WO2017175897A1

WO2017175897A1 - Method and apparatus for encoding/decoding video signal by using intra-residual prediction

Info

Publication number: WO2017175897A1
Application number: PCT/KR2016/003667
Authority: WO
Inventors: 유선미; 허진; 남정학
Original assignee: 엘지전자(주)
Priority date: 2016-04-07
Filing date: 2016-04-07
Publication date: 2017-10-12

Abstract

The present invention provides a method for decoding a video signal, the method comprising the steps of: discovering a reference block related to a current block, wherein the reference block has already been reconstructed in a current frame; generating a reference prediction signal representing a predictive value of the discovered reference block; generating a reference residual signal by subtracting the reference prediction signal from the reference block; compensating a residual signal of the current block acquired from the video signal on the basis of the reference residual signal; and reconstructing the current block by adding the compensated residual signal and a prediction signal of the current block.

Description

Method and apparatus for encoding and decoding video signals using intra residual prediction

The present invention relates to a method and apparatus for encoding / decoding a video signal, and more particularly, to a technique for processing a video signal using intra residual prediction.

Compression coding refers to a series of signal processing techniques for transmitting digitized information through a communication line or for storing in a form suitable for a storage medium. Media such as an image, an image, an audio, and the like may be a target of compression encoding. In particular, a technique of performing compression encoding on an image is called video image compression.

Next-generation video content will be characterized by high spatial resolution, high frame rate and high dimensionality of scene representation. Processing such content would result in a tremendous increase in terms of memory storage, memory access rate, and processing power.

Accordingly, there is a need to design coding tools for more efficiently processing next generation video content.

The present invention seeks to provide a method for generating a more accurate prediction block.

In addition, the present invention is to provide a method for reducing the data amount of the residual signal.

In addition, the present invention is to provide a method for modifying the prediction signal using the reference residual signal in performing the intra prediction.

The present invention also provides a method of deriving a residual signal from other coding information transmitted without transmitting the residual signal.

In addition, the present invention is to provide a method for searching for a reference block for intra prediction using the information of the neighboring region which has already been reconstructed, and generating a reference residual signal using the same.

In addition, the present invention is to provide a method for designating a portion of the restoration area as a template and searching for a similar area using the template.

In addition, the present invention is to provide a method for searching a reference region by using the transmitted position information.

In order to solve the above technical problem,

The present invention provides a method of designing a coding tool for high efficiency compression.

In addition, the present invention provides a method for generating a more accurate prediction block.

The present invention also provides a method of reducing the data amount of the residual signal.

The present invention also provides a method of modifying a prediction signal using a reference residual signal in performing intra prediction.

In addition, the present invention provides a method of searching for a reference block for intra prediction using information of a neighboring region that has already been reconstructed, and generating a reference residual signal using the same.

In addition, the present invention provides a method of designating a portion of a restoration area as a template and searching for a similar area using the template.

The present invention also provides a method for searching a reference region by using transmitted location information.

The present invention can reduce the bit rate by transmitting a residual signal at a low cost when using the intra prediction method when coding a still image or a video.

In addition, the present invention can generate a more accurate prediction block by modifying the prediction signal using the reference residual signal, thereby reducing the data amount of the residual signal, thereby reducing the amount of energy transmitted thereto. have.

In addition, the present invention can reduce the amount of data to be transmitted by deriving the residual signal from other coding information transmitted without transmitting the residual signal.

In addition, the present invention can generate a more accurate prediction block by searching for a reference block for intra prediction using information of the neighboring region which has already been reconstructed and generating a reference residual signal using the same.

In addition, the present invention can improve the prediction accuracy by designating a portion of the reconstructed region as a template and searching for a similar region using the template.

In addition, the present invention can improve the prediction accuracy by searching the reference region using the transmitted position information.

1 is a schematic block diagram of an encoder in which encoding of a video signal is performed as an embodiment to which the present invention is applied.

2 is a schematic block diagram of a decoder in which decoding of a video signal is performed as an embodiment to which the present invention is applied.

3 is a diagram for describing a division structure of a coding unit according to an embodiment to which the present invention is applied.

4 is a diagram for describing a prediction unit according to an embodiment to which the present invention is applied.

5 is a diagram for describing an intra prediction method according to an embodiment to which the present invention is applied.

6 is a diagram for describing a prediction direction according to an intra prediction mode according to an embodiment to which the present invention is applied.

7 is a schematic block diagram of an encoder in which encoding of a video signal is performed, according to another embodiment to which the present invention is applied.

8 is a schematic block diagram of a decoder in which decoding of a video signal is performed as another embodiment to which the present invention is applied.

FIG. 9 is a diagram for describing a method of searching for a reference block using surrounding restoration information according to an embodiment to which the present invention is applied.

FIG. 10 is an embodiment to which the present invention is applied and is an encoding flowchart illustrating a process of modifying a prediction signal using a reference residual signal in intra prediction.

FIG. 11 is an embodiment to which the present invention is applied and is an encoding flowchart illustrating a process of compensating a residual signal using a reference residual signal in intra prediction.

12 is a diagram for describing a method of searching for a reference block using location information according to an embodiment to which the present invention is applied.

FIG. 13 is an embodiment to which the present invention is applied and is an encoding flowchart illustrating a process of modifying a prediction signal using a reference residual signal in intra prediction.

14 is an embodiment to which the present invention is applied and is a decoding flowchart illustrating a process of compensating a residual signal using a reference residual signal in intra prediction.

FIG. 15 is a schematic block diagram of an encoder or a decoder that performs coding using a residual signal derived from reconstruction information according to another embodiment to which the present invention is applied.

16 is a flowchart illustrating a method of encoding a video signal using a residual signal derived from reconstruction information according to another embodiment to which the present invention is applied.

17 is a flowchart illustrating a method of reconstructing a video signal by inducing a residual signal according to another embodiment to which the present invention is applied.

FIG. 18 is a flowchart illustrating a method of encoding a video signal using a residual signal derived based on a searched reference block and searching for a reference block using position information according to another embodiment to which the present invention is applied.

19 is a flowchart illustrating a method of reconstructing a video signal by searching for a reference block using position information and inducing a residual signal based on the found reference block according to another embodiment to which the present invention is applied.

The present invention provides a method of decoding a video signal, the method comprising: searching for a reference block for a current block, wherein the reference block is already reconstructed in the current frame; Generating a reference prediction signal representing a prediction value for the searched reference block; Generating a reference residual signal by subtracting the reference prediction signal from the reference block; Compensating for the residual signal of the current block obtained from the video signal based on the reference residual signal; And reconstructing the current block by adding the compensated residual signal and the prediction signal of the current block.

In the present invention, the reference prediction signal is generated according to the intra prediction mode of the current block.

Also, in the present invention, the reference block is searched based on a template, and the template has a predetermined shape and is composed of pixels adjacent to the current block.

In the present invention, the reference block is searched based on the positional information, and the positional information is extracted from the video signal.

The present invention may further include extracting flag information indicating whether a residual signal exists from the video signal, and is performed when the residual signal exists according to the flag information. .

In addition, the present invention provides a method of encoding a video signal, comprising: searching for a reference block for a current block, wherein the reference block is already reconstructed in the current frame; Generating a reference residual signal of the reference block; Generating a prediction signal of the current block according to an intra prediction mode of the current block; Updating the prediction signal of the current block by adding the reference residual signal to the prediction signal of the current block; And generating a residual signal of the current block based on the updated prediction signal.

