KR20200085236A - Efficient prediction and transform encoding/decoding method and apparatus - Google Patents

Abstract

An image encoding/decoding method and device according to the present invention determine a prediction block of a current block belonging to a current picture by using a pre-restored area in the current picture and restore the transform block of the current block, and the current block can be restored based on the prediction block and the transform block.

Description

Efficient prediction and transform encoding/decoding method and apparatus{EFFICIENT PREDICTION AND TRANSFORM ENCODING/DECODING METHOD AND APPARATUS}

The present invention relates to an image encoding/decoding method and apparatus, and more particularly, to a method and apparatus for more efficiently predicting a current block using reconstruction information in a current picture, and encoding/decoding a transform coefficient accordingly. .

Recently, the demand for multimedia data such as video has been rapidly increasing on the Internet. However, the speed at which the bandwidth of the channel develops is difficult to keep up with the rapidly increasing amount of multimedia data. Accordingly, the International Standardization Organization's Video Coding Expert Group (VCEG) of the ITU-T and the Moving Picture Expert Group (MPEG) of the ISO/IEC announced the High Efficiency Video Coding (HEVC) version 1, the video compression standard, in February 2014. Instituted.

HEVC defines techniques such as intra-picture prediction (or intra prediction), inter-picture prediction (or inter prediction), transformation, quantization, entropy encoding, and in-loop filters.

The present invention is to provide a method and apparatus for more efficiently predicting a current block using reconstruction information in a current picture.

The present invention is to provide a method and apparatus for encoding/decoding a transform coefficient of a current block.

The video encoding/decoding method and apparatus according to the present invention uses a pre-restored region in a current picture to determine a prediction block of a current block belonging to the current picture, and encode/decode a transform block of the current block, , The current block may be reconstructed based on the prediction block and the transform block.

In the image encoding/decoding method and apparatus according to the present invention, the determining of the prediction block may include determining a candidate for deriving motion information of the current block, and a candidate list of the current block based on the candidate And determining motion information of the current block from the candidate list.

In the image encoding/decoding method and apparatus according to the present invention, the candidate may refer to motion information of neighboring blocks spatially adjacent to the current block.

In the image encoding/decoding method and apparatus according to the present invention, the prediction block may be limited to belong to the same coding tree unit (CTU) or CTU row as the current block.

In the image encoding/decoding method and apparatus according to the present invention, motion information of the neighboring block may be selectively added to the candidate list based on whether the size of the current block is greater than a predetermined threshold size.

In the image encoding/decoding method and apparatus according to the present invention, the candidate list may further include motion information stored in a buffer of the encoding/decoding apparatus.

In the image encoding/decoding method and apparatus according to the present invention, the current block is divided into a plurality of sub-blocks, and encoding/decoding the transform block encodes sub-block information for the sub-block of the current block. According to the step of /decoding and the sub-block information, if there is at least one non-zero coefficient in the sub-block, 0 or more coefficient information, 1 or more coefficient information, Parity information or 3 for the current coefficient in the sub-block And encoding/decoding at least one of the excess coefficient information.

In the image encoding/decoding method and apparatus according to the present invention, the number information for the sub-block is encoded/decoded, and the number information may mean the maximum number of coefficient information allowed for the sub-block.

In the image encoding/decoding method and apparatus according to the present invention, the coefficient information may include at least one of the 0 excess coefficient information, the 1 excess coefficient information, the parity information, or the 3 excess coefficient information.

In the video encoding/decoding method and apparatus according to the present invention, the number information is each time at least one of the zero excess coefficient information, the one excess coefficient information, the parity information, or the three excess coefficient information is respectively encoded/decoded. It can be increased/decreased by 1.

In the present invention, it is possible to improve the accuracy of a prediction signal by searching for motion information of a block within a current picture rather than a previous reconstructed picture, and to provide an image encoding/decoding method and apparatus for more efficiently transmitting transform coefficients accordingly.

1 is a block diagram showing an image encoding apparatus.
2 is a block diagram showing an intra prediction unit of the video encoding apparatus.
3 is a block diagram illustrating an inter-screen prediction unit of the video encoding apparatus.
4 is a method of encoding prediction mode information.
5 is a block diagram showing the image decoding apparatus 200.
6 shows an in-screen prediction unit of the video decoding apparatus.
7 shows an inter-screen prediction unit of the video decoding apparatus.
8 is a method of decoding prediction mode information.
9 is a flowchart illustrating a method of encoding a transform block.
10 is a flowchart illustrating a method of decoding a transform block.
11 is a flowchart illustrating a context adaptive binary arithmetic coding method.
12 is a flowchart illustrating a context-adaptive binary arithmetic decoding method.
13 is a diagram illustrating an example in which probability information is differently applied according to information of neighboring coefficients.
14 is a diagram illustrating an example in which probability information is differently applied according to information of neighboring coefficients.
15 is a block diagram illustrating an image encoding apparatus according to an embodiment of the present invention.
16 illustrates a method of generating a prediction block using block copy prediction in a screen according to an embodiment of the present invention.
17 illustrates a method of generating a prediction block using block copy prediction in a screen according to an embodiment of the present invention.
18 illustrates a method of generating a prediction block using block copy prediction in a screen according to an embodiment of the present invention.
19 illustrates a method of generating a prediction block using block copy prediction in a screen according to an embodiment of the present invention.
20 illustrates a method of generating a prediction block using block copy prediction in a screen according to an embodiment of the present invention.
21 illustrates a method of generating a prediction block using block copy prediction in a screen according to an embodiment of the present invention.
22 illustrates a method of generating a prediction block using block copy prediction in a screen according to an embodiment of the present invention.
23 illustrates a method of generating a prediction block using intra-screen block copy prediction according to an embodiment of the present invention.
24 is a block diagram illustrating an in-screen block copy prediction unit of an image encoding apparatus according to an embodiment of the present invention.
25 shows the positions of spatial candidates adjacent to the current block.
26 is a method of encoding prediction mode information according to an embodiment of the present invention.
27 is a block diagram illustrating an in-screen block copy prediction unit of an image decoding apparatus according to an embodiment of the present invention.
28 is a block diagram illustrating an in-screen block copy prediction unit of an image decoding apparatus according to an embodiment of the present invention.
29 is a method of decoding prediction mode information according to an embodiment of the present invention.
30 is a flowchart illustrating a method of encoding quantized transform coefficients according to an embodiment of the present invention.
31 is a flowchart illustrating a method of decoding a quantized transform coefficient according to an embodiment of the present invention.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention pertains may easily practice the present invention with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are assigned to similar parts throughout the specification.

Throughout this specification, when a part is said to be'connected' to another part, this includes not only the case of being directly connected, but also the case of being electrically connected with another element in between.

In addition, when it is said that a part "includes" a certain component in the whole specification, it means that other components may be further included rather than excluding other components unless otherwise specified.

Further, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components.

In addition, in the embodiments of the apparatus and method described herein, a part of the configuration of the apparatus or a part of the method may be omitted. Also, the order of some of the components of the device or some of the steps of the method may be changed. In addition, other configurations or other steps may be inserted in some of the configuration of the device or in some of the steps of the method.

Further, some of the components or steps of the first embodiment of the present invention may be added to the second embodiment of the present invention, or may replace some components or steps of the second embodiment.

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

In the present specification, blocks may be variously expressed in units, regions, units, partitions, and the like, and samples may be variously expressed in pixels, pels, pixels, and the like.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, redundant description of the same components will be omitted.

1 is a block diagram showing an image encoding apparatus. Referring to FIG. 1, the image encoding apparatus 100 includes a block division unit S101, an intra prediction unit S102, an inter prediction unit S103, a subtraction unit S104, a transformation unit S105, and a quantization unit. (S106), an entropy encoding unit (S107), an inverse quantization unit (S108), an inverse transformation unit (S109), a multiplication unit (S110), a filter unit (S111), and a memory (S112).

RD-Cost (RateDistortion-Cost) is compared to select the optimal information from each device. RD-Cost means a cost value calculated by using distortion information between an original block and a reconstructed block and a bit amount generated during prediction mode transmission. In this case, SAD (Sum of Absolute Difference), SATD (Sum of Absolute Transformed Difference), and SSE (Sum of Square for Error) may be used to calculate the cost value.

Each component shown in FIG. 1 is independently illustrated to represent different characteristic functions in the image encoding apparatus, and does not mean that each component is composed of separate hardware or one software component unit. That is, for convenience of description, each component is listed and included as each component, and at least two components of each component are combined to form one component, or one component is divided into a plurality of components to perform functions. The integrated and separated embodiments of the components are also included in the scope of the present invention without departing from the essence of the present invention.

