Video encoding method and apparatus using chroma component prediction based on luma component

Abstract

The present embodiment provides a video encoding method and apparatus using chroma component prediction based on a luma component. In this embodiment, an image decoding device derives a corresponding luma block of a current chroma block based on a color format. An image decoding apparatus obtains a luma component pre-recovery region for a corresponding luma block and a chrominance component pre-recovery region for a current chrominance block based on a block segmentation structure of a luma component and a chrominance component and prediction information of the corresponding luma block. The image decoding apparatus performs modeling of a relationship between samples within a luma component pre-recovery region and samples within a chroma component pre-recovery region, and then generates a prediction block of a current chroma block from samples of a corresponding luma block by using the modeled relationship.

Description

Technical Field

[0001] The present disclosure relates to a video encoding method and apparatus using chrominance component prediction based on luma components. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Since video data has a large amount of data compared to audio or still image data, without a process for compression, the video data requires a large amount of hardware resources (including memory) to store or transmit the video data.

[0004] Thus, encoders are generally used to compress and store or transmit video data. Decoders receive compressed video data, decompress the received compressed video data, and play the decompressed video data. Video compression technologies include H.264 / Advanced Video Coding (AVC), High Efficiency Video Coding (HEVC), and Versatile Video Coding (VVC), which have improved coding efficiency of about 30% or more compared to HEVC.

[0005] However, as image size, resolution and frame rate gradually increase, the amount of data to be encoded also increases. Thus, a new compression technology that provides higher encoding efficiency and improved image enhancement effect than existing compression technologies is needed.

[0006] In VVC, intra-frame prediction of chroma components can be performed based on plane, DC, horizontal, vertical mode, direct mode (DM) or cross-component linear model (CCLM) mode. DM predicts the current chroma block by using the prediction mode used in the prediction process of the luminance block corresponding to the current chroma block. The CCLM mode is a new prediction mode adopted and added to VVC, which linearly models the relationship between the reconstructed adjacent sample values ​​of the current chroma block and the reconstructed adjacent sample values ​​of the corresponding luminance block (at the position corresponding to the current chroma block). Using the obtained linear model, the CCLM mode transforms the values ​​in the reconstructed area of ​​the corresponding luminance block to predict the current chroma component. The CCLM mode includes three modes, each of which can obtain a linear model by using samples in the reconstructed area at the top of the current block, the upper left of the current block, or the left side of the current block. In order to indicate one of the three modes, the encoder can send the relevant index to the decoder with a signal.

[0007] In the intra prediction of the chrominance component as described above, the reconstructed adjacent samples of the current chrominance block and / or the corresponding luminance block are used. Therefore, in order to increase video coding efficiency and enhance video quality, it is necessary to consider the effective use of the adjacent reconstructed samples of the current chrominance block and / or the corresponding luminance block. Summary of the invention

[0008] [Technical issues]

[0009] The present disclosure seeks to provide a video encoding method and apparatus that, when predicting a chrominance component after prediction and reconstruction of a luminance component of a current block, reconstructs a current chrominance block by using prediction information of a corresponding luminance block at a position corresponding to the current chrominance block, reconstructed sample values ​​of the corresponding luminance block, and neighboring reconstructed sample values ​​of the current chrominance block.

[0010] [Technical solution]

[0011] At least one aspect of the present invention provides a method for intra-frame prediction of a current chroma block performed by a video decoding device. The method includes obtaining a corresponding luminance block corresponding to the current chroma block based on a color format representing the correspondence between pixels of the corresponding luminance block and pixels of the current chroma block. The method also includes: based on the block segmentation structure of the luminance component and the chroma component and the prediction information of the corresponding luminance block, obtaining a reconstruction area for the luminance component of the corresponding luminance block, and obtaining a reconstruction area for the chroma component of the current chroma block. The method also includes modeling the relationship between samples in the reconstruction area of ​​the luminance component and samples in the reconstruction area of ​​the chroma component. The method also includes generating a prediction block of the current chroma block from samples in the corresponding luminance block by using the modeled relationship.

[0012] Another aspect of the present invention provides a method for intra-frame prediction of a current chroma block performed by a video encoding device. The method includes obtaining a corresponding luminance block corresponding to the current chroma block based on a color format representing the correspondence between pixels of the corresponding luminance block and pixels of the current chroma block. The method also includes obtaining a reconstruction area for the luminance component of the corresponding luminance block based on a block segmentation structure of the luminance component and the chroma component and prediction information of the corresponding luminance block, and obtaining a reconstruction area for the chroma component of the current chroma block. The method also includes modeling the relationship between samples in the reconstruction area of ​​the luminance component and samples in the reconstruction area of ​​the chroma component. The method also includes generating a first prediction block of the current chroma block from samples in the corresponding luminance block by using the modeled relationship.

[0013] Another aspect of the present invention provides a computer-readable recording medium storing a bitstream generated by a video encoding method. The video encoding method includes: obtaining a corresponding luminance block corresponding to the current chrominance block based on a color format representing the correspondence between pixels of the corresponding luminance block and pixels of the current chrominance block. The video encoding method also includes: obtaining a reconstruction area for the luminance component of the corresponding luminance block based on a block segmentation structure of the luminance component and the chrominance component and prediction information of the corresponding luminance block, and obtaining a reconstruction area for the chrominance component of the current chrominance block. The video encoding method also includes modeling the relationship between samples in the reconstruction area of ​​the luminance component and samples in the reconstruction area of ​​the chrominance component. The video encoding method also includes generating a prediction block of the current chrominance block from samples in the corresponding luminance block by using the modeled relationship.

[0014] [Beneficial Effects]

[0015] As described above, the present disclosure provides a video encoding method and device for reconstructing a current chrominance block by using prediction information of a corresponding luminance block corresponding to the current chrominance block, a reconstructed sample value of the corresponding luminance block, and a neighboring reconstructed sample value of the current chrominance block. Thus, the video encoding method and device improve video encoding efficiency and enhance video quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a block diagram of a video encoding device that may implement the techniques of this disclosure.

[0017] Figure 2 A method for partitioning a block using a quadtree plus binary tree ternary tree (QTBTTT) structure is described.

[0018] Figure 3a and 3b Multiple intra prediction modes are shown including a wide-angle intra prediction mode.

[0019] Figure 4 Shows the neighboring blocks of the current block.

[0020] Figure 5 is a block diagram of a video decoding device that may implement the techniques of this disclosure.

[0021] Figure 6 is a block diagram detailing a portion of a video decoding device according to at least one embodiment of the present disclosure.

[0022] Figures 7a to 7c is a diagram illustrating the location of samples used for modeling according to at least one embodiment of the present disclosure.

[0023] Figure 8 is a resulting diagram showing the locations of samples used for modeling in accordance with at least one embodiment of the present disclosure.

[0024] Figure 9a and 9b is a resulting diagram illustrating locations of samples used for modeling according to another embodiment of the present disclosure.

[0025] Fig.10 and 11 is an implicitly derived diagram showing the positions of samples used for modeling according to other embodiments of the present disclosure.

[0026] Fig.12a and 12b is an implicitly derived diagram illustrating the locations of samples used for modeling according to yet another embodiment of the present invention.

[0027] Fig.13a and 13b is an implicitly derived diagram illustrating the locations of samples used for modeling according to yet another embodiment of the present invention.

[0028] Fig.14 is a resulting diagram showing reconstructed reference lines or regions of chroma components according to at least one embodiment of the present disclosure.

[0029] Fig.15a and 15b is an implicitly derived diagram illustrating reconstructed reference lines or regions of chroma components in accordance with at least one embodiment of the present invention.

[0030] Fig.16 is a diagram showing an implicit derivation of a reconstructed reference line or region of a chroma component according to another embodiment of the present disclosure.

[0031] Fig.17 The present invention is a flowchart of a method for performing intra-frame prediction on a current block, performed by a video encoding apparatus according to at least one embodiment of the present invention.

[0032] Fig.18 The present invention is a flowchart of a method for performing intra-frame prediction on a current block, performed by a video decoding apparatus according to at least one embodiment of the present invention. DETAILED DESCRIPTION

[0033] Hereinafter, some embodiments of the present disclosure are described in detail with reference to the accompanying drawings. In the following description, the same reference numerals represent the same elements, although the elements are shown in different drawings. In addition, in the following description of some embodiments, for the purpose of clarity and brevity, detailed descriptions of related known components and functions may be omitted when it is considered to obscure the subject matter of the present disclosure.

[0034] Figure 1 is a block diagram of a video encoding device that can implement the technology of the present disclosure. Figure 1A diagram of a video encoding device and components of the device is described.

[0035] The encoding device may include a picture separator 110, a predictor 120, a subtractor 130, a transformer 140, a quantizer 145, a rearrangement unit 150, an entropy encoder 155, an inverse quantizer 160, an inverse transformer 165, an adder 170, a loop filter unit 180 and a memory 190.

[0036] Each component of the encoding device can be implemented as hardware or software or as a combination of hardware and software. In addition, the function of each component can be implemented as software, and a microprocessor can also be implemented to execute the function of the software corresponding to each component.

[0037] A video is composed of one or more sequences including multiple pictures. Each picture is divided into multiple regions, and encoding is performed on each region. For example, a picture is split into one or more tiles or / and slices. Here, one or more tiles can be defined as tile groups. Each tile or / and slice is split into one or more coding tree units (CTUs). In addition, each CTU is split into one or more coding units (CUs) through a tree structure. The information applied to each coding unit (CU) is encoded as the syntax of the CU, and the information commonly applied to the CU contained in a CTU is encoded as the syntax of the CTU. In addition, the information commonly applied to all blocks in a slice is encoded as the syntax of the slice header, and the information applied to all blocks constituting one or more pictures is encoded as a picture parameter set (PPS) or a picture header. In addition, the information commonly referenced by multiple pictures is encoded into a sequence parameter set (SPS). In addition, the information commonly referenced by one or more SPSs is encoded into a video parameter set (VPS). Further, the information commonly applied to a tile or tile group can also be encoded as the syntax of the tile or tile group header. The syntax included in the SPS, PPS, slice header, tile, or tile group header may be referred to as a high-level syntax.

