KR20120129726A - Methods of decoding intra prediction mode and decoder - Google Patents

Abstract

PURPOSE: An intra prediction mode encoding/decoding method and an apparatus thereof are provided to generate a prediction block by receiving intra prediction information based on flag information. CONSTITUTION: In case there is identity indication flag information, a decoding unit determines existence of identity location indication flag information(S1500,S1510). In case there is identity location flag information, the decoding unit generates a prediction block of a current prediction unit(S1520). In case there is not identity location flag information, the decoding unit generates a prediction block(S1530). [Reference numerals] (AA) Start; (BB) End; (S1500) Determining existence of identity location indication flag information; (S1510) Determining existence of identity location indication flag; (S1520) Generating expectation blocks based on identity location indication flag information; (S1530) Generating a prediction block based on identity indication flag information; (S1540) Generating a prediction block using similar first intra block flag information expectation mode difference information

Description

Intra prediction mode decoding method and decoding apparatus {METHODS OF DECODING INTRA PREDICTION MODE AND DECODER}

The present invention relates to an intra prediction mode decoding method and a decoding apparatus, and more particularly, to a decoding method and apparatus.

Recently, the demand for high resolution and high quality images such as high definition (HD) image and ultra high definition (UHD) image is increasing in various applications. As the video data becomes higher resolution and higher quality, the amount of data increases relative to the existing video data. Therefore, when the video data is transmitted or stored using a medium such as a conventional wired / wireless broadband line, The storage cost will increase. High-efficiency image compression techniques can be utilized to solve such problems as image data becomes high-resolution and high-quality.

An inter picture prediction technique for predicting a pixel value included in a current picture from a previous or a subsequent picture of a current picture using an image compression technique, an intra picture prediction technique for predicting a pixel value included in a current picture using pixel information in the current picture, There are various techniques such as an entropy encoding technique in which a short code is assigned to a value having a high appearance frequency and a long code is assigned to a value having a low appearance frequency. Image data can be effectively compressed and transmitted or stored using such an image compression technique.

A first object of the present invention is to provide an intra prediction mode decoding method for increasing image coding efficiency.

It is also a second object of the present invention to provide an apparatus for performing an intra prediction mode decoding method to increase image encoding efficiency.

An intra prediction mode decoding method according to an aspect of the present invention for achieving the first object of the present invention described above provides intra prediction information of the current prediction unit from the neighboring prediction unit of the current prediction unit based on predetermined flag information. And receiving the prediction block of the current prediction unit based on the receiving and the intra prediction information of the current prediction unit. The predetermined flag information includes identity indication flag information indicating whether a first intra prediction mode of the current prediction unit and a second intra prediction mode of the current block provided from the neighboring prediction unit are the same, and the first intra prediction mode. May be the same position indication flag information indicating whether a first intra prediction mode provided from any neighboring prediction unit of the neighboring prediction units is the same as a second intra prediction mode of the current prediction unit. The predetermined flag information may include the second intra prediction mode of the first intra prediction mode when the first intra prediction mode of the current prediction unit and the second intra prediction mode of the current prediction unit are not the same. Similar first intra prediction mode information serving as a reference for calculating the difference information with and intra prediction mode difference information indicating a difference between the similar first intra prediction mode and the second intra prediction mode. The intra prediction mode difference information is assigned to the intra prediction mode having the largest angle in the clockwise direction with respect to the vertical intra prediction mode, the smallest value in the constant integer range, and the largest in the counterclockwise direction with respect to the horizontal intra prediction mode. The second intra prediction mode value may be subtracted from the reallocated first intra prediction mode value by allocating the largest value in the constant integer range to the intra prediction mode having an angle. The intra prediction mode difference information is assigned to the intra prediction mode having the largest angle in the counterclockwise direction with respect to the horizontal intra prediction mode, and assigns the smallest value in the constant integer range and the largest angle in the clockwise direction with respect to the vertical intra prediction mode. It may be a value obtained by subtracting the reassigned second intra prediction mode value from the reassigned first intra prediction mode value by allocating the largest value in a predetermined integer range to the intra prediction mode having. The neighboring prediction unit may be at least one prediction unit among at least one prediction unit among the top neighbor prediction units positioned at the top of the current prediction unit and at least one prediction unit among the left neighbor prediction units located to the left of the current prediction unit. The neighboring prediction unit may include at least one prediction unit among a prediction unit existing at the same position as the current prediction unit existing in the previous frame of the frame including the current prediction unit and a neighboring prediction unit located at the top right of the current prediction unit. It may further include. The neighboring prediction unit may be a prediction unit located at the top of the left neighboring prediction unit of the current prediction unit and a top neighboring prediction unit of the current prediction unit. The neighboring prediction unit is the prediction unit located at the bottom of the left neighboring prediction unit of the current prediction unit and the rightmost prediction unit located at the top of the top neighboring prediction unit of the current prediction unit, or the largest left neighboring prediction unit of the current prediction unit. It may be the largest prediction unit of the prediction unit and the top peripheral prediction unit of the current prediction unit. The neighboring prediction unit is characterized in that predicted in the intra prediction mode, when the neighboring prediction unit is not available when the intra prediction mode of the unavailable neighboring prediction unit in the DC mode, or at least one neighboring prediction unit is available The same mode as the intra prediction mode of the at least one neighboring prediction unit available may be used as the intra prediction mode of the unavailable neighboring prediction unit. The current prediction unit may be further divided into a plurality of prediction units.

In addition, the decoder according to an aspect of the present invention for achieving the above-described second object of the present invention decodes the predetermined flag information to provide the intra prediction information of the current prediction unit and the current provided by the entropy decoder The intra prediction unit may be configured to generate the prediction block of the current prediction unit based on the intra prediction information of the prediction unit. The predetermined flag information includes identity indication flag information indicating whether a first intra prediction mode of the current prediction unit and a second intra prediction mode of the current block provided from the neighboring prediction unit are the same, and the first intra prediction mode. May be the same position indication flag information indicating whether a first intra prediction mode provided from any neighboring prediction unit of the neighboring prediction units is the same as a second intra prediction mode of the current prediction unit. The predetermined flag information may include the second intra prediction mode of the first intra prediction mode when the first intra prediction mode of the current prediction unit and the second intra prediction mode of the current prediction unit are not the same. Similar first intra prediction mode information serving as a reference for calculating the difference information with and intra prediction mode difference information indicating a difference between the similar first intra prediction mode and the second intra prediction mode. The intra prediction mode difference information is assigned to the intra prediction mode having the largest angle in the clockwise direction with respect to the vertical intra prediction mode, the smallest value in the constant integer range, and the largest in the counterclockwise direction with respect to the horizontal intra prediction mode. The second intra prediction mode value may be subtracted from the reallocated first intra prediction mode value by allocating the largest value in the constant integer range to the intra prediction mode having an angle. The intra prediction mode difference information is assigned to the intra prediction mode having the largest angle in the counterclockwise direction with respect to the horizontal intra prediction mode, and assigns the smallest value in the constant integer range and the largest angle in the clockwise direction with respect to the vertical intra prediction mode. It may be a value obtained by subtracting the reassigned second intra prediction mode value from the reassigned first intra prediction mode value by allocating the largest value in a predetermined integer range to the intra prediction mode having. The neighboring prediction unit may be at least one prediction unit among at least one prediction unit among the top neighbor prediction units positioned at the top of the current prediction unit and at least one prediction unit among the left neighbor prediction units located to the left of the current prediction unit. The neighboring prediction unit may include at least one prediction unit among a prediction unit existing at the same position as the current prediction unit existing in the previous frame of the frame including the current prediction unit and a neighboring prediction unit located at the top right of the current prediction unit. It may further include. The neighboring prediction unit is a prediction unit located at the top of the left neighboring prediction unit of the current prediction unit and a prediction unit located at the leftmost of the top neighboring prediction unit of the current prediction unit, or at the bottom of the left neighboring prediction unit of the current prediction unit. The rightmost prediction unit located among the prediction units located and the top neighbor prediction unit of the current prediction unit, or the largest prediction unit among the largest prediction unit among the left prediction units of the current prediction unit and the top neighbor prediction unit of the current prediction unit. Can be. The current prediction unit may be further divided into a plurality of prediction units.

