JPH0865680A - Image encoding device and image decoding device - Google Patents

Abstract

PURPOSE: To improve prediction efficiency by adaptively switching a mode for calculating a predictive image with geometrical transformation and a mode for calculating the prediction image with translation for each block. CONSTITUTION: A dividing part 1 for rectangular blocks and a lattice-point motion estimating part 2 calculate the motion vectors of lattice-points by dividing a reference image into rectangles. A translation motion estimating part 3 calculates the moving direction of blocks on the reference image and calculates motion vectors (translation vecotors) in the case of translation of the blocks themselves. A motion compensating predicting part 4 performs motion compensating prediction due to the geometrical transformation, a motion compensating predicting part 5 performs motion compensating prediction by translation, and the respective outputted prediction images are supplied to a prediction image selecting part 6. The prediction image selecting part 6 adaptively selects a prediction image for each block and outputs the prediction image and prediction mode information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image coding apparatus and an image decoding apparatus, and more specifically, in a predictive image forming circuit, a predictive image is obtained by a mode in which a predictive image is obtained by geometric transformation and parallel movement. The present invention relates to an image encoding device and an image decoding device that adaptively switch modes for each block to improve prediction efficiency. For example, it is applied to high-efficiency encoding of image data in digital image processing.

[0002]

2. Description of the Related Art As a method of interframe prediction, a prediction method using affine transformation has been conventionally studied. For example, the publicly known document “Very Low Bitrate Video Coder us”
ing Warping Prediction "(1993 Image Coding Symposium 8-7, pp.167-168) and the well-known document" A Novel Vid. "
eo Coding Scheme Based on Temporal Prediction
"Using Digital Image Warping" (IEEE Inter
national Conferenceon Consumer Electronics, 199
In the method described in 3), the movement of the image is expressed by the deformation of the lattice as shown in FIG. 12, and the reference image (usually the image locally decoded by the encoding device and stored in the frame memory, In the decoding device, the predicted image is created by geometric transformation from the image already decoded and stored in the frame memory. Here, ● represents a grid point (vertex of a rectangular block).

FIG. 13 is a block diagram of a predictive image generating circuit in a conventional image encoding device. In the figure, 32 is a quadrilateral block division unit, 33 is a lattice point motion estimation unit, and 34 is a motion compensation prediction unit. . The division unit 32 into square blocks divides the reference image into squares. When dividing, for example,
A method of dividing by a uniform grid such as a square grid is used regardless of the reference image. Alternatively, a method of dividing by a deformed grid according to the edge on the reference image may be used. The grid point motion estimation unit 33 estimates the motion of the grid point of the reference image and obtains the motion vector of each grid point. This motion vector defines a new deformed grid on the predicted image.

The method shown in FIG. 13 is called "backward motion estimation". First, the grid on the reference image is determined, and then the grid on the prediction target image is determined. On the other hand, a method called “forward motion estimation” may be used.
In this method, a grid (usually a uniform grid) is first defined on the prediction target image, the movement of the grid point is estimated, and a modified grid is newly defined on the reference image by the motion vector of the grid point. Both the conventional example and the present invention can be used in either case. However, for the sake of simplicity, the description will proceed with "backward motion estimation" as an example.

Next, when estimating the position on the original image where the grid point on the reference image has moved ("backward motion estimation")
Case). As a method of motion estimation,
A method (referred to as “block matching”) is used in which an area made up of grid points on the reference image and pixels in the vicinity thereof is taken and which area on the original image matches this area (called “block matching”). Specifically, consider an area of M pixels × N pixels centering on a grid point on the reference image, check the degree of coincidence with an area of the same size on the original image, and set the center of the area with the best degree of coincidence to the lattice point. The point is moved to. A vector representing the movement at this time is called a motion vector. As the degree of coincidence between regions, the sum of absolute values of errors of pixel values in the regions or the sum of absolute values of errors is used. The lattice point motion vector obtained by the lattice point motion estimation unit 33 is encoded by an encoding unit (not shown), incorporated into encoded data, and transmitted or accumulated.

The motion compensation prediction unit 34 obtains a predicted image using the lattice points on the reference image, their motion vectors and the reference image. As a method of obtaining a predicted image, there are methods such as affine transformation using a triangular block and motion vector interpolation in a rectangular block. Regarding these, the publicly known document “Very Low Bitrate Video CoderUsi” is mentioned.
ng Warping Prediction "(1993 Image Coding Symposium 8-7, pp.167-168).

In the encoding device, the difference data between the predicted image and the original image obtained by the motion compensation prediction unit 34 is encoded by an encoding unit (not shown), incorporated into the encoded data, and transmitted or accumulated. . In addition, the encoded data is decoded by a decoding unit (not shown) and added to the predicted image to obtain a decoded image. The decoded image is stored in the frame memory and used as a reference image in the subsequent encoding.

