory 15 from which the high frequency component has been extracted and the output S1 of the noise reducer 60 from which the high frequency component has been extracted are subtracted, and a difference signal of the high frequency component between one frame is obtained.

The output of the subtraction circuit 23 is supplied to a bit length compression circuit 25. The bit length compression circuit 25 compresses the bit length by using, for example, non-linear characteristics.
Sent to 1.

From the output S 1 of the noise reducer 60, the signal of the current field 0 V is read from the frame memory 15.
Assuming that the signal of the field (−2V) two fields before is obtained from the output S2 of (1), (0V signal) − (− 2V signal) is obtained by the subtraction circuit 17, and this is obtained by the frame memory 20. Since the output is delayed by one frame, the output of the frame memory 20 is (-2V signal)-(-4V signal).

Also, the subtraction circuit 23 subtracts the signal of the current field 0V and the signal of the immediately preceding field (-2V), so that the output of the bit length compression circuit 25 becomes (0V signal)- (-2V signal).

Therefore, in the adder circuit 21, the (0V signal)-(-2V signal) and the (-2V signal)-
(0 V signal) − (− 4 V signal) are obtained, and the addition circuit 21 obtains a high-frequency component difference signal between two frames.

The difference signal between the two frames obtained in this way is supplied to the motion detection circuit unit 30 and also to the coring circuit 14 of the noise reduction unit 60.

The output S2 of the frame memory 15 is
The signal is supplied to a subtraction circuit 27 via an interpolation and low-pass filter 26. Output S1 from noise reducer 60
Is supplied to the subtraction circuit 27 via the low-pass filter 28. The interpolation and low-pass filter 26 is a so-called MUSE of a sampling pattern that makes one cycle in four fields.
Interpolated pixels are formed so that a one-frame difference is obtained from a signal, and a component having a frequency of, for example, 4 MHz or less is extracted so that aliasing does not occur. The low-pass filter 28 extracts, for example, a component having a frequency of 4 MHz or less so that aliasing does not occur. The subtraction circuit 27 subtracts the output S2 of the frame memory 15 from which the low-frequency component has been extracted and the input signal S1 from which the low-frequency component has been extracted, and obtains a difference signal of the low-frequency component in one frame.

Input signal S1 to frame memory 15
And the output signal S2 are the current fields 0V, 2V, respectively.
Assuming that the signal is in the immediately preceding field (−2 V), the subtraction circuit 27 obtains (0 V signal) − (− 2 V signal).

The low-frequency component inter-frame difference signal obtained in this manner is supplied to the motion detecting circuit 30 via the attenuation control circuit including the attenuator 36 and the changeover switch 37, and the noise reduction is performed. The signal is supplied to the coring circuit 13 of the unit 60.

The damping control circuit corresponds to the damping control circuit shown in FIG. 1 (comprising the attenuator 6 and the changeover switch 7), and the changeover switch 37 is switched according to the quasi-stationary code supplied to the terminal 38. The switching control is performed, and the one-frame difference signal of the low-frequency component from the subtraction circuit 27 is taken out as it is or after being attenuated by the attenuator 36 and sent to the motion detection circuit unit 30. That is, in the quasi-stationary state, the changeover switch 37 is switched and connected to the attenuator 36 side,
The output level of the one-frame difference signal of the low-frequency component from the subtraction circuit 27 is reduced and sent to the motion detection circuit unit 30.

The motion detection circuit unit 30 calculates the difference between the two-frame high-frequency component signal from the adder 21 and the one-frame low-frequency difference signal obtained from the subtraction circuit 27 via the attenuation control circuit. Is used to perform motion detection. The output of the motion detection circuit unit 30 is output from the output terminal 50.

The still image processing section 40 performs a still image interpolation process for interpolating a screen of one frame from a screen of four fields. The still image processing unit 40 includes a frame interpolation circuit 41, a field interpolation processing circuit 42, and a field memory 43. The output S1 of the noise reducer 60 and the output S2 of the frame memory 15 are supplied to an inter-frame interpolation circuit 41. The output of the frame interpolation circuit 41 is supplied to the field interpolation circuit 42 via the frame memory 43 while being supplied to the field interpolation circuit 42. The output of the inter-field interpolation circuit 42 is output from the output terminal 44.

