JP6740534B2 - Encoding device, decoding device and program - Google Patents

Description

The present invention relates to an encoding device, a decoding device and a program.

In a moving image coding method represented by H.265/HEVC (High Efficiency Video Coding), there are two types of inter prediction using inter-frame temporal correlation and intra prediction using intra-frame spatial correlation. It is configured to perform prediction while switching predictions to generate a residual signal, and then perform orthogonal transform processing, loop filter processing, and entropy coding processing to output the obtained stream.

In the intra prediction in HEVC, a total of 35 types of modes such as Planar prediction, DC prediction, and directional prediction are prepared, and the intra prediction is performed using adjacent decoded reference pixels according to the mode determined by the encoder. Has been done.

Here, in intra prediction, a CU (Coding Unit) located in the upper leftmost position in a frame or the like in which there is no adjacent decoded reference pixel has a specified value (“512” for a 10-bit moving image). Is configured to generate a reference pixel used when generating a predicted image.

Further, in the conventional HEVC, since the encoding process is performed in raster scan order from the upper left, the reference pixel may not be decoded. In such a case, the predicted image is generated using a value obtained by extrapolating the nearest decoded reference pixel to the 0th order.

The CU is divided into a plurality of blocks (TU: Transform Unit) and subjected to orthogonal transform processing. In HEVC, the intra prediction mode indicating the type of intra prediction to be applied is common in the CU, and prediction is performed using a common intra prediction mode for a plurality of TUs.

In intra prediction, as shown in FIG. 7, the reference pixel N located at the lower left or upper right of CU#X is often undecoded due to the encoding process in the raster scan order, and in such a case, it is not already decoded. When the direction prediction is performed from the direction in which the reference pixel exists, there is a problem that the prediction accuracy is lowered and the coding efficiency is reduced.

Hereinafter, such a problem will be specifically described with reference to FIGS. 8A to 8D. FIG. 8 shows an example of intra prediction in conventional HEVC.

In this example, as shown in FIG. 8A, all the reference pixels of CU#A1 (the upper left CU in the frame) have been decoded as in the case of the example of FIG. Similarly, as shown in FIG. 8C, all the reference pixels of CU#A3 (the lower left CU in the frame) have been decoded.

On the other hand, as shown in FIG. 8B, reference pixels W1 to W3 located in CU#A1 have been decoded, but reference pixels B1 to B4 located in CU#A3 have been decoded. Since it does not exist, it cannot be directly used as a reference pixel when generating a predicted image of CU#A2 (CU at the upper right of the frame).

Therefore, in the conventional HEVC, as shown in FIG. 8B, the value of the reference pixel W1 located at the bottom of the decoded reference pixels W1 to W3 located in CU#A1 is set in CU#A3. Are defined to be copied to the undecoded reference pixels B1 to B4 located in the same column.

Similarly, in the conventional HEVC, as shown in FIG. 8D, the value of the reference pixel B1 located at the bottom of the decoded reference pixels B1 to B3 located in CU#A3 is set to the value of CU#A3. It is specified to copy to the undecoded reference pixel P3 located in the same column in the CU existing on the lower side.

Therefore, when the directional prediction is performed from the lower left to the upper right as in the example of FIG. 8, most of the generated predicted images are composed of undecoded reference pixels filled with a copy, and thus the prediction accuracy is high. There is a problem in that the coding efficiency is reduced and the coding efficiency is reduced.

In order to solve such a problem, in intra prediction in which TU partitioning is performed, as a coding processing order for a plurality of TUs existing in a CU, a raster scan order (for example, Z type), U type, or X type is used. There is known a technique for improving the prediction accuracy by giving a degree of freedom in the coding order such as (see Non-Patent Document 1).

Mochizuki et al., “Applied Intra Prediction Method Based on Average Coordinates”, Research Report of Information Processing Society of Japan, vol, 2012-AVM-77, No. 12

However, in the technique defined in Non-Patent Document 1 described above, it is necessary to transmit a flag indicating what encoding processing order is to be used for each CU, which increases the amount of information to be transmitted. , In order to select which coding processing order is better among all the coding processing orders, it is necessary to try all combinations on the coding device side, which increases the calculation time on the coding device side. There was a problem.

Therefore, the present invention has been made to solve the above-described problems, and it is possible to perform prediction without increasing the amount of information transmitted by the encoding device and without increasing the calculation time on the encoding device side. An object of the present invention is to provide an encoding device, a decoding device, and a program that can improve accuracy and encoding efficiency.