The present invention may further include generating a reference prediction signal indicating a prediction value for the searched reference block, wherein the reference prediction signal is generated according to an intra prediction mode of the current block.

In addition, the present invention includes the steps of encoding the position information of the reference block; And transmitting the position information of the reference block.

In addition, the present invention includes the steps of performing a transform on the residual signal of the current block; Performing quantization on the converted residual signal; And performing entropy encoding on the quantized residual signal.

In addition, the present invention provides a device for decoding a video signal, search for a reference block for the current block, generates a reference prediction signal representing a prediction value for the searched reference block, the reference block in the reference prediction signal A reference residual signal generator for generating a reference residual signal by subtracting a; A residual signal compensator configured to compensate the residual signal of the current block obtained from the video signal based on the reference residual signal; And a reconstruction unit configured to reconstruct the current block by adding the compensated residual signal and the prediction signal of the current block, wherein the reference block is already reconstructed in the current frame.

In addition, the present invention provides a device for encoding a video signal, search for a reference block for the current block, generates a reference residual signal of the reference block, according to the intra prediction mode of the current block A prediction unit generating a prediction signal and updating the prediction signal of the current block by adding the reference residual signal to the prediction signal of the current block; And a residual signal acquirer configured to generate a residual signal of the current block based on the updated prediction signal.

In the present invention, the prediction unit generates a reference prediction signal indicating a prediction value for the searched reference block, and the reference prediction signal is generated according to the intra prediction mode of the current block.

In addition, the present invention, the conversion unit for performing the transformation on the residual signal of the current block; A quantization unit performing quantization on the converted residual signal; And an entropy encoding unit for performing entropy encoding on the quantized residual signal.

Hereinafter, the configuration and operation of the embodiments of the present invention with reference to the accompanying drawings, the configuration and operation of the present invention described by the drawings will be described as one embodiment, whereby the technical spirit of the present invention And its core composition and operation are not limited.

In addition, the terminology used in the present invention was selected as a general term widely used as possible now, in a specific case will be described using terms arbitrarily selected by the applicant. In such a case, since the meaning is clearly described in the detailed description of the part, it should not be interpreted simply by the name of the term used in the description of the present invention, and it should be understood that the meaning of the term should be interpreted. .

In addition, terms used in the present invention may be replaced for more appropriate interpretation when there are general terms selected to describe the invention or other terms having similar meanings. For example, signals, data, samples, pictures, frames, blocks, etc. may be appropriately replaced and interpreted in each coding process. In addition, partitioning, decomposition, splitting, and division may be appropriately replaced and interpreted in each coding process.

Referring to FIG. 1, the encoder 100 may include an image splitter 110, a transformer 120, a quantizer 130, an inverse quantizer 140, an inverse transformer 150, a filter 160, and a decoder. It may include a decoded picture buffer (DPB) 170, an inter predictor 180, an intra predictor 185, and an entropy encoder 190.

The image divider 110 may divide an input image (or a picture or a frame) input to the encoder 100 into one or more processing units. For example, the processing unit may be a Coding Tree Unit (CTU), a Coding Unit (CU), a Prediction Unit (PU), or a Transform Unit (TU).

However, the terms are only used for the convenience of description of the present invention, the present invention is not limited to the definition of the terms. In addition, in the present specification, for convenience of description, the term coding unit is used as a unit used in encoding or decoding a video signal, but the present invention is not limited thereto and may be appropriately interpreted according to the present invention.

The encoder 100 may generate a residual signal by subtracting a prediction signal output from the inter predictor 180 or the intra predictor 185 from the input image signal and generate the residual signal. The dual signal is transmitted to the converter 120.

The transform unit 120 may generate a transform coefficient by applying a transform technique to the residual signal. The conversion process may be applied to pixel blocks having the same size as the square, or may be applied to blocks of variable size rather than square.

The quantization unit 130 may quantize the transform coefficients and transmit the quantized coefficients to the entropy encoding unit 190, and the entropy encoding unit 190 may entropy code the quantized signal and output the bitstream.

The quantized signal output from the quantization unit 130 may be used to generate a prediction signal. For example, the quantized signal may restore the residual signal by applying inverse quantization and inverse transformation through an inverse quantization unit 140 and an inverse transformation unit 150 in a loop. A reconstructed signal may be generated by adding the reconstructed residual signal to a prediction signal output from the inter predictor 180 or the intra predictor 185.

Meanwhile, in the compression process as described above, adjacent blocks are quantized by different quantization parameters, thereby causing deterioration of the block boundary. This phenomenon is called blocking artifacts, which is one of the important factors in evaluating image quality. In order to reduce such deterioration, a filtering process may be performed. Through this filtering process, the image quality can be improved by removing the blocking degradation and reducing the error of the current picture.

The filtering unit 160 applies filtering to the reconstruction signal and outputs it to the reproduction apparatus or transmits the decoded picture buffer to the decoding picture buffer 170. The filtered signal transmitted to the decoded picture buffer 170 may be used as the reference picture in the inter predictor 180. As such, by using the filtered picture as a reference picture in the inter prediction mode, not only image quality but also encoding efficiency may be improved.

The decoded picture buffer 170 may store the filtered picture for use as a reference picture in the inter prediction unit 180.

The inter prediction unit 180 performs temporal prediction and / or spatial prediction to remove temporal redundancy and / or spatial redundancy with reference to a reconstructed picture. Here, since the reference picture used to perform the prediction is a transformed signal that has been quantized and dequantized in units of blocks at the time of encoding / decoding, a blocking artifact or a ringing artifact may exist. have.

Accordingly, the inter prediction unit 180 may interpolate the signals between pixels in sub-pixel units by applying a lowpass filter in order to solve performance degradation due to discontinuity or quantization of such signals. Herein, the subpixels mean virtual pixels generated by applying an interpolation filter, and the integer pixels mean actual pixels existing in the reconstructed picture. As the interpolation method, linear interpolation, bi-linear interpolation, wiener filter, or the like may be applied.

The interpolation filter may be applied to a reconstructed picture to improve the precision of prediction. For example, the inter prediction unit 180 generates an interpolation pixel by applying an interpolation filter to integer pixels, and uses an interpolated block composed of interpolated pixels as a prediction block. You can make predictions.

The intra predictor 185 may predict the current block by referring to samples around the block to which current encoding is to be performed. The intra prediction unit 185 may perform the following process to perform intra prediction. First, reference samples necessary for generating a prediction signal may be prepared. The prediction signal may be generated using the prepared reference sample. Then, the prediction mode is encoded. In this case, the reference sample may be prepared through reference sample padding and / or reference sample filtering. Since the reference sample has been predicted and reconstructed, there may be a quantization error. Accordingly, the reference sample filtering process may be performed for each prediction mode used for intra prediction to reduce such an error.

An embodiment of the present invention provides a method of predicting a residual signal generated during intra prediction from an image which is already reconstructed from a surrounding.

In an embodiment, the region most similar to the surrounding region of the region to be coded is searched in the reconstructed image, and when the region most similar to the region is searched, the prediction residual signal of the region to which the residual signal of the region is currently coded. Can be utilized as

In addition, another embodiment of the present invention may receive the position information most similar to the peripheral region of the region to be coded from the encoder, and utilize the residual signal of the region as a predictive residual signal of the region to be currently coded.

