WO2020050705A1

WO2020050705A1 - Method of decoding and encoding image for processing group unit quantization parameter

Info

Publication number: WO2020050705A1
Application number: PCT/KR2019/011651
Authority: WO
Inventors: 임화섭; 임정윤
Original assignee: 가온미디어 주식회사
Priority date: 2018-09-07
Filing date: 2019-09-09
Publication date: 2020-03-12

Abstract

An image processing method according to an embodiment of the present invention comprises the steps of: dividing a picture of an image into a plurality of coding units each of which is a basic unit for which inter prediction or intra prediction is performed, and dividing the picture or each of the divided coding units in a quad tree, a binary tree, or a ternary tree structure to determine a target block for decoding the coding unit; and selectively and adaptively determining a quantization parameter for processing quantization of the target block on the basis of coding tree unit-based quantization group unit information including the target block.

Description

Image decoding and encoding method for processing group-level quantization parameters

The present invention relates to video encoding and decoding, and more particularly, to a method of performing prediction and quantization by dividing a video picture into a plurality of blocks.

In the image compression method, one picture is divided into a plurality of blocks having a predetermined size, and encoding is performed. In addition, inter prediction and intra prediction techniques that remove redundancy between pictures are used to increase compression efficiency.

In this case, a residual signal is generated using intra prediction and inter prediction, and the reason for obtaining the residual signal is that when coding with the residual signal, the amount of data is small, so the data compression rate is high, and the better the prediction, the better the residual signal. This is because the value of.

The intra prediction method predicts data of the current block using pixels around the current block. The difference between the actual value and the predicted value is called the residual signal block. In the case of HEVC, the intra prediction method increases from 9 prediction modes used in the existing H.264 / AVC to 35 prediction modes to further refine the prediction.

In the case of the inter prediction method, the current block is compared with blocks in neighboring pictures to find the most similar block. At this time, the location information (Vx, Vy) for the found block is called a motion vector. The difference of pixel values in a block between a current block and a prediction block predicted by a motion vector is called a residual signal block (motion-compensated residual block).

In this way, although intra prediction and inter prediction are further subdivided, the amount of data of the residual signal is decreasing, but the amount of computation for processing a video has increased significantly.

In particular, there are difficulties in implementing a pipeline due to an increase in complexity in the process of determining a split structure in a picture for image encoding and decoding, and the existing block splitting method and the size of the split block according to the existing block are high-resolution images. It may not be suitable for encoding.

In addition, due to the processing of ultra-high resolution images to support virtual reality, such as 360 VR images, and the processing of various divided structures accompanying it, the quantization processing process according to the current block structure may be inefficient.

The present invention is to solve the above problems, is suitable for encoding and decoding of high-resolution images, and the image processing method for processing a more efficient quantization process according to a complex encoding characteristic change, and an image decoding and encoding method using the same The purpose is to provide.

An image decoding method according to an embodiment of the present invention for solving the above problems, in the image decoding method, a picture is a plurality of basic units in which inter prediction or intra prediction is performed. Decoding the coding unit is divided into a coding unit (Coding Unit) of the picture or the divided coding unit into a quad tree (quad tree), binary tree (binary tree) or ternery tree (ternery tree) structure Determining a target block for; And selectively adaptively determining a quantization parameter according to the quantization process of the target block, based on the group quantization information of the target block.

In the image decoding apparatus according to an embodiment of the present invention for solving the above problems, in the image decoding method, a plurality of pictures are basic units in which inter prediction or intra prediction is performed. Decoding the coding unit is divided into a coding unit (Coding Unit) of the picture or the divided coding unit into a quad tree (quad tree), binary tree (binary tree) or ternery tree (ternery tree) structure A dividing unit for determining a target block for; And a characteristic adaptive quantization parameter determining unit selectively adaptively determining a quantization parameter according to the quantization process of the target block, based on the group quantization information of the target block.

In the video encoding method according to an embodiment of the present invention for solving the above problems, in the video encoding method, a plurality of pictures are basic units in which inter prediction or intra prediction is performed. Decoding the coding unit is divided into a coding unit (Coding Unit) of the picture or the divided coding unit into a quad tree (quad tree), binary tree (binary tree) or ternery tree (ternery tree) structure Determining a target block for; And selectively adaptively determining a quantization parameter according to the quantization process of the target block, based on the group quantization information of the target block.

According to an embodiment of the present invention, a coding unit, which is a basic unit in which inter prediction or intra prediction is performed, may be divided into a composite tree structure including a quad tree, a binary tree, and a ternary tree, and the target block group of the target block By selectively adaptively determining a quantization parameter according to the quantization process of the target block based on quantization information, quantization efficiency corresponding to a diversified block shape can be improved, and coding efficiency for a high-resolution image can be improved. .

In addition, according to an embodiment of the present invention, since the derivation process of the quantization parameter and the quantization parameter derived therefrom are selectively adaptively determined using the detailed characteristic information of the image, the motion compensation efficiency corresponding to the diversified block form and The filtering effect can be improved, and coding efficiency for a high resolution image can be improved.

1 is a block diagram showing the configuration of an image encoding apparatus according to an embodiment of the present invention.

2 to 5 are diagrams for describing a first embodiment of a method of dividing and processing an image in block units.

6 is a block diagram illustrating an embodiment of a method for performing inter prediction in an image encoding apparatus.

7 is a block diagram showing the configuration of an image decoding apparatus according to an embodiment of the present invention.

8 is a block diagram illustrating an embodiment of a method of performing inter prediction in an image decoding apparatus.

9 is a view for explaining a second embodiment of a method of dividing and processing an image in block units.

10 is a diagram illustrating an embodiment of a syntax structure used to process an image by dividing it into blocks.

11 is a diagram for describing a third embodiment of a method of dividing and processing an image in block units.

12 is a diagram for explaining an embodiment of a method of configuring a transformation unit by dividing a coding unit into a binary tree structure.

13 is a view for explaining a fourth embodiment of a method of dividing and processing an image in block units.

14 to 16 are diagrams for explaining other embodiments of a method of dividing and processing an image in block units.

17 and 18 are diagrams for explaining embodiments of a method of determining a split structure of a transform unit by performing rate distortion optimization (RDO).

19 is a view for explaining a composite partition structure according to another embodiment of the present invention.

20 is a block diagram illustrating a quantization unit according to an embodiment of the present invention in more detail.

21 is a diagram for explaining a characteristic adaptive quantization parameter determiner according to an embodiment of the present invention in more detail.

22 is a flowchart illustrating a process of determining an initial quantization parameter corresponding to a CTU group unit according to an embodiment of the present invention.

23 is a view for explaining that an initial quantization parameter is determined for each group quantization unit according to an embodiment of the present invention.

24 is a flowchart illustrating a decoding method for processing inverse quantization according to an embodiment of the present invention.

25 is a view for explaining slice type based quantization parameter derivation according to an embodiment of the present invention.

26 is a flowchart illustrating an entire process according to an embodiment of the present invention.

27 to 29 are diagrams for explaining a high level syntax according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In describing the embodiments of the present specification, when it is determined that detailed descriptions of related known configurations or functions may obscure the subject matter of the present specification, detailed descriptions thereof will be omitted.

When a component is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but other components may exist in the middle. It should be. In addition, the description of "including" a specific configuration in the present invention does not exclude configurations other than the configuration, and means that additional configurations may be included in the scope of the present invention or the technical spirit of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component.

In addition, the components shown in the embodiments of the present invention are shown independently to indicate different characteristic functions, and do not mean that each component is composed of separate hardware or one software component. That is, for convenience of description, each component is listed and included as each component, and at least two components of each component are combined to form one component, or one component is divided into a plurality of components to perform functions. The integrated and separated embodiments of the components are also included in the scope of the present invention without departing from the essence of the present invention.

Also, some of the components are not essential components for performing essential functions in the present invention, but may be optional components for improving performance. The present invention can be implemented by including only components necessary for realizing the essence of the present invention, except for components used for performance improvement, and structures including only essential components excluding optional components used for performance improvement. Also included in the scope of the present invention.

1 is a block diagram showing the configuration of an image encoding apparatus according to an embodiment of the present invention. The image encoding apparatus 10 includes a picture splitter 110, a transform unit 120, a quantization unit 130, and scanning. The unit 131, the entropy encoding unit 140, the intra prediction unit 150, the inter prediction unit 160, the inverse quantization unit 135, the inverse transform unit 125, the post-processing unit 170, the picture storage unit 180 ), A subtracting unit 190 and an adding unit 195.

Referring to FIG. 1, the picture splitter 110 analyzes an input video signal, divides a picture into coding units, determines a prediction mode, and determines the size of a prediction unit for each coding unit.

Also, the picture splitter 110 sends the prediction unit to be encoded to the intra prediction unit 150 or the inter prediction unit 160 according to a prediction mode (or prediction method). Also, the picture splitter 110 sends a prediction unit to be encoded to the subtractor 190.

Here, a picture of an image may be composed of a plurality of bricks, tiles, or slices, and the bricks, tiles, or slices are a plurality of coding tree units, which are basic units for dividing a picture ( Coding Tree Unit (CTU).

Accordingly, each tile, brick, or slice may form a CTU group unit described according to an embodiment of the present invention.

For example, the tile may be a rectangular CTU unit partition defined by rows and columns, and the brick may be a rectangular partition composed of CTU row units or a substructure included in a specific tile. Further, a slice may be composed of an integer number of bricks formed continuously, and configuration information may be exclusively included in one network abstraction layer unit (NAL unit). Here, the slice may include one or more entire tiles, or may include only consecutive bricks included in one tile.

For example, by the picture dividing unit 110, one picture may be divided into a plurality of bricks, which are rectangular regions of a CTU row group, and the picture includes the bricks and is divided into one or more columns. It may be divided into tiles, divided into tiles including the bricks and divided into one or more horizontal columns, or divided into tiles including the bricks and divided into one or more vertical columns and one or more horizontal columns. The picture may be equally divided into tiles of the same size based on the lengths of the horizontal and vertical columns in the picture, or may be divided into tiles of different sizes.

The coding tree unit may be divided into one or two or more coding units (CUs), which are basic units in which inter prediction or intra prediction is performed.

The coding unit CU may be divided into one or more prediction units (PUs), which are basic units for which prediction is performed.

In this case, the encoding apparatus 10 determines one of inter prediction and intra prediction for each of the divided coding units (CUs) as a prediction method, but differently predicts blocks for each prediction unit (PU). Can be created.

Meanwhile, the coding unit CU may be divided into one or two or more transform units (TUs), which are basic units for transforming a residual block.

In this case, the picture division unit 110 may transmit the image data to the subtraction unit 190 in a block unit (eg, a prediction unit (PU) or a transformation unit (TU)) divided as described above.

Referring to FIG. 2, a coding tree unit (CTU) having a maximum size of 256x256 pixels is divided into a quad tree structure, and may be divided into four coding units (CUs) having a square shape.

Each of the four coding units (CUs) having the square shape may be re-divided into a quad tree structure, and the depth (Depth) of the coding unit (CU) divided into a quad tree structure may be 0 to 3 as described above. It can have one integer value.

The coding unit CU may be divided into one or two or more prediction units PU according to a prediction mode.

In the case of the intra prediction mode, when the size of the coding unit CU is 2Nx2N, the prediction unit PU may have the size of 2Nx2N shown in FIG. 3A or NxN shown in FIG. 3B. have.

On the other hand, in the case of the inter prediction mode, when the size of the coding unit CU is 2Nx2N, the prediction unit PU is 2Nx2N shown in FIG. 4A, 2NxN shown in FIG. 4B, and FIG. 4B Nx2N shown in (c), NxN shown in FIG. 4 (d), 2NxnU shown in FIG. 4 (e), 2NxnD shown in FIG. 4 (f), and shown in FIG. 4 (g) It may have a size of any one of nLx2N and nRx2N shown in Figure 4 (h).

Referring to FIG. 5, the coding unit (CU) is divided into a quad tree structure, and can be divided into four transform units (TUs) having a square shape.

The four transform units (TUs) having the square shape may be re-divided into quad tree structures, and the depth (Depth) of the transform unit (TU) divided into quad tree structures may be 0 to 3 as described above. It can have one integer value.

Here, when the coding unit CU is in the inter prediction mode, the prediction unit PU and the transform unit TU split from the corresponding coding unit CU may have independent splitting structures.

When the coding unit CU is an intra prediction mode, the transform unit TU divided from the coding unit CU cannot be larger than the size of the prediction unit PU.

In addition, the conversion unit (TU) divided as described above may have a maximum size of 64x64 pixels.

