JPH06217266A - Motion vector detecting circuit - Google Patents

Abstract

PURPOSE:To precisely detect a motion vector with simple constitution. CONSTITUTION:An initial deviation vector selecting circuit 1 finds an initial deviation vector V0. A 1st gradient method arithmetic circuit 2 finds a deviation quantity V1 from V0. A 2nd gradient method arithmetic circuit 3 finds a deviation quantity V2 from (V0+V1). A comparing circuit 4 makes an evaluating circuit 5 select and output (V0+V1) when judging that V2 is larger than V1 or a vector (V0+V1+V2) supplied from an adder 7 as an optimum motion vector when judging that V2 is smaller than V1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion vector detecting circuit, and can be applied to a high-efficiency coding apparatus for television signals, a television signal system converting apparatus, and the like.

[0002]

2. Description of the Related Art In recent years, there has been a demand for improvement in motion vector detection for detecting the direction of movement of a moving body, the magnitude of movement, etc. in a digitized television signal.

This motion vector indicates the magnitude and direction of the motion of the moving object within the screen. This motion vector detection technique is used for interframe coding in high-efficiency coding of television signals, field interpolation in converting the number of fields in television system conversion, and the like.

As a motion vector detecting method, for example,
There are gradient method and iterative gradient method. The gradient method is a method for obtaining motion from the relationship between the spatial gradient of images and the difference between images. This method is disclosed, for example, in Japanese Patent Laid-Open No. 60-158786.

Further, in the iterative gradient method, a method for obtaining and detecting an initial deviation vector in order to further improve the detection accuracy of a motion vector is disclosed in Japanese Patent Laid-Open No. 62-20698.
No. 0, JP-A-4-78286, and the like.

The initial displacement vector is obtained by subdividing a television signal of one field or one frame into block units each consisting of m × n pixels in the horizontal direction and n lines in the vertical direction. It is assumed that the motion vector of is used.

Here, a method for obtaining a true motion vector using the initial displacement vector will be described with reference to FIGS. 2 and 3.

FIG. 2 is a diagram showing the correspondence between the blocks of the current field and the previous field. Further, FIG. 3 is an explanatory diagram of motion vectors. In FIG. 2, the optimum motion vector is selected from the motion vectors detected in time before for the detected block (m1, n1) for which the true motion vector is to be obtained, and this selection is performed. The obtained motion vector is set as the initial displacement vector V0.

Initial displacement vector V0 = (α0, β0) Then, in FIG. 3, the motion is performed based on the block (m1 + α0, n1 + β0) whose coordinates are displaced by the initial displacement vector and the detected block. First deviations V1 and 2
The second deviation V2 and V2 are calculated using the iterative gradient method.

Deflection amount for the first movement V1 = (α1, β1) Deflection amount for the second movement V2 = (α2, β2) Further, the initial deviation vector V0 and the movement vector deviations V1 and V2 By adding and, the true motion vector V for the detected block can be obtained.

True motion vector V = V0 + V1 + V2 In addition to the iterative gradient method, a pattern matching method may be used in the method of detecting the motion displacement vector. Further, the number of iterations of the iterative gradient method may be two or more.

[0012]

However, the deviations (V1, V2) are obtained by using the conventional iterative gradient method as described above, and the deviations (V1, V2) are added to the above-mentioned initial deviation vector V0 and added to the detected block. When the motion vector V = V0 + V1 + V2 is calculated, when the deviation V1 or the deviation V2 is calculated, if one of the deviations is erroneously detected, an inappropriate motion vector is detected. .

If such an inappropriate motion vector is detected, there is a problem that the image is distorted when used for image reproduction.

Therefore, a motion vector detection circuit with high detection accuracy is required due to such problems.

In particular, when the displacement vector is calculated by an arithmetic expression as in the above-mentioned iterative gradient method, there is a problem that the possibility of false detection increases depending on the image.

The present invention has been made in view of the above problems, and an object thereof is to provide a motion vector detection circuit capable of improving the motion vector detection accuracy with a simple configuration. .

[0017]

In order to achieve the above-mentioned object, the present invention divides an image signal into a plurality of blocks, and each divided block is separated by at least one field or more or one frame or more. According to the gradient method, an initial displacement vector detecting means for detecting an initial displacement vector (for example, V0) of the motion between each block of the image signal,
From the first displacement vector detecting means for obtaining each displacement vector from the respective blocks of the image signal separated by at least one field or more or one frame or more to the Nth (integer of 2 or more) displacement vector detecting means Equipped, above first
The th displacement vector detecting means detects the first displacement vector (from the initial displacement vector (for example, V0) of the motion and the signal between the blocks of the image signal separated by at least one field or one frame or more ( For example, V1) is detected, and the J (2-N) th deviation vector detection means is
It is obtained from the signal between the blocks of the image signal separated by at least one field or more or one frame and the (J-1) th deviation vector detected by the (J-1) th deviation vector detecting means. The J-th deviation vector (for example, V2) is detected from the (J-1) -th motion vector (for example, V0 + V1), and the J-th deviation vector (for example, V2) is detected from the J-th deviation vector (for example, V2). A motion vector detection circuit for detecting a motion vector (for example, V0 + V1 + V2) is realized by including the following characteristic means.

