KR101662739B1 - Method and apparatus for encoding and decoding coding unit of picture boundary - Google Patents

Abstract

A method and an apparatus for dividing an image coding unit including an area beyond the boundary of the current picture into smaller coding units and coding only an area that does not deviate from the boundary of the current picture and decoding the image data coded by this coding method A method and apparatus are disclosed.

Description

[0001] The present invention relates to a method and apparatus for encoding and decoding an encoding unit of a picture boundary,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image encoding and decoding method and apparatus, and more particularly, to a method and apparatus for encoding and decoding an image encoding unit of a picture boundary.

In an image compression method such as MPEG-1, MPEG-2, and MPEG-4 H.264 / MPEG-4 Advanced Video coding (AVC), an image is divided into blocks of a predetermined size for encoding. Then, each block is predictively encoded using inter prediction or intra prediction.

SUMMARY OF THE INVENTION The present invention provides a method and apparatus for encoding and decoding an encoding unit of a picture boundary, and a computer-readable recording medium having recorded thereon a program for executing the method.

According to an aspect of the present invention, there is provided a method of encoding an image, the method comprising: determining whether a first coding unit includes an area outside a boundary of a current picture; Dividing a first encoding unit into at least one second encoding unit based on the determination result; And encoding only a second encoding unit that is not out of bounds of the current picture among at least one second encoding unit generated as a result of the division.

According to a further preferred embodiment of the present invention, the information indicating whether the first coding unit is divided is not encoded when the second coding unit which is not outside the boundary of the current picture is coded.

According to a further preferred embodiment of the present invention, the depth of the first encoding unit and the depth of the second encoding unit are different from each other, and the depth of the first encoding unit and the depth of the current encoding unit of the current slice or the current picture, And a degree of stepwise reduction in the second encoding unit.

According to a preferred embodiment of the present invention, the determining step includes determining whether the left or right boundary of the first coding unit is out of the left or right boundary of the current picture.

According to a more preferred embodiment of the present invention, the determining step includes determining whether an upper or lower boundary of the first coding unit is out of an upper or lower boundary of the current picture.

According to an aspect of the present invention, there is provided a method of decoding an image, the method comprising: determining whether a first coding unit includes an area outside a boundary of a current picture; Parsing data for a second encoding unit that is not out of bounds of the current picture among at least one second encoding unit generated by dividing the first encoding unit based on the determination result; And decoding the data for the second encoding unit that does not deviate from the boundary of the current picture.

According to an aspect of the present invention, there is provided an apparatus for encoding an image, the apparatus comprising: a determination unit determining whether a first coding unit includes an area outside a boundary of a current picture; A controller for dividing the first encoding unit into at least one second encoding unit based on the determination result; And an encoding unit encoding only a second encoding unit that is not out of bounds of the current picture among at least one second encoding unit generated as a result of the division.

According to an aspect of the present invention, there is provided an apparatus for decoding an image, the apparatus comprising: a determination unit determining whether a first coding unit includes an area outside a boundary of a current picture; A parsing unit for parsing data for a second encoding unit that is not out of bounds of the current picture among at least one second encoding unit generated by dividing the first encoding unit based on the determination result; And a decoding unit decoding the data for the second encoding unit that does not deviate from the boundary of the current picture.

According to an aspect of the present invention, there is provided a computer-readable recording medium having recorded thereon a program for executing the image encoding method and the image decoding method.

1 illustrates an image encoding apparatus according to an embodiment of the present invention.
FIG. 2 illustrates an image decoding apparatus according to an embodiment of the present invention.
FIG. 3 illustrates a hierarchical encoding unit according to an embodiment of the present invention.
FIG. 4 illustrates an image encoding unit based on an encoding unit according to an embodiment of the present invention.
FIG. 5 illustrates an image decoding unit based on an encoding unit according to an embodiment of the present invention.
FIG. 6 illustrates a maximum encoding unit, a sub-encoding unit, and a prediction unit according to an embodiment of the present invention.
7 shows an encoding unit and a conversion unit according to an embodiment of the present invention.
FIGS. 8A and 8B show a division form of an encoding unit, a prediction unit, and a frequency conversion unit according to an embodiment of the present invention.
9 illustrates an image encoding apparatus according to another embodiment of the present invention.
FIGS. 10A and 10B show coding units of picture boundaries according to an embodiment of the present invention.
11A and 11B illustrate a method of dividing an encoding unit of a picture boundary according to an embodiment of the present invention.
12A and 12B show a picture boundary coding unit and a dividing method according to another embodiment of the present invention.
13A and 13B illustrate an intra prediction method according to an embodiment of the present invention.
FIG. 14 illustrates indexing of a maximum encoding unit according to an embodiment of the present invention.
15 is a flowchart illustrating an image encoding method according to an embodiment of the present invention.
FIG. 16 illustrates still another image decoding apparatus according to an embodiment of the present invention.
17 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.
Figs. 18A to 18G show prediction modes of a first encoding unit of 2Nx2N size including an out-of-bounds area of the current picture.
FIG. 19 is a flowchart illustrating an image encoding method according to another embodiment of the present invention.
20A and 20B are views for explaining a method of encoding a picture unit boundary coding unit according to another embodiment of the present invention.
FIG. 21 is a flowchart illustrating a video decoding method according to another embodiment of the present invention.
22 is a flowchart illustrating a method of encoding an image according to another embodiment of the present invention.
FIGS. 23A and 23B are diagrams for explaining a method of coding a picture unit boundary coding unit according to another embodiment of the present invention.
24 is a flowchart illustrating a video decoding method according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

1 illustrates an image encoding apparatus according to an embodiment of the present invention.

1, an image encoding apparatus 100 according to an exemplary embodiment of the present invention includes a maximum encoding unit division unit 110, an encoding depth determination unit 120, an image data encoding unit 130, (140).

The maximum coding unit division unit 110 may divide the current picture or the current slice based on the maximum coding unit which is the coding unit of the maximum size. The current picture or current slice can be divided into at least one maximum encoding unit.

According to an embodiment of the present invention, an encoding unit can be expressed using a maximum encoding unit and a depth. As described above, the maximum encoding unit indicates the largest encoding unit among the encoding units of the current picture, and the depth indicates the degree to which the encoding units are hierarchically reduced. As the depth increases, the encoding unit can be reduced from the maximum encoding unit to the minimum encoding unit, the depth of the maximum encoding unit can be defined as the minimum depth, and the depth of the minimum encoding unit can be defined as the maximum depth. As the depth of the maximum encoding unit increases, the size of the depth-dependent encoding unit decreases. Therefore, the sub-encoding unit of k depth may include a plurality of sub-encoding units of depth greater than k.

As the size of a picture to be encoded increases, if an image is coded in a larger unit, the image can be encoded with a higher image compression rate. However, if the coding unit is enlarged and its size is fixed, the image can not be efficiently encoded reflecting the characteristics of the continuously changing image.

For example, when coding a flat area with respect to the sea or sky, the compression rate can be improved by increasing the coding unit. However, when coding a complex area for people or buildings, the compression ratio is improved as the coding unit is decreased.

To this end, one embodiment of the present invention sets a maximum image encoding unit of a different size for each picture or slice, and sets a maximum depth. Since the maximum depth means the maximum number of times the encoding unit can be reduced, the minimum encoding unit size included in the maximum image encoding unit can be variably set according to the maximum depth.

The encoding depth determination unit 120 determines the maximum depth. The maximum depth may be determined based on the Rate-Distortion Cost calculation. The maximum depth may be determined differently for each picture or slice, or may be determined differently for each maximum encoding unit. The determined maximum depth is output to the encoding information encoding unit 140, and the image data for each maximum encoding unit is output to the image data encoding unit 130.