The conversion unit 120 converts the residual block, which is a residual signal between the original block of the input prediction unit PU and the prediction block generated by the intra prediction unit 150 or the inter prediction unit 160, wherein the conversion is conversion The unit TU may be performed as a basic unit.

During the transformation process, different transformation matrices may be determined according to a prediction mode (intra or inter), and since the residual signal of intra prediction has directionality according to the intra prediction mode, the transformation matrix may be adaptively determined according to the intra prediction mode. have.

The transformation unit may be transformed by two (horizontal, vertical) one-dimensional transformation matrices, for example, in the case of inter prediction, one predetermined transformation matrix may be determined.

On the other hand, in the case of intra prediction, when the intra prediction mode is horizontal, since the probability of a residual block having directionality in the vertical direction increases, a DCT-based integer matrix is applied in the vertical direction, and DST-based or in the horizontal direction. Apply KLT-based integer matrix. When the intra prediction mode is vertical, a DST-based or KLT-based integer matrix may be applied in the vertical direction, and a DCT-based integer matrix may be applied in the horizontal direction.

In addition, in the DC mode, a DCT-based integer matrix can be applied to both directions.

And, in the case of intra prediction, a transform matrix may be adaptively determined based on the size of the transform unit (TU).

The quantization unit 130 determines a quantization step size for quantizing the coefficients of the residual block transformed by the transform matrix, and the quantization step size may be determined for each quantization unit having a predetermined size or more.

The size of the quantization unit may be 8x8 or 16x16, and the quantization unit 130 quantizes coefficients of a transform block using a quantization matrix determined according to a quantization step size and a prediction mode.

Also, the quantization unit 130 may use a quantization step size of a quantization unit adjacent to the current quantization unit as a quantization step size predictor of the current quantization unit.

The quantization unit 130 may search the left quantization unit, the upper quantization unit, and the left upper quantization unit of the current quantization unit to generate a quantization step size predictor of the current quantization unit using one or two valid quantization step sizes. have.

For example, the quantization unit 130 may determine a valid first quantization step size retrieved in the order as a quantization step size predictor, or determine an average value of two valid quantization step sizes retrieved in the order as a quantization step size predictor, or If only one quantization step size is valid, it can be determined as a quantization step size predictor.

When the quantization step size predictor is determined, the quantization unit 130 transmits the difference between the quantization step size of the current quantization unit and the quantization step size predictor to the entropy encoding unit 140.

Meanwhile, all of the left coding unit, the upper coding unit, and the left upper coding unit of the current coding unit do not exist. Alternatively, there may be previously existing coding units in the coding order in the largest coding unit.

Accordingly, quantization units adjacent to the current coding unit and the quantization step size of the previous quantization unit in the coding order may be candidates in the largest coding unit.

In this case, priority is set in the order of 1) the left quantization unit of the current coding unit, 2) the upper quantization unit of the current coding unit, 3) the upper left quantization unit of the current coding unit, and 4) the order of the previous quantization unit in the coding order. Can be. The order may be changed, and the upper left quantization unit may be omitted.

Meanwhile, the quantized transform block as described above is transferred to the inverse quantization unit 135 and the scanning unit 131.

The scanning unit 131 scans the coefficients of the quantized transform block and converts them into one-dimensional quantized coefficients. In this case, since the coefficient distribution of the transform block after quantization may depend on the intra prediction mode, the scanning method is based on the intra prediction mode. It can be decided accordingly.

Also, the coefficient scanning method may be differently determined according to the size of the transform unit, and the scan pattern may be changed according to the directional intra prediction mode, and in this case, the scan order of the quantization coefficients may be scanned in the reverse direction.

When the quantized coefficients are divided into a plurality of subsets, the same scan pattern may be applied to quantization coefficients in each subset, and a zigzag scan or diagonal scan may be applied to the scan pattern between subsets.

Meanwhile, the scan pattern is preferably scanned from the main subset including DC to the remaining subsets in the forward direction, but the reverse direction is also possible.

Also, a scan pattern between subsets may be set in the same manner as the scan pattern of quantized coefficients in the subset, and the scan pattern between subsets may be determined according to the intra prediction mode.

On the other hand, the encoding apparatus 10 includes a decoding apparatus by including in the bitstream information indicating the position of the last non-zero quantization coefficient and the position of the last non-zero quantization coefficient in each subset in the transform unit (PU) ( 20).

The inverse quantization unit 135 inverse quantizes the quantized quantized coefficients as described above, and the inverse transform unit 125 performs inverse transformation in units of transform units (TU) to restore the inverse quantized transform coefficients to a residual block in a spatial domain. can do.

The adder 195 may generate a reconstructed block by combining the residual block reconstructed by the inverse transform unit 125 with the predicted block received from the intra predictor 150 or the inter predictor 160.

In addition, the post-processing unit 170 deblocking filtering process to remove the blocking effect occurring in the reconstructed picture, sample adaptive offset (Sample Adaptive Offset: to compensate for the difference value from the original image in units of pixels) SAO) application process and a coding unit can perform post-processing such as an adaptive loop filtering (ALF) process to compensate for a difference value from the original image.

The deblocking filtering process may be applied to a boundary of a prediction unit (PU) or a transform unit (TU) having a size equal to or greater than a predetermined size.

For example, the deblocking filtering process may include determining a boundary to be filtered, determining a boundary filtering strength to be applied to the boundary, and determining whether to apply a deblocking filter, If it is determined to apply the deblocking filter, it may include selecting a filter to be applied to the boundary.

On the other hand, whether or not the deblocking filter is applied includes i) whether the boundary filtering intensity is greater than 0, and ii) the degree of change in pixel values at the boundary of two block (P block, Q block) adjacent to the boundary to be filtered. It may be determined by whether the value indicated is smaller than the first reference value determined by the quantization parameter.

It is preferable that at least two said filters. When the absolute value of the difference value between two pixels located at the block boundary is greater than or equal to the second reference value, a filter that performs relatively weak filtering is selected.

The second reference value is determined by the quantization parameter and the boundary filtering intensity.

In addition, the sample adaptive offset (SAO) application process is to reduce the difference (distortion) between the pixel and the original pixel in the image to which the deblocking filter is applied, and the sample adaptive offset (SAO) application process is performed in units of pictures or slices. It can be decided whether or not to perform.

The picture or slice may be divided into a plurality of offset areas, and an offset type may be determined for each offset area, wherein the offset type is a predetermined number (eg, 4) edge offset types and 2 band offsets. Type.

For example, when the offset type is an edge offset type, an edge type to which each pixel belongs is determined and an offset corresponding thereto is applied, and the edge type may be determined based on a distribution of two pixel values adjacent to the current pixel. have.

The adaptive loop filtering (ALF) process may perform filtering based on a value obtained by comparing a reconstructed image and an original image that have undergone a deblocking filtering process or an adaptive offset application process.

The picture storage unit 180 receives the post-processed image data from the post-processing unit 170 and restores and stores the image in picture units, and the picture may be a frame unit image or a field unit image.

The inter prediction unit 160 may perform motion estimation using at least one reference picture stored in the picture storage unit 180 and determine a reference picture index and a motion vector indicating the reference picture.

In this case, a prediction block corresponding to a prediction unit to be encoded may be extracted from a reference picture used for motion estimation among a plurality of reference pictures stored in the picture storage unit 180 according to the determined reference picture index and motion vector. have.

The intra prediction unit 150 may perform intra prediction encoding using reconstructed pixel values inside a picture in which the current prediction unit is included.

The intra prediction unit 150 may receive the current prediction unit to be predictively encoded and select one of a preset number of intra prediction modes according to the size of the current block to perform intra prediction.

The intra prediction unit 150 adaptively filters the reference pixel to generate the intra prediction block, and when the reference pixel is not available, the reference pixels may be generated using the available reference pixels.

The entropy encoding unit 140 may entropy encode quantization coefficients quantized by the quantization unit 130, intra prediction information received from the intra prediction unit 150, and motion information received from the inter prediction unit 160. .

FIG. 6 is a block diagram showing an embodiment of a configuration in which the encoding apparatus 10 performs inter prediction, and the illustrated inter prediction encoder is a motion information determination unit 161 and a motion information encoding mode determination unit 162. , A motion information encoding unit 163, a prediction block generation unit 164, a residual block generation unit 165, a residual block encoding unit 166, and a multiplexer 167.

Referring to FIG. 6, the motion information determination unit 161 determines motion information of a current block, motion information includes a reference picture index and a motion vector, and the reference picture index is any one of pictures that have been previously encoded and reconstructed. Can represent

If the current block is one-way inter-prediction coded, it indicates any one of the reference pictures belonging to list 0 (L0), and when the current block is two-way predictive-coded, it refers to one of the reference pictures in list 0 (L0). An index and a reference picture index indicating one of the reference pictures of list 1 (L1) may be included.

In addition, when the current block is bidirectionally predictively coded, an index indicating one or two pictures of reference pictures of the composite list LC generated by combining list 0 and list 1 may be included.

The motion vector indicates a position of a prediction block in a picture indicated by each reference picture index, and the motion vector may be a pixel unit (integer unit) or a sub pixel unit.

For example, the motion vector may have a precision of 1/2, 1/4, 1/8, or 1/16 pixels, and when the motion vector is not an integer unit, a prediction block is generated from pixels of the integer unit. You can.

The motion information encoding mode determiner 162 may determine an encoding mode for motion information of a current block, and the encoding mode may be exemplified as one of a skip mode, a merge mode, and an AMVP mode.

The skip mode is applied when there is a skip candidate having the same motion information as the motion information of the current block, and the residual signal is 0. In the skip mode, the current block, which is the prediction unit (PU), is the size of the coding unit (CU). Can be applied when is equal.

The merge mode is applied when there is a merge candidate having the same motion information as the motion information of the current block, and the merge mode has a residual signal when the size of the current block is different from the coding unit (CU) or the same size. In case it applies. Meanwhile, the merge candidate and the skip candidate may be the same.

The AMVP mode is applied when the skip mode and the merge mode are not applied, and an AMVP candidate having a motion vector most similar to the motion vector of the current block can be selected as the AMVP predictor.

However, the encoding mode is a process other than the above-described method, and may include a more fine-grained motion compensation prediction encoding mode. The adaptively determined motion compensation prediction mode includes the above-described AMVP mode, merge mode, and skip mode, as well as FRUC (FRAME RATE UP-CONVERSION) mode, BIO (BI-DIRECTIONAL OPTICAL FLOW), which is currently proposed as a new motion compensation prediction mode. ) Mode, AMP (AFFINE MOTION PREDICTION) mode, OBMC (OVERLAPPED BLOCK MOTION COMPENSATION) mode, DMVR (DECODER-SIDE MOTION VECTOR REFINEMENT) mode, ATMVP (Alternative temporal motion vector prediction) mode, STMVP (Spatial-temporal motion vector prediction) Mode, and may further include at least one of LIC (Local Illumination Compensation) mode, it can be determined block adaptively according to a predetermined condition.

The motion information encoding unit 163 may encode motion information according to a method determined by the motion information encoding mode determiner 162.

For example, the motion information encoding unit 163 may perform a merge motion vector encoding process when the motion information encoding mode is a skip mode or a merge mode, and may perform an AMVP encoding process in the AMVP mode.

The prediction block generation unit 164 generates a prediction block using motion information of the current block, and when the motion vector is an integer unit, copies a block corresponding to a position indicated by the motion vector in the picture indicated by the reference picture index and copies the current block To generate predictive blocks.

Meanwhile, when the motion vector is not an integer unit, the prediction block generator 164 may generate pixels of the prediction block from integer unit pixels in the picture indicated by the reference picture index.

In this case, a prediction pixel may be generated using an 8-tap interpolation filter for a luminance pixel, and a prediction pixel may be generated using a 4-tap interpolation filter for a chrominance pixel.

The residual block generator 165 generates a residual block using the current block and the prediction block of the current block, and when the size of the current block is 2Nx2N, the residual block is generated using the 2Nx2N prediction block corresponding to the current block and the current block You can create blocks.

On the other hand, when the size of the current block used for prediction is 2NxN or Nx2N, after obtaining a prediction block for each of the 2 2NxN blocks constituting 2Nx2N, a final prediction block of 2Nx2N size is obtained by using the 2 2NxN prediction blocks. Can be created.

In addition, a 2Nx2N size residual block may be generated using the 2Nx2N size prediction block, and overlap smoothing may be applied to pixels of the boundary part to resolve discontinuity of the boundary part of the 2 prediction blocks having 2NxN size. You can.

The residual block encoder 166 divides the residual block into one or more transform units (TUs), so that each transform unit (TU) can be transform-encoded, quantized, and entropy-encoded.