A prediction signal generated by the inter predictor 180 or the intra predictor 185 may be used to generate a reconstruction signal or to generate a residual signal.

2, the decoder 200 includes an entropy decoding unit 210, an inverse quantizer 220, an inverse transform unit 230, a filtering unit 240, and a decoded picture buffer unit (DPB) 250. ), An inter predictor 260, and an intra predictor 265.

The reconstructed video signal output through the decoder 200 may be reproduced through the reproducing apparatus.

The decoder 200 may receive a signal output from the encoder 100 of FIG. 1, and the received signal may be entropy decoded through the entropy decoding unit 210.

The inverse quantization unit 220 obtains a transform coefficient from the entropy decoded signal using the quantization step size information.

The inverse transformer 230 inversely transforms a transform coefficient to obtain a residual signal.

A reconstructed signal is generated by adding the obtained residual signal to a prediction signal output from the inter predictor 260 or the intra predictor 265.

The filtering unit 240 applies filtering to the reconstructed signal and outputs the filtering to the reproducing apparatus or transmits it to the decoded picture buffer unit 250. The filtered signal transmitted to the decoded picture buffer unit 250 may be used as the reference picture in the inter predictor 260.

In the present specification, the embodiments described by the filtering unit 160, the inter prediction unit 180, and the intra prediction unit 185 of the encoder 100 are respectively the filtering unit 240, the inter prediction unit 260, and the decoder. The same may be applied to the intra predictor 265.

The encoder may split one image (or picture) in units of a rectangular Coding Tree Unit (CTU). In addition, one CTU is sequentially encoded according to a raster scan order.

For example, the size of the CTU may be set to any one of 64x64, 32x32, and 16x16, but the present invention is not limited thereto. The encoder may select and use the size of the CTU according to the resolution of the input video or the characteristics of the input video. The CTU may include a coding tree block (CTB) for a luma component and a coding tree block (CTB) for two chroma components corresponding thereto.

One CTU may be decomposed into a quadtree (QT) structure. For example, one CTU may be divided into four units having a square shape and each side is reduced by half in length. The decomposition of this QT structure can be done recursively.

Referring to FIG. 3, a root node of a QT may be associated with a CTU. The QT may be split until it reaches a leaf node, where the leaf node may be referred to as a coding unit (CU).

A CU may mean a basic unit of coding in which an input image is processed, for example, intra / inter prediction is performed. The CU may include a coding block (CB) for a luma component and a CB for two chroma components corresponding thereto. For example, the size of the CU may be determined as any one of 64x64, 32x32, 16x16, and 8x8. However, the present invention is not limited thereto, and in the case of a high resolution image, the size of the CU may be larger or more diverse.

Referring to FIG. 3, the CTU corresponds to a root node and has the smallest depth (ie, level 0) value. The CTU may not be divided according to the characteristics of the input image. In this case, the CTU corresponds to a CU.

The CTU may be decomposed in QT form, and as a result, lower nodes having a depth of level 1 may be generated. And, a node that is no longer partitioned (ie, a leaf node) in a lower node having a depth of level 1 corresponds to a CU. For example, in FIG. 3 (b), CU (a), CU (b) and CU (j) corresponding to nodes a, b and j are divided once in the CTU and have a depth of level 1. FIG.

At least one of the nodes having a depth of level 1 may be split into QT again. And, a node that is no longer partitioned (ie, a leaf node) in a lower node having a level 2 depth corresponds to a CU. For example, in FIG. 3 (b), CU (c), CU (h), and CU (i) corresponding to nodes c, h and i are divided twice in the CTU and have a depth of level 2. FIG.

In addition, at least one of the nodes having a depth of 2 may be divided into QTs. And, a node that is no longer partitioned (ie, a leaf node) in a lower node having a depth of level 3 corresponds to a CU. For example, in FIG. 3 (b), CU (d), CU (e), CU (f), and CU (g) corresponding to nodes d, e, f, and g are divided three times in the CTU, and level 3 Has a depth of

In the encoder, the maximum size or the minimum size of the CU may be determined according to characteristics (eg, resolution) of the video image or in consideration of encoding efficiency. Information about this or information capable of deriving the information may be included in the bitstream. A CU having a maximum size may be referred to as a largest coding unit (LCU), and a CU having a minimum size may be referred to as a smallest coding unit (SCU).

In addition, a CU having a tree structure may be hierarchically divided with predetermined maximum depth information (or maximum level information). Each partitioned CU may have depth information. Since the depth information indicates the number and / or degree of division of the CU, the depth information may include information about the size of the CU.

Since the LCU is divided into QT forms, the size of the SCU can be obtained by using the size and maximum depth information of the LCU. Or conversely, using the size of the SCU and the maximum depth information of the tree, the size of the LCU can be obtained.

For one CU, information indicating whether the corresponding CU is split may be delivered to the decoder. For example, the information may be defined as a split flag and may be represented by a syntax element "split_cu_flag". The division flag may be included in all CUs except the SCU. For example, if the split flag value is '1', the corresponding CU is divided into four CUs again. If the split flag value is '0', the CU is not divided any more and the coding process for the CU is not divided. Can be performed.

In the embodiment of FIG. 3, the division process of the CU has been described as an example, but the QT structure described above may also be applied to the division process of a transform unit (TU) which is a basic unit for performing transformation.

The TU may be hierarchically divided into a QT structure from a CU to be coded. For example, a CU may correspond to a root node of a tree for a transform unit (TU).

Since the TU is divided into QT structures, the TU divided from the CU may be divided into smaller lower TUs. For example, the size of the TU may be determined by any one of 32x32, 16x16, 8x8, and 4x4. However, the present invention is not limited thereto, and in the case of a high resolution image, the size of the TU may be larger or more diverse.

For one TU, information indicating whether the corresponding TU is divided may be delivered to the decoder. For example, the information may be defined as a split transform flag and may be represented by a syntax element "split_transform_flag".

The division conversion flag may be included in all TUs except the TU of the minimum size. For example, if the value of the division conversion flag is '1', the corresponding TU is divided into four TUs again. If the value of the division conversion flag is '0', the corresponding TU is no longer divided.

As described above, a CU is a basic unit of coding in which intra prediction or inter prediction is performed. In order to code an input image more effectively, a CU may be divided into prediction units (PUs).

The PU is a basic unit for generating a prediction block, and may generate different prediction blocks in PU units within one CU. The PU may be divided differently according to whether an intra prediction mode or an inter prediction mode is used as a coding mode of a CU to which the PU belongs.

The PU is divided differently according to whether an intra prediction mode or an inter prediction mode is used as a coding mode of a CU to which the PU belongs.

FIG. 4A illustrates a PU when an intra prediction mode is used, and FIG. 4B illustrates a PU when an inter prediction mode is used.

Referring to FIG. 4 (a), assuming that a size of one CU is 2Nx2N (N = 4,8,16,32), one CU may be divided into two types (ie, 2Nx2N or NxN). Can be.

Here, when divided into 2N × 2N type PU, it means that only one PU exists in one CU.

On the other hand, when divided into N × N type PU, one CU is divided into four PUs, and different prediction blocks are generated for each PU unit. However, the division of the PU may be performed only when the size of the CB for the luminance component of the CU is the minimum size (that is, the CU is the SCU).

Referring to FIG. 4 (b), assuming that a size of one CU is 2N × 2N (N = 4,8,16,32), one CU has 8 PU types (ie, 2Nx2N, NxN, 2NxN). , Nx2N, nLx2N, nRx2N, 2NxnU, 2NxnD).