As described above, according to the intra prediction mode decoding method and decoding apparatus according to an embodiment of the present invention, the current prediction unit is received by receiving intra prediction information of the current prediction unit from the neighboring prediction unit of the current prediction unit based on the predetermined flag information. Generate a predictive block of. Therefore, the intra prediction mode of the current prediction unit can be encoded with a small number of bits, thereby improving the coding efficiency.

1 is a block diagram illustrating an encoding apparatus according to an embodiment of the present invention.
2 is a block diagram schematically illustrating a configuration of an intra prediction unit according to an embodiment of the present invention.
3 is a block diagram of a decoding apparatus according to an embodiment of the present invention.
4 is a conceptual diagram illustrating an intra prediction mode according to an embodiment of the present invention.
5 is a conceptual diagram illustrating a method of encoding an intra prediction mode of a current block according to an embodiment of the present invention.
6 is a conceptual diagram illustrating an intra prediction mode encoding method according to an embodiment of the present invention.
7 is a conceptual diagram illustrating a case where a current block is located at a boundary of a slice in the intra prediction mode encoding method according to an embodiment of the present invention.
8 is a conceptual diagram illustrating a case where a current block is located at a slice boundary in an intra prediction mode encoding method according to an embodiment of the present invention.
9 is a conceptual diagram illustrating a case where a size of a neighboring block and a current block of a current block is different according to an embodiment of the present invention.
10 is a conceptual diagram illustrating a case where a size of a neighboring block of a current block is larger than a size of a current block according to an embodiment of the present invention.
11 is a conceptual diagram illustrating an intra prediction mode encoding method according to an embodiment of the present invention.
12 is a conceptual diagram illustrating an intra prediction mode encoding method according to an embodiment of the present invention.
13 is a conceptual diagram illustrating a method of calculating an intra prediction mode according to an embodiment of the present invention.
14 is a conceptual diagram illustrating an intra prediction mode encoding method according to another embodiment of the present invention.
15 is a flowchart illustrating a method of decoding an intra prediction mode according to another embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

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

Referring to FIG. 1, the video encoding apparatus includes a picture splitter 110, an inter predictor 120, an intra predictor 125, a transformer 130, a quantizer 135, and an inverse quantizer 140. , An inverse transform unit 145, a deblocking filter 150, a memory 160, a reordering unit 165, and an entropy encoding unit 170.

The current picture is input to the picture division unit 110 and can be divided into one or more coding units. The coding unit refers to one unit in which encoding is performed in the video encoding apparatus and may also be referred to as a coding unit (CU). The encoding unit can be hierarchically divided with depth information based on a quad tree structure. The largest coding unit is the largest coding unit (LCU), and the smallest coding unit is the smallest coding unit (SCU). The encoding unit may have a size of 8x8, 16x16, 32x32, and 64x64. The picture division unit 110 may divide the encoding unit and generate a prediction unit and a conversion unit. The prediction unit may be referred to as a PU (Prediction Unit), and the conversion unit may be referred to as a TU (Transform Unit).

In the inter prediction mode, the inter prediction unit 120 may perform motion estimation (ME) and motion compensation (MC). The inter prediction unit 120 generates a prediction block based on at least one picture information of a previous picture or a subsequent picture of the current picture, which may also be referred to as inter prediction.

The inter prediction unit 120 is provided with the divided prediction target block and at least one reference block stored in the memory unit 160. The inter predictor 120 performs motion estimation using the prediction target block and the reference block. The inter prediction unit 120 generates motion information including a motion vector (MV), a reference block index, a prediction mode, and the like as a result of the motion estimation.

In addition, the inter prediction unit 120 performs motion compensation using the motion information and the reference block. In this case, the inter prediction unit 120 generates and outputs a prediction block corresponding to the input block from the reference block.

The motion information is entropy coded to form a compressed bit stream and is transmitted from the video encoding apparatus to the video decoding apparatus.

In the intra prediction mode, the intra predictor 125 may generate a prediction block based on pixel information in the current picture. Intra prediction may be referred to as in-picture prediction. In the intra prediction mode, the intra prediction unit 125 receives a prediction target block and a reconstructed block previously encoded, decoded and reconstructed. However, the inputted reconstruction block is an image before passing through the deblocking filter unit. The reconstruction block may be a previous prediction block.

2 is a block diagram schematically illustrating a configuration of an intra prediction unit according to an embodiment of the present invention.

Referring to FIG. 2, the intra predictor includes a reference pixel generator 210, an intra prediction mode determiner 220, and a predictive block generator 230.

The reference pixel generator 210 generates a reference pixel for intra prediction. Pixels on the rightmost vertical line of the left block adjacent to the prediction target block and pixels on the bottom horizontal line of the upper block adjacent to the prediction block are used for generating the reference pixel. For example, if the size of the prediction target block is N, 2N pixels are used as reference pixels in respective left and top directions. The reference pixel may be used as it is, or may be used after being filtered through an adaptive intra smoothing filter (AIS). In case of AIS filtering, information related to AIS filtering is signaled.

The intra prediction mode determiner 220 receives the prediction target block and the reconstruction block. The intra prediction mode determination unit 220 selects a mode that minimizes the amount of information to be encoded in the prediction mode using the input image, and outputs the prediction mode information. At this time, a predetermined cost function or a Hadamard transform can be used.

The intra prediction mode determiner may predict and encode an intra mode of the current block based on intra prediction mode information of neighboring blocks of the current block.

Hereinafter, in the embodiment of the present invention, the neighboring block is a block spatially adjacent to the current block and refers to a block located on the left side of the current block and a block located on the top of the current block, and the current block predicted based on the intra prediction mode of the neighboring block. The intra prediction mode of is defined as a term of a first intra prediction mode, and the actual intra prediction mode of a current block calculated by a predetermined formula or function, such as a cost function, is defined as a term of a second intra prediction mode.

In the intra prediction mode encoding method according to an embodiment of the present invention, binary flag information (hereinafter referred to as identity indication flag information) indicating whether or not the same as the first intra prediction mode that is the intra prediction mode of the neighboring block of the current block is used. When the first intra prediction mode has a plurality of values of the second intra prediction mode information of the current block, whether the second intra prediction mode of the current block is the same as the intra prediction mode of the left neighboring block among the values of the first intra prediction mode. Alternatively, whether the same as the intra prediction mode of the upper neighboring block may be displayed using additional binary flag information (hereinafter, referred to as the same block indication flag information).

