JP2008011476A - Frame interpolation apparatus and frame interpolation method - Google Patents

Abstract

A frame interpolating apparatus and a frame interpolating method capable of coping with a large motion vector without requiring a large search range and performing appropriate frame interpolation.
A first motion vector calculating unit 11a calculates a first motion vector in order to create a first interpolation frame from first and second frames P1, P2. In order to create a second interpolation frame from the second and third frames P2 and P3, the second motion vector calculation unit 11a searches for the arrival point of the first motion vector when calculating the second motion vector. The second motion vector is calculated by setting the range.
[Selection] Figure 1

Description

  The present invention relates to a frame interpolation apparatus and a frame interpolation method applied when displaying a moving image.

In an apparatus for displaying a moving image such as a liquid crystal television receiver, a frame interpolation apparatus for generating an interpolated frame image may be provided for the purpose of improving display characteristics. This frame interpolation device generates an interpolated frame image by obtaining motion vectors of, for example, a current frame image and a past frame image around and around the time point.
In order to generate an interpolated frame image in this manner, it is necessary to obtain a motion vector, and a unit block such as a macro block is employed when obtaining a motion vector. Then, a search range is determined as a range in which the position of the unit block is searched. For example, Patent Document 1 discloses a method of detecting a motion vector from a search range determined by the average speed and direction of a motion vector in an already detected area as described below.

In this method, when a motion vector is detected in a unit block, the motion vector having the smallest prediction error component among the motion vectors already detected in the block adjacent to the target block is set as the representative vector of the target block. When the predetermined value is exceeded, the search range defined by the average speed calculated from the motion vector already detected in the predetermined area and its direction is searched by the block matching process, and the motion vector of the target block is detected.
In general, if the search range is set to a large range with the unit block as the center position, a motion vector can be obtained even with a large motion (fast motion).
JP 2000-201328 A JP 2004-357215 A

However, if the search range is increased, the amount of block matching processing increases significantly. Therefore, it is necessary to increase the scale of hardware, which increases costs, and it is difficult to set a large search range. become.
In addition, in the method of Patent Document 1, when there is a region where the movement speed and the surrounding movement are different in one frame, a search in which the motion vector is set based on the average speed of the surrounding motion vectors already detected. May deviate from scope. Therefore, if the search range is not enlarged, there is a possibility that the motion vector cannot be calculated.
The present invention has been made in view of the above points, and provides a frame interpolation apparatus and a frame interpolation method that can cope with a large motion vector without requiring a large search range and can perform appropriate frame interpolation. For the purpose.

The frame interpolating device according to an aspect of the present invention provides the first and second frame images for each predetermined block in the first interpolated frame image that interpolates between the first and second frame images moving back and forth in time. Calculating a relative amount of motion between the first and second image blocks corresponding to each predetermined block in the first search range, so that each of the predetermined blocks is relative to the first image block. First motion vector calculating means for calculating a first motion vector representing a correct amount of motion;
For each predetermined block in the second interpolated frame image that interpolates between the second and third frame images moving back and forth in time, the second and second corresponding to each predetermined block in the second and third frame images By calculating the relative motion amount between the three image blocks within the second search range, a second motion vector representing the relative motion amount of each predetermined block with respect to the second image block is calculated. If you want to
The position of the first motion vector calculated for each predetermined block is set to the center position of the second search range set on the third frame image to calculate the second motion vector. Second motion vector calculating means for
It is characterized by comprising.

The frame interpolation method according to an aspect of the present invention provides the first and second frame images for each predetermined block in the first interpolated frame image that interpolates between the first and second frame images that move back and forth in time. Calculating a relative amount of motion between the first and second image blocks corresponding to each predetermined block in the first search range, so that each of the predetermined blocks is relative to the first image block. A first motion vector calculating step for calculating a first motion vector representing a correct amount of motion;
For each predetermined block in the second interpolated frame image that interpolates between the second and third frame images moving back and forth in time, the second and second corresponding to each predetermined block in the second and third frame images By calculating the relative motion amount between the three image blocks within the second search range, a second motion vector representing the relative motion amount of each predetermined block with respect to the second image block is calculated. If you want to
The position of the first motion vector calculated for each predetermined block is set to the center position of the second search range set on the third frame image to calculate the second motion vector. A second motion vector calculating step,
It is characterized by comprising.

  According to the present invention, a large search range can be handled without requiring a large search range, and appropriate frame interpolation can be performed.