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

The block division unit 100 may divide the input image into at least one block. At this time, the input image may have various shapes and sizes such as pictures, slices, tiles, segments, and CTUs. The block may mean a coding unit (CU), a prediction unit (PU), or a transformation unit (TU). The splitting may be performed based on at least one of a quadtree, a binary tree, and a ternary tree. Quad tree divides the upper block into lower blocks whose width and height are half of the upper block. The binary tree is a method of dividing the upper block into lower blocks, which are either half or higher of the upper block. The ternary tree is a method in which either the upper block is divided into upper blocks or lower blocks by either height or width. Through partitioning based on the binary tree and ternary tree described above, the block may have a square shape as well as a square shape.

The prediction units 102 and 103 may include an inter-screen prediction unit 103 performing inter-screen prediction prediction and an intra-screen prediction unit 102 performing intra-screen prediction prediction. It is possible to determine whether to use inter prediction prediction or intra prediction prediction for the prediction unit, and determine specific information (eg, prediction prediction mode, motion vector, reference picture, etc.) according to each prediction method. have. At this time, the processing unit for which prediction is performed and the processing unit for which the prediction method and specific content are determined may be different. For example, a method of prediction and a prediction mode are determined in a prediction unit, and prediction may be performed in a transformation unit.

The residual value (residual block) between the generated prediction block and the original block may be input to the transform unit 105. In addition, prediction mode information, motion vector information, and the like used for prediction may be encoded by the entropy encoding unit 107 together with the residual value and transmitted to the decoder. When a specific encoding mode is used, it is also possible to encode the original block as it is and transmit it to the decoding unit without generating a prediction block through the prediction units 102 and 103.

The intra prediction unit 102 may generate a prediction block based on reference pixel information around a current block, which is pixel information in a current picture. When the prediction mode of the neighboring block of the current block to which the intra prediction is to be performed is inter prediction prediction, the reference pixel included in the neighboring block to which the inter prediction prediction is applied is referred to as a reference pixel in another block around the intra prediction is applied. Can be replaced. That is, when the reference pixel is not available, the available reference pixel information may be replaced with at least one reference pixel among the available reference pixels.

In the intra prediction, the prediction mode may have a directional prediction mode that uses reference pixel information according to a prediction direction and a non-directional mode that does not use directional information when performing prediction. The mode for predicting the luminance information and the mode for predicting the color difference information may be different, and the prediction prediction mode information or the predicted luminance signal information used in the screen used to predict the luminance information may be used to predict the color difference information. have.

The intra prediction unit 102 may include an adaptive intra smoothing (AIS) filter, a reference pixel interpolation unit, and a DC filter. The AIS filter is a filter that performs filtering on the reference pixel of the current block and can adaptively determine whether to apply the filter according to the prediction mode of the current prediction unit. When the prediction mode of the current block is a mode that does not perform AIS filtering, the AIS filter may not be applied.

The reference pixel interpolation unit of the intra-screen prediction unit 102 is a fractional unit by interpolating the reference pixels when the intra-prediction prediction mode of the prediction unit is a prediction unit that performs intra-prediction prediction based on pixel values interpolated with reference pixels. A reference pixel at a position can be generated. If the prediction mode of the current prediction unit is a prediction mode in which a prediction block is generated without interpolating a reference pixel, the reference pixel may not be interpolated. The DC filter may generate a prediction block through filtering when the prediction mode of the current block is the DC mode.

The inter-screen prediction unit 103 generates a prediction block using the pre-restored reference image and motion information stored in the memory 112. The motion information may include, for example, a motion vector, a reference picture index, a list 1 prediction flag, a list 0 prediction flag, and the like.

The inter-screen prediction unit 103 may derive a prediction block based on information of at least one of a previous picture or a subsequent picture of the current picture. In addition, a prediction block of a current block may be derived based on information of some regions in which encoding in a current picture is completed. The inter-screen prediction unit 103 according to an embodiment of the present invention may include a reference picture interpolation unit, a motion prediction unit, and a motion compensation unit.

The reference picture interpolator may receive reference picture information from the memory 112 and generate pixel information of an integer pixel or less in the reference picture. In the case of luminance pixels, a DCT-based 8-tap interpolation filter (DCT-based interpolation filter) having different filter coefficients may be used to generate pixel information of integer pixels or less in units of 1/4 pixels. For the color difference signal, a DCT-based interpolation filter (DCT-based interpolation filter) having different filter coefficients may be used to generate pixel information of an integer pixel or less in units of 1/8 pixels.

The motion prediction unit may perform motion prediction based on the reference picture interpolated by the reference picture interpolation unit. As a method for calculating the motion vector, various methods such as Full Search-based Block Matching Algorithm (FBMA), Three Step Search (TSS), and New Three-Step Search Algorithm (NTS) can be used. The motion vector may have a motion vector value in units of 1/2 or 1/4 pixels based on the interpolated pixels. The motion prediction unit may predict a prediction block of a current block by differently using a motion prediction method. As a motion prediction method, various methods such as a skip method, a merge method, and an advanced motion vector prediction (AMVP) method may be used.

The subtraction unit S104 subtracts the prediction block generated by the current encoding block and the intra prediction unit S102 or the inter prediction unit S103 to generate a residual block of the current block. The generated residual block may be input to the conversion unit S103 and converted.

The transform unit S105 may transform the residual block including the residual data using a transform method such as DCT, DST, or Karhunen Loeve Transform (KLT). At this time, the transform method may be determined based on the intra prediction mode of the prediction unit used to generate the residual block. For example, according to the intra prediction mode, DCT may be used in the horizontal direction and DST may be used in the vertical direction.

The quantization unit S106 may quantize the values converted from the conversion unit S105 into the frequency domain. The quantization coefficient may vary depending on the block or the importance of the image. The value calculated by the quantization unit S106 may be provided to the inverse quantization unit S108 and the entropy encoding unit S107.

The transformation unit S105 and/or the quantization unit S106 may be selectively included in the image encoding apparatus 100. That is, the image encoding apparatus 100 may encode the residual block by performing at least one of transformation or quantization on the residual data of the residual block, or skipping both transformation and quantization. Even if neither the transformation nor the quantization is performed in the image encoding apparatus S100, or both the transformation and quantization are performed, the block entering the input of the entropy encoding unit S107 is generally referred to as a transformation block. The entropy encoding unit S107 entropy-encodes the input data. Entropy encoding may use various encoding methods, such as exponential Golomb, CAVLC (Context-Adaptive Variable Length Coding), and CABAC (Context-Adaptive Binary Arithmetic Coding).

The entropy encoding unit S107 includes a variety of transform block coefficient information, block type information, prediction mode information, split unit information, prediction unit information, transmission unit information, motion vector information, reference frame information, block interpolation information, and filtering information. Information can be encoded. Coefficients of the transform block may be coded in units of sub-blocks in the transform block.

For encoding of the coefficients of the transform block, Last_sig, which is a syntax element indicating the position of the first non-zero coefficient in reverse scan order, and Coded_sub_blk_flag, which is a flag indicating whether there is at least one non-zero coefficient in the subblock, Sig_coeff_flag, a flag indicating whether the coefficient is non-zero, Abs_greater1_flag, a flag indicating whether the absolute value of the coefficient is greater than 1, Abs_greater2_flag, a flag indicating whether the absolute value of the coefficient is greater than 2, and Sign_flag, a flag indicating the sign of the coefficient, etc. Syntax elements can be coded. The residual value of the coefficient that is not encoded by the syntax elements alone may be encoded through the syntax element remaining_coeff.

The inverse quantization unit S108 and the inverse transformation unit S109 inverse quantize the values quantized by the quantization unit S106 and inversely transform the values converted by the transformation unit S105. The residual values generated by the inverse quantization unit S108 and the inverse transformation unit S109 are predicted by the motion estimation unit included in the prediction units S102 and 103, the motion compensation unit, and the intra prediction unit S102. It can be combined with the prediction unit to generate a reconstructed block. The estimator S110 generates a reconstructed block by incrementing the prediction block generated by the prediction units S102 and S103 and the residual block generated by the inverse transform unit S109.

The filter unit S111 may include at least one of a deblocking filter, an offset correction unit, and an adaptive loop filter (ALF).

The deblocking filter can remove block distortion caused by boundary between blocks in the reconstructed picture. In order to determine whether to perform deblocking, it may be determined whether to apply a deblocking filter to the current block based on pixels included in a few columns or rows included in the block. When a deblocking filter is applied to a block, a strong filter or a weak filter may be applied according to the required deblocking filtering strength. In addition, in applying the deblocking filter, when performing vertical filtering and horizontal filtering, horizontal filtering and vertical filtering may be processed in parallel.