[0038] The picture partitioner 110 determines the size of a coding tree unit (CTU). Information on the size of the CTU (CTU size) is encoded as a syntax of an SPS or a PPS and delivered to a video decoding device.

[0039] The picture divider 110 divides each picture constituting a video into a plurality of coding tree units (CTUs) having a predetermined size, and then recursively divides the CTUs by using a tree structure. A leaf node in the tree structure becomes a coding unit (CU), which is a basic unit of encoding.

[0040] The tree structure may be a quadtree (QT), in which a higher node (or parent node) is divided into four lower nodes (or child nodes) of the same size. The tree structure may also be a binary tree (BT), in which a higher node is divided into two lower nodes. The tree structure may also be a ternary tree (TT), in which a higher node is divided into three lower nodes at a ratio of 1:2:1. The tree structure may also be a structure in which two or more of the QT structure, the BT structure, and the TT structure are mixed. For example, a quadtree plus binary tree (QTBT) structure may be used or a quadtree plus binary tree ternary tree (QTBTTT) structure may be used. Here, a binary tree ternary tree (BTTT) is added to the tree structure to be referred to as a multi-type tree (MTT).

[0041] Figure 2 is a diagram for describing a method of partitioning a block by using a QTBTTT structure.

[0042] like Figure 2 As shown, the CTU can be first split into a QT structure. The quadtree partitioning can be recursive until the size of the partitioned block reaches the minimum block size (MinQTSize) of the leaf node allowed in QT. The first flag (QT_split_flag) indicating whether each node of the QT structure is divided into four nodes of the lower layer is encoded by the entropy encoder 155 and transmitted to the video decoding device. When the leaf node of QT is not larger than the maximum block size (MaxBTSize) of the root node allowed in BT, the leaf node can be further divided into at least one of the BT structure or the TT structure. There may be multiple partitioning directions in the BT structure and / or the TT structure. For example, there may be two directions, namely, the direction in which the blocks of the corresponding node are horizontally divided and the direction in which the blocks of the corresponding node are vertically divided. As Figure 2 As shown, when MTT splitting starts, a second flag (mtt_split_flag) indicating whether a node is split and a flag additionally indicating a split direction (vertical or horizontal) and / or a flag indicating a split type (binary or ternary) if the node is split are encoded by the entropy encoder 155 and signaled to the video decoding device.

[0043] Alternatively, before encoding the first flag (QT_split_flag) indicating whether each node is split into four nodes of the lower layer, a CU split flag (split_cu_flag) indicating whether the node is split may also be encoded. When the value of the CU split flag (split_cu_flag) indicates that each node is not split, the block of the corresponding node becomes a leaf node in the split tree structure and becomes a CU as a basic unit of encoding. When the value of the CU split flag (split_cu_flag) indicates that each node is split, the video encoding device first starts encoding the first flag through the above scheme.

[0044] When QTBT is used as another example of a tree structure, there may be two types, namely, a type in which the block of the corresponding node is horizontally divided into two blocks of the same size (i.e., symmetrical horizontal division) and a type in which the block of the corresponding node is vertically divided into two blocks of the same size (i.e., symmetrical vertical division). A split flag (split_flag) indicating whether each node of the BT structure is split into blocks of the lower layer and split type information indicating the split type are encoded by the entropy encoder 155 and delivered to the video decoding device. At the same time, a type in which the block of the corresponding node is split into two blocks that are asymmetric to each other may be presented in addition. The asymmetric form may include a form in which the block of the corresponding node is divided into two rectangular blocks having a size ratio of 1:3, or may also include a form in which the block of the corresponding node is divided in a diagonal direction.

[0045] A CU may have different sizes depending on the QTBT or QTBTTT split from a CTU. Hereinafter, a block corresponding to a CU to be encoded or decoded (i.e., a leaf node of a QTBTTT) is referred to as a "current block". Due to the QTBTTT split, the shape of the current block may be a rectangular shape in addition to a square shape.

[0046] The predictor 120 predicts the current block to generate a predicted block. The predictor 120 includes an intra predictor 122 and an inter predictor 124.

[0047] In general, each of the current blocks in a picture may be predictively encoded. Typically, the prediction of the current block may be performed using intra-prediction techniques (using data from the picture including the current block) or inter-prediction techniques (using data from a picture coded before the picture including the current block). Inter-prediction includes both unidirectional prediction and bidirectional prediction.

[0048] The intra-frame predictor 122 predicts pixels in the current block by using pixels (reference pixels) located on neighbors of the current block in the current picture including the current block. There are multiple intra-frame prediction modes according to the prediction direction. For example, Figure 3a As shown in , the plurality of intra prediction modes may include 2 non-directional modes including a planar mode and a DC mode, and may include 65 directional modes. Neighboring pixels and an arithmetic equation to be used are differently defined according to each prediction mode.

[0049] In order to perform effective directional prediction on the current block having a rectangular shape, a directional mode (#67 to #80, intra prediction mode #-1 to #-14) as illustrated by the dotted arrows in FIG. 3B may be additionally used. The directional mode may be referred to as a "wide-angle intra prediction mode". In FIG. 3B, the arrow indicates the corresponding reference sample used for prediction and does not indicate the prediction direction. The prediction direction is opposite to the direction indicated by the arrow. When the current block has a rectangular shape, the wide-angle intra prediction mode is a mode in which prediction is performed in the opposite direction to the specific directional mode without additional bit transmission. In this case, in the wide-angle intra prediction mode, some wide-angle intra prediction modes available for the current block may be determined by the ratio of the width and height of the current block having a rectangular shape. For example, when the current block has a rectangular shape with a height less than the width, a wide-angle intra prediction mode (intra prediction mode #67 to #80) with an angle less than 45 degrees is available. When the current block has a rectangular shape with a width greater than the height, a wide-angle intra prediction mode with an angle greater than -135 degrees may be used.

[0050] The intra-frame predictor 122 may determine an intra-frame prediction to be used for encoding the current block. In some embodiments, the intra-frame predictor 122 may encode the current block by using a plurality of intra-frame prediction modes, and may further select an appropriate intra-frame prediction mode to be used from a test mode. For example, the intra-frame predictor 122 may calculate a rate-distortion value by using a rate-distortion analysis for a plurality of tested intra-frame prediction modes, and may further select an intra-frame prediction mode having the best rate-distortion characteristics in the test mode.

[0051] The intra predictor 122 selects an intra prediction mode from among a plurality of intra prediction modes and predicts the current block by using neighboring pixels (reference pixels) and an arithmetic equation determined according to the selected intra prediction mode. Information on the selected intra prediction mode is encoded by the entropy encoder 155 and delivered to the video decoding apparatus.

[0052] The inter-frame predictor 124 generates a prediction block for the current block by using a motion compensation process. The inter-frame predictor 124 searches for a block most similar to the current block in a reference picture that is encoded and decoded earlier than the current picture, and generates a prediction block for the current block by using the searched block. In addition, a motion vector (MV) is generated, which corresponds to the displacement between the current block in the current picture and the prediction block in the reference picture. Typically, motion estimation is performed on the luminance component, and the motion vector calculated based on the luminance component is used for both the luminance component and the chrominance component. Motion information including information about the reference picture and information about the motion vector used to predict the current block is encoded by the entropy encoder 155 and delivered to the video decoding device.

[0053] The inter-frame predictor 124 may also perform interpolation on a reference picture or a reference block in order to increase the accuracy of the prediction. In other words, the subsamples between two consecutive integer samples are interpolated by applying the filter coefficients to a plurality of consecutive integer samples including two integer samples. When the process of searching for the block most similar to the current block is performed for the interpolated reference picture, the decimal unit precision may be used instead of the integer sample unit precision for the motion vector representation. The precision or resolution of the motion vector may be set differently for each target region to be encoded (e.g., units such as slices, tiles, CTUs, CUs, etc.). When this adaptive motion vector resolution (AMVR) is applied, information about the motion vector resolution to be applied to each target region should be signaled for each target region. For example, when the target region is a CU, information about the motion vector resolution applied to each CU is signaled. The information about the motion vector resolution may be information representing the precision of the motion vector difference to be described below.

[0054] Meanwhile, the inter-frame predictor 124 may perform inter-frame prediction by using bidirectional prediction. In the case of bidirectional prediction, two reference pictures and two motion vectors representing the block position most similar to the current block in each reference picture are used. The inter-frame predictor 124 selects a first reference picture and a second reference picture from reference picture list 0 (RefPicList0) and reference picture list 1 (RefPicList1), respectively. The inter-frame predictor 124 also searches for a block most similar to the current block in the corresponding reference picture to generate a first reference block and a second reference block. In addition, a prediction block of the current block is generated by averaging or weighted averaging the first reference block and the second reference block. In addition, motion information including information about two reference pictures for predicting the current block and including information about two motion vectors is delivered to the entropy encoder 155. Here, the reference picture list 0 may be composed of pictures before the current picture in the display order among the pre-reconstructed pictures, and the reference picture list 1 may be composed of pictures after the current picture in the display order among the pre-reconstructed pictures. However, although not particularly limited thereto, a pre-reconstructed picture after the current picture in the display order may be additionally included in the reference picture list 0. Conversely, a pre-reconstructed picture before the current picture may also be additionally included in the reference picture list 1.

[0055] In order to minimize the number of bits consumed for encoding motion information, various methods may be used.

[0056] For example, when the reference picture and motion vector of the current block are the same as those of the neighboring block, information capable of identifying the neighboring block is encoded to deliver the motion information of the current block to the video decoding device. This method is called merge mode.

[0057] In the merge mode, the inter predictor 124 selects a predetermined number of merge candidate blocks (hereinafter, referred to as “merge candidates”) from neighboring blocks of the current block.

[0058] As a neighboring block for obtaining a merge candidate, such as Figure 4 As illustrated in the figure, all or some of the left block A0, the lower left block A1, the upper block B0, the upper right block B1, and the upper left block B2 adjacent to the current block in the current picture can be used. Further, blocks other than the current picture where the current block is located, which are located in a reference picture (which may be the same as or different from the reference picture used to predict the current block), can also be used as merge candidates. For example, a block located at the same location as the current block or a block adjacent to the block located at the same location in the reference picture can be used as a merge candidate in addition. If the number of merge candidates selected by the method described above is less than the preset number, a zero vector is added to the merge candidate.