Embodiments of the present invention will be described below with reference to the drawings.
(One embodiment)
FIG. 1 shows a moving image display apparatus 1 having a frame interpolation apparatus according to an embodiment of the present invention. The moving image display device 1 includes an image generation unit 2 that generates a frame image of a moving image (abbreviated simply as a frame), a frame interpolation device 3 that generates an interpolated frame image (abbreviated as an interpolated frame) from two adjacent frames, And an image display unit 4 such as a liquid crystal display for displaying frames and interpolation frames.
The image generation unit 2 is configured by, for example, a video camera that generates a moving image. In addition to the television camera, a television tuner and a video demodulation circuit may be provided. In addition, in an existing television receiver, it is possible to add a frame interpolation device 3 to improve the display characteristics of moving images.
The frame interpolation device 3 generates, for example, a double-speed frame by generating an interpolation frame for a frame having a predetermined frame rate generated by the image generation unit 2. The image display unit 4 to which the double-speed frame is input displays a moving image at double speed and improves the moving image display characteristics as compared with the case where the frame interpolation device 3 is not used.

FIG. 2 shows a configuration of the frame interpolation device 3 according to an embodiment of the present invention.
The frame interpolating device 3 uses a frame memory 6 for temporarily storing a plurality of input frames, and two frames stored in the frame memory 6 that move back and forth in time. The first and second interpolation frame generation units 7a and 7b generate two interpolation frames.
The frame memory 6 includes first, second, and third frame memories 6a, 6b, and 6c that respectively store first, second, and third frames P1, P2, and P3 that are sequentially input in time.

  In addition, the first interpolation frame generation unit 7a calculates a first motion vector that calculates a first motion vector representing a motion amount between blocks having a predetermined number of pixels from the first and second frames P1 and P2. Unit 11a, a first motion vector storage unit 12a for storing information on the calculated first motion vector, and a first search range setting for setting a first search range for calculating the first motion vector Part 13a.

In addition, the second interpolation frame generation unit 7b calculates a second motion vector that calculates a second motion vector representing a motion amount between blocks having a predetermined number of pixels from the second and third frames P2 and P3. Unit 11b, a second motion vector storage unit 12b for storing information of the calculated second motion vector, and a second search range setting for setting a second search range for calculating the second motion vector Part 13ba. Note that the first search range and the second search range are set to the same number of pixels.
The first, second, and third frames P1, P2, and P3 stored in the frame memory 6 and the first and second interpolation frames generated by the first and second interpolation frame generation units 7a and 7b, respectively. Q1 and Q2 are output to the image display unit 4 in the order of P1, Q1, P2, Q2, and P3 as shown in FIG. Then, the image display unit 4 displays these frames P1, Q1, P2, Q2, and P3 as double-speed images.
The first and second interpolation frame generation units 7a and 7b generate an interpolation frame using a symmetric serch method as described below. The symmetric serch method is disclosed in Patent Document 2.

In this case, when the first interpolation frame, that is, the first interpolation frame Q1, is generated, since there is no past motion vector that can be referred to, the motion vector is calculated by a normal method.
On the other hand, when the second interpolation frame Q2 is generated, the first motion vector is obtained by using the information of the first motion vector obtained at the time of generating the first interpolation frame Q1. Is set to the center position of the second search range, and the second motion vector is calculated by the block matching method.
Therefore, as shown in FIG. 2, the second search range setting unit 13b reads the information on the first motion vector stored in the first motion vector storage unit 12a, and reaches the first motion vector. The second search range is set so that the position becomes the center position.
As described above, the first and second interpolation frame generation units 7a and 7b differ only in whether or not the previous motion vector information is used when generating the interpolation frame using the symmetric serch method. .

Therefore, in FIG. 2, the first and second interpolation frame generation units 7a and 7b are shown as different block configurations, but it is clear that one block can perform both functions. (It will be described as one in the description of FIG. 7 described later).
FIG. 4 shows an explanatory diagram in which the first interpolation frame Q1 is generated from the first and second frames P1 and P2 by the first interpolation frame generation unit 7a.
As shown in FIG. 4, the interpolation frame plane Q prepared for generating the first interpolation frame Q1 is divided (divided) into blocks having a predetermined number of pixels in the horizontal and vertical directions (hereinafter referred to as interpolation target blocks) Bi. ) Here, Bi represents one interpolation target block from B1 to Bn in FIG.
In FIG. 4, the horizontal direction indicates time, and the vertical direction indicates the two-dimensional position of the image. The interpolated frame plane Q is arranged at an intermediate position between the first and second frames P1 and P2 facing each other on the adjacent time.
Then, the first interpolation frame generation unit 7a scans the divided interpolation target blocks Bi, for example, two-dimensionally sequentially from B1, and performs motion estimation processing, in other words, motion vector calculation processing, for each interpolation target block Bi. .