The residual block encoder 166 may transform the residual block generated by the inter prediction method using an integer-based transform matrix, and the transform matrix may be an integer-based DCT matrix.

Meanwhile, the residual block encoder 166 uses a quantization matrix to quantize the coefficients of the residual block transformed by the transform matrix, and the quantization matrix can be determined by a quantization parameter.

The quantization parameter is determined for each coding unit (CU) having a predetermined size or more, and if the current coding unit (CU) is smaller than the predetermined size, the first coding unit (in coding order) among coding units (CU) within the predetermined size ( Only the quantization parameter of CU) is coded, and the quantization parameter of the remaining coding unit CU is the same as the above parameter, and thus may not be coded.

Also, coefficients of the transform block may be quantized using a quantization matrix determined according to the quantization parameter and a prediction mode.

The quantization parameter determined for each coding unit (CU) having a predetermined size or more may be predictively coded using the quantization parameter of the coding unit (CU) adjacent to the current coding unit (CU).

It is possible to generate a quantization parameter predictor of the current coding unit (CU) by searching in the order of the left coding unit (CU) and the upper coding unit (CU) of the current coding unit (CU) and using one or two valid quantization parameters. have.

For example, a valid first quantization parameter retrieved in the above order may be determined as a quantization parameter predictor, and a valid first quantization parameter may be quantized by searching in the order of the left coding unit (CU) and the previous coding unit (CU) in the coding order. It can be determined as a parameter predictor.

The coefficients of the quantized transform block are scanned and converted into one-dimensional quantized coefficients, and the scanning method may be set differently according to the entropy coding mode.

For example, when encoded with CABAC, inter-prediction-encoded quantization coefficients can be scanned in one predetermined manner (zigzag, or raster scan in a diagonal direction), and when encoded with CAVLC, scanning in a different way from the above method Can be.

For example, the scanning method may be determined according to a zigzag case in the case of inter and an intra prediction mode in case of intra, and the coefficient scanning method may be differently determined according to the size of a transform unit.

Meanwhile, the scan pattern may vary according to the directional intra prediction mode, and the scan order of quantization coefficients may be scanned in the reverse direction.

The multiplexer 167 multiplexes the motion information encoded by the motion information encoding unit 163 and the residual signals encoded by the residual block encoding unit 166.

The motion information may vary according to an encoding mode, and for example, in the case of skip or merge, only the index indicating the predictor may be included, and in the case of AMVP, the reference picture index, the differential motion vector, and the AMVP index of the current block may be included. .

Hereinafter, an embodiment of the operation of the intra prediction unit 150 illustrated in FIG. 1 will be described in detail.

First, the intra prediction unit 150 receives the prediction mode information and the size of the prediction unit PU from the picture division unit 110, and the picture storage unit determines a reference pixel to determine the intra prediction mode of the prediction unit PU It can be read from 180.

The intra prediction unit 150 determines whether a reference pixel is generated by examining whether there is an unavailable reference pixel, and the reference pixels can be used to determine an intra prediction mode of the current block.

When the current block is located at the upper boundary of the current picture, pixels adjacent to the upper side of the current block are not defined, and when the current block is located at the left boundary of the current picture, pixels adjacent to the left of the current block are not defined, It may be determined that the pixels are not available pixels.

In addition, it may be determined that the current block is located at the slice boundary and pixels adjacent to the upper or left side of the slice are not available pixels even if the pixels are not encoded and reconstructed first.

As described above, when pixels adjacent to the left or upper side of the current block do not exist, or pixels that have been pre-encoded and reconstructed do not exist, the intra prediction mode of the current block may be determined using only available pixels.

Meanwhile, a reference pixel at a location that is not available may be generated using the available reference pixels of the current block. For example, when the pixels of the upper block are not available, the upper pixel may be used using some or all of the left pixels. You can create them, and vice versa.

That is, a reference pixel is generated by copying an available reference pixel at a location closest to a predetermined direction from a reference pixel at a location that is not available, or when there is no reference pixel available in a predetermined direction, the closest in the opposite direction A reference pixel may be generated by copying the available reference pixel of the position.

On the other hand, even when the upper or left pixels of the current block exist, it may be determined as a reference pixel that is not available according to an encoding mode of a block to which the pixels belong.

For example, when a block to which the reference pixel adjacent to the upper side of the current block belongs is an inter-coded and reconstructed block, the pixels may be determined as unavailable pixels.

In this case, available reference pixels may be generated using pixels belonging to a reconstructed block in which a block adjacent to the current block is intra coded, and information indicating that the encoding apparatus 10 determines available reference pixels according to an encoding mode. It is transmitted to the decoding device 20.

The intra prediction unit 150 determines the intra prediction mode of the current block using the reference pixels, and the number of intra prediction modes allowable for the current block may vary according to the size of the block.

For example, 34 intra prediction modes may exist when the size of the current block is 8x8, 16x16, and 32x32, and 17 intra prediction modes may exist when the size of the current block is 4x4.

The 34 or 17 intra prediction modes may be composed of at least one non-directional mode (non-directional mode) and a plurality of directional modes (directional modes).

The one or more non-directional modes may be DC mode and / or planar mode. When the DC mode and the planner mode are included as a non-directional mode, 35 intra prediction modes may exist regardless of the size of the current block.

In this case, two non-directional modes (DC mode and planner mode) and 33 directional modes may be included.

In the planner mode, at least one pixel value (or a prediction value of the pixel value, hereinafter referred to as a first reference value) and a reference pixel positioned at a bottom-right of the current block is used to predict the prediction block of the current block. Is generated.

The configuration of the video decoding apparatus according to an embodiment of the present invention may be derived from the configuration of the video encoding apparatus 10 described with reference to FIGS. 1 to 6, for example, as described with reference to FIGS. 1 to 6. An image can be decoded by inversely performing the processes of the same image encoding method.

7 is a block diagram showing the configuration of a video decoding apparatus according to an embodiment of the present invention, the decoding apparatus 20 includes an entropy decoding unit 210, an inverse quantization / inverse transformation unit 220, an adder 270, It has a post-processing unit 250, a picture storage unit 260, an intra prediction unit 230, a motion compensation prediction unit 240, and an intra / inter switch 280.

The entropy decoding unit 210 receives and decodes the encoded bit stream from the image encoding apparatus 10, separates it into intra prediction mode indexes, motion information, and quantization coefficient sequences, and decodes the decoded motion information into a motion compensation prediction unit ( 240).

The entropy decoding unit 210 transmits the intra prediction mode index to the intra prediction unit 230 and the inverse quantization / inverse transformation unit 220 to transmit the inverse quantization coefficient sequence to the inverse quantization / inverse transformation unit 220.

The inverse quantization / inverse transform unit 220 converts the quantization coefficient sequence into an inverse quantization coefficient in a two-dimensional array, and can select one of a plurality of scanning patterns for the conversion, for example, a prediction mode (ie, a current block) (Intra prediction or inter prediction) and an intra prediction mode.

The inverse quantization / inverse transform unit 220 restores a quantization coefficient by applying a quantization matrix selected from a plurality of quantization matrices to an inverse quantization coefficient of a two-dimensional array.

Meanwhile, different quantization matrices are applied according to the size of the current block to be reconstructed, and a quantization matrix may be selected for a block having the same size based on at least one of the prediction mode and the intra prediction mode of the current block.

The inverse quantization / inverse transform unit 220 inversely transforms the reconstructed quantization coefficient to restore a residual block, and the inverse transform process may be performed using a transform unit (TU) as a basic unit.

The adder 270 reconstructs the image block by combining the residual block reconstructed by the inverse quantization / inverse transform unit 220 and the prediction block generated by the intra prediction unit 230 or the motion compensation prediction unit 240.

The post-processing unit 250 may perform post-processing on the reconstructed image generated by the adder 270 to reduce deblocking artifacts and the like due to image loss due to quantization by filtering or the like.

The picture storage unit 260 is a frame memory for storing a local decoded image in which filter post-processing is performed by the post-processing unit 250.

The intra prediction unit 230 restores the intra prediction mode of the current block based on the intra prediction mode index received from the entropy decoding unit 210 and generates a prediction block according to the restored intra prediction mode.

The motion compensation prediction unit 240 generates a prediction block for a current block from a picture stored in the picture storage unit 260 based on the motion vector information, and applies a selected interpolation filter to apply the selected interpolation filter when motion compensation with a decimal precision is applied. You can create

The intra / inter switch 280 may provide the adder 270 with a prediction block generated by any one of the intra prediction unit 230 and the motion compensation prediction unit 240 based on the encoding mode.

8 is a block diagram showing an embodiment of a configuration for performing inter prediction in the video decoding apparatus 20, the inter prediction decoder is a demultiplexer 241, a motion information encoding mode determination unit 242, a merge mode motion The information decoding unit 243, the AMVP mode motion information decoding unit 244, the selection mode motion information decoding unit 248, the prediction block generation unit 245, the residual block decoding unit 246 and the reconstructed block generation unit 247 It includes.

Referring to FIG. 8, the de-multiplexer 241 demultiplexes the currently encoded motion information and the encoded residual signals from the received bitstream, and transmits the demultiplexed motion information to the motion information encoding mode determination unit 242 Then, the demultiplexed residual signal may be transmitted to the residual block decoder 246.

The motion information encoding mode determining unit 242 determines the motion information encoding mode of the current block, and when the skip_flag of the received bitstream has a value of 1, the motion information encoding mode of the current block is determined to be encoded in the skip encoding mode can do.

When the skip_flag of the received bitstream has a value of 0 and the motion information received from the de-multiplexer 241 has only a merge index, the motion information encoding mode determining unit 242 is a motion information encoding mode of the current block It can be determined that is encoded in the merge mode.

In addition, the motion information encoding mode determining unit 242 has a value of 0 for skip_flag of the received bitstream, and motion information received from the demultiplexer 241 has a reference picture index, a differential motion vector, and an AMVP index. In this case, it may be determined that the motion information encoding mode of the current block is encoded in the AMVP mode.

The merge mode motion information decoding unit 243 is activated when the motion information encoding mode determining unit 242 determines the current block motion information encoding mode as skip or merge mode, and the AMVP mode motion information decoding unit 244 moves It may be activated when the information encoding mode determining unit 242 determines the current block motion information encoding mode as the AMVP mode.

The selection mode motion information decoding unit 248 may decode motion information in a prediction mode selected from among other motion compensation prediction modes except for the above-described AMVP mode, merge mode, and skip mode. The selective prediction mode may include a more precise motion prediction mode compared to the AMVP mode, and may be determined block-adaptively according to predetermined conditions (eg, block size and block segmentation information, signaling information existence, block position, etc.). . Selective prediction mode is, for example, FRUC (FRAME RATE UP-CONVERSION) mode, BIO (BI-DIRECTIONAL OPTICAL FLOW) mode, AMP (AFFINE MOTION PREDICTION) mode, OBMC (OVERLAPPED BLOCK MOTION COMPENSATION) mode, DMVR (DECODER-SIDE) It may include at least one of a MOTION VECTOR REFINEMENT mode, an ATMVP (Alternative temporal motion vector prediction) mode, a STMVP (Spatial-temporal motion vector prediction) mode, and a LIC (Local Illumination Compensation) mode.

The prediction block generator 245 generates a prediction block of the current block by using the motion information restored by the merge mode motion information decoder 243 or the AMVP mode motion information decoder 244.

When the motion vector is an integer unit, a block corresponding to a position indicated by the motion vector in the picture indicated by the reference picture index may be copied to generate a prediction block of the current block.

Meanwhile, when the motion vector is not an integer unit, pixels of a prediction block are generated from integer unit pixels in a picture indicated by a reference picture index. In this case, an 8-tap interpolation filter is used for a luminance pixel and a color difference pixel Prediction pixels may be generated using a 4-tap interpolation filter.

The residual block decoder 246 entropy-decodes the residual signal and inversely scans the entropy-decoded coefficients to generate a two-dimensional quantized coefficient block, and the inverse scanning method may vary according to the entropy decoding method.

For example, the inverse scanning method may be applied in a diagonal raster inverse scanning method when decoded based on CABAC or in a zigzag inverse scan method when decoded based on CAVLC. Also, the inverse scanning method may be differently determined according to the size of the prediction block.

The residual block decoding unit 246 may inverse quantize the coefficient block generated as described above using an inverse quantization matrix, and reconstruct a quantization parameter to derive the quantization matrix. Here, the quantization step size may be restored for each coding unit having a predetermined size or more.

The residual block decoding unit 260 inversely transforms the inverse-quantized coefficient block to restore the residual block.