Similar to intra prediction, PU splitting in the form of NxN may be performed only when the size of the CB for the luminance component of the CU is the minimum size (that is, the CU is the SCU).

In inter prediction, 2NxN type partitioning in the horizontal direction and Nx2N type PU partitioning in the vertical direction are supported.

In addition, it supports PU partitions of nLx2N, nRx2N, 2NxnU, and 2NxnD types, which are Asymmetric Motion Partition (AMP). Here, 'n' means a 1/4 value of 2N. However, AMP cannot be used when the CU to which the PU belongs is a CU of the minimum size.

In order to efficiently encode an input image within one CTU, an optimal partitioning structure of a coding unit (CU), a prediction unit (PU), and a transformation unit (TU) is subjected to the following process to perform a minimum rate-distortion. It can be determined based on the value. For example, looking at an optimal CU partitioning process in a 64x64 CTU, rate-distortion cost can be calculated while partitioning from a 64x64 CU to an 8x8 CU. The specific process is as follows.

1) The partition structure of the optimal PU and TU that generates the minimum rate-distortion value is determined by performing inter / intra prediction, transform / quantization, inverse quantization / inverse transform, and entropy encoding for a 64x64 CU.

2) Partition the 64x64 CU into four 32x32 CUs and determine the optimal PU and TU partitioning structure that generates the minimum rate-distortion value for each 32x32 CU.

3) The 32x32 CU is subdivided into four 16x16 CUs, and a partition structure of an optimal PU and TU that generates a minimum rate-distortion value for each 16x16 CU is determined.

4) Subdivide the 16x16 CU into four 8x8 CUs, and determine the optimal PU and TU partitioning structure that generates the minimum rate-distortion value for each 8x8 CU.

5) Compare the sum of the rate-distortion values of the 16x16 CUs calculated in step 3) with the rate-distortion values of the four 8x8 CUs calculated in step 4) to determine the optimal CU in the 16x16 block. Determine the partition structure. This process is similarly performed for the remaining three 16x16 CUs.

6) Compare the sum of the rate-distortion values of the 32x32 CUs calculated in 2) with the rate-distortion values of the four 16x16 CUs obtained in 5) above, Determine the partition structure. Do this for the remaining three 32x32 CUs.

7) Finally, compare the sum of the rate-distortion values of the 64x64 CUs calculated in 1) with the rate-distortion values of the four 32x32 CUs obtained in 6) above, and then optimize the result within the 64x64 block. Determine the partition structure of the CU.

In the intra prediction mode, a prediction mode is selected in units of PUs, and prediction and reconstruction are performed in units of actual TUs for the selected prediction mode.

TU means a basic unit in which actual prediction and reconstruction are performed. The TU includes a transform block (TB) for a luma component and a TB for two chroma components corresponding thereto.

In the example of FIG. 3, as one CTU is divided into quadtree structures to generate a CU, the TUs are hierarchically divided into quadtree structures from one CU to be coded.

Since the TU is divided into quadtree structures, the TU divided from the CU may be divided into smaller lower TUs. In HEVC, the size of the TU may be set to any one of 32 × 32, 16 × 16, 8 × 8, and 4 × 4.

Referring back to FIG. 3, it is assumed that a root node of the quadtree is associated with a CU. The quadtree is split until it reaches a leaf node, and the leaf node corresponds to a TU.

In more detail, a CU corresponds to a root node and has a smallest depth (that is, depth = 0). The CU may not be divided according to the characteristics of the input image. In this case, the CU corresponds to a TU.

The CU may be divided into quad tree shapes, resulting in lower nodes having a depth of 1 (depth = 1). In addition, a node (ie, a leaf node) that is no longer divided in a lower node having a depth of 1 corresponds to a TU. For example, in FIG. 3B, TU (a), TU (b), and TU (j) corresponding to nodes a, b, and j are divided once in a CU and have a depth of 1. FIG.

At least one of the nodes having a depth of 1 may be split into a quad tree again, resulting in lower nodes having a depth of 1 (ie, depth = 2). In addition, a node (ie, a leaf node) that is no longer divided in a lower node having a depth of 2 corresponds to a TU. For example, in FIG. 3B, TU (c), TU (h), and TU (i) corresponding to nodes c, h, and i are divided twice in a CU and have a depth of two.

In addition, at least one of the nodes having a depth of 2 may be divided into quad tree shapes, resulting in lower nodes having a depth of 3 (ie, depth = 3). And, a node that is no longer partitioned (ie, a leaf node) in a lower node having a depth of 3 corresponds to a CU. For example, in FIG. 3 (b), TU (d), TU (e), TU (f), and TU (g) corresponding to nodes d, e, f, and g are divided three times in a CU. Has depth.

A TU having a tree structure may be hierarchically divided with predetermined maximum depth information (or maximum level information). Each divided TU may have depth information. Since the depth information indicates the number and / or degree of division of the TU, it may include information about the size of the TU.

For one TU, information indicating whether the corresponding TU is split (for example, split TU flag split_transform_flag) may be delivered to the decoder. This partitioning information is included in all TUs except the smallest TU. For example, if the value of the flag indicating whether to split is '1', the corresponding TU is divided into four TUs again. If the value of the flag indicating whether to split is '0', the corresponding TU is no longer divided.

5 and 6 illustrate embodiments to which the present invention is applied. FIG. 5 is a diagram illustrating an intra prediction method, and FIG. 6 is a diagram illustrating a prediction direction according to an intra prediction mode.

Referring to FIG. 5, the decoder may derive an intra prediction mode of the current processing block (S501).

In intra prediction, the prediction direction may have a prediction direction with respect to the position of a reference sample used for prediction according to a prediction mode. In this specification, an intra prediction mode having a prediction direction is referred to as an intra_angular prediction mode or an intra directional mode. On the other hand, as an intra prediction mode having no prediction direction, there are an intra planner (INTRA_PLANAR) prediction mode and an intra DC (INTRA_DC) prediction mode.

Table 1 illustrates an intra prediction mode and related names, and FIG. 6 illustrates a prediction direction according to the intra prediction mode.

Table 1

Intra prediction mode	Associated name
0	Intra Planner (INTRA_PLANAR)
One	Intra DC (INTRA_DC)
2 ... 34	Intra directional 2 ... Intra directional 34 (INTRA_ANGULAR2 ... INTRA_ANGULAR34)

In intra prediction, prediction is performed on the current processing block based on the derived prediction mode. Since the reference sample used for the prediction and the specific prediction method vary according to the prediction mode, when the current block is encoded in the intra prediction mode, the decoder may derive the prediction mode of the current block to perform the prediction.

The decoder may check whether neighboring samples of the current processing block can be used for prediction and configure reference samples to be used for prediction (S502).

In intra prediction, neighboring samples of the current processing block are samples adjacent to the left boundary of the current processing block of size nSxnS and a total of 2xnS samples neighboring the bottom-left, top of the current processing block. A total of 2xnS samples neighboring the top-right sample and a sample adjacent to the boundary and one sample neighboring the top-left side of the current processing block.

However, some of the surrounding samples of the current processing block may not be decoded yet or may be available. In this case, the decoder can construct reference samples for use in prediction by substituting samples that are not available with the available samples.

The decoder may perform filtering of reference samples based on the intra prediction mode (S503).

