KR20170043461A - Method and apparatus for adaptive encoding and decoding based on image complexity - Google Patents

Abstract

Disclosed are a method and a device for adaptively encoding and decoding based on image complexity. The encoding device and the decoding device determine the type of a target unit based on the image complexity of the target unit. The encoding device and the decoding device perform inter prediction for the target unit according to the type determined for the target unit. The type of the target unit includes a static unit and a dynamic unit. The maximum depth in division of the target unit and a search range for the target unit are determined depending on the type of the target unit.

Description

Technical Field [0001] The present invention relates to a method and apparatus for adaptive encoding and decoding based on image complexity,

The present invention relates to a decoding method, a decoding apparatus, a coding method, and an encoding apparatus, and more particularly, to a method and apparatus for adaptively performing coding and decoding based on image complexity.

With the continuous development of the information and telecommunication industry, broadcasting service with HD (High Definition) resolution spread worldwide. With this proliferation, many users become accustomed to high resolution and high quality images and / or video.

In order to meet the users' demand for high image quality, many organizations are spurring development on next generation image devices. In addition to High Definition TV (HDTV) and Full HD (FHD) TVs, users' interest in ultra high definition (UHD) TVs with more than four times the resolution of FHD TVs As the interest increases, there is a need for image encoding / decoding techniques for images with higher resolution and image quality.

An apparatus and method for encoding / decoding an image includes an inter prediction technique, an intra prediction technique, and an entropy coding technique to perform encoding / decoding on high resolution and high image quality images Can be used. The inter prediction technique may be a technique of predicting the value of a pixel included in the current picture temporally using a previous picture and / or a temporally subsequent picture. The intra prediction technique may be a technique of predicting the value of a pixel included in the current picture using information of pixels in the current picture. The entropy coding technique may be a technique of allocating a short code to a symbol having a high appearance frequency and allocating a long code to a symbol having a low appearance frequency.

In the encoding and decoding of an image, prediction may mean generating a prediction signal similar to the original signal. The prediction can be broadly classified into a prediction referring to a spatial reconstructed image, a prediction referring to a temporal restored image, and a prediction on other symbols. That is to say, a temporal reference may refer to a temporal reconstruction image, and a spatial reference may refer to a spatial reconstruction image.

The current block may be the current block to be encoded or decoded. The current block may be named a target block or target unit. In coding, the current block can be named as the current block or the current unit to be coded. In decoding, the current block can be named a block to be decoded or a unit to be decoded.

Inter prediction may be a technique of predicting a current block using temporal references and spatial references. Intra prediction may be a technique of predicting a current block using only spatial reference.

In general, for inter prediction of blocks of multiple images, the same inter prediction is used. For example, the same inter prediction can be applied without considering the image characteristics of the image including the current block. If the same inter prediction is always used, the complexity of the encoding apparatus can be increased and the efficiency of encoding can be lowered. Particularly, in the prediction of a coding unit including a static area, when inter-predictions are performed on more sub-divided blocks than necessary, the amount of motion information to be transmitted from the encoding apparatus to the decoding apparatus may increase , The encoding efficiency may be lowered due to an increase in the amount of motion information.

One embodiment of the present invention can provide a method and apparatus for improving coding efficiency through a technique for performing adaptive coding and decoding based on characteristics of an image.

One embodiment of the present invention can provide a method and apparatus for reducing the complexity of an encoding apparatus through a technique for performing adaptive encoding and decoding based on characteristics of an image.

One embodiment may provide a method and apparatus for constraining the number of times that a coding unit classified into a static region is divided into subunits based on a quadtree.

One embodiment may provide a method and apparatus for encoding a coding unit as a unit of a larger size by restricting the number of times that a coding unit classified as a static region is divided into lower units.

One embodiment can provide a method and apparatus for reducing the complexity of an encoding apparatus by encoding a coding unit classified as a static region as a unit of a larger size.

One embodiment can provide a method and apparatus for reducing the amount of motion information transmitted from an encoding apparatus to a decoding apparatus by encoding a coding unit classified as a static region as a unit of a larger size.

One embodiment may provide a method and apparatus for reducing the bit precision and search range of a motion vector under the assumption that the correlation between the static unit and adjacent neighboring blocks is high.

One embodiment of the present invention can provide a method and apparatus for improving coding efficiency and decreasing the complexity of a coding apparatus by reducing the bit precision and search area of a motion vector.

Determining, on a side, the type of the target unit based on the image complexity of the target unit; And performing inter-prediction on the target unit in accordance with the determined type.

 A method and apparatus for improving coding efficiency through a technique for performing adaptive coding and decoding based on image characteristics are provided.

There is provided a method and apparatus for reducing the complexity of an encoding apparatus through a technique for performing adaptive encoding and decoding based on characteristics of an image.

There is provided a method and apparatus for constraining the number of times that a coding unit classified into a static region is divided into subunits based on a quadtree.

There is provided a method and apparatus for encoding a coding unit as a unit of a larger size by restricting the number of times that a coding unit classified as a static area is divided into lower units.

There is provided a method and apparatus for reducing the complexity of an encoding apparatus by encoding a coding unit classified as a static region as a unit of a larger size.

There is provided a method and apparatus for reducing the amount of motion information transmitted from an encoding device to a decoding device by encoding a coding unit classified as a static area as a unit of a larger size.

There is provided a method and apparatus for reducing the bit precision and search range of a motion vector under the assumption that the correlation between the static unit and adjacent neighboring blocks is high.

There is provided a method and an apparatus for improving the coding efficiency and reducing the complexity of the encoding apparatus by reducing the bit precision and the search area of the motion vector.

1 is a block diagram illustrating a configuration of an encoding apparatus to which the present invention is applied.
2 is a block diagram illustrating a configuration of a decoding apparatus to which the present invention is applied.
3 is a diagram schematically showing a division structure of an image when coding and decoding an image.
Figs. 4A to 7H are diagrams showing the form of a prediction unit (PU) that a coding unit (CU) can include.
5 is a diagram showing a form of a conversion unit (TU) which can be included in a coding unit (CU).
6 is a diagram for explaining an embodiment of an intra prediction process.
7 is a diagram for explaining an embodiment of the inter prediction process.
8 is a flowchart of an inter prediction method according to an embodiment.
FIG. 9 shows a difference image between a current picture and a reference picture according to an example.
10 shows type flags of a target unit and restored neighboring units according to an example.
11 is a structural diagram of an electronic apparatus for implementing an encoding apparatus and / or a decoding apparatus according to an embodiment.

The following detailed description of exemplary embodiments refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments. It should be understood that the various embodiments are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the location or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the embodiments. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the exemplary embodiments is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained.

In the drawings, like reference numerals refer to the same or similar functions throughout the several views. The shape and size of the elements in the figures may be exaggerated for clarity.