The offset correction unit may correct an offset from the original image in units of pixels for the deblocking image. In order to perform offset correction for a specific picture, after dividing the pixels included in the image into a certain number of regions, determining the region to perform the offset and applying the offset to the region, or offset by considering the edge information of each pixel You can use the method of applying.

ALF (Adaptive Loop Filtering) may be performed based on a value obtained by comparing a filtered reconstructed image with an original image. After dividing the pixels included in the image into a predetermined group, one filter to be applied to the group may be determined to perform filtering differently for each group. For information related to whether to apply ALF, the luminance signal may be transmitted for each coding unit (CU), and the shape and filter coefficient of the ALF filter to be applied may be changed according to each block. Also, the ALF filter of the same form (fixed form) may be applied regardless of the characteristics of the block to be applied.

The memory S112 may store the reconstructed block or picture calculated through the filter unit S111, and the stored reconstructed block or picture may be provided to the predictors S102 and S103 when performing inter-frame prediction.

2 is a block diagram showing an intra prediction unit of the video encoding apparatus.

After intra prediction is selected for the prediction mode of the current block, the reference pixel generation unit S201 performs reference pixel derivation and reference pixel filtering around the current block. The reference pixel is determined using a reconstructed pixel around the current block. If some reconstructed pixels are not available around the current block or there are no reconstructed pixels, padding may be performed in an area where the available reference pixels are not available, or padding may be performed with an intermediate value among a range of values the pixels may have. After deriving all the reference pixels, filtering is performed using an adaptive intra smoothing (AIS) filter.

The optimum intra prediction mode determination unit is an apparatus for determining one prediction mode among the M intra prediction modes (S202). Here, M represents the total number of prediction modes in the screen. The intra prediction mode generates a prediction block generated using a reference pixel filtered according to a directional prediction mode and a non-directional prediction mode. RD-Cost is compared for each prediction mode within the screen to select one prediction mode with the lowest cost value.

3 is a block diagram showing in detail a prediction unit between screens of an image encoding apparatus.

The inter-screen prediction unit may be divided into a Merge candidate search unit (S302) and an AMVP candidate search unit (S304) according to a method for deriving motion information. The Merge candidate search unit S302 sets a reference block in which inter-frame prediction is used among blocks reconstructed around the current block as a Merge candidate. The Merge candidate is derived in the same way from the encoding/decoding device, the same number is used, and the number of Merge candidates is transmitted from the encoding device to the decoding device. At this time, if the set number of Megre candidates is not set as a reference block restored around the current block, motion information of a block existing in the same position as the current block is obtained from a picture other than the current picture. Alternatively, a candidate for merge is set by combining past and future motion information based on the current picture as a candidate, or by setting a block at the same location of another reference picture as motion information.

The AMVP candidate search unit S304 determines motion information of the current block in the motion estimation unit S305. The motion estimation unit S305 finds a prediction block most similar to the current block among the reconstructed pictures.

The inter-screen prediction unit determines motion information of the current block using one of the Merge candidate search unit and the AMVP candidate search unit, and then generates a prediction block through motion compensation (S306).

4 is a method of encoding prediction mode information.

Skip mode operation information encoding (S401) is information that indicates whether prediction mode information of a current block is used as Merge information of inter-picture prediction, and whether a prediction block is used as a reconstruction block in a decoding device.

If the Skip mode operates, the determined Merge candidate index encoding (S403) is performed, and if it is not operated, the prediction mode encoding (S404) is performed.

Prediction mode encoding (S404) encodes whether the prediction mode of the current block is inter prediction or intra prediction. If the inter prediction mode is selected, Merge mode operation information is encoded (S406). If the Merge mode operates (S407), Merge candidate index encoding (S403) is performed. If the Merge mode does not operate, prediction direction encoding is performed (S408). The prediction direction encoding (S408) indicates whether the direction of the reference picture to be used is in the past direction, the future direction, or both directions based on the current picture. If the prediction direction is the past or bidirectional (S409), the past direction reference picture index information encoding (S410), the past direction MVD information encoding (S411), the past direction MVP information is encoded (S412), and the prediction direction is the future or bidirectional. In case (S413), the future direction reference picture index information encoding (S414), the future direction MVD information encoding (S415), and the future direction MVP information is encoded (S416), and prediction motion information between screens of the current block may be reported. The information encoded in the inter prediction process is referred to as inter prediction mode information encoding (40).

If the prediction mode is an intra prediction mode, MPM operation information is encoded (S417). MPM motion information encoding is information that informs us to use the same prediction mode information as the reconstructed block without encoding the prediction mode information of the current block when the current block has the same prediction mode information as the current block among the restored blocks around the current block. . When the MPM operation is performed (S418), the MPM index encoding (S419) is performed to inform which reconstructed block prediction mode is used as the prediction mode of the current block, and when the MPM operation is not performed (S418), the residual prediction mode encoding is performed. (S420). Residual prediction mode encoding encodes a prediction mode index used as a prediction mode of the current block among the remaining prediction modes, excluding the prediction mode selected as the MPM candidate. Information encoded in the intra prediction process is referred to as intra prediction mode information encoding (41).

Next, the video decoding apparatus of the present invention will be described with reference to the drawings. 5 is a block diagram showing an image decoding apparatus 200 of the present invention.

Referring to FIG. 5, the image decoding apparatus 500 includes an entropy decoding unit 501, an inverse quantization unit 502, an inverse transform unit 503, an increase unit 504, a filter unit 505, a memory 506, and Prediction units 507 and 508 may be included.

When the image bitstream generated by the image encoding apparatus 100 is input to the image decoding apparatus 500, the input bitstream may be decoded according to a process opposite to that performed by the image encoding apparatus 100. .

The entropy decoding unit 501 may perform entropy decoding in a procedure opposite to that performed by the entropy encoding in the entropy encoding unit 507 of the image encoding apparatus 100. For example, various methods such as Exponential Golomb (CAVLC), Context-Adaptive Variable Length Coding (CAVLC), and Context-Adaptive Binary Arithmetic Coding (CABAC) may be applied to the method performed in the image encoder. The entropy decoding unit 201 may decode syntax elements as described above, that is, Last_sig, Coded_sub_blk_flag, Sig_coeff_flag, Abs_greater1_flag, Abs_greater2_flag, Sign_flag, and remaining_coeff. Also, the entropy decoding unit 501 may decode information related to intra prediction prediction and inter prediction prediction performed by the image encoding apparatus 100.

The inverse quantization unit 502 performs inverse quantization on the quantized transform block to generate a transform block. It operates substantially the same as the inverse quantization unit 108 of FIG. 1.

The inverse transform unit 503 performs an inverse transform on the transform block to generate a residual block. In this case, the transform method may be determined based on information on a prediction method (inter-screen prediction or intra-screen prediction prediction), the size and/or shape of a block, and a prediction prediction mode within a screen. It operates substantially the same as the inverse transform unit 109 of FIG.

The estimating unit 504 generates a reconstructed block by incrementing the residual block generated by the inverse transform unit 503 and the prediction block generated by the intra prediction unit 507 or the inter prediction unit 508. It operates substantially the same as the increase unit 110 of FIG. 1.

The filter unit 505 reduces various kinds of noise generated in the reconstructed blocks.

The filter unit 505 may include a deblocking filter, an offset correction unit, and an ALF.

Information about whether a deblocking filter is applied to a corresponding block or picture and information about whether a strong filter is applied or a weak filter is applied may be provided from the video encoding apparatus 100. The deblocking filter of the image decoding apparatus 500 may receive information related to the deblocking filter provided by the image encoding apparatus 100 and perform deblocking filtering on the corresponding block in the image decoding apparatus 500.

The offset correction unit may perform offset correction on the reconstructed image based on the type of offset correction and offset value information applied to the image during encoding.

ALF may be applied to a coding unit based on ALF application information, ALF coefficient information, and the like provided from the image encoding apparatus 100. The ALF information may be provided by being included in a specific parameter set. The filter unit 505 operates substantially the same as the filter unit 111 of FIG. 1.

The memory 506 stores the reconstructed block generated by the incrementer 504. It operates substantially the same as the memory 112 of FIG. 1.

6 and 7 show an intra-prediction unit and an inter-prediction unit of the video decoding apparatus.

The intra prediction unit 600 is omitted from the process of determining the optimal prediction mode of FIG. 2, and the process of generating the prediction block by receiving the prediction mode determined to be optimal is substantially the same as the intra prediction unit of the video encoding apparatus. It works.

The inter-screen prediction unit 700 is missing only the process of determining the optimal prediction mode of FIG. 3, and the process of generating the prediction block by receiving the prediction mode determined as optimal is substantially the same as the inter-screen prediction unit of the image encoding apparatus. It works.