As described above, in this example, a high-frequency component is extracted to obtain a two-frame differential signal, and a low-frequency component is extracted to obtain a one-frame differential signal. Motion detection is performed using a signal and a low-frequency component inter-frame difference signal. Since only the high-frequency component is extracted and the difference signal between two frames is detected, compared to the case where the difference between two frames is detected over the entire band, there is no redundancy, and the capacity of the frame memory 20 is reduced accordingly. I can do it. Also, if only the high-frequency component is extracted and the difference signal between two frames is detected, the dynamic range is not widened, so that the bit precision in the bit length compression circuits 19 and 25 can be improved.

That is, in order to follow a fast movement, it is preferable to use a difference signal between one frame.
In the one-frame difference signal, aliasing may occur. Therefore, after the high-frequency component is cut by the low-pass filter 28 and the interpolation and low-pass filter 26, the subtraction circuit 27 obtains the difference signal between one frame. Since the one-frame difference signal is obtained by cutting high-frequency components, motion can be detected on a screen including many low frequencies, but motion cannot be detected on a screen including many high frequencies. Therefore, a high-frequency component is extracted and a difference signal between two frames is detected. As a result, on a screen including many low frequencies, only low frequencies are extracted and motion is detected by the inter-frame difference signal, so that it is possible to cope with fast motion. In a screen including many high frequencies, since only the high frequencies are extracted and motion is detected by a difference signal between two frames, aliasing does not occur.

When the quasi-stationary code is detected on the decoder side, the changeover switch 37 of the attenuation control circuit is connected to the attenuator 36 to force the motion detection signal from the motion detector 1 for one frame. In consideration of the fact that quasi-stationary is almost stationary, the output level is reduced and sent to the motion detection circuit unit 30 without being prohibited, so that double images can be made inconspicuous. And the motion detection characteristics can be improved.

Next, FIG. 4 shows a second embodiment of the present invention, in which an attenuation control circuit is also provided on the output side of the high frequency inter-frame motion detecting section 2. That is, the output signal from the low-frequency one-frame motion detecting unit 1 is output to the attenuator 6.
a to the mixing circuit 3 via an attenuation control circuit consisting of a changeover switch 7a and a changeover switch 7a.
Is sent to the mixing circuit 3 via an attenuation control circuit comprising an attenuator 6b and a changeover switch 7b. Each changeover switch 7a, 7b of these attenuation control circuits
Are switched to the attenuators 6a and 6b, respectively, when the quasi-stationary code from the terminal 8 is present. Therefore, during quasi-stationary, the level of each motion detection signal is reduced and sent to the mixing circuit 3.

Here, instead of using the attenuation control circuit on the output side of the inter-frame motion detector 1 in FIG. 4, an attenuation control circuit may be provided only on the output side of the inter-frame motion detector 2. Good.

Also in the case of the second embodiment, it is possible to eliminate the omission of detection at the time of quasi-stationary while performing band-separated motion detection for saving memory, to prevent double image disturbance, and to obtain a motion detection characteristic. Can be improved.

The present invention is not limited to the above-described embodiment. For example, as shown in FIG. 5, motion detection between two frames may be performed in all bands. The configuration of the third embodiment shown in FIG. 5 corresponds to a configuration in which the high-frequency two-frame motion detection unit 2 of the configuration of FIG. 1 is replaced with a full-band two-frame motion detection unit 4. For the other parts, corresponding parts are denoted by the same reference symbols, and description thereof is omitted. Also, when the motion detection unit 4 between two frames performs motion detection in all bands as in the configuration of FIG. 5, the above-described attenuation control circuit may be provided on the output side of the motion detection unit 4. In addition, it goes without saying that various changes can be made without departing from the spirit of the present invention.

[0073]

According to the present invention, when the first motion detection signal obtained based on the inter-frame difference signal of the low frequency component of the video signal is in the quasi-stationary state, the attenuation control is performed, and the high level of the video signal is obtained. Since the motion detection signal is mixed with the second motion detection signal based on the difference signal between the two frames of the band component, the motion detection signal is only attenuated in the quasi-stationary state without forcibly prohibiting the motion detection signal. Double image disturbance can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a main part of an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a motion detection device as a comparative example used for describing the present invention.

FIG. 3 is a block diagram illustrating a specific example of a motion detection device to which an embodiment of the present invention has been applied.

FIG. 4 is a block diagram showing a schematic configuration of a main part according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a schematic configuration of a main part according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a conventional example of a motion estimation device for a decoder for a multiplexed sub-sampling coded signal.