Next, a conventional image decoding apparatus will be described. FIG. 14 is a block diagram of a predictive image generation circuit in a conventional image decoding device. In the figure, 41 is a lattice point motion vector decoding unit, 42 is a motion compensation prediction unit, and 43 is a division unit into rectangular blocks. The lattice point motion vector decoding unit 41 is a unit that decodes the code of the lattice point motion vector incorporated in the encoded data. The output is the motion vector of the lattice point and is supplied to the motion compensation prediction unit 42. The division unit 43 into rectangular blocks and the motion compensation prediction unit 42 have the same functions as those of the encoding device of FIG.

In the decoding device, the same reference image as in the encoding device is obtained, and the motion vector obtained in the lattice point motion vector decoding unit 41 is the same as that obtained in the encoding device. Therefore, the prediction image obtained by the motion compensation prediction unit 42 is the same as that obtained by the encoding device. The predicted image obtained by the motion compensation prediction unit 33 and the decoded value of the difference data obtained by the decoding unit (not shown) are added together to obtain a decoded image. The decoded image is displayed on a display or the like and is also stored in a frame memory (not shown) to be used as a reference image in the subsequent decoding.

[0010]

Problems to be Solved by the Invention FIGS. 15 (a) and 15 (b)
16 (a) to 16 (c) are diagrams for explaining the conventional problems. FIG. 15A represents a part of the reference image, and FIG. 15B represents a part of the prediction target image. As shown in FIG. 15, a rectangular object is moving to the left while rotating counterclockwise against the background of diagonal stripes. ● represents a grid point. Here, paying attention to two blocks (quadrangle abdc and quadrangle befd) formed from grid points a, b, c, d, e, and f on the reference image, the quadrangle abdc on the stationary background is largely deformed, It is a quadrangle ABDC. These two blocks are taken out and shown in FIG.
Shown in (a) and (b).

FIG. 16 (a) shows the two blocks of interest in FIG. 15 (a), and FIG. 16 (b) shows the two blocks of interest in FIG. 15 (b). In such a case, a prediction image created by the conventional method is shown in FIG.
It is (c). It can be seen that the diagonal pattern of the left block is deformed by the geometric transformation and is different from the prediction target image (original image) shown in FIG.

In general, a block on a background image in contact with a moving body changes its shape with the movement of the moving body. According to the conventional method, the predicted image is created by geometric transformation such as deformation or rotation, even if the background image is stationary or moves in parallel. Therefore, there is a problem that the prediction efficiency is reduced. The parallel movement referred to here means that the movement of each pixel is parallel.

17 (a) to 17 (c) are diagrams for explaining other problems in the conventional technique. 17A shows a part of the reference image, and FIG. 17B shows a part of the prediction target image. As shown in FIG. 17, the object 1 is moving in the lower left direction and the object 2 is moving in the upper right direction. Here, attention is paid to two blocks formed from grid points a, b, c, d, e, and f on the reference image. Of these grid points,
Although c and e have moved to C and E on the prediction target image due to the movement of the object, a, b, d and f do not move. In such a case, according to the conventional method, it becomes as shown in FIG. Although the object is moving in parallel, it is distorted due to the geometric transformation. Generally, when a plurality of objects on adjacent blocks move in parallel in different directions, the geometrical distortion as described above occurs.

The present invention has been made in view of such a situation, and in a predictive image forming circuit, a mode for obtaining a predictive image by geometric transformation and a mode for obtaining a predictive image by parallel movement are adaptively applied for each block. It is an object of the present invention to provide an image encoding device and an image decoding device that are capable of improving switching and prediction efficiency.

[0015]

In order to solve the above problems, the present invention (1) in a predictive image forming circuit, a dividing unit for dividing an image into rectangular blocks, and a motion vector of each vertex coordinate of the block And a second motion estimation means for obtaining the motion vector of the parallel movement of the block itself.
Motion estimation means, a plurality of motion compensation prediction means using the motion vector, and a selection means for adaptively selecting the plurality of motion compensation prediction methods for each block, and (2) the above A plurality of motion compensation prediction means using motion vectors of respective vertex coordinates of the block as motion vectors of parallel movement of the block itself; and (3) the motion vector of parallel movement of the block itself Of the motion vector of each vertex coordinate is determined by the comparing and comparing means, and (4) In (1), (2) or (3), the motion compensation prediction method is adaptively selected for each block. At this time, a selecting means for selecting the prediction method from only the motion vector of the vertex coordinates and the information of the already decoded reference image is provided, or (5) the prediction image creation circuit creates a rectangular image. Means for dividing into blocks, a decoding means for decoding the motion vector of each vertex coordinate of the block, a decoding means for decoding the motion vector of the parallel movement of the block itself, and a plurality of motion-compensated predictions using the motion vectors. Means and a control means for switching the plurality of motion compensation prediction methods, and (6) in (5), the motion vector of each vertex coordinate of the block as a motion vector of the parallel movement of the block itself. (7) In (6), the motion vector of the parallel movement of the block itself is calculated and compared with the motion vector of each vertex coordinate of the block. Further, (8) In (5), (6) or (7), when the motion compensation prediction method is adaptively selected for each block, the vertex coordinates are determined. Of the motion vector and the information of the already decoded reference image, and a selecting means for selecting the prediction method.