A first feature of the present invention is an encoding device configured to divide an original image of a frame forming a moving image into blocks to be encoded and to encode the blocks, based on an intra prediction mode. A combination area determining unit configured to determine a combination area in which a predicted image is generated from adjacent pixels that have not been decoded in the encoding target block, and whether or not the combination area is included in the combination area, And an intra prediction unit configured to change a method of generating a predicted image of each area.

A second feature of the present invention is a decoding device configured to divide an original image of a frame unit forming a moving image into blocks to be encoded and decode the block, based on an intra prediction mode. A combination area determination unit configured to determine a combination area in which a predicted image is generated from adjacent pixels that have not been decoded in the block to be encoded, and each area based on whether or not the combination area is included in the combination area. And an intra-prediction unit configured to change the method of generating the predicted image of 1.

A third feature of the present invention is summarized as a program for causing a computer to function as the encoding device according to the first or second feature described above.

A fourth feature of the present invention is summarized as a program for causing a computer to function as the decoding device according to the first or second feature described above.

ADVANTAGE OF THE INVENTION According to the present invention, an encoding device capable of improving prediction accuracy and encoding efficiency without increasing the amount of information transmitted by the encoding device and without increasing the calculation time on the encoding device side. , A decoding device and a program can be provided.

FIG. 1 is a functional block diagram of an encoding device 1 according to the first embodiment. FIG. 2 is a diagram illustrating an example of how a predicted image is generated in the first embodiment. FIG. 3 is a diagram showing an example of how a predicted image is generated in the first embodiment. FIG. 4 is a functional block diagram of the decoding device 3 according to the first embodiment. FIG. 5 is a flowchart showing operations of the encoding device 1 and the decoding device 3 according to the first embodiment. FIG. 6 is a diagram showing an example of how a predicted image is generated in the second embodiment. FIG. 7 is a diagram showing an example of how a predicted image is generated in the conventional HEVC. FIG. 8 is a diagram showing an example of how a predicted image is generated in the conventional HEVC.

(First embodiment)
Hereinafter, the encoding device 1 and the decoding device 3 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 5. Here, the encoding device 1 and the decoding device 3 according to the present embodiment are configured to support intra prediction in HEVC.

The encoding device 1 according to the present embodiment is configured to divide an original image of a frame forming a moving image into encoding target blocks and perform encoding. In the present embodiment, it is assumed that all pixels adjacent to the left side and the upper side of the CU to be encoded have been decoded.

In addition, the encoding device 1 according to the present embodiment may be configured so that the CU can be divided into a plurality of TUs. Therefore, in the present embodiment, the target block to be encoded may be a CU or a TU. Hereinafter, in the present embodiment, a case where a CU is used as an encoding target block will be described as an example.

Further, in the present embodiment, the case where the raster scan order (Z type as shown in FIG. 7 and FIG. 8) used in the conventional HEVC is used as the encoding order and the decoding order of the CU is taken as an example. However, other encoding order and decoding order such as U-type and X-type may be used as the encoding order and decoding order.

As shown in FIG. 1, the encoding device 1 according to the present embodiment has an intra prediction mode determination unit 11, a synthesis region determination unit 12, an intra prediction unit 13, a residual signal generation unit 14, and an orthogonal transform/ It includes a quantizer 15, an inverse orthogonal transform/inverse quantizer 16, a locally decoded image generator 17, a memory 18, and an entropy encoder 19.

The intra prediction mode determination unit 11 is configured to determine the optimum intra prediction mode applied to the CU.

The synthesis area determination unit 12 is configured to determine the synthesis area X in which a prediction image is generated from adjacent pixels that have not been decoded in the CU, based on the intra prediction mode determined by the intra prediction mode determination unit 11. There is.

Specifically, as shown in FIG. 2, when the direction of the intra prediction mode determined by the intra prediction mode determination unit 11 is from the lower left to the upper right, that is, the synthesis region determination unit 12 (that is, from the lower left to the upper right). (When the directional prediction is performed toward ), the synthesis area X in which the prediction image is generated is determined from the undecoded adjacent pixels B1 to B4 in CU#A2.

The present invention is also applied to the case where the direction of the intra prediction mode determined by the intra prediction mode determination unit 11 is from the upper right to the lower left (that is, when the directional prediction is performed from the upper right to the lower left). Although possible, an example in which the direction of the intra prediction mode determined by the intra prediction mode determination unit 11 is from the lower left to the upper right (that is, the direction prediction is performed from the lower left to the upper right) will be described below. To explain.