[0059] The inter-frame predictor 124 configures a merge list including a predetermined number of merge candidates by using adjacent blocks. A merge candidate to be used as motion information of the current block is selected from the merge candidates included in the merge list, and merge index information for identifying the selected candidate is generated. The generated merge index information is encoded by the entropy encoder 155 and delivered to the video decoding device.

[0060] Merge skip mode is a special case of merge mode. After quantization, when all transform coefficients for entropy coding are close to zero, only the neighbor block selection information is transmitted without the residual signal. By using merge skip mode, relatively high coding efficiency can be achieved for pictures with slight motion, still pictures, screen content pictures, etc.

[0061] Hereinafter, the merge mode and the merge skip mode are collectively referred to as the merge / skip mode.

[0062] Another method for encoding motion information is the Advanced Motion Vector Prediction (AMVP) mode.

[0063] In the AMVP mode, the inter-frame predictor 124 obtains a motion vector predictor candidate for a motion vector of the current block by using the neighboring blocks of the current block. As the neighboring blocks for obtaining the motion vector predictor candidate, the same as in Figure 4All or some of the left block A0, lower left block A1, upper block B0, upper right block B1 and upper left block B2 adjacent to the current block in the current picture illustrated in the figure. In addition, blocks other than the current picture where the current block is located, which are located in a reference picture (which may be the same as or different from the reference picture used to predict the current block), may also be used as adjacent blocks for obtaining motion vector predictor candidates. For example, blocks co-located with the current block in the reference picture or blocks adjacent to the co-located blocks may be used. If the number of motion vector candidates selected by the above method is less than the preset number, a zero vector is added to the motion vector candidates.

[0064] The inter predictor 124 obtains motion vector predictor candidates by using motion vectors of neighboring blocks, and determines a motion vector predictor for a motion vector of a current block by using the motion vector predictor candidates. In addition, a motion vector difference is calculated by subtracting the motion vector predictor from the motion vector of the current block.

[0065] The motion vector predictor can be obtained by applying a predefined function (e.g., center value and average value calculation, etc.) to the motion vector predictor candidate. In this case, the video decoding device also knows the predefined function. In addition, since the neighboring blocks used to obtain the motion vector predictor candidate are blocks for which encoding and decoding have been completed, the video decoding device may also already know the motion vectors of the neighboring blocks. Therefore, the video encoding device does not need to encode information for identifying the motion vector predictor candidate. Thus, in this case, information about the motion vector difference and information about the reference picture used to predict the current block are encoded.

[0066] Meanwhile, the motion vector predictor may also be determined by selecting any one of the motion vector predictor candidates. In this case, information for identifying the selected motion vector predictor candidate is additionally encoded jointly with information about the motion vector difference and information about the reference picture used to predict the current block.

[0067] The subtractor 130 generates a residual block by subtracting a prediction block generated by the intra predictor 122 or the inter predictor 124 from the current block.

[0068] The transformer 140 converts the residual signal in the residual block having the pixel value in the spatial domain into a transform coefficient in the frequency domain. The transformer 140 may transform the residual signal in the residual block by using the total size of the residual block as a transform unit, or may further divide the residual block into a plurality of sub-blocks, and may perform the transform by using the sub-block as a transform unit. Optionally, the residual block is divided into two sub-blocks, namely a transform region and a non-transform region, so as to transform the residual signal using only the transform region sub-block as a transform unit. Here, the transform region sub-block may be one of two rectangular blocks having a size ratio of 1:1 based on the horizontal axis (or vertical axis). In this case, the flag (cu_sbt_flag) indicates that only the sub-block is transformed, and the directional (vertical / horizontal) information (cu_sbt_horizontal_flag) and / or the position information (cu_sbt_pos_flag) are encoded by the entropy encoder 155 and signaled to the video decoding device. In addition, the size of the transform region sub-block may have a size ratio of 1:3 based on the horizontal axis (or vertical axis). In this case, a flag (cu_sbt_quad_flag) for dividing the corresponding division is additionally encoded by the entropy encoder 155 and signaled to the video decoding apparatus.

[0069] Meanwhile, the transformer 140 may perform transformation on the residual block separately in the horizontal direction and the vertical direction. For the transformation, different types of transformation functions or transformation matrices may be used. For example, a pair of transformation functions for horizontal transformation and vertical transformation may be defined as a multiple transformation set (MTS). The transformer 140 may select a transformation function pair with the highest transformation efficiency in the MTS, and may transform the residual block in each of the horizontal and vertical directions. Information (mts_idx) of the transformation function pair in the MTS is encoded by the entropy encoder 155 and notified to the video decoding device with a signal.

[0070] The quantizer 145 quantizes the transform coefficients output from the transformer 140 using the quantization parameter and outputs the quantized transform coefficients to the entropy encoder 155. The quantizer 145 may also immediately quantize the relevant residual block without transforming any block or frame. The quantizer 145 may also apply different quantization coefficients (scaling values) according to the position of the transform coefficient in the transform block. The quantization matrix applied to the quantized transform coefficients arranged in 2 dimensions may be encoded and signaled to the video decoding device.

[0071] The rearrangement unit 150 may perform rearrangement of coefficient values ​​for the quantized residual value.

[0072] The rearrangement unit 150 may change the 2D coefficient array into a 1D coefficient sequence by using coefficient scanning. For example, the rearrangement unit 150 may output an ID coefficient sequence by scanning the DC coefficient into a high frequency domain coefficient using a zigzag scan or a diagonal scan. Depending on the size of the transform unit and the intra prediction mode, a vertical scan that scans the 2D coefficient array in the column direction and a horizontal scan that scans the 2D block type coefficients in the row direction may also be used instead of the zigzag scan. In other words, depending on the size of the transform unit and the intra prediction mode, the scanning method to be used may be determined among zigzag scanning, diagonal scanning, vertical scanning, and horizontal scanning.

[0073] The entropy encoder 155 generates a bitstream by encoding the sequence of ID-quantized transform coefficients output from the rearrangement unit 150 using various encoding schemes including context-based adaptive binary arithmetic coding (CABAC), exponential Golomb, and the like.

[0074] In addition, the entropy encoder 155 encodes information related to block partitioning (such as CTU size, CTU partition flag, QT partition flag, MTT partition type, MTT partition direction, etc.) to allow the video decoding device to equally partition the block to the video encoding device. In addition, the entropy encoder 155 encodes information about the prediction type indicating whether the current block is encoded by intra-frame prediction or inter-frame prediction. The entropy encoder 155 encodes intra-frame prediction information (i.e., information about the intra-frame prediction mode) or inter-frame prediction information (in the case of merge mode, merge index, and in the case of AMVP mode, information about reference picture index and motion vector difference) according to the prediction type. In addition, the entropy encoder 155 encodes information related to quantization (i.e., information about quantization parameters and information about quantization matrices).

[0075] The inverse quantizer 160 dequantizes the quantized transform coefficient output from the quantizer 145 to generate a transform coefficient. The inverse transformer 165 transforms the transform coefficient output from the inverse quantizer 160 from the frequency domain to the spatial domain to reconstruct a residual block.

[0076] The adder 170 reconstructs the current block by adding the reconstructed residual block and the prediction block generated by the predictor 120. When intra prediction is performed on a next sequential block, pixels in the reconstructed current block may be used as reference pixels.

[0077] The loop filter unit 180 performs filtering on the reconstructed pixels in order to reduce blocking artifacts, ringing artifacts, blurring artifacts, etc. occurring due to block-based prediction and transform / quantization. The loop filter unit 180 as a loop filter may include all or some of a deblocking filter 182, a sample adaptive offset (SAO) filter 184, and an adaptive loop filter (ALF) 186.

[0078] The deblocking filter 182 filters the boundaries between the reconstructed blocks to remove the block effects that occur due to block unit encoding / decoding, and the SAO filter 184 and the ALF 186 perform additional filtering for the deblocked filtered video. The SAO filter 184 and the ALF 186 are filters for compensating the difference between the reconstructed pixels and the original pixels, which occurs due to lossy encoding. The SAO filter 184 applies an offset as a CTU unit to enhance subjective picture quality and coding efficiency. On the other hand, the ALF 186 performs block unit filtering and applies different filters to compensate for distortion by dividing the boundaries of the corresponding blocks and the degree of variation. Information about the filter coefficients to be used for the ALF can be encoded and notified to the video decoding device with a signal.

[0079] The reconstructed blocks filtered by the deblocking filter 182, the SAO filter 184, and the ALF 186 are stored in the memory 190. When all blocks in one picture are reconstructed, the reconstructed picture can be used as a reference picture for inter-frame prediction of blocks in a picture to be encoded later.

[0080] The video encoding device may store a bit stream of encoded video data in a non-transitory storage medium, or transmit the bit stream to a video decoding device through a communication network.

[0081] Figure 5 is a functional block diagram of a video decoding device that can implement the techniques of the present invention. Figure 5 , describing a video decoding apparatus and components of the apparatus.

[0082] The video decoding device may include an entropy decoder 510 , a rearrangement unit 515 , an inverse quantizer 520 , an inverse transformer 530 , a predictor 540 , an adder 550 , a loop filter unit 560 , and a memory 570 .

[0083] and Figure 1 Similar to the video encoding device of the present invention, each component of the video decoding device can be implemented as hardware or software or as a combination of hardware and software. In addition, the function of each component can be implemented as software, and a microprocessor can also be implemented to execute the function of the software corresponding to each component.

[0084] The entropy decoder 510 extracts information related to block partitioning by decoding a bitstream generated by a video encoding apparatus to determine a current block to be decoded, and extracts prediction information required to reconstruct the current block and information about a residual signal.

[0085] The entropy decoder 510 determines the size of the CTU by extracting information about the CTU size from a sequence parameter set (SPS) or a picture parameter set (PPS), and divides the picture into CTUs of the determined size. In addition, the CTU is determined to be the highest level of the tree structure, that is, the root node, and the partition information of the CTU can be extracted to partition the CTU using the tree structure.