The maximum depth means the smallest encoding unit, that is, the minimum encoding unit, which can be included in the maximum encoding unit. In other words, the maximum encoding unit may be divided into sub-encoding units of different sizes according to different depths. Will be described later in detail with reference to Figs. 8A and 8B. In addition, the sub-encoding units of different sizes included in the maximum encoding unit can be predicted or frequency transformed (values of the pixel domain can be transformed into values in the frequency domain, for example, discrete cosine transform) based on processing units of different sizes have. In other words, the image encoding apparatus 100 can perform a plurality of processing steps for image encoding based on various sizes and processing units of various types. In order to encode video data, processing steps such as prediction, frequency conversion, and entropy encoding are performed. Processing units of the same size may be used in all stages, and processing units of different sizes may be used in each step.

For example, in order to predict a predetermined encoding unit, the image encoding device 100 may select a different encoding unit from the encoding unit.

If the size of the encoding unit is 2Nx2N (where N is a positive integer), the processing unit for prediction may be 2Nx2N, 2NxN, Nx2N, NxN, and the like. In other words, motion prediction may be performed based on a processing unit of a type that halves at least one of a height or a width of an encoding unit. Hereinafter, a processing unit serving as a basis of prediction is referred to as a 'prediction unit'.

The prediction mode may be at least one of an intra mode, an inter mode, and a skip mode, and the specific prediction mode may be performed only for a prediction unit of a specific size or type. For example, the intra mode can be performed only for a 2Nx2N, NxN sized prediction unit, which is a square. In addition, the skip mode can be performed only for a prediction unit of 2Nx2N size. If there are a plurality of prediction units in an encoding unit, a prediction mode having the smallest coding error can be selected by performing prediction for each prediction unit.

Also, the image encoding apparatus 100 can frequency-convert image data based on a processing unit having a different size from the encoding unit. The frequency conversion may be performed based on a data unit having a size smaller than or equal to the encoding unit for frequency conversion of the encoding unit. Hereinafter, a processing unit serving as a basis of frequency conversion is referred to as a 'conversion unit'.

The coding depth determiner 120 may determine sub-coding units included in the maximum coding unit using Rate-Distortion Optimization based on a Lagrangian Multiplier. In other words, it is possible to determine what type of sub-encoding unit the maximum encoding unit is divided into, wherein the plurality of sub-encoding units have different sizes depending on the depth. Then, the image data encoding unit 130 encodes the maximum encoding unit based on the division type determined by the encoding depth determination unit 120, and outputs the bit stream.

The encoding information encoding unit 140 encodes information on the encoding mode of the maximum encoding unit determined by the encoding depth determination unit 120. [ Information on the division type of the maximum encoding unit, information on the maximum depth, and information on the encoding mode of the sub-encoding unit by depth, and outputs the bit stream. The information on the encoding mode of the sub-encoding unit may include information on the prediction unit of the sub-encoding unit, prediction mode information per prediction unit, information on the conversion unit of the sub-encoding unit, and the like.

The information on the division type of the maximum encoding unit may be information indicating whether or not the division is performed for each encoding unit. For example, when the maximum encoding unit is divided and encoded, information indicating whether or not the maximum encoding unit is divided is encoded, and even when the sub-encoding unit generated by dividing the maximum encoding unit is divided and coded again, Information indicating whether or not the sub-encoding unit is divided is encoded. The information indicating whether or not to divide may be flag information indicating whether or not to divide.

There is a sub-encoding unit of a different size for each maximum encoding unit, and information on the encoding mode is determined for each sub-encoding unit, so that information on at least one encoding mode can be determined for one maximum encoding unit.

As the depth increases, the image encoding apparatus 100 may generate a sub-encoding unit by dividing the maximum encoding unit by half the height and the width. That is, if the size of the encoding unit of the kth depth is 2Nx2N, the size of the encoding unit of the k + 1th depth is NxN.

Accordingly, the image encoding apparatus 100 according to an exemplary embodiment can determine an optimal division type for each maximum encoding unit based on the size and the maximum depth of a maximum encoding unit considering characteristics of an image. It is possible to more efficiently encode images of various resolutions by adjusting the size of the maximum encoding unit in consideration of the image characteristics and encoding the image by dividing the maximum encoding unit into sub-encoding units of different depths.

FIG. 2 illustrates an image decoding apparatus according to an embodiment of the present invention.

2, an image decoding apparatus 200 according to an exemplary embodiment of the present invention includes an image data obtaining unit 210, an encoding information extracting unit 220, and an image data decoding unit 230.

The image-related data acquisition unit 210 parses the bit stream received by the image decoding apparatus 200, acquires image data for each maximum encoding unit, and outputs the image data to the image data decoding unit 230. The image data obtaining unit 210 may extract information on the maximum coding unit of the current picture or slice from the header of the current picture or slice. In other words, the bitstream is divided into a maximum encoding unit, and the video data decoding unit 230 decodes the video data per maximum encoding unit.

The encoding information extracting unit 220 parses the bit stream received by the video decoding apparatus 200 and extracts a maximum encoding unit, a maximum depth, a division type of the maximum encoding unit, and a coding mode of the sub-encoding unit from the header for the current picture . The information on the division type and the encoding mode is output to the video data decoding unit 230. [

The information on the division type of the maximum encoding unit may include information on the sub-encoding units of different sizes depending on the depth included in the maximum encoding unit. As described above, the information on the division type may be information (e.g., flag information) indicating whether or not the division is coded for each coding unit.

The information on the encoding mode may include information on a prediction unit for each sub-encoding unit, information on a prediction mode, and information on a conversion unit.

The image data decoding unit 230 decodes the image data of each maximum encoding unit based on the information extracted by the encoding information extracting unit to restore the current picture.

The image data decoding unit 230 can decode the sub-encoding unit included in the maximum encoding unit based on the information on the division type of the maximum encoding unit. The decoding process may include a motion prediction process including intra prediction and motion compensation, and an inverse frequency conversion process.

The image data decoding unit 230 may perform intra prediction or inter prediction based on information on a prediction unit for each sub-coding unit and prediction mode information for prediction of a sub-coding unit. In addition, the image data decoding unit 230 can perform frequency inverse transform for each sub-encoding unit on the basis of the information on the conversion unit of the sub-encoding unit.

FIG. 3 illustrates a hierarchical encoding unit according to an embodiment of the present invention.

Referring to FIG. 3, the hierarchical coding unit according to the present invention may include 32x32, 16x16, 8x8, and 4x4 from a coding unit having a width x height of 64x64. In addition to the square-shaped encoding units, there may be encoding units whose width x height is 64x32, 32x64, 32x16, 16x32, 16x8, 8x16, 8x4, 4x8.

Referring to FIG. 3, the maximum encoding unit size is set to 64x64 and the maximum depth is set to 2 for the image data 310 having a resolution of 1920x1080.

The size of the maximum encoding unit is set to 64x64 and the maximum depth is set to 4 for the image data 320 having another resolution of 1920x1080. For the video data 330 having a resolution of 352x288, the size of the maximum encoding unit is set to 16x16 and the maximum depth is set to 2. [

It is desirable that the maximum size of the encoding size is relatively large in order to accurately reflect not only the compression ratio but also the image characteristic when the resolution is high or the data amount is large. Therefore, the size of the maximum encoding unit of the image data 310 and 320 having a higher resolution than the image data 330 can be selected to be 64x64.

The maximum depth indicates the total number of layers in the hierarchical encoding unit. Since the maximum depth of the image data 310 is 2, the coding unit 315 of the image data 310 is divided into sub-coding units 315 having a major axis size of 32 and 16 as the depth increases, .

On the other hand, since the maximum depth of the image data 330 is 2, the encoding unit 335 of the image data 330 is encoded from the maximum encoding units having the major axis size of 16 to the encoding units having the major axis size of 8 and 4 Units.

Since the maximum depth of the video data 320 is 4, the encoding unit 325 of the video data 320 has a length of 32, 16, 8, and 4 as the depth increases, Sub-encoding units. As the depth increases, the image is encoded based on a smaller sub-encoding unit, which makes it suitable for encoding an image including a finer scene.