The reconstructed block generator 270 generates a reconstructed block by adding the predicted block generated by the predicted block generator 250 and the residual block generated by the residual block decoder 260.

Hereinafter, an embodiment of a process of restoring a current block through intra prediction will be described with reference to FIG. 7 again.

First, the intra prediction mode of the current block is decoded from the received bitstream, and for that purpose, the entropy decoding unit 210 restores the first intra prediction mode index of the current block by referring to one of the plurality of intra prediction mode tables. You can.

As a table shared by the plurality of intra prediction mode tables encoding apparatus 10 and decoding apparatus 20, any one table selected according to the distribution of intra prediction modes for multiple blocks adjacent to the current block may be applied. .

For example, if the intra prediction mode of the left block of the current block and the intra prediction mode of the upper block of the current block are the same, the first intra prediction mode table is applied to restore the index of the first intra prediction mode of the current block, and is not the same. Otherwise, the first intra prediction mode index of the current block may be restored by applying the second intra prediction mode table.

As another example, when the intra prediction mode of the upper block and the left block of the current block are both directional intra prediction modes, the direction of the intra prediction mode of the upper block and the intra prediction mode of the left block If it is within a predetermined angle, the first intra prediction mode index of the current block is restored by applying the first intra prediction mode table, and if it is outside the predetermined angle, the second intra prediction mode table is applied to the first intra prediction mode index of the current block. Can also be restored.

The entropy decoding unit 210 transmits the first intra prediction mode index of the restored current block to the intra prediction unit 230.

When the index has a minimum value (ie, 0), the intra prediction unit 230 receiving the index of the first intra prediction mode may determine the maximum possible mode of the current block as the intra prediction mode of the current block. .

Meanwhile, when the index has a value other than 0, the intra prediction unit 230 compares the index indicated by the maximum possible mode of the current block with the index of the first intra prediction mode, and as a result of the comparison, the first intra prediction mode If the index is not smaller than the index indicated by the maximum possible mode of the current block, the intra prediction mode corresponding to the second intra prediction mode index obtained by adding 1 to the first intra prediction mode index is determined as the intra prediction mode of the current block. Otherwise, the intra prediction mode corresponding to the first intra prediction mode index may be determined as the intra prediction mode of the current block.

The intra prediction mode allowable for the current block may include at least one non-directional mode (non-directional mode) and a plurality of directional modes (directional modes).

The one or more non-directional modes may be DC mode and / or planar mode. In addition, either the DC mode or the planner mode may be adaptively included in the allowable intra prediction mode set.

To this end, information specifying a non-directional mode included in the allowable intra prediction mode set may be included in a picture header or a slice header.

Next, the intra prediction unit 230 reads the reference pixels from the picture storage unit 260 to generate an intra prediction block, and determines whether there is an unavailable reference pixel.

The determination may be made according to the presence or absence of reference pixels used to generate an intra prediction block by applying the decoded intra prediction mode of the current block.

Next, when it is necessary to generate the reference pixel, the intra prediction unit 230 may generate reference pixels at a location that is not available using previously reconstructed available reference pixels.

The definition of a reference pixel that is not available and the method of generating the reference pixel may be the same as the operation of the intra prediction unit 150 according to FIG. 1, but an intra prediction block is generated according to the decoded intra prediction mode of the current block. The reference pixels used for this may be selectively restored.

In addition, the intra prediction unit 230 determines whether to apply a filter to reference pixels to generate a prediction block, that is, whether to apply filtering to reference pixels to generate an intra prediction block of the current block. It can be determined based on the decoded intra prediction mode and the size of the current prediction block.

The problem of blocking artifacts increases as the size of the block increases, so as the size of the block increases, the number of prediction modes for filtering the reference pixel can be increased, but if the block becomes larger than a predetermined size, it can be seen as a flat area, reducing complexity. For example, the reference pixel may not be filtered.

When it is determined that a filter needs to be applied to the reference pixel, the intra prediction unit 230 filters the reference pixels using a filter.

At least two or more filters may be adaptively applied according to the difference in the level difference between the reference pixels. The filter coefficient of the filter is preferably symmetrical.

In addition, the above two or more filters may be adaptively applied according to the size of the current block. When applying a filter, a filter having a narrow bandwidth for a small block and a filter having a wide bandwidth for a large block May be applied.

In the DC mode, since a prediction block is generated with the average value of the reference pixels, there is no need to apply a filter, and in a vertical mode where correlations are different in the vertical direction, there is no need to apply a filter to the reference pixels, and the image is horizontal. Even in a horizontal mode that is related in the direction, it may not be necessary to apply a filter to a reference pixel.

As described above, whether or not filtering is applied is also related to the intra prediction mode of the current block, so that the reference pixel can be filtered adaptively based on the intra prediction mode of the current block and the size of the prediction block.

Next, the intra prediction unit 230 generates a prediction block using reference pixels or filtered reference pixels according to the restored intra prediction mode, and generation of the prediction block is the same as that of the operation of the encoding apparatus 10. Since it can be, a detailed description thereof will be omitted.

The intra prediction unit 230 determines whether to filter the generated prediction block, and the filtering may be determined by using information included in a slice header or a coding unit header or according to an intra prediction mode of the current block.

When it is determined that the generated prediction block is to be filtered, the intra prediction unit 230 may generate a new pixel by filtering a pixel at a specific position of the generated prediction block using available reference pixels adjacent to the current block. .

For example, in the DC mode, a prediction pixel contacting the reference pixels among the prediction pixels may be filtered using a reference pixel contacting the prediction pixel.

Accordingly, the prediction pixel is filtered using one or two reference pixels according to the position of the prediction pixel, and filtering of the prediction pixel in DC mode can be applied to prediction blocks of all sizes.

Meanwhile, in the vertical mode, prediction pixels in contact with the left reference pixel among the prediction pixels of the prediction block may be changed using reference pixels other than the upper pixel used to generate the prediction block.

Similarly, in the horizontal mode, prediction pixels that come into contact with the upper reference pixel among the generated prediction pixels may be changed using reference pixels other than the left pixel used to generate the prediction block.

In this way, the current block may be reconstructed using the prediction block of the current block reconstructed and the residual block of the decoded current block.

9 is a diagram for describing a second embodiment of a method of dividing and processing an image in block units.

Referring to FIG. 9, a coding tree unit (CTU) having a maximum size of 256x256 pixels is first divided into a quad tree structure, and can be divided into four coding units (CUs) having a square shape.

Here, at least one of the coding units divided into the quad tree structure is divided into a binary tree structure, and may be re-divided into two coding units (CUs) having a rectangular shape.

Meanwhile, at least one of the coding units divided into the quad tree structure may be divided into a quad tree structure and re-divided into four coding units (CUs) having a square shape.

In addition, at least one of the coding units re-divided into the binary tree structure may be divided into a binary tree structure and divided into two coding units (CUs) having a square or rectangular shape.

Meanwhile, at least one of the coding units re-divided into the quad tree structure may be divided into a quad tree structure or a binary cree structure, and may be divided into coding units (CUs) having a square or rectangular shape.

CUs configured by being divided into a binary tree structure as described above are not split anymore and can be used for prediction and transformation. In this case, the binary partitioned CU may include a coding block (CB) that is a block unit that performs actual sub / decoding and syntax corresponding to the corresponding coding block. That is, the size of the prediction unit PU and the transformation unit TU belonging to the coding block CB as shown in FIG. 9 may be the same as the size of the corresponding coding block CB.

The coding unit split into the quad tree structure may be divided into one or more prediction units (PUs) using the method as described with reference to FIGS. 3 and 4.

In addition, the coding unit divided into a quad tree structure may be divided into one or two or more transform units (TUs) using the method as described with reference to FIG. 5, and the split transform unit (TU) Can have a maximum size of 64x64 pixels.

10 illustrates an embodiment of a syntax structure used to process an image by dividing it into blocks.

10 and 9, a block structure according to an embodiment of the present invention may be determined through split_cu_flag indicating whether to split a quad tree and binary_split_flag indicating whether to split a binary tree.

For example, whether to split the coding unit (CU) as described above may be indicated using split_cu_flag. In addition, binary_split_flag indicating whether to split or not and syntax indicating the split direction may be determined in correspondence to a binary partitioned CU after quad tree splitting. At this time, as a method of indicating the directionality of binary splitting, a method of determining a splitting direction based on this by decoding a plurality of syntaxes such as binary_split_hor and binary_split_ver, or decoding a single syntax and signal values according to it, such as binary_split_mode, and Horizontal (0) Alternatively, a method of processing division in the vertical (1) direction may be exemplified.

As another embodiment according to the present invention, the depth of a coding unit (CU) split using a binary tree may be represented using binary_depth.

1 to 8 for blocks (eg, a coding unit (CU), a prediction unit (PU), and a transform unit (TU)) divided by a method as described with reference to FIGS. 9 and 10. By applying the methods as described above, encoding and decoding of an image may be performed.

Hereinafter, another embodiment of a method of dividing a coding unit (CU) into one or two or more transform units (TUs) will be described with reference to FIGS. 11 to 16.

According to an embodiment of the present invention, the coding unit (CU) may be divided into a binary tree structure and divided into transform units (TUs), which are basic units for transforming residual blocks.

For example, referring to FIG. 11, at least one of rectangular coding blocks CU ₀ and Cu ₁ divided into a binary tree structure and having a size of Nx2N or 2NxN is divided into a binary tree structure, and the size of NxN It can be divided into square transform units (TU ₀ , TU ₁ ).

As described above, the block-based image encoding method may perform prediction, transform, quantization, and entropy encoding steps.

In the prediction step, a prediction signal is generated by referring to a block performing current encoding and an existing coded image or a surrounding image, and through this, a difference signal from the current block can be calculated.

On the other hand, in the conversion step, the difference signal is used as input to perform conversion using various conversion functions, and the converted signal is classified into DC coefficients and AC coefficients to be energy compacted to improve encoding efficiency. You can.

In addition, in the quantization step, quantization is performed with transform coefficients as an input, and then entropy encoding is performed on the quantized signal, so that an image may be encoded.

On the other hand, the image decoding method proceeds in the reverse order of the encoding process as described above, and an image quality distortion phenomenon may occur in the quantization step.

As a method for reducing the image distortion while improving the encoding efficiency, the size or shape of the transform unit (TU) and the type of transform function applied can be varied according to the distribution of the difference signal input to the input in the transform step and the characteristics of the image. have.

For example, when a block similar to the current block is found through a block-based motion estimation process in a prediction step, a difference is measured using a cost measurement method such as SAD (Sum of Absolute Difference) or MSE (Mean Square error). Signal distribution can occur in various forms depending on the characteristics of the image.

Accordingly, efficient encoding can be performed by selectively performing the transformation by determining the size or shape of the transformation unit CU based on the distribution of various difference signals.

Referring to FIG. 12, when a differential signal is generated as shown in (a) in any coding unit (CUx), the coding unit (CUx) is divided into a binary tree structure as shown in (b) 2 By dividing into two transform units (TUs), an effective transform can be performed.

For example, since it can be said that the DC value generally represents the average value of the input signal, when a differential signal as shown in (a) of FIG. 12 is received as the input of the conversion process, two coding units (CUx) are used. By dividing into conversion units (TUs), it is possible to effectively represent the DC value.

Referring to FIG. 13, a square coding unit (CU ₀ ) having a size of 2Nx2N is divided into a binary tree structure, and can be divided into rectangular transform units (TU ₀ and TU ₁ ) having a size of Nx2N or 2NxN. .

According to another embodiment of the present invention, as described above, the step of dividing the coding unit (CU) into a binary tree structure may be performed repeatedly two or more times, and divided into a plurality of transform units (TUs).

Referring to FIG. 14, a rectangular coding block (CB ₁ ) having a size of Nx2N is divided into a binary tree structure, and a block having the size of the divided NxN is further divided into a binary tree structure to N / 2xN or NxN / After constructing a rectangular block having a size of 2, the block having the size of N / 2xN or NxN / 2 is divided into a binary tree structure, and square transform units having a size of N / 2xN / 2 (TU ₁ , TU ₂ , TU ₄ , TU ₅ ).

Referring to FIG. 15, a square coding unit (CU ₀ ) having a size of 2Nx2N is divided into a binary tree structure, and a block having the size of the divided Nx2N is divided into a binary tree structure, and a square having a size of NxN is obtained. After constructing the block of, the block having the size of NxN may be further divided into a binary tree structure and divided into rectangular transform units (TU ₁ and TU ₂ ) having the size of N / 2xN.

