WO2017119540A1

WO2017119540A1 - Method and device for predicting residual signal

Info

Publication number: WO2017119540A1
Application number: PCT/KR2016/001094
Authority: WO
Inventors: 전동산; 강정원; 고현석; 이진호; 임성창; 김휘용; 최진수
Original assignee: 한국전자통신연구원
Priority date: 2016-01-05
Filing date: 2016-02-01
Publication date: 2017-07-13
Also published as: CN113891093A; KR20170082071A; CN108432247B; KR20230112594A; CN113891094A; KR20220002207A; CN113891095A; CN108432247A; KR102448084B1; KR102558803B1; KR102345475B1; KR20220136308A; CN113891092A; CN113891091A

Abstract

A method and a device for predicting a residual signal are disclosed. An encoding method and an encoding device additionally predict a residual signal of a current block by using a residual signal of a neighboring block, thereby generating a predicted residual signal. A decoding method and a decoding device use a residual signal of a neighboring block, which has already been reconstructed, in the generation of a reconstructed block of the current block. In encoding and decoding, a value of a prediction sample used for generating a prediction block can be updated prior to the generation of the prediction block. An encoding efficiency can be improved through the prediction of the residual signal and update of the prediction sample.

Description

Method and apparatus for prediction of residual signal

The following embodiments relate to a video decoding method, a decoding device, an encoding method, and an encoding device, and more particularly, to a method and an apparatus for predicting a residual signal.

Through the continuous development of the information and telecommunications industry, broadcasting services having high definition (HD) resolution have spread worldwide. This proliferation has resulted in many users becoming accustomed to high resolution and high quality images.

In order to satisfy the demand of users for high image quality, many organizations are spurring the development of next generation video equipment. For users of Ultra High Definition (UHD) TVs that have four times the resolution of FHD TVs, as well as High Definition TV (HDTV) and Full HD (FHD) TVs. Interest has increased, and as the interest increases, image encoding / decoding techniques for images having higher resolution and image quality are required.

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

In encoding and decoding of an image, prediction may mean generating a prediction signal similar to the original signal. Predictions can be broadly classified into predictions referring to spatial reconstructed images, predictions referring to temporal reconstructed images, and predictions on other symbols.

Intra prediction may be a prediction technique that allows only spatial reference. The current block may be a block targeted for current encoding. Intra prediction may be a method of predicting the current block by referring to reference samples already reconstructed around the current block.

In intra prediction, the surrounding reference sample may be a predicted and reconstructed brightness value, not a brightness value in the original image, and may be a value before post-processing filtering is applied. Since the reference sample has been previously encoded and reconstructed, it can be used for prediction of the current block in an encoder and a decoder.

However, conceptually, intra prediction may be effective only in a flat region with continuity and a constant directionality with respect to surrounding reference signals. For regions without such intra-image characteristics, the efficiency of the encoding efficiency of intra prediction may be significantly lower than the encoding efficiency of inter prediction. In particular, when encoding an image, the first picture may be encoded only by intra prediction, and the picture may be encoded only by intra prediction for random access and error robustness. Therefore, there is a need for a method capable of improving the efficiency of encoding of intra prediction.

One embodiment may provide a method and apparatus for updating a reference sample used for intra prediction to be as close as possible to the current block to be encoded, in order to improve the efficiency of intra coding.

An embodiment can provide a method and apparatus for predicting a residual signal of a current block by using a residual signal of a neighboring block that has already been encoded or decoded.

The image encoding method of claim 1, further comprising: generating a first residual signal of the current block based on the residual signal of a first neighboring block of the current block; And encoding the current block by using the first residual signal of the current block.

The encoding method of the image may further include generating a second residual signal of the current block.

The second residual signal may be a difference between the current block and a prediction block of the current block.

The first residual signal may be generated based on the second residual signal and the residual signal of the neighboring block.

The first residual signal may be generated based on a difference between the second residual signal and the residual signal of the first neighboring block.

The first residual signal may be a difference between the second residual signal and the residual signal of the first neighboring block.

The encoding method of the image may further include determining whether to perform a residual signal prediction.

The generating may be performed when it is determined that the residual signal prediction is performed.

The encoding method of the image may further include encoding information indicating whether the residual signal prediction is performed.

The encoding method may further include encoding an identifier of the first neighboring block.

In another aspect, a method of decoding an image, the method comprising: generating a prediction block of a current block; And generating a reconstructed block of the current block based on the prediction block, the residual signal of the current block, and the residual signal of the first neighboring block of the current block.

The reconstruction block may be generated based on the sum of the residual signal of the current block and the residual signal of the first neighboring block.

The reconstruction block may be a sum of a prediction block of the current block, a residual signal of the current block, and a residual signal of the first neighboring block.

The decoding method of the image may further include generating a residual signal of the current block.

The decoding method of the image may further include identifying the first neighboring block.

The first neighboring block may be identified by an identifier of the first neighboring block.

If the identifier of the first neighboring block does not exist, the selected block may be identified as the first neighboring block in a predefined manner.

The decoding method of the image may further include updating a value of a reference sample used to generate the prediction block.

In still another aspect, a method of decoding an image, the method comprising: determining a value of a reference sample based on a neighboring block of a current block; And generating a prediction block of the current block by using the reference sample.

The value of the reference sample may be determined based on the inclination pattern of the peripheral block.

When the inclination pattern is symmetrical, the value of the reference sample may be determined based on the inclination value of two lines forming the symmetry of the inclination pattern.

The value of the reference sample may be determined based on a slope value between two adjacent reference samples among a plurality of reference samples belonging to one row of the neighboring block.

In the determining, the value of the reference sample may be changed from a value before the update to a value after the update.

The value before the update may be a value generated as the block including the reference sample is predicted and reconstructed.

When the intra prediction mode for the current block is a horizontal prediction mode, the reference sample is a sample adjacent to the left side of the current block, and the neighboring block is a top neighboring block of the current block and a top left neighboring block of the current block. It may be a combined block.

According to another aspect, an image encoding method includes: determining a value of a reference sample based on a neighboring block of a current block; And generating a prediction block of the current block by using the reference sample.

In order to improve the efficiency of intra coding, a method and apparatus are provided for updating a reference sample used for intra prediction to be as close as possible to the current block that is the object of encoding.

Provided are a method and an apparatus for predicting a residual signal of a current block by using a residual signal of a neighboring block that has already been encoded or decoded.

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

2 is a block diagram illustrating a configuration of a decoding apparatus according to an embodiment of the present invention.

3 is a diagram schematically illustrating a division structure of an image when encoding and decoding an image.

4 to 11 illustrate the types of prediction units PUs that a coding unit CU may include.

FIG. 12 illustrates a form of a transform unit (TU) that may be included in a coding unit (CU).

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

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

15 is a structural diagram of an encoding apparatus according to an embodiment.

16 and 17 are flowcharts of an encoding method, according to an embodiment.

18 is a flowchart of an encoding method according to an embodiment.

19 is a flowchart of a method of updating a reference sample, according to an embodiment.

20 is a flowchart of a method of predicting a residual signal, according to an exemplary embodiment.

21 is a flowchart of a method of encoding a current block, according to an embodiment.

22 illustrates a current block and a reference sample according to an example.

23 illustrates a method of updating a reference sample by reflecting an inclination in a horizontal direction of a neighboring block according to an example.

24 illustrates a method of obtaining an inclination pattern according to an example.

25 is a view illustrating a method of updating a reference sample by reflecting an inclination of a peripheral block in a vertical direction according to an example.

26 illustrates intra prediction with 33 respective modes according to an example.

27 shows intra prediction with 65 respective modes according to an example.

28 is a view illustrating an area of an image according to an example.

29 illustrates a method of calculating a residual signal of a neighboring block according to an example.

30 illustrates a method of calculating a residual signal of a current block according to an example.

31 illustrates a residual signal prediction method according to an example.

32 illustrates a default residual signal according to an example.

33 illustrates a result of discrete cosine transform on a default residual signal according to an example.

34 illustrates a proposed residual signal according to an example.

35 shows a result of discrete cosine transform for a proposed residual signal according to an example.

36 illustrates a position of a neighboring block according to an example.

37 is a structural diagram of a decoding apparatus according to an embodiment.

38 and 39 are flowcharts of a decoding method, according to an exemplary embodiment.

40 is a flowchart of a method of generating a residual signal, according to an exemplary embodiment.

41 is a flowchart of a method of decoding a current block using a residual signal according to an embodiment.

42 is a flowchart of a prediction block generation method, according to an embodiment.

43 is a flowchart of a method of generating a restored block according to an embodiment.

44 is a structural diagram of an electronic device implementing an encoding device according to an embodiment.

45 is a structural diagram of an electronic device implementing a decoding apparatus according to an embodiment.

DETAILED DESCRIPTION For the following detailed description of exemplary embodiments, reference is made to the accompanying drawings that show, by way of illustration, specific embodiments. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments. It should be understood that the various embodiments are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention with respect to one embodiment. In addition, it is to be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the embodiments. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the exemplary embodiments, if properly described, is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects. Shape and size of the elements in the drawings may be exaggerated for clarity.

When a component is said to be "connected" or "connected" to another component, the above two components may be directly connected to or connected to each other, It is to be understood that other components may exist in the middle of the two components. In addition, the description "including" a specific configuration in the exemplary embodiments does not exclude a configuration other than the specific configuration described above, the additional configuration is the implementation of the exemplary embodiments or the technical spirit of the exemplary embodiments. It can be included in the range.

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

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

In addition, some of the components may not be essential components for performing essential functions, but may be optional components for improving performance. Embodiments may be implemented including only components necessary to implement the nature of the embodiments, and structures including the optional components, such as, for example, components used only for performance improvement, are also included in the scope of rights.

Hereinafter, in order to enable those skilled in the art to easily implement the embodiments, embodiments will be described in detail with reference to the accompanying drawings. In describing the embodiments, when it is determined that the detailed description of the related well-known configuration or function may obscure the subject matter of the present specification, the detailed description thereof will be omitted.

Hereinafter, the image may mean one picture constituting a video and may represent the video itself. For example, "encoding and / or decoding of an image" may mean "encoding and / or decoding of a video" and may mean "encoding and / or decoding of one of images constituting the video." It may be.

First, terms used in the embodiments will be described.

Unit: In encoding and decoding of an image, a unit may be an area generated by division of one image. One image may be divided into a plurality of units. In encoding and decoding of an image, a predetermined process may be performed for each unit. Depending on the function, units such as blocks, macro blocks, coding units (CUs), prediction units (PUs), and transform units (TUs) are used. One unit may be further divided into subunits having a smaller size than the unit.

The block partitioning information may include information about the depth of the unit. The depth information may indicate the number and / or degree of division of the unit.

One unit may be divided into a plurality of sub-units hierarchically with depth information based on a tree structure. In other words, the unit and the lower unit generated by the division of the unit may correspond to the node and the child node of the node, respectively. Each divided subunit may have depth information. Since the depth information of the unit indicates the number and / or degree of division of the unit, the division information of the lower unit may include information about the size of the lower unit.

In the tree structure, the highest node may correspond to the first unit that is not split. The highest node may be referred to as a root node. In addition, the highest node may have a minimum depth value. At this time, the highest node may have a depth of level 0.

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

A leaf node having a depth of level 3 may represent a unit generated as the first unit is divided three times. The leaf node may be the lowest node and may have the maximum depth value.

Block: The block may be an MxN array of samples. M and N may each be a positive integer. A block can often mean an array of two-dimensional samples. The sample may be a pixel or pixel value.

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

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

Rate-distortion optimization: The encoding apparatus uses a combination of the size of the coding unit, the prediction mode, the size of the prediction unit, the motion information, and the size of the transform unit to provide high coding efficiency. Distortion optimization can be used.

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

[Equation 1]

D + λ * R

D may represent distortion. D may be the mean square error of the squares of difference values between the original transform coefficients and the reconstructed transform coefficients in the transform block.

R can represent the rate. R may indicate a bit rate using the associated context information.

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

The encoding apparatus performs processes such as inter prediction and / or intra prediction, transformation, quantization, entropy encoding, inverse quantization, and inverse transformation to calculate accurate D and R, which can greatly increase the complexity in the encoding apparatus. have.

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

Referring to FIG. 1, the encoding apparatus 100 may include a motion predictor 111, a motion compensator 112, an intra predictor 120, a switch 115, a subtractor 125, a transformer 130, and quantization. The unit 140 may include an entropy encoder 150, an inverse quantizer 160, an inverse transform unit 170, an adder 175, a filter unit 180, and a reference picture buffer 190.

The encoding apparatus 100 may encode the input image in an intra mode and / or an inter mode. In addition, the encoding apparatus 100 may generate a bitstream through encoding of the input apparatus, and may output the generated bitstream. The switch 115 may be switched to intra when the intra mode is used, and the switch 115 may be switched to inter when the inter mode is used.

The encoding apparatus 100 may generate a prediction block for the input block of the input image. In addition, after the prediction block is generated, the encoding apparatus 100 may encode a residual between the input block and the prediction block. The input image may be referred to as a current image that is a target of current encoding. The input block may be referred to as a current block that is a target of current encoding.

When the prediction mode is the intra mode, the intra prediction unit 120 may use the pixel value of an already encoded block around the current block as a reference pixel. The intra predictor 120 may perform spatial prediction using the reference pixel, and generate prediction samples for the input block through spatial prediction.

When the prediction mode is the inter mode, the motion predictor 111 may search an area that best matches the input block from the reference image in the motion prediction process, and derive a motion vector using the searched area. . The reference picture may be stored in the reference picture buffer 190, and may be stored in the reference picture buffer 190 when encoding and / or decoding of the reference picture is processed.

The motion compensator 112 may generate a prediction block by performing motion compensation using a motion vector. Here, the motion vector may be a two-dimensional vector used for inter prediction. In addition, the motion vector may indicate an offset between the current picture and the reference picture.

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

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

Quantized transform coefficient levels may be generated by applying quantization to the transform coefficients. In the following embodiments, the quantized transform coefficient level may also be referred to as transform coefficient.

The quantization unit 140 may generate a quantized transform coefficient level by quantizing the transform coefficients according to the quantization parameter, and output the quantized transform coefficient level. In this case, the quantization unit 140 may quantize the transform coefficients using the quantization matrix.

The entropy encoder 150 may generate a bitstream by performing entropy encoding according to probability distribution on the values calculated by the quantizer 140 or the encoding parameter values calculated in the encoding process, and the like. You can output

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

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

For example, coding parameters include prediction modes, motion vectors, reference picture indexes, coding block patterns, presence or absence of residual signals, transform coefficients, quantized transform coefficients, quantization parameters, block sizes, block partitions. It may include values or statistics such as information. The prediction mode may indicate an intra prediction mode or an inter prediction mode.

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

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

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

When the encoding apparatus 100 performs encoding through inter prediction, the encoded current image may be used as a reference image with respect to other image (s) to be processed later. Therefore, the encoding apparatus 100 may decode the encoded current image again and store the decoded image as a reference image. Inverse quantization and inverse transform on the encoded current image may be processed for decoding.

The quantized coefficients may be inversely quantized in inverse quantization unit 160. The inverse transform unit 170 may be inversely transformed. The inverse quantized and inverse transformed coefficients may be summed with the prediction block via the adder 175. A reconstructed block may be generated by adding the inverse quantized and inverse transformed coefficients and the prediction block.

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

The deblocking filter may remove block distortion generated at boundaries between blocks. SAO may add an appropriate offset value to the pixel value to compensate for coding errors. The ALF may perform filtering based on a comparison value between the reconstructed image and the original image. The reconstructed block that has passed through the filter unit 180 may be stored in the reference picture buffer 190.

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

Referring to FIG. 2, the decoding apparatus 200 may include an entropy decoder 210, an inverse quantizer 220, an inverse transform unit 230, an intra predictor 240, a motion compensator 250, and an adder 255. The filter unit 260 may include a reference picture buffer 270.

The decoding apparatus 200 may receive a bitstream output from the encoding apparatus 100. The decoding apparatus 200 may decode the bitstream in an intra mode or an inter mode. In addition, the decoding apparatus 200 may generate a reconstructed image through decoding and output the reconstructed image.