When it is mentioned that a component is "connected" or "connected" to another component, the two components may be directly connected or connected to each other, It is to be understood that other components may be present in the middle of the components. Also, in the exemplary embodiments, the description of "comprising" a specific configuration does not exclude a configuration other than the specific configuration, and the additional configuration is not limited to the implementation of the exemplary embodiments or the technical idea of the exemplary embodiments. Range. ≪ / RTI >

The terms first and second, etc. may be used to describe various components, but the components should not be limited by the terms above. The above terms are used to distinguish one component from another. For example, without departing from the scope of the right, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

In addition, the components shown in the embodiments are shown independently to represent different characteristic functions, which does not mean that each component is composed of separate hardware or one software constituent unit. That is, each component is listed as each component for convenience of explanation. For example, at least two of the components may be combined into a single component. Also, one component can be divided into a plurality of components. The integrated embodiments and the separate embodiments of each of these components are also included in the scope of the right without departing from the essence.

Also, some components are not essential components to perform essential functions, but may be optional components only to improve performance. Embodiments may be implemented only with components that are essential to implementing the essentials of the embodiments, and structures within which the optional components are excluded, such as, for example, components used only for performance enhancement, are also included in the scope of the right.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate embodiments of the present invention by those skilled in the art. In the following description of the embodiments, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

Hereinafter, an image may refer to one picture constituting a video, and may also represent the video itself. For example, "encoding and / or decoding of an image" may mean "encoding and / or decoding of video ", which means" encoding and / or decoding of one of the images constituting a video " It is possible.

First, terms used in the embodiments will be described.

Unit: A "unit" can represent a unit of encoding and decoding of an image. The meanings of units and blocks may be the same. In addition, the terms "unit" and "block"

 The unit (or block) may be an MxN array of samples. M and N may be positive integers, respectively. A unit can often be an array of two-dimensional samples. The sample may be a pixel or a pixel value.

 In coding and decoding of an image, a unit may be an area generated by division of one image. One image may be divided into a plurality of units. In the coding and decoding of the image, predetermined processing on the unit may be performed depending on the type of the unit. Depending on the function, the type of the unit can be classified into a macro unit, a coding unit (CU), a prediction unit (PU), and a transform unit (TU). One unit may be further subdivided into smaller units having a smaller size than the unit.

 The block partitioning information may include information on the depth of the unit. The depth information may indicate the number and / or the number of times the unit is divided.

 One unit can be divided hierarchically into a plurality of subunits having depth information based on a tree structure. That is to say, the unit and the lower unit generated by the division of the unit can correspond to the node and the child node of the node, respectively. Each divided subunit may have depth information. Since the depth information of the unit indicates the number and / or degree of division of the unit, the division information of the lower unit may include information on the size of the lower unit.

 In the tree structure, the top node can correspond to the first unit that has not been partitioned. The superordinate node may be referred to as a root node. Also, the uppermost node may have a minimum depth value. At this time, the uppermost node can have a level 0 depth.

 A node with a depth of level 1 can represent a unit created as the first unit is once partitioned. A node with a depth of level 2 may represent a unit created as the first unit is divided twice.

 A node with a depth of level n may represent a unit created as the first unit is divided n times.

 The leaf node may be the lowest node, and may be a node that can not be further divided. The depth of the leaf node may be the maximum level. For example, the default value of the maximum level may be three.

Transform Unit: A transform unit may be a base unit in residual signal coding and / or residual signal decoding such as transform, inverse transform, quantization, inverse quantization, transform coefficient coding, and transform coefficient decoding . One conversion unit can be divided into a plurality of conversion units having a smaller size.

Prediction Unit: A prediction unit may be a basic unit in performing prediction or compensation. The prediction unit may be partitioned into a plurality of partitions. Multiple partitions may also be a base unit in performing prediction or compensation. The partition generated by the division of the prediction unit may also be a prediction unit.

Reconstructed Neighbor Unit: The reconstructed neighboring unit may be a unit that has already been encoded or decoded around the encoding target unit or the target unit to be decoded. The restored neighboring unit may be a spatial adjacent unit or a temporally adjacent unit for the target unit.

Predictive unit partition: The predictive unit partition may mean a type in which the predictive unit is divided.

Parameter Set: A parameter set may correspond to header information among structures in a bitstream. For example, the parameter set may include a sequence parameter set, a picture parameter set, and an adaptation parameter set.

Ratedistortion optimization: The encoding apparatus uses rate distortion optimization to provide a high coding efficiency using a combination of the size of the coding unit, the prediction mode, the size of the prediction unit, the motion information, and the size of the conversion unit .

 The rate distortion optimization scheme may calculate the ratedistortion cost of each combination to select the optimal combination from among the combinations above. The rate distortion cost can be calculated using Equation (1) below. In general, the combination in which the rate distortion cost is minimized can be selected as the optimal combination in the rate distortion optimization method.

D can represent distortion. D may be the mean square error of the original transform coefficients within the transform block and the difference values between the restored transform coefficients.

R can represent the rate. R can represent the bit rate using related context information.

lambda can represent a Lagrangian multiplier. R may include not only encoding parameter information such as a prediction mode, motion information, and coded block flag, but also bits generated by encoding the transform coefficients.

The encoding apparatus performs inter prediction and / or intra prediction, conversion, quantization, entropy encoding, inverse quantization, and inverse transformation to calculate the correct D and R, and this process can greatly increase the complexity in the encoding apparatus have.

Reference picture: The reference picture may be an image used for inter prediction or motion compensation. The reference picture may be a picture including a reference unit referred to by the target unit for inter prediction or motion compensation. The meanings of pictures and images may be the same. In addition, the terms "picture" and "image" may be used interchangeably.

Reference picture list: The reference picture list may be a list including reference pictures used for inter prediction or motion compensation. The type of the reference picture list may be a list combination (LC), a list 0 (L0), and a list 1 (L1).

Motion Vector (MV): A motion vector may be a two-dimensional vector used in inter prediction. For example, MV can be expressed in the form (mv _x , mv _y ). mv _x may represent a horizontal component, and mv _y may represent a vertical component.

 The MV may indicate an offset between the target picture and the reference picture.

Search range: The search area may be a two-dimensional area where an MV search is performed during inter prediction. For example, the size of the search area may be MxN. M and N may be positive integers, respectively.

1 is a block diagram illustrating a configuration of an encoding apparatus to which the present invention is applied.

The encoding apparatus 100 may be a video encoding apparatus or an image encoding apparatus. The video may include one or more images. The encoding device 110 may sequentially encode one or more images of the video according to time.

1, an encoding apparatus 100 includes an inter prediction unit 110, an intra prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, a quantization unit 140, An inverse quantization unit 160, an inverse transform unit 170, an adder 175, a filter unit 180, and a reference picture buffer 190. [

The encoding apparatus 100 may perform encoding in an intra mode and / or an inter mode on an input image. The input image can be referred to as the current image which is the object of the current encoding.

Also, the encoding apparatus 100 can generate a bitstream including encoding information through encoding of the input image, and output the generated bitstream.