Referring to FIG. 16, a rectangular coding unit (CU ₀ ) having a size of 2NxN is divided into a binary tree structure, and a block having the size of the divided NxN is divided into a quad tree structure to generate N / 2xN / 2. It can be divided into square transform units having a size (TU ₁ , TU ₂ , TU ₃ , TU ₄ ).

1 to 8 for blocks (eg, a coding unit (CU), a prediction unit (PU), and a transform unit (TU)) divided by a method as described with reference to FIGS. 11 to 16. By applying the methods as described above, encoding and decoding of an image may be performed.

Hereinafter, embodiments of a method of determining a block division structure by the encoding apparatus 10 according to the present invention will be described.

The picture dividing unit 110 provided in the image encoding apparatus 10 performs rate distortion optimization (RDO) according to a preset order, and as described above, the dividable coding unit (CU), prediction unit (PU), and transform The division structure of the unit TU can be determined.

For example, in order to determine the block division structure, the picture division unit 110 determines an optimal block division structure in terms of bitrate and distortion while performing rate distortion optimization-quantization (RDO-Q). You can.

Referring to FIG. 17, when the coding unit CU has a form of 2Nx2N pixel size, 2Nx2N pixel size shown in (a), NxN pixel size shown in (b), and Nx2N pixel size shown in (c) , RD may be performed in the order of 2NxN pixel sized conversion unit (PU) split structure shown in (d) to determine the optimal split structure of the transform unit (PU).

Referring to FIG. 18, when the coding unit CU has a form of Nx2N or 2NxN pixel size, the pixel size of Nx2N (or 2NxN) shown in (a), the pixel size of NxN shown in (b), Pixel size of N / 2xN (or NxN / 2) and NxN shown in (c), N / 2xN / 2, N / 2xN and pixel size of NxN shown in (d), N shown in (e) It is possible to determine the optimal division structure of the conversion unit PU by performing RDO in the order of the division structure of the conversion unit (PU) having a pixel size of / 2xN.

In the above, the block division method of the present invention has been described as an example in which a block division structure is determined by performing rate distortion optimization (RDO), but the picture division unit 110 has a Sum of Absolute Difference (SAD) or Mean Square Error (MSE). ), It is possible to maintain a proper efficiency while reducing the complexity by determining the block division structure.

According to an embodiment of the present invention, whether to apply adaptive loop filtering (ALF) in units of a coding unit (CU), a prediction unit (PU), or a transformation unit (TU) divided as described above is determined. You can.

For example, whether to apply the adaptive loop filter (ALF) may be determined on a coding unit (CU) basis, and the size or coefficient of a loop filter to be applied may vary according to the coding unit (CU).

In this case, information indicating whether to apply the adaptive loop filter (ALF) for each coding unit (CU) may be included in each slice header.

In the case of a chrominance signal, it may be determined whether to apply an adaptive loop filter (ALF) on a picture-by-picture basis, and the shape of the loop filter may have a rectangular shape unlike luminance.

In addition, the adaptive loop filtering (ALF) may determine whether to apply for each slice. Accordingly, information indicating whether adaptive loop filtering (ALF) is applied to the current slice may be included in a slice header or a picture header.

If it is indicated that adaptive loop filtering is applied to the current slice, the slice header or picture header may additionally include information indicating the filter length in the horizontal and / or vertical direction of the luminance component used in the adaptive loop filtering process.

The slice header or the picture header may include information indicating the number of filter sets, and when the number of filter sets is 2 or more, filter coefficients may be encoded using a prediction method.

Therefore, the slice header or the picture header may include information indicating whether filter coefficients are encoded by a prediction method, and when the prediction method is used, may include predicted filter coefficients.

Meanwhile, not only luminance but also chrominance components can be adaptively filtered. In this case, information indicating whether each chrominance component is filtered may be included in a slice header or a picture header, and for Cr and Cb to reduce the number of bits. Joint coding (ie, multiplexing coding) may be performed together with information indicating whether to filter.

At this time, in the case of chrominance components, since it is most likely that both Cr and Cb are not filtered to reduce complexity, entropy coding is performed by assigning the smallest index when both Cr and Cb are not filtered. can do.

In addition, when filtering both Cr and Cb, entropy coding may be performed by assigning the largest index.

Referring to FIG. 19, as the coding unit CU is divided into a binary tree structure, a rectangle having a shape in which the horizontal length W as shown in FIG. 19 (A) is longer than the vertical length H, and a vertical length as shown in FIG. 19 (B). The shape of the coding unit (CU) in which H is divided into a rectangle having a shape longer than the width W may appear. In the case of a coding unit having a long length in a specific direction as described above, it is highly likely that the encoding information is concentrated in the left and right or upper and lower edge regions compared to the middle region.

Therefore, for more precise and efficient encoding and decoding, the encoding apparatus 10 according to an exemplary embodiment of the present invention can facilitate the edge area of a coding unit, which has a long specific direction, by splitting quad trees and binary trees. The coding unit can be split into a ternary tree or triple tree structure that can be split.

For example, FIG. 19 (A) shows a first area of the left edge having a horizontal W / 8 and a vertical H / 4 length, and a horizontal W / 8 * 6, vertical when the coding unit to be divided is a horizontally divided coding unit. As the H / 4 length, it is shown that the second region, which is the middle region, and the third region of the right edge of the horizontal W / 8 and the vertical H / 4 length can be struck.

19 (B), when the coding unit to be divided is a vertically divided coding unit, a first region of a top edge having a horizontal W / 4 and a vertical H / 8 length, and a horizontal W / 4 and a vertical H / 8 * It is shown that the length can be divided into a second region, which is an intermediate region, and a third region of the lower edge of the horizontal W / 4 and the vertical H / 8 length.

In addition, the encoding apparatus 10 according to an embodiment of the present invention may process the splitting of the ternary tree structure through the picture splitter 110. To this end, the picture divider 110 may not only determine the division into the above-described quad-tree and binary-tree structures according to encoding efficiency, but may also fine-tune the segmentation scheme by considering the ternary tree structure together.

Here, the division of the ternary tree structure may be processed for all coding units without limitation. However, considering the encoding and decoding efficiency as described above, it may be desirable to allow a ternary tree structure only for coding units having specific conditions.

In addition, the ternary tree structure may require ternary division of various methods for the coding tree unit, but it may be desirable to allow only an optimized predetermined form in consideration of encoding and decoding complexity and transmission bandwidth by signaling.

Therefore, in determining the division of the current coding unit, the picture division unit 110 may determine and determine whether to divide the current coding unit into a ternary tree structure of a specific type only when the preset coding condition is met. In addition, according to the allowance of such a ternary tree, the split ratio of the binary tree can be extended and varied to 3: 1, 1: 3, etc., not only 1: 1. Accordingly, the splitting structure of the coding unit according to the embodiment of the present invention may include a composite tree structure that is subdivided into quad trees, binary trees, or ternary trees according to ratios.

For example, the picture division unit 110 may determine a complex division structure of the coding unit to be divided based on the division table.

According to an embodiment of the present invention, the picture dividing unit 110 processes quad-tree splitting and quad-tree-divided in response to a maximum size of a block (eg, pixel-based 128 x 128, 256 x 256, etc.) It is possible to perform a complex partitioning process that processes at least one of a dual tree structure and a triple tree structure partition corresponding to the terminal node.

In particular, according to an embodiment of the present invention, the picture partitioning unit 110 may include a first binary partition (BINARY 1) and a second binary partition (BINARY 2) that are binary tree partitions corresponding to characteristics and sizes of a current block according to a partition table. ) And a first ternary partition (TRI 1) or a second ternary partition (TRI 2), which is a ternary tree partition, may be determined.

Here, the first binary division may correspond to a vertical or horizontal division having a ratio of N: N, and the second binary division may correspond to a vertical or horizontal division having a ratio of 3N: N or N: 3N, and each The binary partitioned root CU may be divided into CU0 and CU1 of each size specified in the partition table.

Meanwhile, the first ternary division may correspond to a vertical or horizontal division having a ratio of N: 2N: N, and the second ternary division may correspond to a vertical or horizontal division having a ratio of N: 6N: N, and each The ternary partitioned root CU may be divided into CU0, CU1, and CU2 of each size specified in the partition table.

Accordingly, in accordance with the size of the coding unit to be divided, a partition table indicating each processable partitioning structure and a coding unit size in the case of partitioning may be determined.

However, the picture division unit 110 according to an embodiment of the present invention, the maximum coding unit size and the minimum coding unit size for applying the first binary division, the second binary division, the first ternary division or the second ternary division Can be set respectively.

This is because it may be inefficient in terms of complexity to perform encoding and decoding processing corresponding to a block having a minimum size, for example, 2 or less horizontal or vertical pixels, and accordingly, the partition table according to an embodiment of the present invention The allowable splitting structure for each size of each coding unit may be predefined.

Accordingly, the picture dividing unit 110 may prevent a case in which the horizontal or vertical pixel size is divided into 2 as a minimum size, for example, a size of less than 4, and for this purpose, the size of the block to be divided Determine whether the first binary partition, the second binary partition, the first ternary partition or the second ternary partition is allowed, and compare the RDO performance operation corresponding to the allowable partitioning structure to determine the optimal partitioning structure. You can.

For example, when the largest sized root coding unit CU 0 is binary-divided, the binary dividing structure may be divided into CU0 and CU1 constituting any one of 1: 1, 3: 1, or 1: 3 vertical partitioning. The ternary division structure may be divided into CU0, CU1, and CU2 constituting either one of 1: 2: 1 or 1: 6: 1 vertical division.

In particular, depending on the size of the coding unit to be divided, an allowable vertical division structure may be limitedly determined. For example, the vertical division structure of the 64X64 coding unit and the 32X32 coding unit may allow all of the first binary division, the second binary division, the first ternary division and the second ternary division, but among the vertical division structures of the 16X16 coding unit. The second strikeout division may be limited to impossible. Also, in the vertical division structure of the 8X8 coding unit, only the first binary division may be limitedly allowed. Thus, partitioning into blocks below the minimum size that causes complexity can be prevented in advance.

Similarly, when the largest sized root coding unit CU 0 is binary-divided, the binary-divided structure may be divided into CU0 and CU1 constituting any one of 1: 1, 3: 1, or 1: 3 horizontal divisions, The ternary division structure may be divided into CU0, CU1 and CU2 constituting either one of 1: 2: 1 or 1: 6: 1 horizontal division.

Likewise, according to the size of a coding unit to be divided, an allowable horizontal division structure may be limitedly determined. For example, the horizontal division structure of the 64X64 coding unit and the 32X32 coding unit may allow all of the first binary division, the second binary division, the first ternary division and the second ternary division, but among the horizontal division structures of the 16X16 coding unit The second strikeout division may be limited to impossible. Also, in the horizontal division structure of the 8X8 coding unit, only the first binary division may be limitedly permitted. Thus, partitioning into blocks below the minimum size that causes complexity can be prevented in advance.

On the other hand, a division form in the case where horizontal division corresponding to a vertically divided coding unit is processed may also be illustrated.

In this case, the picture dividing unit 110 horizontally processes the coding unit vertically divided into the first binary division or the second binary division, or horizontally divides the first ternary division or the second ternary division according to the division table. You can.

For example, corresponding to a coding unit vertically divided into 32X64, the picture division unit 110 divides into CU0 and CU1 of 32X32 according to the first binary division, or CX and CU1 of 32X48 and 32X16 according to the second binary division. In accordance with the first ternary division, 32X32, 32X16, 32X16 CU0, CU1, CU2, or according to the second ternary division 32X8, 64X48, 32X8 CU0, CU1, CU2.

Also, the picture splitter 110 may vertically process the horizontally divided coding unit as the first binary split or the second binary split, or vertically split the first split or the second ternary split.

For example, corresponding to a coding unit horizontally divided into 32X16, the picture division unit 110 may be divided into CU0 and CU1 of 16X16 according to the first binary division, or C0 and CU1 of 24X16 8X16 according to the second binary division. According to the first ternary division, it may be divided into CU0, CU1, CU2 of 8X16, 16X16, 8X16, or divided into CU0, CU1, CU2 of 4X16, 24X16, 4X16 according to the second ternary division.

The partitioning allowable structure may be conditionally determined differently for each CTU size, CTU group unit, and slice unit, and vertical and horizontal directions, such that the first binary partition, the second binary partition, the first ternary partition, and the second ternary partition When processing, each CU partition ratio and decision size information may be defined by a partition table, or condition information may be set in advance.

According to the division processing, by allowing conditional division using a binary tree and a ternary tree, division of an appropriate ratio according to characteristics of the coding unit is possible, and thus encoding efficiency can be improved.