[0086] For example, when a CTU is divided using a QTBTTT structure, a first flag (QT_split_flag) related to the division of the QT is first extracted to divide each node into four nodes of the lower layer. In addition, for a node corresponding to a leaf node of the QT, a second flag (mtt_split_flag) related to the division of the MTT, a division direction (vertical / horizontal) and / or a division type (binary / ternary) are extracted to divide the corresponding leaf node into the MTT structure. As a result, each node below the leaf node of the QT is recursively split into a BT or TT structure.

[0087] As another embodiment, when a CTU is divided by using a QTBTTT structure, a CU split flag (split_cu_flag) indicating whether the CU is divided is extracted. When the corresponding block is divided, a first flag (QT_split_flag) may also be extracted. During the splitting process, for each node, 0 or more recursive MTT splits may occur after 0 or more recursive QT splits. For example, for a CTU, MTT splitting may occur immediately, or conversely, only multiple QT splits may occur.

[0088] For another example, when the CTU is split using the QTBT structure, the first flag (QT_split_flag) related to the splitting of the QT is extracted to split each node into four nodes of the lower layer. In addition, the split flag (split_flag) indicating whether the node corresponding to the leaf node of the QT is further split into BTs and the split direction information are extracted.

[0089] Meanwhile, when the entropy decoder 510 determines the current block to be decoded by using the partitioning of the tree structure, the entropy decoder 510 extracts information about the prediction type indicating whether the current block is intra-predicted or inter-predicted. When the prediction type information indicates intra-prediction, the entropy decoder 510 extracts syntax elements of intra-prediction information (intra-prediction mode) for the current block. When the prediction type information indicates inter-prediction, the entropy decoder 510 extracts information representing syntax elements for inter-prediction information (i.e., motion vectors and reference pictures referenced by motion vectors).

[0090] Furthermore, the entropy decoder 510 extracts quantization-related information and extracts information on a quantized transform coefficient of the current block as information on a residual signal.

[0091] The rearrangement unit 515 may change the sequence of 1D quantized transform coefficients entropy-decoded by the entropy decoder 510 into a 2D coefficient array (ie, block) again in the reverse order of the coefficient scanning order performed by the video encoding device.

[0092] The inverse quantizer 520 dequantizes the quantized transform coefficients and dequantizes the quantized transform coefficients by using quantization parameters. The inverse quantizer 520 may also apply different quantization coefficients (scaling values) to the quantized transform coefficients arranged in 2D. The inverse quantizer 520 may perform inverse quantization by applying a matrix (scaling value) of quantization coefficients from a video encoding device to a 2D array of quantized transform coefficients.

[0093] The inverse transformer 530 generates a residual block for the current block by reconstructing a residual signal by inversely transforming the dequantized transform coefficients from the frequency domain into the spatial domain.

[0094] In addition, when the inverse transformer 530 inversely transforms a partial region (sub-block) of the transform block, the inverse transformer 530 extracts a flag (cu_sbt_flag) that only the sub-block of the transform block is transformed, direction (vertical / horizontal) information (cu_sbt_horizontal_flag) of the sub-block, and / or position information (cu_sbt_pos_flag) of the sub-block. The inverse transformer 530 also inversely transforms the transform coefficient of the corresponding sub-block from the frequency domain to the spatial domain to reconstruct the residual signal and fills the region that is not inversely transformed with a value of "0" as the residual signal to generate a final residual block for the current block.

[0095] In addition, when MTS is applied, the inverse transformer 530 determines a transform index or a transform matrix applied in each of the horizontal and vertical directions by using MTS information (mts_idx) signaled from the video encoding device. The inverse transformer 530 also performs inverse transform on the transform coefficients in the transform block in the horizontal and vertical directions by using the determined transform function.

[0096] The predictor 540 may include an intra predictor 542 and an inter predictor 544. The intra predictor 542 is activated when the prediction type of the current block is intra prediction, and the inter predictor 544 is activated when the prediction type of the current block is inter prediction.

[0097] The intra predictor 542 determines an intra prediction mode of a current block among a plurality of intra prediction modes according to a syntax element of the intra prediction mode extracted from the entropy decoder 510. The intra predictor 542 also predicts the current block by using neighboring reference pixels of the current block according to the intra prediction mode.

[0098] The inter predictor 544 determines a motion vector of a current block and a reference picture to which the motion vector refers by using a syntax element for the inter prediction mode extracted from the entropy decoder 510 .

[0099] The adder 550 reconstructs the current block by adding the residual block output from the inverse transformer 530 and the prediction block output from the inter predictor 544 or the intra predictor 542. When intra prediction is performed on a block to be decoded later, pixels within the reconstructed current block are used as reference pixels.

[0100] The loop filter unit 560 as a loop filter may include a deblocking filter 562, an SAO filter 564, and an ALF 566. The deblocking filter 562 performs deblocking filtering on the boundary between the reconstructed blocks in order to remove the block effect that occurs due to block unit decoding. The SAO filter 564 and the ALF 566 perform additional filtering on the reconstructed blocks after deblocking filtering in order to compensate for the difference between the reconstructed pixels and the original pixels that occurs due to lossy encoding. The filter coefficients of the ALF are determined by using information about the filter coefficients decoded from the bitstream.

[0101] The reconstructed blocks filtered by the deblocking filter 562, the SAO filter 564, and the ALF 566 are stored in the memory 570. When all blocks in one picture are reconstructed, the reconstructed picture can be used as a reference picture for inter-frame prediction of blocks in a picture to be encoded later.

[0102] In some embodiments, the present invention relates to encoding and decoding a video image as described above. More specifically, the present disclosure provides a video encoding method and apparatus for reconstructing a current chrominance block by using prediction information of a luminance block at a position corresponding to the current chrominance block, reconstructed sample values ​​of the luminance block at the corresponding position, and adjacent reconstructed sample values ​​of the current chrominance block.

[0103] The following embodiments may be performed by the intra-frame predictor 122 in the video encoding apparatus. The following embodiments may also be performed by the intra-frame predictor 542 in the video decoding apparatus.

[0104] The video encoding device in the encoding of the current block may generate signaling information associated with the present embodiment in terms of optimizing rate distortion. The video encoding device may encode the signaling information using the entropy encoder 155 and transmit the encoded signaling information to the video decoding device. The video decoding device may decode the signaling information associated with the decoding of the current block from the bitstream using the entropy decoder 510.

[0105] In the following description, the term 'target block' may be used interchangeably with a current block or a coding unit (CU), or may refer to some regions of a coding unit.

[0106] In addition, a flag value of true indicates when the flag is set to 1. In addition, a flag value of false indicates when the flag is set to 0.

[0107] I. Intra-frame prediction of chroma components

[0108] Several techniques were introduced to improve coding efficiency by using intra prediction.

[0109] In the VVC technology, the intra prediction mode of the luminance block has 65 subdivided directional modes (ie, 2 to 66) in addition to the non-directional mode (ie, planar and DC), such as Figure 3a The 65 directional modes (planar mode and DC mode) are collectively referred to as 67 IPMs.

[0110] Depending on the prediction direction used by the luma block, the chroma block may also have limited access to intra prediction of these subdivided directional modes. However, intra prediction of chroma blocks may not always take advantage of the multiple directional modes available to luma blocks in addition to the horizontal and vertical directions. In order to be able to use these different directional modes, the prediction mode of the current chroma block needs to be set to DM (direct mode). By setting the prediction mode to DM, the current chroma block can take advantage of directional modes in addition to the horizontal and vertical modes of the luma block.

[0111] When a chroma block is encoded, the intra prediction modes most frequently used or defaulted to maintain video quality include planar mode, DC mode, vertical mode, horizontal mode, and DM. In DM, the intra prediction mode of the luma block spatially corresponding to the current chroma block is used as the intra prediction mode of the chroma block.

[0112] The video encoding device may signal the video decoding device whether the intra prediction mode of the chroma block is DM. The video encoding device may transmit DM to the video decoding device in a variety of ways. For example, the video encoding device may indicate whether the intra prediction mode of the chroma block is DM by setting intra_chroma_pred_mode, which is information for indicating the intra prediction mode of the chroma block, to a specific value and sending intra_chroma_pred_mode to the video decoding device.

[0113] When encoding a chroma block in an intra prediction mode, the video encoding apparatus may set the intra prediction mode IntraPredModeC of the chroma block according to Table 1.

[0114] Hereinafter, in order to distinguish intra_chroma_pred_mode from IntraPredModeC, which is information related to an intra prediction mode of a chroma block, the two are represented as a chroma intra prediction mode indicator and a chroma intra prediction mode, respectively.

[0115]

Table 1

[0116]

[0117] Here, lumaIntraPredMode is the intra prediction mode of the luma block corresponding to the current chroma block (hereinafter referred to as "luminance intra prediction mode"). lumaIntraPredMode indicates Figure 3a One of the prediction modes described in . For example, in Table 1, lumaIntraPredMode=0 refers to the planar prediction mode, and lumaIntraPredMode=1 refers to the DC prediction mode. The cases where lumaIntraPredMode is 18, 50, and 66 indicate directional modes called horizontal, vertical, and VDIA, respectively. On the other hand, the cases where intra_chroma_pred_mode=0, 1, 2, and 3 indicate the planar, vertical, horizontal, and DC prediction modes, respectively. The case where intra_chroma_pred_mode=4 is DM, in which the value of IntraPredModeC (chroma intra-frame prediction mode) is set equal to the value of lumaIntraPredMode.

[0118] Meanwhile, Table 2 shows a process of parsing an intra prediction mode of a chroma block performed by a video decoding apparatus.

[0119]

Table 2

[0120]

[0121] The video decoding device parses ccm_mode_flag, which indicates whether the cross-component linear model (CCLM) mode is used. If ccm_mode_flag is 1 to enable the CCLM mode, the video decoding device parses ccm_mode_idx indicating the CCLM mode. Depending on the value of ccm_mode_idx, the CCLM mode can indicate one of three modes. On the other hand, if ccm_mode_flag is 0, indicating that the CCLM mode is not used, the video decoding device parses intra_chroma_pred_mode indicating the intra-frame prediction mode, as described above.