If the first intra prediction mode has a plurality of values, whether the second intra prediction mode of the current block is the same as the intra prediction mode of the left neighboring block among the values of the first intra prediction mode, or the intra prediction of the upper neighboring block. Whether it is the same as the mode can be displayed using additional binary flag information (hereinafter, the same position block display flag information).

The following various methods may be used to calculate the first intra prediction mode.

If there is a block smaller than the size of the current block as a neighboring block of the current block, the first intra prediction mode is performed in the topmost block among the left neighboring blocks of the current block and the leftmost block among the top neighboring blocks of the current block. By calculating, it may be determined whether it is the same as the second intra prediction mode of the current intra block (hereinafter, referred to as a basic candidate block setting method). Hereinafter, in the embodiment of the present invention, the neighboring block for calculating the first intra prediction mode is called a first intra prediction mode candidate block.

In a particular case, the first intra prediction mode candidate block may set the first intra prediction mode candidate block by setting a block located at the bottom of the left neighboring blocks of the current block and the rightmost block in the top neighboring block of the current block as the first intra prediction mode candidate block. It may be determined whether the intra prediction mode of the prediction mode candidate block is the same as the second intra prediction mode of the current block (hereinafter, referred to as a first candidate block setting method). When the block located at the lower left and the upper right is used as the first intra prediction mode candidate block, separate information indicating that the block at the lower left and upper right is used as the first intra prediction mode candidate block (hereinafter, reconfigured the first candidate block). Flag) may be additionally transmitted to use a block located at the lower left and the upper right as the first intra prediction mode candidate block.

Further, in a particular case, taking the right side of FIG. 9 as an example, the second intra of the current intra block is set by setting the largest block among the left neighboring blocks of the current block and the largest block among the upper neighboring blocks of the current block to the first intra prediction mode. It may be determined whether the prediction mode is the same (hereinafter, referred to as a second candidate block setting method).

The intra prediction mode of the three neighboring blocks located around the current block and the intra prediction mode of the colocated block existing at the same position as the current block located in the previous frame of the frame in which the current block is located are selected as the first intra prediction mode candidate block. Can be used as

In other words, intra prediction of the left neighboring block, the upper neighboring block, the upper right neighboring block, which are spatial neighboring blocks located near the current block, and the temporal neighboring block existing at the same position as the current block existing in the previous frame of the current block. The mode may be a first intra prediction mode.

The prediction mode generator 230 receives the prediction mode information and the reference pixel. The prediction block generator 230 generates prediction blocks by spatially predicting and compensating pixel values of the prediction target block by using prediction mode information and reference pixel values.

The prediction mode information is entropy coded to form a compressed bit stream together with image data and the like, and is transmitted from the video encoding apparatus to the video decoding apparatus. The video decoding apparatus uses the prediction mode information when generating an intra prediction block.

Referring back to FIG. 1, a difference block is generated by a difference between a prediction target block and a prediction block generated in an inter or intra prediction mode, which is input to the transform unit 130. The transformer 130 performs transform on the difference block in a transform unit (TU) to generate transform coefficients.

The transform block having the transform unit has a quad tree structure within the maximum and minimum sizes, and thus is not dependent on a predetermined size. Each transform block has a flag indicating whether the current block is divided into sub-blocks. If the indicator has a value of 1, the current transform block can be divided into four sub-blocks of the same size. have. Discrete Cosine Transform (DCT) can be used for the transformation.

The quantizer 135 may quantize the values converted by the transformer 130. The quantization coefficient may change depending on the block or the importance of the image. The quantized transform coefficient values may be provided to the reordering unit 165 and the inverse quantization unit 140.

The reordering unit 165 may change the quantized two-dimensional block transform coefficients into a one-dimensional vector transform coefficient through a scan in order to increase the efficiency of entropy encoding. The reordering unit 165 can increase the entropy encoding efficiency by varying the scan order based on the probabilistic statistics.

The entropy encoding unit 170 entropy-encodes the values obtained by the reordering unit 165, and the encoded information forms a compressed bitstream and is transmitted or stored via a network abstraction layer (NAL).

The inverse quantization unit 140 receives a transform coefficient quantized by the quantization unit 135 to perform inverse quantization, which is inversely transformed by the inverse transform unit 145 to generate a reconstructed difference block. The reconstructed differential block may be combined with the prediction block generated by the inter predictor 120 or the intra predictor 125 to generate a reconstructed block. The reconstruction block is provided to the intra predictor 125 and the deblocking filter 150.

The deblocking filter 150 filters the reconstructed block to remove distortion between block boundaries occurring in the encoding and decoding process, and the filtered result is provided to an adaptive loop filter (ALF) 155.

The ALF 155 performs filtering to minimize the error between the predicted block and the last reconstructed block. The ALF 155 performs filtering based on a value obtained by comparing the reconstructed block filtered through the deblocking filter 150 with the current prediction target block, and the filter coefficient information of the ALF 155 is a slice header. Is transmitted from the encoding apparatus to the decoding apparatus.

The memory 160 may store a final reconstructed block obtained through the ALF 155, and the stored final reconstructed block may be provided to the inter predictor 120 that performs inter prediction.

3 is a block diagram of a decoding apparatus according to an embodiment of the present invention.

Referring to FIG. 3, the video decoding apparatus includes an entropy decoder 310, a reordering unit 315, an inverse quantizer 320, an inverse transformer 325, an inter predictor 330, and an intra predictor 335. , Deblocking filter 340, ALF 345, and memory 350.

The entropy decoding unit 310 receives the compressed bitstream from the NAL. The entropy decoding unit 310 entropy-decodes the received bitstream, and entropy decodes together the prediction mode and motion vector information included in the bitstream. The entropy-decoded transform coefficient or difference signal is provided to the reordering unit 315. [ The reordering unit 315 inverse scans the inverse scan to generate transform coefficients in the form of a two-dimensional block.

In addition, the entropy decoding unit 310 decodes information for performing intra prediction, such as identity flag information, co-location flag information, pseudo first intra flag information, intra prediction mode difference information, and transmits the information to the intra prediction unit 335. Can be provided to

The entropy-decoded and re-transformed transform coefficients are input to the inverse quantization unit 320 and the inverse quantization unit 320 dequantizes the transform coefficients. The inverse transformer 325 inverse transforms the inverse quantized transform coefficients to generate a difference block.

The difference block may be combined with the prediction block generated by the inter predictor 330 or the intra predictor 335 to generate a reconstructed block. The reconstruction block is provided to the intra predictor 335 and the deblocking filter 340. The operations of the inter predictor 330 and the intra predictor 335 may be the same as the operations of the inter predictor 120 and the intra predictor 125 in the video encoding apparatus, respectively.

The intra predictor 335 may generate a prediction block based on the information provided by the encoder. When the identity indication flag information is present based on the information decoded by the entropy decoder 310, it is determined that the second intra prediction mode of the current block is the same as at least one of the first intra prediction modes that are intra prediction modes of the neighboring block. In this case, it is possible to determine from which neighboring block the intra prediction mode is to be taken. When the identity indication flag information is present, when there are a plurality of first intra prediction mode candidate blocks of the current block according to the same position indication flag information, based on the intra prediction mode information included in a predetermined one of the first intra prediction mode candidate blocks. A prediction block of the current block can be generated. If the same position indication flag information does not exist, it means that there is only one first intra prediction mode candidate block of the current block, and the prediction block of the current block is determined based on the intra prediction mode information of the first intra prediction mode candidate block. Can be generated. If the identity indication flag information does not exist, intra prediction mode information of the first intra prediction mode candidate block is calculated based on the similar first intra block flag information, and the first intra prediction calculated using the intra prediction mode difference information. The prediction block of the current block may be generated by receiving information on how different the prediction mode of the mode candidate block is.