As the block division structure according to an embodiment of the present invention is complex and diversified, the encoding and decoding process according to an embodiment of the present invention also corresponds to a coding tree unit (CTU) -based quantization group unit block for accurate and efficient prediction And a selective adaptive quantization parameter determination and quantization process.

The quantization parameter determination and quantization process may be performed by a specific configuration of the quantization unit 130 as illustrated in FIG. 20, and the operation of the quantization unit 130 in both the encoding and decoding processes according to an embodiment of the present invention And processing can be performed.

In particular, the quantization unit 130 may selectively adaptively determine a quantization parameter according to the quantization process of the target block, based on the quantization group unit information of the quantization target block.

To this end, the quantization unit 130 according to an embodiment of the present invention includes an initial quantization parameter derivation unit 1310, a characteristic adaptive quantization parameter determination unit 1320, a group unit difference quantization parameter derivation unit 1330, and coding block unit adaptation. And an enemy quantization parameter application unit 1340.

First, the initial quantization parameter deriving unit 1310 derives an initial quantization parameter (QUANTIZATION PARAMETER, QP) corresponding to each unit block. According to an embodiment of the present invention, the initial quantization parameter may be determined for each quantization group unit block corresponding to a CTU unit in a slice, and the initial quantization parameter derivation unit 1310 may include an initial quantization parameter determined for the quantization group unit block. A list of quantization parameter (INITIAL QP) may be set in advance, and the initial quantization parameter list may be updated based on the determined difference quantization parameter (DELTA QP) value.

The quantization unit block may be determined corresponding to blocks grouped within a CTU unit in one slice, and the initial quantization parameter derivation unit 1310 may determine detailed initial quantization parameters for each unit. Accordingly, according to an embodiment of the present invention, an initial quantization parameter corresponding to at least one of a temporal spatial region (REGION) of a picture such as a VR image, or a subpicture, tile, slice in a picture, or the CTU-based quantization group unit Can be determined. The initial quantization parameter derivation unit 1310 may construct an initial quantization parameter list based on the determined initial quantization parameter, and perform update processing corresponding thereto.

21 is a flowchart illustrating an operation of the initial quantization parameter derivation unit 1310 according to an embodiment of the present invention.

Referring to FIG. 21, the initial quantization parameter derivation unit 1310 according to an embodiment of the present invention first determines a division unit and a CTU quantization group region (S1001).

For example, the initial quantization parameter derivation unit 1310 may determine a division unit and a CTU quantization group region based on image characteristics and picture division information obtained from the division unit 110.

Thereafter, the initial quantization parameter derivation unit 1310 configures an initial QP list based on the determined division unit and quantization group unit region (S1003).

Then, the initial quantization parameter deriving unit 1310 derives an offset value based on the initial QP index of the configured initial QP list (S1005).

Then, the initial quantization parameter derivation unit 1310 sets an initial QP corresponding to the determined division unit and CTU-based quantization group unit region, respectively (S1007).

For example, referring to FIG. 22, in initial parameter determination of a quantization parameter according to an embodiment of the present invention, an initial quantization parameter for each slice unit may be determined, and initial quantization for each CTU group unit included in the slice unit The parameter may be determined as a value corresponding to the index.

Accordingly, the differential quantization parameter may also determine the differential quantization parameter for each slice unit and the differential quantization parameter for each CTU quantization group unit, and the differential quantization parameter for each CTU quantization group unit may be identified by a separate CTU QP index value. Can be processed.

FIG. 22 illustrates that as the QP for each CTU quantization group unit in one slice is determined, the difference QP value is also updated, and the initial quantization parameter derivation unit 1310 lists a quantization parameter list for updating the difference quantization parameter. It can be configured, and the difference quantization parameter value in the corresponding slice may be determined for each CTU-based quantization group unit such as CTU Delta QP list = {Delta_QP_A, Delta_QP_B, Delta_QP_C, Delta_QP_D}.

For each CTU, the CTU QP index may be allocated in the form of = {0, 1, 2, 3, ...}, and in FIG. 22, CTU Group A = 0, CTU Group B = 1, CTU Group = 2, CTU Group C = 3 can be mapped.

Accordingly, the initial quantization parameter derivation unit 1310 may calculate the initial CTU quantization parameter for each CTU unit block, corresponding to the QP value allocated for the entire slice and the determined CTU quantization unit block, and the initial CTU QP is , initial CTU QP = init_qp_minus26 + slice_qp_delta + 26 + CTU Delta QP List [CTU QP index].

On the other hand, Figure 23 shows the operation of the initial quantization parameter derivation unit 1310 for calculating the subdivided initial QP value for each CTU quantization unit block. First, the initial quantization parameter derivation unit 1310 uses PPS (PICTURE) from the header information of the image. PARAMETER SET) is parsed (S1011), and an initial QP value corresponding to the picture division unit is derived (S1013).

Thereafter, the initial quantization parameter deriving unit 1310 obtains slice header information from the header information, derives a slice delta QP that is a difference value, and calculates an initial slice QP value for each slice unit based on the slice delta QP (S1017). .

Thereafter, the initial quantization parameter derivation unit 1310 according to an embodiment of the present invention determines a CTU quantization unit division, derives a CTU delta QP list for updating a difference value (S1019), and each CTU quantization unit corresponding thereto A CTU delta QP index for each block is determined (S1021).

Thereafter, the initial quantization parameter derivation unit 1310 may generate and update an initial quantization parameter list for each CTU quantization unit block by deriving an initial CTU QP value based on the CTU delta QP index for each CTU quantization unit block (S1023). have.

Meanwhile, when the initial QP list for each CTU quantization unit block is determined, the characteristic adaptive quantization parameter determiner 1320 selectively updates and adapts a process for quantization parameter values corresponding to each CTU quantization group unit block and processes according to the image characteristics. It is possible to determine the quantization parameter accordingly, and it can be determined for each CTU quantization group unit block.

For example, the characteristic adaptive quantization parameter determiner 1320 may set a quantization step size (QP STEP SIZE) and a quantization range (QP RANGE) for each CTU quantization group unit according to the determined process.

Then, the characteristic adaptive quantization parameter determining unit 1320 sets the quantization step size (QP STEP SIZE) and quantization range (QP RANGE) for each CTU quantization group unit corresponding to the initial quantization parameter determined by the initial quantization parameter derivation unit 1310. By setting, it is possible to determine the final quantization parameter corresponding to this. The determined quantization parameter value may be transmitted to the group-level difference quantization parameter derivation unit 1330.

24 illustrates the characteristic adaptive quantization parameter determiner 1320 in more detail. Referring to FIG. 24, the characteristic adaptive quantization parameter determiner 1320, an image case-based quantization parameter derivation unit 1321, slices A selection adaptive quantization parameter determination process may be processed by including at least one of a type-based quantization parameter derivation unit 1323, a color sample-based quantization parameter derivation unit 1325, and a transform coefficient-based quantization parameter derivation unit 1327.

First, the image case-based quantization parameter derivation unit 1321 may determine a process for deriving quantization parameters for each case according to input image characteristics. Depending on the derivation process, the quantization step size and QP range can be determined for each case.

Here, each case (CASE) may be illustrated as follows.

CASE 1: When the input image is composed of Original Picture;

CASE 2: When the input image is a multi-view image or multiple images for each synchronized area are merged into one input image; EX) VR video such as Cube Map / ERP

CASE 3: When a single picture is divided into a plurality of input video segmentation units by slice / tile / region, etc .;

First, the image case-based quantization parameter derivation unit 1321 determines different quantization step sizes and QP ranges for Case 2 and Case 3 for each subregion REGION corresponding to a user's viewpoint in each division unit or a picture division unit. It can be processed to apply the Initial QP and update accordingly.

For example, the image case-based quantization parameter derivation unit 1321, in applying the initial QP, determines different quantization step sizes and QP ranges for each CTU quantization group unit in the slice initial QP value, and thus delta QP By processing to be applied, various offset values corresponding to regions divided in one input image may be processed.

More specifically, the image case-based quantization parameter derivation unit 1321 may store delta QPs corresponding to each split unit image as a list corresponding to CTU quantization group units. And, the delta QPs can be matched to the offset in the list, and index values are assigned for each offset, which can be used to distinguish each other.

In this case, according to a CTU quantization group unit list or a list index thereof, the image case-based quantization parameter derivation unit 1321 derives the offset value as a delta value for adjusting the initial QP in the slice, or the CTU quantization group unit. The corresponding delta QP (CTU_dQP) value can be derived directly. Accordingly, the image case-based quantization parameter derivation unit 1321 may process different quantization step sizes and QP ranges between units of each CTU quantization group, even if they are within one picture, and calculate an Initial QP value.

In addition, the image case-based quantization parameter derivation unit 1321 determines the CTU quantization group unit for adjusting the initial quantization parameter value based on the image case, and the quantization step size and QP range are determined for each group, and separately The delta QP value can be processed to be updated as an offset value.

In addition, the video case-based quantization parameter deriving unit 1321 configures an initial QP list for each CTU quantization group unit that can be applied for each CTU based on each video characteristic case, and each delta QP corresponding to the index of the list. You can handle the process of deriving the offset value.

Here, the image case-based quantization parameter derivation unit 1321 may set in advance the quantization step size and QP range and the number and size of QPs of the corresponding CTU quantization group unit or CTU_Initial_QP_List using slice header information or picture header information. .

As another example, the video case-based quantization parameter derivation unit 1321 may include video header information of a video parameter set (VPS), sequence parameter set (SPS), or a type of video encoded from a separate SEI message and a projection format. Alternatively, it is possible to derive flag information or the like that can identify it. In operation 1321, the encoded image may be determined using the corresponding encoding information, and an initial quantization parameter according to a picture division unit (eg, a sub picture or a CTU group unit) may be set.

The initial QP information of the header information set as described above may be inserted into, for example, a PPS or a sequence parameter set (SPS), and the characteristic adaptive quantization parameter determination unit 1320 is included in the PPS or SPS as described above. By using the coding parameters for each CTU-based quantization group unit, it is possible to selectively adaptively determine different Initial QP parameters for each CTU quantization group unit, even within one picture.

In more detail, the encoding parameter may include information on an encoding region (picture division region, picture division boundary, tile boundary, slice boundary, lower picture region and boundary) divided within one picture.

Then, the image case-based quantization parameter derivation unit 1321 corresponds to the Initial QP List set in the initial quantization parameter derivation unit 1310 to adjust the initial QP between the divided regions, and divides it by adjusting the offset value for each index of the list Initial QP for each CTU quantization group unit in a region may be adjusted.

At this time, the image case-based quantization parameter derivation unit 1321 sets the maximum size of the Initial QP List, or according to a predefined Default value or Defined value between the encoding device 100 and the decoding device 200, to the initial QP list. Corresponding QP list update processing can be performed.

Meanwhile, the slice type-based quantization parameter deriving unit 1323 may apply the quantization parameter differently according to the slice type to which the CTU quantization group unit belongs. For example, the slice type may be an I / B / P type slice, and prediction and transform results may be differently generated according to the slice type.

Therefore, the slice type-based quantization parameter derivation unit 1323 according to an embodiment of the present invention adaptively determines different quantization parameters corresponding to slice type-based prediction and transformation results for each CTU quantization unit block, from a cognitive quality point of view. Can improve the coding efficiency.

More specifically, for example, the slice type-based quantization parameter derivation unit 1323 first determines the set value (quantization step size and QP range) of the quantization parameter and performs the quantization process accordingly, firstly slices the CTU quantization unit block. Judge.

In addition, the slice type-based quantization parameter derivation unit 1323, in the case of I Slice, the allowable prediction in the slice may be limited to intra-prediction, so a predefined quantization step size and QP range corresponding to the intra-prediction process Can decide.

In addition, in the case of P Slice, uni-directional prediction may be allowed in intra-screen prediction and inter-screen prediction, and a predefined quantization step size and QP range are determined in response to the intra-screen prediction process and uni-directional prediction of inter-screen prediction. You can.

In addition, in the case of B Slice, intra-prediction, uni-directional prediction in inter-prediction, bi-directional prediction, or prediction with reference to a plurality of reference pictures are all possible, and pre-defined quantization corresponding to a case that allows the multiple prediction The step size and QP range can be determined.

As described above, according to the slice type, a prediction method may be limited, and this may affect an RDO process for determining a block partitioning structure. Therefore, the slice type based quantization parameter derivation unit 1323 according to an embodiment of the present invention, Coding and decoding efficiency can be improved by subdividing and determining an efficient quantization step size and QP range corresponding to each CTU quantization unit block.

On the other hand, the residual signal by the prediction (Residual) is the input of the transform (Transform) process, it may affect the transform function mode and transform coefficients.

