JPH1093976A - Motion detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motion detector which can extract and modify a motion vector detection error. SOLUTION: A motion detector is provided with a motion detection block 14 which detects a motion vector between a previous odd field and a present odd field, a motion vector between the present odd field and the following odd field, a motion vector between a previous even field and a present even field and a motion vector between the present even field and the following even field, and an evaluation block 15 which seeks the difference of each vector, finds out the motion vector that makes a detection error when the value is bigger than a prescribed threshold, and also modifies the motion vector that makes the detection error into a correct value. Therefore, it can reduce detection errors of a motion vector and acquire a satisfactory reproduced image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion detecting apparatus suitable for use in, for example, a moving picture coding and transmitting apparatus for digital image communication and digital television broadcasting, and a digital television receiver.

[0002]

2. Description of the Related Art Conventionally, in a moving picture coding and transmitting apparatus for digital television broadcasting and a high-definition television receiver for reproducing after transmitting image data, it is conceivable to transmit raw data as it is. Since the data capacity is large, storing or transmitting raw data as it is requires a large-capacity memory, which is not efficient.

Therefore, in these apparatuses, image data is compressed with high efficiency. That is,
In a moving image encoding and transmitting apparatus, image data is compressed and transmitted, and then expanded and reproduced in a high-definition television receiver.

[0004] A motion compensation process before compressing image data in an encoding device such as a moving image encoding transmission device, and a post-compression process after decompressing compressed image data in a decoding device such as a high-definition television receiver. In a filter process, a motion vector of a moving image is obtained, and the encoding device performs encoding using the motion-corrected difference signal, and the decoding device performs decoding.

[0005] Motion detection has been performed using a pixel in a frame one frame before a moving image or in a frame before that as a reference pixel. In order to increase the detection accuracy and the detection efficiency of the motion, it is important how to detect the motion in the moving image. Hereinafter, a block matching method used in the conventional motion detection will be described.

[0006] The block matching method used in a conventionally used motion detection device has been performed using an image of a current frame and an image of a previous frame. In other words, this block matching method obtains the position of the block where the sum of the difference between the pixel value of a certain block on one image and the pixel value of the block at a certain position on the other image is the smallest, and that position is determined. Is detected as a motion vector.

[0007]

However, in the above-described conventional motion detection method, one type of motion vector between the preceding and succeeding frames is obtained, and encoding and decoding are performed using this one type of motion vector. If the detection of a motion vector is missed due to noise in one of the pixels of the block, the detection error of the motion vector cannot be determined. And the quality of moving image transmission and reproduction is degraded.

The present invention has been made in view of such a point, and simultaneously detects a motion vector of an image having a correlation with an image whose motion vector is to be detected, and performs comparison and evaluation to extract a motion vector detection error. It is another object of the present invention to provide a motion detecting device capable of correcting the motion.

[0009]

According to the motion detecting apparatus of the present invention, when detecting a motion vector of a continuous moving image, an odd / even field image of a frame used for motion vector detection is converted to a current odd field / current even number. Field and
The odd / even field image of the previous frame is referred to as a front odd field / front / even field, and the odd / even field image of the subsequent frame is referred to as a rear odd field / back even field. First motion vector detecting means for detecting a motion vector, second motion vector detecting means for detecting a motion vector between the current odd field and the subsequent odd field,
A third motion vector detecting means for detecting a motion vector between the previous even field and the current even field, a fourth motion vector detecting means for detecting a motion vector between the current even field and the rear even field, and a first motion The difference between the motion vectors obtained by the vector detecting means, the second motion vector detecting means, the third motion vector detecting means and the fourth motion vector detecting means is determined. And a correcting means for correcting a motion vector having a detection error to a correct value.

According to such a motion detecting device, the following operation is performed.

The first motion vector detecting means is supplied with the video signal data of the previous odd field and the video signal data of the current odd field. Therefore, the first motion vector detecting means detects the previous odd vector from the video signal data of the previous odd field and the video signal data of the current odd field.

Further, the second motion vector detecting means includes:
The video signal data of the current odd field and the video signal data of the subsequent odd field are supplied. Therefore, the second motion vector detecting means detects the rear odd vector from the video signal data of the current odd field and the video signal data of the rear odd field.

The third motion vector detecting means includes:
The video signal data of the previous even field and the video signal data of the current even field are supplied. Therefore, the third motion vector detecting means detects the previous even vector from the video signal data of the previous even field and the video signal data of the current even field.

The fourth motion vector detecting means includes:
The video signal data of the subsequent even field and the video signal data of the current even field are supplied. Therefore, the fourth motion vector detecting means detects a rear even vector from the video signal data of the rear even field and the video signal data of the current even field.

The difference between the front odd vector and the rear odd vector, the difference between the front odd vector and the front even vector, the difference between the front even vector and the rear odd vector, and the difference between the rear odd vector and the rear odd vector are calculated as follows. Each is calculated.

The evaluation means includes a vector value of a front odd vector, a rear odd vector, a front even vector, and a rear even vector, a sum of differences between block vectors in the vectors, and a difference between the calculated vectors. Supplied. Here, in the case of a series of images, it is sufficiently conceivable that there is a strong correlation between the motion vectors between the previous frame and the current frame and between the current frame and the subsequent frame. Also, when viewed on a field-by-field basis, it is fully conceivable that there is also a strong correlation between the motion vectors between the same frames of the odd and even fields. Therefore, the evaluation means and the correction means evaluate and correct the detection error of each vector, taking these factors into consideration.

An outline of a method for extracting a motion vector detection error in the vector evaluation means and the correction means will be described below. This method of extracting a motion vector detection error evaluates whether the difference value of the motion vector is larger or smaller than a predetermined threshold value.

First, when evaluating the vector of the current odd field, there is a time difference between the odd field and the even field. In this case, the vector value is temporally divided into a front odd vector, a front even vector, a rear odd vector, and a rear even number. It changes in the order of the vector. As described below, five cases can be evaluated by performing the evaluation.

Here, first, when the evaluation unit determines that the image of the image block is a still image based on the difference value of each vector detected by each motion vector detection unit, the front odd vector and the rear odd vector are determined. Are both values close to the 0 vector, and the difference value is equal to or less than a certain threshold value. Secondly, when the evaluation unit determines that the image of the image block is performing a constant-speed linear motion for two frames based on the difference value of each vector detected by each motion vector detection unit, the previous odd vector And the difference value between the odd odd vector and the rear odd number vector are equal to or smaller than a certain threshold.