Whether filtering of the reference sample is performed may be determined based on the size of the current processing block. In addition, the filtering method of the reference sample may be determined by the filtering flag transmitted from the encoder.

The decoder may generate a prediction block for the current processing block based on the intra prediction mode and the reference samples (S504). That is, the decoder predicts the current processing block based on the intra prediction mode derived in the intra prediction mode derivation step S501 and the reference samples obtained through the reference sample configuration step S502 and the reference sample filtering step S503. A block may be generated (ie, predictive sample generation).

In order to minimize the discontinuity of the boundary between the processing blocks when the current processing block is encoded in the INTRA_DC mode, the left boundary sample (ie, the sample in the prediction block adjacent to the left boundary) and the upper side of the prediction block in step S504. (top) boundary samples (i.e., samples in prediction blocks adjacent to the upper boundary) may be filtered.

In addition, in operation S504, filtering may be applied to the left boundary sample or the upper boundary sample in the vertical direction mode and the horizontal mode among the intra directional prediction modes similarly to the INTRA_DC mode.

In more detail, when the current processing block is encoded in the vertical mode or the horizontal mode, the value of the prediction sample may be derived based on a reference sample located in the prediction direction. In this case, a boundary sample which is not located in the prediction direction among the left boundary sample or the upper boundary sample of the prediction block may be adjacent to a reference sample which is not used for prediction. That is, the distance from the reference sample not used for prediction may be much closer than the distance from the reference sample used for prediction.

Thus, the decoder may adaptively apply filtering to left boundary samples or upper boundary samples depending on whether the intra prediction direction is vertical or horizontal. That is, when the intra prediction direction is the vertical direction, the filtering may be applied to the left boundary samples, and when the intra prediction direction is the horizontal direction, the filtering may be applied to the upper boundary samples.

Referring to FIG. 7, the encoder to which the present invention is applied includes a predictor 700, a transformer 730, a quantizer 740, an inverse quantizer 750, an inverse transformer 760, and a DPB 770. can do. The prediction unit 700 may include at least one of a reference residual signal generator 710, a reference reconstruction signal generator 711, a reference prediction signal generator 712, and an intra predictor 720. have.

On the other hand, the adder / subtractor does not have a separate identification mark, but it can be used where necessary to calculate the sum and difference of the signal. In addition, the predictor 700 may include both the intra predictor and the inter predictor as described above. In an embodiment of the present invention, the intra predictor is described, but the present invention is not limited thereto.

In addition, the converter 730, the quantization unit 740, the inverse quantization unit 750, the inverse transform unit 760, and the DPB 770 may be applied to the contents described with reference to FIGS. 1 and 2. Overlapping descriptions will be omitted.

The present invention proposes a method of predicting a residual signal generated during intra coding from an already reconstructed image of a surrounding.

In one embodiment of the present invention, the region most similar to the peripheral region of the region to be encoded or decoded is searched in the reconstructed image, and if the most similar region is found, the residual signal of the region is currently encoded or decoded. It can be used as a predictive residual signal of a region.

First, the reference reconstruction signal generator 711 may search for a reference block for the current block in the reconstructed region in the current frame. For example, to search the reference block, a template or location information may be used. Specific embodiments thereof will be described in detail with reference to FIGS. 9 and 12. A reference reconstruction signal Recon _ref may be generated from the found reference block. Here, since the reference block is a signal that has already been restored, it may be referred to as a reference recovery signal.

After searching for the reference block, the reference prediction signal generator 712 may generate a reference prediction signal Pre _ref using the prediction mode of the current block. For example, when the prediction mode of the current block is an intra vertical mode, a reference prediction signal may be generated based on the intra vertical mode.

As another example, the reference prediction signal generator 712 may generate a reference prediction signal by using the peripheral information of the reference block. For example, coding information of at least one of an upper block, a lower block, a left block, or a right block of the reference block may be used. Here, the coding information may include at least one of pixel information or prediction mode information.

The reference residual signal generator 710 may generate a reference residual signal Res _ref by subtracting the reference prediction signal from the reference reconstruction signal.

Meanwhile, the intra predictor 720 may perform intra prediction according to the prediction mode determined for the current block, and generate a prediction signal Pre _curr of the current block through the intra prediction.

The present invention may update or correct the prediction signal Pred _curr of the current block to generate a more accurate prediction signal. For example, the prediction signal Pre _curr of the current block may be updated by using a reference residual signal Res _ref . That is, the updated prediction signal Pre _update may be generated by adding the reference residual signal Res _ref to the prediction signal Pred _curr of the current block.

By subtracting the updated prediction signal (Pred _update) from the source signal to generate a residual signal (Res _curr). The residual signal Res _curr may be converted by the converter 730, quantized by the quantizer 740, and entropy encoded by an entropy encoding unit (not shown).

On the other hand, the quantization unit 740, a residual signal (Res _curr) is quantized by the inverse quantization by the inverse again positive unit 750 may be inverse transformed by the inverse transformation unit (760). The residual signal Res _curr that has undergone the above process is added to the reference prediction signal Pre _ref generated by the reference prediction signal generator 712 to generate a reconstruction signal, and the generated reconstruction signal is a DPB 770. ) Can be stored.

As another example, the residual signal Res _curr may be added to a prediction signal Pre _curr of the current block generated by the intra predictor 720 to generate a reconstruction signal, and the generated reconstruction signal is DPB ( 770 may be stored.

The stored reconstruction signal may be used for inter prediction or intra prediction.

Referring to FIG. 8, a decoder to which the present invention is applied includes a reference residual signal generator 810, a reference reconstruction signal generator 811, a reference prediction signal generator 812, a predictor 820, and an inverse quantizer ( 850, an inverse transform unit 860, and a DPB 870.

On the other hand, the adder / subtractor does not have a separate identification mark, but it can be used where necessary to calculate the sum and difference of the signal. In addition, the prediction unit 820 may include both the intra prediction unit and the inter prediction unit described above. In an embodiment of the present invention, the prediction unit 820 is described based on the intra prediction unit, but the present invention is not limited thereto.

The inverse quantization unit 850, the inverse transform unit 860, and the DPB 870 may be applied to the contents described with reference to FIGS. 1, 2, and 7, and redundant descriptions thereof will be omitted.

First, the reference reconstruction signal generator 811 may search for a reference block with respect to the current block in a reconstructed region in the current frame. For example, to search the reference block, a template or location information may be used. Specific embodiments thereof will be described in detail with reference to FIGS. 9 and 12. A reference reconstruction signal Recon _ref may be generated from the found reference block. Here, since the reference block is a signal that has already been restored, it may be referred to as a reference recovery signal.

After searching the reference block, the reference prediction signal generator 812 may generate a reference prediction signal Pre _ref using the prediction mode of the current block. For example, when the prediction mode of the current block is an intra vertical mode, a reference prediction signal may be generated based on the intra vertical mode.

As another example, the reference prediction signal generator 812 may generate a reference prediction signal using the surrounding information of the reference block. For example, coding information of at least one of an upper block, a lower block, a left block, or a right block of the reference block may be used. Here, the coding information may include at least one of pixel information or prediction mode information.

The reference residual signal generator 810 may generate a reference residual signal Res _ref by subtracting the reference prediction signal from the reference reconstruction signal.

Meanwhile, a decoder to which the present invention is applied may receive a bitstream, and the bitstream may obtain a residual signal Res _curr through the inverse quantizer 850 and the inverse transformer 860.