The deblocking filter 340 filters the reconstructed block to remove distortion between block boundaries occurring in the encoding and decoding process, and the filtered result is provided to an adaptive loop filter (ALF) 345. The ALF 345 performs filtering to minimize the error between the predicted block and the last reconstructed block. The memory 160 may store a final reconstructed block obtained through the ALF 345, and the stored final reconstructed block may be provided to the inter predictor 330 that performs inter prediction.

4 is a conceptual diagram illustrating an intra prediction mode according to an embodiment of the present invention.

Referring to FIG. 4, the current prediction unit may have an intra prediction mode from 1 to 33 as an intra prediction mode. The number of intra prediction modes for generating the prediction block may vary depending on the size of the prediction unit. That is, the type of intra prediction mode used may vary according to the size of the prediction unit.

Hereinafter, the term flag information used in the embodiment of the present invention is a value used for displaying predetermined information during encoding and decoding. In the following embodiment of the present invention, a binary value is assumed, but it is different from the nature of the present invention. Unless a binary number is used, it can be represented using a means other than binary.

In addition, when the left peripheral prediction unit used in the embodiment of the present invention is referred to as the point located on the leftmost top of the current prediction unit, it refers to a prediction unit including a point of position, and the upper peripheral prediction unit indicates a point of position. The upper left prediction unit refers to a prediction unit that includes the prediction unit, and refers to a prediction unit including a point of position when referring to the size of the axial prediction unit.

5 is a conceptual diagram illustrating a method of encoding an intra prediction mode of a current prediction unit according to an embodiment of the present invention.

Hereinafter, in the intra prediction mode encoding method, the intra prediction mode of the current prediction unit 500 may be predicted based on the intra prediction modes of the neighboring prediction units 510 and 520 of the current prediction unit 500. Can be.

Hereinafter, in an embodiment of the present invention, the neighboring prediction unit is a prediction unit spatially adjacent to the current prediction unit and refers to a prediction unit located on the left side of the current prediction unit and a prediction unit located on the top of the current prediction unit, and includes the neighboring prediction units 510 and 520. The intra prediction mode of the current prediction unit 500 predicted based on the intra prediction mode of is defined as a term of the first intra prediction mode, and is calculated by a predetermined formula or function, such as a cost function, of the current prediction unit 500. The actual intra prediction mode is defined and used in terms of the second intra prediction mode.

Referring to FIG. 5, the first intra prediction mode of the current prediction unit 500 may be calculated based on the intra prediction modes of the neighboring prediction units 510 and 520 of the current prediction unit 500.

In the intra prediction mode encoding method according to an embodiment of the present invention, the intra prediction mode of at least one neighboring prediction unit among the intra prediction modes of the neighboring prediction units 510 and 520 may be the second intra prediction mode of the current prediction unit 500. The second intra prediction mode information of the current prediction unit 500 may be encoded by using information related to whether or not the same. Since the current prediction unit 500 is likely to be the same as the intra prediction mode of the neighboring prediction units 510 and 520, the intra prediction mode of the current prediction unit 500 and the intra prediction mode of the neighboring prediction units 510 and 520 If the same, the binary flag information indicating whether the intra prediction mode of the current prediction unit 500 is the same as the first intra prediction mode that is the intra prediction mode of the neighboring prediction units 510 and 520 of the current prediction unit (hereinafter, the identity indication) The second intra prediction mode information of the current prediction unit 500 may be encoded using the flag information. For example, when the intra prediction mode of the current prediction unit 500 is the same as at least one of the intra prediction modes of the neighboring prediction units 510 and 520, the value of the identity indication flag information is set to 1, and the current prediction unit When the intra prediction mode of 500 is not the same as at least one of the intra prediction modes of the neighboring prediction units 510 and 520, the intra prediction mode may be encoded by setting the value of the identity display flag information to 0 and encoding the identity display flag information. By transmitting to the decoder, the decoder can know the intra prediction mode information of the current prediction unit. For example, when the received identity indication flag information is 1, the intra prediction mode information of the current prediction unit 500 for generating the prediction block is taken from the neighboring prediction units 510 and 520 of the current prediction unit 500. Can come.

When the intra prediction modes of the left peripheral prediction unit 510 and the upper peripheral prediction unit 520 are the same, the first intra prediction mode is one value, but the left peripheral prediction unit 510 and the upper peripheral prediction unit 520 are the same. When the intra prediction modes are different, the intra prediction mode of the left peripheral prediction unit 510 and the intra prediction mode of the upper peripheral prediction unit 520 become the first intra prediction mode, and the first intra prediction mode may have a plurality of values. Can be. If the first intra prediction mode has a plurality of values, the second intra prediction mode of the current prediction unit is the same as the intra prediction mode of the left peripheral prediction unit 510 among the values of the first intra prediction mode, or the top peripheral prediction Whether it is the same as the intra prediction mode of the unit 520 may be displayed using additional binary flag information (hereinafter, the same location block indication flag information).

For example, if the first intra prediction mode of the upper peripheral prediction unit 520 of the current prediction unit 500 and the second intra prediction mode of the current prediction unit 500 are the same, the same position indication flag information of 0 is used. By expressing that the intra prediction mode of the upper peripheral prediction unit 520 of the current prediction unit 500 and the second intra prediction mode of the current prediction unit 500 is the same, the left peripheral prediction unit of the current prediction unit 500 If it is the same as the intra prediction mode of 510 and the second intra prediction mode of the current prediction unit 500, the intra of the upper peripheral prediction unit 520 of the current prediction unit 500 is used by using the same position indication flag information of 1. It may be expressed that the prediction mode and the second intra prediction mode of the current prediction unit 500 are the same.

The decoding unit generates intra prediction mode information of neighboring prediction units 510 and 520 of the current prediction unit 500 when generating a prediction block for the current prediction unit 500 by using the same indication flag information and the same position indication flag information. Whether there is a neighboring prediction unit 520 and an intra prediction mode in which the current prediction unit 500 and the intra prediction mode are the same, or if the intra prediction mode is the same as the upper peripheral prediction unit 520 or the intra prediction mode. Is equal to and may generate a prediction block for the current prediction unit 500.

If the second intra prediction mode of the current prediction unit 500 and the first intra prediction mode are not the same and at least one first intra prediction mode exists, the second intra prediction mode of the current prediction unit 500 is closer to the second intra prediction mode. The intra prediction mode information of the current prediction unit 500 is obtained by using difference information between the first intra prediction mode (hereinafter, referred to as a similar first intra prediction mode) and the second intra prediction mode based on the similar first intra prediction mode. Can be encoded.

Table 1 below shows a rearrangement intra prediction mode 1 by 1 in an anti-clockwise direction using intra prediction mode 6, which is an intra prediction mode located on the upper right side, in the intra prediction mode of 33 directions described above with reference to FIG. 3. The rearrangement intra prediction mode is obtained by increasing the number of intra prediction modes to the intra prediction mode 9 located in the lower left direction in a way of increasing. Hereinafter, in the embodiment of the present invention, Table 1 is referred to as a rearranged intra prediction mode table.

The difference value information between the pseudo first intra prediction mode and the second intra prediction mode may be generated and encoded through the rearranged intra prediction mode table.