That is, when the difference value between the front odd vector and the rear odd vector is below a certain threshold value, it is highly possible that the image of this image block is a still image or an image of a linear motion at a constant speed, and the reliability of the vector value is high. The gender is also higher than the one-direction vector.

On the other hand, when the difference value between the front odd vector and the rear odd vector is equal to or larger than a certain threshold value, the following cases can be considered.

Third, when the image of the image block is performing an acceleration linear motion in the evaluation means based on the difference value of each vector detected by each motion vector detection means, the amount of change of the vector changes with time. It is possible to judge whether the difference between the front odd vector and the front even vector, the difference between the front even vector and the rear odd vector, and the difference between the rear odd vector and the rear even vector change in an arithmetic series. it can.

Fourth, when the difference between the front vectors of the front odd vector and the front even vector, and the difference between the rear odd vector and the rear vector of the rear even vector are smaller than the threshold value, the front even vector and the rear odd vector If the difference between the vectors is also equal to or less than the threshold value, there is a possibility of the acceleration linear operation as described above, but if the vector difference between the front even vector and the rear odd vector is large, a scene change has occurred between frames. it is conceivable that. At this time, the correct vector direction can be determined, for example, as the direction in which the minimum value of the sum of the differences between the pixel values performed by the block matching of the front even vector and the rear odd vector is small.

Fifth, if one or both of the difference between the front vectors of the front odd vector and the front even vector, and the difference between the rear vectors of the rear odd vector and the rear even vector are equal to or larger than the threshold value, There may be a scene change between fields or a detection error. Here, when the difference between the three vectors including the front even vector and the rear even vector is less than or equal to the threshold value, it is determined that the distant vector value is a detection mistake and the other vector value is correct, It can be determined that the direction in which the minimum value of the sum of pixel value differences performed by matching is smaller is correct.

[0025]

The present embodiment will be described below. First, before describing the motion estimation device of the present embodiment, a description will be given of compression of a moving image and a motion vector which are prerequisites. The motion detection apparatus according to the present embodiment performs a motion compensation process before compressing image data in an encoding device such as a moving image encoding transmission device, and a decompression process of image data in a decoding device such as a high-definition television receiver. This is used to determine a motion vector when temporally filtering is performed in the post-filter that has been performed.

The input moving image must handle 30 images per second at a transfer rate of television broadcasting and 24 images of a movie. A feature of moving images is that they have temporal information. In other words, 1
The feature is that each video is not completely different but has many similar parts. That is, since a moving image has a high temporal correlation, compression using a temporal correlation between screens can be performed. This motion information is called a motion vector, and is obtained by performing subtraction between screens. This difference signal component is converted into D
By performing the CT conversion, the amount of data to be handled can be reduced. A moving image compression method that makes good use of the properties of this moving image is MPEG (Moving Picture).
Experts Group).

Hereinafter, the mechanism of MPEG will be described. MP
In the EG, the minimum unit of coding is called a picture, and defines three types. An I picture is data that can form a single image only with its own information. P picture and B picture are data that can reproduce the original video by using information of the preceding and following I pictures and P pictures.
A completed video cannot be composed only of a picture and a B picture. Therefore, random access is possible by inserting I pictures at appropriate intervals. Such a randomly accessible unit is referred to as a GOP (Group of
Pictures), one for about 15 pictures
Construct a GOP. This GOP is repeated to form a continuous sequence of a plurality of DCTs.

Here, at the time of encoding, motion compensation called bidirectional prediction is performed using information of a B picture.
Specifically, when an I picture is a past screen and a P picture is a future screen, not only forward prediction for predicting a future screen from a past screen from an I picture to a P picture, but also a P picture to an I picture A method of predicting an intermediate video B picture from both sides of backward prediction for predicting a past screen from a future screen is used. That is, P
Reverse prediction of an intermediate video from a future reproduced image from a picture to a B picture and forward prediction of an intermediate video from a past reproduced image from an I picture to a B picture are performed. Therefore, encoding and decoding are performed from I picture to P picture, P picture
The processing is performed in the order from a picture to a B picture. This order is
This means that the order of the original images and the order of the intermediate processing are different. MPEG stands for CD (Compact Disc)
It has been considered as an encoding standard for recording on storage media such as MPEG-2.
It has been studied from SC television broadcasting to digital television broadcasting such as HDTV (high definition).

The above-mentioned GOP is further divided into layers (layers).
Is divided into The GOP is composed of the above-described I picture, P picture, and B picture. One picture is subjected to component coding, in which a picture is separated into a luminance signal Y and two color difference signals Cb and Cr and can be encoded. However, the color difference signals Cb and Cr are one horizontal and one vertical compared to the luminance signal Y.
/ 2 sub-sampled. A picture is composed of slices. A slice is composed of a plurality of macro blocks. The macro block is a total of six blocks including four adjacent four blocks of the luminance signal Y, one color difference signal Cb block and one color difference signal Cr block corresponding to the four blocks. In this example, the minimum unit to be encoded is a block composed of 4 × 4 pixels. This block is a unit for performing DCT transform. This block is a unit to which the motion vector is applied in the motion detection device.

The motion detecting apparatus according to the present embodiment performs, in addition to the vector detection with the previous frame image, the backward motion vector detection by a method such as block matching with the image of the next frame of the image whose motion is to be detected. Then, the motion vector values before and after both the odd and even fields, which are obtained by using this, are stored, and the combined evaluation is performed. Is determined, and a correction value of the vector value is created from another vector value.

By doing so, the motion vector value of a certain block of the moving image is calculated between the frames before and after the block.
The evaluation is made from the vector values between the frames before and after the opposite field, so that detection errors can be reduced and a good reproduced image can be obtained.

First, the configuration of the motion detecting device according to the present embodiment will be described. In FIG. 1, the motion detection device includes a current frame image memory 4 for storing a current frame of an image frame, and a previous frame image memory for storing a frame of a time that is temporally advanced by one frame period from the current frame frame. A memory 7 and a memory 1 for a rear frame image for storing an image frame at a time point delayed by one frame period from the present time
And

The current frame image memory 4 has a current odd field storage area 6 and a current even field storage area 5, and the previous frame image memory 7 has a previous odd field storage area 9 and a previous even field storage area 8. And the rear frame image memory 1 has a rear odd field storage area 3 and a rear even field storage area 2
Having.