As shown in FIG. 4, when the motion vector calculation process is performed on the interpolation target block Bi, the first interpolation frame generation unit 7a is arranged so as to be geometrically symmetrical with respect to the position of the interpolation target block Bi. Sets the first search ranges Ra and Rb on the first and second frames P1 and P2, respectively.
In addition, a pair of image blocks Ba ′ and Bb ′ having the same pixel size as the interpolation target block Bi is set in the first search ranges Ra and Rb, and the first interpolation frame generation unit 7a sets the first search range Ra. , Rb is searched to search for image blocks Ba and Bb having the maximum degree of correlation in the pair of image blocks Ba ′ and Bb ′ (described later in FIG. 5).

Then, the first motion vector calculation unit 11a calculates a motion vector between the pair of image blocks Ba and Bb, obtains ½ of the motion vector, and calculates the first interpolation target block Bi for the image block Ba. Motion vector Vi is calculated.
In the present embodiment, since the first interpolation frame Q1 that is a temporally intermediate position between the first and second frames P1 and P2 is generated, the first motion vector calculation unit 11a 1/2 of the motion vector between the pair of blocks Ba and Bb is calculated as the first motion vector Vi of the interpolation target block Bi for the image block Ba.
The first motion vector Vi is stored in the first motion vector storage unit 12a.

In addition, the motion of the image of the interpolation target block Bi is estimated that the image of the image block Ba has moved (moved) by this first motion vector Vi. Then, the image of the interpolation target block Bi is generated using the image of the image block Ba. Of course, the image of the interpolation target block Bi may be generated using both the images of both the image blocks Ba and Bb.
As described above, when the first motion vector from the first interpolation target block B1 to the last interpolation target block Bn in the first search ranges Ra and Rb is calculated as shown in FIG. The interpolation frame generation unit 7a generates the first interpolation frame Q1 based on the position information of the first motion vector Vi calculated for the interpolation target block Bi and the corresponding image block Ba.
FIG. 5 is an explanatory diagram of processing for searching the image blocks Ba and Bb having the highest degree of correlation between the image blocks Ba ′ and Bb ′ by searching the first search ranges Ra and Rb.

As shown in FIG. 5, with respect to the interpolation target block Bi, image blocks Ba ′ and Bb ′ that are geometrically symmetrical to each other are set in the first search areas Ra and Rb, respectively, and the image block Ba ′. , Bb ′ is shifted in the horizontal and vertical directions so as to maintain symmetry, and an integrated value (SAD) of the difference between pixels at geometrically symmetrical positions in each image block Ba ′ and Bb ′ is calculated. .
In FIG. 5, the image block Ba ′, Bb ′ pair is first set at the position indicated by the solid line, and the integrated value Σ1 of the difference between the corresponding pixels in the image block Ba ′, Bb ′ pair is calculated at this set position. To do.
Next, the image block Ba ′, Bb ′ pair is shifted by one pixel (indicated by a dotted line), for example, in the horizontal direction (so as to maintain symmetry), and similarly, an integrated value Σ2 of the difference is calculated. Such processing is repeated until the last image block position.

Then, among the integrated values of all the differences calculated in the first search ranges Ra and Rb, the one having the smallest absolute value of the difference integrated value or the one having the highest degree of correlation is designated as the image blocks Ba and Bb. (And the first motion vector Vi is calculated at that time).
In FIG. 5, for example, the shaded lines indicate the image blocks Ba and Bb having the highest correlation.
In this way, the first interpolation frame is generated using the symmetric serch method.
The second interpolation frame generation unit 7b also generates a second interpolation frame Q2 by using a substantially similar symmetric serch method.
In this case, the process described in FIG. 4 uses the second and third frames P2 and P3 instead of the first and second frames P1 and P2. The second search ranges Rb and Rc and the image blocks Bb ′ and Bc ′ are set in the second and third frames P2 and P3.

  In addition, since the first interpolation frame Q1, which is the first interpolation frame, does not have information on the previous motion vector, the first search ranges Ra and Rb are, for example, preset default values (for example, motion vectors). Is set as the position of the first search range Ra, Rb).