When the prediction mode used for decoding is an intra mode, the switch may be switched to intra. When the prediction mode used for decoding is an inter mode, the switch may be switched to inter.

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

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

The quantized coefficient may be inverse quantized by the inverse quantizer 220 and inversely transformed by the inverse transformer 230. As a result of inverse quantization and inverse transformation of the quantized coefficients, a reconstructed residual block may be generated. In this case, the inverse quantization unit 220 may apply a quantization matrix to the quantized coefficients.

When the intra mode is used, the intra predictor 240 may generate a predictive block by performing spatial prediction using pixel values of blocks already encoded around the current block. When the inter mode is used, the motion compensator 250 may generate a predictive block by performing motion compensation using a reference vector stored in the motion vector and the reference picture buffer 270.

The reconstructed residual block and the prediction block may be added through the adder 255. As the reconstructed residual block and the prediction block are added, the generated block may pass through the filter unit 260. The filter unit 260 may apply at least one or more of the deblocking filter, SAO, and ALF to the reconstructed block or the reconstructed picture. The filter unit 260 may output the reconstructed image. The reconstructed picture may be stored in the reference picture buffer 270 and used for inter prediction.

In order to efficiently divide an image, a coding unit (CU) may be used in encoding and decoding. A unit may be a term that collectively refers to a block including 1) a syntax element and 2) image samples. For example, "division of a unit" may mean "division of a block corresponding to a unit".

Referring to FIG. 3, an image 300 is sequentially divided in a largest coding unit (LCU), and a split structure is determined in units of an LCU. Here, the LCU may be used as the same meaning as a coding tree unit (CTU).

The partition structure may mean a distribution of a coding unit (CU) in the LCU 310. The CU may be a unit for efficiently encoding an image. This distribution may be determined according to whether to divide one CU into four CUs. The horizontal size and the vertical size of the CU generated by the split may be half of the horizontal size and half of the vertical size, respectively, before the split. The partitioned CU may be recursively divided into four CUs whose width and length are reduced by half in the same manner.

At this time, partitioning of the CU may be performed recursively up to a predetermined depth. Depth information may be information indicating the size of a CU. Depth information may be stored for each CU. For example, the depth of the LCU may be zero, and the depth of the smallest coding unit (SCU) may be a predefined maximum depth. Here, the LCU may be a coding unit having a maximum coding unit size as described above, and the SCU may be a coding unit having a minimum coding unit size.

The division starts from the LCU 310, and the depth of the CU increases by one each time the division reduces the horizontal and vertical sizes of the CU by half. For each depth, the CU that is not divided may have a size of 2N × 2N. In the case of a partitioned CU, a 2N × 2N sized CU may be divided into four CUs having an N × N size. The magnitude of N decreases in half for every 1 increase in depth.

Referring to FIG. 3, an LCU having a depth of 0 may be 64 × 64 pixels. 0 may be the minimum depth. An SCU of depth 3 may be 8x8 pixels. 3 may be the maximum depth. In this case, a CU of 64x64 pixels, which is an LCU, may be represented by a depth of zero. A CU of 32x32 pixels may be represented by depth one. A CU of 16 × 16 pixels may be represented by depth two. A CU of 8x8 pixels, which is an SCU, may be represented by depth 3.

In addition, information on whether the CU is split may be expressed through split information of the CU. The split information may be 1 bit of information. All CUs except the SCU may include partition information. For example, if the value of the partition information is 0, the CU may not be split. If the value of the partition information is 1, the CU may be split.

A CU that is no longer split among CUs partitioned from the LCU may be divided into one or more prediction units (PUs). This process may also be called division.

The PU may be a basic unit for prediction. The PU may be encoded and decoded in any one of a skip mode, an inter mode, and an intra mode. The PU may be divided into various forms according to modes.

As shown in FIG. 4, in the skip mode, there may be no partition in the CU. In the skip mode, the 2N × 2N mode 410 having the same size as the CU without splitting may be supported.

In the inter mode, eight divided forms in a CU may be supported. For example, in the inter mode, 2Nx2N mode 410, 2NxN mode 415, Nx2N mode 420, NxN mode 425, 2NxnU mode 430, 2NxnD mode 435, nLx2N mode 440, and nRx2N Mode 445 may be supported.

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

A transform unit (TU) may be a basic unit used for a process of transform, quantization, inverse transform, and inverse quantization in a CU. The TU may have a square shape or a rectangular shape.

Of the CUs partitioned from the LCU, a CU that is no longer split into CUs may be split into one or more TUs. In this case, the partition structure of the TU may be a quad-tree structure. For example, as shown in FIG. 12, one CU 510 may be divided one or more times according to the quadtree structure. Through division, one CU 510 may be configured with TUs of various sizes.

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

The number of intra prediction modes may be fixed to 35 regardless of the size of the prediction unit.

The prediction mode may include two non-directional modes and 33 directional modes as shown in FIG. 13. Two non-directional modes may include a DC mode and a Planar mode.

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

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

Intra encoding and / or decoding may be performed using sample values or encoding parameters included in neighboring reconstructed units.

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

The rectangle illustrated in FIG. 14 may represent an image (or a picture). In addition, arrows in FIG. 14 may indicate prediction directions. That is, the image may be encoded and / or decoded according to the prediction direction.

Each picture (or picture) may be classified into an I picture (Intra Picture), a P picture (Uni-prediction Picture), and a B picture (Bi-prediction Picture) according to an encoding type. Each picture may be encoded according to an encoding type of each picture.

When the image to be encoded is an I picture, the image may be encoded with respect to the image itself without inter prediction. When the image to be encoded is a P picture, the image may be encoded through inter prediction using a reference image only in the forward direction. When the image to be encoded is a B picture, the image to be encoded may be encoded through inter prediction using reference pictures in both the forward and reverse directions, and may be encoded through inter prediction using the reference picture in one of the forward and reverse directions.

The pictures of the P picture and the B picture that are encoded and / or decoded using the reference picture may be regarded as a picture using inter prediction.

In the following, inter prediction according to an embodiment is described in detail.

Inter prediction may be performed using reference picture and motion information. In addition, inter prediction may use the skip mode described above.

The reference picture may be at least one of a previous picture of the current picture or a subsequent picture of the current picture. In this case, inter prediction may perform prediction on blocks of the current picture based on the reference picture. Here, the reference picture may mean an image used for prediction of the block.

In this case, an area in the reference picture may be specified by using a reference picture index refIdx indicating a reference picture, a motion vector to be described later, and the like.

The inter prediction may select a reference picture and a reference block corresponding to the current block within the reference picture, and generate the prediction block for the current block using the selected reference block. The current block may be a block targeted for current encoding or decoding among blocks of the current picture.

The motion information may be derived during inter prediction by each of the encoding apparatus 100 and the decoding apparatus 200. In addition, the derived motion information may be used to perform inter prediction.

In this case, the encoding apparatus 100 and the decoding apparatus 200 use the motion information of the recovered neighboring block and / or the motion information of the collocated block (col block) to improve encoding and / or decoding efficiency. Can be improved. The call block may be a block corresponding to the current block in a collocated picture (col picture). The reconstructed neighboring block may be a block within the current picture and may be a block that is already reconstructed through encoding and / or decoding. Also, the reconstruction block may be a neighboring block adjacent to the current block and / or a block located at an outer corner of the current block. Here, the block located at the outer corner of the current block may be a block vertically adjacent to a neighboring block horizontally adjacent to the current block or a block horizontally adjacent to a neighboring block vertically adjacent to the current block.

Each of the encoding apparatus 100 and the decoding apparatus 200 may determine a block existing at a position corresponding to a current block spatially in the call picture, and may determine a predetermined relative position based on the determined block. The predefined relative position may be a position inside and / or outside of a block that exists spatially at a position corresponding to the current block. In addition, each of the encoding apparatus 100 and the decoding apparatus 200 may derive a call block based on the determined predetermined relative position. Here, the call picture may be one picture among at least one reference picture included in the reference picture list.

The method of deriving the motion information may vary according to the prediction mode of the current block. For example, as a prediction mode applied for inter prediction, there may be an advanced motion vector predictor (AMVP) and merge.

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

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

The decoding apparatus 200 may select the prediction motion vector of the current block from the prediction motion vector candidates included in the prediction motion vector candidate list by using the prediction motion vector index.

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

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

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

In this case, the merge may be applied in a CU unit or a PU unit. When merging is performed in a CU unit or a PU unit, the encoding apparatus 100 may transmit predefined information to the decoding apparatus 200 through a bitstream. The bitstream may include predefined information. The predefined information may include 1) information indicating whether to merge for each block partition, and 2) information about which one of neighboring blocks adjacent to the current block to merge with. For example, the neighboring blocks of the current block may include a left neighboring block of the current block, a top neighboring block of the current block, a temporal neighboring block of the current block, and the like.

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

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

In the following embodiments, residual signal prediction is described. In general, in existing video encoding and / or decoding techniques such as High Efficiency Video Coding (HEVC) and Advanced Video Coding (AVC), the current block is used to encode and / or decode the current block. The residual signal of is generated. When the residual signal is generated, the residual signal predicted once more may be generated through the residual signal prediction using the residual signal of the neighboring blocks of the current block.

The residual signal prediction may be to predict the residual signal of the current block with respect to the residual signal of the neighboring block. Alternatively, the residual signal prediction may be to use a difference between the residual signal of the current block and the residual signal of the neighboring block as a new residual signal of the current block.

The residual signal obtained through the residual signal prediction may have an advantage in terms of coding efficiency compared to the residual signal obtained by using an existing intra prediction method. For example, the amount of bits generated for the residual signal may be reduced by using the residual signal obtained by using the residual signal prediction.

In the following embodiments, the residual signal obtained by using the residual signal prediction may be referred to as a first residual signal, and the residual signal obtained by using an existing intra prediction method may be referred to as a second residual signal.

In addition, the update of the reference sample is described in the following embodiments. The reference sample is used to generate the predictive block. Therefore, if the reference sample has a feature similar to the expected feature of the current block that is the object of encoding or decoding, the efficiency of encoding or the efficiency of decoding can be improved. In the following, embodiments of updating the reference sample according to a predefined condition before generation of the prediction block are described.

15 is a structural diagram of an encoding apparatus according to an embodiment.

The encoding apparatus 800 may correspond to the above-described encoding apparatus 100. The encoding apparatus 800 includes a motion predictor 111, a motion compensator 112, an intra predictor 120, a switch 115, a subtractor 125, a transformer 130, a quantizer 140, and entropy. The encoder 150, an inverse quantizer 160, an inverse transform unit 170, an adder 175, a filter unit 180, and a reference picture buffer 190 may be included, and the intra residual prediction unit 810 may be included. It may further include.

The motion predictor 111, the motion compensator 112, the intra predictor 120, the switch 115, the subtractor 125, the transformer 130, the quantizer 140, the entropy encoder 150, The inverse quantization unit 160, the inverse transform unit 170, the adder 175, the filter unit 180, and the reference picture buffer 190 may perform functions and / or operations as described above with reference to FIG. 1. . Duplicate explanations are omitted.

In addition, the motion predictor 111, the motion compensator 112, the intra predictor 120, the switch 115, the subtractor 125, the transform unit 130, the quantization unit 140, and the entropy encoding unit 150. ), The inverse quantization unit 160, the inverse transform unit 170, the adder 175, the filter unit 180, and the reference picture buffer 190 may perform functions and / or operations related to the intra residual prediction unit 810. Can be. The motion compensator 112, the intra predictor 120, the switch 115, the subtractor 125, the transformer 130, the quantizer 140, the entropy encoder 150, the inverse quantizer 160, Functions and / or operations of the inverse transform unit 170, the adder 175, the filter unit 180, the reference picture buffer 190, and the intra residual predictor 810 are described in detail below.

The intra residual predictor 810 may not be distinguished from the intra predictor 120. The intra predictor 120 and the intra residual predictor 810 may be integrated into the intra predictor 120. In embodiments, the functions and / or operations described as being performed by the intra residual predictor 810 may be performed by the intra predictor 120.

In addition, the decoding apparatus 2300 corresponding to the encoding apparatus 800 according to an embodiment will be described in detail with reference to FIG. 37 below.

16 and 17 are flowcharts of an encoding method, according to an embodiment.

Hereinafter, the current block may be a block that is the target of the current encoding or may be a block in the current image.

First, referring to FIG. 16, step 910 may be performed.

Prior to performing step 910, a reference sample may be generated. Generation of a reference sample according to an example will be described in detail with reference to FIG. 22 below.

In generating a reference sample, a method of generating a reference sample of an existing image encoding and / or decoding technique such as high efficiency video coding and enhanced video coding may be used.

In operation 910, the intra prediction unit 120 may determine whether to update the reference sample. Here, updating the reference sample may be to refine the sample value of the reference sample used for generation of the prediction block before generating the prediction block of the current block.

If it is determined to perform an update of the reference sample, step 915 may be performed. If it is determined not to perform the reference sample update,

steps

920 and 970 may be performed.

In operation 915, the intra prediction unit 120 may update the value of the reference sample, and may determine the value of the reference sample used to generate the prediction block of the current block through the update.

The intra predictor 120 may update the reference sample value according to the directional pattern of the neighboring sample.

Update of a reference sample according to an example will be described in detail with reference to FIGS. 23, 24 and 25 below.

After step 915 is executed, step 920 and step 970 may be performed.

In operation 920, the intra prediction unit 120 may perform intra prediction. The intra predictor 120 may generate a prediction block of the current block. The intra prediction unit 120 may generate the prediction block of the current block by using the reference sample according to the intra prediction mode for the current block.

For example, in generating a prediction block, a prediction block generation method of an existing image encoding and / or decoding technique such as HEVC and AVC may be used.

After step 920 is performed, step 930 may be performed.

In operation 930, the intra residual prediction unit 810 may determine whether to perform the residual signal prediction.

If it is determined to perform the residual signal prediction, steps 935, 940, and 980 may be performed.

If it is determined not to perform residual signal prediction, steps 960 and 980 may be performed.

In operation 935, the intra residual predictor 810 may determine a first neighboring block among one or more neighboring blocks of the current block. The first neighboring block may be a block used for residual signal prediction. Determination of a neighboring block according to an example will be described in detail with reference to FIG. 20 below.

After step 935 is performed, step 950 and step 985 may be performed.

In operation 940, the intra predictor 120 may generate a second residual signal of the current block using intra prediction. The intra predictor 120 may generate a second residual signal of the current block based on the intra prediction mode and the reference sample for the current block.

The second residual signal may correspond to the residual signal of the current block in existing video encoding and / or decoding techniques such as HEVC and AVC. For example, in the generation of the second residual signal, a residual signal generation method of an existing video encoding and / or decoding technique such as HEVC and AVC may be used.

The generation of the second residual signal according to an example will be described in detail with reference to FIGS. 28, 29, and 30 below.

After step 940 is performed, step 950 may be performed.

When step 935 and step 940 are performed as the residual signal prediction is determined to be performed, step 950 may be performed next.

In operation 950, the intra residual predictor 810 may generate a first residual signal of the current block according to the residual signal prediction.

The intra residual predictor 810 may use the residual signal of the first neighboring block to predict the residual signal.

The intra residual predictor 810 may generate a first residual signal of the current block based on the second residual signal of the current block and the residual signal of the first neighboring block.

The first residual signal may be a difference between the second residual signal of the current block and the residual signal of the first neighboring block. Alternatively, the first residual signal may be a result of subtracting the residual signal of the first neighboring block from the second residual signal of the current block. The intra residual predictor 810 may generate a difference between the second residual signal of the current block and the residual signal of the first neighboring block as the first residual signal.

The first residual signal may be a residual signal of the current block generated by residual signal prediction. Alternatively, the first residual signal may be a residual signal of the current block generated based on the residual signal of the first neighboring block of the current block.

By applying the residual signal prediction to the second residual signal generated in operation 940, more efficient encoding may be enabled for the current block.