[0016]

According to the image coding apparatus of the present invention having the above configuration, a plurality of motion compensation prediction methods can be adaptively selected for each block, and the prediction efficiency can be improved. As the plurality of motion compensation prediction means, a motion compensation prediction means by geometric transformation, a motion compensation prediction means by parallel movement, and a determination means for determining a motion vector for performing parallel movement are provided. Can be reduced.
Alternatively, instead of using the prediction image selection means, when adaptively selecting the motion compensation prediction method for each block, a selection means for selecting the prediction method only from the motion vector and the information of the already decoded reference image is provided. Therefore, the prediction mode information can be eliminated.

According to the decoding device configured as described above, it is possible to adaptively select a plurality of motion compensation prediction methods for each block and improve the prediction efficiency. Moreover, since the information of the motion vector and the information of the prediction mode obtained by the encoding device are used, the same prediction image as the prediction image obtained by the encoding device can be obtained. As the plurality of motion compensation prediction means, a motion compensation prediction means by geometric transformation, a motion compensation prediction means by parallel movement, and a determination means for determining a motion vector for performing parallel movement are provided. Can be reduced. Further, since the information of the motion vector and the information of the prediction mode are those obtained by the encoding device, and the means for determining the motion vector is the same as that of the encoding device, it is the same as the prediction image obtained by the encoding device. A predicted image is obtained.

As a control means for switching a plurality of motion-compensated prediction methods, when the motion-compensated prediction method is adaptively selected for each block, the prediction method is selected only from the motion vector and the information of the already decoded reference image. Since the selection means is provided, the prediction mode information can be eliminated. Moreover, since the information of the motion vector is obtained by the encoding device, and the selecting means of the prediction method is the same as that of the encoding device, the same prediction image as the prediction image obtained by the encoding device is obtained. .

[0019]

Embodiments will be described below with reference to the drawings. First, the concept of the present invention will be described with reference to FIG. FIG. 11 shows how a predicted image (one block) of a block of interest (square ABDC) on the predicted image is obtained by the method of the present invention. Similar to the conventional method, the quadrangle abdc on the reference image is transformed using the geometric transformation by the transformation of the lattice, and a predicted image like P1 is obtained. On the other hand, a rectangle a′b′d ′ on the reference image
Another predicted image P2 is obtained by the parallel movement of c '.
In the present invention, these plural predicted images are adaptively selected for each block, and any one of them is used as an actual predicted image.
Here, the parallel movement means that all the pixels in the block move in parallel, which means that the shape of the block does not change and only the position moves.

FIG. 16D is an example of a predicted image created by the present invention. As a method of predicting the block on the left side, there are a method of geometrically transforming the quadrangle abdc in FIG. 16A and a method of moving the portion surrounded by the dotted line in FIG. 16A in parallel. In this case, the latter is adaptively selected, and
The predicted image of 6 (d) is obtained. As can be seen from the figure, the geometric distortion, which was a problem of the conventional method, does not occur. 17D is another example of the predicted image created by the present invention. As a prediction image of the block on the left side, FIG.
The part surrounded by the dotted line of 7 (a) is moved in parallel, and the part surrounded by the alternate long and short dash line of FIG. 17 (a) is moved in parallel as the predicted image of the right block to obtain the predicted image. As can be seen from the figure, the geometrical distortion (see FIG. 17C), which was a problem of the conventional method, does not occur.

FIG. 1 is a block diagram for explaining an embodiment (claim 1) of an image coding apparatus according to the present invention.
Reference numeral 1 is a division unit into rectangular blocks, 2 is a lattice point motion estimation unit, 3 is a parallel motion estimation unit, 4 is a first motion compensation prediction unit, 5 is a second motion compensation prediction unit, and 6 is a predicted image selection. It is a department. The division unit 1 into square blocks and the lattice point motion estimation unit 2 are portions that divide the reference image into squares and obtain the motion vector of the lattice point by the same operation as described in FIG. The motion vector of the lattice point is supplied to the first motion compensation prediction unit 4. The division unit 1 into square blocks
Is also used in other encoding device embodiments, but FIG.
6 is not shown in FIG.

The parallel movement estimation unit 3 is a unit for obtaining the movement direction of a block on the reference image by a method such as block matching. The block matching mentioned above is
It was to check which region of the same shape on the prediction target image matches the region around the grid point. However, here, the block itself is regarded as a region, and it is checked which region of the same shape on the prediction target image matches this region.
As a result, a motion vector (parallel movement vector) when the block itself moves in parallel is obtained. The parallel motion vector is supplied to the second motion compensation prediction unit 5.