In the drawings of this specification, the arrow indicating the direction of the intra prediction mode (prediction direction) is directed from the pixel of the intra prediction to the reference pixel, similarly to the description in the HEVC standard (hereinafter the same). ..

The intra prediction unit 13 is configured to change the method of generating the predicted image of each region, based on whether the intra prediction unit 13 is included in the synthesis region X determined by the synthesis region determination unit 12.

Specifically, as illustrated in FIG. 3A, the intra prediction unit 13 is a region that is not included in the synthesis region X in CU#A2 (that is, a region in which the reference pixels W1 to W3 have been decoded). In Y, the intra prediction mode determined by the intra prediction mode determination unit 11 is used to generate a predicted image based on the decoded reference pixels W1 to W3.

On the other hand, as illustrated in FIG. 3B, the intra prediction unit 13 predefines an area included in the composite area X in CU#A2 (that is, an area in which the reference pixels B2 to B4 have not been decoded). The prediction method is used to generate a prediction image.

Here, the predefined prediction method includes, for example, intra prediction such as DC prediction and Planar prediction, as well as a prediction method that generates a predicted image by averaging the values of adjacent decoded reference pixels.

It should be noted that if the coding apparatus 1 and the decoding apparatus 3 have previously determined such a prediction method, the prediction method can be applied from the coding apparatus 1 to the decoding apparatus 3 regardless of the prediction method used. There is no need to transmit a new flag to indicate.

In addition, the synthesis area determined by the synthesis area determination unit 12 can be uniquely determined depending on the direction of the intra prediction mode and whether or not adjacent pixels have been decoded. However, it is not necessary to newly transmit a flag indicating which area is the combined area.

For example, as illustrated in FIG. 3B, the intra prediction unit 13 uses the Planar prediction at the position of the pixel X1 in the area included in the combined area X in CU#A2 to use the pixels W3 and D1. , The pixel D2 and the pixel D4 may be combined to generate the predicted image. Here, the value of the pixel B4 is copied to the pixel D4, and the value of the pixel W1 is copied to the pixel B4.

The residual signal generation unit 14 is configured to generate a residual signal based on the difference between the predicted image generated by the intra prediction unit 13 and the original image.

The orthogonal transform/quantization unit 15 is configured to perform an orthogonal transform process and a quantization process on the residual signal generated by the residual signal generation unit 14 to generate a quantized transform coefficient. ..

The inverse orthogonal transformation/inverse quantization unit 16 again performs inverse quantization processing and inverse orthogonal transformation processing on the quantized transform coefficient generated by the orthogonal transformation/quantization unit 15, and outputs the quantized residue. It is configured to generate a difference signal.

The locally decoded image generation unit 17 generates a locally decoded image by adding the prediction image generated by the intra prediction unit 13 to the quantized residual signal generated by the inverse orthogonal transform/inverse quantization unit 16. Is configured to.

The memory unit 18 is configured to hold the locally decoded image generated by the locally decoded image generation unit 17 so that it can be used as a reference image.

The entropy coding unit 19 is configured to perform entropy coding processing on flag information including the intra prediction mode determined by the intra prediction mode determination unit 11 and the quantized transform coefficient, and output the stream. There is.

In addition, the decoding device 3 according to the present embodiment is configured to divide an original image of a frame forming a moving image into CUs and decode the divided CUs. Further, the decoding device 3 according to the present embodiment is configured to be able to divide the CU into a plurality of TUs, as with the encoding device 1 according to the present embodiment.

As illustrated in FIG. 4, the decoding device 3 according to the present embodiment includes an entropy decoding unit 31, a synthesis region determination unit 32, an intra prediction unit 33, an inverse quantization/inverse conversion unit 34, and a locally decoded image generation. It includes a unit 35 and a memory unit 36.

The entropy decoding unit 31 is configured to decode the transform coefficient, flag information and the like from the stream output from the encoding device 1. Here, the transform coefficient is a quantized transform coefficient obtained as a signal encoded by dividing the original image in frame units into CUs by the encoding device 1. The flag information also includes accompanying information such as the prediction mode.

The synthesis area determination unit 32 is configured to determine the synthesis area X in which a prediction image is generated from adjacent pixels that have not been decoded in the CU, based on the intra prediction mode output by the entropy decoding unit 31.