FIG. 4 illustrates an image encoding unit based on an encoding unit according to an embodiment of the present invention.

The intra prediction unit 410 performs intra prediction on a prediction unit of the intra mode of the current frame 405 and the motion estimation unit 420 and the motion compensation unit 425 perform intra prediction on the prediction unit of the intra mode, 405 and a reference frame 495. The inter-prediction and the motion compensation are performed using the reference frame 495 and inter-prediction.

The residual values are generated based on the prediction unit output from the intra prediction unit 410, the motion estimation unit 420 and the motion compensation unit 425, and the generated residual values are input to the frequency conversion unit 430 and the quantization unit 420. [ (440) and output as quantized transform coefficients.

The quantized transform coefficients are restored to a residual value through the inverse quantization unit 460 and the frequency inverse transform unit 470. The restored residual values are passed through the deblocking unit 480 and the loop filtering unit 490, And output to the reference frame 495. [ The quantized transform coefficient may be output to the bitstream 455 via the entropy encoding unit 450.

In order to perform encoding according to the image encoding method according to an embodiment of the present invention, an intra prediction unit 410, a motion estimation unit 420, a motion compensation unit 425, The inverse quantization unit 460, the inverse quantization unit 470, the deblocking unit 480 and the loop filtering unit 490 of the quantization unit 430, the quantization unit 440, the entropy coding unit 450, the inverse quantization unit 460, , Sub-encoding units according to depth, prediction units, and conversion units.

FIG. 5 illustrates an image decoding unit based on an encoding unit according to an embodiment of the present invention.

The bitstream 505 passes through the parser 510 and the encoded image data to be decoded and the encoding information necessary for decoding are parsed. The encoded image data is output as inverse-quantized data through the entropy decoding unit 520 and the inverse quantization unit 530, and is restored to the residual values through the frequency inverse transform unit 540. [ The residual values are added to the intraprediction result of the intraprediction unit 550 or the motion compensation result of the motion compensation unit 560, and restored for each encoding unit. The reconstructed coding unit is used for predicting the next coding unit or the next picture through the deblocking unit 570 and the loop filtering unit 580.

A parsing unit 510, an entropy decoding unit 520, an inverse quantization unit 530, an inverse frequency transforming unit (hereinafter referred to as an inverse quantization unit) 530, The intra prediction unit 550, the motion compensation unit 560, the deblocking unit 570 and the loop filtering unit 580 are all based on the maximum encoding unit, the depth-dependent sub-encoding unit, the prediction unit, And processes the image decoding processes.

In particular, the intra prediction unit 550 and the motion compensation unit 560 determine a prediction unit and a prediction mode in the sub-coding unit in consideration of the maximum coding unit and the depth, and the frequency inverse transform unit 540 considers the size of the conversion unit Thereby performing frequency inverse transform.

FIG. 6 illustrates a maximum encoding unit, a sub-encoding unit, and a prediction unit according to an embodiment of the present invention.

The image encoding apparatus 100 and the image decoding apparatus 200 according to an embodiment of the present invention use a hierarchical encoding unit to perform encoding and decoding in consideration of image characteristics. The maximum encoding unit and the maximum depth may be adaptively set according to the characteristics of the image, or may be variously set according to the demand of the user.

The hierarchical structure 600 of the encoding unit according to an embodiment of the present invention shows a case where the height and the width of the maximum encoding unit 610 are 64 and the maximum depth is 4. The depth increases along the vertical axis of the hierarchical structure 600 of the encoding unit, and the height and width of the sub-encoding units 620 to 650 decrease as the depth increases. Prediction units of the maximum encoding unit 610 and the sub-encoding units 620 to 650 are shown along the horizontal axis of the hierarchical structure 600 of the encoding units.

The maximum encoding unit 610 has a depth of 0, and the size of the encoding unit, i.e., the height and the width, is 64x64. A sub-encoding unit 620 having a depth 1 of 32x32 and a sub-encoding unit 630 having a depth 16x16 having a depth of 16x16, a sub-encoding unit 640 having a depth of 3x8 having a size 8x8, There is a sub-encoding unit 650 of depth 4. A sub-encoding unit 650 of depth 4 with a size of 4x4 is the minimum encoding unit.

Referring to FIG. 6, examples of prediction units along the horizontal axis are shown for each depth. That is, the prediction unit of the maximum coding unit 610 of depth 0 is a prediction unit 610 of size 64x64, a prediction unit 612 of size 64x32, and size 32x64, which are the same or smaller than the coding unit 610 of size 64x64, A prediction unit 614 of size 32x32, and a prediction unit 616 of size 32x32.

The prediction unit of the 32x32 coding unit 620 having the depth 1 has the prediction unit 620 of the size 32x32 which is equal to or smaller than the coding unit 620 of the size 32x32, the prediction unit 622 of the size 32x16, A prediction unit 624 of size 16x16, and a prediction unit 626 of size 16x16.

The prediction unit of the 16x16 encoding unit 630 of depth 2 has a prediction unit 630 of 16x16 size, a prediction unit 632 of size 16x8, and a size of 8x16, which are the same or smaller than the encoding unit 630 of size 16x16. A prediction unit 634 of size 8x8, and a prediction unit 636 of size 8x8.

The prediction unit of the 8x8 encoding unit 640 of depth 3 has a prediction unit 640 of size 8x8, a prediction unit 642 of size 8x4, and a size of 4x8, which are the same or smaller than the encoding unit 640 of size 8x8. A prediction unit 644 of size 4x4, and a prediction unit 646 of size 4x4.

Finally, the coding unit 650 of size 4x4 is the minimum coding unit and the coding unit of maximum depth, and the prediction unit is the prediction unit 650 of size 4x4.

7 shows an encoding unit and a conversion unit according to an embodiment of the present invention.

The image encoding apparatus 100 and the image decoding apparatus 200 according to an embodiment of the present invention encode the maximum encoding unit as a unit or encode the maximum encoding unit in units of sub encoding units smaller than or equal to the maximum encoding unit. The size of a conversion unit for frequency conversion during encoding is selected as a conversion unit that is not larger than each encoding unit. For example, when the current encoding unit 710 is 64x64, the frequency conversion can be performed using the 32x32 conversion unit 720. [

FIGS. 8A and 8B show a division form of an encoding unit, a prediction unit, and a frequency conversion unit according to an embodiment of the present invention.

8A shows an encoding unit and a prediction unit according to an embodiment of the present invention.

The left side of FIG. 8A shows a division type selected by the image encoding apparatus 100 according to an embodiment of the present invention to encode the maximum encoding unit 810. The image encoding apparatus 100 divides the maximum encoding unit 810 into various types, encodes the encoded image, and then selects an optimal division type by comparing the encoding results of various division types based on the R-D cost. When it is optimal to directly encode the maximum encoding unit 810, the maximum encoding unit 800 may be encoded without dividing the maximum encoding unit 810 as shown in FIGS. 8A and 8B.

Referring to the left side of FIG. 8A, a maximum encoding unit 810 having a depth of 0 is divided into sub-encoding units having a depth of 1 or more and encoded. The maximum encoding unit 810 is divided into sub-encoding units of four depths 1, and then all or a part of the sub-encoding units of depth 1 are divided into sub-encoding units of depth 2 again.

Among the sub-coding units of depth 1, sub-coding units coded at the upper right and sub-coding units located at the lower left are divided into sub-coding units of depth 2 or more. Some of the sub-encoding units having depths of 2 or more may be further divided into sub-encoding units having depths of 3 or more.

The right side of FIG. 8B shows the division type of the prediction unit for the maximum coding unit 810.

Referring to the right side of FIG. 8A, the prediction unit 860 for the maximum coding unit can be divided into the maximum coding unit 810 and the prediction unit 860 for the maximum coding unit. In other words, the prediction unit for each of the sub-encoding units may be smaller than the sub-encoding unit.