The present invention may compensate for the residual signal Res _curr for more accurate signal recovery. For example, the residual signal Res _curr may be compensated using the residual signal of the reference block similar to the current block. That is, the residual signal Res _curr may be compensated by adding the reference residual signal acquired through the reference residual signal generator 810 to the residual signal Res _curr .

The prediction unit 820 may perform prediction according to the prediction mode determined for the current block, and may generate a prediction signal Pred _curr of the current block through the prediction.

The video signal may be reconstructed by adding the predicted signal Pred _curr and the compensated residual signal.

In another embodiment of the present invention, the encoder receives the coordinate information most similar to the peripheral region of the region to be encoded or decoded, and utilizes the residual signal of the region as a predictive residual signal of the region to be currently encoded or decoded. have.

The present invention can search for a reference block within a reconstructed area of the current frame using a template. Here, the template may be defined in a predetermined form, for example, may have a form consisting of pixels adjacent to the upper side and the left side of the current block as shown in FIG. 9, but the present invention is not limited thereto.

Referring to FIG. 9, the encoder or the decoder may find a template _ref by searching an area most similar to the template _curr . The encoder or decoder may determine a reference block by using the template _ref for a position corresponding to the current block.

After determining the reference block, the encoder or decoder may perform the following process as described with reference to FIG. 7 or 8.

For example, the decoder generates a reference prediction signal Pre _ref using the prediction mode of the current block transmitted from the encoder and the surrounding information of the reference block, and subtracts the reference prediction signal Pred _ref from the reference block. The reference residual signal Res _ref may be generated.

The residual signal can be compensated by adding the residual signal Res _curr transmitted from the encoder and the reference residual signal Res _ref . The compensated residual signal may be combined with the prediction signal of the current block to generate a reconstruction signal Recon _curr . If this is expressed as an equation, Equation 1 below.

Equation 1

The present invention can reduce the bit rate by predicting the residual signal necessary for video decoding from the peripheral reconstruction information. Information necessary for decoding in the decoder can be largely classified into mode information and pixel information. The mode information may mean information other than pixel data necessary for image decoding. For example, the mode information may include intra prediction mode information, MPM information, block size information, QP information, and the like. The pixel information may mean a residual signal indicating a difference between an original signal and a prediction signal. The residual signal may be represented as information in the pixel domain through entropy decoding, inverse quantization, and inverse transformation, which may be combined with a prediction signal to generate a reconstruction signal.

According to the present invention, a residual signal can be derived using an already reconstructed pixel, thereby saving the amount of information transmitted to the decoder.

The method proposed in the present invention can be used to encode or decode each component (RGB, YCbCr, etc.) of a format having various color difference configurations.

In addition, the method proposed in the present invention can determine whether to use the flag signal.

In addition, the method proposed by the present invention can determine whether to use the specific conditions or a combination of specific conditions of encoding or decoding.

The encoder to which the present invention is applied may search for a reference block for the current block in the reconstructed region in the current frame (S1010). For example, to search the reference block, a template or location information may be used. A reference reconstruction signal may be generated from the found reference block.

After searching for the reference block, the encoder can generate a reference prediction signal using the prediction mode of the current block (S1020). For example, when the prediction mode of the current block is an intra vertical mode, a reference prediction signal may be generated based on the intra vertical mode.

The encoder may generate a reference residual signal by subtracting a reference prediction signal from the reference reconstruction signal (S1030).

Meanwhile, the encoder may perform intra prediction according to the prediction mode determined for the current block, and generate a prediction signal of the current block through the intra prediction (S1040).

The encoder may update the prediction signal of the current block by using the reference residual signal. That is, the updated prediction signal may be generated by adding the reference residual signal to the prediction signal of the current block (S1050).

The encoder may generate a residual signal by subtracting the updated prediction signal from the original signal (S1060). The residual signal may be transformed through a transformer, quantized through a quantizer, and entropy encoded through an entropy encoder.

The decoder to which the present invention is applied may search for a reference block for the current block in the reconstructed region in the current frame (S1110). For example, to search the reference block, a template or location information may be used. A reference reconstruction signal may be generated from the found reference block.

After searching the reference block, the decoder may generate a reference prediction signal using the prediction mode of the current block (S1120). For example, when the prediction mode of the current block is an intra vertical mode, a reference prediction signal may be generated based on the intra vertical mode.

The decoder may generate a reference residual signal by subtracting the reference prediction signal from the reference reconstruction signal (S1130), and may generate more accurate reconstruction by generating a reconstruction signal based on the reference residual signal.

In detail, the decoder may acquire a residual signal on a pixel domain by performing entropy decoding, inverse quantization, and inverse transformation on a residual signal transmitted from an encoder (S1140), and using the reference residual signal, the pixel The residual signal on the domain may be compensated for (S1150).

In operation S1160, a reconstruction signal may be generated by adding the predicted signal for the current block and the compensated residual signal.

In another embodiment of the present invention, the decoder may compensate for the prediction signal for the current block by using the generated reference residual signal. The compensated prediction signal is summed with the residual signal transmitted from the encoder to generate a reconstruction signal.

The present invention proposes a method of predicting a residual signal generated during intra coding from an already reconstructed image of a surrounding. The region most similar to the surrounding region of the region to be encoded or decoded is searched in the reconstructed image, and when the region most similar to the region is searched, the prediction residual of the region to be currently encoded or decoded the residual signal of the corresponding reference region. Can be used as a signal.

The present invention can search for a reference block most similar to the current block in a reconstructed area of the current frame. When the reference block is determined, the encoder can code position information of the reference block. Here, the position information of the reference block may be represented by coordinate information. Alternatively, the position information of the reference block may be represented by a vector. The location information may be transmitted to or derived from the decoder. The decoder may determine the reference block by using the location information when receiving the location information. Alternatively, when the location information is derived based on other coding information in the decoder, the reference block may be determined using the derived location information.

As another example, an area most similar to a peripheral area of the current block may be searched in a reconstructed area of the current frame, and the area corresponding to the current block may be determined therefrom. For example, the template of FIG. 9 may be used to search for the most similar area.

After determining the reference block, the encoder or the decoder may perform the following process as described with reference to FIG. 7 or 8.

The residual signal can be compensated by adding the residual signal Res _curr transmitted from the encoder and the reference residual signal Res _ref . The compensated residual signal may be combined with the prediction signal of the current block to generate a reconstruction signal Recon _curr . If this is expressed as an equation, Equation 2 below.

Equation 2

The encoder to which the present invention is applied may search for a reference block with respect to the current block in the reconstructed region in the current frame (S1310). For example, a template may be used to search the reference block. Here, the embodiment of FIG. 9 may be applied.

When the reference block is determined, the encoder can code position information of the reference block. Here, the position information of the reference block may be represented by coordinate information. Alternatively, the position information of the reference block may be represented by a vector. The location information may be transmitted to the decoder (S1380) or derived from the decoder.

In addition, a reference reconstruction signal may be generated from the reference block.

After searching the reference block, the encoder may generate a reference prediction signal using the prediction mode of the current block (S1320). For example, when the prediction mode of the current block is an intra vertical mode, a reference prediction signal may be generated based on the intra vertical mode.

The encoder may generate a reference residual signal by subtracting a reference prediction signal from the reference reconstruction signal (S1330).