Further, the motion detecting apparatus includes a front odd field stored in a front odd field storage area 9 of a previous frame picture memory 7 and a current odd field stored in a current odd field storage area 6 of a current frame picture memory 4. A first motion vector detecting circuit 10 for detecting a previous odd vector od_fw from the odd field, and a current motion vector detecting circuit 10 for detecting a current odd field stored in a current odd field storage area 6 of a current frame image memory 4 and a memory for a subsequent frame image 1 And a second motion vector detection circuit 11 for detecting a rear odd vector od_bw from the rear odd field stored in the odd field storage area 3. The above-described motion vector detection circuits 10 and 11 are configured by algorithm circuits such as block matching described later. Here, the first motion vector detection circuit 10 includes first motion vector detection means,
The second motion vector detection circuit 11 constitutes second motion vector detection means.

Further, the motion detecting apparatus includes a previous even field stored in the previous even field storage area 8 of the previous frame image memory 7 and a current even field stored in the current even field storage area 5 of the current frame image memory 4. A third motion vector detecting circuit 12 for detecting a previous even vector ev_fw from the even field, a current data of the rear even field and the current frame image memory 4 stored in the rear even field storage area 2 of the subsequent frame image memory 1; And a fourth motion vector detection circuit 13 for detecting the subsequent even vector ev_bw from the current even field stored in the even field storage area 5. Here, the vector value of each vector is set such that the moving direction from the rear frame to the previous frame of the image frame is the positive direction. The above-described motion vector detection circuits 12 and 13 are configured by algorithm circuits such as block matching. Here, the first motion vector detection circuit 10 constitutes first motion vector detection means, and the second motion vector detection circuit 11 constitutes second motion vector detection means.

The motion detecting apparatus has an evaluation block 15 for evaluating each vector from a front odd vector od_fw, a rear odd vector od_bw, a front even vector ev_fw, and a rear even vector ev_bw. Here, the evaluation block 15 calculates the previous odd vector od_fw,
Rear odd vector od_bw, front even vector ev_fw
And a difference calculation circuit 16 for calculating a difference between the rear even vector ev_bw.

Further, the motion detecting apparatus calculates the sum of the difference between the vector values of the front odd vector od_fw, the rear odd vector od_bw, the front even vector ev_fw, and the rear even vector ev_bw, and the difference between the block pixel values in the vector and the difference operation. A vector evaluation / correction circuit 17 that evaluates and corrects a detection error of each vector using the difference between each vector calculated by the circuit 16 is provided. Here, the vector evaluation / correction circuit 17 determines a difference between the motion vectors, and when the value is larger than a predetermined threshold value, determines a motion vector that has made a detection error, and makes a detection error. Correction means for correcting the motion vector to a correct value. The vector evaluation / correction circuit 17 is composed of, for example, software operating on a CPU (central processing unit), a ROM (read only memory), and a RAM (random access memory). The operation of the thus configured motion estimation device of the present embodiment will be described below.
Hereinafter, an operation in a case where the present invention is applied to a video signal after a compressed moving image signal has undergone expansion processing in a decoding device will be described.

In FIG. 1, an input video signal is stored in a memory 1 for a subsequent frame image. At the same time, the video signal data stored in the memory 1 for the subsequent frame image is stored in the memory 4 for the current frame image, and the video signal data stored in the memory 4 for the current frame image is sequentially stored in the memory 7 for the previous frame image. Sent and stored.

At this time, the video signal data of the odd field and the even field of the subsequent frame are stored in the rear odd field storage area 3 and the rear even field storage area 2 in the memory 1 for the current frame image. In the current odd field storage area 6 and the current even field storage area 5, the video signal data of the odd field and the even field of the current frame are stored. In the previous frame image memory 7, the previous odd field storage area 9 and the previous even field are stored. The area 8 stores the video signal data of the odd field and the even field of the previous frame.

The first motion vector detecting circuit 10 stores the video signal data of the previous odd field stored in the previous odd field storage area 9 of the previous frame picture memory 7 and the current odd field of the current frame picture memory 4. The video signal data of the current odd field stored in the area 6 is supplied. Therefore, the first motion vector detection circuit 10
, The video signal data of the previous odd field stored in the previous odd field storage area 9 of the previous frame image memory 7 and the video signal of the current odd field stored in the current odd field storage area 6 of the current frame image memory 4 The previous odd vector od_fw is detected from the data.

The second motion vector detecting circuit 11 stores the video signal data of the current odd field stored in the current odd field storage area 6 of the current frame picture memory 4 and the rear odd number of the subsequent frame picture memory 1. After being stored in the field storage area 3, video signal data of an odd field is supplied. Therefore, in the second motion vector detecting circuit 11, the video signal data of the current odd field stored in the current odd field storage area 6 of the current frame picture memory 4 and the rear odd field storage area 3 of the subsequent frame picture memory 1 are stored. , A rear odd vector od_bw is detected from the video signal data of the rear odd field stored in.

Further, the third motion vector detecting circuit 12 stores the video signal data of the previous even field stored in the previous even field storage area 8 of the previous frame picture memory 7 and the current even number of the current frame picture memory 4. The video signal data of the current even field stored in the field storage area 5 is supplied. Therefore, in the third motion vector detecting circuit 12, the video signal data of the previous even field stored in the previous even field storage area 8 of the previous frame image memory 7 and the current even field storage area 5 of the current frame image memory 4 are stored. And the previous even vector ev_fw is detected from the video signal data of the current even field stored in.

Further, the fourth motion vector detecting circuit 13 stores the video signal data of the subsequent even field stored in the rear even field storage area 2 of the subsequent frame image memory 1 and the current even number of the current frame image memory 4. The video signal data of the current even field stored in the field storage area 5 is supplied. Therefore, in the fourth motion vector detecting circuit 13, the video signal data of the rear even field stored in the rear even field storage area 2 of the rear frame image memory 1 and the current even field storage area 5 of the current frame image memory 4 are stored. And the subsequent even-number vector ev_bw is detected from the video signal data of the current even-number field stored in.