When the intra mode is used, the switch 115 can be switched to intra. When the inter mode is used, the switch 115 can be switched to the inter.

The encoding apparatus 100 may generate a prediction block for an input block of an input image. Also, after the prediction block is generated, the encoding device 100 may code the residual of the input block and the prediction block. The input block may be referred to as the current block which is the current encoding target.

When the prediction mode is the intra mode, the intraprediction unit 120 can use the pixel value of the already coded block around the current block as a reference pixel. The intra predictor 120 can perform spatial prediction of a current block using a reference pixel and generate prediction samples of a current block through spatial prediction.

The inter prediction unit 110 may include a motion prediction unit and a motion compensation unit.

When the prediction mode is the inter mode, the motion prediction unit can search the reference image for the best match with the current block in the motion estimation process, and derive the motion vector for the current block and the searched area. The reference picture may be stored in the reference picture buffer 190 and may be stored in the reference picture buffer 190 when the coding and / or decoding of the reference picture is processed.

The motion compensation unit may generate a prediction block by performing motion compensation using a motion vector. Here, the motion vector may be a two-dimensional vector used for inter prediction. The motion vector may also indicate an offset between the current image and the reference image.

The subtractor 125 may generate a residual block that is a difference between the input block and the prediction block. The residual block may be referred to as a residual signal.

The transforming unit 130 may perform a transform on the residual block to generate a transform coefficient, and output the generated transform coefficient. Here, the transform coefficient may be a coefficient value generated by performing a transform on the residual block. When the transform skip mode is applied, the transforming unit 130 may omit the transform for the residual block.

A quantized transform coefficient level can be generated by applying quantization to the transform coefficients. Hereinafter, in the embodiments, the quantized transform coefficient level may also be referred to as a transform coefficient.

The quantization unit 140 may generate a quantized transform coefficient level by quantizing the transform coefficient according to the quantization parameter. The quantization unit 140 may output the generated quantized transform coefficient levels. At this time, the quantization unit 140 can quantize the transform coefficient using the quantization matrix.

The entropy encoding unit 150 can generate a bitstream by performing entropy encoding according to the probability distribution based on the values calculated by the quantization unit 140 and / or the encoding parameter values calculated in the encoding process . The entropy encoding unit 150 may output the generated bitstream.

The entropy encoding unit 150 may perform entropy encoding on information for decoding an image in addition to information on pixels of the image. For example, the information for decoding the image may include a syntax element or the like.

The encoding parameters may be information required for encoding and / or decoding. The encoding parameter may include information that is encoded in the encoding apparatus and transferred to the decoding apparatus, and may include information that can be inferred in the encoding or decoding process. For example, as information transmitted to the decoding apparatus, there is a syntax element.

For example, the coding parameters include a prediction mode, a motion vector, a reference picture index, a coding block pattern, a residual signal presence, a transformation coefficient, a quantized transform coefficient, a quantization parameter, a block size, Information, or the like. The prediction mode may indicate an intra prediction mode or an inter prediction mode.

The residual signal may mean a difference between the original signal and the prediction signal. Alternatively, the residual signal may be a signal generated by transforming the difference between the original signal and the prediction signal. Alternatively, the residual signal may be a signal generated by transforming and quantizing the difference between the original signal and the prediction signal. The residual block may be a residual signal on a block basis.

When entropy coding is applied, a small number of bits can be assigned to a symbol having a high probability of occurrence, and a large number of bits can be assigned to a symbol having a low probability of occurrence. As the symbol is represented through this allocation, the size of the bit string for the symbols to be encoded can be reduced. Therefore, the compression performance of the image encoding can be improved through the entropy encoding.

In addition, for entropy encoding, encoding methods such as exponential golomb, context adaptive variable length coding (CAVLC), and context adaptive binary arithmetic coding (CABAC) may be used . For example, the entropy encoding unit 150 may perform entropy encoding using a Variable Length Coding / Code (VLC) table. For example, the entropy encoding unit 150 may derive a binarization method for a target symbol. In addition, the entropy encoding unit 150 may derive a probability model of a target symbol / bin. The entropy encoding unit 150 may perform entropy encoding using the derived binarization method or probability model.

Since encoding is performed through inter prediction by the encoding apparatus 100, the encoded current image can be used as a reference image for another image (s) to be processed later. Accordingly, the encoding apparatus 100 can decode the encoded current image again, and store the decoded image as a reference image. The inverse quantization and inverse transform of the current encoded image for decoding can be processed.

The quantized coefficients may be inversely quantized in the inverse quantization unit 160. And may be inversely transformed in the inverse transform unit 170. [ The dequantized and inverse transformed coefficients may be combined with a prediction block via an adder 175. A reconstructed block may be generated by summing the dequantized and inverse transformed coefficients and the prediction block.

The restoration block may pass through the filter unit 180. The filter unit 180 may apply at least one of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to a reconstructed block or a reconstructed picture. The filter unit 180 may be referred to as an adaptive inloop filter.

The deblocking filter can remove block distortion occurring at the boundary between the blocks. SAO may add a proper offset value to the pixel value to compensate for coding errors. The ALF can perform filtering based on the comparison between the restored image and the original image. The reconstructed block having passed through the filter unit 180 may be stored in the reference picture buffer 190.

2 is a block diagram illustrating a configuration of a decoding apparatus to which the present invention is applied.

The decoding apparatus 200 may be a video decoding apparatus or an image decoding apparatus.

2, the decoding apparatus 200 includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an intra prediction unit 240, an inter prediction unit 250, an adder 255, A filter unit 260, and a reference picture buffer 270.

The decoding apparatus 200 can receive the bit stream output from the encoding apparatus 100. [ The decoding apparatus 200 may perform decoding of an intra mode and / or an inter mode with respect to a bit stream. Also, the decoding apparatus 200 can generate a reconstructed image through decoding and output the generated reconstructed image.

For example, switching to an intra mode or an inter mode according to a prediction mode used for decoding may be performed by a switch. When the prediction mode used for decoding is the intra mode, the switch can be switched to intra. When the prediction mode used for decoding is the inter mode, the switch can be switched to the inter.

The decoding apparatus 200 can obtain a reconstructed residual block from the input bitstream and generate a prediction block. Once the reconstructed residual block and prediction block are obtained, the decoding apparatus 200 can generate a reconstruction block by adding the reconstructed residual block and the prediction block.

The entropy decoding unit 210 may generate the symbols by performing entropy decoding on the bitstream based on the probability distribution. The generated symbols may include symbols in the form of quantized coefficients. Here, the entropy decoding method may be similar to the above-described entropy encoding method. For example, the entropy decoding method may be the inverse of the above-described entropy encoding method.

The quantized coefficients may be inversely quantized in the inverse quantization unit 220. Also, the inverse quantized coefficient may be inversely transformed by the inverse transform unit 230. As a result that the quantized coefficients are inversely quantized and inversely transformed, reconstructed residual blocks can be generated. At this time, the inverse quantization unit 220 may apply the quantization matrix to the quantized coefficients.