For example, a prediction unit for a sub-coding unit 854 coded right below the sub-coding unit at depth 1 may be smaller than the sub-coding unit 854. The prediction unit for some of the sub-encoding units 815, 816, 850, and 852 among the sub-encoding units 814, 816, 818, 828, 850, and 852 at the depth 2 may be smaller than the sub-

In addition, the prediction unit for the sub-coding units 822, 832, and 848 of depth 3 may be smaller than the sub-coding unit. The prediction unit may be a form in which each sub-coding unit is halved in the height or width direction, or may be divided into four in height and width directions.

FIG. 8B shows a prediction unit and a conversion unit according to an embodiment of the present invention.

The left side of FIG. 8B shows the division form of the prediction unit for the maximum coding unit 810 shown on the right side of FIG. 8A, and the right side of FIG. 8B shows the division form of the conversion unit of the maximum coding unit 810.

Referring to the right side of FIG. 8B, the division type of the conversion unit 870 may be set differently from the prediction unit 860. [

For example, even if the prediction unit for the depth 1 encoding unit 854 is selected to be half the height, the conversion unit may be selected to be the same size as the depth unit 854 encoding unit. Likewise, even if the prediction unit for the depth 2 coding units 814 and 850 is selected in such a manner that the height of the depth level 2 coding units 814 and 850 is halved, the level of the level 2 coding units 814 and 850 It can be selected to be the same size as the original size.

The conversion unit may be selected to be smaller than the prediction unit. For example, if the prediction unit for depth 2 coding unit 852 is chosen to be half the width, the conversion unit may be selected to be half the width and height, which is a smaller size than the prediction unit.

9 illustrates an image encoding apparatus according to another embodiment of the present invention.

9, an image encoding apparatus 900 according to an exemplary embodiment of the present invention includes a determination unit 910, a control unit 920, and an encoding unit 930. Referring to FIG. The image encoding apparatus 900 may be an apparatus for encoding an image based on an encoding unit, a prediction unit, and a conversion unit that are gradually changed in size according to the depth described above.

The determination unit 910 determines whether the first encoding unit input to the image encoding apparatus 900 for encoding includes an area outside the boundary of the current picture.

If the first encoding unit does not include an area outside the boundary of the current picture, the image encoding device 900 codes the first encoding unit as it is. The first encoding unit may be predicted and not subjected to frequency division (for example, discrete cosine transform), and the first encoding unit may be divided into a predetermined depth as described above with reference to FIGS. 2, 6, 8A, And then frequency conversion may be performed.

However, if the first encoding unit includes an area outside the boundary of the current picture, the first encoding unit is divided to generate at least one second encoding unit, and then only the second encoding unit that does not deviate from the boundary of the current picture .

In other words, the image encoding apparatus 900 encodes the first encoding unit using a different encoding method depending on whether the first encoding unit includes an area outside the boundary of the current picture, and the determination unit 910 encodes the first encoding unit 1 < / RTI > coding unit includes an area outside the boundary of the current picture. Will be described later with reference to Figs. 10A and 10B.

FIGS. 10A and 10B show coding units of picture boundaries according to an embodiment of the present invention.

Referring to FIGS. 10A and 10B, the first coding unit 1020 spans the boundary 1010 of the current picture. If the size of the current picture is not a multiple of the size of the maximum encoding unit, for example, the size of the maximum encoding unit is set to 32x32 to encode the current picture. If the size of the current picture is not a multiple of 32 The maximum encoding unit may include an area 1024 outside the boundary 1010 of the current picture. Similarly, as shown in FIG. 10B, the first coding unit 1040 may include an area 1044 outside the boundary 1030 of the current picture. In FIG. 10A, the left side of the boundary 1010 of the current picture is the inner area of the current picture, the right side is the outer area of the current picture, the upper part of the boundary 1030 of the current picture is the inner area of the current picture, Is the outer area of the current picture.

10A and 10B show a case where the first coding unit 1020 or 1040 spans the right boundary and the lower boundary of the current picture. However, when the first coding unit 1020 or 1040 is located at the left boundary and the upper boundary of the current picture There may be cases in which it is spread.

10A and 10B, the determination unit 910 determines whether or not the first coding unit 1020 or 1040 includes an area outside the boundary 1010 or 1030 of the current picture, (1020 or 1040) with the boundary of the current picture.

If the right boundary of the first coding unit 1020 is out of the right boundary of the current picture or the left boundary is out of the left boundary of the current picture, the first coding unit 1020 is located outside the boundary 1010 of the current picture As shown in FIG. If the lower boundary of the first coding unit 1040 is out of the lower boundary of the current picture or the upper boundary is out of the upper boundary of the current picture, then the first coding unit 1040 is positioned at the boundary 1030 of the current picture It can be judged that it includes an area deviated from the center.

9, when the determination unit 910 determines that the first coding unit 1020 or 1040 includes an area outside the boundary of the current picture, the controller 920 determines whether the first coding unit 1020 or 1040 1040) into at least one second encoding unit.

The image encoding apparatus 900 according to an embodiment of the present invention can encode and decode an image using the hierarchical encoding unit. The maximum encoding unit can be divided into sub-encoding units having a predetermined depth to encode and decode an image. At this time, the depth indicates the degree of stepwise reduction from the maximum encoding unit to the predetermined sub-encoding unit.

The controller 920 divides the first coding unit 1020 into at least one second coding unit according to the depth. For example, if the first encoding unit 1020 is the maximum encoding unit of depth 0, the first encoding unit 1020 can be divided into at least one depth 1 encoding unit. In addition, the first encoding unit 1020 may be divided into an encoding unit having a depth greater than that of the depth 1, i.e., an encoding unit having a depth of 2 or more. Will be described in detail with reference to Figs. 11A and 11B.

11A and 11B illustrate a method of dividing an encoding unit of a picture boundary according to an embodiment of the present invention.

11A shows a case where the first coding unit 1020 shown in FIG. 10A is divided into at least one second coding unit 1110 to 1140. FIG. As described above with reference to FIG. 10A, when the first coding unit 1020 extends over the picture boundary, the first coding unit 1020 includes an area 1024 that is out of bounds of the current picture.

The first coding unit 1020 is divided into at least one second coding unit 1110 to 1140 having different depths to divide the second coding units 1110 to 1120 and the boundary between the current picture 1110 and 1120, And the second encoding unit 1130 to 1140 for the area out of the second encoding unit.

FIG. 11B shows a case where the first coding unit 1040 shown in FIG. 10B is divided into at least one second coding unit 1150 to 1180.

The first coding unit 1040 is divided into at least one second coding unit 1150 to 1180 having different depths so that the second coding units 1150 to 1160 and the boundary between the current picture and the current picture And second encoding units 1170 to 1180 for an area outside the frame.

11A and 11B illustrate a case where the first encoding unit 1020 or 1040 is divided into four second encoding units of the same size and the second encoding unit for an area which is not out of bounds and the second encoding unit Can be distinguished from each other. However, even if the first encoding unit 1020 or 1040 is divided into four second encoding units of the same size, the second encoding unit for the region that does not deviate from the boundary and the second encoding unit for the region outside the border are classified There is a case that can not be. Will be described in detail with reference to Figs. 12A and 12B.

12A and 12B show a picture boundary coding unit and a dividing method according to another embodiment of the present invention.

12A, when the first coding unit 1220 is located at the picture boundary, even if the first coding unit 1220 is divided into the second coding units 1230 to 1260, 2 encoding unit and a second encoding unit that does not deviate from the boundary can not be distinguished. Since some of the second encoding units 1250 and 1260 still include an out-of-bounds region and an out-of-bounds region.