Generation of the first residual signal according to an example will be described in detail with reference to FIG. 31 below.

If it is determined that the residual signal prediction is not to be performed, in operation 960, the intra predictor 120 or the intra residual predictor 810 may generate a third residual signal of the current block.

The third residual signal may be a residual signal of the current block in existing video encoding and / or decoding techniques such as HEVC and AVC. For example, in generating the third residual signal, a method of generating a residual signal of an existing image encoding and / or decoding technique such as HEVC and AVC may be used.

Also, the third residual signal may be the same signal as the second residual signal at step 940. In other words,

steps

940 and 960 can generate the residual signal of the current block in the same manner.

In operation 970, the intra predictor 120 may encode information indicating whether to update the reference sample.

Unlike the existing intra prediction, when the update of the reference sample is performed, the intra prediction unit 120 may determine the above information so that the decoding apparatus 2300, which will be described later, knows whether the reference sample is updated or not. Can be encoded. For example, if the update of the reference sample is used, the value of the information may be set to '1', and if the update of the reference sample is not used, the value of the information may be set to '0'.

For example, the intra prediction unit 120 may indicate whether to update the reference sample using a flag, and may indicate whether to update the reference sample through the flag.

In operation 980, the intra residual prediction unit 810 may encode information indicating whether residual signal prediction is performed.

When the residual signal prediction is performed, the intra residual prediction unit 810 may encode the above information so that the decoding apparatus 2300, which will be described later, may determine whether the residual signal prediction is performed. For example, if the update of the reference sample is used, the value of the information may be set to '1', and if the update of the reference sample is not used, the value of the information may be set to '0'.

For example, the intra prediction unit 120 may indicate whether to update the reference sample using the "intra_residual_prediciton_flag" flag, and may indicate whether to update the reference sample through the flag.

In operation 985, the intra residual predictor 810 may encode an identifier of the first neighboring block.

The identifier of the first neighboring block may be information that enables the neighboring block used for prediction of the residual signal of the current block to be identified.

For example, the identifier of the first neighboring block may indicate a neighboring block used for prediction of the residual signal of the current block among the plurality of neighboring blocks. Alternatively, the identifier of the first neighboring block may be position information indicating the position of the neighboring block used for prediction of the residual signal of the current block among the plurality of neighboring blocks. The position may indicate a position of the selected neighboring block with respect to the current block. The position may indicate a direction in which the selected neighboring block is adjacent to the current block.

The identifier of the first neighboring block may be configured to indicate the same block in both the encoding apparatus 800 and the decoding apparatus 2300. For example, the size N of the block and the position of the neighboring block may be common to the encoding apparatus 800 and the decoding apparatus 2300 in relation to the identifier of the first neighboring block. In order for the encoding apparatus 800 and the decoding apparatus 2300 to share a common configuration with respect to the identifier of the first neighboring block, the identifier of the first neighboring block is "(neighbor-residual_index) truncated unary ( -residual_idx) Truncated unary "" scheme.

When the tank signal prediction is performed, step 990 may be performed after

steps

950, 970, 980, and 980 are performed. In addition, when residual signal prediction is not performed, step 990 may be performed after

steps

960, 970, 980, and 998 are performed.

Next, reference is made to FIG. 17.

In operation 990, the encoding apparatus 800 may perform encoding of the current block by using the residual signal of the current block. Step 990 may be performed by at least one of the transformer 130, the quantizer 140, and the entropy encoder 150.

In operation 990, the residual signal used for encoding the current block may be one of two residual signals.

If it is determined in step 930 to perform the residual signal prediction, the first residual signal of the current block generated in step 950 may be the residual signal used in step 990. In other words, the residual signal generated by the residual signal prediction may be used for encoding the current block, and the encoding apparatus 800 may perform encoding of the current block using the first residual signal of the current block.

If it is determined in step 930 that the residual signal prediction is not to be performed, the third residual signal of the current block generated in step 960 may be the residual signal used in step 990.

Step 990 can include step 991, step 992 and step 993.

In operation 991, the transformer 130 may perform transform on the residual signal to generate transform coefficients.

In operation 992, the quantization unit 140 may generate a quantized transform coefficient level using the transform coefficient.

In operation 993, the entropy encoder 150 may perform entropy encoding on the transform coefficient level.

Among the steps related to the encoding of the above-described information, steps 970, 980 and 985 may be performed by different subjects and different orders than those described above. For example, step 993 may include step 970, step 980 and step 985. In addition, the entro encoder 150 may encode at least one of information indicating whether to update the reference sample, information indicating whether to perform the residual signal prediction, and an identifier of the first neighboring block.

18 is a flowchart of an encoding method according to an embodiment.

Compared to the embodiment described above with reference to FIG. 9, in the embodiment described with reference to FIGS. 18, 19, and 20, the update of the reference sample and the prediction of the residual signal may be performed separately.

First, reference is made to FIG. 18.

In operation 1010, the intra predictor 120 may generate a reference sample of the current block. The intra predictor 120 may generate reference samples around the current block for intra prediction. Generation of a reference sample according to an example will be described in detail with reference to FIG. 22 below.

The encoding apparatus 800 may selectively provide a function of updating a reference sample. If the function of updating the reference sample is used, step 1020 may be performed after step 1010. If the function of updating the reference sample is not used, step 1030 may be performed after step 1010. In other words, in an embodiment, the function of updating the reference sample may be selectively combined.

In operation 1020, the intra predictor 120 may provide a function related to updating a reference sample.

Next, reference is made to FIG. 19.

Referring to FIG. 19, step 1020 may include step 1021, step 1022, and step 1023.

In operation 1021, the intra prediction unit 120 may determine whether to update the reference sample. Here, updating the reference sample may be to reconstruct the sample value of the reference sample used for generation of the prediction block before generating the prediction block of the current block.

If it is determined to perform an update of the reference sample, step 1022 may be performed. If it is determined not to perform the reference sample update, step 1023 may be performed.

In operation 1022, the intra prediction unit 120 may update the value of the reference sample, and may determine the value of the reference sample used to generate the prediction block of the current block through the update.

After step 1022 is performed, step 1023 may be performed.

In operation 1023, the intra prediction unit 120 may encode information indicating whether to update the reference sample.

Unlike the existing intra prediction, when the update of the reference sample is performed, the intra prediction unit 120 may provide the above information so that the decoding apparatus 2300, which will be described later, will know whether the reference sample is updated or not. Can be encoded. For example, if the update of the reference sample is used, the value of the information may be set to '1', and if the update of the reference sample is not used, the value of the information may be set to '0'.

When step 1010 or step 1020 is performed, step 1030 may be performed.

Reference is again made to FIG. 18.

In operation 1030, the intra prediction unit 120 may perform intra prediction. The intra predictor 120 may generate a prediction block of the current block. The intra prediction unit 120 may generate the prediction block of the current block by using the reference sample according to the intra prediction mode for the current block.

The encoding apparatus 800 may selectively provide a function of prediction of the residual signal. If the function of prediction of the residual signal is used, step 1040 may be performed after step 1030. If the function of prediction of the residual signal is not used, step 1050 may be performed after step 1030. In other words, in an embodiment the functions of the prediction of the feast signal may be selectively combined.

When the residual signal of the current block is obtained through intra prediction, the intra residual predictor 120 may perform prediction on the residual signal of the current block by using the residual signal of the neighboring block. Since the residual signal is updated once the residual signal is generated, a "prediction" on the residual signal may be considered as a "reprediction" on the residual signal.

In operation 1040, the intra residual prediction unit 120 may provide a function related to prediction of the residual signal.

Referring to FIG. 20, step 1040 may include step 1041, step 1042, step 1046, and step 1047.

In operation 1041, the intra residual prediction unit 810 may determine whether to perform residual signal prediction.

If it is determined to perform the residual signal prediction, step 1042 may be performed.

If it is determined not to perform residual signal prediction, step 1046 may be performed.

In operation 1042, the intra residual prediction unit 810 may perform prediction of the residual signal.

Step 1042 may include step 1043, step 1044, and step 1045.

At step 1042, step 1043 and step 1044 may be performed.

Steps

1043 and 1044 may be performed in a predefined order. For example, step 1043 may be performed prior to step 1044. Alternatively, step 1044 may be performed before step 1043.

In operation 1043, the intra residual predictor 810 may determine a first neighboring block among one or more neighboring blocks of the current block. The first neighboring block may be a block used for residual signal prediction. Determination of the neighboring block according to an example will be described in detail with reference to FIG. 36 below.

In operation 1044, the intra prediction unit 120 may generate a second residual signal of the current block by using intra prediction. The intra predictor 120 may generate a second residual signal of the current block based on the intra prediction mode and the reference sample for the current block.

When step 1043 and step 1044 are performed as the residual signal prediction is determined to be performed, step 1045 may be performed next.

In operation 1045, the intra residual predictor 810 may generate a first residual signal of the current block according to the residual signal prediction.

By applying the residual signal prediction to the second residual signal generated in step 1044, more efficient encoding may be enabled for the current block.

If it is determined that the residual signal prediction is not to be performed, in operation 1046, the intra predictor 120 or the intra residual predictor 810 may generate a third residual signal of the current block.

In addition, the third residual signal may be the same signal as the second residual signal in step 1044. In other words,

step

1044 and 1046 may generate the residual signal of the current block in the same manner.

Once step 1042 or step 1046 is performed, step 1047 may then be performed.

In operation 1047, the intra residual prediction unit 810 may perform encoding of information related to the residual signal prediction.

When the residual signal prediction is performed, the intra residual prediction unit 810 may encode the above information so that the decoding apparatus 2300, which will be described later, may determine whether the residual signal prediction is performed, with reference to FIG. 21. For example, if the update of the reference sample is used, the value of the information may be set to '1', and if the update of the reference sample is not used, the value of the information may be set to '0'.

Next, reference is made to FIG. 20.

Step 1047 may include step 1048 and step 1049.

In operation 1048, the intra residual prediction unit 810 may encode the identifier of the first neighboring block.

Step 1048 may be omitted. For example, in step 1041, if it is determined that residual signal prediction is not to be performed, step 1048 may be omitted.

In operation 1049, the intra residual prediction unit 810 may encode information indicating whether residual signal prediction is performed.

In step 1047, step 1048 and step 1049 may be performed.

Steps

1043 and 1044 may be performed in a predefined order. For example, step 1048 may be performed prior to step 1049. Alternatively, step 1049 may be performed prior to step 1048.

Once step 1030 or step 1040 is performed, step 1050 may then be performed.

In operation 1050, the encoding apparatus 800 may perform encoding of the current block by using the residual signal of the current block. Step 1050 may be performed by at least one of the transformer 130, the quantizer 140, and the entropy encoder 150.

In operation 1050, the residual signal used for encoding the current block may be one of two residual signals.

If it is determined in step 1041 to perform the residual signal prediction, the first residual signal of the current block generated in step 950 may be the residual signal used in step 1050. In other words, the residual signal generated by the residual signal prediction may be used for encoding the current block, and the encoding apparatus 800 may perform encoding of the current block using the first residual signal of the current block.

If it is determined in step 1050 that the residual signal prediction is not to be performed, the third residual signal of the current block generated in step 1046 may be the residual signal used in step 1050.

Next, reference is made to FIG. 21.

Step 1050 may include step 1051, step 1052, and step 1503.

In operation 1501, the transformer 130 may perform transform on the residual signal to generate transform coefficients.

In step 1052, the quantization unit 140 may generate a quantized transform coefficient level using the transform coefficient.

In operation 1053, the entropy encoder 150 may perform entropy encoding on the transform coefficient level.

Among the steps related to the encoding of the above-described information, steps 1023, 1048, and 1049 may be performed by different subjects and different orders than those described above. For example, step 1053 may include step 1023, step 1048, and step 1049. In addition, the entro encoder 150 may encode at least one of information indicating whether to update the reference sample, information indicating whether to perform the residual signal prediction, and an identifier of the first neighboring block.

Proposed Coding Methods

In the embodiment described above with reference to FIG. 10, the encoding method may be classified into two methods. Each method is as follows.

Method 1: The first method may be a method of generating a reference sample of intra prediction by the existing method and reconstructing the sample value of the reference sample generated by the existing method according to the directional pattern of the surrounding sample. have. Here, the conventional method may mean a method of generating a reference sample for intra prediction, which is performed by the intra prediction unit 120 described above with reference to FIG. 1.

Second Method: The second method may be a method of reducing energy of a residual signal by performing re-prediction using a residual signal of a neighboring block on a residual signal obtained through conventional intra prediction. In other words, in the two-method, re-prediction at the residual signal level can be performed. Here, the conventional method is a process of generating a prediction signal of a current block through spatial prediction with respect to a reference sample, which is performed by the intra prediction unit 120 described above with reference to FIG. And obtaining a residual signal of the block.

Example Classification

The embodiments described above with reference to FIGS. 18, 19, 20, and 21 may be classified into three embodiments. Each embodiment is as follows.

First Embodiment The first embodiment is indicated by an arrow filled in in FIG. 18. The first embodiment may include step 1010, step 1020, step 1030, and step 1050. The first embodiment performs update of the reference sample but may not perform prediction of the residual signal.

Second Embodiment The first embodiment is indicated by an arrow emptied in FIG. 18. The second embodiment may include step 1010, step 1020, step 1030, step 1040, and step 1050. The first embodiment may perform update of a reference sample and prediction of a residual signal.

Third Embodiment The third embodiment is indicated by an arrow with a diagonal line inside in FIG. 18. The third embodiment may include step 1010, step 1030, step 1040 and step 1050. The first embodiment does not update the reference sample, but may perform prediction of the residual signal.

The encoding apparatus 800 may perform encoding of the current block by using one of the first, second, and third embodiments. Alternatively, the encoding apparatus 800 may perform rate-distortion optimization for all three embodiments, and select a method of deriving a minimum rate-distortion value among the three embodiments. For example, the encoding apparatus 800 may selectively use each of

steps

1020 and 1040 to derive a minimum rate-distortion value.

Unit of update of the reference sample.

In operation 910, the intra prediction unit 120 may determine whether to update the reference sample for each predefined unit. The predefined unit may be at least one of 1) the entire image sequence (ie, video), 2) one image (ie, picture), 3) slice, and 4) coding unit.

For the predefined unit, reference sample update information may be used to indicate whether update of the reference sample is performed. The reference sample update information may be information indicating whether the update of the reference sample has been performed on the predefined unit. For example, the value of the reference sample update information may indicate that the update of the reference sample has been performed in encoding of the current block. When the value of the reference sample update information is the second value, it may represent that the update of the reference sample has not been performed in encoding of the current block.

The encoding apparatus 800 may include the encoded residual signal prediction information in the bitstream. The decoding apparatus 2300 may determine whether to perform the residual signal prediction on the current block by using the residual signal prediction information.

In the following, an update of the reference sample for each of the predefined units is described.

1) The entire image sequence: Whether to update the reference sample may be determined for the entire image sequence. In this case, the sequence parameter set may include reference sample update information. If the reference sample update information of the sequence parameter set indicates that the update of the reference sample is performed, the intra predictor 120 may perform intra prediction using the reference sample to which the gradient according to the direction is applied to the entire image sequence.

2) One image: Whether to update the reference sample may be determined for each image. In this case, the picture parameter set may include reference sample update information. When the reference sample update information of the picture parameter set indicates that the update of the reference sample is performed, the intra predictor 120 performs intra prediction using the reference sample to which the gradient according to the directionality is applied to the entire image corresponding to the picture parameter set. Can be done. Alternatively, the intra predictor 120 may identify whether the update of the reference sample is performed using a picture parameter set identifier (ID) specified in the slice header.

3) Slice: One image may be divided into a plurality of slice segments or a plurality of tiles in one slice segment. Whether to update the reference sample may be determined for each slice. In this case, the slice segment header may include reference sample update information. If the reference sample update information of the slice segment header indicates that the update of the reference sample is performed, the intra prediction unit 120 may perform intra prediction using the reference sample to which the gradient according to the direction is applied to the slice corresponding to the slice segment header. Can be.