When the intra mode is used, the intra prediction unit 240 can generate a prediction block by performing spatial prediction using the pixel value of the already coded block around the current block.

The inter prediction unit 250 may include a motion compensation unit. When the inter mode is used, the motion compensation unit can generate a prediction block by performing motion compensation using a motion vector and a reference image. The reference picture may be stored in the reference picture buffer 270.

The reconstructed residual block and the prediction block may be added through an adder 255. The adder 255 may generate the restored block by adding the restored residual block and the predicted block.

The restoration block may pass through the filter unit 260. The filter unit 260 may apply at least one of a deblocking filter, SAO, and ALF to a restoration block or a restoration picture. The filter unit 260 may output a restored image. The restored image is stored in the reference picture buffer 270 and can be used for inter prediction.

3 is a diagram schematically showing a division structure of an image when coding and decoding an image.

To efficiently divide an image, a coding unit (CU) can be used in coding and decoding. A unit may be a term collectively referred to as 1) a block containing image samples and 2) a syntax element. For example, "division of a unit" may mean "division of a block corresponding to a unit ".

Referring to FIG. 3, the image 300 can be sequentially divided into units of a Largest Coding Unit (LCU), and the divided structure of the image 300 can be determined according to the LCU. Here, the LCU can be used in the same sense as a coding tree unit (CTU).

The divided structure may mean a distribution of a coding unit (CU) for efficiently encoding an image in the LCU 310. [ This distribution can be determined depending on whether one CU is divided into four CUs. The horizontal size and the vertical size of the CU generated by the division may be half of the horizontal size and half the vertical size of the CU before division, respectively. The partitioned CUs can be recursively partitioned into four CUs that have been reduced in half in the horizontal and vertical sizes in the same manner.

At this time, the division of the CU can be made recursively up to a predetermined depth. The depth information may be information indicating the size of the CU. Depth information can be stored for each CU. For example, the depth of the LCU may be zero, and the depth of the Smallest Coding Unit (SCU) may be a predetermined maximum depth. Here, the LCU may be a CU having a maximum coding unit size as described above, and the SCU may be a CU having a minimum coding unit size.

The LCU 310 may begin to divide and the depth of the CU may increase by one each time the horizontal and vertical sizes of the CU are reduced by half. For each depth, the unpartitioned CU may have a size of 2Nx2N. Also, in the case of a CU to be divided, a CU having a size of 2Nx2N can be divided into four CUs having an NxN size. The size of N can be reduced by half each time the depth is increased by one.

Referring to FIG. 3, a LCU with a depth of 0 may be 64x64 pixels. 0 may be the minimum depth. An SCU with a depth of 3 may be 8x8 pixels. 3 may be the maximum depth. At this time, the CU of 64x64 pixels, which is an LCU, can be represented by a depth 0. The CU of 32x32 pixels can be represented by a depth of one. The CU of 16x16 pixels can be represented by a depth of two. The CU of 8x8 pixels that are SCUs can be represented by depth 3.

In addition, information on whether or not the CU is divided can be expressed through division information of the CU. The division information may be 1-bit information. All CUs except SCU can contain partition information. For example, if the CU is not divided, the value of the partition information of the CU may be 0, and if the CU is partitioned, the partition information of the CU may be 1.

4A to 4H are diagrams showing the form of a prediction unit (PU) which the coding unit (CU) can include.

A CU that is not further divided among the CUs divided from the LCU may be divided into one or more Prediction Units (PUs). Such a partition may also be referred to as a partition.

The PU can be a base unit for prediction. The PU may be coded and decoded in either a skip mode, an inter mode, or an intra mode. The PU can be divided into various forms according to each mode.

As shown in FIG. 4A, in the skip mode, there may not be a partition in the CU. In the skip mode, the 2Nx2N mode 410 having the same sizes of PU and CU without division can be supported.

In inter mode, eight subdivided forms within the CU can be supported. For example, in the inter mode, 2Nx2N mode 410, 2NxN mode 415, Nx2N mode 420, NxN mode 425, 2NxnU mode 430, 2NxnD mode 435, nLx2N mode 440, Mode 445 may be supported.

In the intra mode, 2Nx2N mode 410 and NxN mode 425 may be supported.

5 is a diagram showing a form of a conversion unit (TU) which can be included in a coding unit (CU).

A Transform Unit (TU) may be the basic unit used for transform, quantization, inverse transform, and dequantization processes within a CU. The TU may have a square shape or a rectangular shape.

Of the CUs segmented from the LCU, the CUs that are no longer divided into CUs may be divided into one or more TUs. At this time, the partition structure of the TU may be a quadtree structure. For example, as shown in FIG. 5, one CU 510 may be divided once or more according to the quad tree structure. Through partitioning, one CU 510 can be composed of TUs of various sizes.

6 is a diagram for explaining an embodiment of an intra prediction process.

The number of intra prediction modes can be fixed to 35 irrespective of the size of the prediction unit.

The prediction mode may include two non-directional modes and 33 directional modes as shown in Fig. The two non-directional modes may include a DC mode and a Planar mode.

The number of prediction modes may differ depending on the type of color component. For example, the number of prediction modes may be different depending on whether the color component is a luma signal or a chroma signal.

The PU may have a square shape with a size of NxN or a size of 2Nx2N. The size of NxN may include 4x4, 8x8, 16x16, 32x32 and 64x64. The unit of the PU may be the size of at least one of CU, PU, and TU.

The intra-encoding and / or decoding may be performed using a sample value or an encoding parameter included in the restored unit in the vicinity.

7 is a diagram for explaining an embodiment of the inter prediction process.

The rectangle shown in Fig. 7 may represent an image (or a picture). In Fig. 7, arrows can indicate the prediction direction. That is, the image can be encoded and / or decoded according to the prediction direction.

Each picture (or picture) can be classified into an I picture (Intra Picture), a P picture (Uniprediction Picture), and a B picture (Biprediction Picture) according to the coding type. Each picture can be encoded according to the encoding type of each picture.

If the image to be encoded is an I picture, the image can be encoded for the image itself without inter prediction. If the picture to be coded is a P picture, the picture can be encoded through inter prediction which uses the reference picture only in the forward direction. When the image to be coded is a B picture, it can be coded by inter-prediction using reference pictures on both sides of the forward and backward directions, and can be coded by inter prediction using reference pictures in one direction of forward and backward directions.

The P picture and the B picture to be encoded and / or decoded using the reference picture can be regarded as an image in which inter prediction is used.

In the following, inter prediction in the inter mode according to the embodiment will be described in detail.

In the inter mode, the encoding apparatus 100 and the decoding apparatus 200 can perform prediction and / or motion compensation on the encoding target unit and the decoding target unit. For example, the encoding apparatus 100 or the decoding apparatus 200 can perform prediction and / or motion compensation by using motion information of a reconstructed neighboring unit as motion information of a current frame to be encoded or a current frame to be decoded. Here, the to-be-encoded unit or the to-be-decoded unit may mean a prediction unit and / or a prediction unit partition.