That is, the magnitude relationship between the (J-1) th deviation vector (for example, V1) and the Jth deviation vector (for example, V2) is compared, and the (J-1) th deviation vector is compared. When the J-th deviation vector (for example, V2) is smaller than the deviation vector (for example, V1), the above J-th deviation vector
When the th motion vector (for example, V0 + V1 + V2) is output as the optimum motion vector, and the above Jth displacement vector (for example, V2) is larger than the above (J−1) th displacement vector (for example, V1). Is the above (J-
It is characterized in that it comprises a motion vector evaluation means for outputting the 1) th motion vector (for example, V0 + V1) as an optimum motion vector.

[0019]

According to the motion vector detection circuit of the present invention, the motion vector evaluation means includes the (J-1) th deviation vector (for example, V1) and the Jth deviation vector (for example, V1) detected by the gradient method. , V2) and the J-th deviation vector (for example, V2) is smaller than the (J−1) th deviation vector (for example, V1), the motion using the iterative gradient method is performed. The J-th motion vector (for example, V0 + V1 + V2) can be output as the optimum motion vector because of the convergence of the vector.

However, when the J-th deviation vector (for example, V2) is larger than the (J-1) -th deviation vector (for example, V1), the J-th deviation vector (for example, V2) is set. Since it is regarded as an erroneous detection and the (J-1) th motion vector (for example, V0 + V1) is output as the optimum motion vector, a highly accurate motion vector that is not affected by an erroneous displacement vector compared to the conventional output is output. can do.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a motion vector detecting circuit according to the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 is a functional block diagram of a motion vector detection circuit according to the first embodiment.

In the functional block diagram of FIG. 1, the motion vector detection circuit is the initial displacement vector selection circuit 1.
And a first gradient method computing circuit 2 and a second gradient method computing circuit 3
And a comparison circuit 4, an evaluation circuit 5, and adders 6 and 7.

The motion vector detecting circuit has
The current field signal A and the previous field B are supplied,
These signals are transmitted to the initial displacement vector selection circuit 1 and the first displacement vector selection circuit 1.
It is supplied to the gradient method computing circuit 2 and the second gradient method computing circuit 3.

The initial displacement vector selection circuit 1 is
The initial gradient vector V0 is obtained and the first gradient method arithmetic circuit 2
To the adder 6. Then, the first gradient method operation circuit 2 performs the first gradient method operation from the supplied initial deviation vector V0 and the current field signal A and the previous field signal B to obtain the deviation amount V1 and adder 6 and the comparison circuit 4.

Then, the adder 6 adds the deviation amount V1 and the initial deviation vector V0 to obtain a motion vector (V0 + V
1) is supplied to the second gradient method operation circuit 3, the adder 7, and the evaluation circuit 5. Then, the second gradient method arithmetic circuit 3 supplies the supplied motion vector (V0 + V1) and the current field signal A
Then, the second gradient method calculation is performed from the previous field signal B to obtain the deviation V2, and the deviation V2 is supplied to the adder 7 and the comparison circuit 4.

Then, the adder 7 adds the deviation amount V2 and the motion vector (V0 + V1) to obtain the motion vector (V0
+ V1 + V2) is supplied to the evaluation circuit 5. Then, the comparison circuit 4 compares the value of the deviation amount V1 from the first gradient method calculation circuit 2 with the value of the deviation amount V2 from the second gradient method calculation circuit 3. If the relationship between the value of the deviation amount V1 and the value of the deviation amount V2 is the relationship of the deviation amount V1 <the deviation amount V2, the second
Since it is considered that the calculation result in the gradient method calculation circuit 3 includes the erroneous detection of the deviation, the evaluation circuit 5 is caused to select the motion vector (V0 + V1) and the optimum motion vector V = (V0 + V1). As a result, the output control is performed on the evaluation circuit 5.

That is, if a motion vector capable of normally minimizing the error is detected, the deviation amount between the same fields obtained from (V0 + V1) is obtained rather than the deviation amount V1 obtained from the initial deviation vector V0. Since V2 does not become large, when the deviation V2 becomes larger, the deviation V2 is invalidated because there is an error in the detection due to some cause.