8 is a method of decoding prediction mode information. The method operates substantially the same as the method of encoding the prediction mode information of FIG. 4.

9 is a flowchart illustrating a method of encoding a transform block. The encoding method of the transform block of FIG. 9 may be performed by the entropy encoding unit 107 of the image encoding apparatus 100.

First, when scanning transform coefficients according to an inverse scan order, the first non-zero coefficient is determined as a reference coefficient, and the position information Last_sig is encoded (S901).

A sub-block including a reference coefficient is selected (S902), and transform coefficient information in the corresponding sub-block is encoded. If the sub-block including the reference coefficient is not, the sub-block information is encoded before encoding the coefficient in the transform block (S903). The sub-block information Coded_sub_blk_flag is a flag indicating whether there is at least one non-zero coefficient in the current sub-block. Thereafter, non-zero coefficient information is encoded (S904). Here, the non-zero coefficient information Sig_coeff_flag indicates whether the value of each coefficient existing in the sub-block is 0 or not.

Then, the N excess coefficient information is encoded (S905). Here, the N excess coefficient information indicates whether an absolute value of each coefficient exceeds a value from 1 to N for all coefficients present in the sub-block. N uses an arbitrary predetermined value for encoding and decoding, but it is possible to encode the value of N to use the same value for encoding and decoding. The number of N excess coefficient information may use any preset value or may be differently used depending on the position of the reference coefficient. The N excess coefficient information is encoded for all or part of the coefficients in the sub-block, and may be sequentially encoded according to the scan order of each coefficient.

For example, when N is set to 3, it is coded whether or not the absolute value of each coefficient is greater than 1 for all non-zero coefficients (non-zero coefficients) in the sub-block. For this, the flag Abs_greater1_flag, which indicates whether the absolute value of the coefficient is greater than 1, is used. After that, it is coded whether or not the coefficient determined as a value greater than 1 is greater than 2 only. For this, the flag Abs_greater2_flag, which indicates whether the absolute value of the coefficient is greater than 2, is used. Finally, it is coded whether or not the coefficient is determined to be greater than 2 only if it is greater than 3. For this, the flag Abs_greater3_flag, which indicates whether the absolute value of the coefficient is greater than 3, may be used.

Or, for a non-zero coefficient in a sub-block, whether or not the absolute value of each coefficient is greater than 1 is coded. For this, the flag Abs_greater1_flag, which indicates whether the absolute value of the coefficient is greater than 1, is used. Thereafter, only the coefficient determined to be a value greater than 1 can be coded to determine whether the coefficient is an even number. For this, parity information indicating whether the coefficient is even or odd may be used. Furthermore, it is possible to code whether the absolute value of the coefficient is greater than 3. For this, the flag Abs_greater3_flag indicating whether the absolute value of the coefficient is greater than 3 may be used.

As described above, the N excess coefficient information may include at least one of Abs_greaterN_flag or a flag indicating whether it is even. Here, N may be 1, 2, 3, but is not limited thereto. N may be a natural number greater than 3, such as 4, 5, 6, 7, 8, 9, and the like.

Then, code information indicating whether it is negative or positive is coded for each coefficient determined to be non-zero (S906). Sign_flag can be used for sign information.

Then, only the coefficient determined to have an absolute value greater than N, the remaining value minus N is defined as residual coefficient information, and the residual value information remaining_coeff of this coefficient is encoded (S907). At this time, information encoding for each coefficient may be performed as a method of passing to the next coefficient after performing steps S904, S905, S906, and S907 for each coefficient. Alternatively, information on coefficients in a sub-block may be coded for each step at a time. For example, if there are 16 coefficients in a sub-block, S904 for each of the 16 coefficients is first coded, and all S905 processes are performed only for coefficients in S904 where the absolute value of the coefficient is determined to be non-zero. You can carry out the process. Thereafter, if it is impossible to express the absolute value of the current coefficient in step S905, step S907 may be performed. The absolute value of the non-zero coefficient may be derived by decoding at least one of Sig_coeff_flag, one or more Abs_greaterN_flag, Parity information, or residual value information.

After encoding coefficient information for the current sub-block, it is checked whether the next sub-block exists (S909). If the next sub-block exists, it moves to the next sub-block (S910) and encodes the sub-block information (S903). The corresponding sub-block information Coded_sub_blk_flag is checked (S908), and when it is determined that the value of Coded_sub_blk_flag is true, Sig_coeff_flag, which is non-zero coefficient information, is encoded. If the value of the corresponding sub-block information Coded_sub_blk_flag is false, it means that there is no coefficient to be encoded in the corresponding sub-block, so check whether the next sub-block exists. Alternatively, after moving to the next sub-block, if the corresponding sub-block is a sub-block located at the lowest frequency side, it is set to the same at the time of encoding and decoding as being true without encoding and decoding of sub-block information on the assumption that there will be a non-zero coefficient. It is also possible to do.

In FIG. 9, for convenience of description, code information encoding (S906) is described as a process following S905, but may exist between S904 and S905 or may perform S906 after S907.

10 is a flowchart illustrating a method of decoding a transform block. The transform block decoding method of FIG. 10 corresponds to the transform block coding method of FIG. 9. The decoding method of the transform block of FIG. 10 may be performed by the entropy decoding unit 501 of the image decoding apparatus 500 of FIG. 5.

For the encoded information, a context-adaptive binarization arithmetic process is performed through a binarization process. The context-adaptive binarization arithmetic process refers to a process of symbolizing coded information in a block and applying and encoding the probability of occurrence of symbols differently using probability information according to circumstances. In this example, for convenience of explanation, only symbols 0 and 1 are used, but the number of symbols may be N (N is a natural number of 2 or more).

Probability information refers to the probability of occurrence of 0 and 1 in binarized information. The probability of occurrence of the two information may be the same or different depending on the previously restored information. It is also possible to have M probability information according to the information. At this time, the M probability information may be made into a probability table.

11 is a flowchart illustrating a context adaptive binary arithmetic coding method. First, probability initialization is performed (S1101). Probability initialization is a process of dividing the binarized intervals into the probability set in the probability information. However, what kind of probability information to use may use the same condition according to a predetermined rule arbitrarily in the encoding device or the decoding device, or the probability information may be separately coded. The initial probability interval may be determined in the same manner in the encoding/decoding process according to a preset rule. Alternatively, the initial probability interval may be newly encoded and used. Alternatively, probability intervals and probability information of previously used coding parameters may be obtained without probability initialization.

When the binary information of the current coding parameter to be encoded is determined (S1102), the binarized information of the current coding parameter is encoded using the probability interval state up to the previous step of step S1102 in FIG. 13 and the previous probability information of the same coding parameter. (S1103). Then, probability information and probability intervals may be updated (S1104) for binary information to be encoded later. Then, when the coding parameter information to be encoded next exists (S1105), the next coding parameter information is shifted (S1106), and the above-described process is repeated. If the coding parameter information to be encoded next does not exist, this flow chart ends.

12 is a flowchart illustrating a context-adaptive binary arithmetic decoding method. Unlike the encoding device, the decoding device decodes the binary information of the coding parameter using the probability information and the interval (S1202), and then determines the information of the current coding parameter (S1203). In addition, since the decoding method of FIG. 12 corresponds to the encoding method of FIG. 11, a detailed description is omitted.

In steps S1103 and S1202 of Figs. 11 and 12 described above, coding is performed by selectively using optimal probability information among M probability information preset using information (or coding parameters) already restored around each coding parameter. Decryption may proceed.

For example, probability information of a coding parameter may use probability information having a high probability of generating information according to the size of a transform block.

Alternatively, probability information may be differently applied according to information of neighbor coefficients of a coefficient to be encoded or decoded, and probability information of information to be currently encoded or decoded may be selected using probability information of previously encoded or decoded information. .

13 and 14 are diagrams showing an example in which probability information is differently applied according to information of neighboring coefficients.

13 is an example of a probability information table used for encoding or decoding the Sig_coeff_flag information value of the current coefficient. If the number of coefficients having the same information value as the Sig_coeff_flag information value of the current coefficient among coefficients adjacent to the current encoding or decoding coefficient is 1, index 8 is assigned to the current coefficient. At this time, the probability of symbol 1, which is the Sig_coeff_flag binary information of the current coefficient, is 61%, and the probability of symbol 0 is 39%. If the number of neighbor coefficients having the same information value as the Sig_coeff_flag information value of the current coefficient is two, index 5 is allocated to the current coefficient, and the probability of symbol 1, which is the Sig_coeff_flag binary information of the current coefficient at this time, is 71% and symbol 0 The probability of is 29%. If the number of neighbor coefficients having the same information value as the Sig_coeff_flag information value of the current coefficient is 3, index 2 is allocated to the current coefficient, and the probability of symbol 1, which is the Sig_coeff_flag binary information of the current coefficient, is 87%, and the probability of symbol 0 is 13%. It becomes.