Here, each of the motion vector detecting circuits 10-1
3 will be described. The block matching method divides a screen into small rectangular areas (blocks) and detects motion for each block. The size of this block is 8 × 8 pixels, 1
6 × 16 pixels or the like are used. For example, with respect to the block of the previous frame as a reference frame at the same position as the block Bj at the position (i, j) of the current frame, ±
From the position (i, j) within the search range of m × ± n pixels, (x,
The sum of the difference between the absolute value of each pixel and the block shifted by y) is calculated, and the shift amount v = (x, y) that becomes the minimum value
Is a motion vector.

The difference calculation circuit 16 of the evaluation block 15 includes a front odd vector od_fw and a rear odd vector od_fw.
bw, a front even vector ev_fw and a rear even vector ev_bw are provided. In the difference calculation circuit 16, the front odd vector od_fw and the rear odd vector od_fw
bw, the difference between the front odd vector od_fw and the front even vector ev_fw, the difference between the front even vector ev_fw and the rear odd vector od_bw, and the rear odd vector o
The difference between d_bw and the rear odd vector od_bw is calculated.

The vector evaluation / correction circuit 17 of the evaluation block 15 includes a vector value of a front odd vector od_fw, a rear odd vector od_bw, a front even vector ev_fw, and a rear even vector ev_bw, and a difference between a block pixel value and the vector value of the vector. The sum and the difference of each vector calculated by the difference calculation circuit 16 are supplied. Here, in the case of a series of images, it is sufficiently conceivable that there is a strong correlation between the motion vectors between the previous frame and the current frame and between the current frame and the subsequent frame. Also, when viewed on a field-by-field basis, it is fully conceivable that there is also a strong correlation between the motion vectors between the same frames of the odd and even fields. Therefore, the vector evaluation / correction circuit 17 evaluates and corrects the detection error of each vector, taking these factors into consideration. In this case, the corrected value may be further evaluated. An outline of a method of extracting a motion vector detection error in the vector evaluation / correction circuit 17 will be described below. This method of extracting a motion vector detection error evaluates whether the difference value of the motion vector is larger or smaller than a predetermined threshold value.

First, a case where an interlaced video having a vertical frequency fv [Hz] is used as a signal source and the vector of the current odd field is evaluated will be described with reference to FIG. In FIG. 2, between the previous odd field 27 and the previous even field 28 of the previous frame 26, between the previous even field 28 of the previous frame 26 and the current odd field 24 of the current frame 23, and the current odd field 24 of the current frame 23. There is a time difference of 1 / fv seconds between the current even field 25 and the current even field 25. In this case, the vector values are temporally odd odd vector od_fw, previous even vector ev_fw, odd odd vector od_bw, and even even vector ev_bw. It changes in order. It is evaluated by 5 as follows.
Two cases can be evaluated.

First, the evaluation block 15 determines that the image of the image block is a still image on the basis of the difference between the vectors detected by the motion vector detection circuits 10 to 13 of the motion detection block 14. In this case, both vector values of the front odd vector od_fw and the rear odd vector od_bw are close to the zero vector, and the difference value is equal to or less than a certain threshold. Second, the motion detection block 1
Also, when it is determined in the evaluation block 15 that the image of the image block is performing a constant-speed linear operation for two frames based on the difference value of each vector detected by each of the motion vector detection circuits 10 to 13 of FIG. The difference value between od_fw and the rear odd number vector od_bw is equal to or less than a certain threshold value.

That is, when the difference value between the front odd vector od_fw and the rear odd vector od_bw is equal to or less than a certain threshold value, it is highly possible that the image of this image block is a still image or an image of a linear motion at a constant speed. Is also higher than the one-direction vector.

On the other hand, when the difference between the front odd vector od_fw and the rear odd vector od_bw is equal to or larger than a certain threshold value, the following cases can be considered.

Third, when the image of the image block performs the linear acceleration operation in the evaluation block 15 based on the difference value of each vector detected by each of the motion vector detection circuits 10 to 13 of the motion detection block 14, the time Since the amount of change of the vector changes, the previous odd vector od
_Fw and the difference between the front even vector ev_fw, the difference between the front even vector ev_fw and the rear odd vector od_bw, the rear odd vector od_bw and the rear even vector ev_
bw can be determined based on whether or not the difference has changed in an arithmetic progression.

Fourth, the difference between the front vector of the front odd vector od_fw and the front even vector ev_fw and the difference of the rear vector between the rear odd vector od_bw and the rear even vector ev_bw are also equal to or smaller than the threshold value. If the vector difference between ev_fw and the rear odd vector od_bw is also equal to or smaller than the threshold value, there is a possibility that the acceleration linear operation is performed as described above.
If the vector difference between _fw and the rear odd vector od_bw is large, it is considered that a scene change has occurred between frames. At this time, as the correct vector direction, for example, the front even vector ev_fw and the rear odd vector od_b
It can be obtained as the direction in which the minimum value of the sum of the pixel value differences performed in the block matching of w is smaller.

Fifth, one or both of the difference between the front odd vector od_fw and the front vector of the front even vector ev_fw and the difference between the rear odd vector od_bw and the rear vector of the rear even vector ev_bw are equal to or larger than the threshold value. In the case of, there is a possibility that a scene change has occurred between fields or a detection error has occurred. Here, if the difference between the three vectors, including the vector of the even-numbered vector ev_fw and the vector of the even-numbered vector ev_bw, is equal to or smaller than the threshold value, it is assumed that the distant vector value is a detection error and the other vector value is correct. , The direction in which the minimum value of the sum of pixel value differences performed in block matching is small can be determined as correct.

Hereinafter, the operation of the motion detecting apparatus according to the present embodiment will be described with reference to a specific flowchart when the threshold value of the difference value of the motion vector is set to “1”.

In step S1, each of the motion vector detection circuits 10 to 13 of the detection block 14 outputs
_Fw, front even vector ev_fw, rear odd vector o
Each motion vector of d_bw and the subsequent even vector ev_bw is detected.

In step S2, the difference calculation circuit 16 of the evaluation block 15 calculates a difference value between the front odd vector od_fw and the rear odd vector od_bw, and the vector evaluation / correction circuit 17 of the evaluation block 15 calculates the front odd vector od_f.
It is determined whether or not the absolute value of the difference value between w and the rear odd vector od_bw is “1” or less.