Therefore, the dividing unit repeatedly divides the first encoding unit 1220 when the first encoding unit 1220 is located at the boundary, as shown in FIG. 12A. In the embodiment shown in FIG. 12A, the second encoding units 1250 and 1260 are further divided to generate the third encoding units 1252 to 1258 and 1262 to 1268.

By dividing the second encoding units 1250 and 1260 into a third encoding unit of smaller size, encoding units 1230, 1240, 1252, 1254, 1262 and 1264 that are not out of bounds and encoding units 1256, 1258, 1266 and 1268).

Referring again to FIG. 9, the controller 920 divides the first encoding unit 1020, 1040, or 1220 as shown in FIGS. 11A, 11B, and 12B to divide an area out of bounds and an area not out of bounds , The encoding unit 930 encodes only an encoding unit that does not deviate from the boundary of the current picture among at least one encoding unit generated by dividing the first encoding unit.

If the first coding unit does not include a region out of bounds of the current picture, the first coding unit is entirely coded. The first encoding unit may be predicted and not subjected to frequency division (for example, discrete cosine transform), and the first encoding unit may be divided into a predetermined depth as described above with reference to FIGS. 2, 6, 8A, And then frequency conversion may be performed.

However, if the first encoding unit includes an area outside the boundary of the current picture, only the pixel values of the area that does not deviate from the boundary are encoded according to the division result of the controller 920.

In the embodiment shown in FIG. 11A, the second encoding units 1110 and 1120 located on the left side are encoded, and the second encoding units 1150 and 1160 located on the upper side in the embodiment shown in FIG. 11B are encoded. In the example shown in FIG. 12B, the second coding units 1230 and 1240 located on the left side and the third coding units 1252, 1254, 1262 and 1264 located on the left side are coded. Predicts encoding units that are not out of bounds based on a predetermined prediction unit, and frequency-converts the residual values generated as a result of prediction, based on a predetermined conversion unit.

Since the image encoding apparatus 900 according to an embodiment of the present invention can encode only pixel values that are not out of bounds among the first encoding units located at the picture boundary, it is possible to prevent the compression rate from being lowered due to encoding of unnecessary pixel values out of bounds can do.

In addition, information on the above-described division of the encoding unit 930 (e.g., flag information indicating whether or not to divide) can be selectively encoded. If the first coding unit spans the picture boundary, the first coding unit is divided by the control unit 920. Since division is essential to encode only pixel values of an area that does not deviate from the boundary, it is not necessary to encode information about division in the first encoding unit. This is because it is possible to know that the first encoding unit is divided on the decoding side even if the information on division is not separately encoded.

However, since the encoding unit 930 does not encode the pixel values of the area outside the boundary of the current picture according to the above-described image encoding method, if the first encoding unit spanning the boundary can not be used for prediction of another encoding unit May occur. Will be described in detail with reference to Figs. 13A and 13B.

13A and 13B illustrate an intra prediction method according to an embodiment of the present invention.

Referring to FIG. 13A, an intra prediction method according to an embodiment of the present invention may use previously coded neighboring pixel values 1320 in intra-prediction of a predetermined prediction unit 1310. FIG. In particular, the intra prediction according to an embodiment of the present invention may further use pixels of the 'PuSize' in the lower left direction of the prediction unit 1310.

The image encoding method according to the present invention encodes an image using a hierarchical encoding unit as shown in FIG. 8A. Accordingly, intraprediction can be performed using pixels adjacent to the left and lower left of the prediction unit 1310 as well. For example, when intraprediction of the coding unit 830 of FIG. 8A is performed, pixels included in the upper and right upper parts of the coding unit 830, that is, the pixels included in the coding unit 812, It is possible to perform intra prediction using pixels adjacent to the left and lower left sides, that is, pixels included in the coding unit 828. [

However, there may be cases where pixels adjacent to the upper right and lower left are not available. When encoding the encoding unit 1330 as shown in FIG. 13B, some pixel values 1346 of the pixel values adjacent to the upper right can not be used. The coding unit 1344 in the area outside the boundary 1350 of the current picture is not coded when coding the coding unit 1340 located in the upper right corner. Thus, adjacent pixels that are available for intra prediction of the encoding unit 1330 are only the upper, left and lower left pixels.

The encoding unit 130 determines whether 'cux + cuSize + cuSize' is larger than the above-described 'Frame_width' in order to determine whether or not pixels adjacent to the upper right portion can be used. 'cux' is the X coordinate of the left boundary of the coding unit 1330, 'cuSize' is the horizontal and vertical size of the coding unit 1330, and 'Frame_width' is the horizontal size of the defective picture.

In addition, the encoding unit 130 determines whether 'cuy + cuSize + cuSize' is larger than 'Frame_height' in order to determine whether or not the pixels adjacent to the lower left corner can be used. 'cux' is the X coordinate of the left boundary of the coding unit 1330, 'cuSize' is the horizontal and vertical size of the coding unit 1330, and 'Frame_height' is the vertical size of the current picture.

The encoding unit 130 can more efficiently encode information on the encoding method, that is, information on the encoding mode, based on whether the first encoding unit includes an out-of-bound area. If the first encoding unit includes an out-of-bounds region, information on the encoding mode may be encoded so that the first encoding mode is a second encoding mode, which is another encoding mode.

18A to 18G, information on the prediction mode of the first coding unit is coded as an example.

18A to 18G show prediction modes of a first encoding unit of 2Nx2N size including an out-of-bounds area of a current picture. In Figs. 18A to 18H, the hatched area is an area outside the boundary of the current picture.

Referring to FIG. 18A, the Nx2N area on the right side of the first encoding unit of 2Nx2N is an area outside the boundary. In encoding the first encoding unit of FIG. 18A, the encoding unit 930 performs prediction in the Nx2N prediction mode because the region outside the boundary does not perform prediction even if the prediction mode is selected to be 2Nx2N.

In other words, even when the encoding unit 930 sets the information on the prediction mode of the first encoding unit to the 2Nx2N prediction mode, the prediction is performed in the same manner as when the encoding unit 930 is set to the Nx2N prediction mode. Therefore, there is no need to separately set the Nx2N prediction mode, and information on the 2Nx2N prediction mode can be used as information on the Nx2N prediction mode. This is the same as the effect of reducing the type of the prediction mode, and accordingly, the number of bits required for encoding the information on the prediction mode by the encoding unit 930 can be reduced.

Similarly, in FIG. 18B, the encoding unit 930 can replace the 2NxN prediction mode by setting the prediction mode of the first encoding unit to the 2Nx2N prediction mode.

In FIG. 18C, the encoding unit 930 can replace the 2NxN / 2 prediction mode by setting the prediction mode of the first encoding unit to the 2Nx2N prediction mode. Compared with FIG. 18B, the vertical size of the predicted area is reduced to 1/2 in FIG. 18C. However, since prediction of only an area not deviated from the boundary in the first coding unit is the same as that of FIG. 18B, the 2NxN / 2 prediction mode can be substituted for the 2Nx2N prediction mode by setting the prediction mode of the first coding unit to 2Nx2N prediction mode.

In FIG. 18D, the encoding unit 930 can replace the 2NxN prediction mode by setting the prediction mode of the first encoding unit to the NxN prediction mode. If the first encoding unit in FIG. 18D is predicted to be in the 2NxN prediction mode and the right half of the first encoding unit is included in the out-of-bounds region, the prediction is performed in the NxN size as in the NxN prediction mode. Therefore, the 2NxN prediction mode can be substituted for the NxN prediction mode.

In FIG. 18E, the encoding unit 930 can replace the 2NxN / 2 prediction mode by setting the prediction mode of the first encoding unit to the 2NxN prediction mode. Compared with FIG. 18B, prediction is performed based on two prediction units whose vertical size is reduced to 1/2. Therefore, in the 2Nx2N prediction mode set according to FIG. 18B, the prediction mode of the first encoding unit can be set to the 2NxN prediction mode in which only the portion of the vertical size is reduced to 1/2.