Meanwhile, the encoder may perform intra prediction according to the prediction mode determined for the current block, and generate a prediction signal of the current block through the intra prediction (S1340).

The encoder may update the prediction signal of the current block by using the reference residual signal. That is, the updated prediction signal may be generated by adding the reference residual signal to the prediction signal of the current block (S1350).

The encoder may generate a residual signal by subtracting the updated prediction signal from the original signal (S1360). The residual signal may be transformed through a transform unit, quantized through a quantization unit, and entropy encoded through an entropy encoding unit (S1370). In this case, the position information of the reference block may be entropy encoded together with the residual signal and transmitted to the decoder (S1380).

The present invention can generate a reference prediction signal using location information of a reference block and a prediction mode of the current block.

First, the decoder may receive a bitstream including position information of a reference block with respect to the current block. The decoder may extract position information of the reference block from the bitstream. The location information of the reference block is entropy decoded (S1410), and the decoder may search for the reference block by using the location information of the reference block. Position information of the reference block may be represented by coordinate information. Alternatively, the position information of the reference block may be represented by a vector. A reference reconstruction signal may be generated from the found reference block.

After searching for the reference block, the decoder may generate a reference prediction signal using the prediction mode of the current block (S1420). For example, when the prediction mode of the current block is an intra vertical mode, a reference prediction signal may be generated based on the intra vertical mode.

The decoder may generate a reference residual signal by subtracting a reference prediction signal from the reference reconstruction signal (S1430), and may generate more accurate reconstruction by generating a reconstruction signal based on the reference residual signal.

In detail, the decoder may acquire a residual signal on a pixel domain by performing entropy decoding, inverse quantization, and inverse transformation on a residual signal transmitted from an encoder (S1440), and using the reference residual signal, the pixel The residual signal on the domain may be compensated for (S1450).

In operation S1460, a reconstruction signal may be generated by adding the predicted signal for the current block and the compensated residual signal.

Referring to FIG. 15, an encoder or decoder to which the present invention is applied may include a reference residual signal generator 1510, a reference reconstruction signal generator 1511, a reference prediction signal generator 1512, an intra predictor 1520, and a reconstruction. The unit 1530 and the DPB 1540 may be included.

On the other hand, the adder / subtractor does not have a separate identification mark, but it can be used where necessary to calculate the sum and difference of the signal. In FIG. 15, the intra prediction unit is described as a reference, but the present invention is not limited thereto.

In addition, the contents described with reference to FIGS. 1, 2, 7, and 8 may be applied to the restoration unit 1530 and the DPB 1540, and redundant description thereof will be omitted.

According to an embodiment of the present invention, a region most similar to a peripheral region of a region to be encoded or decoded is searched in a reconstructed image, and when a region most similar to the region is searched, a residual of the region to currently encode or decode a residual signal of the region. We propose a method to utilize the dual signal.

First, the reference reconstruction signal generator 1511 may search for a reference block for the current block in a reconstructed region in the current frame. For example, to search the reference block, a template or location information may be used. Specific embodiments thereof have been described in detail with reference to FIGS. 9 and 12. A reference reconstruction signal Recon _ref may be generated from the found reference block.

After searching for the reference block, the reference prediction signal generator 1512 may generate a reference prediction signal Pre _ref using the prediction mode of the current block. For example, when the prediction mode of the current block is an intra vertical mode, a reference prediction signal may be generated based on the intra vertical mode.

As another example, the reference prediction signal generator 1512 may generate a reference prediction signal by using the peripheral information of the reference block. For example, coding information of at least one of an upper block, a lower block, a left block, or a right block of the reference block may be used. Here, the coding information may include at least one of pixel information or prediction mode information.

The reference residual signal generator 1510 may generate a reference residual signal Res _ref by subtracting the reference prediction signal from the reference reconstruction signal. The reference residual signal Res _ref generated in this manner may be used as a residual signal of the current block. Therefore, the encoder can reduce the amount of transmitted bits by deriving from the peripheral information without transmitting the residual signal.

Meanwhile, the intra prediction unit 1520 may perform intra prediction according to the prediction mode determined for the current block, and generate a prediction signal Pre _curr of the current block through the intra prediction.

The reconstruction unit 1530 may generate a reconstruction signal by adding the reference residual signal Res _ref and the prediction signal Pred _curr of the current block. If this is expressed as an equation, Equation 3 below.

Equation 3

The present invention can reduce the bit rate by predicting the residual signal necessary for video decoding from the peripheral reconstruction information. Information necessary for decoding in the decoder can be largely classified into mode information and pixel information. The mode information may mean information other than pixel data necessary for image decoding. For example, the mode information may include intra prediction mode information, MPM information, block size information, QP information, and the like. The pixel information may mean a residual signal indicating a difference between an original signal and a prediction signal. By utilizing the present invention, the residual signal can be derived using the already reconstructed pixel, thereby saving the amount of information transmitted to the decoder.

The encoder to which the present invention is applied may search for a reference block with respect to the current block in the reconstructed region in the current frame (S1610). For example, a template may be used to search the reference block. A reference reconstruction signal may be generated from the found reference block.

After searching the reference block, the encoder may generate a reference prediction signal using the prediction mode of the current block (S1620). For example, when the prediction mode of the current block is an intra vertical mode, a reference prediction signal may be generated based on the intra vertical mode.

The encoder may generate a reference residual signal by subtracting a reference prediction signal from the reference reconstruction signal (S1630).

Meanwhile, the encoder may perform intra prediction according to the prediction mode determined for the current block, and generate a prediction signal of the current block through the intra prediction (S1640).

The encoder may generate a reconstruction signal by adding the reference residual signal and the prediction signal of the current block (S1650).

The encoder may determine whether to optimize rate distortion (S1660) while repeating the above process (S1660).

As a result of the determination, if it is determined to be optimal in terms of rate distortion, the corresponding coding information may be encoded and transmitted (S1670). Here, the coding information may include coding information such as a prediction mode.

The decoder to which the present invention is applied may receive a bitstream, and may determine whether a residual signal corresponding to a block to be currently decoded exists in the bitstream (S1710). For example, the decoder may determine this based on flag information indicating whether residual data exists.

As another example, the decoder may determine whether to derive the residual signal of the current block. For example, the decoder may determine this based on flag information indicating whether to derive the residual signal.

If it is determined that the residual signal exists in the bitstream or does not derive the residual signal of the current block, the decoder may perform decoding on the residual signal (S1720).

On the other hand, if it is determined that the residual signal does not exist in the bitstream or derives the residual signal of the current block, the decoder may derive the residual signal based on other information. have.

The decoder may search for a reference block for the current block in the reconstructed region in the current frame (S1730). For example, to search the reference block, a template or location information may be used. A reference reconstruction signal may be generated from the found reference block.

After searching for the reference block, the decoder may generate a reference prediction signal using the prediction mode of the current block (S1740). For example, when the prediction mode of the current block is an intra vertical mode, a reference prediction signal may be generated based on the intra vertical mode.

The decoder may generate a reference residual signal by subtracting a reference prediction signal from the reference reconstruction signal (S1750), and may generate more accurate reconstruction by generating a reconstruction signal based on the reference residual signal.

In operation S1760, a reconstruction signal may be generated by adding the prediction signal for the current block and the reference residual signal.

The encoder to which the present invention is applied may search for a reference block with respect to the current block in the reconstructed region in the current frame (S1810). For example, a template may be used to search the reference block. Here, the embodiment of FIG. 9 may be applied.