In step S2, the vector evaluation / correction circuit 17 of the evaluation block 15 determines that the absolute value of the difference value is "1".
If it is determined that it is below, the process proceeds to step S3. In step S3, the vector evaluation / correction circuit 17 of the evaluation block 15 determines the front odd vector od_fw and the rear odd vector o.
It is determined whether each vector value of d_bw is close to “0”. In step S3, the vector evaluation / correction circuit 17 of the evaluation block 15 sets these vector values to "0".
When it is determined that it is close to the above, the process proceeds to step S4. In step S4, as a first case, the vector evaluation / correction circuit of the evaluation block determines that the image of the image block is a still image. At this time, in step S5, the vector evaluation / correction circuit of the evaluation block determines that the vector value detected by the motion detection block 14 is correct for both the front odd vector od_fw and the rear odd vector od_bw.

In step S3, the evaluation block 15
When the vector evaluation / correction circuit 17 determines that these vector values are not close to "0", the process proceeds to step S6. In step S6, as a second case, the vector evaluation / correction circuit 17 of the evaluation block 15 determines that the image of the image block is performing a uniform linear operation. At this time, in step S7, the vector evaluation / correction circuit 17 of the evaluation block 15 determines that the vector values detected by the motion detection block 14 are a front odd vector od_fw and a rear odd vector od.
_Bw are determined to be correct.

As described above, when the difference between the front odd vector od_fw and the rear odd vector od_bw is equal to or less than a certain threshold, the image of this image block is a still image or a second image as in the first case described above. Thus, it can be determined that the image is a linear motion image.

On the other hand, when the difference between the front odd vector od_fw and the rear odd vector od_bw is equal to or greater than a certain threshold value, the case can be further divided as described later.

In step S2, the vector evaluation / correction circuit 17 of the evaluation block 15 determines that the absolute value of the difference value is "1".
If it is determined that it is larger than the above, the process proceeds to step S8. In step S8, the difference calculation circuit 16 of the evaluation block 15
Are the front odd vector od_fw and the front even vector ev_
fw, the difference β between the front even vector ev_fw and the rear odd vector od_bw, the rear odd vector od_b
and the difference の between w and the even number vector ev_bw is calculated.

In step S9, the vector evaluation / correction circuit 17 of the evaluation block 15 determines whether (α-β) = (β-χ) based on each difference value obtained in step S8. . If the vector evaluation / correction circuit 17 of the evaluation block 15 determines in step S9 that (α−β) = (β−χ), the process proceeds to step S10. Step S
10, the vector evaluation / correction circuit 1 of the evaluation block 15
7 determines that the image of the image block is performing a constant speed linear operation. At this time, in step S11, the vector evaluation / correction circuit 17 of the evaluation block 15 determines that the vector value detected by the motion detection block 14 is the previous odd vector od_
It is determined that both fw and the later odd number vector od_bw are correct.

If the vector evaluation / correction circuit 17 of the evaluation block 15 determines in step S9 that (α-β) = (β-χ), the flow advances to step S12. Step S
12, the vector evaluation / correction circuit 1 of the evaluation block 15
7 is a front odd vector od_fw and a front even vector ev
It is determined whether or not the absolute value of the difference from _fw is equal to or smaller than “1” and the absolute value of the difference between the rear odd vector od_bw and the rear even vector ev_bw is equal to or smaller than “1”.
In step S12, the vector evaluation /
When the correction circuit 17 determines that the absolute values of the differences between these vectors are both equal to or smaller than “1”, step S13
Proceed to.

In step S13, the vector evaluation / correction circuit 17 of the evaluation block 15 outputs the previous even vector ev_f
It is determined whether or not both the absolute value of the difference between w and the rear odd vector od_bw is equal to or less than “1”. Step S13
The vector evaluation / correction circuit 17 of the evaluation block 15
However, when it is determined that the absolute value of the difference between the vectors is “1” or less, the process proceeds to step S14. Step S1
4, the vector evaluation / correction circuit 17 of the evaluation block 15
Third, it is determined that the image of the image block may be performing an acceleration linear motion.

In this case, since the amount of change of the vector changes with time, the difference between the previous odd vector od_fw and the previous even vector ev_fw, and the previous even vector ev_f
It can be determined that the difference between w and the rear odd vector od_bw and the difference between the rear odd vector od_bw and the rear even vector ev_bw change in an arithmetic progression.

At this time, in step S15, the vector evaluation / correction circuit 17 of the evaluation block 15 determines that the detected motion vector value may be correct. Also,
In step S16, the vector evaluation /
The correction circuit 17 determines that the vector in the direction in which the sum of the pixel value differences obtained by the block matching when detecting the four motion vectors in step S1 is small is correct. In this case, the values of the motion vectors in the four directions are very close between the preceding and succeeding frames and between the odd or even fields. Therefore, the detection accuracy can be further improved by the process of step S16.

In step S13, when the vector evaluation / correction circuit 17 of the evaluation block 15 determines that the absolute value of the difference between the vectors is not smaller than "1", the flow proceeds to step S13.
Proceed to 17. Fourth, in step S17, the vector evaluation / correction circuit 17 of the evaluation block 15 determines that the image of the image block may have a scene change between frames.

At this time, in step S18, the vector evaluation / correction circuit 17 of the evaluation block 15
It is determined that the vector in the direction in which the sum of the pixel value differences obtained by the block matching when detecting the four motion vectors is small is correct. In this case, the values of the motion vectors in the four directions are close between the preceding and succeeding frames, but there is a difference between the odd and even fields. This makes it possible to reliably correct a motion vector for which a detection error has occurred, even between odd and even fields. In step S12, the vector evaluation / correction circuit 17 of the evaluation block 15 determines whether the previous odd vector od_fw and the previous even vector e
If it is determined that one or both of the difference from v_fw and the absolute value of the difference between the rear odd vector od_bw and the rear even vector ev_bw are not “1” or less, the process proceeds to step S19.

Fifth, in step S19, the vector evaluation / correction circuit 17 of the evaluation block 15 determines, fifthly, that a scene change has occurred between fields or that a vector detection error has occurred. Here, in step S20, 4
If the values of the three vectors in the vectors are close to each other and only one vector is separated, the separated vector values are determined to be detection errors.

At this time, in step S21, the vector evaluation / correction circuit 17 of the evaluation block 15
The previous even number vector e when detecting the four motion vectors
It is determined that the vector in the direction in which the sum of the pixel values obtained by performing block matching between v_fw and the rear odd vector od_bw is small is correct. In this case, there is a difference between the values of the motion vectors in the four directions between the preceding and succeeding frames, but there is also a difference between the odd and even fields, and the values of the motion vectors in the four directions are different. In this case, a detection error is reliably detected by assuming that the closer to the odd field or even field of the current frame is correct, of the front and even vector ev_fw and the rear odd vector od_bw which are vector values before and after the current frame. The motion vector can be corrected to the correct value.