After the current coefficients are encoded or decoded using the probability information table shown in FIG. 13, probability information may be updated as shown in FIG.

On the other hand, in the case of the non-zero coefficient information Sig_coeff_flag, the closer to the low-frequency region, probability information having a higher probability of occurrence of the non-zero coefficient information Sig_coeff_flag may be used.

Then, the probability information of the N excess coefficient information is set to the probability information of the current N excess coefficient information by using the probability information of the previously encoded/decoded N excess coefficient information, or the N excess that is initially encoded/decoded in units of sub-blocks Probability information of coefficient information may be used as it is. As described above, the N excess coefficient information may include at least one of Abs_greater1_flag, Abs_greater2_flag, Abs_greater3_flag, ??, or Abs_greaterN_flag.

In addition, the sub-block information Coded_sub_blk_flag may use probability information of neighboring coded/decoded M sub-blocks, or may use probability information of the immediately coded/decoded sub-block.

FIG. 15 is a diagram in which an in-screen block copy prediction unit is added to the image encoding apparatus 100 of FIG. 1. The block copy prediction unit in the screen may generate a prediction block of a block to be currently encoded using a reconstructed region in a current picture.

16 to 21 are examples in which a prediction block is generated by an in-screen block copy prediction unit. In the figure, CB indicates a current block and PB indicates a prediction block.

The motion search range may be limited within the reconstructed area. For example, as shown in FIG. 16, the motion search range may be limited to only the reconstructed area in the current picture, and as shown in FIG. 17, if any part of the prediction block belongs to the reconstructed area, the motion search range may be set. Alternatively, as in the example of FIG. 18, a case in which the current block and the prediction block partially overlap may be set as a motion search range. The overlapping region may be padded using adjacent reconstructed pixels, but the overlapped regions may be predicted using the reconstructed pixels.

19 to 21 are examples illustrating a method of generating a prediction block when the prediction block and the current block overlap. A is a region in which the current block and the prediction block overlap, and B is adjacent reconstructed pixels used to predict A. The reconstructed pixels that can be used may vary depending on which direction the prediction block is in, for example, the upper left, upper, upper right, or left of the current block. At this time, region A may be predicted using M (M is an integer of 1 or more) intra prediction modes. M is the number of prediction modes of intra prediction that can be used in the current block. FIG. 22 is an exemplary diagram illustrating A region pixel prediction using a left top direction mode among M available modes of a reconstructed pixel line and an intra prediction mode in FIG. 19 that can be used for A region pixel prediction.

The motion vector of the current block may be used to indicate the reconstructed pixel line for deriving the reference pixel line of the current block, rather than the predicted block of the current block in the reconstructed region in the current picture as shown in FIG. 23. In-frame prediction may be performed using M prediction modes using a reference pixel line of a reconstructed region that is not adjacent to the current block, and a prediction mode generating an optimal prediction block may be selected. In this case, a prediction block may be generated by using an optimal reference pixel line and a prediction mode among W (W is an integer of 1 or more) reference pixels, and different prediction modes or the same prediction mode for each of the W reference pixel lines After generating the prediction blocks by using, weighted sum of the generated prediction blocks, an optimal prediction block may be generated.

Alternatively, the prediction blocks may be generated using the block copy prediction and the intra-prediction, respectively, and then weighted sum of the generated prediction blocks to generate an optimal prediction block, and prediction using the inter-block prediction and intra-frame prediction After generating each block, an optimal prediction block may be generated by weighting the generated prediction blocks.

Also, the reference pixel line may use only the reconstructed pixel at the top or the reconstructed pixel at the left. At this time, when the prediction block and the current block overlap, a prediction block may be generated using a reference pixel line used when generating the prediction block.

In the drawings of FIGS. 16 to 22, the motion search range is exemplified as the current picture, but may be limited to the CTU or CTU row to which the current block belongs, or to a neighboring CTU. For example, the prediction block PB indicated by the motion vector of the current block CB may be restricted to belong to the same CTU or CTU row as the current block.

24 is a detailed block diagram of an intra-screen block copy prediction unit of the video encoding apparatus, and the intra-block copy prediction (S2401) may be divided into a CPR_Merge candidate search unit (S2402) and a CPR_AMVP candidate search unit (S2404). The CPR_Merge candidate search unit S2402 may use the reconstructed blocks as a CPR_Merge candidate. The reconstructed block may be a block that is encoded/decoded through inter-frame prediction, or may be limited to a block that is encoded/decoded in an intra-block copy (IBC) mode among neighboring blocks. The maximum number of CPR_Merge candidates can be used in the same manner in the encoding/decoding device or transmitted in the upper header. Here, the maximum number may be 2, 3, 4, 5 or more. The upper header means upper header information including picture and block information such as a video parameter stage, a sequence parameter stage, a picture parameter stage, and a slice stage. The CPR_Merge candidate derivation method will be described with reference to FIG. 24.

25 shows spatial candidates adjacent to the current block. AL, A, AR, L, BL are the same picture as the current block and are the positions of the reconstructed blocks that can be used as CPR_Merge candidates. For example, when inter-frame prediction or intra-screen block copy prediction is used in the reconstructed blocks of the AL, A, AR, L, BL positions, it can be used as a CPR_Merge candidate. In the reconstruction block, L, A, AR, BL, AL order, or other order considered by various priorities may be determined. The spatially adjacent reconstructed block may be used as a CPR_Merge candidate only when the size of the current block is larger than a predetermined threshold size. The size of the current block can be expressed as the width of the block, the height, the sum of the width and height, the product of the width and height, and the minimum/maximum value of the width and height. For example, if the product of the width and height of the current block is greater than 16, the reconstructed block is used as a CPR_Merge candidate, otherwise, the reconstructed block may not be used as a CPR_Merge candidate.

If the maximum number of candidates is not filled in the CPR_Merge candidate list, motion information stored in the H buffer may be added to the CPR_Merge candidate list. The H buffer may store motion information of a block that has been encoded/decoded before the current block. Alternatively, if the maximum number of candidates is not filled in the CPR_Merge candidate list, when the block copy prediction technique in the reconstructed block existing in the same position as the current block in the previously reconstructed picture is used, the motion information of the reconstructed block is displayed. Can be added as a CPR_Merge candidate.

Or, if the number of CPR_MVP candidates added to date is less than the maximum number of candidates, a default vector candidate may be added. The default vector may mean a vector determined in the same manner by the encoding/decoding device. For example, if the default vectors are (0, 0), (-10, 0), (0, -10), (-15, 0), (0, -15), and two CPR_Merge candidates are insufficient, Two default vectors can be added to the CPR_Merge candidate list in order from the front. Thereafter, the RD-cost of each motion information is calculated in the CPR_Merge candidate list, and the most suitable motion information is determined in the RD-cost (S2403).

The CPR_AMVP candidate search unit S2404 may generate a prediction block within a motion search range, and then obtain at least one of a CPR_MVP candidate or CPR_MVD information using motion information of a neighboring block. The maximum number of CPR_MVP candidates may be used in the same manner in the encoding/decoding device or transmitted in an upper header. Here, the maximum number may be 2, 3, 4, 5 or more. The number of CPR_MVP information can be used in the same manner in the encoding/decoding device or transmitted in the upper header. The method of deriving the CPR_MVP candidate will be described with reference to FIG. 24. AL, A, AR, L, BL belong to the same picture as the current block and are the positions of the reconstructed blocks that can be used as CPR_MVP candidates. When inter-frame prediction or intra-block copy prediction is used in the reconstructed blocks of the AL, A, AR, L, and BL positions, it may be used as a CPR_MVP candidate. In the reconstruction block, L, A, AR, BL, AL order, or other order considered by various priorities may be determined. The spatially adjacent reconstructed block may be used as a CPR_MVP candidate only when the size of the current block is larger than a predetermined threshold size. The size of the current block can be expressed as the width of the block, the height, the sum of the width and height, the product of the width and height, and the minimum/maximum value of the width and height. For example, if the product of the width and height of the current block is greater than 16, the reconstructed block is used as a CPR_MVP candidate, otherwise, the reconstructed block may not be used as a CPR_MVP candidate.

If the maximum number of candidates is not filled in the CPR_MVP candidate list, motion information stored in the H buffer may be added to the CPR_MVP candidate list. The H buffer may store motion information of a block that has been encoded/decoded before the current block. Or, if the maximum number of candidates is not filled in the CPR_MVP candidate list, when the block copy prediction technique in the reconstructed block existing in the same position as the current block in the previously reconstructed picture is used, motion information of the reconstructed block is used. It can be added as a CPR_MVP candidate.