On the other hand, the second search range setting unit 13b reads out the first motion vector Vi stored in the first motion vector storage unit 12a, and uses the arrival point of the first motion vector Vi as a central position. The positions of the second search ranges Rb and Rc are set.
For example, if the motion vector Vi of the interpolation target block Bi is calculated by the processing described with reference to FIG. 5, the second search range setting unit 13b uses the motion vector Vi as shown in FIG. Rb and Rc are set.

As shown by the solid line in FIG. 6, the second search range Rc (set during the third frame P3) has a center position whose block is to be interpolated in the previous interpolation frame (that is, the first interpolation frame Q1). The reaching position of the motion vector Vi calculated for Bi is set.
With this setting, the center position of Rb set at a position symmetrical to the second search range Rc is set to the arrival position of -Vi obtained by inverting the motion vector Vi.
In FIG. 6, the two-dot chain line indicates the second search ranges Rb ′ and Rc ′ when the movement vector Vi is set without moving, for reference.
In this way, the second search ranges Rb and Rc are set, and the second interpolation frame generation unit 7b also uses the substantially similar symmetric serch method to generate the second interpolation frame Q2.
For the third interpolation frame following the second interpolation frame Q2, the third search range may be set using the motion vector obtained when the second interpolation frame Q2 is generated. . In other words, the motion vector obtained when the second interpolation frame Q2 is generated in the same manner as the second interpolation frame is generated using the motion vector obtained at the time of the first interpolation frame Q1. The third search range may be set using

FIG. 7 shows the second motion for calculating the second interpolation frame Q2 (including calculation after the third frame Q3) from the calculation of the first motion vector for calculating the first interpolation frame Q1. The flowchart which generalized the process sequence which calculates a vector is shown.
In the following description, the first and second interpolation frame generation units 7a and 7b shown in FIG. 2 will be described as one interpolation frame generation unit 7 by omitting a and b (reference numerals 11a, 11b, 12a and 12b). And so on).
In the first step S1, the interpolation frame generation unit 7 sets a parameter k corresponding to the kth interpolation frame Qk to an initial value 1. In the next step S2, the frame memory 6 stores the kth and k + 1th frames Pk and Pk + 1 (in this case, P1, P2 since k = 1) in time order.

In the next step S3, the interpolation frame generation unit 7 divides the interpolation frame plane Q for generating the kth interpolation frame Qk into a plurality (i = 1 to n) of interpolation target blocks Bi. Then, as shown in step S4, a parameter i indicating the block position of the interpolation target block Bi is set to an initial value 1.
In the next step S5, the interpolation frame generator 7 determines whether k = 1. When this condition is satisfied, as shown in step S6, the search range setting unit 13 sets the search range corresponding to the interpolation target block Bi to a predetermined position and sets the kth search ranges Rki, Rk + 1i (in FIG. 4). Equivalent to Ra and Rb).
In this case, the kth search ranges Rki and Rk + 1i are set at geometrically symmetrical positions with respect to the interpolation target block Bi.
Then, the interpolation frame generation unit 7 cuts out images of the kth search ranges Rki and Rk + 1i from the kth and k + 1th frames Pk and Pk + 1, respectively.

On the other hand, if k is not 1, the center position of the kth search ranges Rki, Rk + 1i is set to the arrival position of the motion vector Vi obtained in the previous interpolation frame generation as shown in step S7.
In this case, the kth search ranges Rki and Rk + 1i are set at geometrically symmetrical positions with respect to the interpolation target block Bi.
Then, images of the kth search ranges Rki and Rk + 1i are cut out from the kth and k + 1th frames Pk and Pk + 1, respectively.
After step S6 or step S7, the process proceeds to step S8.
In this step S8, image blocks Bkj ′ and Bk + 1j ′ (Ba ′ and Bb in FIG. 4) are respectively applied to the image portions of the k-th search ranges Rki and Rk + 1i so as to be geometrically symmetrical with respect to the interpolation target block Bi. (Equivalent to ').

Here, j is a parameter indicating the position of the image blocks Bkj ′ and Bk + 1j ′ set in the images of the k-th search ranges Rki and Rk + 1i, for example, j = 1 to m.
Then, the parameter j is set to the initial value 1 as shown in step S9.
Then, the image block Bkj ′, Bk + 1j ′ pair is moved (scanned) by the symmmtri serch method within the k-th search range Rki, Rk + 1i as follows, and the image block Bkj ′, Bk + 1j ′ pair having the highest correlation is obtained. Performed by block matching process.
In the next step S10, the integrated value of the difference is calculated between each pixel in the image block Bkj ′, Bk + 1j ′ pair that is geometrically symmetrical to each other.
In the next step S11, it is determined whether j = m. If this condition is not satisfied, j = j + 1 is performed in step S12, and the process returns to step S10. That is, the process of step S10 is repeated while moving the image block Bkj ′, Bk + 1j ′ pair by one pixel in the horizontal direction and the vertical direction.