In FIG. 18F, the encoding unit 930 can replace the NxN prediction mode by setting the prediction mode of the first encoding unit to the 2Nx2N prediction mode. The first coding unit in Fig. 18F predicts only the area not deviated from the boundary in the first coding unit as in Figs. 18A, 18B and 18C. Therefore, the prediction mode of the first encoding unit can be set to the 2Nx2N prediction mode to replace the NxN prediction mode.

In FIG. 18G, the encoding unit 930 can replace the N / 2xN prediction mode by setting the prediction mode of the first encoding unit to the Nx2N prediction mode. Compared with FIG. 18F, prediction is performed based on two prediction units whose horizontal size is reduced to 1/2. Therefore, the prediction mode of the first encoding unit can be set to the Nx2N prediction mode in which the horizontal part is reduced to 1/2 in the 2Nx2N prediction mode set according to FIG. 18B.

The encoding process of the image encoding apparatus 900 described above with reference to FIGS. 9 to 13 can be implemented by the following programming codes.

UInt uiLPelX

UInt uiRPelX

UInt uiTPelY

UInt uiBPelY

getSlice () -> getWidth ()) && (uiBPelY <pcCU-> getSlice () -> getHeight ())))

{

   go_next_depth_process ();

}

Referring to the programming code, a left X coordinate, a right X coordinate, an upper Y coordinate, and a lower Y coordinate of the first coding unit are calculated using the functions 'UInt uiLPeLX', 'UInt uiRPeLX', 'UInt uiTPeLY', and 'UInt uiBPeLY' And get the horizontal size of the current picture and the vertical size of the current picture using 'pcCU-> getSlice () -> getWidth ()' and 'uiBPelY <pcCU-> getSlice () -> getHeight ()'.

Then, the left X coordinate of the first coding unit is compared with the horizontal size of the current picture, and the lower Y coordinate of the first coding unit is compared with the vertical size of the current picture. If the left X coordinate of the first coding unit is larger than the horizontal size of the current picture or the lower Y coordinate of the first coding unit is larger than the vertical size, the 'go_next_depth_process ()' function is called to set the next depth, The first encoding unit is divided into a second encoding unit of depth 'k + 1' that is greater than depth 'k', and only the second encoding unit that is not out of bounds of the current picture is encoded.

However, even when the image encoding apparatus 900 encodes only an area not deviated from the boundary of the current picture as shown in FIGS. 9 to 13, the address of the maximum encoding unit is set assuming that an area outside the boundary is also coded . Will be described in detail with reference to FIG.

FIG. 14 illustrates indexing of a maximum encoding unit according to an embodiment of the present invention.

Referring to FIG. 14, when the current picture 1410 is divided into a maximum coding unit of a predetermined size and coded, if the width 'Frame_width' and height 'Frame_height' of the current picture are not a multiple of the horizontal size of the maximum coding unit, The maximum coding units are spread over the right boundary and the lower boundary of the current picture 1310 as shown in FIG.

9 to 13, the image encoding apparatus 900 of the present invention encodes the maximum encoding unit spanning the boundary, and encodes only the region not exceeding the boundary of the current picture. However, when setting the address of the maximum encoding unit, the address of the maximum encoding unit is set based on 'Frame_widthN' and 'Frame_heightN' instead of 'Frame_width' and 'Frame_height'. In other words, an address is added to the maximum encoding unit that spans the right boundary and the lower boundary of the current picture to set the address of the maximum encoding unit.

For example, the largest coding unit located at the rightmost position of the first row is located at the right border of the current picture, and only the region not bounded by the boundary is coded, but the address is added with 'P' The address of the maximum encoding unit located is 'P + 1'. 'Frame_widthN' and 'Frame_heightN' can be calculated as follows.

If Frame_width% LcuSize not equal to 0,

  Frame_widthN = (Frame_width / LcuSize + 1) * LcuSize

If Frame_height% LcuSize not equal to 0,

Frame_heightN = (Frame_height / LcuSize + 1) * LcuSize

'Frame_width% LcuSize' means a remainder obtained by dividing 'Frame_width' by 'LcuSize', and 'Frame_height% LcuSize' means a remainder obtained by dividing 'Frame_height' by 'LcuSize'. 'Frame_width / LcuSize' means a quotient obtained by dividing 'Frame_width' by 'LcuSize', and 'Frame_height / LcuSize' means a quotient obtained by dividing 'Frame_height' by 'LcuSize'. 'LcuSize' means the width and height of the largest encoding unit when the maximum encoding unit is square.

15 is a flowchart illustrating an image encoding method according to an embodiment of the present invention.

Referring to FIG. 15, in step 1510, the image encoding apparatus 900 determines whether the first encoding unit includes an area outside the boundary of the current picture. 10A, 10B and 12A, it is determined whether or not the first coding unit spans the picture boundary and includes an area outside the boundary. The boundary of the current picture and the boundary of the first encoding unit are compared with each other to determine whether the boundary includes an area outside the boundary. It is determined whether the left or right boundary of the first coding unit is out of the left or right boundary of the current picture or whether the upper or lower boundary of the first coding unit is out of the upper or lower boundary of the current picture.

In operation 1520, the image encoding apparatus 900 divides the first encoding unit into at least one second encoding unit based on the determination result in operation 1510. The first encoding unit can be divided into a second encoding unit of depth 'k + 1' that is larger than the depth 'k' of the first encoding unit. If it is determined that the second coding unit further includes the area out of the picture boundary, the decoding is repeated until the coding unit generated as a result of division does not include the area outside the picture boundary. Divide one encoding unit.

In step 1530, the image encoding apparatus 900 selectively encodes only the second encoding unit that does not deviate from the picture boundary among the at least one second encoding unit generated as a result of the division in step 1520. Predicts the second encoding unit, generates residual values, and frequency transforms, quantizes, and entropy-encodes the generated residual values. Also, since the image coding apparatus 900 is required to divide the first coding unit spanning the picture boundary, information indicating whether or not to divide the first coding unit may not be coded.

In addition, as described above with reference to FIGS. 18A to 18G, the image encoding apparatus 900 can encode information on the encoding mode based on whether the first encoding unit includes an out-of-bounds region.

FIG. 16 illustrates still another image decoding apparatus according to an embodiment of the present invention.

16, an image decoding apparatus 1600 according to an exemplary embodiment of the present invention includes a determination unit 1610, a parser 1610, and a decoding unit 1620.

The determination unit 1610 determines whether the first encoding unit to be decoded includes an area outside the boundary of the current picture. It can be determined whether the first encoding unit to be decoded based on the previously decoded encoding unit is an area outside the boundary of the current picture. For example, in the embodiment shown in FIG. 14, when the immediately previous encoding unit is a 'P-1' encoding unit, the first encoding unit to be decoded covers the boundary of the current picture, As shown in FIG.

In other words, it is determined whether the left or right boundary of the first coding unit to be currently decoded is out of the left or right boundary of the current picture or whether the upper or lower boundary of the first coding unit is out of the upper or lower boundary of the current picture And judges whether the first coding unit to be decoded is over the boundary of the current picture.

The parsing unit 1610 receives an image bitstream and, if it is determined that the first encoding unit includes an area out of bounds of the current picture, converts the picture of at least one second encoding unit generated by dividing the first encoding unit And parses only the data for the second encoding unit that is not out of bounds. The depth of the second encoding unit may be the encoding unit of the depth 'k + 1' which is larger than the depth 'k' of the first encoding unit. Also, if it is determined that the first encoding unit does not include a region outside the picture boundary, all of the data for the first encoding unit is parsed.

When parsing only the data of the second encoding unit that is not out of the picture boundary and the first encoding unit is judged to include an area outside the picture boundary, information on whether or not the first encoding unit is divided (for example, Information) may not be parsed. It is necessary to divide the first coding unit spanning the picture boundary. If information on division is not coded, there is no information to be parsed. However, even if information on division is coded, .