If the number of CPR_MVP candidates added up to now is less than the maximum number of candidates, a default vector may be added to the CPR_MVP candidate list. The CPR_MVD information may be CPR_MVD information, which is a difference between a motion information of a current block and motion information stored in a CPR_MVP candidate. For example, if the motion vector of the current block is (-14, -14) and the motion vector of the CPR_MVP candidate is (-13, -13), the CPR_MVD information is ((-14)-(-13), ( -14)-(-13)) It can be the difference value (1, 1). Alternatively, when the motion search range cannot overlap the current block and the prediction block, the motion vector may be expressed by Equations 1 and 2 according to the size of the current block.

In Equations 1 and 2, Curr_MV.x and Curr_MV.y are the x and y components of the current block motion vector. Curr_blk_width and Curr_blk_height may be determined by various values, such as horizontal or vertical size of the current block, 1/2 of horizontal size, or 1/2 of vertical size. MV is a motion vector of the current block finally derived. For example, if the motion vector of the current block is (-14, -14) and the size of the current block is (4, 4), the motion vector may be set to (-10, -10). The motion vector of the current block may be determined by subtracting only half the length and width of the current block from the motion vector of the current block. Thereafter, the RD-cost of each motion information is calculated in the CPR_MVP candidate list, and the most suitable motion information for the RD-cost is determined (S2405).

In the block copy prediction unit in the screen, motion information of the current block is determined using one of the CPR_Merge candidate search unit and the CPR_AMVP candidate search unit, and then a prediction block is generated through motion compensation (S2406).

26 is a method of encoding prediction mode information.

Skip mode operation information encoding (S2601) is information that indicates whether a prediction block is used as a reconstruction block in an encoding device.

The prediction mode encoding (S2602) may encode whether the prediction mode of the current block is inter prediction, intra prediction, or intra block prediction. When it is encoded by inter-screen prediction (S2603), inter-screen prediction unit mode information may be encoded (S2604). The inter-prediction mode information encoding (S2604) may perform the same function as the inter-prediction mode information encoding 40 of FIG. 4. When the prediction mode is encoded by intra-prediction (S2605), intra-prediction mode information may be encoded (S2606). The intra prediction mode information encoding may perform the same function as the intra prediction mode information encoding 41 of FIG. 4. When an intra-block prediction mode is selected, CPR_Merge mode operation information may be encoded (S2607). If the CPR_Merge mode operates (S2608), CPR_Merge candidate index encoding (S2609) may be performed. If the CPR_Merge mode does not operate, CPR_MVD information encoding (S2610) and CPR_MVP candidates may be encoded (S2611). If it is determined that the current block and the prediction block overlap using the CPR_MVP candidate and the CPR_MVD information, the prediction mode for the overlapping region may be additionally encoded. In addition, when intra prediction is performed by the example of FIG. 23, after CPR_Merge candidate encoding (S2609) and CPR_MVP candidate encoding (S2611), intra prediction mode information encoding (S2606) may be performed.

In this case, if there is no previously reconstructed picture that can be used in the current picture by setting the upper header, inter-prediction mode information may be omitted during prediction mode encoding (S2602 ).

Prediction mode information encoding may be performed using FIG. 4.

In-screen block copy prediction unit mode information may be represented as inter-screen prediction unit mode information. The current picture information may be displayed by adding the reference picture index information set in the inter-screen prediction information. For example, when the reference picture index exists from 0 to 4, 0 to 3 may mean a previously reconstructed picture, and 4 may refer to a current picture. In the case of Merge candidate index encoding (S403), when the past direction reference picture index information is the current picture while using the past direction information, an intra-screen block copy prediction technique may be performed, and in other cases, an inter-screen prediction technique may be performed. . In the case of AMVP mode information encoding, when the past direction is encoded (S408) and the past direction reference picture index information is encoded as the current picture (S410), the past direction MVD information (S411) and the past direction MVP candidate are predicted. (S412) is information for predicting block copy in the screen, and in other cases, it may be inter-screen prediction technology information. At this time, if there is no previously reconstructed picture available in the current picture by setting the upper header, prediction direction encoding (S408), past direction reference picture index information encoding (S410), and future direction reference picture index information encoding ( S414), future direction MVD information encoding (S415) and future direction MVP information encoding (S416) can be omitted, and if inter prediction is coded in the prediction mode encoding step, this is not inter prediction but is not inter prediction. Can mean

FIG. 27 is a diagram in which an in-screen block copy prediction unit S2609 is added to the image decoding apparatus 500 of FIG. 5.

28 illustrates an in-block block copy prediction unit of an image decoding apparatus.

The in-screen block copy prediction unit 2800 is missing the process of determining the optimal prediction mode of FIG. 24, and the process of generating the prediction block by receiving the prediction mode determined as optimal is the in-screen block copy prediction unit of the image encoding apparatus. It operates substantially the same as 2400.

29 is a method of decoding prediction mode information.

Skip mode operation information decoding (S2901) is information that indicates whether the decoding device uses a prediction block as a reconstruction block.

The prediction mode decoding (S2902) may decode whether the prediction mode of the current block is inter-screen prediction, intra-screen prediction, or intra-block copy prediction. When decoded by inter-screen prediction (S2903), inter-screen prediction unit mode information may be decoded (S2904). The inter-prediction mode information decoding (S2904) may perform the same function as the inter-prediction mode information decoding 80 of FIG. 8. When the prediction mode is decoded by intra-prediction (S2905), the intra-prediction mode information may be decoded (S2906). Decoding the intra prediction unit mode information may perform the same role as the intra prediction unit information decoding 81 of FIG. 8. When the block copy prediction mode in the screen is selected, CPR_Merge mode operation information may be decoded (S2907). If the CPR_Merge mode operates (S2908), CPR_Merge candidate index decoding (S2909) may be performed. If the CPR_Merge mode does not operate, CPR_MVD information decoding (S2910) and CPR_MVP candidates may be decoded (S2911). If it is determined that the current block and the prediction block overlap using the CPR_MVP candidate and the CPR_MVD information, the prediction mode for the overlapping region may be additionally decoded. In addition, when intra-prediction is performed by the example of FIG. 23, after CPR_Merge candidate decoding (S2909) and CPR_MVP candidate decoding (S2911), intra-screen prediction mode information decoding (S2906) may be performed.

In this case, if there is no previously reconstructed picture that can be used in the current picture by setting the upper header, inter-prediction mode information may be omitted during prediction mode decoding (S2902 ).

The prediction mode information may be decoded using FIG. 8.

In-screen block copy prediction unit mode information may be represented as inter-screen prediction unit mode information. The current picture information may be displayed by adding the reference picture index information set in the inter-screen prediction information. For example, when the reference picture index exists from 0 to 4, 0 to 3 may mean a previously reconstructed picture, and 4 may refer to a current picture. In the case of decoding the Merge candidate index (S803), if the past direction reference picture index information is the current picture while using the past direction information, an intra-screen block copy prediction technique may be performed, and in other cases, an inter-screen prediction technique may be performed. . In the case of decoding AMVP mode information, when the past direction is decoded (S808) and the past direction reference picture index information is decoded (S810) as the current picture, the past direction MVD information (S811) and the past direction MVP candidate are decoded. (S812) is information for predicting block copy in the screen, and in other cases, it may be inter-screen prediction technology information. At this time, if there is no previously restored reference picture available in the current picture by setting the upper header, prediction direction decoding (S808), past direction reference picture index information decoding (S810), and future direction reference picture index information decoding (S814), the future direction MVD information decoding (S815), the future direction MVP information decoding (S816) process can be omitted, and if the inter-screen prediction is decoded in the prediction mode decoding step, this is not inter-screen prediction, rather than intra-screen copy copy prediction Can mean

30 is a flowchart illustrating a method of encoding quantized transform coefficients (hereinafter, referred to as'transform coefficients'). It may be performed by the entropy encoding units 107 and 1507 of the image encoding apparatuses 100 and 1500.

First, when scanning transform coefficients according to an inverse scan order, the first non-zero coefficient may be determined as a reference coefficient, and the position information (Last_sig) may be encoded (S3001).

The sub-block including the reference coefficient may be selected (S3002), and transform coefficient information in the corresponding sub-block may be encoded. If the sub-block including the reference coefficient is not, the sub-block information may be encoded before encoding the coefficient in the transform block (S3003). The sub-block information Coded_sub_blk_flag is a flag indicating whether there is at least one non-zero transform coefficient in the current sub-block. Before encoding coefficient information in a sub-block, the number of first coded information and the number of second coded information may be initialized to zero. The first coded information is the number of 0-coefficient information (S3006), 1-coefficient coefficient information (S3006), and parity information (S3007). The second coded information is the number of coded coefficients (S3010) exceeding three. The first step coefficient information encoding refers to a step of encoding the zero excess coefficient information, one greater coefficient information, and parity information (S3006, S3007, S3008). Coding of the second step coefficient information is a step of encoding three or more coefficient information (S3010).