Further, in the comparison circuit 4, when the relationship between the value of the deviation V1 and the value of the deviation V2 is other than the relationship of V1 <V2, that is, the deviation V1 ≧ the deviation V2. Therefore, the comparison circuit 4 does not determine that the motion vector (V0 + V1
+ V2) is selected, and the optimum motion vector V = (V0
+ V1 + V2) is output to the evaluation circuit 5.

FIG. 4 is an explanatory diagram for obtaining the initial displacement vector V0 in the initial displacement vector selection circuit 1.

In FIG. 4, six types of candidate vectors are selected as initial candidate vectors. That is, the initial displacement vector is obtained from the following motion vectors V _A , V _B , V _C , and V _N , the average motion vector V _E, and the acceleration (displacement) vector Vg.

Here, the motion vector V _A is a motion vector detected in a block immediately above the same field with respect to the detected block in the current field. The motion vector V _B is the motion vector detected in the upper right block of the same field. The motion vector V _C is also a motion vector detected in the block on the left side of the same field. still,
It may be used a vector V _{C *} next vector V _C in the same field instead of the vector V _C.

The motion vector V _N is a motion vector corresponding to the block immediately below the detected block 41 detected in the previous field. The average motion vector V _E is the average of the motion vectors of the block at the same position as the detected block one field before and the surrounding blocks, and this motion vector V _E = (V _G + V _H + V _I +
It is an average motion vector obtained by V _J + V _K + V _L + V _M + V _N + V _Q ) / 9. The acceleration (deviation) vector Vg is a deviation vector obtained by Vg = 2 · V _E −Vp. Incidentally, the average vector Vp is the average vector of the field before two.

A field signal in which the coordinates of the block are displaced by the values of these six types of initial displacement candidate vectors, and 1
The absolute value of the difference signal between the field signal or the field signal separated by one frame is accumulated for the number of pixels in the block, and the one having the smallest accumulated value is selected from the initial deviation candidate vectors, and this is optimized. Output as the initial displacement vector V0.

Next, an example of the calculation method of the first gradient method calculation circuit 2 and the second gradient method calculation circuit 3 will be shown.

For example, the displacement vector is obtained from the detected block in the current field and the block in which the coordinates of the initial displacement vector in the previous field are displaced by the following four equations.

Vx = Σ (SIGN · ΔX · DFD) / Σ | ΔX | ...
(1) Vy = Σ (SIGN · ΔY · DFD) / Σ | ΔY | ...
(2) Here, the above ΔX and ΔY are obtained by the following equation. ΔX = (A _{n + 1, m} − A _{n−1, m} ) / 2 ...
(3) ΔY = (A _{n, m + 1} −A _{n, m−1} ) / 2 ...
(4) Here, A _{n, m} represents the pixel signal value of the coordinates of the n-th pixel and the m-th line. Further, SIGN represents a sign (+1 or -1) of ΔX or ΔY. Furthermore, DF
D is the difference value of each pixel between the current field and the previous field.

By the above (1) and (2), the displacement vector V1 = (Vx1, Vy1) and the displacement vector V2 =
(Vx2, Vy2) can be obtained.

According to the motion vector detection circuit of the first embodiment described above, the evaluation circuit 5 determines whether (V0 + V1 + V2) or (V0) depending on the magnitude relationship between the values of the deviation V1 and the deviation V2.
Since 0 + V1) can be output as a motion vector, erroneous detection of a motion vector can be reduced.
Moreover, it can be realized with a simple configuration. Therefore,
By adopting this motion vector, it is possible to reduce image distortion during image reproduction.

Therefore, it is effective when applied as a motion vector detecting circuit for a high-efficiency coding apparatus for television signals, a television system converting apparatus, and the like.

Second Embodiment FIG. 5 is a functional block diagram of a motion vector detecting circuit of the second embodiment.

In FIG. 5, the motion vector detection circuit is different from that of FIG. 1 in that the evaluation circuit and the adder 7 of FIG. 1 are replaced with an AND gate 9 and an adder 8. Is.

In FIG. 5 of the second embodiment, the same reference numerals as those in FIG. 1 of the first embodiment represent the same functions. Therefore, the initial deviation vector selection circuit 1, the first gradient method computing circuit 2, and the second gradient method computing circuit 3
It is assumed that the above configuration method can also be realized by the configuration of the first embodiment.

Then, the second gradient method operation circuit 3 supplies the obtained deviation V2 to the AND gate 9 and the comparator 4.
Then, the comparator 4 operates in the same manner as in the first embodiment so that the deviation V1
If the relationship between the deviation V2 and V1 <V2,
The logic 0 is output and supplied to the AND gate 9. Then, the AND gate 9 controls and outputs the supplied deviation V2 by the logic signal supplied from the comparator 4. That is, the AND gate 9 outputs the logic 1 (V1 <V1 <
(In the case of a relationship other than V2), the deviation V2 is gated out and supplied to the adder 8.