6 is a conceptual diagram illustrating an intra prediction mode encoding method according to an embodiment of the present invention.

Referring to the left side of FIG. 6, the intra prediction mode of the left peripheral prediction unit 610 is 0, the intra prediction mode of the upper peripheral prediction unit 620 is 0, and the intra prediction mode of the current prediction unit 600 is You can assume 23. In this case, since the first intra prediction mode is 0 and the second intra prediction mode is 23, the second intra prediction mode information of the current prediction unit 600 is determined using the indication flag information and the same position indication flag information. Can not express. Therefore, in the intra prediction mode encoding method according to an embodiment of the present invention, the difference information between the first intra prediction mode and the second intra prediction mode (hereinafter, referred to as the first intra prediction mode and the second intra prediction mode) using Table 1 is used. The intra prediction mode of the current prediction unit 600 may be encoded by using the difference information as the intra prediction mode difference information.

Referring to Table 1, since intra prediction mode 0 is mapped to 8 and intra prediction mode 23 is mapped to 5, the difference between the first intra prediction mode mapping value 8 and the second intra prediction mode mapping value 5 is In operation 3, intra prediction mode information of the current prediction unit 600 may be generated. That is, the intra prediction mode of the current prediction unit 600 may be encoded through intra prediction mode difference information, which is a value obtained by subtracting the second intra prediction mode from the first intra prediction mode.

6, the intra prediction mode of the upper peripheral prediction unit 650 of the current prediction unit 630 is 0, the intra prediction mode of the left peripheral prediction unit 640 is 5, and the current prediction unit 600 is shown. This indicates the case where the intra prediction mode of is 23.

Since there are a plurality of first intra prediction modes of the current prediction unit 600, a first intra prediction mode that is relatively close to the second intra prediction mode of the current prediction unit 600 among the plurality of first intra prediction modes is similar to a first intra. The prediction mode may be left and the second intra prediction mode of the current prediction unit 600 may be encoded. Since the intra prediction mode 5 of the first intra prediction mode is located at a smaller angle than the intra prediction mode 23 which is the second intra prediction mode of the current prediction unit 600 than the intra prediction mode 0, the intra prediction mode 5 is selected. Based on which direction, the second intra prediction mode of the current prediction unit 600 may be calculated based on Table 1 (intra prediction mode 0 is 8 and intra prediction mode 5 is 4 and 23 intra prediction). Mode is mapped to 5).

Since intra prediction mode 5 is adjacent to intra 23 prediction mode, the intra prediction mode of the left neighboring prediction unit is used as a reference intra prediction mode for encoding the second intra prediction mode information of the current prediction unit with predetermined flag information. Information (hereinafter, referred to as pseudo first intra prediction mode information) may be encoded, and information about which difference in which direction the second intra prediction mode of the current prediction unit has in the pseudo first intra prediction mode may be transmitted. Since the value obtained by subtracting the 23 intra prediction mode from the 5 intra prediction mode, which is the reference intra prediction mode, becomes −1, the second intra prediction mode of the current prediction unit may be encoded using this value as intra prediction mode difference information.

The decoder may know the intra prediction mode of the current block by using the pseudo first intra prediction mode information and the intra prediction mode difference information transmitted from the encoder, and generate the prediction block.

In the intra prediction mode encoding method according to an embodiment of the present invention, as shown in Table 2 below, in contrast to the rearrangement order of Table 1, 0 is mapped to intra prediction mode 9, which is an intra prediction mode located at the lower left, and clockwise. If the first intra prediction mode and the second intra prediction mode are not the same as the method described above with reference to FIG. 6 by increasing the prediction mode number by one up to the sixth intra prediction mode, the second intra prediction mode of the current prediction unit is changed. Can transmit

In the above-described intra prediction mode encoding method according to the embodiment of the present invention, it is assumed that all of the prediction units exist around the current prediction unit, but when the current prediction unit is located at the boundary of the slice, at least one of the neighboring prediction units is available. You can't.

7 is a conceptual diagram illustrating a case where a current prediction unit is located at a boundary of a slice in the intra prediction mode encoding method according to an embodiment of the present invention.

Referring to FIG. 7, the left side 700 of FIG. 7 illustrates a case in which the current prediction unit is located at the top of the slice so that no neighboring top prediction unit exists. In the middle 710 of FIG. It is located on the left side and indicates that there is no left neighboring prediction unit. The right side 720 of FIG. 7 illustrates a case in which the current prediction unit is located at the upper left side of the slice, so that neither the top neighboring prediction unit nor the left neighboring prediction unit exists.

If the current prediction unit is located at the top of the slice and there is no upper neighboring block, the intra prediction mode of the nonexistent upper block may be assumed to be a DC mode among the intra prediction modes, and the first intra prediction mode of the current block may be calculated. have. Even if the current prediction unit is located on the left side of the slice and the upper neighboring prediction unit does not exist, the intra prediction mode of the left neighboring prediction unit that does not exist equally is assumed to be a DC mode among the intra prediction modes, and the first intra of the current prediction unit is present. The prediction mode can be calculated. In addition, when the current prediction unit is located at the upper left of the slice so that the upper neighboring prediction unit and the left neighboring prediction unit are not located, the intra prediction modes of the upper neighboring prediction unit and the left neighboring prediction unit are both assumed to be DC modes. The first intra prediction mode of may be calculated. In the intra prediction mode encoding method according to an embodiment of the present invention, in the case of the intra prediction mode in which the current prediction unit is located at the slice boundary and does not exist as in the above-described method, the DC prediction mode may be assumed. If any one exists, the intra prediction mode of the current prediction unit may be generated using the intra prediction mode of the available neighboring prediction unit.

Similarly, even when the neighboring block of the current prediction unit is not available, the decoder may also assume the DC mode and generate the first intra prediction mode of the current prediction unit.

8 is a conceptual diagram illustrating a case where a current prediction unit is located at a slice boundary in an intra prediction mode encoding method according to an embodiment of the present invention.

Referring to FIG. 8, the left side 800 of FIG. 8 indicates when the current prediction unit is located at the top of the slice and there is no top peripheral prediction unit. In this case, the intra prediction mode of the top peripheral prediction unit that does not exist is present. A first intra prediction mode may be generated assuming an intra prediction mode of a left neighboring prediction unit of the prediction unit. In addition, the right 810 of FIG. 8 may include a current prediction unit located on the left side of the slice, If not present, the first intra prediction mode may be generated by assuming that the intra prediction mode of the left prediction unit that does not exist is the intra prediction mode of the upper peripheral prediction unit.

In the decoder, similarly to the encoder, when the neighboring prediction unit of one of the neighboring prediction units of the current prediction unit is not available, the intra prediction mode of the neighboring prediction unit that does not use the first intra prediction mode of another neighboring prediction unit is available. Can be assumed and used.

In the intra prediction mode encoding method described above with reference to FIGS. 5 to 8, it is assumed that the size of the neighboring prediction unit of the current prediction unit is the same as the size of the current prediction unit. However, since the size of the prediction mode is different, the neighbor prediction of the current prediction unit is different. There are many cases where the size of the unit is not the same as the size of the current prediction unit.

9 is a conceptual diagram illustrating a case where a neighboring prediction unit of a current prediction unit and a size of the current prediction unit are different according to an embodiment of the present invention.