Thereafter, the transform coefficients to be currently encoded may be selected in an inverse scan order (S3004). PosL means the first position of the transform coefficient that is not encoded in the inverse scan order in the current sub-block by the first step coefficient information encoding process. After selecting a transform coefficient to be encoded first in a sub-block, it is possible to encode the zero-over-coefficient information (S3006) indicating whether the absolute value of the current transform coefficient exceeds 0. When it is determined that the current transform coefficient is not 0, information on the coefficient of excess 1 indicating whether the current transform coefficient exceeds the absolute value 1 may be encoded (S3007 ). Thereafter, if it is determined that the absolute value of the current transform coefficient is greater than 1 due to the coefficient information exceeding 1, the parity information is encoded (S3008) to inform the parity of the current transform coefficient. For example, parity information may indicate whether the absolute value of the current transform coefficient is even or odd.

At this time, the number of the first coded information is increased if the information of the 0 excess coefficient, the information of the 1 excess coefficient, and the parity information are encoded (S3006, S3007, S3008). For example, when at least one of the coefficient information exceeding 0, the coefficient exceeding 1, or the parity information is encoded, the number of the first encoded information may be increased by 1. Alternatively, the number of first coded information may be increased by 1 whenever at least one of the coefficient information exceeding 0, the coefficient exceeding 1, or the parity information is respectively coded.

In other words, the number of first coded information may mean the maximum number of coefficient information allowed for one block. Here, the block may mean a transform block or a sub-block of the transform block. In addition, the coefficient information may include at least one of coefficient information exceeding 0, coefficient information exceeding 1, or parity information. The number of first coded information may be defined in units of a video sequence, picture, slice, coding tree block (CTU), coding block (CU), transform block (TU), or subblock of the transform block. That is, the same number of first coded information may be determined/set for all transform blocks or sub-blocks belonging to the corresponding unit.

After that, the PosL value is decreased by 1 to change the transform coefficient to be encoded into the next coefficient. At this time, if the number of the first coded information exceeds the first threshold value, or if the first step coefficient information encoding in the current sub-block is completed, it may be skipped to the step 3 coefficient information encoding. Otherwise, the next coefficient information can be encoded. The first threshold is a maximum number of at least one of 0 excess coefficient information, 1 excess coefficient information, and parity information that can be coded in units of sub-blocks (S3006, S3007, and S3008).

Only the transform coefficients in which the parity information is coded in the reverse scan order can be encoded with over 3 coefficient information (S3010). When the excess coefficient information is encoded, the number of second coded information may be increased. When the number of the second coded information exceeds the second threshold value or when the coefficient information encoding of the second step of the current sub-block is completed, the next step may be passed (S3011). The second threshold value is a maximum number of 3 or more coefficient information that can be coded in units of sub-blocks.

Alternatively, the first coded information may mean the maximum number of coefficient information that can be coded in a predetermined unit. The count information may include at least one of 0 count coefficient information, 1 time count information, Parity information, or 3 time count information. In this case, the step of encoding the coefficient information exceeding 3 may be included in the step of encoding the coefficient information.

Specifically, it is possible to encode the information of the excess zero coefficient indicating whether the absolute value of the current transform coefficient exceeds zero. If it is determined that the current transform coefficient is not 0, it is possible to encode over 1 coefficient information indicating whether the current transform coefficient exceeds the absolute value 1. Thereafter, if it is determined that the absolute value of the current transform coefficient is greater than 1 due to the information on the coefficient exceeding 1, parity information may be encoded and information on coefficient 3 exceeding may be encoded.

At this time, if the 0 excess coefficient information, the 1 excess coefficient information, the parity information, and the 3 excess coefficient information are encoded, the number of first coded information is increased. For example, if at least one of the 0 excess coefficient information, the 1 excess coefficient information, the parity information, or the 3 excess coefficient information is encoded, the number of first coded information may be increased by 1. Alternatively, the number of first coded information may be increased by 1 whenever at least one of the 0 excess coefficient information, 1 excess coefficient information, Parity information, or 3 excess coefficient information is respectively coded.

In other words, the number of first coded information may mean the maximum number of coefficient information allowed for one block. Here, the block may mean a transform block or a sub-block of the transform block. In addition, the coefficient information may include at least one of 0 excess coefficient information, 1 excess coefficient information, Parity information, or 3 excess coefficient information. The number of first coded information may be defined in units of a video sequence, picture, slice, coding tree block (CTU), coding block (CU), transform block (TU), or subblock of the transform block. That is, the same number of first coded information may be determined/set for all transform blocks or sub-blocks belonging to the corresponding unit.

PosC means the position of a transform coefficient to be currently coded. When PosL is smaller than PosC (S3012), it can be seen that the first step coefficient information is encoded. After encoding the N excess coefficient information, the minimum absolute value of the current transform coefficient, which can be known as the parity information of the current transform coefficient, is subtracted from the current coefficient value, and then the absolute value of the difference coefficient can be encoded (S3013). Here, N represents a number of 3 or more, and the same value can be used in the encoding/decoding device or transmitted in an upper header. When the N value is 5, information on coefficients exceeding 4 may be encoded for coefficients determined that the absolute value of the current coefficient is 4 or more. If it is determined that the absolute value of the current coefficient is 5 or more based on the 4 excess coefficient information, the 5 excess coefficient information may be encoded. If the value of the current transform coefficient is completely encoded by encoding the N excess coefficient information, the step of encoding the absolute value of the difference coefficient may be omitted (S3013). When PosL is larger than PosC, the absolute value of the current transform coefficient itself may be encoded (S3014). Subsequently, sine information encoding indicating the sign information of the current transform coefficient may be performed (S3015). If all the information about the current transform coefficients is encoded, the next transform coefficient in the sub-block can be selected as the current transform coefficient by reducing the PosC value by 1 (S3017), and if the current transform coefficient is the last transform coefficient in the sub-block, the first threshold The value and the second threshold may be updated (S3018).

The first and second threshold values may be adjusted when the number of transform coefficients in which the absolute values of the current coefficients themselves are encoded in the current sub-block is C (C is an integer of 0 or more). For example, if the first threshold value is 13, the first coded information number is 15, the second threshold value is 2, and the second coded information number is 2, the first and second coded information are first. In this case, since the second threshold value is reached, the first and second threshold values can be updated. In addition, for example, if the first threshold is 13, the first coded information number is 15, the second threshold value is 2, and the second coded information number is 1, the first coded information is the first threshold value. However, since the second threshold has not reached the second coded information, the first threshold value may be increased and the second threshold value may be updated in a direction of decreasing. Alternatively, if the first and second coded information do not reach both the first and second threshold values, the first and second threshold values may be updated to decrease the first and second threshold values. Alternatively, updates may also be performed in a direction to maintain the first and second threshold values.

If the current sub-block is not the last sub-block (S3019), it moves to the next sub-block (S3020), and if it is the last sub-block (S3019), encoding of the transform block may be ended.

31 is a flowchart illustrating a method of decoding a quantized transform coefficient. It may be performed by the entropy decoding units 501 and 2601 of the image decoding devices 500 and 2600.

First, when decoding transform coefficients according to an inverse scan order by decoding Last_sig, the first non-zero coefficient may be determined as a reference coefficient (S3101).

The sub-block including the reference coefficient may be selected (S3102), and transform coefficient information in the corresponding sub-block may be decoded. If the sub-block including the reference coefficient is not, the sub-block information may be decoded before decoding the coefficient in the transform block (S3103). The sub-block information Coded_sub_blk_flag is a flag indicating whether there is at least one non-zero coefficient in the current sub-block. Before decoding the coefficient information in the sub-block, the number of first decoded information and the number of second decoded information may be initialized to zero. The first decoded information is the number of the 0-coefficient information (S3106), the 1-coefficient coefficient information (S3106), and the parity information (S3107). The second decoded information is the number of 3 over-coefficient information S3110 decoded.

