KR102389267B1 - A method and an apparatus for processing a video signal based on reference between components - Google Patents

Abstract

A video signal processing method and apparatus according to the present invention derives a first predicted value of a chrominance block using a sample of a luminance block, calculates a compensation parameter based on a predetermined reference region, and adds the compensation parameter to the first predicted value By application, a second predicted value of the chrominance block may be derived, and the chrominance block may be reconstructed based on the second predicted value of the chrominance block.

Description

A METHOD AND AN APPARATUS FOR PROCESSING A VIDEO SIGNAL BASED ON REFERENCE BETWEEN COMPONENTS

The present invention relates to a method and apparatus for encoding/decoding a video signal.

The demand for high-resolution, high-quality images is increasing in various application fields. As the image data becomes higher resolution and higher quality, the amount of data relatively increases compared to the existing image data. The storage cost will increase. High-efficiency image compression techniques can be used to solve these problems that occur as image data becomes high-resolution and high-quality.

An object of the present invention is to improve encoding/decoding efficiency of a prediction block.

The present invention aims to improve the accuracy of intra prediction for each component.

An object of the present invention is to improve encoding/decoding efficiency through adaptive block division.

A video signal processing method and apparatus according to the present invention derives a first predicted value of a chrominance block using a sample of a luminance block, calculates a compensation parameter based on a predetermined reference region, and compensates the first predicted value A parameter may be applied to derive a second predicted value of the chrominance block, and the chrominance block may be reconstructed based on the second predicted value of the chrominance block.

In the video signal processing method and apparatus according to the present invention, the calculating may further include determining a reference region referred to for calculating the compensation parameter.

In the video signal processing method and apparatus according to the present invention, the reference region may be determined for at least one of the luminance block and the chrominance block.

In the video signal processing method and apparatus according to the present invention, the compensation parameter may be calculated based on at least one of a representative value of a reference region of the luminance block and a representative value of a reference region of the chrominance block.

In the method and apparatus for processing a video signal according to the present invention, the representative value may be derived from any one of an average value, a minimum value, a maximum value, a mode, and a median value of all or some samples belonging to the reference region.

In the video signal processing method and apparatus according to the present invention, the step of deriving the first prediction value may be selectively performed based on information indicating whether the chrominance block is decoded through inter-component reference-based prediction. .

In the video signal processing method and apparatus according to the present invention, the chrominance block may be a first chrominance block (Cr block), and the second chrominance block (Cb block) may be reconstructed using samples of the first chrominance block. there is

In the video signal processing method and apparatus according to the present invention, the luminance block or the chrominance block may be divided into variable sizes/shapes based on at least one of a quad tree, a binary tree, and a triple tree.

According to the present invention, prediction encoding/decoding efficiency can be improved through inter-component reference-based prediction.

In addition, according to the present invention, encoding/decoding efficiency can be improved through block division of a tree structure.

1 is a schematic block diagram of an encoding apparatus according to an embodiment of the present invention.
2 is a schematic block diagram of a decoding apparatus according to an embodiment of the present invention.
3 illustrates a block division type as an embodiment to which the present invention is applied.
4 illustrates a block partitioning method based on a tree structure as an embodiment to which the present invention is applied.
5 illustrates a process of reconstructing a color difference block through reference between components as an embodiment to which the present invention is applied.
6 and 7 show an example of a reference region for inter-component reference as an embodiment to which the present invention is applied.
8 illustrates a method of determining a region of a luminance block used for reference between components of a chrominance block according to an embodiment to which the present invention is applied.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. In describing each figure, like reference numerals have been used for like elements.

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

When a component is referred to as being “connected” or “connected” to another component, it is understood that the other component may be directly connected or connected to the other component, but other components may exist in between. it should be On the other hand, when it is mentioned that a certain element is "directly connected" or "directly connected" to another element, it should be understood that no other element is present in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

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

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

Referring to FIG. 1 , the encoding apparatus 100 includes a picture division unit 110 , prediction units 120 and 125 , a transform unit 130 , a quantization unit 135 , a rearrangement unit 160 , and an entropy encoding unit 165 . ), an inverse quantization unit 140 , an inverse transform unit 145 , a filter unit 150 , and a memory 155 .

Each of the components shown in FIG. 1 is independently illustrated to represent different characteristic functions in the image encoding apparatus, which may mean that each component is made of separate hardware. However, each component is included in a list for convenience of description, 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 a function, Integrated embodiments and separate 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 addition, some of the components are not essential components for performing essential functions in the present invention, but may be optional components for merely improving performance. The present invention can be implemented by including only essential components to implement the essence of the present invention, except for components used for performance improvement, and a structure including only essential components excluding optional components used for performance improvement Also included in the scope of the present invention.

The picture divider 110 may divide the input picture into at least one block. In this case, a block may mean a coding unit (CU), a prediction unit (PU), or a transformation unit (TU). The division may be performed based on at least one of a quadtree, a binary tree, and a triple tree. The quad tree divides the upper block into lower blocks whose width and height are half that of the upper block. Binary tree is a method of dividing the upper block into lower blocks whose either width or height is half that of the upper block. In a binary tree, a block may have a non-square shape as well as a square shape through the binary tree-based division in which the upper block is half the height.

Hereinafter, in an embodiment of the present invention, a coding unit may be used as a unit for performing encoding or may be used as a meaning for a unit for performing decoding.

The prediction units 120 and 125 may include an inter prediction unit 120 performing inter prediction and an intra prediction unit 125 performing intra prediction. Whether to use inter prediction or to perform intra prediction for a prediction unit may be determined, and specific information (eg, intra prediction mode, motion vector, reference picture, etc.) according to each prediction method may be determined. In this case, a processing unit in which prediction is performed and a processing unit in which a prediction method and specific content are determined may be different. For example, a prediction method and a prediction mode may be determined in a prediction unit, and prediction may be performed in a transformation unit. A residual value (residual block) between the generated prediction block and the original block may be input to the transform unit 130 . Also, prediction mode information, motion vector information, etc. used for prediction may be encoded by the entropy encoder 165 together with the residual value and transmitted to the decoding apparatus. When a specific encoding mode is used, the original block may be encoded and transmitted to the decoder without generating the prediction block through the predictors 120 and 125 .

The inter prediction unit 120 may predict a prediction unit based on information on at least one of a picture before or after the current picture, and in some cases, prediction based on information of a partial region in the current picture that has been encoded Units can also be predicted. The inter prediction unit 120 may include a reference picture interpolator, a motion prediction unit, and a motion compensator.