Inter prediction can be performed using reference pictures and motion information. Further, the inter prediction may use the skip mode described above.

The reference picture may be at least one of a previous picture of the current picture or a subsequent picture of the current picture. At this time, the inter prediction can predict the block of the current picture based on the reference picture. Here, the reference picture may refer to an image used for prediction of a block.

At this time, an area in the reference picture can be specified by using a reference picture index refIdx indicating a reference picture, a motion vector to be described later, or the like.

The inter prediction can select a reference block corresponding to the current block in the reference picture and the reference picture, and can generate a prediction block for the current block using the selected reference block. The current block may be a current block of the current picture to be coded or decoded.

The motion information may be derived during inter-prediction by the encoding apparatus 100 and the decoding apparatus 200, respectively. Further, the derived motion information can be used to perform inter prediction.

At this time, the encoding apparatus 100 and the decoding apparatus 200 use the motion information of the restored neighboring block and / or the motion information of the collocated block (col block) Can be improved. The call block may be a block corresponding to a current block in a collocated picture (col picture).

The reconstructed neighboring block may be a block in the current picture, and may be a block reconstructed through encoding and / or decoding. The restoration block may be a neighboring block adjacent to the current block and / or a block located at the outer corner of the current block. Here, a block located at the outer corner of the current block may be a block vertically adjacent to a neighboring block that is laterally adjacent to the current block, or a block that is laterally adjacent to a neighboring block vertically adjacent to the current block.

For example, the restored peripheral unit may be a unit located on the left side of the target unit, a unit located on the upper end of the target unit, a unit located on the lower left corner of the target unit, a unit located on the upper right corner of the target unit, It may be a unit located in a corner.

Each of the encoding apparatus 100 and the decoding apparatus 200 can determine a block present in a position corresponding to a current block spatially in a call picture and determine a predetermined relative position based on the determined block. The predetermined relative position may be an inner and / or outer position of the block spatially present at a position corresponding to the current block. In addition, each of the encoding apparatus 100 and the decoding apparatus 200 can derive a call block based on the determined predetermined relative positions. Here, the call picture may be one picture among at least one reference picture included in the reference picture list.

The block in the reference picture may exist at a position spatially corresponding to the position of the current block in the reconstructed reference picture. That is to say, the position of the current block in the current picture and the position of the block in the reference picture can correspond to each other. Hereinafter, the motion information of the block included in the reference picture may be referred to as temporal motion information.

The derivation method of the motion information can be changed according to the prediction mode of the current block. For example, there may be an Advanced Motion Vector Predictor (AMVP) and a merge as prediction modes applied for inter prediction.

For example, when AMVP is applied as a prediction mode, each of the encoding apparatus 100 and the decoding apparatus 200 uses a restored motion vector of a neighboring block and / or a motion vector of a call block to generate a predicted motion vector candidate You can create a list. The motion vector of the restored neighboring block and / or the motion vector of the call block may be used as the predicted motion vector candidate.

The bit stream generated by the encoding apparatus 100 may include a predicted motion vector index. The predicted motion vector index may indicate an optimal predicted motion vector selected from the predicted motion vector candidates included in the predicted motion vector candidate list. The predicted motion vector index may be transmitted from the encoding apparatus 100 to the decoding apparatus 200 through the bitstream.

The decoding apparatus 200 can use the predicted motion vector index to select a predicted motion vector of the current block from the predicted motion vector candidates included in the predicted motion vector candidate list.

The encoding apparatus 100 can calculate a motion vector difference (MVD) between a motion vector of a current block and a predictive motion vector, and encode the MVD. The bitstream may include an encoded MVD. The MVD may be transmitted from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. At this time, the decoding apparatus 200 can decode the received MVD. The decoding apparatus 200 can derive the motion vector of the current block through the sum of the decoded MVD and the predicted motion vector.

The bitstream may include a reference picture index indicating a reference picture. The reference picture index may be transmitted from the encoding apparatus 100 to the decoding apparatus 200 through a bit stream. The decoding apparatus 200 can predict the motion vector of the current block using the motion information of the neighboring block and derive the motion vector of the current block using the predicted motion vector and the motion vector difference. The decoding apparatus 200 can generate a prediction block for the current block based on the derived motion vector and the reference picture index information.

The motion information of the reconstructed peripheral unit can be used for the current frame to be coded and the current frame to be decoded. Therefore, in the specific inter prediction mode, the coding apparatus 100 may not separately encode the motion information for the target unit. If the motion information of the target unit is not coded, the amount of bits to be transmitted to the decoding apparatus 200 can be reduced, and the coding efficiency can be improved. For example, there may be a skip mode and / or a merge mode as inter prediction modes in which motion information of the target unit is not encoded. At this time, the encoding apparatus 100 and the decoding apparatus 200 may use an identifier and / or index indicating which one of the reconstructed neighboring units is used as motion information of the target unit.

Another example of a method of deriving motion information is a merge. A merge may mean a merging of movements for a plurality of blocks. Merging may mean applying motion information of one block to another block as well. When the merge is applied, each of the encoding apparatus 100 and the decoding apparatus 200 can generate a merge candidate list using the motion information of the restored neighboring block and / or the motion information of the call block have. The motion information may include at least one of 1) a motion vector, 2) an index for a reference image, and 3) a prediction direction. The prediction direction may be unidirectional or bidirectional.

At this time, the merge can be applied in units of CU or PU. When the merge is performed in units of CU or PU, the encoding apparatus 100 may transmit the predefined information to the decrypting apparatus 200 through the bit stream. The bitstream may contain predefined information. The predefined information may include: 1) information indicating whether to perform a merge by block partitions, and 2) information on which of neighboring blocks adjacent to the current block to merge with. For example, neighboring blocks of the current block may include a left adjacent block of the current block, an upper adjacent block of the current block, and a temporal adjacent block of the current block.

The merge candidate list may represent a list of stored motion information. Also, the merge candidate list can be created before the merge is performed. The motion information stored in the merge candidate list may be 1) motion information of a neighboring block adjacent to the current block, or 2) collocated block motion information corresponding to a current block in the reference image. Also, the motion information stored in the merge candidate list may be new motion information generated by a combination of motion information already present in the merge candidate list.

The skip mode may be a mode in which the information of the neighboring blocks is directly applied to the current block. The skip mode may be one of modes used for inter prediction. When the skip mode is used, the encoding apparatus 100 can transmit only information on which block's motion information is to be used as motion information of the current block to the decoding apparatus 200 through a bitstream. The encoding apparatus 100 may not transmit the other information to the decryption apparatus 200. [ For example, the other information may be syntax information. The syntax information may include motion vector difference information.

8 is a flowchart of an inter prediction method according to an embodiment.