4) Coding Unit: Whether to perform update of the reference sample may be determined for each coding unit. In such a case, reference sample update information may exist for the coding unit. If the reference sample update information for the coding unit indicates that the coding unit is updated, the intra prediction unit 120 performs intra prediction using the reference sample to which the gradient according to the direction is applied to the coding unit corresponding to the reference sample update information. Can be done.

As described above, the reference sample update information may be encoded in a sequence parameter set, a picture parameter set, or a slice segment header. In addition, the update information may be encoded for the coding unit.

Residual Unit of signal prediction

Whether to perform the residual signal prediction determined in operation 930 may be determined for the predefined unit. The predefined unit may be at least one of 1) the entire image sequence (ie, video), 2) one image (ie, picture), 3) slice, and 4) coding unit.

The residual signal prediction information may be information indicating whether the residual signal prediction has been performed on the predefined unit. For example, when the value of the residual signal prediction information is the first value may indicate that the residual signal prediction has been performed in encoding of the current block. When the value of the residual signal prediction information is the second value, it may represent that the residual signal prediction has not been performed in encoding of the current block.

In the following, residual signal prediction for each of the predefined units is described.

1) Overall Image Sequence: Whether to perform residual signal prediction may be determined for the entire image sequence. In this case, the sequence parameter set may include residual signal prediction information. If the residual signal prediction information of the sequence parameter set indicates that residual signal prediction is performed, the intra residual prediction unit 810 may perform residual signal prediction on the entire image sequence.

2) One image: Whether to perform the residual signal prediction may be determined for each image. In this case, the picture parameter set may include residual signal prediction information. If the residual signal prediction information of the picture parameter set indicates that the residual signal prediction is performed, the intra residual prediction unit 810 may perform the residual signal prediction on the entire image corresponding to the picture parameter set.

3) Slice: One image may be divided into a plurality of slice segments or a plurality of tiles in one slice segment. Whether to perform the residual signal prediction may be determined for each slice. In this case, the slice segment header may include residual signal prediction information. If the residual signal prediction information of the slice segment header indicates that the residual signal prediction is performed, the intra residual prediction unit 120 may perform the residual signal prediction on the slice corresponding to the slice segment header.

4) Coding Unit: Whether to perform residual signal prediction may be determined for each coding unit. In this case, residual signal prediction information may exist for the coding unit. If the residual signal prediction information for the coding unit indicates that the coding unit is updated, the intra residual prediction unit 810 may perform the residual signal prediction on the coding unit corresponding to the residual signal prediction information.

As described above, the residual signal prediction information may be encoded in a sequence parameter set, a picture parameter set, or a slice segment header. In addition, the update information may be encoded for the coding unit.

22 illustrates a current block and a reference sample according to an example.

Processing for the reference sample, which will be described below, may be used to determine the value of the reference sample prior to the update of the reference sample, and by the intra prediction unit 120 prior to step 910 described above with reference to FIG. Can be performed. In addition, the processing for the reference sample to be described below may correspond to step 1010 described above with reference to FIG. 18.

In FIG. 22, current block 1100, top adjacent line 1110, left adjacent line 1120 and top left sample 1130 are shown.

The reference sample of the current block 1100 may include a top adjacent line 1110, a left adjacent line 1120, and a left top sample 1130. Alternatively, the reference sample of the current block 1100 may be at least some of the samples of the upper adjacent line 1110, the left adjacent line 1120, and the upper left sample 1130. The intra predictor 120 may select at least some of the pixels of the upper neighbor line 1110, the left neighbor line 1120, and the upper left sample 1130 as reference samples according to an intra prediction mode for the current block.

The top adjacent line 1110 may be a horizontal line adjacent to the top of the current block 1100. The left adjacent line 1120 may be a vertical line adjacent to the left side of the current block 1100. The upper left sample 1130 may be a sample adjacent to the upper left side of the current block 1100.

The x coordinate of the leftmost sample of the top adjacent line 1110 may be the same as the x coordinate of the leftmost pixel (s) of the current block 1100. When the size of the current block 1100 is N × N, the length of the upper adjacent line 1110 may be 2N. Here, N may be an integer of 1 or more. Top adjacent line 1010 may be 2N × 1 pixels.

The y coordinate of the top sample of the left adjacent line 1120 may be the same as the y coordinate of the top pixel (s) of the current block 1100. When the size of the current block 1000 is N × N, the length of the left adjacent line 1120 may be 2N. The left adjacent line 1120 may be pixels of 1 × 2N.

The x coordinate of the upper left sample 1130 may be a value obtained by subtracting 1 from the x coordinate of the leftmost pixel (s) of the current block 1100. The y coordinate of the upper left sample 1130 may be a value obtained by subtracting 1 from the y coordinate of the top pixel (s) of the current block 1100.

The aforementioned reference sample can be used in intra prediction for the current block.

The reference sample used for intra prediction may have a brightness value reconstructed by prediction and reconstruction, not a brightness value of pixel (s) of the original image. For example, the neighboring block (s) of the current block 1100 may be encoded prior to encoding of the current block 1100, and brightness values of pixels of the neighboring blocks may be restored through prediction and reconstruction in the encoding process. Can be. The reference sample may be some of the pixels of these peripheral blocks. Also, the brightness value of the reference sample may be a value before the post-processing filtering is applied.

If no reference samples are available around the current block 1100, the intra predictor 120 uses the samples closest to the current block 1100 among the available samples (ie, pixels) in the vicinity. Padding may be performed. The brightness value of the reference sample may be generated by the reference sample padding.

The intra predictor 120 may perform reference sample filtering to reduce the prediction error caused by the quantization error according to the size of the current block 1100, the intra prediction mode, and the like.

In FIG. 23, a circle may represent a sample (or a pixel). The dotted rectangle may represent a block.

In FIG. 23, a current block 1210, a reference sample block 1220, reference samples 1221, and a neighboring block 1230 are shown.

The current block is shown as a block having a size of 4x4. The size of the block may mean the width and height of the block.

The reference sample block 1220 may be a block that includes the reference samples 1221 used for the current block 1210. The reference sample block 1120 may be a block adjacent to the current block 1210 and having the same size as that of the current block 1210.

Reference samples 1221 are shown to have values of I ', J', K ', and L', respectively, through update of the reference sample. The illustrated reference samples may be samples configured according to a method of generating a reference sample among samples around the current block according to the intra prediction mode.

In FIG. 23, reference samples generated by the intra prediction unit 120 are illustrated when the intra prediction mode for the current block 1210 is a horizontal prediction mode.

The dotted line in the peripheral block 1230 may represent a horizontal line of samples in the peripheral block 1230. The thick solid line in the peripheral block 1230 may indicate the inclination of the samples included in the horizontal line. ∇ dx may represent an inclination value.

In FIG. 23, in the horizontal line of samples, an example is shown in which the sample value constantly increases from left to right and then decreases constantly.

The neighboring block 1230 may be a block in which reconstruction has already been completed before encoding and / or decoding of the current block 1210.

The neighboring block used for updating the reference sample may be different from the neighboring block used for intra residual prediction of the current block. As described above with reference to FIGS. 16 and 20, a neighboring block used for intra residual prediction of the current block may be referred to as a first neighboring block. In addition, the neighboring block used for updating the reference sample may be referred to as a second block. The first peripheral block and the second peripheral block may be identical to each other or may be different from each other. Also, the first neighboring block may include the second neighboring block, or the second neighboring block may include the first neighboring block.

For example, when the intra prediction mode is the horizontal prediction mode, the reference sample may be a sample adjacent to the left side of the current block 1210. Or, the reference sample may be a sample of the vertical line adjacent to the left side of the current block 1210. The reference sample block 1220 may be a block adjacent to the left side of the current block 1210. Also, the neighboring block 1230 may be a block obtained by adding the upper neighboring block of the current block 1210 and the upper left neighboring block of the current block 1210. The top adjacent block of the current block 1210 may be a block adjacent to the top of the current block 1210. The upper left neighboring block of the current block 1210 may be a block adjacent to the upper left of the current block 1210. The upper adjacent block and the upper left adjacent block may be adjacent to each other.

When the size of the current block 1210 is NxN, the size of the upper neighboring block and the size of the upper left neighboring block may be NxN, respectively, and the size of the neighboring block 1230 may be 2NxN. In FIG. 23, the size of the neighboring block is shown to be 8 × 4.

In addition, when the size of the current block 1210 is NxN, the size of the upper neighboring block and the size of the upper left neighboring block may be aNxbN, respectively, and the size of the neighboring block 1230 may be 2aNxbN. Here, a and b may each be a real number.

In addition, the upper neighboring block, the upper left neighboring block, and the neighboring block 1230 may each have a size determined by a predefined size or a predefined manner.

The intra prediction unit 120 of the encoding apparatus 800 and the intra prediction unit 240 of the decoding apparatus 2300 to be described below may use upper neighboring blocks, upper left neighboring blocks, and neighboring blocks of the same size. The encoding apparatus 800 may set respective sizes of the upper neighboring block, the upper left neighboring block, and the neighboring block 1230. The size of the upper neighboring block, the size of the upper left neighboring block, and the size of the neighboring block 1230 may be equally used in the decoding apparatus 2300. The set size may be transmitted from the encoding apparatus 800 to the decoding apparatus 2300 through a bitstream.

Update of the reference sample may be considered to be a reconstruction of a reference sample around the current block for intra prediction.

When intra prediction is performed on the second neighboring block, the current block may also be composed of a texture having a similar direction to the texture of the second neighboring block according to the spatial correlation. In order to reflect this directionality, the intra prediction unit 120 may update the value of the reference sample required for intra prediction before performing intra prediction on the current block.

The intra predictor 120 may reconstruct the reference sample to be similar to the sample of the current block by using a directional gradient pattern according to the direction of the second neighboring block.

In operation 915 described above with reference to FIG. 9 and operation 1022 described above with reference to FIG. 10, the intra predictor 120 may detect an inclination pattern of the second neighboring block and calculate an inclination. . An inclination pattern detection method according to an example will be described in detail with reference to FIG. 24 below.

In operation 915 described above with reference to FIG. 9 and operation 1022 described above with reference to FIG. 10, the intra predictor 120 may detect gradient patterns of rows of the second neighboring block. The intra predictor 120 may check whether the slope patterns of the rows of the second neighboring block are the same. When the slope patterns of the rows of the second neighboring block are the same, the intra predictor 120 may calculate the slope of the second neighboring block. Here, the inclination of the second peripheral block may be the inclination of one selected row of the second peripheral block. For example, the inclination of the second neighboring block may be the inclination of the row adjacent to the current block 1210 among the rows of the second neighboring block. The intra predictor 120 may determine the inclination of the row adjacent to the current block 1210 among the rows of the second neighboring block as the final inclination of the second neighboring block.

In addition, in

steps

915 and 1022, the intra prediction unit 120 may determine or update the value of the reference sample based on the neighboring block of the current block. The intra predictor 120 may determine or update the value of the reference sample based on the slope pattern of the second neighboring block.

The value of the reference sample may be changed from the value before the update to the value after the update by the intra predictor 120, and the value before the update of the reference sample is predicted and restored as the reference sample block 1220 including the reference sample is predicted. It may be a generated value. In other words, as the reference sample block 1220 is predicted and reconstructed, the value of the reference sample may be determined, and the determined value may be used as the value before the update in the update of the reference sample. In prediction and reconstruction of a reference sample, a prediction and reconstruction method of an existing image encoding and / or decoding technique such as HEVC and AVC may be used.

When the gradient ∇ dx is calculated, the intra predictor 120 may determine or update the value of the reference sample in a predefined manner.

For example, when the intra prediction mode is the horizontal prediction mode, the intra prediction unit 120 may determine or update the value of the reference sample in the same manner as in Equation 2 below.

[Equation 2]

I '= I - w * f (▽ dx )

J '= J - w * f (▽ dx )

K '= K - w * f (▽ dx )

L '= L - w * f (▽ dx )

f can represent a function. w may represent a weight. I may be a value before updating of the topmost sample of reference samples 1221. I ′ may be a value after updating of the uppermost sample. J , K , L may also be the value before the update of the corresponding reference sample. J ', K ', and L 'may be values after updating of the corresponding reference sample.

As described in Equation 2, the intra prediction unit 120 reconstructs the reference samples I ', J ', K that are reconstructed by reflecting the deduction according to the gradient with respect to the existing reference samples I , J , K, and L. 'And L ' can be generated. In addition, the intra prediction unit 120 may consider the weighting factor w in updating the value of the reference sample. The intra predictor 120 may update the value of the reference sample by subtracting the product of the value determined based on the slope ∇ dx and the predefined weight factor w from the value before updating the reference sample. By updating, the value of the reference sample may be reduced by w * f (∇ dx ).

The reference sample may be plural. The weight factor w may be the same for a plurality of reference samples. Alternatively, the weight factors w may be different from each other for each of the plurality of reference samples. For example, the weight factor w may differ for each reference sample of the plurality of reference samples for each reference sample. The location of the reference sample may be a location relative to the current block 1210.

The intra predictor 120 may combine the aforementioned update method of the reference sample and the existing method. For example, when the intra prediction unit 120 performs the update of the reference sample described above with reference to FIG. 18, in operation 1110, the intra prediction unit 120 may not perform padding of the reference pixel. In addition, when the intra prediction unit 120 performs the update of the reference sample described above with reference to FIG. 18, in operation 1110, the intra prediction unit 120 may not perform smoothing using a low pass filter. .

As described above with reference to FIG. 13, the second neighboring block may be selected based on the location of the current block. For example, the intra predictor 120 may select, as the second neighboring block, a block having a predetermined position according to an intra prediction mode among blocks reconstructed based on the position of the current block. In addition, the intra predictor 120 may analyze the slope pattern of the selected second neighboring block.

As described above with reference to FIG. 23, the size of the second neighboring block may be determined based on the size of the current block. For example, if the size of the current block is NxN, the size of the second neighboring block may be 2N * N. The encoding apparatus 800 may set the size of the second neighboring block. The set size may be equally used in the decoding device 2300. The set size may be transmitted from the encoding apparatus 800 to the decoding apparatus 2300 through a bitstream.

One line of the second peripheral block is shown in FIG. 24. The line may be a row or a column of neighboring blocks. In FIG. 23, the size of the second peripheral block is shown as 8 × 4, and in FIG. 24, one line of the second peripheral block is shown as 8 × 1.

The intra predictor 120 may calculate one or more sample inclinations for each line. Each sample slope of the one or more sample slopes may be a slope between two adjacent samples of the line. Since one line may include a plurality of samples, the intra predictor 120 may obtain a plurality of sample gradients with respect to the line. As an example of one or more sample inclinations, in FIG. 24, ∇ dx 1, ∇ dx 2, ∇ dx 3, ∇ dx 4, ∇ dx 5, ∇ dx 6, and dx dx 7 are shown. For example, ∇ dx 1 may be the slope between the first sample and the second sample of the line.

The intra predictor 120 may calculate at least one sample slope of each line of each line of the second neighboring block.

The intra predictor 120 may calculate the line slope based on one or more sample slopes. For example, the line slope may be 1) an intermediate value of one or more sample gradients, 2) an average value of one or more sample gradients, or 3) a predefined representative value of one or more sample gradients.

The predefined representative value may always have a positive value.

When the median value of one or more sample inclinations is used as the line inclination, Equation 3 below may be used.

[Equation 3]

f (▽ dx ) = median (| dx ₁ ｜, dx ₂ ｜, dx ₃ ｜, dx ₄ ｜, dx ₅ ｜, dx ₆ ｜, dx ₇ ｜

∇ dx may represent the slope line.

The intra predictor 120 may apply a weight for each of the sample inclinations to the one or more sample inclinations in calculating the line inclination.

In the above-described manner, the intra predictor 120 may calculate one or more line slopes of one or more lines of the second neighboring block.

When the line slope is calculated, the intra predictor 120 may calculate the slope of the second neighboring block based on one or more line slopes. For example, the slope of the second peripheral block may be 1) an intermediate value of one or more line slopes, 2) an average value of one or more line slopes, or 3) a predefined representative value of one or more line slopes. Alternatively, the intra predictor 120 may apply a weight for each of the line slopes to one or more line slopes in calculating the slope of the second neighboring block.