The reference picture interpolator may receive reference picture information from the memory 155 and generate pixel information of integer pixels or less in the reference picture. In the case of luminance pixels, a DCT-based 8-tap interpolation filter in which filter coefficients are different to generate pixel information of integer pixels or less in units of 1/4 pixels may be used. In the case of the color difference signal, a DCT-based 4-tap interpolation filter in which filter coefficients are different to generate pixel information of integer pixels or less in units of 1/8 pixels may be used.

The motion prediction unit may perform motion prediction based on the reference picture interpolated by the reference picture interpolator. 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) may be used. The motion vector may have a motion vector value of 1/2 or 1/4 pixel unit based on the interpolated pixel. The motion prediction unit may predict the current prediction unit by using a different motion prediction method. As the motion prediction method, various methods such as a skip method, a merge method, and an AMVP (Advanced Motion Vector Prediction) method may be used.

The intra prediction unit 125 may generate a prediction unit based on reference pixel information around the current block, which is pixel information in the current picture. When the neighboring block of the current prediction unit is a block on which inter prediction is performed, and thus the reference pixel is a pixel on which inter prediction is performed, the reference pixel included in the block on which the inter prediction is performed is a reference pixel of the block on which the intra prediction is performed. information can be used instead. That is, when the reference pixel is not available, the unavailable reference pixel information may be replaced with at least one reference pixel among the available reference pixels.

In intra prediction, the prediction mode may have a directional prediction mode in which reference pixel information is used according to a prediction direction and a non-directional mode in which directional information is not used when prediction is performed. A mode for predicting a luminance component may be different from a mode for predicting a chrominance component, and the chrominance component may be predicted using an intra prediction mode used for predicting the luminance component or a predicted/restored luminance component.

The intra prediction method may generate a prediction block after applying an adaptive intra smoothing (AIS) filter to a reference pixel according to an intra prediction mode. The type of AIS filter applied to the reference pixel may be different. In order to perform the intra prediction method, the intra prediction mode of the current prediction unit may be predicted from the intra prediction mode of the prediction unit existing around the current prediction unit. When the prediction mode of the current prediction unit is predicted using mode information predicted from the neighboring prediction unit, if the intra prediction mode of the current prediction unit and the neighboring prediction unit are the same, the current prediction unit and the neighboring prediction unit are used using predetermined flag information It is possible to transmit information that the intra-prediction modes are the same, and if the intra-prediction modes of the current prediction unit and the neighboring prediction units are different from each other, entropy encoding may be performed to encode intra-prediction mode information of the current block.

Also, a residual block including residual information that is a difference value between the prediction unit generated by the prediction units 120 and 125 and the original block may be generated. The generated residual block may be input to the transform unit 130 .

The transform unit 130 may transform the residual block including the residual data by using a transform type such as DCT or DST. In this case, the transform type may be determined based on the intra prediction mode of the prediction unit used to generate the residual block.

The quantization unit 135 may quantize values transformed in the frequency domain by the transform unit 130 . The quantization coefficient may vary according to blocks or the importance of an image. The value calculated by the quantization unit 135 may be provided to the inverse quantization unit 140 and the rearrangement unit 160 .

The reordering unit 160 may reorder coefficient values on the quantized residual block. The reordering unit 160 may change the coefficient in the form of a two-dimensional block into a form of a one-dimensional vector through a coefficient scanning method. For example, the reordering unit 160 may scan from DC coefficients to coefficients in a high frequency region using a predetermined scan type, and may change it into a one-dimensional vector form.

The entropy encoding unit 165 may perform entropy encoding based on the values calculated by the reordering unit 160 . For entropy encoding, various encoding methods such as Exponential Golomb, Context-Adaptive Variable Length Coding (CAVLC), and Context-Adaptive Binary Arithmetic Coding (CABAC) may be used.

The entropy encoding unit 165 receives the residual coefficient information and block type information, prediction mode information, division unit information, prediction unit information and transmission unit information, and motion vector of the coding unit from the reordering unit 160 and the prediction units 120 and 125 . Various information such as information, reference frame information, interpolation information of a block, and filtering information may be encoded.

The entropy encoder 165 may entropy-encode the coefficient values of the coding units input from the reordering unit 160 .

The inverse quantizer 140 and the inverse transform unit 145 inversely quantize the values quantized by the quantizer 135 and inversely transform the values transformed by the transform unit 130 . The residual values generated by the inverse quantizer 140 and the inverse transform unit 145 are combined with the prediction units predicted through the motion estimation unit, the motion compensator, and the intra prediction unit included in the prediction units 120 and 125 and restored. You can create a Reconstructed Block.

The filter unit 150 may include at least one of a deblocking filter, an offset correcting unit, and an adaptive loop filter (ALF).

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

The offset correcting unit may correct an offset from the original image in units of pixels with respect to the image on which the deblocking has been performed. In order to perform offset correction on a specific picture, a method of dividing pixels included in an image into a certain number of regions, determining the region to be offset and applying the offset to the region, or taking edge information of each pixel into account can be used to apply

Adaptive loop filtering (ALF) may be performed based on a value obtained by comparing the filtered reconstructed image and the original image. After dividing the pixels included in the image into a predetermined group, one filter to be applied to the corresponding group is determined, and filtering can be performed differentially for each group. As for information related to whether to apply ALF, the luminance signal may be transmitted for each coding unit (CU), and the shape and filter coefficients of the ALF filter to be applied may vary according to each block. In addition, the ALF filter of the same type (fixed type) may be applied regardless of the characteristics of the block to be applied.

The memory 155 may store the reconstructed block or picture calculated through the filter unit 150 , and the stored reconstructed block or picture may be provided to the predictors 120 and 125 when inter prediction is performed.

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

Referring to FIG. 2 , the decoding apparatus 200 includes an entropy decoding unit 210 , a reordering unit 215 , an inverse quantization unit 220 , an inverse transform unit 225 , prediction units 230 and 235 , and a filter unit 240 . ), a memory 245 may be included.

Each of the constituent units shown in FIG. 2 is independently illustrated to represent different characteristic functions in the decoding apparatus, which may mean that each constituent unit is made of separate hardware. However, each component is listed as each component for convenience of description, and at least two components of each component are combined to form one component, or one component can be divided into a plurality of components to perform a function, such as Integrated embodiments and separate embodiments of each component are also included in the scope of the present invention without departing from the essence of the present invention.

The entropy decoding unit 210 may perform entropy decoding on the input bitstream. For example, for entropy decoding, various methods such as Exponential Golomb, Context-Adaptive Variable Length Coding (CAVLC), and Context-Adaptive Binary Arithmetic Coding (CABAC) may be applied.

The entropy decoding unit 210 may decode information related to intra prediction and inter prediction performed by the encoding apparatus.