Hereinafter, a method of performing inter-prediction with respect to a target unit in an image encoding process will be described. For example, the target unit may be a CU.

In step 810, the inter-prediction unit 110 may determine the type of the target unit based on the image complexity of the target unit.

Here, the type of the target unit may include a static area and a dynamic area, and the target unit may be classified into one of a static area and a dynamic area.

The image complexity may be determined based on a comparison between the target unit and the corresponding unit. That is to say, the result of the predefined operation on the value representing the target unit and the value representing the corresponding unit may be used as the image complexity. Here, the value representing the target unit may be the LCU of the target unit, and the value representing the corresponding unit may be the LCU of the corresponding unit.

The image complexity can be determined based on the Sum of Absolute Difference (SAD) of the LCU of the target unit and the LCU of the corresponding unit. For example, the image complexity may be the SAD of the LCU of the target unit and the corresponding unit LCU, and may be a value generated based on the SAD of the LCU of the target unit and the corresponding unit LCU.

Alternatively, the image complexity may be determined based on the Sum of Squared Error (SSE) of the LCU of the target unit and the LCU of the corresponding unit. For example, the image complexity may be the SSE of the LCU of the target unit and the corresponding unit LCU, and may be a value generated based on the SSE of the LCU of the target unit and the corresponding unit LCU.

The corresponding unit may be a unit corresponding to the target unit. For example, the corresponding unit may be a call unit corresponding to the target unit in the reference picture. The position of the target unit in the current picture and the position of the corresponding unit in the reference picture can correspond to each other.

The inter-prediction unit 110 can determine the type of the target unit based on the comparison between the image complexity of the target unit and the predetermined threshold value Th. The predetermined threshold value Th may be a value that is optimally determined for determining the type of the target unit. For example, when the image complexity or the SAD of the target unit is equal to or larger than the predetermined threshold value Th, the inter-prediction unit 110 can determine the type of the target unit as a dynamic unit. The inter-prediction unit 110 can determine the type of the target unit as a static unit when the image complexity or the SAD of the target unit is smaller than the predetermined threshold value Th.

The inter-prediction unit 110 can set the value of the flag "type flag" according to the result of comparison between the image complexity of the target unit and the predetermined threshold value Th.

If the image complexity or SAD of the target unit is equal to or greater than the predetermined threshold value Th, the inter-prediction unit 110 sets the type flag to "true "," logical 1 " Can be set. The inter-prediction unit 110 may set the "type flag" to " false ", "logic 0" or " false " if the image complexity or SAD of the target unit is smaller than the predetermined threshold value Th And can be set to a predetermined second value. For example, the flag "type flag" may indicate the type of the target unit. If the value of the "type flag" is a predefined first value, the target unit may be a dynamic unit. If the value of the "type flag" is a predetermined second value, the target unit may be a static unit.

When the slice type of the slice of the target unit is a non-slice (Bslice), the inter-prediction unit 110 can use two reference pictures in determining the type of the target unit. When the slice type of the slice of the target unit is non-slice, the inter-prediction unit 110 can calculate the first SAD of the LCU of the target unit and the first corresponding unit of the reference picture 0, The second SAD of the LCU of the second corresponding unit of the picture 1 can be calculated. The inter prediction unit 110 may use the average of the first SAD and the second SAD as the SAD for the target unit.

The type of the target unit can be classified into an initial type and a final type. The initial type may be the type of the target unit indicated by the "type flag". The final type may be of a type determined based on the weighted sum of the "type flag" of the target unit and the "type flag" of the adjacent unit. The adjacent unit may be a unit adjacent to the target unit that has already been encoded or decoded before processing for the target unit. The adjacent units may be plural. For example, a plurality of adjacent units may include at least one of a unit adjacent to the target unit at the upper left, a unit adjacent to the upper end of the target unit, a unit at the upper right of the target unit, and a unit adjacent to the target unit at the left side .

The inter prediction unit 110 can determine the final type of the target unit based on the image complexities of the target unit and the neighboring units. For example, when the sum of the weighted values of the "type flag" of the target unit and the "type flag" of the target unit is greater than or equal to the predetermined third value, the inter- Can be decided as a unit. For example, when the sum of the weighted values of the "type flag" of the target unit and the "type flag" of the target unit is smaller than the predetermined fourth value, the inter-prediction unit 110 sets the final type of the target unit as static Can be decided as a unit.

In step 820, the inter-prediction unit 110 may perform inter-prediction on the target unit according to the determined type.

The inter-prediction unit 110 can perform prediction on a target unit using conventional inter prediction if the type of the target unit is a dynamic unit. Here, the conventional inter prediction may be the inter prediction described above with reference to Figs.

The inter-prediction unit 110 can perform prediction on the target unit using the simplified inter prediction if the type of the target unit is a static unit.

The inter-prediction unit 110 may perform prediction for a target unit using different inter-predictions for a plurality of types.

Different inter prediction may be different from each other in, for example, 1) the number of quadtree division for the target unit, 2) the number of reference pictures, or 3) can do.

For example, the simplified inter prediction may be an inter prediction that limits the number of quadtree division times for the target unit. The simplified inter prediction may be a prediction that performs encoding and / or decoding with a prediction unit of a larger size by limiting the number of quadtree division times for the target unit. The inter prediction unit 110 can perform the division on the target unit by applying a smaller maximum depth to the dynamic unit for the static unit.

Alternatively, the simplified inter prediction may be a prediction in which the number of reference pictures of the inter prediction is limited. The simplified inter prediction may be a prediction that suggests the number of reference pictures for the target unit. The inter-prediction unit 110 can perform prediction on the target unit using a smaller reference picture for the dynamic unit for the static unit.

Alternatively, the simplified inter prediction may be a limited prediction of the inter prediction direction of the inter prediction. The simplified inter prediction may be a prediction with limited inter prediction direction for the target unit. The inter-prediction unit 110 can perform prediction on the target unit in the inter-prediction direction which is more limited than the dynamic unit for the static unit.

The inter-prediction unit 110 may perform prediction for a target unit using search ranges that are different from each other for a plurality of types.

For example, the simplified inter prediction may be a prediction in which a search is made in the reduced search area. The inter-prediction unit 110 can perform prediction on the target unit in the search area smaller than the dynamic unit for the static unit.

The above-described steps 810 and 820 may be performed in combination with the operations performed by other components of the encoding apparatus 110 described above with reference to FIG.

The inter-prediction unit by the inter-prediction unit 110 may be performed by the inter-prediction unit 250 of the decoding apparatus 200 as well. The above-described steps 810 and 820 may also be performed by the inter-prediction unit 250. [ In addition, the above-described steps 810 and 820 can be performed in combination with the operations performed by the other components of the decoding apparatus 200 described above with reference to Fig.

FIG. 9 shows a difference image between a current picture and a reference picture according to an example.

In Fig. 9, the current picture and two reference pictures are shown. The current picture may be a current picture to be currently encoded or decoded. The current picture may be a picture including the current block.