The calculated slope of the second peripheral block can be used as the final slope for updating the reference sample.

For example, as shown in FIG. 24, when the sample slopes of the line increase and decrease, each of I, J, K, and L that have already been generated as reference samples 1221 of the current block 1210 of FIG. 23. The updated reference samples I ', J', K 'and L' can be obtained by subtracting the line slope of the line from.

As described above with respect to the sample inclination, the line inclination and the inclination of the second neighboring block, the intra predictor 120 may incline between two adjacent reference samples among the plurality of reference samples belonging to one row of the second neighboring block. The value of the reference sample can be determined based on the value.

Alternatively, the intra predictor 120 may use the line slope of one line as the slope of the reference sample corresponding to the line. For example, lines and reference samples having the same relative position may correspond to each other. For example, the intra predictor 120 may use the line slope of the uppermost line of the one or more lines to update the uppermost reference sample of the one or more reference samples. Alternatively, the intra predictor 120 may use the line slope of the line adjacent to the current block 1210 among one or more lines for updating the reference sample.

The intra predictor 120 may select only some line (s) of the entire lines of the second neighboring block in calculating the slope of the second neighboring block. The intra predictor 120 may calculate the slope of the second neighboring block by using the line slope (s) of the selected part of the line (s). The intra predictor 120 may select the line (s) of the predefined position (s) or the predetermined number of line (s) of the entire lines of the second neighboring block. The intra predictor 120 may set a method of selecting only some line (s) of the entire lines of the second neighboring block. The set method may be transmitted from the encoding apparatus 800 to the decoding apparatus 2300 through a bitstream.

The intra predictor 120 may select only some of the samples of the entire line of the line in calculating the line slope of the line. In other words, one or more sample slopes of each line need not necessarily be calculated for the entire samples of each line. The intra predictor 120 may calculate a line slope for each of areas that are symmetrical with respect to the dotted line in the middle of FIG. 23. For example, the intra predictor 120 may calculate one or more sample inclinations of each line with respect to half of the samples on the left side of each line, and calculate the line inclination based on the calculated one or more sample inclinations. . In addition, the intra predictor 120 may calculate one or more sample inclinations of each line with respect to the samples of the right half of each line, and calculate the line inclination based on the calculated one or more sample inclinations.

The intra predictor 120 may calculate one or more sample inclinations of each line with respect to the selected samples among the samples of each line, and calculate the line inclination based on the calculated one or more sample inclinations. Can be. In the calculation of the line slope, the size of the line (or the number of samples) may be larger or smaller than the width 2N of the second peripheral block. The intra predictor 120 may calculate the line slope of the line using the sample slope (s) between selected samples. The intra predictor 120 may select samples of predefined positions or a predetermined number of samples among the samples of the entire line. The intra predictor 120 may set a method of selecting only some samples of the entire samples of the line. The set method may be transmitted from the encoding apparatus 800 to the decoding apparatus 2300 through a bitstream.

The intra predictor 120 may select some reference sample (s) to which the update is to be applied from among all reference samples of the current block. The intra predictor 120 may select the number of reference sample (s) to which the update is to be applied among the reference samples of the entire current block. For example, the intra predictor 120 may update only some of the reference samples 1221 of FIG. 23.

The intra predictor 120 may select some reference sample (s) to which an update is to be applied among all reference samples of the current block according to the characteristics of the current block. In addition, the intra predictor 120 may determine the number of some reference sample (s) to which the update is to be applied among all reference samples of the current block according to the characteristics of the current block.

For example, the characteristic of the current block may be the size of the current block. The intra prediction unit 120 may select some reference sample (s) to which the update is to be applied among the reference samples of the entire current block using different methods according to the size of the current block.

For example, considering the case where the size of the current block is relatively large, such as 16x16 and 32x32, the larger the size of the current block, the greater the number of reference samples of the current block. As the number of reference samples increases, the correlation for the tilt pattern according to the direction may decrease relatively. In this case, the encoding apparatus 800 may determine the number of reference samples to update based on the slope.

The method of selecting some reference sample (s) to apply the update among the reference samples and the number of some reference sample (s) to apply the update among the reference samples from the decoding apparatus from the encoding apparatus 800 through the bitstream It may be transmitted to (2300).

In FIG. 25, a circle may represent a sample (or pixel). The dotted rectangle may represent a block.

In FIG. 25, a current block 1410, a reference sample block 1420, reference samples 1421, and a neighboring block 1430 are shown.

Reference sample block 1420 may be a block that includes reference samples 1421 used for current block 1410. The reference sample block 1420 may be a block adjacent to the current block 1410 and having the same size as that of the current block 1410.

Reference samples 1421 are shown to have values of A ', B', C ', and D', respectively, through update of the reference sample. The illustrated reference samples may be samples configured according to a method of generating a reference sample among samples around the current block according to the intra prediction mode.

In FIG. 25, reference samples generated by the intra prediction unit 120 are illustrated when the intra prediction mode for the current block 1310 is the vertical prediction mode.

The dotted line in the peripheral block 1430 may represent a vertical line of pixels in the peripheral block 1430. The thick solid line in the peripheral block 1430 may indicate the inclination of the samples included in the vertical line. ∇ dx may represent an inclination value.

In FIG. 25, an example is shown in which a sample value increases constantly from top to bottom in a vertical line of samples and then decreases constantly.

The neighboring block 1430 may be a block in which reconstruction has already been completed before encoding and / or decoding of the current block 1410.

The neighboring block used for updating the reference sample may be different from the neighboring block used for intra residual prediction of the current block. As described above with reference to FIG. 16, a neighboring block used for intra residual prediction of the current block may be referred to as a first neighboring block. In addition, the neighboring block used for updating the reference sample may be referred to as a second block. The first peripheral block and the second peripheral block may be identical to each other or may be different from each other. Also, the first neighboring block may include the second neighboring block, or the second neighboring block may include the first neighboring block.

For example, when the intra prediction mode is the vertical prediction mode, the reference sample may be a sample adjacent to the top of the current block 1410. Alternatively, the reference sample may be a sample of the horizontal line adjacent to the top of the current block 1410. The reference pixel block 1420 may be a block adjacent to the top of the current block 1 $ 10. In addition, the neighboring block 1330 may be a block obtained by adding the sin side block of the current block 1410 and the upper left adjacent block of the current block 1410. The left adjacent block of the current block 1410 may be a block adjacent to the left of the current block 1410. The upper left adjacent block of the current block 1410 may be a block adjacent to the upper left of the current block 1410. The left adjacent block and the upper left adjacent block may be adjacent to each other.

When the size of the current block 1410 is NxN, the size of the left neighboring block and the size of the upper left neighboring block may be NxN, respectively, and the size of the neighboring block 1430 may be Nx2N. In FIG. 22, the size of the neighboring block is shown to be 8 × 4.

In addition, when the size of the current block 1410 is NxN, the size of the upper neighboring block and the size of the upper left neighboring block may be aNxbN, respectively, and the size of the neighboring block 1430 may be aNx2bN. Here, a and b may each be a real number.

In addition, the upper neighboring block, the upper left neighboring block, and the neighboring block 1430 may each have a size determined by a predefined size or a predefined manner.

The intra prediction unit 120 of the encoding apparatus 800 and the intra prediction unit 240 of the decoding apparatus 2300 to be described below may use upper neighboring blocks, upper left neighboring blocks, and neighboring blocks of the same size. The encoding apparatus 800 may set respective sizes of the upper neighboring block, the upper left neighboring block, and the neighboring block 1430. The size of the upper neighboring block, the size of the upper left neighboring block, and the size of the neighboring block 1430 may be equally used in the decoding apparatus 2300. The set size may be transmitted from the encoding apparatus 800 to the decoding apparatus 2300 through a bitstream.

The intra predictor 120 may update the reference sample to be similar to the sample of the current block by using the gradient pattern according to the direction of the second neighboring block.

In operation 915 described above with reference to FIG. 9 and operation 1022 described above with reference to FIG. 10, the intra predictor 120 may detect an inclination pattern of the second neighboring block and calculate an inclination. .

In operation 915 described above with reference to FIG. 9 and operation 1022 described above with reference to FIG. 10, the intra predictor 120 may detect gradient patterns of columns of the second neighboring block. The intra predictor 120 may check whether the gradient patterns of the columns of the second neighboring block are the same. When the slope patterns of the columns of the second neighboring block are the same, the intra predictor 120 may calculate the slope of the second neighboring block. Here, the inclination of the second peripheral block may be the inclination of one selected row of the second peripheral block. For example, the slope of the second peripheral block may be the slope of a column adjacent to the current block 1410 among the columns of the second peripheral block. The intra predictor 120 may determine a slope of a column adjacent to the current block 1410 among the columns of the second neighboring block as the final slope of the second neighboring block.

In addition, in

steps

The value of the reference sample may be changed from the value before the update to the value after the update by the intra predictor 120, and the value before the update of the reference sample is predicted and restored as the reference sample block 1420 including the reference sample is predicted. It may be a generated value. In other words, as the reference sample block 1420 is predicted and reconstructed, the value of the reference sample may be determined, and the determined value may be used as the value before the update in the update of the reference sample. In prediction and reconstruction of a reference sample, a prediction and reconstruction method of an existing image encoding and / or decoding technique such as HEVC and AVC may be used.

For example, when the intra prediction mode is the vertical prediction mode, the intra prediction unit 120 may determine or update the value of the reference sample in the same manner as in Equation 4 below.

[Equation 4]

A '= A + w * f (▽ dx )

B '= B + w * f (▽ dx )

C '= C + w * f (▽ dx )

D '= D + w * f (▽ dx )

f can represent a function. w may represent a weight. A may be a value before updating of the topmost sample of the reference samples 1421. A ′ may be a value after updating of the uppermost sample. B , C , D may also be the value before the update of the corresponding reference sample. B ′, C ′, and D ′ may be values after updating of the corresponding reference sample.

As described in Equation 4, the intra prediction unit 120 reconstructs the reference samples A ', B ', and C which are reconstructed by reflecting the deduction according to the gradient with respect to the existing reference samples A , B, C, and D. 'And D ' can be generated. In addition, the intra prediction unit 120 may consider the weighting factor w in updating the value of the reference sample. The intra predictor 120 may update the value of the reference sample by adding the product of the value determined based on the slope ∇ dx and the predefined weight factor w to the value before updating the reference sample. The update may increase the value of the reference sample by w * f ( f dx ).

The reference sample may be plural. The weight factor w may be the same for a plurality of reference samples. Alternatively, the weight factors w may be different from each other for each of the plurality of reference samples. For example, the weight factor w may differ for each reference sample of the plurality of reference samples for each reference sample. The position of the reference sample may be a position relative to the current block 1410.

The intra predictor 120 may combine the aforementioned update method of the reference sample and the existing method. For example, when the intra prediction unit 120 performs the update of the reference sample described above with reference to FIG. 18, in operation 1010, the intra prediction unit 120 may not perform padding of the reference pixel. In addition, when performing the update of the reference sample described above with reference to FIG. 18, the intra predictor 120 may not perform smoothing using a low frequency filter in step 1010.

Types of Slope Patterns

The inclination pattern for the directionality described above with reference to FIGS. 23 to 25 may be classified into predefined types. For example, the slope pattern can be 1) increase, 2) decrease, 3) increase and saturation, 4) decrease and saturation, 5) saturation and increase, 6) saturation and decrease, 7) Symmetry of increase and decrease and 8) symmetry of decrease and increase. In the following, the above-described types will be described.

1) "increase" refers to a tilt pattern in which the values of the samples increase with direction. The direction may be from left to right. Alternatively, the direction may be from top to bottom.

2) “decrease” may indicate an inclined pattern in which the values of the samples increase with direction.

3) "Increase and saturation" may indicate a gradient pattern in which the values of the samples increase in the front part and the values of the samples remain constant in the rear part along the direction.

4) "Decrease and Saturation" may indicate a gradient pattern in which the values of the samples decrease in the front part and the values of the samples remain constant in the rear part along the direction.

5) "Saturation and increase" may indicate an inclined pattern in which the values of the samples remain constant in the front part and the values of the samples increase in the rear part along the direction.

6) "Saturation and Reduction" may indicate an inclined pattern in which the values of the samples remain constant in the front part and the values of the samples decrease in the rear part along the direction.

7) "symmetry of increase and decrease" may indicate a symmetrical inclination pattern in which the values of the samples increase in the front part and the values of the samples decrease in the back part along the direction.

8) "symmetry of decrease and increase" may refer to an oblique pattern of symmetry, in which the value of the samples decreases in the front part and the value of the samples increases in the back part along the direction.

The "increase" described above may be a constant increase or a non-constant increase. In addition, the "reduction" described above may be a constant decrease, or may be a non-uniform decrease.

The intra predictor 120 may determine the value of the reference sample according to the type of the slope pattern of the second neighboring block of the current block. For example, when the gradient pattern is one of "increase", "decrease", "increase and saturation", "decrease and saturation", "saturation and increase" and "saturation and decrease", the intra prediction unit 120 The value of the reference sample can be determined based on the slope value of the line of "increase" or the slope value of the line of "decrease".

When the gradient pattern is “symmetrical”, the intra predictor 120 may determine the value of the reference sample based on the gradient values of two lines symmetrical of the gradient pattern. For example, as described above with reference to FIG. 22, when the type of the inclination pattern is symmetric that decreases after increasing, the update of Equation 2 may be applied. For example, the intra predictor 120 may update the value of the reference sample by subtracting the product of the value determined based on the slope ∇ dx and the predefined weight w from the value before the update of the reference sample. By updating, the value of the reference sample may be reduced by w * f (∇ dx ). For example, as described above with reference to FIG. 24, when the type of the inclination pattern is symmetric that increases after reduction, the update of Equation 3 may be applied. For example, the intra predictor 120 may update the value of the reference sample by adding the product of the value determined based on the slope ∇ dx and the predefined weight w to the value before updating the reference sample. The update may increase the value of the reference sample by w * f ( f dx ).

Use of Coding Parameters to Detect Gradient Patterns

In addition to the above-described embodiment, the intra predictor 120 may detect the gradient pattern by using an encoding parameter. For example, the encoding parameter may include: 1) syntax defined in relation to intra prediction, 2) coding variable, 3) current coding unit, 4) prediction unit, 5) size of transform unit, and 6) encoding. Whether or not the unit is divided. For example, the intra predictor 120 may determine a value related to a neighboring block by using an encoding parameter. The peripheral block may be the peripheral block 1230 described above with reference to FIG. 23 or the peripheral block 1430 described above with reference to FIG. 25. The value related to the neighboring block may include the size of the neighboring block. The intra predictor 120 may determine the slope of the neighboring block by using an encoding parameter. The intra predictor 120 may determine a range of a reference sample to which the update is applied using an encoding parameter. In addition, the intra predictor 120 may determine a weight factor using an encoding parameter.

Extended use of slope

The intra predictor 120 may apply the slope of the neighboring block to the pixel value of the prediction block, not the reference sample. The intra predictor 120 may fix the value of the reference sample and may update the pixel value of the prediction block by using the slope of the neighboring block. By directly updating the pixel value of the prediction block, the same effect as when updating the value of the reference sample can be obtained.

In the above-described embodiment, the update made to the reference sample according to the slope of the neighboring block may be equally applied to the prediction block. For example, an update made on one row of reference samples may be equally applied to each row of a plurality of rows of the prediction block. Or, for example, an update made on one column of reference samples may be equally applied to each column of the plurality of columns of the prediction block. As for the update of the intra prediction unit 120 prediction block, the encoding parameters can be used in the same manner as used for the update of the reference sample. In other words, the intra prediction unit 120 may update the pixel value of the prediction block based on the encoding parameter.

27 shows intra prediction with 65 respective modes according to an example.

In operation 920 described above with reference to FIG. 16 and operation 1030 described above with reference to FIG. 18, the intra prediction unit 120 may generate a prediction block of the current block by performing intra prediction on the current block. have. In performing intra prediction on the current block, the intra prediction unit 120 may use the updated (or reconstructed) reference sample (s). The intra predictor 120 may generate the prediction block of the current block by using the updated (or reconstructed) reference sample (s).