When the reference block is determined, the encoder can code position information of the reference block. Here, the position information of the reference block may be represented by coordinate information. Alternatively, the position information of the reference block may be represented by a vector. The location information may be transmitted to the decoder (S1870) or derived from the decoder.

After searching the reference block, the encoder can generate a reference prediction signal using the prediction mode of the current block (S1820). For example, when the prediction mode of the current block is an intra vertical mode, a reference prediction signal may be generated based on the intra vertical mode.

The encoder may generate a reference residual signal by subtracting a reference prediction signal from the reference reconstruction signal (S1830).

Meanwhile, the encoder may perform intra prediction according to the prediction mode determined for the current block, and generate a prediction signal of the current block through the intra prediction (S1840).

The encoder may generate a reconstruction signal by adding the reference residual signal and the prediction signal of the current block (S1850).

The encoder may determine whether to optimize rate distortion while repeating the above process (S1860).

As a result of the determination, if it is determined that it is optimal in terms of rate distortion, the corresponding coding information may be encoded and transmitted (S1870). Here, the coding information may include coding information such as position information of a reference block, a prediction mode, and the like.

First, a decoder to which the present invention is applied may receive a bitstream including position information of a reference block with respect to a current block, and determine whether a residual signal corresponding to a block to be currently decoded exists in the bitstream. It may be (S1910). For example, the decoder may determine this based on flag information indicating whether residual data exists.

If it is determined that the residual signal exists in the bitstream or does not derive the residual signal of the current block, the decoder may perform decoding on the residual signal (S1920).

Meanwhile, the decoder may extract position information of the reference block from the bitstream. The location information of the reference block is entropy decoded, and the decoder may search for the reference block by using the location information of the reference block (S1930). Position information of the reference block may be represented by coordinate information. Alternatively, the position information of the reference block may be represented by a vector. A reference reconstruction signal may be generated from the found reference block.

After searching for the reference block, the decoder may generate a reference prediction signal using the prediction mode of the current block (S1940). For example, when the prediction mode of the current block is an intra vertical mode, a reference prediction signal may be generated based on the intra vertical mode.

The decoder may generate a reference residual signal by subtracting a reference prediction signal from the reference reconstruction signal (S1950), and may generate a reconstruction signal based on the reference residual signal. That is, a reconstruction signal may be generated by adding the prediction signal for the current block and the reference residual signal (S1960).

In this manner, the amount of bits transmitted to the decoder can be reduced by deriving from the neighboring information of the current block without transmitting the residual signal.

As described above, the embodiments described herein may be implemented and performed on a processor, microprocessor, controller, or chip. For example, the functional units illustrated in FIGS. 1, 2, 7, 8, and 15 may be implemented by a computer, a processor, a microprocessor, a controller, or a chip.

In addition, the decoder and encoder to which the present invention is applied include a multimedia broadcasting transmitting and receiving device, a mobile communication terminal, a home cinema video device, a digital cinema video device, a surveillance camera, a video chat device, a real time communication device such as video communication, a mobile streaming device, Storage media, camcorders, video on demand (VoD) service providing devices, internet streaming service providing devices, three-dimensional (3D) video devices, video telephony video devices, and medical video devices, and the like, for processing video signals and data signals Can be used for

In addition, the processing method to which the present invention is applied can be produced in the form of a program executed by a computer, and can be stored in a computer-readable recording medium. Multimedia data having a data structure according to the present invention can also be stored in a computer-readable recording medium. The computer readable recording medium includes all kinds of storage devices for storing computer readable data. The computer-readable recording medium may include, for example, a Blu-ray disc (BD), a universal serial bus (USB), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device. Can be. The computer-readable recording medium also includes media embodied in the form of a carrier wave (eg, transmission over the Internet). In addition, the bit stream generated by the encoding method may be stored in a computer-readable recording medium or transmitted through a wired or wireless communication network.

As mentioned above, preferred embodiments of the present invention are disclosed for the purpose of illustration, and those skilled in the art can improve and change various other embodiments within the spirit and technical scope of the present invention disclosed in the appended claims below. , Replacement or addition would be possible.

Claims

In the method for decoding a video signal,

Searching for a reference block for the current block, wherein the reference block is already reconstructed in the current frame;

Generating a reference prediction signal representing a prediction value for the searched reference block;

Generating a reference residual signal by subtracting the reference prediction signal from the reference block;

Compensating for the residual signal of the current block obtained from the video signal based on the reference residual signal; And

Restoring the current block by adding the compensated residual signal and the prediction signal of the current block;

Method comprising a.
The method of claim 1,

The reference prediction signal is generated according to the intra prediction mode of the current block.
The method of claim 1,

Wherein the reference block is searched based on a template, wherein the template has a predetermined shape and is composed of pixels adjacent to the current block.
The method of claim 1,

The reference block is searched based on the location information,

The location information is extracted from the video signal.
The method of claim 1, wherein

Extracting flag information indicating whether a residual signal exists from the video signal;

And when the residual signal exists according to the flag information.
In a method of encoding a video signal,

Searching for a reference block for the current block, wherein the reference block is already reconstructed in the current frame;

Generating a reference residual signal of the reference block;

Generating a prediction signal of the current block according to an intra prediction mode of the current block;

Updating the prediction signal of the current block by adding the reference residual signal to the prediction signal of the current block; And

Generating a residual signal of the current block based on the updated prediction signal

Method comprising a.
The method of claim 6, wherein the method is

Generating a reference prediction signal representing a prediction value for the searched reference block,

The reference prediction signal is generated according to the intra prediction mode of the current block.
The method of claim 6,

Wherein the reference block is searched based on a template, wherein the template has a predetermined shape and is composed of pixels adjacent to the current block.
The method of claim 6, wherein the method is

Encoding position information of the reference block; And

Transmitting position information of the reference block

Method further comprising a.
The method of claim 6, wherein the method is

Performing transformation on the residual signal of the current block;

Performing quantization on the converted residual signal; And

Performing entropy encoding on the quantized residual signal

Method further comprising a.
An apparatus for decoding a video signal,

Generating a reference residual signal by searching for a reference block for a current block, generating a reference prediction signal representing a prediction value for the searched reference block, and subtracting the reference prediction signal from the reference block part;

A residual signal compensator configured to compensate the residual signal of the current block obtained from the video signal based on the reference residual signal; And

A reconstruction unit reconstructing the current block by adding the compensated residual signal and the prediction signal of the current block

Including,

And the reference block has already been restored in the current frame.
The method of claim 11,

And the reference prediction signal is generated according to an intra prediction mode of the current block.
An apparatus for encoding a video signal,

Search a reference block for a current block, generate a reference residual signal of the reference block, generate a prediction signal of the current block according to an intra prediction mode of the current block, and reference the prediction signal of the current block A prediction unit for updating a prediction signal of the current block by adding a residual signal; And

A residual signal obtaining unit generating a residual signal of the current block based on the updated prediction signal.

Apparatus comprising a.
The method of claim 13, wherein the prediction unit,

And generate a reference prediction signal representing a prediction value for the searched reference block, wherein the reference prediction signal is generated according to an intra prediction mode of the current block.
The method of claim 13, wherein the device,

A transformer for transforming the residual signal of the current block;

A quantization unit performing quantization on the converted residual signal; And

An entropy encoding unit that performs entropy encoding on the quantized residual signal

Apparatus further comprising a.