In Fig. 9, the LCU _CUR may represent the target unit. LCU _AL , LCU _A , LCU _AR, and LCU _L may represent restored neighboring units of the target unit.

There may be two reference picture lists L0 and L1 for the current picture. The first reference picture among the two reference pictures may be a picture selected at L0 and the second reference picture may be a picture selected at L1.

In Fig. 9, LCU ^L0 _CUR may represent the corresponding unit of the first reference picture. LCU ^L0 _AL , LCU _A ^L0, LCU ^L0 _AR and LCU ^L0 _L may represent reconstructed neighboring units of the corresponding unit of the first reference picture. The LCU ^L1 _CUR may represent the corresponding unit of the second reference picture. LCU ^L1 _AL , LCU _A ^L1, LCU ^L1 _AR and LCU ^L1 _L may represent reconstructed neighboring units of the corresponding unit of the second reference picture.

In Fig. 9, two difference images are shown. The difference image on the left side may be a difference image between the reference picture of L0 and the current picture. The difference image on the left side can represent the reference picture of L0 and the SAD of the current picture. The difference image on the right side may be a difference image between the reference picture of L1 and the current picture. And the difference image on the right side can indicate the reference picture of L1 and the SAD of the current picture.

As shown in the figure, the current picture may be composed of a plurality of CUs, and the encoding or decoding may be performed for each CU according to the raster scan order.

Generally, the CU of the difference image may have the following characteristics depending on the characteristics of the image.

1) When there is a moving object in the CU, the object boundary and the edge of the object mainly due to the change of the phase of the object with time difference and the detailed movement of the object. There may be (relatively larger) difference values in the regions. In FIG. 9, the portion denoted by "A " can represent the difference value generated in the object boundary and edge regions of the moving object.

2) When the CU exists in the static region, since there is no change in the characteristic (e.g., complexity) of the image according to the time difference, most pixel values (or difference values) Lt; / RTI > The portion indicated by "B" in FIG. 9 may indicate a region other than the portion indicated by "A", and may indicate a static region.

Based on the general phenomenon of the above-described image, the target unit can be classified as one of the static unit and the dynamic unit according to the characteristics of the image in the target unit.

For classification of the target unit, the inter-prediction unit 110 can calculate the error value in pixel units between the target unit of the current picture and the corresponding unit of the reference picture. The corresponding unit may be a call block in the reference picture.

The SAD described above with reference to FIG. 8 may be an example of an error value in pixel units. For example, in addition to the SAD, the error value may be another error value such as a Sum of Squared Error (SSE). In the embodiment described above with reference to Figure 8, the SAD can be replaced by a zero value or SSE.

The inter-prediction unit 110 may calculate the SAD of the target block based on Equation (2) below.

Here, k can represent a reference picture of L0 or a reference picture of L1. i can represent the x coordinate of the pixel. j may represent the y coordinate of the pixel. N can represent the size of the target unit.

Each CU of the current picture may have a "type_flag" of 1 bit. If the value of the SAD calculated for CU is greater than or equal to the predetermined SAD threshold (Th _SAD ), the CU may be determined as a dynamic unit. In this case, the value of the type flag may be set to "true "," logical 1 ", or a predefined first value. If the value of the SAD calculated for the CU exceeds the predefined SAD threshold Th _SAD ), the CU may be determined as a static unit. In this case, the value of the type flag "may be set to false "," logical 0 ", or a predefined second value.

10 shows type flags of a target unit and restored neighboring units according to an example.

In Fig. 10, the TF _CUR may indicate the "type flag" of the target unit. TF _AL may indicate a "type flag" of a neighboring unit adjacent to the upper left corner of the target unit. TF _A may indicate the "type flag" of the adjacent unit at the top of the target unit. TF _AR can indicate the "type flag" of the unit adjacent to the upper right of the target unit. TF _L may represent the "type flag" of a unit to the left of the target unit.

In addition to the aforementioned relatively simple determination of the type of the target unit, the inter-prediction unit 110 can provide a method of determining the type of a more reliable target unit by considering the degree of correlation between the adjacent units and the target unit.

For example, in a general natural image, when it is assumed that there is no camera movement, the static area existing in the background tends to appear over a wide range. Accordingly, in the determination of the type of the target unit, the type of the target unit may have a large correlation with the types of the predetermined adjacent units.

To account for this correlation, the inter-prediction unit 110 may calculate the weighted sum "flag_sum" of the "type_flag"

The inter-prediction unit 110 may calculate the weighted sum "flag_sum" of the target unit based on Equation (3) below.

TF _i may represent the "type_flag" of unit i. i represents the CUR representing the target unit, AL representing the upper left Above Left unit, A representing the Above adjacent unit, AR representing the Above Right adjacent unit, and Left adjacent unit L < / RTI > K may be the number of adjacent units available. w _i may be a weight of unit i.

The weights of the target unit and adjacent units may be different predetermined values. For example, the weight of TF _i may be determined as w _cur = 0.5, w _L = 0.2 and w _AL = w _A = w _AR = 0.1, assuming that the correlation between the target unit and the left adjacent unit is the highest. For example, a unit of a neighboring unit having a higher correlation with a target unit may have a higher weight.

The inter-prediction unit 110 can determine the final type of the target unit using the weighted sum "flag_sum ".

The inter-prediction unit 110 may determine the final type of the target unit based on Equation (4) below.

The "type_flag" may represent the final type of the target unit. Th may be a predetermined threshold.

When the slice type of the slice of the target unit is a non-slice (Bslice), the inter-prediction unit 110 can use the left reference picture and the right reference picture in determining the type of the target unit. The inter prediction unit 110 can calculate the SAD1 between the LCU of the target unit and the LCU of the corresponding unit of the left reference picture and calculate the SAD2 of the LCU of the LC unit of the target unit and the LCU of the corresponding unit of the right reference picture. Inter prediction unit 110 may use the average of SAD1 and SAD1 as the SAD for the target unit. The inter prediction unit 110 may calculate the SAD using the right-side arithmetic shift operation of 1 bit as shown in Equation (5) below.

When the SAD is calculated, the inter-prediction unit 110 can determine the TF of "type flae" of the target unit based on Equation (6) below.

As described above with reference to FIG. 3, when conventional inter prediction techniques are applied, each CU can be recursively partitioned up to a predetermined depth. At this time, the depth information can indicate the size of the CU and can be stored for each CU. For example, the depth of the LCU may be zero, and the depth of the SCU may be a predetermined maximum depth. When the CU is a static unit, the image represented by the CU is predominantly a homogeneous region or may have a gradually changing characteristic. Thus, CUs that are static units can be predominantly shown to be coded as large predictive units. When a conventional inter prediction technique is used, there is a possibility that the CU is encoded into a plurality of prediction blocks that are subdivided more than necessary.