Thereafter, the transform coefficients to be currently decoded can be selected in an inverse scan order (S3104). PosL means the first position of the transform coefficient that is not decoded in the inverse scan order in the current sub-block by the first step coefficient information decoding process. After selecting a transform coefficient to be decoded first in a sub-block, it is possible to decode the zero-over-coefficient information (S3106) indicating whether the absolute value of the current transform coefficient exceeds 0. If it is determined that the current transform coefficient is not 0, it is possible to decode the excess 1 coefficient information indicating whether the current transform coefficient exceeds the absolute value 1 (S3107). Thereafter, when it is determined that the absolute value of the current transform coefficient is greater than 1 due to the coefficient information exceeding 1, the parity information may be decoded (S3108) to know the parity of the current transform coefficient. At this time, if the zero exceeded coefficient information, the first excess coefficient information, and the parity information are decoded, the number of the first decoded information is reduced (S3106, S3107, S3108). For example, if at least one of the coefficient information exceeding 0, information exceeding 1, or parity information is decoded, the number of first decoded information may be reduced by 1. Alternatively, the number of the first decoded information may be reduced by 1 whenever at least one of the over 0 coefficient information, the over 1 coefficient information, or the parity information is respectively decoded. That is, the number of first decoded information may mean the maximum number of coefficient information transmitted for one block. Here, the block may mean a transform block or a sub-block of the transform block. In addition, the coefficient information may include at least one of 0 or more coefficient information, 1 or more coefficient information, or parity information. The number of first decoded information may be defined in units of a video sequence, picture, slice, coding tree block (CTU), coding block (CU), transform block (TU), or sub block of the transform block. That is, the same number of first decoded information may be set for all transform blocks or sub-blocks belonging to the corresponding unit.

Thereafter, the PosL value is decreased by 1 to convert the coefficient to be decoded into the next transform coefficient. At this time, if the number of the first decoded information exceeds the first threshold value or decoding of the first step coefficient information in the current sub-block is completed, it may be skipped to a step of decoding the third-order coefficient information. Otherwise, the next transform coefficient information can be decoded. The first threshold value is the maximum number of 0 excess coefficient information, 1 excess coefficient information, and parity information that can be decoded in units of sub-blocks (S3106, S3107, S3108). The first step coefficient information refers to a step of decoding the 0 excess coefficient information, the 1 excess coefficient information, and the parity information (S3106, S3107, S3108).

Only the transform coefficients in which the parity information is decoded in the inverse scan order can decode the over 3 coefficient information (S3110). When decoding the excess coefficient information, the number of second decoded information may be increased. When the number of the second decoded information exceeds the second threshold or decoding of the coefficient information in the second step of the current sub-block is completed, the next step may be passed (S3111). The second threshold is the maximum number of over 3 coefficient information that can be decoded in sub-block units. The second step of decoding the coefficient information is a step of decoding the coefficient information exceeding 3 (S3110).

Alternatively, the first decoded information may mean the maximum number of coefficient information that can be transmitted in a predetermined unit. Here, the coefficient information may include at least one of 0 excess coefficient information, 1 excess coefficient information, Parity information, or 3 excess coefficient information. In this case, the step of decoding the coefficient information exceeding 3 may be included in the step of decoding the coefficient information.

Specifically, it is possible to decode the zero-over coefficient information indicating whether the absolute value of the current transform coefficient is greater than zero. If it is determined that the current transform coefficient is not 0, it is possible to decode the coefficient information exceeding 1 indicating whether the current transform coefficient exceeds the absolute value 1. Thereafter, when it is determined that the absolute value of the current transform coefficient is greater than 1 by the excess coefficient information, the parity information and the excess coefficient information 3 can be decoded.

At this time, if the zero excess coefficient information, the one excess coefficient information, the parity information, and the three excess coefficient information are decoded, the number of first decoded information is reduced. For example, if at least one of the 0 excess coefficient information, 1 excess coefficient information, Parity information, or 3 excess coefficient information is decoded, the number of first decoded information may be reduced by 1. Alternatively, the number of the first decoded information may be decreased by 1 whenever at least one of the 0 excess coefficient information, 1 excess coefficient information, Parity information, or 3 excess coefficient information is respectively decoded.

In other words, the number of first decoded information may mean the maximum number of coefficient information allowed for one block. Here, the block may mean a transform block or a sub-block of the transform block. In addition, the coefficient information may include at least one of 0 excess coefficient information, 1 excess coefficient information, Parity information, or 3 excess coefficient information. The number of first decoded information may be defined in units of a video sequence, picture, slice, coding tree block (CTU), coding block (CU), transform block (TU), or sub block of the transform block. That is, the same number of first decoded information may be set for all transform blocks or sub-blocks belonging to the corresponding unit.

PosC means the position of the transform coefficient to be currently decoded. When PosL is smaller than PosC (S3112), it can be seen that information on the current transform coefficient is decoded in the first step coefficient information decoding. After decoding the N excess coefficient information, the minimum absolute value of the current coefficient, which can be known as the parity information of the current transform coefficient, is subtracted from the current coefficient value, and then the absolute value of the difference coefficient can be decoded (S3113). If the value of the current coefficient is completely decoded by decoding the N excess coefficient information, the step of decoding the absolute value of the difference coefficient may be omitted (S3113). When PosL is larger than PosC, absolute value decoding capable of decoding the current transform coefficient information at once may be performed (S3114). Thereafter, sine information decoding indicating the sine information of the current transform coefficient may be decoded (S3115). If all information about the current transform coefficient is decoded, the next coefficient in the sub-block can be selected as the current coefficient by reducing the PosC value by 1 (S3117), and if the current transform coefficient is the last coefficient in the sub-block, the first threshold value, the first 2 The threshold may be updated (S3118).

The first and second threshold values may be adjusted when the number of transform coefficients in which the absolute value of the current coefficient itself is decoded in the current sub-block is C (C is an integer of 0 or more) or more. For example, when the first threshold value is 13, the first decrypted information number is 15, the second threshold value is 2, and the second decrypted information number is 2, the first and second decrypted information are first. In this case, since the second threshold value is reached, the first and second threshold values can be updated. Also, for example, if the first threshold is 13, the first decrypted information number is 15, the second threshold value is 2, and the second decrypted information number is 1, the first decrypted information is the first threshold value. However, since the second threshold value has not reached the second decrypted information, the first threshold value may be increased and the second threshold value may be updated in a direction of decreasing. Alternatively, when the first and second decoded information do not reach both the first and second threshold values, the first and second threshold values may be updated to decrease the first and second threshold values. Alternatively, updates may also be performed in a direction to maintain the first and second threshold values.

If the current sub-block is not the last sub-block (S3119), it moves to the next sub-block (S3120), and if it is the last sub-block (S3119), decoding of the transform block may be ended.

Various embodiments of the present disclosure are not intended to list all possible combinations, but are intended to describe representative aspects of the present disclosure, and the items described in various embodiments may be applied independently or in combination of two or more.

In addition, various embodiments of the present disclosure may be implemented by hardware, firmware, software, or a combination thereof. For implementation by hardware, one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), Universal It can be implemented by a processor (general processor), a controller, a microcontroller, a microprocessor.

The scope of the present disclosure includes software or machine-executable instructions (eg, operating systems, applications, firmware, programs, etc.) that cause an operation according to the method of various embodiments to be executed on a device or computer, and such software or Instructions include a non-transitory computer-readable medium that is stored and executable on a device or computer.

Claims (6)

Determining a prediction block of a current block belonging to the current picture, using a pre-restored area in the current picture;
Restoring a transform block of the current block; And
And restoring the current block based on the prediction block and the transform block.
Determining the prediction block,
Determining a candidate for deriving motion information of the current block; The candidate refers to motion information of neighboring blocks spatially adjacent to the current block,
Constructing a candidate list of the current block based on the candidate; And
And determining motion information of the current block from the candidate list. According to claim 1,
The prediction block is limited to belong to the same coding tree unit (CTU) or CTU row as the current block. According to claim 1,
The motion information of the neighboring block is selectively added to the candidate list based on whether the size of the current block is greater than a predetermined threshold size. According to claim 1,
The candidate list further includes motion information stored in a buffer of the decoding apparatus. According to claim 1,
The current block is divided into a plurality of sub-blocks,
Restoring the transform block,
Decoding sub-block information for a sub-block of the current block; The sub-block information indicates whether there is at least one non-zero coefficient in the sub-block, and
According to the sub-block information, if there is at least one non-zero coefficient in the sub-block, at least one of the over-count coefficient information, the over-count coefficient information, the parity information, or the over-count coefficient information for the current coefficient in the sub-block. And decoding one. The method of claim 5,
The number information for the sub-block is decoded,
The number information means the maximum number of coefficient information transmitted for the sub-block,
The coefficient information includes at least one of the zero excess coefficient information, the one excess coefficient information, the parity information, or the three excess coefficient information,
The number information is incremented by 1 each time at least one of the 0 excess coefficient information, the 1 excess coefficient information, the parity information, or the 3 excess coefficient information is respectively decoded.

Images