The reordering unit 215 may reorder the bitstream entropy decoded by the entropy decoding unit 210 . Coefficients expressed in the form of a one-dimensional vector may be restored and rearranged as coefficients in the form of a two-dimensional block. The reordering unit 215 may receive information related to coefficient scanning performed by the encoding apparatus, and may perform rearrangement by performing a reverse scanning method based on the scanning order performed by the encoding apparatus.

The inverse quantization unit 220 may perform inverse quantization based on the quantization parameter and the reordered coefficient values of the blocks.

The inverse transform unit 225 may perform inverse transform on the inverse quantized transform coefficient into a predetermined transform type. In this case, the transform type is at least one of information about a prediction mode (inter/intra prediction), block size/shape, intra prediction mode, component type (luminance/chrominance component), partition type (QT, BT, TT, etc.) can be determined based on

The prediction units 230 and 235 may generate a prediction block based on the prediction block generation related information provided from the entropy decoding unit 210 and previously decoded block or picture information provided from the memory 245 .

The prediction units 230 and 235 may include a prediction unit determiner, an inter prediction unit, and an intra prediction unit. The prediction unit determiner receives various information such as prediction unit information input from the entropy decoder 210 , intra prediction mode related information of the intra prediction method, and motion prediction related information of the inter prediction method, and predicts in the current coding unit (CU). The units may be distinguished, and it may be determined whether the prediction unit performs inter prediction or intra prediction. The inter prediction unit 230 uses information necessary for inter prediction of the current prediction unit provided from the encoding apparatus, and based on information included in at least one of a picture before or after the current picture including the current prediction unit. Inter prediction may be performed on the current prediction unit. Alternatively, inter prediction may be performed based on information on a pre-restored partial region in the current picture including the current prediction unit. To this end, the pre-restored partial region may be added to the reference picture list.

In order to perform inter prediction, based on a coding unit, a motion prediction method of a prediction unit included in a corresponding coding unit is a skip mode, a merge mode, an AMVP mode, and a current picture reference mode. It can be determined which method is used.

The intra prediction unit 235 may generate a prediction block based on pixel information in the current picture. When the prediction unit is a prediction unit on which intra prediction is performed, intra prediction may be performed based on intra prediction mode information of the prediction unit provided by the encoding apparatus. The intra prediction unit 235 may include an adaptive intra smoothing (AIS) filter, a reference pixel interpolator, and a DC filter. The AIS filter is a part that performs filtering on the reference pixel of the current block, and can be applied by determining whether to apply the filter according to the prediction mode of the current prediction unit. AIS filtering may be performed on the reference pixel of the current block by using the prediction mode and AIS filter information of the prediction unit provided by the encoding apparatus. When the prediction mode of the current block is a mode in which AIS filtering is not performed, the AIS filter may not be applied.

When the prediction mode of the prediction unit is a prediction unit in which intra prediction is performed based on a pixel value obtained by interpolating the reference pixel, the reference pixel interpolator may interpolate the reference pixel to generate a reference pixel of a pixel unit having an integer value or less. When the prediction mode of the current prediction unit is a prediction mode that generates a prediction block without interpolating the 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 reconstructed block or picture may be provided to the filter unit 240 . The filter unit 240 may include a deblocking filter, an offset correcting unit, and an ALF.

Information on whether a deblocking filter is applied to a corresponding block or picture and information on whether a strong filter or a weak filter is applied when the deblocking filter is applied may be provided from the encoding apparatus. The deblocking filter of the decoding apparatus may receive deblocking filter related information provided from the encoding apparatus, and the decoding apparatus may perform deblocking filtering on the corresponding block.

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

ALF may be applied to a coding unit based on information on whether ALF is applied, ALF coefficient information, etc. provided from the encoder. Such ALF information may be provided by being included in a specific parameter set.

The memory 245 may store the reconstructed picture or block to be used as a reference picture or reference block, and may also provide the reconstructed picture to an output unit.

3 illustrates a block division type as an embodiment to which the present invention is applied.

One block (hereinafter, referred to as a first block) may be divided into a plurality of sub-blocks (hereinafter, referred to as a second block) by at least one of a vertical line and a horizontal line. The vertical line and the horizontal line may be one, two or more. Here, the first block may be a coding block (CU), which is a basic unit of image encoding/decoding, a prediction block (PU), which is a basic unit of prediction encoding/decoding, or a transform block (TU), which is a basic unit of transform encoding/decoding. there is. The first block may be a square block or a non-square block.

The division of the first block may be performed based on a quad tree, a binary tree, a triple tree, and the like, and will be described in detail below with reference to FIG. 3 .

Figure 3 (a) shows a quad tree partitioning (QT). QT is a division type in which a first block is divided into four second blocks. For example, when a first block of 2Nx2N is divided into QTs, the first block may be divided into four second blocks having a size of NxN. QT may be limited to be applied only to square blocks, but it is also possible to apply to non-square blocks.

FIG. 3(b) shows the division of a horizontal binary tree (hereinafter referred to as Horizontal BT). Horizontal BT is a division type in which a first block is divided into two second blocks by one horizontal line. The dichotomy may be performed symmetrically or asymmetrically. For example, when a first block of 2Nx2N is divided into Horizontal BT, the first block may be divided into two second blocks having a height ratio of (a:b). Here, a and b may have the same value, and a may be larger or smaller than b.

FIG. 3( c ) illustrates partitioning of a vertical binary tree (hereinafter, referred to as Vertical BT). Vertical BT is a division type in which a first block is divided into two second blocks by one vertical line. The dichotomy may be performed symmetrically or asymmetrically. For example, when a first block of 2Nx2N is divided into vertical BT, the first block may be divided into two second blocks having a width ratio of (a:b). Here, a and b may have the same value, and a may be larger or smaller than b.

3( d ) is a diagram illustrating a horizontal triple tree (hereinafter referred to as Horizontal TT) partitioning. Horizontal TT is a division type in which a first block is divided into three second blocks by two horizontal lines. For example, when the first block of 2Nx2N is divided by Horizontal TT, the first block may be divided into three second blocks having a height ratio of (a:b:c). Here, a, b, and c may have the same value. Alternatively, a and c may be the same, and b may be greater than or less than a.

FIG. 3(e) illustrates a vertical triple tree (hereinafter referred to as Vertical TT) partitioning. Vertical TT is a division type in which a first block is divided into three second blocks by two vertical lines. For example, when the first block of 2Nx2N is divided by vertical TT, the first block may be divided into three second blocks having a width ratio of (a:b:c). Here, a, b, and c may have the same value or different values. Alternatively, a and c may be the same, and b may be greater than or less than a. Alternatively, a and b may be the same, and c may be greater than or less than a. Alternatively, b and c may be the same, and a may be greater than or less than b.

The above-described division may be performed based on division information signaled from the encoding apparatus. The division information may include at least one of division type information, division direction information, and division ratio information.