Referring to FIG. 9, a prediction unit smaller than the size of the current prediction unit may exist as a neighboring prediction unit of the current prediction units 900 and 950. In this case, the first intra prediction mode is performed in the prediction units 910 and 960 located at the top of the left neighboring prediction units of the current prediction unit, and the prediction units 920 and 970 located in the leftmost of the top peripheral prediction units of the current prediction unit. It may be determined whether or not it is the same as the second intra prediction mode of the current intra block (hereinafter, referred to as a basic candidate block setting method). Hereinafter, in the embodiment of the present invention, the neighboring prediction unit for calculating the first intra prediction mode is called a first intra prediction mode candidate block.

In a particular case, the first intra prediction mode candidate block may include a prediction unit 915, 965 located at the bottom of the left neighboring prediction units of the current prediction unit, and a prediction unit 925 located at the right of the top peripheral prediction units of the current prediction unit. 975 may be set as a first intra prediction mode candidate prediction unit to determine whether an intra prediction mode of the first intra prediction mode candidate prediction unit is the same as a second intra prediction mode of the current prediction unit (hereinafter, referred to as a first intra prediction mode candidate prediction unit). How to set up candidate blocks). When the prediction unit located at the lower left and the upper right is used as the first intra prediction mode candidate block, separate information that the prediction unit located at the lower left and upper right is used as the first intra prediction mode candidate block (hereinafter, referred to as a first candidate block). The reset flag) may be additionally transmitted to use the prediction unit located at the lower left and the upper right as the first intra prediction mode candidate block.

Also, in a specific case, taking the right side of FIG. 9 as an example, the largest intra prediction unit 960 among the left neighboring prediction units of the current prediction unit and the largest prediction unit 980 among the upper neighboring prediction units of the current prediction unit are defined as the first intra. By setting the prediction mode, it may be determined whether it is the same as the second intra prediction mode of the current prediction unit (hereinafter, referred to as a second candidate block setting method). When there are a plurality of prediction units having the largest size, one of the plurality of prediction units may be selected using a basic candidate block setting method or a first candidate block setting method. When the largest prediction unit among the prediction units located at the lower left and the upper right is used as the first intra prediction mode candidate block, additional information (hereinafter, referred to as a second candidate block reset flag) is additionally transmitted to transmit the additional information. A prediction unit having the largest size among the prediction units may be used as the first intra prediction mode candidate block.

10 is a conceptual diagram illustrating a case where the size of the neighboring prediction unit of the current prediction unit is larger than the size of the current prediction unit, according to an embodiment of the present invention.

The largest prediction unit among the neighboring prediction units of the current prediction unit may be determined as the neighboring block for calculating the first intra prediction mode of the current prediction unit.

Referring to the left side of FIG. 10, the neighboring prediction units 1010 and 1020, which are the largest prediction units among the neighboring prediction units of the current prediction unit 1000, are used to calculate the first intra prediction mode of the current prediction unit 1000. In the middle of FIG. 10, the neighboring prediction unit 1040. 1050, which is the largest prediction unit among the neighboring prediction units of the current prediction unit 1030, calculates the first intra prediction mode of the current prediction unit. 10 is determined as a neighbor prediction unit, and when the two prediction units 1070 and 1080 of the current prediction unit 1060 exist in different sizes at the top, they have a relatively larger size. The neighboring prediction unit 1080 may be determined as the neighboring prediction unit for calculating the first intra prediction mode of the current prediction unit.

The above-described intra prediction mode encoding method may be similarly applied to the decoder to generate a prediction block of the current prediction unit. The encoder may transmit the generated first candidate block reset flag and the second candidate block reset flag information to the decoder, and the decoder may use the first candidate block reset flag and the second candidate block reset flag information to transmit the current prediction unit. Information about which neighboring prediction unit was used to generate the predictive block may be transmitted.

11 is a conceptual diagram illustrating an intra prediction mode encoding method according to an embodiment of the present invention.

Referring to FIG. 11, when there is a prediction unit encoded in the inter prediction mode instead of the intra prediction mode around the current prediction unit, the inter prediction mode when the intra prediction mode encoding method described above with reference to FIGS. 5 to 10 is used. A first intra prediction mode of the current prediction unit may be calculated except for the prediction unit encoded by.

For example, as described above with reference to FIG. 9, the prediction unit located at the top of the left neighboring prediction units of the current prediction unit and the prediction unit located at the left of the top peripheral prediction unit of the current prediction unit are set to the first intra prediction mode. If it is determined whether or not the same as the second intra prediction mode of the current prediction unit, if the prediction unit B 1100 and the prediction unit C 1110 is encoded in the inter prediction mode as shown in the left side of FIG. The prediction unit D 1120 may be used instead of the prediction unit C 1110 as a neighbor prediction unit for predicting the prediction unit.

When the upper right and lower left prediction units are used as peripheral prediction units for calculating the first intra prediction mode of the current prediction unit (that is, when using the first candidate setting method) and located on the left and top of the current prediction unit The same is true when the prediction unit having the largest size among the prediction units is used as the first intra prediction mode candidate block for generating the prediction prediction unit of the current prediction unit (that is, when the second candidate setting method is used). The prediction unit generated by being predicted by the inter prediction method rather than the intra prediction in the vicinity is excluded from the neighbor prediction unit for calculating the first intra prediction mode of the current prediction unit, and then uses the remaining prediction units to predict the first intra prediction of the current prediction unit. A first intra prediction mode candidate block for calculating a mode may be generated.

12 is a conceptual diagram illustrating an intra prediction mode encoding method according to an embodiment of the present invention.

Referring to FIG. 12, a short distance intra prediction (SDIP) method may be used to generate a prediction block of a current prediction unit. The SDIP method is a method of predicting a plurality of divided prediction units one by one by dividing one prediction unit into a plurality of prediction units.

In the case of using the SDIP method, as described above, in order to calculate the first intra prediction mode of the current prediction unit, the prediction unit located at the top of the left neighboring prediction unit of the current prediction unit and the top neighboring prediction unit of the current prediction unit Basic candidate block setting method that utilizes intra prediction mode information of the prediction unit located on the left side, the prediction unit located at the bottom of the left neighboring prediction units of the current prediction unit, and the rightmost prediction unit located at the top peripheral prediction unit of the current prediction unit. A method for setting a first candidate block, which is a method of using a prediction unit as a first intra prediction mode, and determines the largest prediction unit among the neighboring prediction units of the current prediction unit as the neighboring prediction unit for calculating the first intra prediction mode of the current block. A second candidate block setting method may be used.

12 illustrates a case in which a prediction unit having the same size as the current prediction unit exists as a neighboring prediction unit of the current prediction unit, and a middle portion of FIG. 11 is a prediction unit having a size smaller than the current prediction unit as a neighboring prediction unit of the current prediction unit. 11 illustrates a case in which the neighboring prediction unit of the current prediction unit exists as a prediction unit having various sizes.

When the first intra prediction mode information of the current prediction unit is encoded by using the basic candidate block setting method to calculate the first intra prediction mode of the current prediction unit, a current having a neighboring prediction unit having the form shown in the left side of FIG. In the prediction unit, the prediction unit may encode intra prediction mode information by using the prediction unit A and the prediction unit B as the first intra prediction mode candidate block, and the prediction unit is the prediction unit and the prediction unit B, and the prediction unit is the prediction unit and the prediction unit. Intra prediction mode information may be encoded using B as a first intra prediction mode candidate prediction unit.