Therefore, in a series of encoding and decoding processes, it is necessary to adaptively adjust the quantization parameter in response to the transform coefficient as well as the slice type, which can be processed by the transform coefficient-based quantization parameter derivation unit 1327 to be described later.

Meanwhile, FIG. 25 shows a QP range table for determining the quantization step size and QP range for each slice type.

As illustrated in FIG. 25, the slice type based quantization parameter derivation unit 1323 may selectively adaptively adjust the QP Range corresponding to the slice type based on the QP range table.

For this, the selective adaptive QP adjustment information may be indicated in header information as a separate flag, or may be transmitted from the encoding device 100 to the decoding device 200 through separate signaling information.

For example, the QP adjustment flag or signaling information may be 0 (False), and in this case, the quantization unit 130 processes a quantization process according to a fixed QP range, based on a fixed base QP It is possible to determine the applied QP for the picture and slice.

In addition, when the QP adjustment flag or signaling information is 1 (True), the slice type-based quantization parameter derivation unit 1323 determines a selective adaptive QP range based on a table and determines a corresponding base QP. By determining, the QP range corresponding to each slice and picture may be selectively adaptively determined for each CTU quantization block.

More specifically, the slice type-based quantization parameter derivation unit 1323 may determine the minimum QP and the maximum QP corresponding to the slice or picture type in order to selectively adaptively calculate the QP value. Then, the slice type-based quantization parameter derivation unit 1323 calculates detailed QP values for each CTU quantization group unit based on the obtained CTU quantization group unit offset value and the minimum base QP value determined for each slice. You can.

Meanwhile, the slice type-based quantization parameter derivation unit 1323 may perform a hierarchical QP range adjustment of a temporal layer of a picture to which the slice belongs.

Referring to FIG. 25, a slice according to an embodiment of the present invention may be classified into hierarchical slices (B Slice0 to B Slice4) corresponding to a temporal layer of each picture. In addition, the slice type-based quantization parameter derivation unit 1323 may adjust each detailed QP Range according to the classified layer information corresponding to each temporal layer, and may determine the BASE QP and QP values accordingly.

In addition, the slice type-based quantization parameter derivation unit 1323 may adaptively and efficiently determine a quantization parameter value according to characteristic information of an image corresponding to the slice type.

Here, as the characteristic information, resolution information of an image may be illustrated. That is, the slice type-based quantization parameter derivation unit 1323 may adaptively determine at least one of the range, step size, and QP value of the quantization parameter according to the slice type and image resolution. From the perspective of cognitive quality, as a region that can be recognized by a person varies according to the resolution (HD / FHD / 2K / 4K / 8K, etc.) of the image, the slice type-based quantization parameter derivation unit 1323 determines the specific image resolution. This is to allow the QP value to be adjusted by using as a reference point.

The slice type-based quantization parameter derivation unit 1323 may define a QP Resolution operation so that it can be applied according to a resolution, which may include an operation in which QP parameters corresponding to an arbitrary resolution are calculated. The slice type-based quantization parameter derivation unit 1323 may selectively adaptively determine the QP of the slice to be encoded or decoded according to the resolution-based QP parameter calculated by the QP resolution operation.

As another embodiment of the present invention, the slice type based quantization parameter derivation unit 1323 may derive an individual QP value corresponding to an HDR image or a 360 VR image among image characteristics corresponding to the slice type. have.

The slice type-based quantization parameter derivation unit 1323, when the block to be determined QP is a block of an HDR image, the slice type-based quantization parameter derivation unit 1323 corresponds to a block of an image region in which the luminance range is significantly changed, and a relatively high QP Can be applied. For example, the slice type-based quantization parameter derivation unit 1323 obtains a separately designated QP offset value for the illumination adaptive deblocking filter for the QP determination target block from header information, and the QP determination target block is applied by HDR or the like. When the luminance range level is greater than a predetermined value, illuminance adaptive deblocking filtering based on the separately designated QP offset value may be performed. Accordingly, adaptive deblocking filtering for a block of an image region having a large change in the luminance range is selectively adaptively performed, thereby improving subjective image quality.

In addition, the slice type-based quantization parameter derivation unit 1323 identifies a region and a region of interest (ROI) of the image when the QP determination target block is a block of a VR 360 image for virtual reality, and the region of interest is identified in the identified region of interest. It is also possible to set a relatively high QP for the corresponding block.

Meanwhile, the color sample-based quantization parameter deriving unit 1325 may derive a selective adaptive QP value according to the color sample.

More specifically, the color sample-based quantization parameter derivation unit 1325 may calculate the QP value of a chroma color component sample using the QP value of the luminance color component sample.

In addition, the color sample-based quantization parameter derivation unit 1325 may conditionally determine the QP value of the saturation color sample based on the QP value of the illuminance color sample. As the determination condition, i) when a separate block structure is formed between the illuminance sample and the color difference sample matching it, ii) a separate block tree is constructed between the illuminance sample and the color difference sample matching it, and has different block partitioning trees. In the case, iii) various conditions such as the case where the block division characteristics (division direction, division depth, block size, etc.) of the illuminance color sample have a predetermined value may be exemplified. Accordingly, the color sample-based quantization parameter derivation unit 1325 is configured when i) a separate block structure between an illuminance sample and a color difference sample matching it, ii) a separate block tree between an illuminance sample and a color difference sample matching it. Therefore, in case of having different block partitioning trees, iii) for each color condition of the saturation color sample, such as the case where the block partitioning characteristics (division direction, division depth, block size, etc.) of the illuminance color sample have a predetermined value. Whether to derive QP values and quantization offset parameters for deriving QP values may be selectively adaptively determined.

In addition, the color sample-based quantization parameter derivation unit 1325 determines the QP value derivation function of the saturation color sample differently according to the block division characteristics (division direction, division depth, block size, block tree structure, etc.) of the illuminance color sample. , A selective adaptive QP decision can be processed. For example, the adaptive QP decision process according to an embodiment of the present invention can be illustrated as follows.

First, Chroma_QP = Luma_QP-Diff_Offset; Diff_Offset = min (MaxDiff_ChromaQP, LumaQP-Chroma_QP); To deal with.

Referring to the above process, the QP parameter applied to the Chroma Sample can be determined using an offset (Diff_Offset) value defined separately from Luma QP. Here, the Luma QP is a difference value corresponding to an initial QP calculated in advance from header information and block information, and can be calculated from delta QP obtained from header information or block information. Accordingly, when a separate block structure or block tree between the illuminance sample and a color difference sample matching it is configured in dual, Luma QP may be obtained from header information or block information of a block structure or block tree corresponding to illuminance.

The offset may be derived from QP Offset (MaxDiff_ChromaQP) transmitted from the encoding device 100. In addition, the offset may be a smaller or larger value among the difference values between LumaQP and ChromaQP derived in advance. Here, for example, the QP offset may be transmitted as header information signaled from the encoding apparatus 100 according to each condition or block information corresponding to a coding unit or a transformation unit. In particular, the color sample-based quantization parameter derivation unit 1325 is composed of a separate block structure between the i) illuminance sample and the color difference sample matching it, ii) a separate block tree between the illuminance sample and the color difference sample matching it, In a DUAL Tree case or the like having a different block partitioning tree, a QP offset value as a Chroma QP parameter for each unit for individually deriving QPs corresponding to quantization units of a color difference sample tree from LumaQPs from signaling information or decoding target block information Accordingly, the color sample-based quantization parameter derivation unit 1325 may derive the QP of the color difference sample from the Luma QP using the determined Chroma QP parameter.

Also, whether the color sample-based quantization parameter deriving unit 1325 operates and detailed parameters according to an embodiment of the present invention may be derived through separately transmitted flags or signaling information. For example, QP offset information for Chroma QP parameter calculation may be derived from high-level syntax of header information such as PPS or SPS, or may be obtained from block information such as a coding unit and a transformation unit. Also, the Chroma QP parameter calculation The QP offset information for can be configured in a list form corresponding to a quantization unit, and QP values for each color difference sample corresponding to each coding unit or transformation unit are pre-computed Luma QP values and QPs obtained from the list It can be calculated and determined based on the offset information. Here, the list may be derived from high level syntax of header information such as PPS or SPS as described above, or may be obtained from block information such as a coding unit and a transformation unit.

Meanwhile, the transform coefficient-based quantization parameter derivation unit 1327 may process an adaptive quantization parameter determination process in consideration of transform coefficients and encoding characteristics in response to a CTU quantization unit block.

According to an embodiment of the present invention, the transform coefficient may be leveled, and the quantization unit 130 may include a plurality of quantizers for each level (not shown). Such a plurality of quantizers may be mapped to each level, and accordingly, quantization processing for each transform level may be performed in each quantizer. Pre-defined step sizes and coefficient levels for each quantizer may be mapped, and accordingly, a scalar-based scaled quantization process may be processed for each transform coefficient level.

In particular, in the case of performing quantization processing of transform coefficients using the level-based multiple quantizer, the transform coefficient-based quantization parameter deriving unit 1327 corresponds to at least one of the level of each transform coefficient, encoding characteristic information, and image characteristic information. Selective adaptive quantization parameter derivation can be handled.

For example, the encoding characteristic information may include spatial layer information of a picture, slice type information, encoding layer information including an enhancement layer or a base layer, and the like.

In addition, as the characteristic information of the input image, HDR image information, 360 VR image information, image information requesting high image quality of a partial region, or image resolution information may be exemplified.

For example, two or three quantizers (QUANTIZER) that provide level-based quantization processing of transform coefficients may be exemplified.

In the case of a two-quantizer, the first quantizer (BaseQ) that processes the base quantization parameter and a second quantizer (EnhancementQ) that processes the enhanced quantization parameter, and in the case of a three-quantizer, the base It may be composed of a first quantizer corresponding to (BASEQ), a second quantizer corresponding to uplink (HIGHQ) and a third quantizer corresponding to downlink (LOWQ).

When the processing of the quantization unit 130 composed of a plurality of quantizers is performed, the transform coefficient-based quantization parameter derivation unit 1327 may select information of each quantizer, quantization step size, and size according to characteristics of encoding information and image information. The QP range can be determined.

For example, in the case of an HDR image, the transform coefficient-based quantization parameter derivation unit 1327 may determine separate quantization step sizes and ranges using only an uplink quantizer (HighQ) and a base quantizer (baseQ), and correspond to the same. Can induce QP.

In addition, the transform coefficient-based quantization parameter derivation unit 1327 selects a base quantizer (BaseQ) or a down-quantizer (LowQ) corresponding to the resolution information in the case of a general image, and processes the QP value corresponding thereto to be derived. You can.

As described above, since a quantizer may be selected according to encoding information and characteristic information of an image, quantization processing using each quantizer includes a group-by-group difference quantization parameter derivation unit 1330 and a coding block unit adaptive quantization parameter application unit ( 1340).

Particularly, for level classification corresponding to a plurality of quantizers, the quantization unit 130 may perform level classification processing based on a transform coefficient value for a transform block.

The transform coefficient-based quantization parameter derivation unit 1327 may determine at least one of a plurality of quantizers to process quantization based on the processed level classification, image characteristic information, and encoding characteristic information. For example, the encoding characteristic information may include at least one of block structure information, block division information, division depth information, division direction information, or color difference component information. Further, at least one of the plurality of quantizers may be at least one of the above-described two or three quantizers.

Then, the transform coefficient-based quantization parameter derivation unit 1327 may process QP values to be selectively adaptively determined by applying different quantization step sizes according to configuration and selection information of each quantizer.

26 is a view showing in more detail the operation of the quantization unit 130 thus processed.

Referring to FIG. 26, first, the quantization unit 130 derives an initial quantization parameter and an initial quantization parameter list through the initial quantization parameter derivation unit 1310 (S2001).

Then, the quantization unit 130 determines a characteristic adaptive quantization parameter through the characteristic adaptive quantization parameter determination unit 1320 (S2003).

Here, the characteristic adaptive quantization parameter determining unit 1320 includes the above-described image case-based quantization parameter derivation unit 1321, slice type-based quantization parameter derivation unit 1323, color sample-based quantization parameter derivation unit 1325, and transform coefficient-based quantization. A quantization parameter corresponding to the initial quantization parameter list may be selectively adaptively determined for each CTU quantization unit block by using at least one of the parameter derivation units 1327.

Then, the quantization unit 130, through the group unit difference quantization parameter derivation unit 1330, performs quantization processing, and then corresponds to the quantization parameters configured and updated by the list, and sets the difference quantization parameters for each CTU quantization unit block. Derivation (S2005), and adaptive quantization parameters in units of coding blocks are applied accordingly (S2007), so that selective adaptive quantization for each block is processed (S2009).