In addition, even when information on division is parsed, only the second coding unit generated by dividing the first coding unit is parsed for only the second coding unit that does not deviate from the picture boundary.

The decoding unit 1630 decodes the data in the second encoding unit that is not out of bounds of the current picture parsed by the parsing unit 1620. Reconstructs residual values by entropy decoding, inverse quantization, and inverse frequency transform (e.g., inverse discrete cosine transform) on the data of the second encoding unit that is not out of bounds, and generates the second encoding unit by intra or inter prediction And restores the second encoding unit by adding the predicted value and the restored residual values.

The method of setting the address of the encoding unit used for decoding is the same as that shown in FIG. 14, and neighboring pixels that can be used for intra prediction in the decoding process are as shown in FIGS. 13A and 13B.

The information on the encoding mode of the first encoding unit used by the decoding unit 1630 for decoding is information on the encoding mode encoded based on whether or not the region includes an out-of-bound region as described above with reference to Figs. 18A to 18G Lt; / RTI &gt;

17 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.

Referring to FIG. 17, in step 1710, the image decoding apparatus 1600 determines whether the first encoding unit to be decoded includes an area outside the boundary of the current picture. It is determined whether the right or left boundary of the first coding unit is out of the right or left boundary of the current picture by referring to the previously decoded coding unit or the upper or lower boundary of the first coding unit is determined as the upper or lower boundary of the current picture Judge whether or not to depart.

In step 1720, the image decoding apparatus 1600 parses the data of the second encoding unit which is not out of the picture boundary among the at least one second encoding unit generated by dividing the first encoding unit based on the determination result of step 1710 . If it is determined in step 1710 that the first coding unit includes an area out of bounds of the current picture, data for the second coding unit that does not deviate from the picture boundary among the second coding units generated by dividing the first coding unit &Lt; / RTI &gt; As described above, the second coding unit may be a coding unit of the depth 'k + 1' which is larger than the depth 'k' of the first coding unit.

In step 1730, the image decoding apparatus 1600 decodes only the data for the second encoding unit which is not out of bounds of the current picture parsed in step 1720. Restores the residual values by entropy decoding, inverse quantization, and inverse frequency transform of the data for the second coding unit which does not deviate from the picture boundary, and adds the predicted values to the predicted values to restore the second coding unit.

The information on the encoding mode of the first encoding unit used by the video decoding apparatus 1600 in decoding may be information encoded based on whether or not the region includes an out-of-bound area as described above with reference to Figs. 18A to 18G .

FIG. 19 is a flowchart illustrating an image encoding method according to another embodiment of the present invention.

Referring to FIG. 19, in operation 1910, the image encoding apparatus 900 determines whether the first encoding unit includes an area outside the boundary of the current picture.

In operation 1920, the image encoding apparatus 900 divides the first encoding unit into at least one second encoding unit based on the determination result in operation 1910. The first encoding unit can be divided into a second encoding unit of depth 'k + 1' that is larger than the depth 'k' of the first encoding unit.

In step 1930, the image encoding apparatus pads the region outside the boundary of the at least one second encoding unit generated as a result of the division in step 1920 with predetermined values. Will be described in detail with reference to FIGS. 20A and 20B.

20A and 20B are views for explaining a method of encoding a picture unit boundary coding unit according to another embodiment of the present invention.

If the determination unit 910 of the image encoding apparatus 900 determines that the first encoding unit 2020 extends over the boundaries of the pictures, the controller 920 converts the first encoding unit 2020 into a smaller size, And divides into second encoding units having a large depth. However, if the second coding unit is the minimum coding unit, the controller 920 can not divide the second coding unit into smaller coding units and can not divide the second coding unit any more. Therefore, It is not distinguished according to the encoding unit.

Therefore, the encoding unit 930 paddes an area of the second encoding units 2024 and 2028 outside the boundary 2010 as shown in FIG. 20B. The pixel values of the region outside the boundary 2010 of the current picture are all set to '0', or the pixel values of the region outside the boundary are set to be the same as the pixel values of the region not outside the adjacent boundary.

Referring again to FIG. 19, in operation 1940, the image encoding apparatus 900 encodes at least one second encoding unit including the padded region in operation 1930.

The encoding unit 930 of the image encoding apparatus 900 generates residual values by predicting the second encoding units 2022 to 2028, and frequency-converts the generated residual values. Quantizes the frequency transform coefficients generated by the frequency transform, and entropy-codes the frequency transform coefficients to encode the second encoding units 2022 to 2028.

In predicting the second encoding units 2024 and 2028 over the boundary 2010, the entire second encoding unit may be predicted, or only the region that is not out of bounds may be predicted. For example, if the second coding unit 2024 over the boundary 2010 is 8x8, the prediction may be performed with an 8x8 size including an out-of-bounds region, or a 4x8 size excluding an out-of-bounds region.

In frequency conversion of the second coding units 2024 and 2028 over the boundary 2010, the entire second coding unit may be frequency-converted, or the frequency may be frequency-converted only in a region not out of bounds.

For example, if the minimum coding unit 2024 across the boundary 2010 is 8x8, frequency conversion may be performed to an 8x8 size including an out-of-bounds region. If a region outside the frequency boundary is also predicted, the region outside the boundary also includes residual values, so that frequency conversion can be performed to the size of the second coding unit. If the region outside the boundary is not predicted and there are no residual values, the region outside the boundary is set to an arbitrary residual value (for example, '0'), and frequency conversion is performed to the size of the second coding unit . Regardless of the prediction, the residual values of the out-of-bounds region are meaningless. Therefore, it is possible to set the residual values of the out-of-bounds region and perform the frequency conversion to an arbitrary value showing the highest efficiency in frequency conversion.

In addition, the encoding unit 930 may perform frequency conversion to a size of 4x8 except for an area outside the boundary. As described above, according to the present invention, since the sizes of the encoding unit, the prediction unit, and the conversion unit can be independently determined, only a region that does not deviate from the boundary can be selectively frequency-converted using a conversion unit smaller than the minimum encoding unit In step 1940, the encoding unit 930, together with the encoding of the second encoding unit, determines whether or not the second encoding unit includes an out-of-bound region as described above with reference to FIGS. 18A and 18G. Information may be encoded.

FIG. 21 is a flowchart illustrating a video decoding method according to another embodiment of the present invention.

Referring to FIG. 21, in step 2110, the determination unit 1610 of the video decoding apparatus 1600 determines whether the first coding unit includes an area outside the boundary of the current picture.

In step 2120, the parsing unit 1620 of the image decoding apparatus 1600 determines whether at least one of the at least one second encoding unit generated by dividing the first encoding unit based on the determination result of step 2110 And parses the data for the second encoding unit. As shown in FIG. 20A, if the second encoding unit is the minimum encoding unit and extends over the boundary, a part of the second encoding unit is an area outside the boundary of the current picture. This area can be padded with a predetermined value as described above with reference to FIG. 19, so that the parsing unit 1620 of the image decoding apparatus decodes the data for at least one second encoding unit including the padded area Parses.

In step 2130, the decoding unit 1630 of the image decoding apparatus 1600 decodes the second encoding unit based on the data for the second encoding unit parsed in step 2120. Restores the residual values by entropy decoding, inverse quantization, and inverse frequency transform of the data for the parsed second encoding unit, and adds the predicted values to the predicted values to restore the second encoding unit. As described above with reference to FIGS. 18A and 18G, information on an encoding mode encoded based on whether or not the second encoding unit includes an out-of-bounds area is decoded, and a second encoding process is performed according to information on the decoded encoding mode The unit can be decoded.

As with the frequency transform described above with reference to FIG. 19, the inverse frequency transform may perform the inverse frequency transform of the entire second encoding unit, or may perform the inverse frequency transform only of the areas not out of bounds. Also, in performing the prediction, the entire second encoding unit may be predicted, or only the region that is not out of bounds may be predicted.