Similarly, the current prediction unit having the neighboring prediction unit in the form of the middle of FIG. 12 and the right side of FIG. 12 is similarly based on the intra prediction mode of the prediction unit located at the top left of the current prediction unit and the prediction unit located at the top left of the current prediction unit. Intra prediction mode information of the current prediction unit may be encoded.

The first candidate block setting method may also be used to generate the first intra prediction mode candidate block of the current prediction unit in the same manner as described above. For example, in the case of a current prediction unit having a neighboring prediction unit of the form shown in the middle of FIG. 12, the prediction unit B and the prediction unit C may be used to calculate the first intra prediction mode of the prediction unit. The prediction unit and the prediction unit C may be used to calculate the first intra prediction mode, and the prediction unit and the prediction unit D may be used to calculate the first intra prediction mode of the prediction unit.

The current prediction unit illustrated in the left side of FIG. 12 and the right side of FIG. 12 may also calculate the first intra prediction mode of the current prediction unit in the same manner.

The second candidate block setting method is the same as described above, but since the current prediction unit is a prediction unit predicted using the SDIP method, the first intra prediction mode information of the current prediction unit may be encoded in consideration of this.

For example, in the case of the right side of FIG. 12, the prediction unit may calculate a first intra prediction mode based on the prediction unit A and the prediction unit D, and the prediction unit is the first intra based on the prediction unit and the prediction unit E. The prediction mode may be calculated, and the prediction unit may calculate the first intra prediction mode based on the prediction unit and the prediction unit E.

13 is a conceptual diagram illustrating a method of calculating an intra prediction mode according to an embodiment of the present invention.

Referring to FIG. 13, when there is an inter prediction, that is, an inter predicted prediction unit, as the neighboring prediction unit of the current prediction unit, the above-described basic candidate mode targeting only the intra predicted prediction unit except the inter predicted prediction unit The candidate block for calculating the prediction mode of the current prediction unit may be generated using the setting method, the first candidate mode setting method, and the second candidate mode setting method. Taking the right side of FIG. 13 as an example, assuming that the basic candidate setting method is used, the DC mode may be used because the prediction unit B and the prediction unit D are not available to calculate the first intra prediction mode of the prediction unit. The prediction unit and the prediction unit E may be used to calculate the first intra prediction mode of the prediction unit, and the prediction unit and the prediction unit F may be used to calculate the first intra prediction mode of the prediction unit.

14 is a conceptual diagram illustrating an intra prediction mode encoding method according to another embodiment of the present invention.

Referring to FIG. 14, an intra prediction mode of three prediction units located around a current prediction unit and an intra of a prediction unit co-located with a current prediction unit located in a previous frame of a frame in which the current prediction unit is located. The prediction mode may be used as the first intra prediction mode candidate block.

That is, the left neighbor prediction unit 1410, the top neighbor prediction unit 1420, the top right neighbor prediction unit 1430, which are spatial neighboring blocks located in the periphery of the current prediction unit 1400, and exist in the previous frame of the current prediction unit The intra prediction mode of the temporal neighboring prediction unit 1450 present at the same position as that of the current prediction unit may be set as the first intra prediction mode. As described above, it is determined whether the first intra prediction mode and the second intra prediction mode of the current prediction unit are the same, and when at least one of the first intra prediction modes is the same as the second intra prediction mode, the identity indication flag information and Whether to use intra prediction mode information of the neighboring prediction unit of the current prediction unit when generating a prediction block for the current prediction unit by using the co-location flag information, and if there is a neighboring prediction unit having the same prediction prediction unit and the intra prediction mode. The information for generating the prediction block for the current prediction unit may be encoded by indicating whether the upper neighbor prediction unit and the intra prediction mode are the same or whether the left neighbor prediction unit and the intra prediction mode are the same. For example, as shown in FIG. 14, the same position indication flag is 1 in the top peripheral prediction unit 1420 of the current prediction unit among spatial neighboring prediction units 1410, 1420, and 1430, 0 in the left prediction unit 1410, and top. Encoding and decoding information on whether the second intra prediction mode of the current prediction unit is the same as the first intra prediction mode of which peripheral prediction unit is set by setting 10 to the right prediction unit 1430 and 11 to the temporal neighbor prediction unit 1450. Can be transmitted to the device. The temporal neighbor prediction unit 1450 may be used to generate a prediction block of the current prediction unit as an additional candidate block in the method described above with reference to FIGS. 5 to 13.

In addition, as described above, when the same intra prediction mode as the second intra prediction mode does not exist among the first intra prediction modes, intra prediction of the current prediction unit using pseudo first intra prediction mode information and intra prediction mode difference information. The mode can be known and a prediction block can be generated.

In FIG. 14, the identity indication flag information, the same position indication flag information, the similar first intra block flag information, and the intra prediction mode difference information for generating the prediction block of the current prediction unit described above may be transmitted to the decoder, and the decoder In FIG. 4, decoding may be performed based on transmitted identicality indication flag information, identical position indication flag information, pseudo first intra prediction mode information, and intra prediction mode difference information.

In FIG. 14, the upper peripheral prediction unit, the left peripheral prediction unit, the upper right prediction unit, and the temporal peripheral prediction unit of the current prediction unit are all used as the spatial neighbor prediction unit, but among them, the upper peripheral prediction unit is excluded. Only the prediction unit, the left neighboring prediction unit, and the temporal neighboring prediction unit may be used as the prediction unit for predicting the intra prediction mode of the current prediction unit.

15 is a flowchart illustrating a method of decoding an intra prediction mode according to another embodiment of the present invention.

The intra prediction mode information of the current prediction unit encoded based on the above-described intra prediction mode encoding method may be transmitted to the decoder, and the first intra prediction mode candidate block of the current prediction unit is determined through the same determination process as the encoder. In addition, intra prediction mode information may be provided in the first intra prediction mode candidate block.

Referring to FIG. 15, it is determined whether the identity indication flag information exists (step S1500).

When the identity indication flag information is present, it indicates that the second intra prediction mode of the current prediction unit is the same as at least one of the first intra prediction modes that are the intra prediction modes of the neighboring prediction unit, and thus the decoder indicates that the identity indication flag information is the same. It may be determined whether there is an intra prediction mode for generating the prediction block of the current prediction unit from the neighboring prediction unit.

If the sameness indication flag information exists, it is determined whether the same position indication flag information exists (step S1510).

When the same indication flag information is present, it is determined whether the same position indication flag information is present, and when there are a plurality of first intra prediction mode candidate blocks of the current prediction unit, any first intra prediction mode candidate among the first intra prediction mode candidate blocks is present. It may be determined whether the intra prediction mode information of the block is used to generate the prediction block of the current prediction unit.

If the same position indication flag information exists, a prediction block of the current prediction unit is generated based on the same position indication flag information (step S1520).

When the co-location flag information is present, whether a plurality of first intra prediction mode candidate blocks of the current prediction unit are to use intra prediction mode information of which first intra prediction mode candidate block among the first intra prediction mode candidate blocks is used. In this case, the prediction block of the current prediction unit may be generated based on the intra prediction mode information of the neighboring prediction unit of the current prediction unit indicated by the same position indication flag information.

If the same position indication flag information does not exist, a prediction block of the current prediction unit is generated based on the same indication flag information (step S1530).

If the co-location flag information does not exist, it means that there is only one first intra prediction mode candidate block of the current prediction unit and predicts the current prediction unit based on the intra prediction mode information of the first intra prediction mode candidate block. You can create a block.