[0122] If the CCLM mode is applied to the intra-frame prediction of the current chroma block, the video decoding device determines the corresponding area (hereinafter, "corresponding luminance area") corresponding to the current chroma block in the luminance image. For the prediction of the linear model, the left reference pixel and the upper reference pixel of the corresponding luminance area and the left reference pixel and the upper reference pixel of the target chroma block can be used. Hereinafter, the left reference pixel and the upper reference pixel are collectively referred to as reference pixels, neighboring pixels or neighboring pixels. In addition, the reference pixels in the chroma channel are referred to as chroma reference pixels, and the reference pixels in the luminance channel are referred to as luminance reference pixels.

[0123] In CCLM prediction, a prediction block as a predictor of a target chrominance block is generated by obtaining a linear model between reference pixels in a corresponding luminance region and reference pixels of a chrominance block, and then applying the linear model to reconstructed pixels in the corresponding luminance region. For example, four pairs of pixels (which are pixels in peripheral pixel rows of a current chrominance block and pixels in a combined corresponding luminance region) may be used to obtain the linear model. With respect to the four pairs of pixels, the video decoding device may obtain α and β representing the linear model, as shown in Equation 1.

[0124] [Equation 1]

[0125]

[0126] Here, X a and X b They represent the average of the minimum and second minimum values ​​of the corresponding brightness pixels in the four pairs of pixels, and the average of the maximum and second maximum values. a and Y b Each represents the average value of the minimum value and the second minimum value of the chrominance pixels in the four pairs of pixels, and the average value of the maximum value and the second maximum value. Then, the video decoding device can use a linear model to calculate the pixel value rec' of the corresponding brightness area. L (i, j) generates the predictor pred for the current chroma block C (i, j), as shown in Eq. 2.

[0127] [Equation 2]

[0128]

[0129] As described above, the CCLM mode is divided into three modes, CCLM_LT, CCLM_L, and CCLM_T, according to the positions of the neighboring pixels used in the derivation of the linear model. The CCLM_LT mode uses two pixels adjacent to the left and top of the current chroma block from the neighboring pixels in each direction. The CCLM_L mode uses four pixels adjacent to the left of the current chroma block from the neighboring pixels. Finally, the CCLM_T mode utilizes four pixels adjacent to the top of the current chroma block from the neighboring pixels.

[0130] The following embodiments are described with reference to a video decoding apparatus, but the following embodiments may be implemented identically or similarly in a video encoding apparatus.

[0131] II. Implementation methods according to the present disclosure

[0132] Figure 6 is a block diagram detailing a portion of a video decoding device according to at least one embodiment of the present disclosure.

[0133] According to some embodiments, the video decoding device can determine a prediction unit and a transform unit, and for a current block corresponding to the determined unit, perform prediction and inverse transform by using the determined prediction technology and prediction mode to finally generate a reconstructed block of the current block. Figure 6 The operations shown in FIG. 5 can be performed by the inverse transformer 530, the predictor 540, and the adder 550 of the video decoding device. Figure 6 The same operations shown in the figure can be performed by the inverse transformer 165, the picture divider 110, the predictor 120, and the adder 170 of the video encoding device. In this case, the video decoding device uses the encoding information parsed from the bit stream, but the video encoding device can use the encoding information set from a higher level in terms of minimizing the bit rate distortion. In the following, for convenience, the embodiment is described with the video decoding device as the center.

[0134] like Figure 5 As shown, the predictor 540 includes an intra-frame predictor 542 and an inter-frame predictor 544, depending on the prediction technique, but as shown in FIG. Figure 6 As shown, the predictor 540 may include all or part of a prediction unit determiner 602 , a prediction technique determiner 604 , a prediction mode determiner 606 , and a prediction executor 608 .

[0135] When the color format of the input video is a YUV format (YUV420, YUV411, YUV422, YUV444, etc.), the video decoding apparatus may perform prediction and reconstruction of the luminance component, and then may perform prediction and reconstruction of the chrominance component. In other words, the luminance component and the chrominance component may be obtained by Figure 6 On the other hand, when the color format of the input video is RGB, the video encoding device may perform a color format conversion from RGB to YUV, and then may encode the converted video. Here, in the case of the YUV format, the color format represents the correspondence between the pixels in the luminance component and the pixels in the chrominance component.

[0136] The prediction unit determiner 602 determines a prediction unit (PU). The prediction technique determiner 604 determines a prediction technique for the prediction unit, such as intra prediction, inter prediction, or intra block copy (IBC) mode, prediction of a palette mode, etc. The prediction mode determiner 606 determines a detailed prediction mode for the prediction technique. The prediction executor 608 generates a prediction block of the current block according to the determined prediction mode.

[0137] The inverse transformer 530 includes a transform unit determiner 610 and an inverse transform performer 612. The transform unit determiner 610 determines a transform unit (TU) with respect to an inverse quantization signal of a current block, and the inverse transform performer 612 inversely transforms the transform unit represented by the inverse quantization signal to generate a residual signal.

[0138] The adder 550 sums the predicted block and the residual signal to generate a reconstructed block. The reconstructed block is stored in a memory and can be used to predict other blocks in the future.

[0139] The prediction unit determined by the prediction unit determiner 602 may become a sub-block of the current block or a sub-block partitioned from the current block. In this case, the prediction unit of the chrominance component may correspond in size to the prediction unit of the luma component depending on the color format. Alternatively, the prediction units of the luma component and the chrominance component may be determined separately, and prediction may be performed for the prediction unit of the chrominance component.

[0140] The prediction technique determiner 604 determines the prediction technique for the prediction unit. As described above, the prediction technique may be one of inter prediction, intra prediction, IBC mode, and palette mode. In this case, the prediction technique of the chroma component may be determined to be the same as the prediction technique of the corresponding luma component without signaling and parsing separate information.

[0141] The following describes a case where, when the prediction mode determiner 606 determines the prediction mode of the current chroma block and the prediction performer 608 predicts the current chroma block, the prediction technique of the current chroma block is intra prediction.

[0142] In one embodiment, the prediction mode determiner 606 may determine an intra prediction mode (which uses adjacent reconstructed chroma samples of the current chroma block) as the prediction mode of the current chroma block. At this time, the prediction executor 608 may generate a prediction block of the current chroma block by using the adjacent reconstructed chroma samples according to the determined intra prediction mode.

[0143] In one embodiment, the prediction mode determiner 606 can determine, based on the signaling and parsing 1-bit flag, a mode that utilizes the relationship between adjacent reconstructed chroma samples of the current chroma component and adjacent reconstructed luminance samples of a luminance block at a corresponding position (hereinafter, "corresponding luminance block") as the prediction mode of the current chroma block.

[0144] At this time, the prediction executor 608 may model the relationship between the adjacent reconstructed chroma samples of the current chroma component and the adjacent reconstructed luma samples of the corresponding luma block. The prediction executor 608 may use the modeled relationship to generate a prediction block for the current chroma block.

[0145] In one embodiment, the prediction executor 608 may implicitly select a reconstructed luma sample region and a reconstructed chroma sample region for performing modeling based on statistical characteristics between the reconstructed luma sample region and the reconstructed chroma sample region. The prediction executor 608 may use the selected region to model the relationship between adjacent reconstructed chroma samples and adjacent reconstructed luma samples of the corresponding luma block.

[0146] As another embodiment, the video encoding device may signal an index indicating one of the regions, such as the upper side, the left side, or the upper left side of the current block. The prediction executor 608 may parse the index and select a region for modeling the prediction of the chrominance component based on the parsed index. The prediction executor 608 may use the selected region to model the relationship between adjacent reconstructed chrominance samples and adjacent reconstructed luma samples of the corresponding luma block.

[0147] Hereinafter, “modeling for prediction of chroma components” may be simply expressed as “modeling”.

[0148] As another embodiment, the prediction mode determiner 606 may determine a planar, DC, horizontal, vertical mode, or a direct mode (DM) as the prediction mode of the current chroma block.

[0149] For example, when performing prediction according to DM, the prediction performer 608 may generate a prediction block of the current chrominance block by using the same intra prediction mode as that of the corresponding luma block.

[0150] Figures 7a to 7c is a diagram illustrating the location of samples used for modeling according to at least one embodiment of the present disclosure.

[0151] In one embodiment, when the color format of the input video is YUV420 and the relationship between adjacent reconstructed chrominance samples and adjacent reconstructed luminance samples of the corresponding luminance block is modeled, the video decoding device may determine the left side of the current block, the top of the current block, or the top left of the current block as the position of the sample for modeling the prediction of the chrominance component, such as Figures 7a to 7c As shown in the example.

[0152] At this time, the video encoding apparatus may determine an index indicating a region of samples retained for modeling, and may send the determined index to the video decoding apparatus by a signal. The video decoding apparatus may parse the index, and determine a region of samples retained for modeling based on the parsed index.

[0153] As another embodiment, the video decoding device may implicitly determine the position of the area for modeling based on the prediction information in the corresponding luminance block. Here, the prediction information may include the aspect ratio of the block, the prediction mode of the block, etc.

[0154] In one embodiment, the video decoding device may be based on a video signal having a size W C ×H C The aspect ratio of the current chroma block implicitly determines the location of the region used for modeling. For example, if W C <H C , then Figure 7a The location of the area used for modeling is determined as shown in C >H C , then Figure 7b The location of the area to be modeled is determined as shown. Alternatively, if W C =H C , you can Figure 7c The position of the area for modeling is determined as shown in . Here, the aspect ratio represents the ratio of the width to the height of the block (width / height). Alternatively, the aspect ratio of the corresponding luminance block can be used to implicitly determine the position of the area for modeling.

[0155] exist Figures 7a to 7c In an embodiment of , "p" represents the width of the reconstructed area to the left of the corresponding luminance block, and "q" represents the width of the reconstructed area to the left of the current chrominance block. In addition, "r" represents the height of the reconstructed area at the top of the corresponding luminance block, and "s" represents the height of the reconstructed area at the top of the current chrominance block. In this case, the relationship between "p" and "q" and the relationship between "r" and "s" can be determined according to the color format of the input video. For example, if the color format of the input video is YUV420, q=p>>1, s=r>>1.