Although the quantization process described in this way is exemplified to be processed by the encoding device 100, the decoding device 200 can also process in the reverse order. That is, the inverse quantization unit 220 may selectively adaptively determine an inverse quantization parameter for inverse quantization processing of the target block, based on the quantization group unit information of the target block, and subsequent processing is described above. The same or similar treatment as the bar.

Meanwhile, FIGS. 27 to 29 are diagrams illustrating high-level syntax information signaled for the operation of the quantization unit 130 according to an embodiment of the present invention.

FIG. 27 illustrates PPS syntax. Referring to FIG. 27, DIFF_CU_QP_DELTA_DEPTH information and QP offset information for each color difference are signaled as differential information for adaptively determining QP for each CTU quantization unit block through PPS. Can be illustrated.

FIG. 28 illustrates a range extension syntax of PPS. Referring to FIG. 28, Adaptive_Group_QP_list_flag indicating whether adaptive quantization group unit list processing is applied through the range extension syntax of PPS may be signaled, and each corresponding thereto It may be exemplified that offset and index information of the list and offset depth information (DIFF_CU_CHROMA_QP_OFFSET_DEPTH) corresponding to the differential color difference QP are signaled.

Meanwhile, FIG. 29 illustrates slice header syntax according to an embodiment of the present invention. In the slice header, color difference QP offset information and GROUP_QP_LIST [i] for processing each adaptive quantization group unit list are defined, and the slice QP value It may be indicated that this can be applied adaptively. However, such syntax information is exemplified for an embodiment of the present invention, and it is obvious that the expressions or terms may be modified.

Meanwhile, FIGS. 30 to 33 are diagrams for explaining a case in which a QP parameter is adaptively determined when a picture according to an embodiment of the present invention is divided into a plurality of input image segmentation units.

As illustrated in FIGS. 30 and 31, the image division unit according to an embodiment of the present invention may not only be determined corresponding to each coding unit, but also a sub-picture (Sub) that divides one picture separately from the detailed coding unit (Sub picture) unit. As described above, the sub-picture may correspond to a region corresponding to a specific viewpoint in a VR image, etc., and one picture may be composed of a plurality of sub-pictures.

Also, separate signaling information corresponding to the sub-pictures may be transmitted from the encoding device 100 to the decoding device 200. 30 is an exemplary syntax diagram of subpicture signaling information inserted into header information as such signaling information.

30 and 31, sub-picture signaling information according to an embodiment of the present invention includes the total number of sub-pictures (Total_subpics_nums), sub-picture width information (SubPic_Width), and sub-picture height information (SubPic_Height), It may include at least one of sub-picture horizontal split information (Subpic_Hor_split_flag) and sub-picture identification information (Subpic_ID), and further, whether to use information as a picture flag of the sub-picture and whether to allow loop filtering between sub-pictures may be further included. .

For example, as illustrated in FIG. 31, the entire picture may be divided into a plurality of sub-pictures, and sub-picture indices (SubPic [0] [0] to SubPic [2] [2) corresponding to each sub-picture. ]).

Also, subpicture IDs (0 to N) may be assigned to each subpicture. Accordingly, the signaling information may include picture width and height information corresponding to each sub-picture identifier and sub-picture index.

In addition, the sub picture identifier may be included in header information such as SPS or PPS or an SEI message. The sub picture ID may include initial sub picture ID information of the first coded picture in the sequence.

For example, the decoding apparatus 200 may identify a specific picture and identify and update IDs of subpictures in the specific picture based on the subpicture ID information received through the SEI message. Accordingly, the subpicture ID in the sequence can be stored and updated. In addition, the SEI message may be replaced with encoded header information such as PPS or slice header. Accordingly, the decoding apparatus 200 may update the identifier information of the subpicture in the picture using the PPS or slice header.

In addition, the sub-picture identifier may be variably changed. In this case, separate sub-picture Grid information, Index information, or Offset information for indicating the variable may be signaled as sub-picture identifier variable information. The decoding apparatus 200 may determine the location and size of the sub-pictures in the picture based on the signaled sub-picture identifier variable information. IDs of sub-pictures corresponding to sub-pictures having the same size may be flexibly allocated and updated according to the progress of a picture sequence.

In addition, when a sub-picture is divided, a sub-picture split flag indicating this may be designated and included in signaling information. In addition, in the case of the divided right boundary subpicture, width information and height information of the subpicture are respectively designated and may be included in signaling information.

The sub-picture signaling information may be transmitted by being included in header information of a video bitstream such as Sequence Parameter Set (SPS) and Picture Parameter Set (PPS).

More specifically, for example, Total_subpics_nums may be sub-picture signaling information transmitted on the SPS, and may indicate the total number of sub-pictures (or sub-pictures) divided within each picture.

In addition, for example, Subpic_ID may indicate a unique ID assigned to each subpicture.

For example, unique identification information (id) may be allocated and signaled to the sub-picture, and basically, a sub-picture ID may be allocated in Z-Scan order from the top-left to the right bottom of the picture.

In order to allocate a sub-picture ID, sub-picture identification information (Subpic_ID) may be transmitted in the form of a list or a table. The decoding apparatus 200 may set an index based on the total number of sub-pictures, and sequentially allocate IDs of sub-pictures to the index according to a predefined order.

The sub-picture ID may indicate attributes of a sub-picture, and may be used as identification information (ID) for selecting a parameter set to be applied in response to a sub-picture, unlike index information corresponding to each position.

Further, when the sub-picture includes one or more independent slices, the sub-picture ID allocated to the sub-picture may be mapped or corresponded to the slice ID of the slice header. The index or grid information corresponding to the sub picture ID may indicate the structure and size information of each sub picture, or may be used as fixed location information for slice decoding.

Accordingly, the decoding apparatus 200 may selectively adaptively derive and determine various encoding information (reference picture list information, selective adaptive QP allocation, NAL UNIT TYPE, and SLICE TYPE) using ID information of the subpicture.

For example, the decoding apparatus 200 determines the QP offset corresponding to the sub-picture ID, changes the Scanning Order, or refers to a separate optional adaptive parameter set to initialize parameters for each sub-picture. Subpicture id information may be used to determine the QP value.

Accordingly, as illustrated in FIG. 32, a separate parameter set corresponding to the sub picture ID may be referenced. The parameter set may be a picture parameter set or a separately selected adaptive parameter set, and the sub picture id may be configured to be included in the sequence parameter set and mapped to each other parameter set.

For example, the decoding apparatus 200 may decode the size and structure information of each subpicture using Total_subpics_nums and Subpic_Width and Subpic_Height from the subpicture signaling information.

In addition, for example, the decoding apparatus 200 may determine the structure and size information of the subpicture by using the width and height information of the pre-decoded picture and the subpic_width and subpic_height obtained previously. .

Here, the decoding apparatus 200 may determine size information of a subpicture located in a right boundary of a picture through a separate operation.

In addition, the decoding apparatus 200 divides the entire picture width (Picture width) by the sub-picture width (Subpic width) or performs a difference operation, but when the remaining value within a certain size occurs, the sub located at the right boundary of the picture The width of the picture (Subpicture_Width) may be derived from the remaining values.

For example, if Picture width: 1920, Subpic width 896 (128 CTU X 7), the width of SubPic [2] [0] can be derived to 128. (1920 X (896 * 2))

Meanwhile, Subpic_Hor_split_flag may be signaled when the height or width of the current sub-picture is smaller than the sub-picture of the upper left (Left-Top), and may include segmentation information including a segmentation ratio, segmentation direction, or segmentation size.

For example, in the decoding apparatus 200, sub-pictures obtained by subpic_Hor_split_flag are sub-pictures whose height is horizontally divided according to a height corresponding to a sub-picture of a left-top. With the current sub-pictures can be configured. Accordingly, the divided subpicture list may be included in the signaling information and transmitted, for example, the entire substructure information of the subpicture may be derived according to index and offset information for each subpicture.

Therefore, even if the sub picture is primarily configured as a 3x2 division unit from the signaled information, the decoding apparatus 200 uses the remaining information (total number of sub pictures, split flag information, etc.) to more accurate sub picture for each index. You can derive the size and position of the.

Meanwhile, FIG. 33 is a diagram for explaining a process of changing a subpicture id that is variable according to an embodiment of the present invention. As described above, a unique ID may be assigned to each sub-picture, and for example, a sub-picture ID within a specific sequence unit may be variable.

That is, the Subpic_ID corresponding to the subpicture may be variably determined based on separate signaling information. The sub picture identification information may be mapped to a parameter set to be referenced in order to determine a QP value for the sub picture. According to the variation of the sub picture identification information, a parameter set to be referred to for determining the QP value for each sub picture may also be changed. For example, when the main view to be viewed by the user changes in the VR image, for example, the decoding apparatus 200 changes the current sub-picture identification information to sub-picture identification information for the main view, thereby referring to a parameter for reference to determine the QP value You can change the set.

The method according to the present invention described above is produced as a program to be executed on a computer and can be stored in a computer-readable recording medium. Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, and magnetic tape. , Floppy disks, optical data storage devices, and the like, and also implemented in the form of a carrier wave (for example, transmission via the Internet).

The computer-readable recording medium can be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for implementing the method can be easily inferred by programmers in the technical field to which the present invention pertains.

In addition, although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the present invention belongs without departing from the gist of the present invention claimed in the claims. In addition, various modifications can be implemented by a person having ordinary knowledge in the course, and these modifications should not be individually understood from the technical idea or prospect of the present invention.

Claims

In the image processing method,

The picture of the image is divided into a plurality of coding units, which are a basic unit in which inter prediction or intra prediction is performed, and the picture or the divided coding unit is a quad tree. ), Determining a target block for decoding a coding unit divided into a binary tree or a ternery tree structure; And

And selectively adaptively determining a quantization parameter for quantization processing of the target block based on the coding tree unit-based quantization group unit information including the target block.

Image processing method.
The method of claim 1,

The determining step,

And adaptively determining the quantization group unit based on the coding tree unit according to the characteristics of the target block.

Image processing method.
According to claim 2,

The determining step,

And constructing an initial quantization parameter list corresponding to the quantization group units based on the coding tree unit, according to delta QP index information corresponding to the quantization group units.

Image processing method.
The method of claim 1,

The determining step,

And selectively adaptively determining at least one of a quantization size, a quantization range, and a quantization parameter according to the characteristic information of the image.

Image processing method.
According to claim 4,

The step of selectively adaptively determining the at least one,

And selectively adaptively determining the quantization parameter in response to image case information obtained from the image.

Image processing method.
According to claim 4,

The step of selectively adaptively determining the at least one,

And selectively adaptively determining the quantization parameter in response to slice type information obtained from the image.

Image processing method.
According to claim 4,

The step of selectively adaptively determining the at least one,

And selectively adaptively determining the quantization parameter in response to color sample information obtained from the image.

Image processing method.
The method of claim 7,

The color sample information includes a chrominance quantization offset parameter signaled separately to derive a quantization parameter of a chroma sample of the target block from a quantization parameter of a luma sample.

Image processing method.
According to claim 4,

The step of selectively adaptively determining the at least one,

And selectively adaptively determining the quantization parameter in response to level information of a transform coefficient obtained from the image.

Image processing method.
The method of claim 1,

And using the determined quantization parameter, deriving a differential quantization parameter for each quantization group unit,

The quantization group unit corresponds to at least one of a slice, tile, brick, or subpicture unit that is a division unit of the picture.

Image processing method.
The method of claim 9,

And calculating a quantization parameter of a coding block unit in the quantization group unit using the derived differential quantization parameter and initial quantization parameter.

Image processing method.
The method of claim 10,

And performing selective adaptive quantization for each coding block unit according to the quantization parameter.

Image processing method.
In the video encoding apparatus,

The picture of the image is divided into a plurality of coding units, which are a basic unit in which inter prediction or intra prediction is performed, and the picture or the divided coding unit is a quad tree. ), A block dividing unit for determining a target block for decoding a coding unit divided into a binary tree or a ternery tree structure; And

And a quantization unit selectively adaptively determining a quantization parameter for quantization processing of the target block, based on the coding tree unit-based quantization group unit information including the target block.

Video encoding device.
In the video decoding apparatus,

The picture of the image is divided into a plurality of coding units, which are a basic unit in which inter prediction or intra prediction is performed, and the picture or the divided coding unit is a quad tree. ), A block dividing unit for determining a target block for decoding a coding unit divided into a binary tree or a ternery tree structure; And

And an inverse quantization unit selectively adaptively determining an inverse quantization parameter for inverse quantization processing of the target block based on coding tree unit-based quantization group unit information including the target block.

Video decoding device.