FIG. 7 is a block diagram showing another conventional example of a motion detection device.

FIG. 8 is a block diagram illustrating an example of an inter-frame motion detection unit.

FIG. 9 is a graph showing a state of folding of a multiplexed sub-sampling coded signal subjected to still image processing.

FIG. 10 is a graph showing an example of characteristics of a low-pass filter used for one-frame motion detection.

[Explanation of symbols]

1,171 Low-frequency inter-frame motion detection unit, 2,1
72 High frequency inter-frame motion detector, 3,173
A mixing circuit, 4 a motion detector for two frames in all bands,
6, 6a, 6b attenuator, 7, 7a, 7b switch

Claims (8)

[Claims] An apparatus for detecting a motion of a multiplexed sub-sampling coded signal for detecting a motion when decoding a video signal coded by a multiplexed sub-sampling coding method, comprising: A first motion detection unit for obtaining a motion detection signal based on the difference signal; a second motion detection unit for obtaining a motion detection signal based on a two-frame difference signal of a high-frequency component of the video signal; Attenuating control means for attenuating and outputting the one-frame motion detection signal from the first motion detecting means when in a stationary state; one-frame motion detecting signal from the attenuating control means; and the second motion detecting means Means for outputting a motion detection signal by mixing the motion detection signal between two frames with the motion detection signal between two frames. 2. The apparatus according to claim 1, further comprising: an attenuation control unit that attenuates and outputs a motion detection signal between two frames from the second motion detection unit when the video signal is in a quasi-stationary state. For detecting motion of a multiplexed sub-sampling coded signal. 3. The attenuating control means includes: attenuating means for attenuating an input signal; and the input signal and an output signal from the attenuating means according to a quasi-stationary code included in a control signal of the multiplexed sub-sampling coded signal. 2. A motion detecting apparatus for a multiplexed sub-sampling coded signal according to claim 1, further comprising a switching means for switching and selecting one of the signals and outputting the selected signal. 4. A motion detection method for a multiplexed sub-sampling coded signal for detecting a motion when decoding a video signal coded according to a multiplexed sub-sampling coding method, comprising the steps of: A first motion detection step of obtaining a motion detection signal based on the difference signal; a second motion detection step of obtaining a motion detection signal based on a two-frame difference signal of a high-frequency component of the video signal; Attenuating and outputting the inter-frame motion detection signal in a stationary state; and mixing the obtained inter-frame motion detection signal with the inter-frame motion detection signal to output a motion detection signal. A motion detection method for a multiplexed sub-sampling coded signal. 5. A motion detecting apparatus for a multiplexed sub-sampling coded signal for detecting a motion when decoding a video signal coded according to a multiplexed sub-sampling coding method, comprising the steps of: First motion detection means for obtaining a motion detection signal; second motion detection means for obtaining a motion detection signal based on a difference signal between two frames of the video signal; and the first motion detection means when the video signal is in a quasi-stationary state. Attenuation control means for attenuating and outputting a one-frame motion detection signal from the motion detection means; one-frame motion detection signal from the attenuation control means; and two-frame motion detection signal from the second motion detection means. And a means for outputting a motion detection signal by mixing the motion detection signal with the sub-sampled coded signal. 6. An attenuating control means for attenuating and outputting a motion detection signal between two frames from the second motion detecting means when the video signal is in a quasi-stationary state. For detecting motion of a multiplexed sub-sampling coded signal. 7. The attenuating control means includes an attenuating means for attenuating an input signal, and the input signal and an output signal from the attenuating means according to a quasi-stationary code included in a control signal of the multiplexed sub-sampling coded signal. 6. A motion detecting apparatus for a multiplexed sub-sampling coded signal according to claim 5, further comprising switching means for switching and selecting any one of the signals and outputting the selected signal. 8. A motion detection method for a multiplexed sub-sampling coded signal for detecting a motion when decoding a video signal coded according to a multiplexed sub-sampling coding method, comprising the steps of: A first motion detection step for obtaining a motion detection signal; a second motion detection step for obtaining a motion detection signal based on a difference signal between two frames of the video signal; Multiplexing, comprising: attenuating and outputting a motion detection signal; and mixing the obtained one-frame motion detection signal and the two-frame motion detection signal to output a motion detection signal. A motion detection method for a sub-sampling coded signal.