Specifically, as shown in FIG. 2, when the direction of the intra prediction mode output by the entropy decoding unit 31 is from the lower left to the upper right (that is, from the lower left to the upper right), as shown in FIG. (When the directional prediction is performed), the synthesis area X in which the predicted image is generated from the undecoded adjacent pixels B1 to B4 in CU#A2 may be determined.

The intra prediction unit 33 may be configured to generate a predicted image by using the synthesis region X determined by the synthesis region determination unit 32 and the intra prediction mode output by the entropy decoding unit 31.

Specifically, the intra prediction unit 33, similar to the intra prediction unit 13, determines the method of generating the predicted image of each region based on whether the intra prediction region 33 is included in the synthesis region X determined by the synthesis region determination unit 12. Is configured to change.

For example, as illustrated in FIG. 3A, the intra prediction unit 33, in the area CU#A2 that is not included in the combined area X (that is, the area in which the reference pixels W1 to W3 have been decoded) Y, The intra prediction mode output by the entropy decoding unit 31 is used to generate a predicted image based on the decoded reference pixels W1 to W3.

On the other hand, the intra prediction unit 33, as shown in FIG. 3B, in the area included in the composite area X in CU#A2 (that is, the area in which the reference pixels B2 to B4 have not been decoded) is the above-described value. It is configured to generate a prediction image using a prediction method defined in advance.

The inverse quantization/inverse transform unit 34 performs an inverse quantization process and an inverse transform process (for example, an inverse orthogonal transform process) on the quantized transform coefficient output by the entropy decoding unit 31 to obtain the residual error. It is configured to generate a signal.

The locally decoded image generation unit 35 is configured to generate a locally decoded image by adding the prediction image generated by the intra prediction unit 33 and the residual signal generated by the inverse quantization/inverse transformation unit 34. There is.

The memory unit 36 is configured to hold the locally decoded image generated by the locally decoded image generation unit 35 so that it can be used as a reference image for intra prediction and inter prediction.

FIG. 5 shows a flowchart for explaining an example of an operation of generating a predicted image by the encoding device 1 and the decoding device 3 according to this embodiment.

First, with reference to FIG. 5, an example of an operation of generating a predicted image by the encoding device 1 according to the present embodiment will be described.

As shown in FIG. 5, in step S101, the encoding device 1 determines the optimum intra prediction mode to be applied to the CU.

In step S102, the encoding device 1 determines the synthesis area X in which the predicted image is generated from the undecoded adjacent pixels in the CU, based on the intra prediction mode determined in step S101.

In step S103, the encoding device 1 determines whether or not the area in which the predicted image is generated is included in the synthesis area in the CU. If "No", the operation proceeds to step S104, and if "Yes", the operation proceeds to step S105.

In step S104, the encoding device 1 uses the intra prediction mode determined in step S101 to generate a predicted image based on the decoded reference pixels.

In step S105, the encoding device 1 generates a predicted image by using the above-described predefined prediction method.

Secondly, with reference to FIG. 5, an example of an operation of generating a predicted image by the decoding device 3 according to the present embodiment will be described.

As shown in FIG. 5, in step S101, the decoding device 3 determines the intra prediction mode based on the information obtained by the entropy decoding process.

In step S102, the decoding device 3 determines the synthesis area X in which a predicted image is generated from adjacent pixels that have not been decoded in the CU, based on the intra prediction mode determined in step S101.

In step S103, the decoding device 3 determines whether the area in which the predicted image is generated is included in the synthesis area in the CU. If "No", the operation proceeds to step S104, and if "Yes", the operation proceeds to step S105.

In step S104, the decoding device 3 uses the intra prediction mode determined in step S101 to generate a predicted image based on the decoded reference pixels.

In step S105, the decoding device 3 generates a predicted image by using the above-described predefined prediction method.

According to the encoding device 1 and the decoding device 3 according to the present embodiment, when an undecoded pixel is included in the reference destination in the direction of the intra prediction mode (prediction direction), the adjacent decoded reference pixel is copied. By generating a new predicted image by synthesizing the predicted image generated by using the reference pixel interpolated in step 5 and the predicted image generated by using the predefined prediction method, it is possible to suppress the deterioration of the prediction accuracy. ..

(Second embodiment)
Hereinafter, with reference to FIG. 6, the encoding device 1 and the decoding device 3 according to the second embodiment of the present invention are different from the encoding device 1 and the decoding device 3 according to the above-described first embodiment. The explanation will focus on.

In the encoding device 1 according to the present embodiment, the intra prediction unit 13 determines whether a predetermined condition is satisfied in the boundary area between the area included in the combined area X and the area Y not included in the combined area X. A smoothing filter is applied to the predicted image of the boundary area.