The partition type information may specify any one of partition types pre-defined in the encoding/decoding apparatus. The pre-defined splitting type may include at least one of QT, Horizontal BT, Vertical BT, Horizontal TT, Vertical TT, and No split mode. Alternatively, the partition type information may mean information on whether QT, BT, or TT is applied, which may be encoded in the form of a flag or an index. The division direction information may indicate whether the division is divided in a horizontal direction or a vertical direction in the case of BT or TT. The division ratio information may indicate a ratio of a width and/or a height of the second block in the case of BT or TT.

4 illustrates a block partitioning method based on a tree structure as an embodiment to which the present invention is applied.

It is assumed that the block 400 illustrated in FIG. 4 is a square block (hereinafter, referred to as a first block) having a size of 8Nx8N and a division depth of k. When the partition information of the first block indicates QT partitioning, the first block may be divided into four sub-blocks (hereinafter, referred to as a second block). The second block may have a size of 4Nx4N and may have a division depth of (k+1).

The four second blocks may be divided again based on any one of QT, BT, TT, or non-split mode. For example, when the partition information of the second block indicates a binary tree (Horizontal BT) in the horizontal direction, the second block is divided into two sub-blocks (hereinafter, referred to as the third block 410 ) as in the second block 410 of FIG. 4 . It can be divided into blocks). In this case, the third block may have a size of 4Nx2N and may have a division depth of (k+2).

The third block may also be divided again based on any one of QT, BT, TT, or non-split mode. For example, when the partition information of the third block indicates a binary tree (Vertical BT) in the vertical direction, the third block is divided into two sub-blocks 411 and 412 as shown in FIG. 4 . can be In this case, the sub-blocks 411 and 412 may have a size of 2Nx2N and may have a division depth of (k+3). Alternatively, when the partition information of the third block indicates a horizontal binary tree (Horizontal BT), the third block may be divided into two sub-blocks 413 and 414 as shown in FIG. 4 . there is. In this case, the sub-blocks 413 and 414 may have a size of 4NxN and may have a division depth of (k+3).

The division may be performed independently or in parallel with neighboring blocks, or may be performed sequentially according to a predetermined priority.

The division information of the current block to be divided may be determined dependently based on at least one of the division information of the upper block of the current block and the division information of the neighboring blocks. For example, when the second block is divided into Horizontal BT and the upper third block is divided into Vertical BT, the third block at the bottom does not need to be divided into Vertical BT. This is because, when the lower third block is divided into vertical BT, the same result is obtained as the second block is divided into QT. Accordingly, the encoding of the partition information (particularly, the partition direction information) of the lower third block may be omitted, and the decoding apparatus may set the lower third block to be partitioned in the horizontal direction.

The upper block may mean a block having a division depth smaller than a division depth of the current block. For example, when the division depth of the current block is (k+2), the division depth of the upper block may be (k+1). The neighboring block may be a block adjacent to the top or left side of the current block. The neighboring block may be a block having the same division depth as the current block.

The aforementioned division may be repeatedly performed up to a minimum unit of encoding/decoding. In the case of splitting into the smallest unit, the splitting information on the corresponding block is no longer signaled from the encoding apparatus. The information on the minimum unit may include at least one of a size and a shape of the minimum unit. The size of the minimum unit may be expressed as a block width, a height, a minimum value or a maximum value among width and height, a sum of the width and height, the number of pixels, a division depth, and the like. The information on the minimum unit may be signaled in at least one of a video sequence, a picture, a slice, or a block unit. Alternatively, the information on the minimum unit may be a value pre-promised to the encoding/decoding apparatus. The information on the minimum unit may be signaled for each CU, PU, and TU. Information on one minimum unit may be equally applied to a CU, a PU, and a TU.

5 illustrates a process of reconstructing a color difference block through reference between components as an embodiment to which the present invention is applied.

Inter-component reference of the present invention may refer to a method of predicting/restoring a chrominance component (hereinafter, referred to as a chrominance block) of the current block based on a luminance component (hereinafter, referred to as a luminance block) of the current block.

Referring to FIG. 5 , a first predicted value of a chrominance block may be derived using a sample of the luminance block ( S500 ).

A sample of the luminance block corresponding to the position of the first predicted value of the chrominance block may be set as the first predicted value of the chrominance block. Alternatively, the first predicted value may be derived by resizing the luminance block to the resolution of the chrominance block. The resizing may be performed based on filtering such as down-sampling and sub-sampling.

Meanwhile, there may exist a case where the color difference block corresponds to a plurality of luminance blocks. In this case, a process of determining a region corresponding to the chrominance block within the plurality of luminance blocks may be involved, which will be described with reference to FIG. 8 .

A sample of the luminance block may be a predicted value or a restored value. The prediction value may be obtained through intra prediction or inter prediction. The restored value may be a first value obtained by adding a residual sample to the prediction value, or may be a second value obtained by applying an in-loop filter to the first value.

The intra prediction may be performed based on a predetermined intra prediction mode and a peripheral area of the luminance block.

The intra prediction mode may be determined as one of two non-directional modes and p directional modes. Here, p may be 33, 65, 129 or more. The p may be a fixed value pre-promised to the encoding/decoding apparatus, or may be variably determined based on encoding information. Here, the encoding information may include not only information encoded and signaled by the encoding apparatus, but also information derived based on the information signaled by the decoding apparatus. For example, the encoding information may include block size/form, block availability, partition type, number of partitions, component type, prediction mode, information on intra prediction mode, inter mode, motion information, transform type, transform skip mode, It may include information about non-zero residual coefficients, scan order, color format, in-loop filter information, and the like.

The block size may be expressed as any one of width and height, a minimum/maximum value of width and height, a sum of width and height, the number of samples belonging to a block, and the like. The availability of the block may be determined in consideration of a block position, a range of a parallel processing region, a decoding order, and the like. The prediction mode may mean information indicating an intra mode or an inter mode. The information about the intra prediction mode includes whether the intra prediction mode is a non-directional mode, whether the intra prediction mode is a vertical/horizontal mode, the directionality of the intra prediction mode, and the number of intra prediction modes pre-defined in the encoding/decoding device. It may include information about The inter mode may mean information indicating a merge/skip mode, an AMVP mode, or a current picture reference mode. The current picture reference mode refers to a method of predicting a current block using a pre-reconstructed region of the current picture. The current picture may be a picture to which the current block belongs. The current picture may be added to a reference picture list for inter prediction, and the current picture may be arranged after a short-term reference picture or a long-term reference picture in the reference picture list. The motion information may include a prediction direction flag, a motion vector, a reference picture index, and the like. The encoding information may relate to a current block and/or a neighboring block.