The intra predictor 120 may configure neighboring reference sample (s) for the current block by updating the aforementioned reference sample. The intra predictor 120 may generate one or more prediction blocks of the current block for one or more intra modes. One or more intra modes may include an angular mode.

The intra predictor 120 may determine a prediction block having a minimum rate-distortion value with respect to one or more prediction blocks. The intra predictor 120 may select an intra mode corresponding to the prediction block as the final intra prediction mode. Alternatively, the intra predictor 120 may select an intra mode for generating a prediction block having a minimum rate-distortion value among one or more intra modes as a final intra prediction mode.

In FIG. 26, intra modes having 33 respective modes are illustrated. In FIG. 27, intra modes having 65 respective modes are illustrated. In addition, mode 0 may indicate a planner mode. Mode 1 may indicate a DC mode.

28 is a view illustrating an area of an image according to an example.

In FIG. 28, a portion 1600 of the image is shown. A portion 1600 of the illustrated image may include a current block 1610, a neighboring block 1620, a reconstructed region 1630, a neighboring block reference sample 1631, and a current block reference sample 1632.

The neighbor block reference sample 1631 may be a reference sample used when performing intra prediction on the neighbor block. The current block reference sample 1632 may be a reference sample used when performing intra prediction on the current block.

The sample value of the neighboring block reference sample 1631 may be an updated value when the update of the reference sample of

steps

915 and 1022 is performed on the neighboring block 1620.

The sample value of the current block reference sample 1632 may be an updated value when an update of the reference samples of

steps

915 and 1022 is performed for the current block 1610.

The current block 1610, the neighboring block 1620, the neighboring block reference sample 1631, and the current block reference sample 1632 illustrated in FIG. 28 are an intra prediction mode of the neighboring block 1620 and an intra of the current block 1610. When the prediction modes are all vertical prediction modes, the relative position may be indicated. For example, when the intra prediction mode is the vertical prediction mode, the first neighboring block described in FIGS. 16 and 20 may be a left neighboring block of the current block. The reference sample of the current block may be pixel (s) in a horizontal line adjacent to the top of the current block. Also, the reference sample of the peripheral block may be pixel (s) in the horizontal line adjacent to the top of the peripheral block.

In FIG. 29, the neighboring block 1710, the prediction block 1720 of the neighboring block, and the residual signal 1730 of the neighboring block are illustrated. In Figure 29, the _{neighboring blocks} Intra _{_ residual signal} in the residual signal of the neighboring blocks has been described in the form of a matrix expression.

The peripheral block 1710 may correspond to the first peripheral block described above with reference to FIGS. 16 and 20. Alternatively, the peripheral block 1710 may correspond to the peripheral block 1620 described above with reference to FIG. 28.

The residual signal 1730 may correspond to the "residual signal of the first peripheral block" described above with reference to FIGS. 16 and 20.

As shown in FIG. 29, the residual signal 1730 may be a difference between the neighboring block 1710 and the prediction block 1720. Alternatively, the residual signal 1730 may be a result of subtracting the prediction block 1720 from the neighboring block 1710.

The value of the prediction block 1720 may be determined based on the intra prediction mode for the neighboring block 1710.

For example, as illustrated in FIG. 29, when the intra prediction mode of the neighboring block 1710 is the vertical prediction mode, the value of each row of the prediction block 1720 may be the value of the reference pixels of the neighboring block 1710. . In other words, when the intra prediction mode of the neighboring block 1710 is the vertical prediction mode, the values of each row of the prediction block 1720 may be values of pixels in a horizontal line adjacent to the top of the neighboring block 1710.

Alternatively, when the intra prediction mode of the neighboring block 1710 is the horizontal prediction mode, the value of each column of the prediction block 1720 may be the value of the reference pixels of the neighboring block 1710. In other words, when the intra prediction mode of the neighboring block 1710 is the horizontal prediction mode, values of each column of the prediction block 1720 may be values of pixels in a vertical line adjacent to the left side of the neighboring block 1710.

In addition to the vertical prediction mode and the horizontal prediction mode, a prediction block generation method of an existing image encoding and / or decoding technique such as HEVC and AVC may be used for other intra prediction modes.

In FIG. 30, a current block 1810, a prediction block 1820 of the current block, and a residual signal 1830 of the current block are shown. In FIG. 30, Intra _{current block} _{_ residual signal, which} is the residual signal of the _{current block} , has been described in the form of a matrix equation.

The current block 1810 may correspond to the current block described above with reference to FIGS. 16 and 18. Alternatively, the current block 1810 may correspond to the current block 1610 described above with reference to FIG. 28.

The residual signal 1830 may correspond to the “second residual signal of the current block” described above with reference to FIGS. 16 and 20.

As shown in FIG. 30, the residual signal 1830 may be a difference between the current block 1810 and the prediction block 1820. Alternatively, the residual signal 1830 may be a result of subtracting the prediction block 1820 from the current block 1810.

According to FIG. 30, the sum of the values of the residual signal 1830 is 560. In other words, the level sum of the residual signal 1830 is 560.

The value of the prediction block 1820 may be determined based on the intra prediction mode for the neighboring block 1810.

For example, as shown in FIG. 30, when the intra prediction mode of the current block 1810 is the vertical prediction mode, the value of each row of the prediction block 1820 may be the value of the reference pixels of the neighboring block 1810. . In other words, when the intra prediction mode of the current block 1810 is the vertical prediction mode, the values of each row of the prediction block 1820 may be values of pixels in a horizontal line adjacent to the top of the current block 1810.

Alternatively, when the intra prediction mode of the current block 1810 is the horizontal prediction mode, the value of each column of the prediction block 1820 may be a value of reference pixels of the neighboring block 1810. In other words, when the intra prediction mode of the current block 1810 is the horizontal prediction mode, the values of each column of the prediction block 1820 may be values of pixels in a vertical line adjacent to the left side of the current block 1810.

The method of calculating the residual signal 1830 of the current block 1810 described with reference to FIG. 30 is described in detail with reference to the current block of step 940 described above with reference to FIG. 16 and step 1045 described above with reference to FIG. 20. 2 may correspond to residual signal generation.

In addition, the method of calculating the residual signal 1830 of the current block 1810 described with reference to FIG. 30 may correspond to the generation of the third residual signal of the current block of

steps

940 and 1045.

The residual signal after the residual signal prediction according to embodiments is described in detail with reference to FIG. 31 below.

31 illustrates a residual signal prediction method according to an example.

In FIG. 31, the residual signal 1910 of the current block, the residual signal 1920 of the neighboring block, and the prediction residual signal 1930 of the current block are shown. In FIG. 31, the Intra _{prediction residual signal, which} is the prediction residual signal of the current block, has been described in the form of a matrix equation.

FIG. 31 may illustrate residual signal prediction of step 950 of FIG. 9 and step 1042 of FIG. 10.

The residual signal 1910 of the current block may correspond to the residual signal 1830 of the current block described above with reference to FIG. 30. Alternatively, the residual signal 1910 of the current block may correspond to the “second residual signal of the current block” described above with reference to FIGS. 16 and 20.

The residual signal 1920 of the neighboring block may correspond to the residual signal 1730 of the neighboring block described above with reference to FIG. 29. Alternatively, the residual signal 1920 of the neighboring block may correspond to the "residual signal of the first neighboring block" described above with reference to FIGS. 16 and 20.

The prediction residual signal 1930 of the current block may correspond to the “first residual signal of the current block” described above with reference to FIGS. 16 and 20.

The prediction residual signal 1930 may be a difference between the residual signal 1910 of the current block and the residual signal 1920 of the neighboring block. Alternatively, the prediction residual signal 1930 may be a result of subtracting the residual signal 1920 of the neighboring block from the residual signal 1910 of the current block.

The sum of the values of the prediction residual signal 1930 is 267. In other words, the sum of the levels of the prediction residual signal 1930 is 267. By residual signal prediction, the sum of the levels of the final residual signal of the current block is reduced from 560 to 269. Decreasing the level sum of the final residual signal by the residual signal prediction may indicate that the energy of the residual signal itself used for encoding of the current block is reduced. Reducing the energy of the residual signal itself used for encoding may mean that the amount of bits required for encoding is reduced. Therefore, the encoding apparatus 800 may reduce the capacity of the bitstream through prediction of the residual signal.

32 illustrates a default residual signal according to an example.

The default residual of FIG. 32 may be an example of the second residual signal described above with reference to FIGS. 16 and 20. In other words, the default residual may be the residual signal of the current block before the residual signal prediction. Alternatively, the default residual of FIG. 32 may be an example of the residual signal 1910 of the current block described above with reference to FIG. 31.

In FIG. 33, the results of the discrete cosine transform for the default residual signal of FIG. 32 are shown.

34 illustrates a proposed residual signal according to an example.

The proposed residual of FIG. 34 may be an example of the first residual signal described above with reference to FIGS. 16 and 20. In other words, the proposed residual may be the residual signal of the current block according to the residual signal prediction. Alternatively, the proposed residual of FIG. 32 may be an example of the prediction residual signal 1930 of the current block described above with reference to FIG. 31.

In FIG. 35, the result of the discrete cosine transform for the default residual signal of FIG. 34 is shown.

32 to 35, it can be seen that the energy concentration in the frequency domain is increased by the residual signal prediction. The intra residual predictor 810 may improve energy concentration in the frequency domain of the residual signal of the current block through the residual signal prediction. As the magnitude of the coefficient value in the frequency domain is reduced by the residual signal prediction, the probability that the result value generated by quantization becomes zero and the probability that the result value generated by quantization becomes close to zero may be improved.

36 illustrates a position of a neighboring block according to an example.

In FIG. 28, the peripheral block 1620 is shown adjacent to the left of the current block 1610. In FIG. 28, the case where the residual signal prediction is performed using the left neighboring block has been described. However, the position of the first neighboring block described above with reference to FIGS. 16 and 20 may not be limited to the left side of the current block 1610.

As described above in operation 935 of FIG. 9 and operation 1043 of FIG. 10, the intra residual predictor 810 may determine a first neighboring block among one or more neighboring blocks of the current block. The first neighboring block may be a block used for residual signal prediction. The intra residual predictor 810 may determine a first neighboring block among one or more previously reconstructed neighboring blocks of the current block.

As the first neighboring block is determined among the plurality of neighboring blocks, the intra residual predictor 810 may improve the spatial correlation of the first neighboring block with respect to the residual signal.

In FIG. 36, one or more neighboring blocks of the current block, the lower left neighboring block A ₀ 2221, the left neighboring block A ₁ 2222, the upper right neighboring block B ₁ 2223, the right neighboring block B ₂ 2224 And top left adjacent block B ₃ 2225 is shown. As shown, one or more neighboring blocks of the current block may include a lower left neighboring block, a left neighboring block, a right upper neighboring block, a right neighboring block, and a left upper neighboring block. One or more neighboring blocks of the current block are not limited to blocks in the position illustrated in FIG. 36.

In order to improve the efficiency of the residual signal prediction, the spatial correlation with the current block and neighboring blocks needs to be improved. In order to improve a neighboring block having a high spatial correlation, the intra residual prediction unit 810 may perform residual signal prediction on each neighboring block of the plurality of neighboring blocks of the current block. When a plurality of residual signals for a plurality of neighboring blocks are generated according to the residual signal prediction, the intra residual predictor 810 selects a minimum rate-distortion residual signal having a minimum rate-distortion value among the plurality of residual signals. Can be. Also, the intra residual predictor 810 may select a neighboring block corresponding to the minimum rate-distortion residual signal among the plurality of neighboring blocks. The intra residual predictor 810 may use the neighboring block and the minimum rate-distortion residual signal selected for encoding the current block.

For example, steps 935, 940 and 950 described above with reference to FIG. 16, and

steps

1043, 1044 and 1045 described above with reference to FIG. 20 are currently It may be performed for each block of the plurality of neighboring blocks of the block. Here, the plurality of neighboring blocks of the current block may be at least some of one or more already restored blocks adjacent to the current block. The number of the plurality of neighboring blocks and the positions of the plurality of neighboring blocks may be changed according to the setting of the encoding apparatus 800.

Through repetition of

step

935 or 1043, the intra residual predictor 810 may sequentially select a plurality of neighboring blocks of the current block as the first block.

Through the repetition of operation 950 or operation 1045, the intra residual prediction unit 810 may generate a plurality of first residual signals of a plurality of neighboring blocks of the current block. In addition, the intra residual predictor 810 may calculate a rate-distortion value for each of the plurality of first residual signals.

The intra residual predictor 810 may determine a minimum rate-distortion residual signal having a minimum rate-distortion value among the plurality of first residual signals, and determine a neighboring block corresponding to the minimum rate-distortion residual signal of the current block. The first neighboring block used for the residual signal prediction may be determined.

Step 940 may be repeated together as step 950 is repeated, or may be performed only once. Step 1044 may be repeated together as step 1055 is repeated, or may be performed only once.

In operation 935 and operation 1043, the first neighboring block of the current block may be determined for each coding unit. Also, in steps 985 and 1048, the identifier of the first neighboring block may be encoded for each coding unit.

37 is a structural diagram of a decoding apparatus according to an embodiment.

The decoding device 2300 may correspond to the decoding device 200 described above. The decoding apparatus 200 includes an entropy decoder 210, an inverse quantizer 220, an inverse transformer 230, an intra predictor 240, a motion compensator 250, an adder 255, and a filter 260. And a reference picture buffer 270, and may further include an intra residual predictor 2310.

Entropy decoder 210, inverse quantizer 220, inverse transformer 230, intra predictor 240, motion compensator 250, adder 255, filter 260, and reference picture buffer 270. ) May perform a function and / or operation as described above with reference to FIG. 2. Duplicate explanations are omitted.

In the embodiments described above with reference to FIGS. 16 to 36, the functions and / or operations described as being performed by the intra prediction unit 120 of the encoding apparatus 800 may be performed by the intra prediction unit of the decoding apparatus 2300. 240). In addition, the functions and / or operations described as being performed by the intra residual predictor 810 of the encoding apparatus 800 may be performed by the intra residual predictor 2310 of the decoding apparatus 2300.

In addition, the entropy decoder 210, the inverse quantizer 220, the inverse transformer 230, the intra predictor 240, the motion compensator 250, the adder 255, the filter 260, and the reference picture buffer 270 may perform a function and / or operation related to the intra residual predictor 2310. Entropy decoder 210, inverse quantizer 220, inverse transformer 230, intra predictor 240, motion compensator 250, adder 255, filter 260, reference picture buffer 270 ) And the function and / or operation of the intra residual prediction unit 2310 are described in detail below.

The intra residual predictor 2310 may not be distinguished from the intra predictor 240. The intra predictor 240 and the intra residual predictor 2310 may be integrated into the intra predictor 240, and in embodiments, the functions and / or functions described as being performed by the intra residual predictor 2310 may be performed. The operation may be performed by the intra predictor 240.

Hereinafter, the current block may be a block that is currently the target of decoding, and may be a block in the current image.

First, referring to FIG. 38, step 2410 may be performed.

In operation 2410, the decoding apparatus 2310 may generate a residual signal of the current block. Here, the generated residual signal may correspond to the first residual signal of the current block described above with reference to FIGS. 16 and 20.

Step 2410 may be performed by at least one of the entropy decoder 210, the inverse quantizer 220, and the inverse transformer 230.

Step 2410 may include step 2411, step 2412, and step 2413.

In step 2411, the entropy decoder 210 may generate quantized coefficients for the current block.

In operation 2412, the inverse quantization unit 220 may generate inverse quantized coefficients by performing inverse quantization on the quantized coefficients.

In operation 2413, the inverse transform unit 230 may generate a residual signal by performing an inverse transform on the inverse quantized coefficients.

After step 2410 is performed, step 2420 and step 2 $ 40 may be performed.

Next, reference is made to FIG. 39.