As described above, according to the motion detecting apparatus of the present embodiment described above, the reliability of the detected motion vector is determined, and the vector value determined as a detection error is changed to a value determined to be correct. Since the mosquito distortion is corrected, mosquito distortion during image compression can be improved, and a good reproduced image can be obtained.

Here, the mosquito distortion is peculiar to the DCT transformation, and a base image indicating the coefficient after the DCT transformation remains after the quantization, and the fly is caused by the corona effect around the edge of the base image. Distortion that looks like flying. This mosquito distortion changes with time and becomes annoying noise. This mosquito distortion increases as the frequency f increases. This is because the noise component that looks like mosquito distortion mainly depends on the quantization matrix of the inverse quantization of the decompression processing unit.

As a method for suppressing such image quality deterioration, a motion compensating unit is provided as a pre-process in a coding device before the compression processing unit, and the motion compensation is performed on the input image before the input image is compressed. A method of performing processing to improve the final image quality is adopted. Similarly, a post-filter is provided as post-processing in the decoding device after the compression processing unit, and after the output image is decompressed, a spatial filter is applied to the output image to eliminate noise and pixel omission. A method of improving the typical image quality is adopted.

When a motion vector is determined in such a motion compensator and a post filter, the motion detection device of this embodiment judges whether each motion vector is appropriate and makes a detection error. By correcting the vector value to a vector value determined to be correct, mosquito distortion can be improved and the image quality of a reproduced image can be improved.

Here, an encoding device using the motion compensation unit and a decoding device using the post filter will be described.

The encoding device has an encoding control unit for controlling the quantization characteristics, a DCT conversion circuit for converting a time component into a frequency component, and a quantization circuit for quantizing the DCT-transformed DCT coefficients. Further, the encoding device includes an inverse quantization circuit, an inverse DCT transform circuit, a motion compensator, and a loop filter. Here, the motion compensation unit corresponds to the motion detection device according to the present embodiment. The loop filter is a pre-filter and removes high frequency components in advance.

In the coding apparatus configured as described above, the image signal data motion-compensated and predicted is subjected to the DCT transform in the DCT transform circuit, and the DCT transform is performed in the quantizing circuit.
The T coefficient is quantized. Here, the motion compensation prediction will be described. In a memory having a variable delay mechanism for motion compensation, a motion vector is detected from data before image compression processing as in the above-described embodiment. At this time, the motion vectors in the four directions described above are used when compensating the motion of the same pixel of the 8 × 8 pixel block with respect to the data before the image compression processing. In this manner, the pixel information before and after and the image information are interpolated, thereby preventing pixel omission and the like.

The decoding device has an inverse quantization circuit for performing inverse quantization and an inverse DC for inversely transforming frequency components into time components.
A T conversion circuit. Further, the decoding device includes a memory having a variable delay mechanism for motion compensation, and a loop filter. Here, the memory having the variable delay mechanism for motion compensation corresponds to the motion detecting device of the present embodiment, and the loop filter corresponds to the post filter.

In the decoding apparatus thus configured, the image signal data subjected to the image compression processing is inversely quantized by the inverse quantization circuit, inverse DCT-transformed by the inverse DCT transformation circuit, and subjected to image expansion processing. You. Motion compensation prediction is performed on the image signal data subjected to the image expansion processing. Here, the motion compensation prediction will be described. In the memory having the variable delay mechanism for motion compensation, motion vectors in four directions are detected from the image data after the image decompression processing as in the above-described embodiment. In the post-filter, 8 × 8 for the image data after the image expansion processing
It operates as a two-dimensional spatial filter closed to a pixel block. At this time, the post filter uses the above-described four-directional motion vectors to perform the previous frame 26 (the previous odd field 27 or the previous even field 28) and the current frame 23 (the current odd field 24 or the current even field 25) shown in FIG. During the current frame 23 (current odd field 24)
Alternatively, it operates as a temporal filter between the current even field 25) and the subsequent frame 20 (the rear odd field 21 or the rear even field 22). That is, the post-filter includes the previous frame 26 (the previous odd field 27 or the previous even field 28), the current frame 23 (the current odd field 24 or the current even field 25), and the subsequent frame 20 (the rear odd field 21 or the rear even field 22). ) Is applied with a filter coefficient of (１ ／, ４ ，, １ ／). This post filter is a low-pass type. The filter coefficient is (1 /
2, 1/4, 1/2) but (0, 1, 0) at the end of the block. The result of the filter is rounded and converted to an integer. The filter is turned on / off for each macroblock. The ON / OFF information is determined by the macroblock type. The filter coefficient is (1/2, 1/4, 1/2) at the upper end and lower end of the image, but (1/2, 1, 1/2) at the center of the image. The four corners of the image are (1,1,1). This is because the center and four corners of the image have relatively little mosquito distortion due to DCT transform. In the decoding device, one motion vector is decoded per macroblock.

As described above, when detecting the motion vector of a continuous moving image, the motion detecting apparatus of the present embodiment converts the odd / even field image of the frame used for motion vector detection into the current odd field / current even field. Field and
The odd / even field image of the previous frame is referred to as a front odd field / front / even field, and the odd / even field image of the subsequent frame is referred to as a rear odd field / back even field. A first motion vector detecting means 10 for detecting a front odd vector od_fw of a motion vector, a second motion vector detecting means 11 for detecting a rear odd vector od_bw between a current odd field and a rear odd field, Third detection of the previous even vector ev_fw of the motion vector between the even field and the current even field
Of the motion vector between the current even field and the rear even field,
_Bw, a fourth motion vector detecting means 13 for detecting
The difference between the motion vectors obtained by the first motion vector detecting means 10, the second motion vector detecting means 11, the third motion vector detecting means 12, and the fourth motion vector detecting means 13 is calculated, and the difference is calculated. Evaluation / correction circuit 1 as a judging means for finding a motion vector having a detection error when is larger than a predetermined threshold value
And a vector evaluation / correction circuit 1 as correction means for correcting the motion vector having the detection error to a correct value.
7 and so on, between the previous odd field and the current odd field, between the current odd field and the subsequent odd field, between the previous even field and the current even field, and between the current even field and the current even field.
After detecting each motion vector between the even-numbered fields, calculating the difference between the motion vector windings, finding a vector that has been detected incorrectly according to the magnitude of the value, and correcting the vector value to a correct value, It is possible to reduce the detection error of the motion vector in the image reproducing device of the image encoding transmission device, and obtain a good reproduced image.