The first motion-compensated prediction unit 4 performs motion-compensated prediction by geometric transformation by the same function as that of the motion-compensated prediction unit 33 described with reference to FIG. The output predicted image is supplied to the predicted image selection unit 6. The second motion compensation prediction unit 5 performs motion compensation prediction by parallel movement. The output predicted image is supplied to the predicted image selection unit 6. The prediction image selection unit 6 adaptively selects the prediction image for each block by the method of the present invention, and outputs the prediction image and the prediction mode information. The prediction mode information is coded by a coding unit (not shown), embedded in coded data, and transmitted or accumulated. As a method of selecting the predicted image, a method of minimizing an error with the original image, a method of minimizing a weighted error with the original image, or the like can be considered. These will be described below.

FIG. 2 is a block diagram showing an example of the predicted image selection unit in FIG. 1, in which 7 is a first error calculation unit, 8 is a second error calculation unit, and 9 is a selection unit. Here, although there are two types of predicted images, the present invention is not limited to this. The first error calculation unit 7 is a unit that inputs the data of the original image and the predicted image for one block and calculates the prediction error. The prediction error is calculated by using the pixel value f (n) of the original image and the pixel value f (n) ′ of the predicted image,

[0025]

[Equation 1]

Is calculated by However, n is the pixel number in the block, and N is the number of pixels in the block.
Although a prediction error due to a squared error is shown here, an absolute value error may be used. The second error calculation unit 8 is a unit that calculates a prediction error by the same function as that of the first error calculation unit 7. The selection unit 9 compares the prediction errors and outputs the prediction image and the prediction mode information having the smallest prediction error. For example, if the error of the second error calculation unit 8 is the minimum, the predicted image is selected and output. Moreover, the information showing a prediction image is output as prediction mode information. When there are two types of prediction methods, for example, if the prediction mode information is represented by a fixed-length code, one bit is required for each block.

FIG. 3 is a block diagram showing another example of the prediction image selection unit in FIG. 1, in which 10 is a first orthogonal transformation unit,
11 is a second orthogonal transformation unit, 12 is a third orthogonal transformation unit,
Other parts that have the same functions as those in FIG. 2 are given the same reference numerals. 1st orthogonal transformation part 10-3rd orthogonal transformation part 12
Converts the input pixel value for one block into a two-dimensional orthogonal transform to a frequency component. The first error calculating unit 7 and the second error calculating unit 8 in FIG.
This is a part for calculating a weighted error (prediction error) between (k) and the orthogonal transformation coefficient g (k) 'of the predicted image as follows.

[0028]

[Equation 2]

Here, k is the number of the orthogonal transform coefficient, N is the number of pixels in the block, and w (k) is a predetermined weight. Although the prediction error due to the squared error is shown here,
You may use an absolute value error. For example, by setting the weight w (k) large at low frequencies and small at high frequencies,
A prediction error that matches the human visual characteristics is calculated. FIG.
The selecting unit 9 of selects the predicted image by the same operation as the selecting unit 9 of FIG. 2, and outputs the predicted image and the prediction mode information.

As described above, the coding apparatus shown in FIG. 1 can switch a plurality of motion compensation prediction methods. That is, it is possible to adaptively switch, for each block, the motion prediction method using geometric transformation and the motion prediction method by parallel movement. As a result, it is possible to improve the prediction efficiency and the coding efficiency.

FIG. 4 is a block diagram for explaining another embodiment (claim 2) of the image coding apparatus according to the present invention, in which 13 is a third motion compensation prediction unit and 14 is a fourth motion compensation prediction unit. The motion-compensated prediction unit 15 is a fifth motion-compensated prediction unit, and the other parts having the same operations as in FIG. 1 are denoted by the same reference numerals. The grid point motion estimation unit 2 is a unit that obtains a motion vector of a grid point by the same operation as that described in FIG. The motion vector of the lattice point is supplied to the first motion compensation prediction unit 4 to the fifth motion compensation prediction unit 15. The first motion-compensated prediction unit 4 performs motion-compensated prediction by geometric transformation by the same operation as the motion-compensated prediction unit 33 described with reference to FIG. The output predicted image is supplied to the predicted image selection unit 6.

The second motion compensation prediction unit 5 to the fifth motion compensation prediction unit 15 perform motion compensation prediction by parallel movement. The motion vector used for prediction is the motion vector of the four grid points of the block of interest. Assuming that the motion vectors of the respective lattice points are V1, V2, V3 and V4, the second motion compensation prediction unit 5 uses the motion vector V1 as the third motion compensation prediction unit 1
3 uses the motion vector V2, the fourth motion compensation prediction unit 14 uses the motion vector V3, and the fifth motion compensation prediction unit 15 uses the motion vector V4 to perform motion compensation prediction by parallel movement. The created predicted image is supplied to the predicted image selection unit 6, respectively. The predicted image selection unit 6 adaptively selects a predicted image by the method of the present invention and outputs the predicted image and prediction mode information. Specifically, the method already described (FIGS. 2 and 3) is used. However, here, there are five types of predicted images.