22 is a flowchart illustrating a method of encoding an image according to another embodiment of the present invention.

Referring to FIG. 22, in step 2210, the determination unit 910 of the image encoding apparatus 900 determines whether the first encoding unit includes an area outside the boundary of the current picture.

In step 2220, the image encoding apparatus 900 paddes an area out of the boundary of the first encoding unit to a predetermined value based on the determination result in step 2210. Will be described in detail with reference to FIG. 23A.

FIGS. 23A and 23B are diagrams for explaining a method of coding a picture unit boundary coding unit according to another embodiment of the present invention.

23A, when the determination unit 910 of the image encoding apparatus 900 determines that the first encoding unit 2320 extends over the boundary of a picture, the encoding unit 930 encodes the first encoding unit 2320, The area 2322 outside the middle boundary 2310 is padded as shown in FIG. 23A. The pixel values of the area outside the boundary 2310 of the current picture are all set to '0', or the pixel values of the area outside the boundary are set to be the same as the pixel values of the area not outside the adjacent boundary.

Referring again to FIG. 22, in step 2230, the encoding unit 930 of the image encoding apparatus 900 encodes the first encoding unit 2320 in which the area 2322 outside the boundary 2310 is padded in step 2220, And encoding is performed in an encoding mode using a second encoding unit smaller than the unit 2320. [ If the encoding side and the decoding side share the rules for the padding method, the padded area 2322 on the decoding side can be restored without encoding the padded area 2322 of the first encoding unit 2320 . The encoding unit 930 of the image encoding device 900 uses the second encoding unit smaller than the size of the first encoding unit 2320 for selective encoding of the frame 2324 that does not leave the boundary 2310 And encodes the first encoding unit 2320 in the encoding mode. Will be described in detail with reference to FIG. 23B.

23B, the encoding unit 930 encodes the first encoding unit 2320 in an encoding mode using the second encoding units 2322 to 2328 having a size smaller than the size of the first encoding unit 2320 . Predicts each of the second encoding units according to the encoding mode using the second encoding unit, and frequency-converts the residual values generated as a result of the prediction. The frequency transform coefficients generated as a result of frequency conversion are quantized and entropy-encoded.

The second encoding units 2336 and 2338 of the non-boundary region are encoded in the second encoding units 2336 and 2338, and the second encoding units 2336 and 2338 of the non- 2338 can be encoded. The second encoding units 2332 and 2334 of the boundary region can set a residual value to a predetermined value (e.g., '0') without performing prediction.

Only the information on the motion vectors and pixel values for the second encoding units 2336 and 2338 of the area that does not deviate the boundary 2310 is encoded and the second encoding units 2332 and 2334 ) May not be encoded. The information on the pixel values may be frequency transform coefficients (for example, discrete cosine coefficients) generated by frequency-converting the pixel values included in each of the second encoding units 2332 to 2338.

In addition, in step 2230, the encoding unit 930 may encode information on the encoding mode based on whether or not the second encoding unit includes an out-of-bound area, as described above with reference to Figs. 18A and 18G.

24 is a flowchart illustrating a video decoding method according to another embodiment of the present invention.

Referring to FIG. 24, in step 2410, the determination unit 1610 of the video decoding apparatus 1600 determines whether the first encoding unit includes an area outside the boundary of the current picture.

In step 2420, the parsing unit 1620 of the image decoding apparatus 1600 parses data on the first encoding unit including the padded area based on the determination result in step 2410. [

The data to be parsed may include only information on the second encoding units 2336 and 2338 of the first encoding unit 2320 in the area not outside the boundary 2310 in FIG. 23B. And only information on the motion vectors and pixel values for the second encoding units 2336 and 2338 of the region that does not deviate from the boundary 2310.

In step 2430, the decoding unit 1630 of the image decoding apparatus 1600 decodes the first encoding unit using the parsed data according to the encoding mode using the second encoding unit smaller than the first encoding unit. The second encoding units of the first encoding unit are entropy decoded, inverse quantized, inverse frequency transformed, and predicted and decoded according to the encoding mode using the second encoding unit. As described above with reference to FIGS. 18A and 18G, information on an encoding mode encoded based on whether or not the second encoding unit includes an out-of-bounds area is decoded, and a second encoding process is performed according to information on the decoded encoding mode The unit can be decoded.

Only the second encoding units 2336 and 2338 of the area that does not deviate from the boundary 2310 of the second encoding units 2336 and 2338 in the area that does not deviate the boundary 2310 include only the information of the second encoding units 2336 and 2338 2 encoding unit according to the encoding mode.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible. Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all of the equivalent or equivalent variations will fall within the scope of the present invention. In addition, the system according to the present invention can be embodied as computer-readable codes on a computer-readable recording medium.

For example, an image encoding apparatus and an image decoding apparatus according to an exemplary embodiment of the present invention may include a bus coupled to respective units of the apparatus as shown in FIGS. 1, 2, 4, 5, 9 and 16, And at least one processor coupled to the bus. It may also include a memory coupled to the bus for storing instructions, received messages or generated messages and coupled to the at least one processor for performing the instructions as described above.

In addition, the computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and a carrier wave (for example, transmission via the Internet). The computer-readable recording medium may also be distributed over a networked computer system so that computer readable code can be stored and executed in a distributed manner.

Claims (4)

A video decoding method comprising:
Dividing the first encoding unit into a plurality of second encoding units when the position of the first encoding unit plus the size of the first encoding unit includes a region outside the boundary of the current image, ;
Acquiring division information for the first encoding unit from a bitstream when a position of the first encoding unit plus the size of the first encoding unit does not deviate from a boundary of the current image, Dividing the first encoding unit into a plurality of second encoding units when the division information indicates division of the first encoding unit; And
And decoding the second encoding unit if the second encoding unit is not further divided into smaller encoding units than the second encoding unit,
Wherein the decoding of the second encoding unit comprises:
Wherein the second encoding unit is not further divided into smaller encoding units than the second encoding unit and a position obtained by adding the size of the second encoding unit to the position of the upper left sample of the second encoding unit is Determining one or more prediction units from the second encoding unit and performing prediction using the prediction unit, determining one or more conversion units from the second encoding unit, and using the conversion unit And performing a conversion,
Wherein the current image is divided into a plurality of maximum encoding units,
Wherein the maximum coding unit is hierarchically divided into a coding unit having a depth including at least one of a current depth and a low depth according to the division information. The video decoding method according to claim 1,
And determining whether a right boundary of the first encoding unit is out of a right boundary of the current image. The video decoding method according to claim 1,
Further comprising the step of determining whether a lower boundary of the first encoding unit is out of a lower boundary of the current image. A video decoding apparatus comprising:
Dividing the first encoding unit into a plurality of second encoding units when the position of the first encoding unit plus the size of the first encoding unit includes an area outside the boundary of the current image,
Acquiring division information for the first encoding unit from a bitstream when a position of the first encoding unit plus the size of the first encoding unit does not deviate from a boundary of the current image, An encoding unit determination unit for dividing the first encoding unit into a plurality of second encoding units when the segmentation information indicates division of the first encoding unit; And
And a coding unit decoding unit for decoding the second coding unit when the second coding unit is not further divided into coding units smaller than the second coding unit,
Wherein the decoding unit is configured so that the second encoding unit is not further divided into smaller encoding units than the second encoding unit and a position obtained by adding the size of the second encoding unit from the position of the upper left sample of the second encoding unit is Determining one or more prediction units from the second coding unit when the boundary of the current image is not out of bounds, performing prediction using the prediction unit, determining one or more conversion units from the second coding unit, Conversion is performed using conversion unit,
Wherein the current image is divided into a plurality of maximum encoding units,
Wherein the maximum coding unit is hierarchically divided into a coding unit having a depth including at least one of a current depth and a low depth according to the division information.

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