In the motion detecting apparatus according to the present embodiment, in the above description, the vector evaluation / correction circuit 17 as the determining means includes at least the first motion vector detecting means 10 and the second motion vector detecting means. The difference between the motion vectors by the means 11 and the difference between the motion vectors by the third motion vector detecting means 12 and the second motion vector detecting means 11 are determined. Since it is determined that there is a scene change between the frames, it is possible to determine whether there is a vector detection error or a scene change based on the difference between frames.

In the motion detecting apparatus according to the present embodiment, in the above description, the vector evaluation / correction circuit 17 as the judging means includes at least the first motion vector detecting means 10 and the second motion vector estimating means. The difference between the motion vectors obtained by the means 11 and the difference between the motion vectors obtained by the third motion vector detection means 12 and the second motion vector detection means 11 are obtained. The first motion vector detecting means 1
0, the motion vector having the smaller total sum of the pixel values obtained by the block matching in the second motion vector detecting means 11 and the third motion vector detecting means 12 is determined to be correct. Even in the case of a change, a correct motion vector value can be obtained. Further, in the motion estimation device of the present embodiment, in the above description, the vector evaluation / correction circuit 17 as the determination means includes at least the first motion vector detection means 10 and the second motion vector detection means 11 , The difference between the motion vectors by the first motion vector detecting means 10 and the third motion vector detecting means 12, the second motion vector detecting means 1
1 and the motion vector difference obtained by the fourth motion vector detecting means 13 are calculated. When the difference is larger than a predetermined threshold value, whether a scene change has occurred between fields or a motion vector detection error is detected. Therefore, it is possible to determine a scene change and a detection error between fields based on a difference between the fields.

In the motion detecting apparatus according to the present embodiment, in the above description, the vector evaluation / correction circuit 17 serving as the determining means includes at least the first motion vector detecting means 10 and the second motion vector detecting means. The difference between the motion vectors by means 11, the difference between the motion vectors by the first motion vector detecting means 10 and the third motion vector detecting means 12, the difference between the second motion vector detecting means 11 and the fourth motion The difference between the motion vectors obtained by the vector detecting means 13 is obtained. When the difference is larger than a predetermined threshold value, the values of three of the four motion vectors are close to each other, If only the vector values are distant, it is determined that the other one motion vector has been detected incorrectly. Even if the Nji and detection error, it is possible to find the detection error from the correlation of the four motion vectors.

In the motion detecting apparatus according to the present embodiment, in the above description, the vector evaluation / correction circuit 17 as the determining means includes at least the first motion vector detecting means 10 and the second motion vector detecting means 10. The difference between the motion vectors by the means 11, the difference between the motion vectors by the first motion vector detecting means 10 and the third motion vector detecting means 12, the difference between the second motion vector detecting means 12 and the fourth motion The difference between the motion vectors by the vector detecting means 13 is obtained, and when the difference is larger than a predetermined threshold value, the first motion vector detecting means 10,
Since it is determined that the motion vector having the smaller total sum of the pixel values obtained by the block matching in the second motion vector detecting means 11 is correct, even if a scene change between fields and a detection error occur, A correct motion vector value can be obtained.

[0085]

According to the motion detecting apparatus of the present invention, when detecting a motion vector of a continuous moving image, an odd / even field image of a frame used for motion vector detection is set to a current odd field / current even field. Replace the odd / even field image of the previous frame with the previous odd field /
First motion vector detecting means for detecting a motion vector between a front odd field and a current odd field by setting a front / even field and an odd / even field image of a rear frame as a rear odd field / back even field; A second motion vector detecting means for detecting a motion vector between the field and the subsequent odd field; and a third motion vector for detecting a motion vector between the previous even field and the current even field.
Motion vector detecting means, fourth motion vector detecting means for detecting a motion vector between the current even field and subsequent even field, the first motion vector detecting means, the second motion vector detecting means, Determining a difference between the motion vectors obtained by the third motion vector detecting means and the fourth motion vector detecting means, and determining a motion vector having a detection error when the difference is larger than a predetermined threshold value; Since the correction means for correcting the motion vector having the detection error to a correct value is provided,
Each motion vector between the previous odd field and the current odd field, between the current odd field and the subsequent odd field, between the previous even field and the current even field, and between the current even field and the rear even field is detected, and the difference between the motion vector windings is detected. Is found, a vector having a detection error due to the magnitude of the value is found, and the vector value is corrected to a correct value, thereby reducing a motion vector detection error in the image reproduction device of the moving image encoding transmission device, and This produces an effect that a proper reproduced image can be obtained.

Further, in the motion detecting apparatus according to the present invention, in the above, the judging means comprises: at least a difference between motion vectors obtained by the first motion vector detecting means and the second motion vector detecting means; The difference between the motion vectors obtained by the motion vector detecting means and the second motion vector detecting means is obtained. When the difference is larger than a predetermined threshold value, it is determined that a scene change has occurred between frames. Thus, it is possible to determine whether a vector detection error or a scene change has occurred based on the difference between the two.

Further, in the motion detecting apparatus according to the present invention, in the above, the judging means includes at least a difference between motion vectors obtained by the first motion vector detecting means and the second motion vector detecting means; The difference between the motion vectors obtained by the motion vector detecting means and the second motion vector detecting means is obtained. When the difference is larger than a predetermined threshold value, the first motion vector detecting means and the second motion vector Since the motion vector having the smaller total sum of the pixel values obtained by the block matching in the vector detecting means and the third motion vector detecting means is determined to be correct, the correct motion vector is obtained even when the scene changes between frames. Is obtained.

Further, in the motion detecting apparatus according to the present invention, in the above, the judging means comprises at least a difference between the motion vectors obtained by the first motion vector detecting means and the second motion vector detecting means; The difference between the motion vectors obtained by the motion vector detecting means and the third motion vector detecting means and the difference between the motion vectors obtained by the second motion vector detecting means and the fourth motion vector detecting means are obtained. When the value is larger than a predetermined threshold, whether the scene has changed between fields,
Since it is determined that a motion vector has been detected incorrectly, it is possible to determine a scene change between fields and a detection error based on a difference between fields.