Similarly, in the decoding device 3 according to the present embodiment, when the intra prediction unit 33 satisfies the predetermined condition in the boundary area between the area included in the combined area X and the area Y not included in the combined area X. In addition, the smoothing filter is applied to the predicted image of the boundary area.

For example, in the example of FIG. 6, in the boundary area, pixels X1, X2, X3, X4 in the area included in the combined area X and pixels Y1, Y2, Y3 in the area Y not included in the combined area X are included. The area in which it is located corresponds.

Further, as the predetermined condition, discontinuity in the boundary region may be higher than a predetermined threshold value. Here, as the evaluation of the discontinuity, for example, there is a method of expressing the difference in the horizontal direction, the difference in the vertical direction, the difference in the diagonal direction, and the like by a linear combination.

That is, the intra prediction unit 13 and the intra prediction unit 33 apply the smoothing filter to the predicted image of the boundary region when the value of the evaluation of discontinuity in the boundary region is higher than the predetermined threshold value. It is configured.

For example, in the example of FIG. 6, when the value of the discontinuity evaluation in the boundary area is higher than the predetermined threshold, the intra prediction unit 13 and the intra prediction unit 33 determine the pixels in the area included in the synthesis area X. The smoothing filter is configured to be applied to the predicted image of the area where the pixels Y1, Y2, and Y3 in the area Y not included in the combined area X and X1, X2, X3, and X4 are located.

Note that in the example of FIG. 6, the intra prediction unit 13 and the intra prediction unit 33 apply the smoothing filter also to the predicted image of the region where the pixels X5, X6, and X7 in the region included in the synthesis region X are located. Is configured.

Here, by sharing the above-mentioned predetermined threshold value between the encoding device 1 and the decoding device 3, it is not necessary to transmit a new flag from the encoding device 1 to the decoding device 3.

According to the encoding device 1 and the decoding device 3 according to the present embodiment, the discontinuity of the boundary region caused by changing the method of generating the predicted image of each region based on whether the region is included in the combined region X or not. Can be reduced and the coding performance can be improved.

(Third Embodiment)
Hereinafter, with reference to FIG. 6, regarding the encoding device 1 and the decoding device 3 according to the third embodiment of the present invention, the encoding device 1 and the decoding device 3 according to the above-described first and second embodiments will be described. The description will be made focusing on the difference.

In the encoding device 1 and the decoding device 3 according to the present embodiment, the intra prediction unit 13 and the intra prediction unit 33, in the region included in the synthesis region X, the prediction image generated using the prediction method in the conventional HEVC ( Prediction by a weighted average of a prediction image generated based on an undecoded reference pixel filled by copying) and a prediction image generated in the synthesis area X (a prediction image generated using the above-described predefined prediction method) It is configured to generate an image.

In addition, in the encoding device 1 and the decoding device 3 according to the present embodiment, the intra prediction unit 13 and the intra prediction unit 33 have the conventional intra-prediction unit in the region included in the synthesis region X only when the above-described predetermined condition is satisfied. A prediction image generated by using the prediction method in HEVC (a prediction image generated based on an undecoded reference pixel embedded by copying) and a prediction image generated in the synthesis area X (the above-described predefined prediction method is used). The predicted image may be generated by a weighted average of the predicted image generated by using the predicted image).

In the encoding device 1 and the decoding device 3 according to this embodiment, the intra prediction unit 13 and the intra prediction unit 33 may be configured to calculate the weighting coefficient used when calculating the weighted average.

The intra-prediction unit 13 and the intra-prediction unit 33 may be configured to use a predetermined value as a weighting coefficient, or may use the credibility of the decoded reference pixel at the time of generating the prediction image to weight the weighting coefficient. May be configured to calculate

In the example of FIG. 3B, the decoded reference pixels W1 to W4 have high credibility, and the reference pixels B1 to B4 generated by copying have low credibility. Further, when the credibility of the reference pixel B1 and the credibility of the reference pixel B4 are compared, the credibility of the reference pixel B4 close to the copy source is higher.

Also, the intra prediction unit 13 and the intra prediction unit 33 calculate the weighting factors according to the distance from the boundary region between the region included in the combined region X and the region Y not included in the combined region X. May be configured.

For example, the intra-prediction unit 13 and the intra-prediction unit 33 have a prediction image generated using the prediction method in the conventional HEVC (a prediction generated based on an undecoded reference pixel embedded by copying) near the boundary region. Image), the weighting coefficient of the predicted image generated in the combined region X (the predicted image generated by using the above-described predefined prediction method) is calculated in a region apart from the boundary region. You may calculate so that a coefficient may become strong.