Prior to performing step 2420, a reference sample may be generated. Content related to generation of the reference sample described above with reference to FIG. 22 may also be applied to the present embodiment. Duplicate explanations are omitted.

In operation 2420, the intra predictor 240 may determine whether to update the reference sample.

Here, updating the reference sample may be to reconstruct the sample value of the reference sample used for generation of the prediction block before generating the prediction block of the current block.

The intra predictor 240 may determine whether to perform the update of the reference sample by using information indicating whether to update the reference sample described above with reference to FIGS. 16 and 19. The bitstream transmitted from the encoding apparatus 800 to the decoding apparatus 2300 may include information indicating whether to update the reference sample. Information indicating whether to perform update of the reference sample may be encoded in the bitstream.

The intra predictor 240 may decode information indicating whether to update the encoded reference sample. The intra predictor 240 may determine whether to perform update of the reference sample by using information indicating whether to update the decoded reference sample. If the above information indicates that the reference sample is updated, the intra prediction unit 240 may update the reference sample. If the above information indicates that the reference sample is not updated, the intra prediction unit 240 may not perform the update of the reference sample.

If it is determined to perform an update of the reference sample, step 2425 may be performed. If it is determined not to perform the reference sample update, step 2430 may be performed.

In operation 2425, the intra prediction unit 240 may update the value of the reference sample, and may determine the value of the reference sample used to generate the prediction block of the current block through the update.

The contents related to the update of the reference sample described above with reference to FIGS. 23, 24 and 25 may also be applied to this embodiment. In the embodiments described above with reference to FIGS. 23, 24, and 25, the functions and / or operations described as being performed by the intra prediction unit 120 of the encoding apparatus 800 may be intra prediction of the decoding apparatus 2300. It may be performed by the unit 240. In addition, the functions and / or operations described as performed in step 915 described above with reference to FIG. 16 and step 1022 described above with reference to FIG. 19 may also be performed in step 2425. Duplicate explanations are omitted.

After step 2425 is performed, step 2430 may be performed.

In operation 2430, the intra prediction unit 240 may generate a prediction block of the current block. The intra prediction unit 240 may generate the prediction block of the current block by using the reference sample according to the intra prediction mode for the current block.

After step 2430 is performed, step 2460 or 2490 may be performed.

In operation 2440, the intra residual prediction unit 2310 may determine whether to perform the residual signal prediction.

The intra residual predictor 2310 may determine whether to perform the residual signal prediction using information indicating whether to perform the residual signal prediction described above with reference to FIGS. 16 and 20. The bitstream transmitted from the encoding apparatus 800 to the decoding apparatus 2300 may include information indicating whether residual signal prediction is performed. Information indicating whether the residual signal prediction is performed may be encoded in the bitstream.

The intra predictor 240 may decode information indicating whether to perform encoded residual signal prediction. The intra predictor 240 may determine whether to perform the residual signal prediction using information indicating whether the decoded residual signal prediction is performed. If the above information indicates to perform the residual signal prediction, the intra predictor 240 may perform the residual signal prediction. If the above information indicates that the residual signal prediction is not performed, the intra prediction unit 240 may not perform the residual signal prediction.

If it is determined to perform the residual signal prediction, step 2450 may be performed.

If it is determined not to perform residual signal prediction, step 2490 may be performed.

In operation 2450, the intra residual predictor 2310 may identify the first neighboring block. The first neighboring block may be a block used for residual signal prediction, and may be a block located near the current block. Content related to the determination of the first neighboring block described above with reference to FIG. 36 may also be applied to the present embodiment.

The intra residual predictor 2310 may identify the first neighboring block by using the identifier of the first neighboring block described above with reference to FIGS. 16 and 20. The bitstream transmitted from the encoding apparatus 800 to the decoding apparatus 2300 may include an identifier of the first neighboring block. The identifier of the first neighboring block may be encoded in the bitstream.

The intra residual predictor 2310 may decode the identifier of the encoded first neighboring block. The intra residual predictor 2310 may identify the first neighbor block using the decoded identifier of the first neighbor block.

The position and number of neighboring blocks may be defined according to encoding parameters.

The identifier of the first neighboring block may be configured to indicate the same block in both the encoding apparatus 800 and the decoding apparatus 2300. For example, the size N of the block and the position of the neighboring block may be common to the encoding apparatus 800 and the decoding apparatus 2300 in relation to the identifier of the first neighboring block. In order for the encoding apparatus 800 and the decoding apparatus 2300 to share a common configuration with respect to the identifier of the first neighboring block, the identifier of the first neighboring block is "(neighbor-residual_index) truncated unary ((neighboring) -residual_idx) can be entropy decoded in a " Truncated unary "

Once steps 2450 and 2430 are performed, step 2460 may then be performed.

In operation 2460, the intra residual predictor 2310 may generate a reconstructed block of the current block.

The intra residual predictor 2310 may generate a reconstructed block of the current block based on the prediction block, the residual signal of the current block, and the residual signal of the first neighboring block.

The residual signal of the current block used in operation 2460 may be a residual signal generated by the residual signal prediction in the encoding apparatus 800. In other words, the residual signal of the current block used in operation 2460 may correspond to the first residual signal described above with reference to FIGS. 16 and 20.

The first neighboring block may be a block that has already been restored before decoding of the current block. Therefore, the residual signal of the first neighboring block may also be obtained by the intra residual predictor 2310 before decoding the current block.

The reconstructed block of the current block may be the sum of the prediction block of the current block, the residual signal of the current block, and the residual signal of the neighboring block. In addition, the reconstructed block of the current block may be generated based on the sum of the residual signal of the current block and the residual signal of the first neighboring block.

The reconstruction block may be the sum of 1) the prediction block, 2) the residual signal of the current block, and 3) the residual signal of the first neighboring block. The prediction block may be obtained according to the intra prediction mode. The residual signal of the current block may be transmitted from the encoding apparatus 800 to the decoding apparatus 2300. The residual signal of the first neighboring block may be obtained by residual signal prediction. For example, when the residual signal prediction is not performed, the residual signal of the first neighboring block may be a signal of zero.

In some cases, when the intra residual prediction unit 2310 generates the residual signal of the first neighboring block according to the residual signal prediction, the intra prediction unit 240 may determine the prediction block of the current block, the residual signal of the current block, and the neighboring block. The reconstruction block of the current block may be generated by adding the residual signals.

If step 2430 is performed and it is determined in step 2440 that no residual signal prediction is to be performed, step 2490 may be performed.

In operation 2490, the intra predictor 240 or the intra residual predictor 2310 may generate a reconstructed block of the current block based on the prediction signal and the residual signal of the current block.

The residual signal of the current block used in operation 2490 may be a residual signal generated without performing the residual signal prediction in the encoding apparatus 800. In other words, the residual signal of the current block used in step 2490 may correspond to the third residual signal described above with reference to FIGS. 916 and 20.

First, referring to FIG. 40, step 2510 may be performed.

In operation 2510, the decoding apparatus 2310 may generate a residual signal of the current block. Here, the generated residual signal may correspond to the first residual signal of the current block described above with reference to FIGS. 16 and 20.

Step 2510 may be performed by at least one of the entropy decoder 210, the inverse quantizer 220, and the inverse transformer 230.

Step 2510 may include step 2411, step 2412, and step 2413.

In operation 2511, the entropy decoder 210 may generate quantized coefficients for the current block.

In operation 2512, the inverse quantization unit 220 may generate inverse quantized coefficients by performing inverse quantization on the quantized coefficients.

In operation 2513, the inverse transform unit 230 may generate a residual signal by performing an inverse transform on the inverse quantized coefficients.

After step 2510 is performed, step 2520 to be described below with reference to FIG. 41 may be performed.

In operation 2520, the intra predictor 240 may decode information indicating whether to update the encoded reference sample.

The bitstream transmitted from the encoding apparatus 800 to the decoding apparatus 2300 may include information indicating whether to update the reference sample. Information indicating whether to perform update of the reference sample may be encoded in the bitstream.

In operation 2530, the intra predictor 240 may decode information indicating whether to perform encoded residual signal prediction.

The bitstream transmitted from the encoding apparatus 800 to the decoding apparatus 2300 may include information indicating whether residual signal prediction is performed. Information indicating whether the residual signal prediction is performed may be encoded in the bitstream.

In operation 2540, the intra residual predictor 2310 may decode an identifier of the encoded first neighboring block.

The bitstream transmitted from the encoding apparatus 800 to the decoding apparatus 2300 may include an identifier of the first neighboring block. The identifier of the first neighboring block may be encoded in the bitstream.

In operation 2550, the intra predictor 240 and the intra residual predictor 2310 may decode the residual signal. The intra predictor 240 and the intra residual predictor 2310 may generate a reconstruction block by decoding the residual signal.

Step 2550 may include

steps

2561, 2562, 2563, and 2564 to be described below with reference to FIG. 42.

In addition, step 2550 may include

steps

2551, 2572, 2573, and 2574 to be described below with reference to FIG. 43.

Reference samples may be generated by

steps

2561, 2562 and 2563. Content related to generation of the reference sample described above with reference to FIG. 22 may also be applied to the present embodiment. Duplicate explanations are omitted.

In operation 2561, the intra prediction unit 240 may determine whether to update the reference sample.

The intra predictor 240 may determine whether to perform the update of the reference sample by using information indicating whether to update the reference sample described above with reference to FIGS. 16 and 19.

The intra predictor 240 may determine whether to perform update of the reference sample by using information indicating whether to update the decoded reference sample. If the above information indicates that the reference sample is updated, the intra prediction unit 240 may update the reference sample. If the above information indicates that the reference sample is not updated, the intra prediction unit 240 may not perform the update of the reference sample.

If it is determined to perform an update of the reference sample, step 2503 may be performed. If it is determined not to perform the reference sample update, step 2564 may be performed.

In operation 2403, the intra prediction unit 240 may update the value of the reference sample, and may determine the value of the reference sample used to generate the prediction block of the current block through the update.

The contents related to the update of the reference sample described above with reference to FIGS. 23, 24 and 25 may also be applied to this embodiment. In the embodiments described above with reference to FIGS. 23, 24, and 25, the functions and / or operations described as being performed by the intra prediction unit 120 of the encoding apparatus 800 may be intra prediction of the decoding apparatus 2300. It may be performed by the unit 240. In addition, the functions and / or operations described as being performed in step 915 described above with reference to FIG. 16 and step 1022 described above with reference to FIG. 19 may also be performed in step 2563. Duplicate explanations are omitted.

Step 2564 may be performed after step 2563 is performed.

In operation 2564, the intra prediction unit 240 may generate a prediction block of the current block. The intra prediction unit 240 may generate the prediction block of the current block by using the reference sample according to the intra prediction mode for the current block.

For example, after step 2564 is performed, step 2551 to be described below with reference to FIG. 43 may be performed.

In operation 2257, the intra residual prediction unit 2310 may determine whether to perform the residual signal prediction.

The intra residual predictor 2310 may determine whether to perform the residual signal prediction using information indicating whether to perform the residual signal prediction described above with reference to FIGS. 16 and 20.

The intra predictor 240 may determine whether to perform the residual signal prediction using information indicating whether the decoded residual signal prediction is performed. If the above information indicates to perform the residual signal prediction, the intra predictor 240 may perform the residual signal prediction. If the above information indicates that the residual signal prediction is not performed, the intra prediction unit 240 may not perform the residual signal prediction.

If it is determined to perform the residual signal prediction, step 2252 may be performed.

If it is determined not to perform residual signal prediction, step 2574 may be performed.

In operation 2252, the intra residual predictor 2310 may identify the first neighboring block. The first neighboring block may be a block used for residual signal prediction, and may be a block located near the current block. Content related to the determination of the first neighboring block described above with reference to FIG. 36 may also be applied to the present embodiment.

The intra residual predictor 2310 may identify the first neighboring block by using the identifier of the first neighboring block described above with reference to FIGS. 16 and 20.

The intra residual predictor 2310 may identify the first neighbor block using the decoded identifier of the first neighbor block.

If step 2252 is performed, then step 2573 may be performed.

In operation 2573, the intra residual predictor 2310 may generate a reconstructed block of the current block.

The residual signal of the current block used in operation 2573 may be a residual signal generated by the residual signal prediction in the encoding apparatus 800. In other words, the residual signal of the current block used in step 2573 may correspond to the first residual signal described above with reference to FIGS. 16 and 20.

If it is determined in step 2570 not to perform the residual signal prediction, step 2574 may be performed.

In operation 2574, the intra predictor 240 or the intra residual predictor 2310 may generate a reconstructed block of the current block based on the residual block of the prediction block and the current block.

The residual signal of the current block used in operation 2574 may be a residual signal generated without performing the residual signal prediction in the encoding apparatus 800. In other words, the residual signal of the current block used in step 2574 may correspond to the third residual signal described above with reference to FIGS. 16 and 20.

Residual Implicit transfer of information related to signal prediction

As described above, the bitstream may include 1) information indicating whether to perform residual signal prediction and 2) an identifier of a first neighboring block used for residual signal prediction of the current block. In other words, the information and the identifier may be explicitly transmitted by the encoding apparatus 800 to the decoding apparatus 2300.

On the other hand, when a predetermined condition is met to reduce the amount of bits required for the above information, 1) information indicating whether to perform the residual signal prediction may be omitted. Even if the above information is omitted, the decoding apparatus 2300 may derive the above information when the predetermined condition is satisfied. In other words, the above information may be implicitly transmitted.

In addition, when a predetermined condition is met to reduce the amount of bits required for the above identifier, 2) the identifier of the first neighboring block used for prediction of the residual signal of the current block may be omitted. Even if the above information is omitted, the decoding device 2300 may derive the identifier when the predefined condition is satisfied. In other words, the above identifier can be transmitted explicitly.

In step 930 described above with reference to FIG. 16 and step 1041 described above with reference to FIG. 20, when a predefined condition is satisfied, the intra residual prediction unit 810 performs prediction of the residual signal with respect to the current block. You can decide what to do. Alternatively, when the predefined condition is satisfied, the intra residual predictor 810 may determine not to perform residual signal prediction on the current block.

In addition, in

steps

935 and 1043, when the predefined condition is satisfied, the intra residual prediction unit 810 may determine the predefined block as the first neighboring block. In addition, steps 980, 985, 1048 and 1049 may be optionally performed.

In

operations

980 and 1049, the intra residual prediction unit 810 may selectively encode information indicating whether to perform the residual signal prediction. Alternatively, when the predefined condition is satisfied, the intra residual prediction unit 810 may omit encoding of information indicating whether to perform the residual signal prediction.

In operation 985 and operation 1048, the intra residual prediction unit 810 may selectively encode an identifier of the first neighboring block. Alternatively, when the predefined condition is satisfied, the intra residual predictor 810 may omit encoding of the identifier of the first neighboring block.

In operation 2440 described above with reference to FIG. 39, when a predefined condition is satisfied, the intra residual prediction unit 2310 may determine to perform residual signal prediction. Alternatively, when the predefined condition is satisfied, the intra residual predictor 2310 may determine not to perform the residual signal prediction. For example, if there is no information indicating whether the residual signal is predicted, the intra residual predictor 2310 may determine to perform the residual signal prediction.

In operation 2445, when the predefined condition is satisfied, the intra residual predictor 2310 may identify the selected block as the first neighboring block according to the predefined method. For example, if the identifier of the first neighboring block does not exist, the intra residual predictor 2310 may identify the selected block as the first neighboring block according to a predefined method.

For example, when the direction of the current block and the direction of the first neighboring block are the same, high efficiency may be expected in the residual signal prediction. Therefore, when a block having the same intra prediction mode as the intra prediction mode of the current block exists near the current block, the residual signal prediction of the current block may be performed with respect to the block having the same intra prediction mode.

In step 930 described above with reference to FIG. 16 and step 1041 described above with reference to FIG. 20, if a block having the same intra prediction mode as the intra prediction mode of the current block exists in the vicinity of the current block, the intra The residual predictor 810 may determine to perform residual signal prediction on the current block. For example, if the MPM flag has a value of true (or “1”), the intra residual prediction unit 2310 indicates that a block having the same intra prediction mode as the intra prediction mode of the current block exists near the current block. May be detected, and it may be determined to perform residual signal prediction on the current block. Accordingly, the intra residual predictor 2310 may identify whether the residual signal prediction is used based on the value of the MPM flag.