[0156] Further, the video decoding apparatus may determine the location of a region where samples for modeling are maintained according to a prediction mode of a corresponding luminance block, as follows.

[0157] Figure 8 is a resulting diagram showing the locations of samples used for modeling in accordance with at least one embodiment of the present disclosure.

[0158] First, a case where the block partition structures of the luminance component and the chrominance component are the same according to the use of a single tree structure is now described. In the case where the corresponding luminance block is not predicted based on the adjacent upper left reference row or region during the prediction process, and the corresponding luminance block is predicted based on a non-adjacent reference row or non-adjacent reference region that is separated by "a" (a natural number), as Figure 8 As shown in , the video decoding device can maintain samples used for modeling by setting a reconstruction area of ​​the luminance component from an area constructed from rows for prediction (hereinafter, the “reconstruction area of ​​the luminance component” omits the “maintain samples used for modeling” part), as Figure 8 In this case, the reconstruction region of the chroma component samples retained for modeling (hereinafter, “the reconstruction region of the chroma component”) may be a region adjacent to the current chroma block, such as Figure 8 As shown in Figure 8 In an embodiment of the present invention, the relationship between "p" and "q" and the relationship between "r" and "r" can be determined based on the color format of the input video.

[0159] Figure 9a and Figure 9b is a resulting diagram showing locations of samples used for modeling according to other embodiments of the present disclosure.

[0160] As another embodiment, depending on the distance between the corresponding luminance block and the reference line used for prediction of the corresponding luminance block, the video decoding apparatus may perform modeling by using the reconstructed non-adjacent area of ​​the chrominance component, such as Figure 9a In this case, the reference area for modeling can be determined based on the color format of the input video. Figure 9b As shown, if the distance between the reconstructed luminance area and the corresponding luminance block is "a", with respect to the luminance component, the reference area for modeling can be implicitly determined as the area at a distance "a" from the luminance block. In addition, with respect to the chrominance component, the reference area for modeling can be implicitly determined as the area at a distance "b" (which is a natural number) from the chrominance block.

[0161] At the same time, Figure 9a and Figure 9b In the embodiment of Figure 7cIn addition, "a" represents the distance between the corresponding luminance block and the reconstruction area, and "b" represents the distance between the current chrominance block and the reconstruction area. In this case, the relationship between "p" and "q", the relationship between "r" and "s", and the relationship between "a" and "b" can be determined according to the color format of the input video.

[0162] As another embodiment, Fig.10 As shown in , the following case is now described, in which the reference row used to predict the corresponding luminance block is not adjacent to the luminance block, the luminance block is predicted according to directional prediction, and the direction of the intra prediction mode is between the LH direction and the LV direction (that is, the lower left direction is preset). At this time, the reconstruction area of ​​the luminance component and the chrominance component can be implicitly determined to be only partially not adjacent to the current block, such as in Fig.10 in the example.

[0163] On the other hand, Fig.10 In the embodiment of Figure 7c In this case, the relationship between "p" and "q", the relationship between "r" and "s", and the relationship between "a" and "b" can be determined according to the color format of the input video.

[0164] As Fig.11 Another embodiment shown in , now describes the case where the reference row for predicting the corresponding luminance block is not adjacent to the luminance block, the luminance block is predicted according to directional prediction, and the direction of the intra prediction mode is between the RV direction and the RH direction (i.e., the preset upper right direction). In this case, the reconstruction area of ​​the luminance component and the chrominance component can be implicitly determined to be only partially not adjacent to the current block, such as in Fig.11 In the embodiment of .

[0165] On the other hand, Fig.11 In the embodiment of Figure 7c In this case, the relationship between "p" and "q", the relationship between "r" and "s", and the relationship between "a" and "b" can be determined according to the color format of the input video.

[0166] Next, the following case is now described, in which the use of the dual tree structure results in a difference between the block partition structure of the luma component and the block partition structure of the chroma component, so that a luma region at a corresponding position corresponding to the current chroma block (hereinafter, "corresponding luma region") is predicted as a plurality of blocks. At this time, the video decoding device may determine a reconstruction region to hold samples to be used for modeling according to a prediction mode of a block including an upper left boundary of the corresponding luma region.

[0167] Meanwhile, when the dual tree structure is used, the video decoding apparatus may represent a corresponding luminance block by a corresponding luminance region, and a luminance block within the corresponding luminance region may be represented by a sub-luminance block.

[0168] Fig.12a and 12b is an implicitly derived diagram illustrating the locations of samples used for modeling according to other embodiments of the present invention.

[0169] For example, the following case is now described, in which blocks adjacent to the upper boundary of a corresponding luminance region of size W×H (W is the width of the region and H is the height of the region) remain luminance blocks predicted by using non-adjacent reference lines, and in which those blocks have regions adjacent to the upper boundary of the corresponding luminance block and a predetermined width (e.g., “W>>1”) or more of the corresponding luminance block is assumed. In addition, the case also depends on that blocks adjacent to the left boundary of the corresponding luminance region remain luminance blocks predicted by using non-adjacent reference lines, and those luminance blocks have regions adjacent to the left boundary of the corresponding luminance block and a predetermined height (e.g., “H>>1”) or more of the corresponding luminance block is assumed. As Fig.12a As shown, the reconstruction area of ​​the luma component can be implicitly determined as an area that is "a" and "b" (where "a" and "b" are 0 or natural numbers) away from the corresponding luma area. In addition, the reconstruction area of ​​the chroma component can be implicitly determined as an area that is "c" and "d" away from the chroma block. Here, "a" can be the distance to the row closest to the corresponding luma block among the non-adjacent reference rows used in the prediction process of the block adjacent to the top of the corresponding luma area, and "b" can be the distance to the row closest to the luma block among the non-adjacent reference rows used in the prediction process of the block adjacent to the left side of the corresponding luma area.

[0170] Further, when "a" or "b" is zero, the top or left region of the sample kept for modeling can be the region constructed by adjacent reference rows, rather than the region constructed by non-adjacent reference rows, as in Figure 12b In the example of Figure 12b In the embodiment of , "a" is 0. Figure 12b In the embodiment of , the luminance block 2 predicted by using the non-adjacent reference lines can use the non-adjacent reference lines because the area "k" adjacent to the left boundary of the corresponding luminance area is "H>>1" or larger.

[0171] At the same time, Fig.12a and Figure 12b In the embodiment of Figure 7cIn addition, "a" represents the shortest distance between the corresponding luminance area and the top reconstruction area, and "c" represents the distance between the current chrominance block and the top reconstruction area. "b" represents the shortest distance between the corresponding luminance area and the left reconstruction area, and "d" represents the distance between the current chrominance block and the left reconstruction area. At this time, the relationship between "p" and "q", the relationship between "r" and "s", the relationship between "a" and "c", and the relationship between "b" and "d" can be determined according to the color format of the input video.

[0172] Fig.13a and 13b is an implicitly derived graph illustrating the locations of samples used for modeling according to other embodiments of the present disclosure.

[0173] As another embodiment, a case is now described in which a block adjacent to the upper left boundary of the corresponding luma region of size W×H holds both a luma block predicted by using a non-adjacent reference line and a luma block predicted by using an adjacent reference line. The reconstructed region of the luma component may be implicitly determined as a non-adjacent region with respect to a region in which the block predicted by using a non-adjacent reference line is held, and implicitly determined as a neighboring region with respect to a region in which the block predicted by using an adjacent reference line is held, as Fig.13a and 13b In addition, regarding the area determined in the luminance component, the reconstruction area in the chrominance component can be determined to be at a corresponding position according to the color format.

[0174] exist Fig.13a In the embodiment of , there is no luminance block predicted by using adjacent reference lines. Therefore, for a region having a block predicted by using non-adjacent reference lines, the reconstructed region of the luminance component is determined as a non-adjacent region. On the other hand, if a, b, c, and / or d are zero, there may be a luminance block predicted by using adjacent reference lines. In this case, Fig.13b As shown, the top or left region of the samples kept for modeling may include the neighboring region of the block predicted by using the neighboring reference lines. Fig.13b In the embodiment, "b" and "c" are zero.

[0175] At the same time, Fig.13a and 13b In the embodiment of , a, b, c and d represent the distances between the corresponding luminance region and the reconstruction region, and e, f, g and h corresponding to a, b, c and d, respectively, represent the distances between the current chrominance block and the reconstruction region. At this time, the relationship between "a" and "e", the relationship between "b" and "f", the relationship between "c" and "g", and the relationship between "d" and "h" can be determined according to the color format of the input video.

[0176] On the other hand, if a reconstruction area of ​​the luminance component and a reconstruction area of ​​the chrominance component that maintains samples to be used for modeling are determined, the video decoding device can use samples in the determined reconstruction area of ​​each component to obtain parameters α and β representing the linear relationship between the components.

[0177] In one embodiment, the video decoding device may obtain the parameter using all samples in the region of each component. For example, after sorting the samples in the reconstruction region of the luminance component in descending order and sorting the samples in the reconstruction region of the chrominance component in descending order, the video decoding device may calculate L as the average of the maximum value and the second maximum value and the average of the minimum value and the second minimum value for each component. m-max , L m-min , C m-max and C m-max The video decoding device may then obtain α and β as shown in Equation 3.

[0178] [Equation 3]

[0179]

[0180] As another embodiment, the video decoding device may obtain the parameter by using only those samples corresponding to the predetermined position based on the block size in the region of each component. For example, after sorting the samples at the predetermined position in the reconstruction region of the luminance component in descending order and sorting the samples at the predetermined position in the reconstruction region of the chrominance component in descending order, the video decoding device may calculate L as the average value of the maximum value and the second maximum value and the average value of the minimum value and the second minimum value for each component. m-max , L m-min , C m-max and C m-min The video decoding device may then obtain α and β as shown in Equation 3.

[0181] The video decoding device may then use the calculated parameters to calculate the prediction sample Pred of the chrominance component. chroma , as shown in Equation 4.

[0182] [Equation 4]

[0183]

[0184] Here, Rec' Luma It can be the sample value in the corresponding luma block or the sample value in the corresponding luma block of the next sample.