Further, in the motion detecting apparatus according to the present invention, in the above, the judging means includes at least a difference between motion vectors obtained by the first motion vector detecting means and the second motion vector detecting means; The difference between the motion vectors obtained by the motion vector detecting means and the third motion vector detecting means and the difference between the motion vectors obtained by the second motion vector detecting means and the fourth motion vector detecting means are obtained. When the value of the three motion vectors is close to each other when the value is larger than the predetermined threshold value and only the value of the other one motion vector is distant, the other one Since it is determined that a motion vector has been detected incorrectly, even if there is a scene change between fields and a detection error has occurred, the phase of the four motion vectors is determined. An effect that it is possible to find a detection error from.

Further, in the motion detecting apparatus according to the present invention, in the above, the judging means includes at least a difference between motion vectors obtained by the first motion vector detecting means and the second motion vector detecting means; The difference between the motion vectors obtained by the motion vector detecting means and the third motion vector detecting means and the difference between the motion vectors obtained by the second motion vector detecting means and the fourth motion vector detecting means are obtained. When the threshold value is larger than the predetermined threshold value, it is determined that the motion vector having the smaller total sum of the pixel value differences obtained by the block matching in the first motion vector detecting means and the second motion vector detecting means is correct. Therefore, even when a scene change between fields and a detection error occur, a correct motion vector value can be obtained. The effect say.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a motion detection device according to the present embodiment.

FIG. 2 is a diagram illustrating an operation of the motion detection device according to the present embodiment.

FIG. 3 is a flowchart illustrating an operation of the motion detection device according to the present embodiment.

FIG. 4 is a flowchart illustrating an operation of the motion detection device according to the present embodiment.

FIG. 5 is a flowchart illustrating an operation of the motion detection device according to the present embodiment.

FIG. 6 is a flowchart illustrating an operation of the motion detection device according to the present embodiment.

FIG. 7 is a flowchart illustrating an operation of the motion detection device according to the present embodiment.

[Explanation of symbols]

1 Memory for rear frame image, 2 Even field storage area after 3, 3 Odd field storage area, 4 Current frame image memory, 5 Current even field storage area, 6 Current odd field storage area, 7 Memory for previous frame image, 8 Previous even field storage area, 9 Previous odd field storage area, 10 motion vector detection circuit, 11 motion vector detection circuit, 12 motion vector detection circuit, 13 motion vector detection circuit, 14 motion detection block, 15 evaluation block, 16 difference calculation circuit , 17 vector evaluation and correction circuit, 20 post-frame, 21 post-odd field, 22 post-even field,
23 current frame, 24 current odd field, 25 current even field, 26 previous frame, 27 previous odd field, 28 previous even field, od_fw previous odd vector, odd_bw after odd vector, ev_fw before even vector, ev_bw after even vector

Claims (6)

[Claims] When detecting a motion vector of a continuous moving image, an odd / even field image of a frame used for detecting a motion vector is defined as a current odd field / current even field, and an odd / even field of a preceding frame is detected. A first motion for detecting a motion vector between a front odd field and a current odd field, where an image is a front odd field / front even field, an odd / even field image of a subsequent frame is a rear odd field / back even field, Vector detection means, second motion vector detection means for detecting a motion vector between the current odd field and subsequent odd field, and third motion vector detection means for detecting a motion vector between the previous even field and the current even field. 4th detecting a motion vector between the current even field and the succeeding even field Calculating a motion vector difference between the motion vector detecting means, the first motion vector detecting means, the second motion vector detecting means, the third motion vector detecting means, and the fourth motion vector detecting means; Motion detection comprising: a determination means for finding a motion vector having a detection error when the value is larger than a predetermined threshold value; and a correction means for correcting the motion vector having a detection error to a correct value. apparatus. 2. The motion detecting device according to claim 1, wherein said determining means includes at least a difference between motion vectors obtained by said first motion vector detecting means and said second motion vector detecting means; A difference between motion vectors obtained by the motion vector detecting means and the second motion vector detecting means is obtained, and when the value is larger than a predetermined threshold value, it is determined that a scene change has occurred between frames. Motion detection device. 3. The motion detecting device according to claim 1, wherein said determining means includes: at least a difference between motion vectors obtained by said first motion vector detecting means and said second motion vector detecting means; A difference between motion vectors obtained by the motion vector detecting means and the second motion vector detecting means is obtained. When the difference is larger than a predetermined threshold value, the first motion vector detecting means, the second motion vector A motion detecting apparatus, wherein a motion vector having a smaller sum of pixel value differences obtained by block matching in the detecting means and the third motion vector detecting means is determined to be correct. 4. The motion detection device according to claim 1, wherein the determination means includes at least a difference between motion vectors obtained by the first motion vector detection means and the second motion vector detection means, The difference between the motion vectors obtained by the motion vector detecting means and the third motion vector detecting means, and the difference between the motion vectors obtained by the second motion vector detecting means and the fourth motion vector detecting means are determined. A motion detection device that determines that a scene change has occurred between fields and that a motion vector has been detected incorrectly when the threshold value is larger than the threshold value. 5. The motion detection device according to claim 1, wherein the determination means includes at least a difference between a motion vector obtained by the first motion vector detection means and a motion vector obtained by the second motion vector detection means. The difference between the motion vectors obtained by the motion vector detecting means and the third motion vector detecting means, and the difference between the motion vectors obtained by the second motion vector detecting means and the fourth motion vector detecting means are determined. When the values of the three motion vectors among the four motion vectors are close to each other and only the value of the other one motion vector is distant, the other one of the motion vectors A motion detection device that determines that a detection error has occurred in a vector. 6. The motion detecting device according to claim 1, wherein said determining means includes at least a difference between motion vectors obtained by said first motion vector detecting means and said second motion vector detecting means. The difference between the motion vectors obtained by the motion vector detecting means and the third motion vector detecting means, and the difference between the motion vectors obtained by the second motion vector detecting means and the fourth motion vector detecting means are determined. When the threshold value is larger than the threshold value, it is determined that the motion vector in which the total sum of the pixel value differences obtained by the block matching in the first motion vector detecting means and the second motion vector detecting means is smaller is correct. A motion detection device characterized by the above-mentioned.