The peripheral region is a region restored before the luminance block according to a decoding order, and may include at least one of left, upper, right, lower, or adjacent regions of each corner of the luminance region.

The peripheral region may include one, two, three, four or more lines. For example, one or more horizontal lines positioned at the top of the luminance block may be determined as the peripheral region, and one or more vertical lines positioned at the left of the luminance block may be determined as the peripheral region. The number of lines belonging to the peripheral region may be a fixed number (eg, one) pre-promised to the encoding/decoding apparatus, or may be variably determined based on encoding information. Here, the encoding information may include not only information encoded and signaled by the encoding apparatus, but also information derived based on the information signaled by the decoding apparatus. For example, the encoding information may include block size/form, block availability, partition type, number of partitions, component type, prediction mode, information on intra prediction mode, inter mode, motion information, transform type, transform skip mode, It may include information about non-zero residual coefficients, scan order, color format, in-loop filter information, and the like.

The block size may be expressed by any one of width and height, a minimum/maximum value of width and height, a sum of width and height, the number of samples belonging to a block, and the like. The availability of the block may be determined in consideration of a block location, a range of a parallel processing region, a decoding order, and the like. The prediction mode may mean information indicating an intra mode or an inter mode. The information on the intra prediction mode includes whether the intra prediction mode is a non-directional mode, whether the intra prediction mode is a vertical/horizontal mode, the directionality of the intra prediction mode, and the number of intra prediction modes pre-defined in the encoding/decoding device. It may include information about The inter mode may mean information indicating a merge/skip mode, an AMVP mode, or a current picture reference mode. The current picture reference mode refers to a method of predicting a current block using a pre-reconstructed region of the current picture. The current picture may be a picture to which the current block belongs. The current picture may be added to a reference picture list for inter prediction, and the current picture may be arranged after a short-term reference picture or a long-term reference picture in the reference picture list. The motion information may include a prediction direction flag, a motion vector, a reference picture index, and the like. The encoding information may relate to a current block and/or a neighboring block.

Referring to FIG. 5 , a compensation parameter may be calculated based on a predetermined reference region ( S510 ).

The encoding/decoding apparatus may determine a reference region to calculate the compensation parameter of the chrominance block, which is hereinafter referred to as a reference region. A method of determining the reference region will be described with reference to FIGS. 6 and 7 .

The reference region may be defined for each component type. That is, the reference region may include at least one of a reference region of a luminance block (hereinafter, referred to as a luminance reference region) or a reference region of a chrominance block (hereinafter, a chrominance reference region). The color difference block may include at least one of a Cb block and a Cr block. The aforementioned reference region may be a pre-restored region adjacent to the periphery of the block, wherein the pre-reconstructed region may be a restoration region before the in-loop filter is applied, or restoration after the in-loop filter is applied. It may be an area.

The compensation parameter may be calculated based on whether the linearity between the representative value of the luminance reference region and the luminance block is the same as/similar to the linearity between the representative value of the chrominance reference region and the chrominance block. The compensation parameter may be calculated in the form of at least one of a weighting factor, an offset, and a filter coefficient.

The representative value of the luminance reference region may be derived using all or some samples belonging to the luminance reference region.

The positions of the partial samples may be pre-promised to the encoding/decoding device (first embodiment). For example, the position of the partial sample may be a position adjacent to at least one of a left, an upper, or an upper left of the upper-left sample of the luminance block. The positions of the partial samples may be determined dependently on the positions of the samples in the luminance block (second embodiment). For example, the partial sample may have the same x-coordinate or y-coordinate as a sample of the luminance block. The some samples may be determined depending on the intra prediction mode of the luminance block (third embodiment). For example, the intra prediction mode may be expressed as an angular line having a predetermined angle, and in this case, some samples may be located on the same angular line as the samples of the luminance block. When there is no integer sample (integer pel) on the angular line, integer samples located on both sides of the angular line may be used as the partial sample. The partial sample may be determined through a combination of at least two of the first to third embodiments described above. The number of the partial samples may be 1, 2, 3, 4, 5 or more. The number may be a fixed value pre-promised to the encoding/decoding device, and the position of the sample of the luminance block, whether the intra prediction mode is the non-directional mode, the angle of the directional mode, the size/shape of the luminance block, etc. are taken into consideration may be variably determined.

The representative value may be derived as an average value, a minimum value, a maximum value, a mode value, or a median value of all or some samples belonging to the luminance reference region. Alternatively, the representative value may be derived by applying a predetermined filter to all or some samples belonging to the luminance reference region. The filter may be pre-defined in the encoding/decoding device. The pre-defined filters may be one, two, or more, and any one of the plurality of filters may be selectively selected in consideration of the size/shape of the luminance block, the prediction mode, information about the intra prediction mode, filter strength, etc. may be used. Any one of the plurality of filters may be different from the other filter in at least one of a filter length, a filter strength, and a filter coefficient. The information on the intra prediction mode includes whether the intra prediction mode is a non-directional mode, whether the intra prediction mode is a vertical/horizontal mode, the directionality of the intra prediction mode, and the number of intra prediction modes pre-defined in the encoding/decoding device. It may include information about

The representative value of the chrominance reference region may also be derived in the same/similar manner to the representative value of the luminance reference region described above, and a detailed description thereof will be omitted.

Referring to FIG. 5 , the second prediction value of the color difference block may be derived by applying the compensation parameter of S510 to the first prediction value of S500 ( S520 ).

As described above, the compensation parameter may be calculated in the form of a weight and/or an offset. In this case, the second predicted value of the color difference block may be derived by multiplying the first predicted value by a weight, or may be derived by adding or subtracting an offset to the first predicted value. As in Equation 1, it may be derived by applying both a weight and an offset to the first prediction value.

In Equation 1, Pred _C2 denotes a second predicted value, Pred _C1 denotes a first predicted value or a sample of a luminance block, and a and b denote a weight and an offset, respectively.

Alternatively, the compensation parameter may be calculated in the form of filter coefficients of an n-tap filter. The input value of the n-tap filter may include at least one of a first prediction value (or a sample of a luminance block), a representative value of a luminance reference region, and a representative value of a chrominance reference region. The output value of the n-tap filter may be a second prediction value of the color difference block.

Referring to FIG. 5 , the chrominance block may be reconstructed based on the second predicted value of the chrominance block derived in S520 ( S530 ).

In the case of prediction based on inter-component reference, the second prediction value may be set as a reconstructed value. That is, in the case of prediction based on inter-component reference, the decoding apparatus may omit the process of decoding the residual sample. Alternatively, even in the case of prediction based on inter-component reference, a reconstructed value of the chrominance block may be generated by adding a residual sample to the second predicted value of the chrominance block.