[0185] As described above, the video decoding apparatus may obtain α and β, and then may generate a prediction block of the current chrominance block according to Equation 4. In addition, the video decoding apparatus may correct the obtained α and β, respectively, and apply the corrected α and β to Equation 4 to generate a prediction block of the current chrominance block.

[0186] As another embodiment, the video decoding apparatus may separate the equation into a plurality of linear equations instead of using a single equation, may obtain α and β for each of the linear equations, and may use the obtained parameters to generate a prediction block of the current chroma block.

[0187] In the following, a case where the prediction mode of the current chroma block is determined as a plane, DC, horizontal, vertical mode, DM, or a mode using a neighboring reference area of ​​the current chroma block is described. The video decoding apparatus may implicitly set the position of the reference row used for prediction of the current chroma block based on the prediction mode of the corresponding luminance block.

[0188] Fig.14 is a resulting diagram showing reconstructed reference lines or regions of chroma components according to at least one embodiment of the present disclosure.

[0189] First, a case where the luminance component and the chrominance component have the same block partition structure according to the use of a single tree structure is described. During the prediction process, as in Fig.14 In the case of predicting the corresponding luminance block as in the embodiment of , not based on the adjacent upper left reference line or area, but based on the non-adjacent reference line or non-adjacent reference area, the video decoding device can use the non-adjacent reference line or area of ​​the current chrominance block to set the reconstruction reference line or area of ​​the chrominance component, as in Fig.14 As in the example of . Fig.14 In the embodiment of , "a" (natural number) represents the distance between the corresponding luminance block and the reconstruction area, and "b" represents the distance between the current chrominance block and the reconstruction area. In this case, the relationship between "a" and "b" can be determined based on the color format of the input video.

[0190] Next, a case is described in which, according to the use of a dual tree structure, the luminance component and the chrominance component have different block partition structures, so that the luminance region corresponding to the current chrominance block is predicted as a plurality of blocks. At this time, the video decoding device may determine the reconstruction reference row or region of the chrominance component according to the prediction mode of the block including the upper left boundary of the corresponding luminance region, as follows.

[0191] On the other hand, when the dual tree structure is used, the corresponding luminance block may be represented by the corresponding luminance region, and the luminance block within the corresponding luminance region may be represented by a sub-luminance block.

[0192] Fig.15a and 15bis an implicitly derived diagram illustrating reconstructed reference lines or regions of chroma components in accordance with at least one embodiment of the present invention.

[0193] In an example case, a block adjacent to an upper boundary of a corresponding luminance area of ​​size W×H remains a luminance block predicted by using a non-adjacent reference line, and the luminance block has an area adjacent to the upper boundary of the luminance block and assumes a predetermined ratio (e.g., “W>>1”) or more of the width of the corresponding luminance block. This case also depends on that a block adjacent to a left boundary of the luminance block remains a luminance block predicted by using a non-adjacent reference line, and the luminance block has an area adjacent to the left boundary of the luminance block and assumes a predetermined ratio (e.g., “H>>1”) or more of the height of the corresponding luminance block. As Fig.15a As shown, the reconstruction reference line or area of ​​the chroma component can be implicitly determined as a line or area at a distance "c" and "d" from the chroma block. Here, "c" can be determined based on a distance "a" (0 ​​or a natural number) to a line closest to the corresponding luminance area among non-adjacent reference lines used in a prediction process of a block adjacent to an upper boundary of the corresponding luminance area, and "d" can be determined based on a distance "b" (0 or a natural number) to a line closest to the corresponding luminance area among non-adjacent reference lines used in a prediction process of a block adjacent to a left boundary of the corresponding luminance area.

[0194] In addition, as in Fig.15b In the embodiment of , when "a" or "b" is 0, the reconstruction reference line or area of ​​the chrominance component can be an area constructed by adjacent reference lines or areas, rather than an area constructed by non-adjacent reference lines or areas. Fig.15b In the embodiment of , "a" is 0. Fig.15b In the embodiment of FIG. 5 , the luminance block 2 predicted by using the non-adjacent reference lines may use the non-adjacent reference lines because the area k adjacent to the left boundary of the corresponding luminance area is 'H>>1' or greater.

[0195] exist Fig.15a and Fig.15b In the embodiment of , "a" represents the shortest distance between the corresponding luma region and the top reconstruction region, and "c" represents the distance between the current chroma block and the top reconstruction region. "b" represents the shortest distance between the corresponding luma region and the left reconstruction region, and "d" represents the distance between the current chroma block and the left reconstruction region. In this case, the relationship between "a" and "c" and the relationship between "b" and "d" can be determined according to the color format of the input video.

[0196] Fig.16 is a diagram showing an implicit derivation of a reconstructed reference line or region of a chroma component according to another embodiment of the present disclosure.

[0197] As another embodiment, a case is described where there are luma blocks predicted by using non-adjacent reference lines and luma blocks predicted by using adjacent reference lines for luma blocks adjacent to the upper left boundary of a corresponding luma region having a size of W×H. Among the corresponding luma regions, the video decoding apparatus may correspond the non-adjacent region to the chroma blocks of the region for holding the blocks predicted by using the non-adjacent reference lines, and correspond the adjacent region to the chroma blocks of the region for holding the blocks predicted by using the adjacent reference lines. Therefore, as Fig.16 As shown in , the reconstruction reference lines or regions of the chroma components can be implicitly determined.

[0198] exist Fig.16 In an embodiment of the present invention, there is no luminance block predicted by using an adjacent reference row. Therefore, the reconstructed reference row or region of the chrominance component is determined to correspond to a non-adjacent region, where the region holds the block predicted by using the non-adjacent reference row. On the other hand, if a, b, c, and / or d is 0, there is a luminance block predicted by using an adjacent reference row. In this case, the reconstructed reference row or region of the chrominance component can be determined to correspond to an adjacent region with respect to the block predicted by using the adjacent reference row.

[0199] At the same time, Fig.16 In the embodiment of , a, b, c, and d represent the distance between the corresponding luminance region and the reconstruction region, and e, f, g, and h correspond to a, b, c, and d, respectively, and represent the distance between the current chrominance block and the reconstruction region. The relationship between "a" and "e", the relationship between "b" and "f", the relationship between "c" and "g", and the relationship between "d" and "h" can be determined according to the color format of the input video.

[0200] See now Fig.17 and 18 , describes a method for encoding and decoding chrominance blocks.

[0201] Fig.17 The present invention is a flowchart of a method for performing intra-frame prediction on a current block, performed by a video encoding apparatus according to at least one embodiment of the present invention.

[0202] The video encoding device obtains a corresponding luminance block of the current chrominance block based on a color format (S1700). Here, the color format indicates a correspondence between pixels in the corresponding luminance block and pixels in the current chrominance block. In addition, it is assumed that the luminance component is decoded before decoding the current chrominance block according to a decoding order on the decoder side in the video encoding device.

[0203] Based on the block partition structure of the luminance component and the chrominance component, and the prediction information of the corresponding luminance block, the video encoding device obtains a reconstruction area for the luminance component of the corresponding luminance block, and obtains a reconstruction area for the chrominance component of the current chrominance block (S1702). Here, the prediction information may include an aspect ratio of the block, a prediction mode of the block, etc.

[0204] The video encoding apparatus models a relationship between samples in a reconstruction region of a luma component and samples in a reconstruction region of a chroma component ( S1704 ).

[0205] The video encoding apparatus generates a first prediction block of the current chrominance block from samples in the corresponding luminance block by using a modeling relationship ( S1706 ).

[0206] The video encoding apparatus obtains a reconstruction reference row or reference area of ​​the current chrominance block based on the block partition structure and prediction information of the corresponding luminance block ( S1708 ).

[0207] The video encoding apparatus generates a second prediction block of a current chroma block by using a reconstructed reference line or reference area ( S1710 ).

[0208] Based on the first prediction block and the second prediction block, the video encoding apparatus determines a prediction mode indicating whether to use the modeled relationship ( S1712 ).

[0209] In terms of rate-distortion optimization, the video encoding device may determine a prediction mode for intra-frame prediction of the current block. For example, if the first prediction block is optimal, the video encoding device may select a prediction mode that utilizes a modeled relationship. On the other hand, if the second prediction block is optimal, the video encoding device selects a prediction mode that does not use a modeled relationship. The prediction mode that does not use a modeled relationship may include a plane, DC, horizontal, vertical mode, DM, or a mode that performs prediction by using an adjacent reference area of ​​the current chrominance block.

[0210] The video encoding apparatus encodes the prediction mode (S1714).

[0211] Fig.18 The present invention is a flowchart of a method for performing intra-frame prediction on a current block, performed by a video decoding device according to at least one embodiment of the present invention.

[0212] The video decoding device obtains a corresponding luminance block of the current chrominance block based on a color format (S1800). Here, the color format indicates a correspondence between pixels of the corresponding luminance block and pixels of the current chrominance block. In addition, it is assumed that the luminance component is decoded before decoding the current chrominance block according to a decoding order.

[0213] The video decoding apparatus decodes a prediction mode of a current chroma block from a bitstream ( S1802 ).

[0214] The video decoding apparatus determines whether the prediction mode uses a modeling relationship (S1804). Here, the modeling relationship represents a relationship between samples in a reconstruction region of a luminance component and samples in a reconstruction region of a chrominance component.

[0215] If the prediction mode utilizes the modeling relationship (Yes in S1804 ), the video decoding apparatus performs the following steps ( S1806 to S1810 ).

[0216] Based on the block partition structure of the luminance component and the chrominance component and the prediction information of the corresponding luminance block, the video decoding device obtains the reconstruction area of ​​the luminance component of the corresponding luminance block and the reconstruction area of ​​the chrominance component of the current chrominance block (S1806). Here, the prediction information may include the aspect ratio of the block, the prediction mode of the block, etc.

[0217] The video decoding apparatus models a relationship between samples in a reconstruction region of a luma component and samples in a reconstruction region of a chroma component ( S1808 ).

[0218] The video decoding apparatus generates a prediction block of a current chrominance block from samples in a corresponding luminance block using a modeling relationship ( S1810 ).