If the sameness indication flag information does not exist, the prediction block of the current prediction unit is generated using the similar first intra block flag information and the intra prediction mode difference information (step S1540).

If the identity indication flag information does not exist, as described above with reference to FIG. 5, the intra prediction mode of the current prediction unit may be expressed using the difference in the directionality of the current prediction unit and the first intra prediction mode candidate block, and the information is similar. The first intra block flag information and the intra prediction mode difference information are generated and transmitted to the decoder. The decoder calculates the intra prediction mode information of the first intra prediction mode candidate block based on the similar first intra block flag information, and in the prediction mode of the first intra prediction mode candidate block calculated using the intra prediction mode difference information. It is possible to generate a prediction block of the current prediction unit by being provided with information on how different the difference is.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims (23)

Receiving intra prediction information of the current prediction unit from a neighboring prediction unit of the current prediction unit based on predetermined flag information; And
And generating a prediction block of the current prediction unit based on intra prediction information of the current prediction unit. The method of claim 1, wherein the predetermined flag information,
Identity indication flag information indicating whether a first intra prediction mode of the current prediction unit and a second intra prediction mode of the current block provided from the neighboring prediction unit are the same; And
Co-located flag information indicating whether a first intra prediction mode provided from any neighboring prediction unit among the neighboring prediction units is the same as a second intra prediction mode of the current prediction unit when the plurality of first intra prediction modes exist. Intra prediction mode decoding method characterized in that. The method of claim 1, wherein the predetermined flag information,
When the first intra prediction mode of the current prediction unit and the second intra prediction mode of the current prediction unit provided from the neighboring prediction unit are not the same, difference information between the second intra prediction mode of the first intra prediction mode is calculated. Pseudo first intra prediction mode information serving as a reference for performing the same; And
And intra prediction mode difference information indicating a difference between the pseudo first intra prediction mode and the second intra prediction mode. The method of claim 3, wherein the intra prediction mode difference information,
Assigns the smallest value in a range of constants to the intra prediction mode with the largest angle clockwise relative to the vertical intra prediction mode, and to the intra prediction mode with the largest angle counterclockwise relative to the horizontal intra prediction mode. And reassigning the second intra prediction mode value from the reassigned first intra prediction mode value by allocating the largest value in the constant integer range. The method of claim 3, wherein the intra prediction mode difference information,
Assign the smallest value in the constant integer range to the intra prediction mode with the largest angle counterclockwise relative to the horizontal intra prediction mode and the intra prediction mode with the largest angle clockwise relative to the vertical intra prediction mode. And a second sub prediction mode value reallocated from the first intra prediction mode value reassigned by allocating the largest value in the integer range. The method of claim 1, wherein the neighboring prediction unit,
At least one prediction unit of the top peripheral prediction units located at the top of the current prediction unit; And
And at least one prediction unit among the left neighboring prediction units located to the left of the current prediction unit. The method of claim 6, wherein the neighboring prediction unit,
Intra prediction further comprising at least one prediction unit among a prediction unit existing at the same position as the current prediction unit existing in the previous frame of the frame including the current prediction unit and a neighboring prediction unit located on the upper right side of the current prediction unit Mode Decoding Method. The method of claim 1, wherein the neighboring prediction unit,
And a prediction unit located at the top of the left neighboring prediction units of the current prediction unit and a prediction unit located at the top of the current prediction unit. The method of claim 1, wherein the neighboring prediction unit,
And a prediction unit located at the bottom of the left neighboring prediction units of the current prediction unit and a prediction unit located at the rightmost of the top peripheral prediction units of the current prediction unit. The method of claim 1, wherein the neighboring prediction unit,
And the largest prediction unit among the largest neighboring prediction unit among the left neighboring prediction units of the current prediction unit and the upper neighboring prediction unit of the current prediction unit. The method of claim 1, wherein the neighboring prediction unit,
Characterized in that it is predicted by the intra prediction mode and when the neighboring prediction unit is not available, the intra prediction mode of the unavailable neighboring prediction unit is the DC mode, or when at least one neighboring prediction unit is available, the available at least The same method as the intra prediction mode of one neighboring prediction unit is used as the intra prediction mode of the unavailable neighboring prediction unit. The method of claim 1, wherein the current prediction unit,
Intra prediction mode decoding method characterized in that it is further divided into a plurality of prediction units. An entropy decoder configured to decode predetermined flag information and provide intra prediction information of a current prediction unit; And
And an intra prediction unit configured to generate a prediction block of the current prediction unit based on intra prediction information of the current prediction unit provided by the entropy decoder. The method of claim 13, wherein the predetermined flag information,
Identity indication flag information indicating whether a first intra prediction mode of the current prediction unit and a second intra prediction mode of the current block provided from the neighboring prediction unit are the same; And
Co-located flag information indicating whether a first intra prediction mode provided from any neighboring prediction unit among the neighboring prediction units is the same as a second intra prediction mode of the current prediction unit when the plurality of first intra prediction modes exist. And a decoder. The method of claim 13, wherein the predetermined flag information,
When the first intra prediction mode of the current prediction unit and the second intra prediction mode of the current prediction unit provided from the neighboring prediction unit are not the same, difference information between the second intra prediction mode of the first intra prediction mode is calculated. Pseudo first intra prediction mode information serving as a reference for performing the same; And
And intra prediction mode difference information indicating a difference between the pseudo first intra prediction mode and the second intra prediction mode. The method of claim 15, wherein the intra prediction mode difference information,
Assigns the smallest value in a range of constants to the intra prediction mode with the largest angle clockwise relative to the vertical intra prediction mode, and to the intra prediction mode with the largest angle counterclockwise relative to the horizontal intra prediction mode. And a subtracted second intra prediction mode value from a reallocated first intra prediction mode value by allocating a largest value in the constant integer range. The method of claim 15, wherein the intra prediction mode difference information,
Assign the smallest value in the constant integer range to the intra prediction mode with the largest angle counterclockwise relative to the horizontal intra prediction mode and the intra prediction mode with the largest angle clockwise relative to the vertical intra prediction mode. And a subtracted second intra prediction mode value from a reallocated first intra prediction mode value by allocating the largest value in the integer range. The method of claim 13, wherein the neighboring prediction unit,
At least one prediction unit of the top peripheral prediction units located at the top of the current prediction unit; And
And at least one prediction unit among the left neighboring prediction units located to the left of the current prediction unit. The method of claim 13, wherein the neighboring prediction unit,
A decoder further comprising at least one prediction unit among a prediction unit existing at the same position as the current prediction unit existing in the previous frame of the frame including the current prediction unit and a neighboring prediction unit located on the upper right side of the current prediction unit. . The method of claim 13, wherein the neighboring prediction unit,
And a prediction unit located at the top of the left neighboring prediction units of the current prediction unit and a prediction unit located at the left of the top peripheral prediction units of the current prediction unit. The method of claim 13, wherein the neighboring prediction unit,
And a prediction unit located at the bottom of the left neighboring prediction units of the current prediction unit and a prediction unit located at the rightmost of the top peripheral prediction units of the current prediction unit. The method of claim 13, wherein the neighboring prediction unit,
And a largest prediction unit among the left neighboring prediction units of the current prediction unit and a largest prediction unit among the top neighboring prediction units of the current prediction unit. The method of claim 13, wherein the current prediction unit,
Decoder further divided into a plurality of prediction units.

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