When the CU is divided more than necessary, the coding efficiency can be reduced because the motion information must be transmitted to each lower prediction unit. In addition, the complexity of the encoding apparatus 100 can be increased because recursive partitioning and prediction for CUs must be performed up to the defined maximum depth.

The inter-prediction unit 110 may divide the target unit by applying a maximum depth different for the plurality of types according to the type of the target unit. Here, the inter-prediction unit 110 may set the maximum depth of the static unit among the plurality of types to be smaller than the maximum depth of the dynamic unit.

That is to say, the inter prediction unit 110 can cause the static unit to be encoded with only a prediction unit of a large size by decreasing the information of the maximum depth that has been set for division for the static unit. The inter prediction unit 110 can improve the coding efficiency and reduce the complexity of the coding apparatus 100 by causing the static unit to be coded only by a prediction unit having a large size.

For example, when the maximum depth for a recursive partition is N, the maximum depth for a static unit may be NL. Here, N may be an integer of 1 or more. L may be an integer of 0 or more and N1 or less. Alternatively, L may have a value between 1 and N.

The inter-prediction unit 110 may adaptively determine the value of L. [ For example, the inter-prediction unit 110 may determine the value of L based on the value of flag_sum in Equation (3). Under the assumption that all the weights the value of w _i 1, the value of L can be calculated as follows N (Mflag_sum). That is, L = N is established when the value of flag_sum is 5, L = N1 is established when the value of flag_sum is 4, and L = N2 when flag_sum is 3. Here, M may be the number of units used to calculate flag_sum, or the number of TF _i . For example, if adjacent units are an upper left adjacent unit, an upper adjacent unit, a right adjacent unit, and a left unit, the value of M may be 5.

When a conventional inter prediction technique is applied, the range of motion vector values can be determined by a predefined search range (SR). The actual information transmitted from the encoding apparatus 100 to the decoding apparatus 200 may be a motion vector difference (MVD) between a determined MV and an MV of an adjacent block.

In the case of the static unit, since the correlation with the adjacent block is high, the MV having a relatively small value tends to be determined. Therefore, by using the SR that is smaller than the defined SR for the static encoding unit, it is possible to reduce the complexity of the encoding apparatus 100 for motion prediction and reduce the transmission amount of the motion information, thereby improving the encoding efficiency.

For example, when the size of an SR determined for a general unit or a dynamic unit is N, the size of SR for a static unit may be NL. Here, N may be an integer of 2 or more. N may be an integer smaller than or equal to 1 and smaller than N.

The inter-prediction unit 110 may adaptively determine the value of L. [ For example, the inter-prediction unit 110 may determine the value of L based on the value of flag_sum in Equation (3). For example, the inter-prediction unit 110 can set the value of L to be larger as the value of flag_sum is larger. Under the assumption that all the weights the value of w _i 1, the value of L can be calculated as follows N (Mflag_sum). That is to say, if the value of flag_sum is 5, the value of L = can be 3 * N / 4. If the value of flag_sum is 4, the value of L may be N / 2. If the value of flag_sum is less than or equal to 3, the value of L may be N / 4.

11 is a structural diagram of an electronic apparatus for implementing an encoding apparatus and / or a decoding apparatus according to an embodiment.

The inter prediction unit 110, the intra prediction unit 120, the switch 115, the subtractor 125, the transform unit 130, the quantization unit 140, the entropy coding unit 140, At least some of the components 150, de-quantization unit 160, inverse transform unit 170, adder 175, filter unit 180 and reference picture buffer 190 may be program modules, Lt; / RTI > The program modules may be included in the encoding apparatus 100 in the form of an operating system, an application program module, and other program modules.

According to an embodiment of the present invention, the entropy decoding unit 210, the inverse quantization unit 220, the inverse transform unit 230, the intra prediction unit 240, the inter prediction unit 250, the adder 255 ), The filter unit 260, and the reference picture buffer 270 may be program modules and may communicate with an external device or system. The program modules may be included in the decryption apparatus 200 in the form of an operating system, an application program module, and other program modules.

The program modules may be physically stored on various known storage devices. At least some of these program modules may also be stored in a remote storage device capable of communicating with the encoding device 100 or a remote storage device capable of communicating with the decryption device 200. [

Program modules may be implemented as a set of routines, subroutines, programs, objects, components, and data that perform functions or operations in accordance with one embodiment, implement an abstract data type according to one embodiment, Data structures, and the like, but are not limited thereto.

The program modules may be comprised of at least one processor of the encoding apparatus 100 or an instruction or code executed by at least one processor of the decoding apparatus 200. [

The encoding device 100 and / or the decoding device 200 may be implemented as the electronic device 1100 shown in Fig. The electronic device 1100 may be a general-purpose computer system that operates as the encoding device 100 and / or the decryption device 200.

10, the electronic device 1100 includes at least one processing unit 1110, a memory 1130, a user interface (UI) input device A UI output device 1160, a UI output device 1160, and a storage 1140. The electronic device 1100 may further include a communication unit 1120 connected to the network 1199. The processing unit 1110 may be a semiconductor device that executes processing instructions stored in a central processing unit (CPU), memory 1130, or storage 1140. Memory 1130 and storage 1140 may be various types of volatile or non-volatile storage media. For example, the memory may include at least one of ROM (R) 1131 and RAM (RAM) 1132.

The encoding apparatus 100 and / or the decoding apparatus 200 can be implemented in a computer system including a recording medium that can be read by a computer.

The recording medium may store at least one module required for the electronic device 1100 to operate as the encoding device 100 and / or the decoding device 200. The memory 1130 may store at least one module and may be configured to be executed by at least one processing unit 1110. [

Functions related to the communication of data or information of the encoding apparatus 100 and / or the decoding apparatus 200 may be performed through the communication unit 1120. [

In the above-described embodiments, although the methods are described on the basis of a flowchart as a series of steps or units, the present invention is not limited to the order of the steps, and some steps may occur in different orders or simultaneously . It will also be understood by those skilled in the art that the steps depicted in the flowchart illustrations are not exclusive and that other steps may be included or that one or more steps in the flowchart may be deleted without affecting the scope of the invention You will understand.

The embodiments of the present invention described above can be implemented in the form of program instructions that can be executed through various computer components and recorded on a computer-readable recording medium. The computer-readable recording medium may include program commands, data files, data structures, and the like, alone or in combination. The program instructions recorded on the computer-readable recording medium may be those specially designed and constructed for the present invention or may be those known and used by those skilled in the computer software arts. Examples of the computer-readable recording medium include magnetic media such as a hard disk, a floppy disk and a magnetic tape, optical recording media such as CDROM and DVD, magnetooptical media such as a floptical disk, , RAM, flash memory, and the like, which are specifically configured to store and execute program instructions. Examples of program instructions include machine language code such as those generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules for performing the processing according to the present invention, and vice versa.

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, Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, I will say.

Claims (1)

Determining a type of the target unit based on the image complexity of the target unit; And
Performing inter-prediction on the target unit according to the determined type
Wherein the inter prediction method comprises:

Images