Meanwhile, the aforementioned inter-component reference-based prediction method may be selectively performed based on information signaled from the encoding apparatus (first embodiment). The information may indicate whether the color difference block is decoded through inter-component reference-based prediction, which may be signaled in the form of a flag or an index.

Alternatively, the decoding apparatus may determine whether to decode the chrominance block through inter-component reference-based prediction, based on predetermined encoding information (second embodiment). Here, the encoding information may include not only information encoded and signaled by the encoding apparatus, but also information derived based on the information signaled by the decoding apparatus. For example, the encoding information may include block size/form, block availability, partition type, number of partitions, component type, prediction mode, information on intra prediction mode, inter mode, motion information, transform type, transform skip mode, It may include information about non-zero residual coefficients, scan order, color format, in-loop filter information, and the like.

The block size may be expressed by any one of width and height, a minimum/maximum value of width and height, a sum of width and height, the number of samples belonging to a block, and the like. The availability of the block may be determined in consideration of a block location, a range of a parallel processing region, a decoding order, and the like. The prediction mode may mean information indicating an intra mode or an inter mode. The information on the intra prediction mode includes whether the intra prediction mode is a non-directional mode, whether the intra prediction mode is a vertical/horizontal mode, the directionality of the intra prediction mode, and the number of intra prediction modes pre-defined in the encoding/decoding device. It may include information about The inter mode may mean information indicating a merge/skip mode, an AMVP mode, or a current picture reference mode. The current picture reference mode refers to a method of predicting a current block using a pre-reconstructed region of the current picture. The current picture may be a picture to which the current block belongs. The current picture may be added to a reference picture list for inter prediction, and the current picture may be arranged after a short-term reference picture or a long-term reference picture in the reference picture list. The motion information may include a prediction direction flag, a motion vector, a reference picture index, and the like. The encoding information may relate to a current block and/or a neighboring block.

Alternatively, inter-component reference-based prediction may be performed only when the luminance block satisfies a specific condition (third embodiment). As an example of the specific condition, when the luminance block is encoded in the intra mode, the intra prediction mode of the luminance block is the non-directional mode, when the intra prediction mode of the luminance block is the vertical/horizontal mode, the size of the luminance block is a predetermined The number of non-zero residual coefficients belonging to the luminance block is predetermined when equal to or less than the threshold value, when the luminance block is encoded in merge/skip mode, when the residual coefficient of the luminance block is 0 (e.g., coded_block_flag=0) In a case below the threshold value of , there is a case in which in-loop filter information (e.g., deblocking filter, SAO, ALF) of a luminance block is derived from in-loop filter information of a neighboring block. The inter-component reference-based prediction may be selectively performed based on a combination of at least two of the first to third embodiments described above.

The chrominance block may include a first chrominance block (Cr block) and a second chrominance block (Cb block). Through the above-described inter-component reference-based prediction, the first chrominance block and the second chrominance block may be respectively decoded using samples of the luminance block.

Alternatively, the inter-component reference-based prediction may be applied between the luminance block and the chrominance block, or equally/similarly applied between the first chrominance block and the second chrominance block. In this case, the first chrominance block may be predicted/reconstructed using the sample of the luminance block through inter-component reference-based prediction. Then, the second chrominance block may be predicted/reconstructed using the sample of the first chrominance block through inter-component reference-based prediction.

Alternatively, the first chrominance block may be predicted/reconstructed using a sample of the luminance block through inter-component reference-based prediction. Then, the second chrominance block may be predicted/reconstructed through the weighted sum of the luminance block and the first chrominance block. The weight for the weighted sum may be calculated based on all or some samples of the aforementioned reference region. Alternatively, the weight may be encoded and signaled by the encoding apparatus, or may be determined as a value pre-promised to the encoding/decoding apparatus.

In the above-described embodiment, the restoration is performed in the order of the first chrominance block -> the second chrominance block, but it is also possible to restore in the order of the second chrominance block -> the first chrominance block. The order may follow a pre-promised order to the encoding/decoding device. Alternatively, the information specifying the order may be encoded and signaled, and the decoding apparatus may sequentially reconstruct the color difference block according to the signaled information.

6 and 7 show an example of a reference region for inter-component reference as an embodiment to which the present invention is applied.

As a region adjacent to the periphery of the luminance/chrominance block, a region pre-restored before the luminance/chrominance block according to a predetermined decoding order may be used as a reference region. For example, as shown in FIG. 6 , an area adjacent to the left or upper end of the luminance/chrominance block may be used as a reference area. Alternatively, as shown in FIG. 7 , the reference region may extend to regions adjacent to the upper right and lower left ends of the luminance/chrominance block. In addition, although not shown in FIGS. 6 and 7 , a region adjacent to the upper left end of the luminance/chrominance block and a region adjacent to the right, lower, or lower right end pre-restored according to the decoding order may also be used as reference regions.

The reference region may be determined based on at least one of encoding information of a luminance block and encoding information of a neighboring block. The determination may include determining at least one of a position, number, size (width/height), shape, length, or priority between candidate reference areas of the reference area. The candidate reference region means one or more candidate regions usable as a reference region, and the reference region may be determined as any one of the candidate reference regions. The neighboring block may mean a block reconstructed before the luminance block according to a decoding order. For example, the neighboring block may be a block adjacent to at least one of left, upper, right, lower, or each corner of the luminance block.

Here, the encoding information may include not only information encoded and signaled by the encoding apparatus, but also information derived based on the information signaled by the decoding apparatus. For example, the encoding information may include block size/form, block availability, partition type, number of partitions, component type, prediction mode, information on intra prediction mode, inter mode, motion information, transform type, transform skip mode, It may include information about non-zero residual coefficients, scan order, color format, in-loop filter information, and the like.

The block size may be expressed by any one of width and height, a minimum/maximum value of width and height, a sum of width and height, the number of samples belonging to a block, and the like. The availability of the block may be determined in consideration of a block location, a range of a parallel processing region, a decoding order, and the like. The prediction mode may mean information indicating an intra mode or an inter mode. The information on the intra prediction mode includes whether the intra prediction mode is a non-directional mode, whether the intra prediction mode is a vertical/horizontal mode, the directionality of the intra prediction mode, and the number of intra prediction modes pre-defined in the encoding/decoding device. It may include information about The inter mode may mean information indicating a merge/skip mode, an AMVP mode, or a current picture reference mode. The current picture reference mode refers to a method of predicting a current block using a pre-reconstructed region of the current picture. The current picture may be a picture to which the current block belongs. The current picture may be added to a reference picture list for inter prediction, and the current picture may be arranged after a short-term reference picture or a long-term reference picture in the reference picture list. The motion information may include a prediction direction flag, a motion vector, a reference picture index, and the like.