As described above, a plurality of motion compensation prediction methods can be switched by the encoding device shown in FIG. That is, it is possible to adaptively switch, for each block, the motion prediction method using geometric transformation and the four motion prediction methods by parallel movement. As a result, it is possible to improve the prediction efficiency and the coding efficiency. Also,
Since it is not necessary to encode the motion vector indicating the parallel movement of blocks, the amount of encoded data can be reduced.

FIG. 5 is a block diagram for explaining still another embodiment (claim 3) of the image coding apparatus according to the present invention.
In the figure, 16 is a parallel movement vector determination unit, and in addition, FIG.
The same reference numerals are attached to the parts having the same functions as. FIG.
The difference is that the motion compensation prediction is performed by parallel movement (the parallel movement vector determination unit 16 and the second motion compensation prediction unit 5).

The parallel movement vector determination unit 16 performs parallel movement of the block itself based on the motion vectors of the four lattice points belonging to one block and the reference image (all of which are information obtained by the decoding device). Determine the motion vector to represent. The translation vector obtained here is supplied to the second motion compensation prediction unit 5. For example, a parallel movement vector for obtaining an average value of four lattice point motion vectors is used. In this case, since the information of the reference image is not used, the reference image is not input to the translation vector determination unit 16.

Alternatively, the following method can be considered as another parallel movement vector determination method. That is, the parallel movement vector of the block of interest is searched from the reference image one frame before and the reference image two frames before by the block matching as described in the description of the embodiment shown in FIG. The motion vector obtained here is taken as a parallel movement vector to be obtained. Alternatively, the four lattice point motion vectors and their average vector may be compared with the searched motion vector, and the closest one may be used as the parallel movement vector.

The second motion compensation prediction unit 5 in FIG.
Motion compensation prediction is performed by parallel movement based on the input motion vector. The predicted image selection unit 6 selects a predicted image having a small prediction error from the two types of predicted images, and outputs the selected predicted image and prediction mode information. The selection method is the same as that shown in FIGS. According to the encoding apparatus of the present embodiment, the prediction mode information needs only 1 bit per block, so the amount of data related to the prediction mode information can be reduced.

FIG. 6 is a block diagram for explaining still another embodiment (claim 4) of the image coding apparatus according to the present invention.
In the figure, 17 is a control unit, 18 is a prediction mode selection unit, and other parts having the same operations as those in FIG. The difference from FIG. 5 is that the prediction image selection unit 6 is eliminated and a prediction mode selection unit 18, a control unit 17, switches and switches are provided instead.

The prediction mode selection unit 18 determines the prediction mode based on the information obtained by the decoding device such as the motion vector and the reference image. Mode 0 represents motion-compensated prediction by geometric transformation, and mode 1 represents motion-compensated prediction by parallel movement. The determined prediction mode is supplied to the control unit 17.

For example, a change in the size of the block of interest can be known from the motion vector. When a block changes greatly, it is often caused by the motion of an adjacent block, and the focused block itself is often stationary or moving in parallel. Therefore, the motion compensation prediction mode by parallel movement is selected. That is, the change in the number of pixels contained in a block is examined, and if the change is larger than the threshold value, the motion compensation prediction mode by parallel movement is selected, and in other cases, the motion compensation prediction mode by geometric transformation is selected. To do.

Alternatively, the following method can be considered as another prediction mode selection method. That is, the motion vector of the block of interest is searched for from the reference image one frame before and the reference image two frames before by block matching. If the minimum error of block matching at this time is smaller than the threshold value, the motion compensation prediction mode by parallel movement is selected, and in other cases, the motion compensation prediction mode by geometric transformation is selected. The threshold value described here is determined theoretically or empirically. These may be determined in advance, or may be changed manually or automatically as appropriate.

The control unit 17 controls the switches and the switches based on the prediction mode determined as described above. That is, when the prediction mode is 0, the switch and the switch are set to the side of the first motion compensation prediction unit 4 to perform the motion compensation prediction by geometric transformation. When the prediction mode is 1, the switch and the switch are set to the second motion compensation prediction unit 5 side to perform motion compensation prediction by parallel movement. As described above, according to the encoding apparatus of the present embodiment, the prediction mode is determined based on the information obtained by the decoding apparatus as well, so that it is not necessary to encode the prediction mode information and the data amount can be reduced.

FIG. 7 is a block diagram for explaining an embodiment (claim 5) of the image decoding apparatus according to the present invention.
1 is a control unit, 22 is a lattice point motion vector decoding unit, 23 is a parallel motion vector decoding unit, 24 is a division unit into rectangular blocks, 25 is a first motion compensation prediction unit, and 26 is a second motion compensation prediction unit. Is. The present embodiment is a decoding device that decodes encoded data created by the encoding device according to claim 1.