Further, the AND gate 9 does not output the excursion V2 when the logic 0 (when V1 <V2 is satisfied) is supplied from the comparator 4.

Then, the adder 8 adds the signal from the AND gate 9 and the motion vector (V0 + V1) and outputs the motion vector V. That is, in the case of the relation of the deviation V1 <the deviation V2, the deviation V from the AND gate 9
Since 2 is not supplied, the adder 8 outputs (V0 + V1) as a motion vector.

Further, the adder 8 has a deviation V1 <a deviation V
In the case other than the relationship of 2, the deviation V2 from the AND gate 9
Is supplied, it is possible to perform addition with the motion vector (V0 + V1) supplied from the adder 6 and output (V0 + V1 + V2) as the motion vector.

According to the motion vector detection circuit of the second embodiment, as in the first embodiment, (V0 + V1 + V2) or (V0 + V1) can be calculated according to the magnitude relationship between the values of the deviation V1 and the deviation V2. Since it can be output as a motion vector, erroneous detection of the motion vector can be reduced. Moreover, it can be realized with a simple configuration. Therefore, by adopting this motion vector, it is possible to reduce image distortion during image reproduction.

Furthermore, it is effective when applied as a motion vector detecting circuit for a high-efficiency encoder for television signals, a television system converter, and the like.

[0050] Other embodiments In the first and second embodiments described above, by two gradient calculation circuit, but was determined deviation amount V1, V2, it is limited to the two Absent. Even a large number of iterative gradient method operations can be applied by slightly changing the configuration.

Also, regarding the gradient method calculation method, it has been described above that it is obtained by the equations (1) to (4), but the invention is not limited to this. Further, this calculation can be realized by either program processing or hardware processing.

Further, regarding the method of obtaining the initial displacement vector V0 in the initial displacement vector selection circuit 1, the method of obtaining from the six types of candidate vectors has been described above with reference to FIG.
It is not limited to this. Other configurations may be used.

Furthermore, in the above embodiment, the present field signal and the previous field signal are used for explanation, but it is also possible to use image signals separated by one field or more, or image signals separated by one frame or more. May be between.

[0054]

As described above, according to the motion vector detection circuit of the present invention, since the motion vector evaluation means is provided, it is possible to easily obtain an accurate optimum motion vector which is not affected by an erroneous displacement vector. It can be detected with various configurations.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a motion vector detection circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram showing correspondence between current field blocks and previous field blocks in a conventional example.

FIG. 3 is an explanatory diagram of a motion vector of a conventional example.

FIG. 4 is an explanatory diagram of initial deviation candidate vectors of the first embodiment and the second embodiment.

FIG. 5 is a functional block diagram of a motion vector detection circuit according to a second embodiment.

[Explanation of symbols]

1 ... Initial deviation vector selection circuit, 2 ... 1st gradient method arithmetic circuit, 3 ... 2nd gradient method arithmetic circuit, 4 ... Comparison circuit, 5 ... Evaluation circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Nojiri 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside the Japan Broadcasting Corporation Broadcasting Technology Laboratory (72) Inventor Hiroshi Hirabayashi 1-10-11 Kinuta, Setagaya-ku, Tokyo No. Japan Broadcasting Corporation Broadcasting Technology Research Laboratory (72) Inventor Sonehara Gen 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside Japan Broadcasting Corporation Broadcasting Technology Research Laboratory

Claims (1)

[Claims] 1. An initial stage of dividing an image signal into a plurality of blocks, and detecting an initial displacement vector of motion between the blocks of the image signal separated by at least one field or one frame for each divided block. The displacement vector detecting means and the first displacement vector detecting means for obtaining each displacement vector between the respective blocks of the image signal separated by at least one field or one frame according to the gradient method from the Nth (2 or more) (Integer) up to the second displacement vector detecting means, wherein the first displacement vector detecting means is provided between the initial displacement vector of the motion and each of the blocks of the image signal separated by at least one field or one frame or more. And the J (2 to N) th displacement vector detecting means detects at least one field. The (J-1) th deviation vector detected by the signal between the respective blocks of the image signal separated by the above or one frame or more and the (J-1) th deviation vector detected by the (J-1) th deviation vector detecting means. A J-1) th motion vector and a J-th deviation vector are detected from the J-th deviation vector, and a J-th deviation vector is detected from the J-th deviation vector. The magnitude relationship between the th deviation vector and the Jth deviation vector is compared, and if the Jth deviation vector is smaller than the (J-1) th deviation vector, the Jth deviation vector is compared. The motion vector is output as the optimum motion vector, and when the J-th deviation vector is larger than the (J-1) -th deviation vector, the (J-1) -th motion vector is set as the optimum motion vector. Output as A motion vector detection circuit characterized by comprising motion vector evaluation means.