In addition, in

steps

935 and 1043, when there is a block having the same intra prediction mode as the intra prediction mode of the current block in the vicinity of the current block, the intra residual prediction unit 810 may perform the same intra prediction. The block having the mode may be determined as the first neighboring block. When there are a plurality of blocks having the same intra prediction mode as the intra prediction mode of the current block in the vicinity of the current block, the intra residual prediction unit 810 removes the selected block according to a predefined priority among the plurality of blocks. It can be determined as 1 neighboring block.

In

steps

980 and 1049, when there is a block having the same intra prediction mode as the intra prediction mode of the current block in the vicinity of the current block, the intra residual prediction unit 810 determines whether to perform the residual signal prediction. The encoding of the information indicating may be omitted.

In steps 985 and 1048, when there is a block having the same intra prediction mode as the intra prediction mode of the current block in the vicinity of the current block, the intra residual prediction unit 810 may determine the identifier of the first neighboring block. Coding can be omitted.

In operation 2440 described above with reference to FIG. 39, when a block having the same intra prediction mode as the intra prediction mode of the current block exists near the current block, the intra residual prediction unit 2310 performs the residual signal prediction. You can decide what to do. Alternatively, when there is no information indicating whether the residual signal is predicted, the intra residual predictor 2310 performs residual signal prediction when a block having the same intra prediction mode as the intra prediction mode of the current block exists near the current block. You can decide what to do. Alternatively, when there is no information indicating whether the residual signal is predicted, the intra residual predictor 2310 predicts the residual signal when there is no block having the same intra prediction mode as the intra prediction mode of the current block near the current block. You can decide not to do this.

In operation 2445, when a block having the same intra prediction mode as the intra prediction mode of the current block exists in the vicinity of the current block, the intra residual prediction unit 2310 may select a block having the same intra prediction mode. It may be identified as the first neighboring block. Alternatively, when the identifier of the second block does not exist, the intra residual prediction unit 2310 may determine the same intra prediction mode if the block having the same intra prediction mode as the intra prediction mode of the current block exists near the current block. A block having the first block can be identified. Alternatively, when there is no identifier of the first block and there are a plurality of blocks having the same intra prediction mode as the intra prediction mode of the current block in the vicinity of the current block, the intra residual prediction unit 810 may include the plurality of blocks. The selected block may be determined as the first neighboring block according to the predefined priority.

When intra prediction is performed, the intra prediction mode may be transmitted from the encoding apparatus 800 to the decoding apparatus 2300 through a Most Probable Mode (MPM) flag and an MPM index. In other words, the intra prediction mode may be entropy coded by the MPM flag and the MPM index. The MPM may represent all three intra prediction modes. The intra prediction modes represented by the MPM are named MPM candidate modes. The intra predictor 240 may identify the MPM candidate modes through the prediction block in the screen around the current block.

If the intra prediction mode of the current block is the same as one of the three intra prediction modes identified by the MPM, the value of the MPM flag may be true (or "1"). In addition, when the value of the MPM flag is true (or “1”), the encoding apparatus 800 may transmit the MPM index to the decoding apparatus 2300. The MPM index may indicate which of the MPM candidate modes is the intra prediction mode of the current block.

The intra residual prediction unit 2310 may perform intra prediction according to the definition of the syntax. The intra residual prediction unit 2310 may acquire the residual signal of the current block when the final intra prediction mode obtained after performing the intra prediction is the same as one of the MPM candidate modes, and obtain the residual signal of the first neighboring block. The prediction may be performed on the residual signal of the current block using. If the intra prediction mode of the current block is the same as the intra prediction mode of the first neighboring block, the intra residual prediction unit 2310 may identify a location of the first neighboring block for prediction of the residual signal of the current block through the MPM index. have.

Unit of update of the reference sample.

In operation 2420, the intra predictor 240 may determine whether to update the reference sample for each of the predefined stages. The predefined unit may be at least one of 1) the entire image sequence (ie, video), 2) one image (ie, picture), 3) slice, and 4) coding unit.

For the predefined unit, reference sample update information may be used to indicate whether update of the reference sample is performed. The reference sample update information may be information indicating whether the update of the reference sample has been performed on the predefined unit. For example, the value of the reference sample update information may indicate that the update of the reference sample should be performed in decoding the current block. When the value of the reference sample update information is the second value, it may represent that the update of the reference sample is not performed in decoding the current block.

1) The entire image sequence: Whether to update the reference sample may be determined for the entire image sequence. In this case, the sequence parameter set may include reference sample update information. If the reference sample update information of the sequence parameter set indicates that the update of the reference sample is performed, the intra predictor 240 may perform intra prediction using the reference sample to which the gradient according to the direction is applied to the entire image sequence.

2) One image: Whether to update the reference sample may be determined for each image. In this case, the picture parameter set may include reference sample update information. When the reference sample update information of the picture parameter set indicates that the update of the reference sample is performed, the intra predictor 240 performs intra prediction using the reference sample to which the gradient according to the directionality is applied to the entire image corresponding to the picture parameter set. Can be done.

3) Slice: One image may be divided into a plurality of slice segments or a plurality of tiles in one slice segment. Whether to update the reference sample may be determined for each slice. In this case, the slice segment header may include reference sample update information. If the reference sample update information of the slice segment header indicates that the update of the reference sample is performed, the intra predictor 240 may perform intra prediction using the reference sample to which the gradient according to the direction is applied to the slice corresponding to the slice segment header. Can be.

4) Coding Unit: Whether to perform update of the reference sample may be determined for each coding unit. In such a case, reference sample update information may exist for the coding unit. When the reference sample update information for the coding unit indicates that the coding unit is updated, the intra prediction unit 240 performs intra prediction using the reference sample to which the gradient according to the direction is applied to the coding unit corresponding to the reference sample update information. Can be done.

Residual Unit of signal prediction

In operation 2440, the intra residual prediction unit 2310 may determine whether to perform the residual signal prediction for each predefined unit. The predefined unit may be at least one of 1) the entire image sequence (ie, video), 2) one image (ie, picture), 3) slice, and 4) coding unit.

The residual signal prediction information may be information indicating whether the residual signal prediction has been performed on the predefined unit. For example, the value of the residual signal prediction information being the first value may indicate that the residual signal prediction should be performed in decoding the current block. When the value of the residual signal prediction information is the second value, it may represent that the residual signal prediction is not performed in decoding the current block.

1) Overall Image Sequence: Whether to perform residual signal prediction may be determined for the entire image sequence. In this case, the sequence parameter set may include residual signal prediction information. If the residual signal prediction information of the sequence parameter set indicates that the residual signal prediction is performed, the intra residual prediction unit 2310 may perform the residual signal prediction on the entire image sequence. All blocks encoded by intra prediction in an image sequence may be decoded using residual signal prediction or decoded without using residual signal prediction, depending on whether tram signal prediction is performed.

2) One image: Whether to perform the residual signal prediction may be determined for each image. In this case, the picture parameter set may include residual signal prediction information. When the residual signal prediction information of the picture parameter set indicates that the residual signal prediction is performed, the intra residual prediction unit 2310 may perform residual signal prediction on the entire image corresponding to the picture parameter set. All blocks encoded with intra prediction within one destination may be decoded using residual signal prediction or decoded without using residual signal prediction, depending on whether tram signal prediction is performed.

3) Slice: One image may be divided into a plurality of slice segments or a plurality of tiles in one slice segment. Whether to perform the residual signal prediction may be determined for each slice. In this case, the slice segment header may include residual signal prediction information. If the residual signal prediction information of the slice segment header indicates that the residual signal prediction is performed, the intra residual prediction unit 2310 may perform the residual signal prediction on the slice corresponding to the slice segment header. When the slice segment header includes residual signal prediction information, all blocks encoded with intra prediction at the slice level are decoded using residual signal prediction or not using residual signal prediction, depending on whether tram signal prediction is performed. Can be decrypted.

4) Coding Unit: Whether to perform residual signal prediction may be determined for each coding unit. In this case, residual signal prediction information may exist for the coding unit. If the residual signal prediction information for the coding unit indicates that the coding unit is updated, the intra residual prediction unit 2310 may perform the residual signal prediction on the coding unit corresponding to the residual signal prediction information.

According to an embodiment, the motion predictor 111, the motion compensator 112, the intra predictor 120, the switch 115, the subtractor 125, the transformer 130, and the quantization of the encoding apparatus 800 may be used. The unit 140, the entropy encoding unit 150, the inverse quantization unit 160, the inverse transform unit 170, the adder 175, the filter unit 180, the reference picture buffer 190, and the intra residual prediction unit 810. At least some of the may be program modules and may communicate with an external device or system. The program modules may be included in the encoding apparatus 800 in the form of an operating system, an application module, and other program modules.

The program modules may be physically stored on various known storage devices. In addition, at least some of these program modules may be stored in a remote storage device that can communicate with the encoding device 800.

Program modules perform routines or subroutines, programs, objects, components, and data to perform functions or operations, or to implement abstract data types, according to one embodiment. Data structures and the like, but is not limited thereto.

The program modules may be composed of instructions or codes performed by at least one processor of the encoding apparatus 800.

The encoding device 800 may be implemented as the electronic device 2600 illustrated in FIG. 44. The electronic device 2600 may be a general-purpose computer system that operates as the encoding device 800.

As illustrated in FIG. 44, the electronic device 2600 may include at least one processor 2621, a memory 2623, and a user interface (UI) input device that communicate with each other through a bus 2622. 2626, UI output device 2627, and storage 2628. In addition, the electronic device 2600 may further include a network interface 2629 connected to the network 2630. The processor 2621 may be a semiconductor device that executes processing instructions stored in a central processing unit (CPU), a memory 2623, or a storage 2628. Memory 2623 and storage 2628 may be various forms of volatile or nonvolatile storage media. For example, the memory may include at least one of a ROM 2624 and a RAM 2625.

The encoding apparatus 800 may be implemented in a computer system including a recording medium that may be read by a computer.

The recording medium may store at least one module required for the electronic device 2600 to operate as the encoding device 800. The memory 2623 may store at least one module and may be configured to be executed by the at least one processor 2621.

Functions related to communication of data or information of the encoding apparatus 800 may be performed through the network interface 2629.

According to an embodiment, the entropy decoder 210, the inverse quantizer 220, the inverse transformer 230, the intra predictor 240, the motion compensator 250, and the adder 255 of the decoder 2300. At least some of the filter unit 260, the reference picture buffer 270, and the intra residual predictor 2310 may be program modules, and may communicate with an external device or system. The program modules may be included in the decryption apparatus 2300 in the form of an operating system, an application program module, and other program modules.

The program modules may be physically stored on various known storage devices. In addition, at least some of these program modules may be stored in a remote storage device that can communicate with the decryption apparatus 2300.

The program modules may be composed of instructions or codes performed by at least one processor of the decoding apparatus 2300.

The decoding device 2300 may be implemented as the electronic device 2700 illustrated in FIG. 45. The electronic device 2700 may be a general-purpose computer system that operates as the decoding device 2300.

As illustrated in FIG. 45, the electronic device 2700 may include at least one processor 2721, a memory 2723, and a user interface (UI) input device that communicate with each other through a bus 2722. 2726, a UI output device 2727, and a repository 2728. In addition, the electronic device 2700 may further include a network interface 2729 that is connected to the network 2730. The processor 2721 may be a semiconductor device that executes processing instructions stored in a central processing unit (CPU), a memory 2723, or a storage 2728. Memory 2723 and storage 2728 may be various forms of volatile or nonvolatile storage media. For example, the memory may include at least one of a ROM 2724 and a RAM 2725.

The decryption apparatus 2300 may be implemented in a computer system including a recording medium that may be read by a computer.

The recording medium may store at least one module required for the electronic device 2700 to operate as the decoding device 2300. The memory 2723 may store at least one module and may be configured to be executed by the at least one processor 2721.

Functions related to communication of data or information of the decoding apparatus 2300 may be performed through the network interface 2729.

In the above-described embodiments, the methods are described based on a flowchart as a series of steps or units, but the present invention is not limited to the order of steps, and certain steps may occur in a different order or simultaneously from other steps as described above. Can be. Also, one of ordinary skill in the art appreciates that the steps shown in the flowcharts are not exclusive, that other steps may be included, or that one or more steps in the flowcharts may be deleted without affecting the scope of the present invention. I can understand.

Embodiments according to the present invention described above may be implemented in the form of program instructions that may be executed by various computer components, and may be recorded in a computer-readable recording medium. The computer-readable recording medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the computer-readable recording medium may be those specially designed and configured for the present invention, or may be known and available to those skilled in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CD-ROMs, DVDs, and magneto-optical media such as floptical disks. media), and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the process according to the invention, and vice versa.

Although the present invention has been described by specific embodiments such as specific components and the like, but the embodiments and the drawings are provided to assist in a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations can be made from these descriptions.

Accordingly, the spirit of the present invention should not be limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the appended claims, fall within the scope of the spirit of the present invention. I will say.

Claims

In the video encoding method,

Generating a first residual signal of the current block based on the residual signal of the first neighboring block of the current block; And

Performing encoding of the current block using the first residual signal of the current block

Image encoding method comprising a.
The method of claim 1,

Generating a second residual signal of the current block

More,

The second residual signal is a difference between the current block and a prediction block of the current block,

And the first residual signal is generated based on the second residual signal and the residual signal of the neighboring block.
The method of claim 2,

And the first residual signal is generated based on a difference between the second residual signal and a residual signal of the first neighboring block.
The method of claim 2,

And the first residual signal is a difference between the second residual signal and the residual signal of the first neighboring block.
The method of claim 1,

Determining whether to perform residual signal prediction

More,

The generating may be performed when the residual signal prediction is determined to be performed.
The method of claim 3,

Encoding information indicating whether to perform the residual signal prediction

Image encoding method further comprising.
The method of claim 1,

Encoding an identifier of the first neighboring block

Image encoding method further comprising.
In the video decoding method,

Generating a prediction block of the current block; And

Generating a reconstructed block of the current block based on the prediction block, the residual signal of the current block, and the residual signal of a first neighboring block of the current block;

Decoding method of an image comprising a.
The method of claim 8,

And the reconstruction block is generated based on the sum of the residual signal of the current block and the residual signal of the first neighboring block.
The method of claim 8,

The reconstructed block is a sum of a prediction block of the current block, a residual signal of the current block, and a residual signal of the first neighboring block.
The method of claim 8,

Generating a residual signal of the current block

Decoding method of the image further comprising.
The method of claim 8,

Identifying the first neighboring block

More,

And the first neighboring block is identified by an identifier of the first neighboring block.
The method of claim 12,

And if the identifier of the first neighboring block does not exist, the selected block is identified as the first neighboring block according to a predefined method.
The method of claim 8,

Updating a value of a reference sample used to generate the prediction block

Decryption method further comprising.
In the video decoding method,

Determining a value of a reference sample based on a neighboring block of the current block; And

Generating a predictive block of the current block using the reference sample

Decoding method of an image comprising a.
The method of claim 15,

A method of decoding an image, wherein a value of the reference sample is determined based on an inclination pattern of the neighboring block;
The method of claim 15,

And a value of the reference sample is determined based on a slope value between two adjacent reference samples among a plurality of reference samples belonging to one row of the neighboring block.
The method of claim 15,

In the determining step, the value of the reference sample is changed from the value before the update to the value after the update,

And a value before the update is a value generated as a block including the reference sample is predicted and reconstructed.
The method of claim 15,

When the intra prediction mode for the current block is a horizontal prediction mode, the reference sample is a sample adjacent to the left side of the current block, and the neighboring block is a top neighboring block of the current block and a top left neighboring block of the current block. A method of decoding an image that is a sum block.
In the video encoding method,

Determining a value of a reference sample based on a neighboring block of the current block; And

Generating a predictive block of the current block using the reference sample

Image encoding method comprising a.