The lattice point motion vector decoding unit 22 is a unit that decodes a lattice point motion vector from encoded data by the same operation as that described in FIG. The translation vector decoding unit 23 is a unit that decodes a translation vector from encoded data. Dividing unit 24 into rectangular blocks
Is a part that divides the reference image into quadrangles by the same operation as that described in FIG. The division unit 24 into the rectangular blocks is also used in the other embodiments of the decoding device, but is not shown in FIGS.

The control unit 21 controls the switch based on the prediction mode information in the encoded data according to the method of the present invention. That is, when the prediction mode information represents motion-compensated prediction by geometric transformation, the switch is set to the first motion-compensated prediction unit 25 side, and when the prediction mode information represents motion-compensated prediction by parallel movement, the switch is switched to the second switch. Motion compensation prediction unit 2
Switch to the 6 side. The motions of the first motion compensation prediction unit 25 and the second motion compensation prediction unit 26 are exactly the same as those of the encoding device shown in FIG.

As described above, in the decoding device shown in FIG. 7, the same prediction mode as that of the encoding device is selected and the same prediction image is obtained. This predicted image and the decoded value of the difference data obtained by the decoding unit (not shown) are added,
A decoded image is obtained. The decoded image is displayed on the display and stored in a frame memory (not shown).
It is used as a reference image in the subsequent decoding.

FIG. 8 is a block diagram for explaining another embodiment (claim 6) of the image decoding apparatus according to the present invention.
Reference numeral 27 is a third motion compensation prediction unit, 28 is a fourth motion compensation prediction unit, 29 is a fifth motion compensation prediction unit, and other parts having the same operations as in FIG. . The present embodiment is a decoding device that decodes the encoded data created by the encoding device of claim 2.

The lattice point motion vector decoding unit 22 is a portion for decoding the lattice point motion vector from the encoded data by the same operation as that described in FIG. The control unit 21 controls the switches and the switches based on the prediction mode information in the encoded data by the method of the present invention. That is, when the prediction mode information represents motion compensation prediction by geometric transformation, the switch and the switch are set to the first motion compensation prediction unit 25 side, and the prediction mode information is the motion vector V.
To represent motion-compensated prediction by translation using 1
The switch and the switch are the second motion compensation prediction unit 26.
Switch the switch to the side of. Switching from the third motion compensation prediction unit 27 to the fifth motion compensation prediction unit 29 is performed in the same manner.

The operations of the first motion compensation prediction unit 25 to the fifth motion compensation prediction unit 29 are exactly the same as those of the encoding device shown in FIG. As described above, in the decoding device shown in FIG. 8, the same prediction mode as that of the encoding device is selected and the same prediction image is obtained. The subsequent operation is similar to that of the embodiment shown in FIG.

FIG. 9 is a block diagram for explaining still another embodiment (Claim 7) of the image decoding apparatus according to the present invention. In the figure, 30 is a translation vector determination unit, and FIG. Portions having the same function are designated by the same reference numerals. The present embodiment is a decoding device for decoding encoded data created by the encoding device according to claim 3.

The lattice point motion vector decoding unit 22 is a unit for decoding the lattice point motion vector from the encoded data by the same operation as that described in FIG. The control unit 21 controls the switches and the switches based on the prediction mode information in the encoded data by the method of the present invention. That is, when the prediction mode information represents motion-compensated prediction by geometric transformation, the switch and the switch are set to the first motion-compensated prediction unit 25 side, and when the prediction mode information represents motion-compensated prediction by parallel movement, the switch is switched. And the switch is on the side of the second motion compensation prediction unit 26.

The parallel motion vector determination unit 30 determines the parallel motion vector used in the second motion compensation prediction unit 26 by the same function as that of FIG. The functions of the first motion compensation prediction unit 25 and the second motion compensation prediction unit 26 are exactly the same as those of the coding device shown in FIG.
As described above, in the decoding device shown in FIG. 9, the same prediction mode as that of the encoding device is selected and the same prediction image is obtained. The subsequent operation is similar to that of the embodiment shown in FIG.

FIG. 10 is a block diagram for explaining still another embodiment (claim 8) of the image decoding apparatus according to the present invention.
In the figure, reference numeral 31 is a prediction mode selection unit, and other parts having the same operations as those in FIG. 9 are designated by the same reference numerals. The present embodiment is a decoding device for decoding encoded data created by the encoding device according to claim 4.

The lattice point motion vector decoding unit 22 is a unit for decoding the lattice point motion vector from the encoded data by the same operation as that described in FIG. The prediction mode selection unit 31 determines the prediction mode based on the information such as the motion vector and the reference image by the same operation as that of FIG.
The determined prediction mode is supplied to the control unit 21.