For example, when the luminance block is encoded in the intra mode, a region of a neighboring sample used for intra prediction may be determined as a reference region of the luminance/chrominance block. In this case, when filtering is applied to the neighboring samples in the intra prediction, the reference region of the luminance/chrominance block may be the region of the neighboring samples to which the filtering is applied or the region of the neighboring samples before the filtering is applied. The number of sample lines belonging to the reference area may be set to be the same as the number of sample lines belonging to the area of the neighboring sample, and the reference area may include N or M sample lines different from the area of the neighboring sample. there is.

Alternatively, according to an example, the encoding information of the luminance block may be derived based on encoding information of a neighboring block. For example, when the intra prediction mode of the luma block is derived from a neighboring block-based Most Probable Mode (MPM), when the luma block is encoded in a merge/skip mode or an AMVP mode, SAO filter information of the luma block There is a case in which is derived from SAO filter information of a neighboring block. In this case, all or a partial area of the neighboring block may be determined as the reference area.

Alternatively, when the size of the luminance block is less than or equal to the threshold, the left and upper reference regions are used. Otherwise, either the left or the upper reference region may be used. When the luminance block is NxM non-square (N>M), the upper reference region is used, and when the luminance block is NxM non-square (N<M), the left reference region may be used. When the intra prediction mode of the luminance block is the non-directional mode, the left and upper reference regions are used. Otherwise, either the left or the upper reference region may be used in consideration of the directionality of the intra prediction mode. In this case, when the direction is vertical, the upper reference area may be used, and when the direction is horizontal, the left reference area may be used.

Alternatively, information on the reference region may be signaled from the encoding apparatus. The decoding apparatus may determine the reference region based on the signaled information. The information on the reference region is information for specifying the reference region, and may include at least one of the position, number, size (width/height), shape, length, or priority of the reference region, or information about priority between candidate reference regions. there is. The information may be signaled in at least one of a video sequence, a picture, or a predetermined fragment area (eg, a slice, a tile, a block group, a block, etc.).

To this end, when there are m available reference regions, the encoding apparatus may allocate an index of 0 to (m-1) to each reference region, and may encode any one of the m reference regions. The information may be signaled for each of the luminance block and the chrominance block, and the luminance block and the chrominance block may use reference regions at different positions. Alternatively, the information may be signaled only for the luminance block. In this case, the reference region of the chrominance block may be determined dependently on the signaled information of the luminance block.

According to the above-described method, the reference region may be adaptively determined. However, there may exist a case in which the determined reference region is unavailable. Here, the unavailable case may mean a case in which the determined reference region is not-decoded, a case in which the determined reference region is located outside a picture, and the like. The non-decoded case may mean that the determined reference region belongs to the same parallel processing region as the luminance/chrominance block, or the determined reference region has a decoding order after the luminance/chrominance block.

In this way, when the determined reference region is unavailable, the reference region may be limited not to be used for inter-component reference-based prediction. For this, flag information regarding whether a corresponding reference region is used may be used. Alternatively, the unavailable reference area may be replaced with an available reference area. The available reference area may be an area adjacent to the unavailable reference area in a specific direction. The specific direction may be any one of left, right, top, bottom, or diagonal. The specific direction may be pre-promised to the encoding/decoding apparatus, or may be variably determined in consideration of the location of an unavailable reference region.

The number of sample lines belonging to the reference region may be one, two, or more. 6 , the upper reference area of the luminance block may include N _L horizontal lines, and the left reference area may include M _L vertical lines. The upper reference area of the color difference block may include N _C horizontal lines, and the left reference area may include M _C vertical lines. In this case, the number of sample lines (N _L , N _C ) of the upper reference region may be the same as the number of sample lines (M _L , M _C ) of the left reference region. Alternatively, any one of the number of sample lines (N _L , N _C ) of the upper reference region and the number of sample lines (M _L , M _C ) of the left reference region may be larger or smaller than the other.

The values of N _L , M _L , N _C , and M _C may be integers greater than or equal to zero. The values of N _L , M _L , N _C , and M _C may be set to a value pre-promised to the encoding/decoding apparatus, or may be variably determined based on the above-described encoding information. Alternatively, the information on the number of the sample lines may be encoded and signaled by the encoding apparatus, and the decoding apparatus determines the values of N _L , M _L , N _C , and M _C based on the signaled information. can

Meanwhile, a ratio between the number of sample lines included in the luminance reference region and the number of sample lines included in the chrominance reference region may be determined based on a color format. For example, when the color format is 4:2:0, the ratio (N _L :N _C or M _L :M _C ) between the number of sample lines included in the luminance reference region and the number of sample lines included in the chrominance reference region is It could be 2:1.

Based on the determined ratio, up-sampling or down-sampling may be performed on at least one of the luminance reference region and the chrominance reference region, and it is possible to match the ratio of the reference region between the luminance and the chrominance through the sampling process .

Also, regardless of the color format, the ratio of the reference region between the luminance and the chrominance may be 1:1. That is, the number of sample lines included in the chrominance reference region may be set dependently on the number of reference lines included in the luminance reference region (eg, N _L =N _C or M _L =M _C ). The embodiment related to the ratio may be equally/similarly applied to the ratio between the length of the luminance reference region and the length of the chrominance reference region.

As described above, the reference region may include a plurality of sample lines, and in this case, some samples mentioned in FIG. 5 may belong to the same sample line among the plurality of sample lines. Alternatively, at least one of the partial samples may belong to a sample line different from the other one.

Meanwhile, the shape of the block shown in FIGS. 6 and 7 is an NxN square, but this does not limit the size or shape of the block, and may have various sizes/shapes according to the above-described division type.

8 illustrates a method of determining a region of a luminance block used for reference between components of a chrominance block according to an embodiment to which the present invention is applied.

The encoding/decoding apparatus may determine a region (hereinafter, referred to as a luminance region) of a luminance block used for inter-component reference of the chrominance block. Accordingly, the luminance block in the above-described embodiment may be interpreted as a luminance block corresponding to the chrominance block or may be interpreted as the luminance region.

There may exist a case where one chrominance block corresponds to one luminance block (ie, luminance block:chrominance block=1:1). Here, the luminance/chrominance block may mean a block that is no longer divided. In this case, as shown in FIG. 5 , the luminance region of the present invention may be determined as a luminance block corresponding to the color difference block. Of course, the determined luminance area may be resized to correspond to the resolution of the color difference block.

Meanwhile, as shown in FIG. 8 , when one chrominance block corresponds to a luminance block composed of N sub-blocks according to at least one of the aforementioned division type or color format (that is, luminance block E _L : color difference Blocks A _C =N:1) may exist. In this case, the luminance area may be determined as a luminance block corresponding to the chrominance block, and may be resized to correspond to the resolution of the chrominance block. Alternatively, the region of the luminance block overlapping the chrominance block may be determined as the luminance region. Alternatively, when the luminance block: the chrominance block=N:1, the decoding apparatus may be restricted so that the aforementioned inter-component reference-based prediction is not performed.