(Other embodiments)
As described above, the present invention has been described by the above-described embodiments, but it should not be understood that the descriptions and drawings forming a part of the disclosure in the embodiments limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

Further, although not particularly mentioned in the above-described embodiment, a program that causes a computer to execute each processing performed by the above-described encoding device 1 and decoding device 3 may be provided. Moreover, such a program may be recorded in a computer-readable medium. Using a computer-readable medium, such a program can be installed in a computer. Here, the computer-readable medium in which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, but may be a recording medium such as a CD-ROM or a DVD-ROM.

Alternatively, a chip configured by a memory that stores a program for realizing at least a part of the functions in the encoding device 1 and the decoding device 3 and a processor that executes the program stored in the memory may be provided. Good.

DESCRIPTION OF SYMBOLS 1... Encoding device 11... Intra prediction mode determination unit 12... Synthesis area determination unit 13... Intra prediction unit 14... Residual signal generation unit 15... Orthogonal transformation/quantization unit 16... Inverse quantization unit/Inverse orthogonal transformation unit 17 Local decoding image generation unit 18 Memory unit 19 Entropy coding unit 3 Decoding device 31 Entropy decoding unit 32 Synthesis area determination unit 33 Intra prediction unit 34 Inverse quantization/inverse conversion unit 35 Local decoding image Generation unit 36... Memory unit

Claims (8)

A coding device configured to divide a frame-based original image forming a moving image into coding target blocks and code the blocks.
Based on the intra prediction modes, determined in the encoding target block, a first region predicted image from the decoded adjacent pixels are generated, and a second region where the predicted image from the adjacent pixels are generated not decoded An area determination unit configured to
A first prediction image is generated for the first region using the intra prediction mode, and a second prediction image is generated for the second region using a prediction method different from the intra prediction mode; An encoding device, comprising: an intra prediction unit configured to generate a new prediction image corresponding to the encoding target block by combining one prediction image and the second prediction image. .. The intra prediction unit smoothes a boundary area between the first predicted image and the second predicted image when a predetermined condition is satisfied in a boundary area between the first area and the second area. Coding device according to claim 1, characterized in that it is arranged to apply a filter. A coding device configured to divide a frame-based original image forming a moving image into coding target blocks and code the blocks.
A first prediction unit that generates a first predicted image by a first prediction process that is determined based on the prediction mode;
A composite area determination unit configured to determine a composite area based on the prediction mode,
A second prediction unit that generates a second predicted image by a second prediction process different from the first prediction process;
A prediction image combination unit that generates a prediction image included in the combination area by a weighted average of the first prediction image and the second prediction image;
The predictive image composition unit determines a weight to be used for the weighted average based on whether a block adjacent to the encoding target block has been decoded or not. A decoding device configured to decode an encoding target block obtained by dividing an original image in frame units forming a moving image,
Based on the intra prediction modes, determined in the encoding target block, a first region predicted image from the decoded adjacent pixels are generated, and a second region where the predicted image from the adjacent pixels are generated not decoded A combination area determination unit configured to
A first prediction image is generated for the first region using the intra prediction mode, and a second prediction image is generated for the second region using a prediction method different from the intra prediction mode; A decoding device, comprising: an intra prediction unit configured to generate a new prediction image corresponding to the encoding target block by synthesizing one prediction image and the second prediction image . The intra prediction unit smoothes a boundary area between the first predicted image and the second predicted image when a predetermined condition is satisfied in a boundary area between the first area and the second area. The decoding device according to claim 4, wherein the decoding device is configured to apply a filter. A decoding device configured to decode an encoding target block obtained by dividing an original image in frame units forming a moving image,
A first prediction unit that generates a first predicted image by a first prediction process that is determined based on the prediction mode;
A composite area determination unit configured to determine a composite area based on the prediction mode,
A second prediction unit that generates a second predicted image by a second prediction process different from the first prediction process;
A prediction image combination unit that generates a prediction image included in the combination area by a weighted average of the first prediction image and the second prediction image;
The decoding device, wherein the predicted image synthesis unit determines a weight to be used for the weighted average based on whether or not a block adjacent to the encoding target block has been decoded. A program for causing a computer to function as the encoding device according to any one of claims 1 to 3. A program for causing a computer to function as the decoding device according to claim 4.

Images