The control unit 21 controls the switches and the switches based on the prediction mode information in the encoded data by the same function as that of FIG. The parallel motion vector determination unit 30 determines the parallel motion vector used in the second motion compensation prediction unit 26 by the same function as that of FIG. Also, the functions of the first motion compensation prediction unit 25 and the second motion compensation prediction unit 26 are exactly the same as those of the encoding device shown in FIG. As described above, in the decoding device shown in FIG. 10, the same prediction mode as that of the encoding device is selected and the same prediction image is obtained. The subsequent operation is similar to that of the embodiment shown in FIG.

The embodiments of the encoding device and the decoding device described here mainly obtain the motion vector in only one direction in time and perform motion compensation prediction by this, but of course, in both directions in time. Alternatively, motion compensation prediction may be performed by obtaining a motion vector (that is, from preceding and following reference images). In the prediction by the geometric transformation, the problem as shown in FIG. 16C cannot be solved even by using the bidirectional motion compensation prediction. By adaptively switching the motion compensation by the parallel movement and the motion compensation by the geometric transformation using the present invention, even when a plurality of objects having different motions are overlapped, or when the objects include rotation, deformation, etc. A good predicted image can be obtained.

[0057]

As is apparent from the above description, the present invention has the following effects. (1) Effect corresponding to claim 1: In the predictive image generating circuit of the image encoding device, the dividing means for dividing into rectangular blocks, the motion estimating means for obtaining the motion vector of each vertex coordinate of the block, and the block itself A motion estimation means for obtaining a parallel motion vector, a plurality of motion compensation prediction means,
Since the plurality of motion-compensated prediction methods is adaptively selected for each block, the plurality of motion-compensated prediction methods can be adaptively selected for each block, and the prediction efficiency can be improved. Thus, for example, according to the conventional method, even when the background pattern is distorted by the geometric transformation like the block on the left side of FIG. 16C, according to the present invention, the dotted line of FIG. A good predicted image can be created by obtaining a predicted image from a part by parallel movement. Further, according to the conventional method, even when the pattern of the object is distorted by the geometrical transformation as shown in FIG. 17C, according to the present invention, the dotted line portion and the one-dot chain line portion of FIG. A favorable predicted image can be created by obtaining the predicted image by moving. (2) Effect corresponding to claim 2: Since a plurality of motion compensation prediction means using the motion vector of each vertex coordinate of the block as a motion vector of the parallel movement of the block itself are provided, the motion vector of the lattice point is provided. If the motion vector of the parallel movement of the block itself is expressed by using, the data amount can be reduced because only the motion vector of the lattice point needs to be encoded. (3) Effect corresponding to claim 3: In order to determine the motion vector of the parallel movement of the block itself, since the motion vector calculation and comparison means of the vertex coordinates of the block are provided, a plurality of motion compensation predictions are provided. For example, if motion-compensated prediction by geometric transformation or motion-compensated prediction by parallel movement is used to determine the motion vector for parallel movement based on the information obtained by the decoding device, the prediction mode information can be reduced. And the amount of data can be reduced. (4) Effect corresponding to claim 4: Instead of using the predictive image selecting means, when adaptively selecting the motion compensation predictive method for each block, only the motion vector and the information of the already decoded reference image are used. Since the selection means for selecting the prediction method is provided, if the prediction method is selected only from the information of the already decoded reference image of the motion vector of the lattice point, the prediction mode information can be eliminated and the data amount can be reduced. (5) Effect corresponding to claim 5: In the predictive image generation circuit of the image decoding device, dividing means for dividing into rectangular blocks, decoding means for decoding the motion vector of the vertex coordinates of the blocks, and parallel movement of the blocks themselves. Since it is provided with a decoding means for decoding the motion vector, a plurality of motion compensation prediction means, and a control means for switching the plurality of motion compensation prediction methods, a plurality of motion compensation prediction methods are adaptively selected for each block. Therefore, the prediction efficiency can be improved. Moreover, since the information of the motion vector and the information of the prediction mode obtained by the encoding device are used, the same prediction image as the prediction image obtained by the encoding device can be obtained. (6) Effect corresponding to claim 6: Since a plurality of motion compensation prediction means using motion vectors of parallel movement of blocks themselves are provided, motion vectors of parallel movement of blocks themselves are used by using motion vectors of lattice points. By representing only the motion vector of the lattice point as the motion vector, the processing amount can be reduced. (7) Effect corresponding to claim 7: In order to determine the motion vector of the parallel movement of the block itself, since a motion vector calculation and comparison means of each vertex coordinate of the block is provided, a plurality of motion compensation predictions are provided. For example, if motion-compensated prediction by geometric transformation or motion-compensated prediction by parallel movement is used to determine the motion vector for parallel movement based on the information obtained by the decoding device, the prediction mode information is reduced. be able to. (8) Effect corresponding to claim 8: When the motion compensation prediction method is adaptively selected for each block as the control means for switching a plurality of motion compensation prediction methods, the motion vector of the vertex coordinates and the motion vector already decoded Since the selection means for selecting the prediction method only from the information of the reference image is provided, the prediction method is selected only from the motion vector of the lattice point and the information of the already decoded reference image, so that the prediction mode information can be eliminated. .