On the other hand, if the condition of j = m is satisfied in step S11, the process of step S10 has been completed up to the last position of the kth search ranges Rki, Rk + 1i, so the process proceeds to the next step S13.
In this step S13, a pair of image blocks Bk (i) and Bk + 1 (i) (corresponding to Ba and Bb in FIG. 4) having the maximum degree of correlation (here, the absolute value of the difference integrated value is minimum). calculate. Here, (i) indicates that it depends on i.
Then, as shown in step S14, from the position between the image block Bk (i) and Bk + 1 (i) pair of the integrated value of the difference that maximizes the correlation, between the image block Bk (i) and Bk + 1 (i) pair. A motion vector is calculated.
Then, ½ of the motion vector is calculated as the motion vector Vi of the interpolation target block Bi. Here, it is simply expressed as Vi, but it may be expressed as Vi (k) to indicate that it is calculated when the kth interpolation frame Qk is generated.

The motion vector Vi is stored in the (kth) motion vector storage unit 12.
In the next step S15, it is determined whether i = n. If the condition of i = n is not satisfied, the process of i = i + 1 is performed in step S16, and the process returns to step S5.
On the other hand, when the condition of i = n is satisfied, the calculation of the motion vector Vi for all the interpolation target blocks Bi in the frame plane Q is completed, so k = k + 1 is performed as shown in step S17. Then, the process returns to step S2.
Then, the motion vector Vi of the next interpolation frame Qk is calculated. In this case, since the motion vector Vi is calculated in the previous interpolation frame Qk-1, the process of step S7 is performed after step S5.

According to the frame interpolation device 3 according to the present embodiment that performs the processing as described above, the next motion vector is calculated by moving the center of the search range by the motion vector calculated at the time of generating the previous interpolation frame in terms of time. Thus, even when the amount of motion is large, the motion vector can be calculated appropriately without increasing the search range. Accordingly, the hardware of the frame interpolation device 3 can be dealt with with a small scale, and the cost of the frame interpolation device 3 can be reduced.
FIG. 8 is an explanatory diagram of the operation according to the present embodiment. FIG. 8 schematically shows an example in which a certain area in a moving image moves over time on the first, second, and third frames as A, B, and C, for example.

In this case, when the first interpolation frame Q1 between A and B is generated, the motion vector Vi (k = 1) of a certain interpolation target block Bi (k = 1) Calculated as half.
Then, corresponding to the interpolation target block Bi (k = 1) of the interpolation frame Q1, the second search range Rc in the interpolation target block Bi (k = 2) of the interpolation frame Q2 that interpolates between B and C is set. When setting, the position moved by the arrival position of the motion vector Vi (k = 1) is set as the center position of the second search range Rc.
By setting the second search range Rc in this way, when the motion vector Vi (k = 1) is not moved in this way, the movement of the region C cannot be detected unless the large search range is set. The movement can be captured within the second search range Rc.

Therefore, according to the present embodiment, the motion vector in the image is accurately obtained even in the case of an image having a large motion or a motion that accelerates without changing the size (region) of the search range. be able to. Therefore, a high-quality interpolation frame can be generated, and display characteristics can be improved.
In other words, in this embodiment, since motion vector information having a large correlation between temporally adjacent frames such as a moving image is used effectively, an interpolation frame for interpolating them is generated. Even if the search range is not enlarged, it is possible to effectively interpolate between frames with large changes.
In the above description, the case where the motion vector information in the previous interpolation frame Qk-1 is used when calculating the motion vector in a certain interpolation frame Qk has been described. Information on motion vectors may also be used.

For example, when the motion vector Vk-1 of the next previous interpolation frame Qk-1 is changed from the motion vector (represented by Vk-2) of the previous interpolation frame Qk-2, these motion vectors Vk. The center position Rcen of the search range when searching for the motion vector Vk of the next interpolation frame Qk may be set in consideration of changes in −2 and Vk−1.
In this case, the center position Rcen of the search range may be set as follows.