Alternatively, when a chrominance block composed of M sub-blocks corresponds to a luminance block composed of N sub-blocks according to at least one of the aforementioned division type or color format (that is, luminance block:chrominance block=N:M ) may exist. In this case, the luminance region may be determined in consideration of the correspondence between the luminance block and the chrominance block, that is, the N:M correspondence. Alternatively, the region of the luminance block overlapping the chrominance block may be determined as the luminance region.

The determined luminance region may include at least one of an intra-mode coded block and an inter-mode coded block. When the luminance region includes blocks each coded in the intra/inter mode, it may be limited so that inter-component reference-based prediction is not performed. Alternatively, even when the luminance region includes blocks each coded in intra/inter mode, it is possible to calculate a compensation parameter using neighboring samples of the luminance region. Also, when the luminance region includes a block encoded in the inter mode, the reference region may be expanded as shown in FIG. 6 , and a detailed description thereof will be omitted. Alternatively, when the luminance region includes blocks each coded in the intra/inter mode, only neighboring samples of the blocks coded in the inter mode may be used as the luminance reference region. In this case, the color difference reference region may also be determined only from the region corresponding to the neighboring samples of the block encoded in the inter mode. Alternatively, when the luminance region includes blocks each encoded in the intra/inter mode, the encoding apparatus may encode and signal information specifying the luminance/chrominance reference region, and the decoding apparatus may perform luminance based on the information. /Specifies the color difference reference area. Alternatively, when the luminance block: the chrominance block = N: M, the decoding apparatus may be limited so that the aforementioned inter-component reference-based prediction is not performed.

The determination of the luminance region may be performed in consideration of at least one of division information of a luminance block, division information of a chrominance block, or a correspondence relationship between division information between a luminance block and a chrominance block. The partition information may include at least one of a width of a divided block, a height, a ratio of a width to a height, the number of samples included in the block, the number of sub-blocks included in the block, a shape of the sub-block, or a partition type can

The determination of the luminance region may be performed based on a comparison result between the division information of the luminance block and the division information of the chrominance block. For example, when the division information of the chrominance block is the same as the division information of the luminance block, the luminance region may be determined as a luminance block corresponding to the chrominance block. On the other hand, when the division information of the chrominance block is not the same as the division information of the luminance block, the luminance region may be determined as a partial region of the luminance block according to a predetermined rule or information signaled by an encoding device. The information may be information for specifying the luminance region.

Example methods of the present disclosure are expressed as a series of operations for clarity of description, but this is not intended to limit the order in which the steps are performed, and if necessary, each step may be performed simultaneously or in a different order. In order to implement the method according to the present disclosure, other steps may be included in addition to the illustrated steps, steps may be excluded from some steps, and/or other steps may be included except for some steps.

Various embodiments of the present disclosure do not list all possible combinations but are intended to describe representative aspects of the present disclosure, and matters 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), general purpose It may be implemented by a processor (general processor), a controller, a microcontroller, a microprocessor, and the like.

The scope of the present disclosure includes software or machine-executable instructions (eg, operating system, application, firmware, program, etc.) that cause an operation according to the method of various embodiments to be executed on a device or computer, and such software or and non-transitory computer-readable media in which instructions and the like are stored and executable on a device or computer.

Claims (13)

deriving a first predicted value of the chrominance block by using the samples of the luminance block;
calculating a compensation parameter based on a predetermined reference region;
deriving a second prediction value of the color difference block by applying the compensation parameter to the first prediction value; and
reconstructing the chrominance block based on a second predicted value of the chrominance block;
Calculating the compensation parameter includes determining the reference region referred to for calculating the compensation parameter,
the reference region includes a luminance reference region adjacent to the luminance block and a chrominance reference region adjacent to the chrominance block;
The luminance reference region includes a plurality of sample lines,
and the number of sample lines belonging to the luminance reference region is variably determined according to availability of the luminance reference region. delete According to claim 1,
The compensation parameter is calculated based on at least one of a representative value of the luminance reference region and a representative value of the chrominance reference region. 4. The method of claim 3,
The representative value of the color difference reference region is derived from any one of an average value, a minimum value, a maximum value, a mode, and an intermediate value of some samples belonging to the color difference reference region. According to claim 1,
The deriving of the first prediction value is selectively performed based on information indicating whether the color difference block is decoded through inter-component reference-based prediction. According to claim 1,
The color difference block is a first color difference block (Cr block),
A video signal processing method in which a second chrominance block (Cb block) is reconstructed using at least one of a sample of the luminance block and a sample of the first chrominance block. A first predicted value of the chrominance block is derived using a sample of the luminance block, a compensation parameter is calculated based on a predetermined reference region, and the compensation parameter is applied to the first predicted value to obtain a second predicted value of the chrominance block a prediction unit for inducing and
a restoration unit for reconstructing the color difference block based on a second predicted value of the color difference block;
The prediction unit determines the reference region referred to for calculating the compensation parameter,
the reference region includes a luminance reference region adjacent to the luminance block and a chrominance reference region adjacent to the chrominance block;
The luminance reference region includes a plurality of sample lines,
and the number of sample lines belonging to the luminance reference region is variably determined according to availability of the luminance reference region. delete 8. The method of claim 7,
The compensation parameter is calculated based on at least one of a representative value of the luminance reference region and a representative value of the chrominance reference region. 10. The method of claim 9,
The representative value of the color difference reference region is derived from any one of an average value, a minimum value, a maximum value, a mode, and a median value of some samples belonging to the color difference reference region. The method of claim 7, wherein the prediction unit,
A video signal processing apparatus for deriving the first prediction value based on information indicating whether the color difference block is decoded through inter-component reference-based prediction. 8. The method of claim 7,
The color difference block is a first color difference block (Cr block),
A second chrominance block (Cb block) is a video signal processing apparatus that is reconstructed using at least one of a sample of the luminance block and a sample of the first chrominance block. A computer-readable recording medium storing a bitstream, comprising:
The bitstream includes a residual block generated based on a second prediction value of the chrominance block,
The second predicted value of the chrominance block is derived by applying a compensation parameter to the first predicted value of the chrominance block,
The compensation parameter is calculated based on a predetermined reference region,
The first predicted value of the chrominance block is derived using samples of the luminance block,
the reference region includes a luminance reference region adjacent to the luminance block and a chrominance reference region adjacent to the chrominance block;
The luminance reference region includes a plurality of sample lines,
The number of sample lines belonging to the luminance reference region is variably determined according to availability of the luminance reference region.

Images