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of an image encoding device according to the present invention.

FIG. 2 is a configuration diagram showing an example of a predicted image selection unit in FIG.

FIG. 3 is a configuration diagram showing another example of a predicted image selection unit in FIG.

FIG. 4 is a configuration diagram for explaining another embodiment of the image encoding device according to the present invention.

FIG. 5 is a configuration diagram for explaining still another embodiment of the image encoding device according to the present invention.

FIG. 6 is a configuration diagram for explaining still another embodiment of the image encoding device according to the present invention.

FIG. 7 is a configuration diagram for explaining an embodiment of an image decoding device according to the present invention.

FIG. 8 is a configuration diagram for explaining another embodiment of the image decoding device according to the present invention.

FIG. 9 is a configuration diagram for explaining yet another embodiment of the image decoding device according to the present invention.

FIG. 10 is a configuration diagram for explaining still another embodiment of the image decoding device according to the present invention.

FIG. 11 is a diagram for explaining motion compensation prediction of the present invention.

[Fig. 12] Fig. 12 is a diagram for describing motion compensation prediction by conventional geometric transformation.

[Fig. 13] Fig. 13 is a configuration diagram of a predicted image creation circuit in a conventional image encoding device.

[Fig. 14] Fig. 14 is a configuration diagram of a predicted image creation circuit in a conventional image decoding device.

FIG. 15 is a diagram illustrating an example of a reference image and a prediction target image.

FIG. 16 is a diagram showing a comparative example of predicted images according to the conventional invention.

FIG. 17 is a diagram showing another comparative example of predicted images according to the related art and the present invention.

[Explanation of symbols]

1 ... Division into rectangular blocks, 2 ... Lattice point motion estimation unit, 3 ... Parallel motion estimation unit, 4 ... First motion compensation prediction unit, 5 ... Second motion compensation prediction unit, 6 ... Prediction image selection Department,
7 ... 1st error calculation part, 8 ... 2nd error calculation part, 9 ... selection part, 10 ... 1st orthogonal transformation part, 11 ... 2nd orthogonal transformation part, 12 ... 3rd orthogonal transformation part, 13 ... 3rd motion compensation prediction part, 14 ... 4th motion compensation prediction part, 15 ... 5th motion compensation prediction part, 16 ... Parallel motion vector determination part, 17 ... Control part, 18 ... Prediction mode selection part, 21 ... control unit, 22 ...
Lattice point motion vector decoding unit, 23 ... Translation vector decoding unit, 24 ... Dividing unit into rectangular blocks, 25 ... First motion compensation prediction unit, 26 ... Second motion compensation prediction unit, 27 ... Third motion Compensation prediction unit, 28 ... fourth motion compensation prediction unit, 2
9 ... Fifth motion compensation prediction unit, 30 ... Translation vector determination unit, 31 ... Prediction mode selection unit.

Claims (8)

[Claims] 1. A predictive image generation circuit, comprising: a dividing means for dividing an image into rectangular blocks; a first motion estimating means for obtaining a motion vector at each vertex coordinate of the block; and a motion vector for parallel movement of the block itself. An image characterized by comprising: a second motion estimation means for obtaining, a plurality of motion compensation prediction means using the motion vector, and a selection means for adaptively selecting the plurality of motion compensation prediction methods for each block. Encoding device. 2. The image coding apparatus according to claim 1, further comprising a plurality of motion compensation prediction units that use a motion vector of each vertex coordinate of the block as a motion vector of parallel movement of the block itself. 3. The image coding apparatus according to claim 1, wherein the motion vector of the parallel movement of the block itself is determined by a calculation and comparison means of the motion vector of each vertex coordinate of the block. 4. When the motion compensation prediction method is adaptively selected for each block, a selection means for selecting the prediction method from only the motion vector of the vertex coordinates and the information of the already decoded reference image is provided. The image coding apparatus according to claim 1, 2, or 3. 5. A predicting image forming circuit, a dividing unit for dividing an image into rectangular blocks, a decoding unit for decoding a motion vector of each vertex coordinate of the block, and a decoding unit for decoding a parallel motion vector of the block itself. An image decoding apparatus comprising: means, a plurality of motion compensation prediction means using the motion vector, and a control means for switching the plurality of motion compensation prediction methods. 6. The image decoding apparatus according to claim 5, further comprising a plurality of motion compensation prediction units that use a motion vector of each vertex coordinate of the block as a motion vector of parallel movement of the block itself. 7. The image decoding apparatus according to claim 6, wherein the motion vector of the parallel movement of the block itself is determined by a calculation and comparison means of the motion vector of each vertex coordinate of the block. 8. When the motion compensation prediction method is adaptively selected for each block, a selection means for selecting the prediction method from only the motion vector of the vertex coordinates and the information of the already decoded reference image is provided. The image decoding device according to claim 5, 6 or 7.