Rcen = Vk-1 + α (Vk-1-Vk-2) (1)
Here, the coefficient α is a value from 0 to 1. When setting is made as in Equation 1, when the motion vectors Vk-2 to Vk-1 are further accelerated or decelerated, the center position Rcen of the search range is set in consideration of the degree of acceleration or deceleration.

The general feature will be described. For example, when the motion vectors Vk-2 to Vk-1 are accelerated, the center position Rcen of the search range with a motion vector value larger than the previous vector Vk-1 value. Is set.
Conversely, when the motion vectors Vk-2 to Vk-1 are decelerated, the center position Rcen of the search range is set with a motion vector value smaller than the previous vector Vk-1. Actually, since a vector has a position and directionality, there is a possibility that a vector can be dealt with more appropriately including the case of a direction change.
Accordingly, when the center position Rcen of the search range is set in this way, it is possible to appropriately cope with a change including the direction of movement.
Note that the frame interpolation device 3 according to the present embodiment can also be applied to the case where frame interpolation is performed with the passage of time reversed.

The block diagram which shows the structure of the moving image display apparatus provided with the frame interpolation apparatus which concerns on one Embodiment of this invention. The block diagram which shows the structure of a frame interpolation apparatus. The figure which shows the flame | frame and interpolation frame which are output in time series from a frame interpolation apparatus. Explanatory drawing which produces | generates the interpolation frame between them from two frames. FIG. 4 is an explanatory diagram for searching for an image block pair having a maximum degree of correlation by moving the image block pair symmetrically within a search range set symmetrically with respect to the interpolation target block. Explanatory drawing which shows a mode that the arrival position of the motion vector obtained in the case of the previous interpolation frame was set to the center position of a search range. The flowchart which shows the method of the calculation process of a 1st motion vector and a 2nd motion vector. Explanatory drawing of the effect | action which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 ... Frame interpolation apparatus, 6 ... Frame memory, 7a, 7b ... Interpolation frame production | generation part, 11a ... 1st motion vector calculation part, 11b ... 2nd motion vector calculation part.

Claims (5)

First and second corresponding to each predetermined block in the first and second frame images for each predetermined block in the first interpolated frame image for interpolating between the first and second frame images moving back and forth in time. A first motion vector representing a relative motion amount of each predetermined block with respect to the first image block is calculated by calculating a relative motion amount between the two image blocks within a first search range. First motion vector calculating means for
For each predetermined block in the second interpolated frame image that interpolates between the second and third frame images moving back and forth in time, the second and second corresponding to each predetermined block in the second and third frame images By calculating the relative motion amount between the three image blocks within the second search range, a second motion vector representing the relative motion amount of each predetermined block with respect to the second image block is calculated. If you want to
The position of the first motion vector calculated for each predetermined block is set to the center position of the second search range set on the third frame image to calculate the second motion vector. And a second motion vector calculating means. In the first and second frame images moving back and forth in time, the first motion vector calculating means is geometrically symmetrical with respect to each predetermined block set in the first interpolation frame image. A matching process between the first and second image blocks respectively set is performed within the first search range,
The second motion vector calculation means is configured to geometrically symmetrically position each predetermined block set in the second interpolated frame image in the second and third frame images moving back and forth in time. The frame interpolating apparatus according to claim 1, wherein matching processing between the second and third image blocks respectively set is performed within the second search range.   The frame interpolation apparatus according to claim 1 or 2, wherein the first search range and the second search range have the same number of pixels.   The matching process is a process of calculating a value that maximizes the degree of correlation between corresponding pixels belonging to the first and second image blocks that are geometrically symmetrical with respect to the position of the predetermined block. The frame interpolating apparatus according to claim 2, wherein First and second corresponding to each predetermined block in the first and second frame images for each predetermined block in the first interpolated frame image for interpolating between the first and second frame images moving back and forth in time. A first motion vector representing a relative motion amount of each predetermined block with respect to the first image block is calculated by calculating a relative motion amount between the two image blocks within a first search range. A first motion vector calculating step,
For each predetermined block in the second interpolated frame image that interpolates between the second and third frame images moving back and forth in time, the second and second corresponding to each predetermined block in the second and third frame images By calculating the relative motion amount between the three image blocks within the second search range, a second motion vector representing the relative motion amount of each predetermined block with respect to the second image block is calculated. If you want to
The position of the first motion vector calculated for each predetermined block is set to the center position of the second search range set on the third frame image to calculate the second motion vector. And a second motion vector calculating step.

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