[0219] On the other hand, if the prediction mode does not use the modeling relationship (No in S1804), the video decoding device performs the following steps (S1820 to S1822). Here, the prediction mode that does not use the modeling relationship may include a plane, DC, horizontal, vertical mode, direct mode (DM), or a mode that performs prediction by using an adjacent reference area of ​​the current chroma block.

[0220] The video decoding apparatus obtains a reconstruction reference line or a reference area of ​​a current chrominance block based on prediction information and a block partition structure of a corresponding luminance block ( S1820 ).

[0221] The video decoding apparatus generates a prediction block of the current chroma block by using a reconstructed reference line or a reference area according to a prediction mode ( S1822 ).

[0222] Although the steps in each flowchart are described as being performed sequentially, these steps are merely illustrative of the technical concepts of some embodiments of the present disclosure. Therefore, a person of ordinary skill in the art to which the present disclosure belongs can perform the steps by changing the order described in each figure or by performing two or more steps in parallel. Therefore, the steps in each flowchart are not limited to the time series order shown.

[0223] It should be understood that the above description presents illustrative embodiments that can be implemented in different other ways. The functions described in some embodiments can be implemented by hardware, software, firmware and / or a combination thereof. It should also be understood that the functional components described in this disclosure are marked with "... units" to strongly emphasize the possibility of their independent implementation.

[0224] Meanwhile, various methods or functions described in some embodiments may be implemented as instructions stored in a non-transitory recording medium that can be read and executed by one or more processors. For example, the non-transitory recording medium may include various types of recording devices in which data is stored in a form readable by a computer system. For example, the non-transitory recording medium may include a storage medium such as an erasable programmable read-only memory (EPROM), a flash drive, an optical drive, a magnetic hard drive, and a solid-state drive (SSD).

[0225] Although the embodiments of the present disclosure have been described for illustrative purposes, however, those of ordinary skill in the art to which the present disclosure belongs should recognize that various modifications, additions, and substitutions are possible without departing from the concept and scope of the present disclosure. Therefore, for the sake of brevity and clarity, the embodiments of the present disclosure have been described. The scope of the technical concept of the embodiments of the present disclosure is not limited by the diagrams. Therefore, those of ordinary skill in the art to which the present disclosure belongs should understand that the scope of the present disclosure should not be limited by the embodiments explicitly described above, but by the claims and their equivalents.

[0226] (reference number)

[0227] 122: Intra-frame predictor

[0228] 542: Intra-frame predictor

[0229] 602: Prediction unit determiner

[0230] 604: Prediction Technology Determiner

[0231] 606: Prediction Mode Determiner

[0232] 608: Predictive Executor.

[0233] CROSS-REFERENCE TO RELATED APPLICATIONS

[0234] This application claims priority to and the benefit of Korean Patent Application No. 10-2022-0099336, filed on August 9, 2022, and Korean Patent Application No. 10-2023-0082623, filed on June 27, 2023, the entire contents of each of which are incorporated herein by reference.

Claims

1. A method for performing intra-frame prediction on a current chrominance block performed by a video decoding device, the method comprising: Based on a color format, obtaining a corresponding luminance block corresponding to the current chrominance block, wherein the color format represents a correspondence between pixels of the corresponding luminance block and pixels of the current chrominance block; Based on the block partition structure for the luminance component of the corresponding luminance block and the chrominance component of the current chrominance block and the prediction information of the corresponding luminance block, obtain a reconstruction area of ​​the luminance component and obtain a reconstruction area of ​​the chrominance component; modeling a relationship between samples in the reconstructed region of the luma component and samples in the reconstructed region of the chroma components; and A prediction block for the current chrominance block is generated from samples in the corresponding luma block using the modeled relationship.

2. The method according to claim 1, further comprising: decoding a prediction mode of the current chroma block from a bitstream; as well as determining whether the prediction mode utilizes the modeled relationship, When the prediction mode utilizes the modeled relationship, the reconstructed region is obtained by continuing to generate the prediction block.

3. The method of claim 2, further comprising, when the prediction mode does not utilize the modeled relationship: Obtaining a reconstructed reference row or reference area of ​​the current chrominance block based on the block partition structure and the prediction information of the corresponding luminance block; and According to the prediction mode, a prediction block of the current chroma block is generated by using the reconstructed reference line or reference area.

4. The method according to claim 1, wherein: The reconstructed areas include: The reconstruction region of the luma component is determined by a left reconstruction region of the corresponding luma block, an upper reconstruction region of the corresponding luma block, or an upper-left reconstruction region of the corresponding luma block based on an aspect ratio of the corresponding luma block.

5. The method according to claim 4, wherein: The reconstructed areas include: According to the color format, the reconstruction region of the chrominance component is determined as a region corresponding to the reconstruction region of the luminance component.

6. The method according to claim 1, wherein: The reconstructed areas include: When the block partition structure is a single tree structure, and when the corresponding luminance block is predicted based on a non-adjacent reference row or a non-adjacent reference region, the reconstructed region of the luminance component is constructed from the non-adjacent reference row or the non-adjacent reference region, wherein the non-adjacent reference row or the non-adjacent reference region is separated from the corresponding luminance block by a natural number "a".

7. The method according to claim 6, wherein: The reconstructed areas include: The reconstructed region of the chrominance component is constructed as a region adjacent to the current chrominance block.

8. The method according to claim 1, wherein: The reconstructed areas include: When the block partition structure is a single tree structure, a reconstructed non-neighboring area based on a distance between the corresponding luminance block and a reference line used to predict the corresponding luminance block is used.

9. The method according to claim 8, wherein: The reconstructed areas include: When the corresponding luminance block is predicted based on a non-adjacent reference row that is a natural number "a" away from the corresponding luminance block, the reconstructed area of ​​the luminance component is constructed as an area that is a natural number "a" away from the corresponding luminance block, and the reconstructed area of ​​the chrominance component is constructed as an area that is a natural number "b" away from the current chrominance block, wherein "a" and "b" have a relationship determined according to the color format.

10. The method according to claim 1, wherein: The reconstructed areas include: When the block partition structure is a single tree structure, the reference row used for predicting the corresponding luminance block is not adjacent to the corresponding luminance block, the corresponding luminance block is predicted according to directional prediction, and the prediction mode of the directional prediction is a preset direction, a portion of the reconstruction area of ​​the luminance component and the chrominance component is determined by an area that is not adjacent to the corresponding luminance area and the current chrominance block.

11. The method according to claim 1, wherein: The reconstructed areas include: In the case where the block partition structure is a dual-tree structure, a reconstruction area of ​​the luminance component is determined by an area that is distanced "a" and "b" from the corresponding luminance block, a block adjacent to an upper boundary of the corresponding luminance block remains a sub-luminance block predicted by using a non-adjacent reference line, the sub-luminance block having an area adjacent to the upper boundary of the corresponding luminance block and assuming a predetermined ratio or more of a width of the corresponding luminance block, a block adjacent to a left boundary of the corresponding luminance block remains a sub-luminance block predicted by using a non-adjacent reference line, the sub-luminance block having an area adjacent to a left boundary of the corresponding luminance block and assuming a predetermined ratio or more of a height of the corresponding luminance block, Wherein, the "a" is the distance of the reference row closest to the corresponding luminance block among the non-adjacent reference rows of the block adjacent to the upper boundary, and the "b" is the distance of the reference row closest to the corresponding luminance block among the non-adjacent reference rows of the block adjacent to the left boundary.

12. The method according to claim 11, wherein: The reconstructed areas include: The reconstructed area of ​​the chrominance component is constructed as an area that is "c" and "d" away from the current chrominance block, wherein the "a" and the "c" have a relationship determined according to the color format, and the "b" and the "d" have a relationship determined according to the color format.

13. The method according to claim 1, wherein: The reconstructed areas include: When the block partition structure is a dual-tree structure, and when a block adjacent to the upper left boundary of the corresponding luminance block maintains both a sub-luminance block predicted by using a non-adjacent reference line and a sub-luminance block predicted by using an adjacent reference line, for an area having a sub-luminance block predicted by using the non-adjacent reference line, the reconstructed area of ​​the luminance component is determined as a non-adjacent area, and for an area having a sub-luminance block predicted by using the adjacent reference line, the reconstructed area of ​​the luminance component is determined as an adjacent area.

14. A method for performing intra-frame prediction on a current chrominance block, performed by a video encoding device, the method comprising: Based on a color format, obtaining a corresponding luminance block corresponding to the current chrominance block, wherein the color format represents a correspondence between pixels of the corresponding luminance block and pixels of the current chrominance block; Based on the block partition structure for the luminance component of the corresponding luminance block and the chrominance component of the current chrominance block and the prediction information of the corresponding luminance block, obtain a reconstruction area of ​​the luminance component and obtain a reconstruction area of ​​the chrominance component; modeling a relationship between samples in the reconstructed region of the luma component and samples in the reconstructed region of the chroma components; and A first prediction block for the current chrominance block is generated from samples in the corresponding luma block using the modeled relationship.

15. The method according to claim 14, further comprising: Obtaining a reconstructed reference row or reference region of the current chrominance block based on the block partition structure and prediction information of the corresponding luminance block; as well as A second prediction block of the current chroma block is generated by using the reconstructed reference line or reference area.

16. The method according to claim 15, further comprising: determining a prediction mode indicating whether to use the modeled relationship based on the first prediction block and the second prediction block; as well as The prediction mode is encoded.

17. A computer-readable recording medium storing a bit stream generated by a video encoding method, the video encoding method comprising: Based on a color format, obtaining a corresponding luminance block corresponding to the current chrominance block, wherein the color format represents a correspondence between pixels of the corresponding luminance block and pixels of the current chrominance block; Based on the block partition structure for the luminance component of the corresponding luminance block and the chrominance component of the current chrominance block and the prediction information of the corresponding luminance block, obtain a reconstruction area of ​​the luminance component and obtain a reconstruction area of ​​the chrominance component; modeling a relationship between samples in the reconstructed region of the luma component and samples in the reconstructed region of the chroma components; and A prediction block for the current chrominance block is generated from samples in the corresponding luma block using the modeled relationship.

Images