CN117044212A

CN117044212A - Video coding and decoding method and device using deblocking filtering based on segmentation information

Info

Publication number: CN117044212A
Application number: CN202280019878.2A
Authority: CN
Inventors: 崔韩率; 李民勋; 沈东圭; 朴胜煜
Original assignee: Hyundai Motor Co; Industry Academic Collaboration Foundation of Kwangwoon University; Kia Corp
Current assignee: Hyundai Motor Co; Industry Academic Collaboration Foundation of Kwangwoon University; Kia Corp
Priority date: 2021-03-09
Filing date: 2022-03-04
Publication date: 2023-11-10
Also published as: KR20220126641A

Abstract

Disclosed are a video encoding and decoding method and apparatus using deblocking filtering based on partition information, and the present embodiment provides a video encoding and decoding method and apparatus that prevent filtering from being performed at the boundary of an object within a picture by performing deblocking filtering using partition information of the picture.

Description

Video coding and decoding method and device using deblocking filtering based on segmentation information

Technical Field

The present invention relates to a video encoding and decoding method and apparatus using deblocking filtering based on partition information.

Background

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

Since video data has a larger data amount than audio data or still image data, the video data requires a large amount of hardware resources (including a memory) to store or transmit the video data that is not subjected to compression processing.

Accordingly, encoders are typically used to compress and store or transmit video data. The decoder receives the compressed video data, decompresses the received compressed video data, and plays the decompressed video data. Video compression techniques include h.264/AVC, high efficiency video codec (High Efficiency Video Coding, HEVC), and multi-function video codec (Versatile Video Coding, VVC) that has an increase in codec efficiency of HEVC of about 30% or more.

On the other hand, in VVC technology, a video encoding/decoding device performs in-loop filtering in the order of luminance mapping (Luma Mapping with Chroma Scaling, LMCS) with chroma scaling, deblocking filtering, sample adaptive offset (Sample Adaptive Offset, SAO) filters, and adaptive loop filters (Adaptive Loop Filter, ALF). Deblocking filtering performs long filtering or short filtering, and short length filtering includes strong filtering and weak filtering, as in the HEVC standard. The video encoding/decoding device performs deblocking filtering in order of determining boundaries and filter lengths, determining whether to apply filtering, determining a type of filtering, and performing filtering.

Deblocking filtering is performed on four columns around a horizontal deblocking boundary or four rows around a vertical deblocking boundary. The video encoding/decoding device determines the presence or absence of deblocking filtering, a filter length, and a filter strength based on every four columns or every four rows. The determination process may utilize pixels from the first and last columns of four columns or the first and last rows of four rows.

On the other hand, as the image size, resolution, and frame rate gradually increase, the amount of data to be encoded also increases. Accordingly, there is also a need for a new compression technique that provides higher coding efficiency and improved image enhancement compared to existing compression techniques in terms of deblocking filtering.

Disclosure of Invention

Technical problem

In some implementations, the present disclosure seeks a video codec method and device that utilizes segmentation information of an image to perform deblocking filtering to avoid performing filtering at boundaries of objects within the image.

Technical proposal

At least one aspect of the present disclosure provides a method performed by a computing device for applying deblocking filtering to a restored region of an image. The method includes performing segmentation on the restored region to partition the restored region into separate objects, and generating segmentation information of the objects. The restored region is an image, a slice, or a plurality of coding units. The method further includes selecting a boundary between the coding unit and the transform unit within the restored region as a filtering boundary to which deblocking filtering is applied. The method further includes initializing, for each filter boundary, a P filter length and a Q filter length for each block adjacent to the filter boundary. The method further includes setting a P sub-region and a Q sub-region belonging to the same object using partition information of the P region and the Q region having a predetermined size adjacent to the filtering boundary, and adjusting the P filter length and the Q filter length. The method further includes calculating a degree of spatial variation of the P sub-region and the Q sub-region based on the adjusted P filter length and the Q filter length. The method further includes determining whether to apply deblocking filtering based on the degree of spatial variation of the P sub-region and the Q sub-region, and determining a type of deblocking filter when the deblocking filtering is applied. The method further includes performing deblocking filtering by applying a deblocking filter to the P sub-region and the Q sub-region.

Another aspect of the present invention provides a deblocking filter apparatus. The apparatus includes a segmentation execution unit configured to perform segmentation on the restored region to partition the restored region into separate objects, and generate segmentation information of the objects. The restored region is an image, a slice, or a plurality of coding units. The apparatus further includes a boundary and filter length determination unit configured to select a boundary between the coding unit and the transform unit within the restored region as a filtering boundary to which deblocking filtering is applied, and initialize a P filter length and a Q filter length of each block adjacent to the filtering boundary for each filtering boundary. The apparatus further includes a filter length adjustment unit configured to set a P sub-region and a Q sub-region belonging to the same object using partition information of the P region and the Q region having predetermined sizes adjacent to the filtering boundary, and adjust the P filter length and the Q filter length. The apparatus further includes a deblocking determination unit configured to calculate a degree of spatial variation of the P sub-region and the Q sub-region based on the adjusted P filter length and Q filter length, determine whether to apply deblocking filtering based on the degree of spatial variation of the P sub-region and the Q sub-region, and determine a type of the deblocking filter when the deblocking filtering is applied. The apparatus further includes a deblocking performing unit configured to perform deblocking filtering by applying a deblocking filter to the P sub-region and the Q sub-region.

Advantageous effects

As described above, the present invention provides a video encoding and decoding method and apparatus that performs deblocking filtering using partition information of an image to avoid filtering at a boundary of an object within the image. Therefore, the image quality can be improved.

Drawings

Fig. 1 is a block diagram of a video encoding device in which the techniques of the present invention may be implemented.

Fig. 2 illustrates a method of partitioning a block using a quadtree plus binary tree trigeminal tree (QTBTTT) structure.

Fig. 3a and 3b illustrate a plurality of intra prediction modes including a wide-angle intra prediction mode.

Fig. 4 shows neighboring blocks of the current block.

Fig. 5 is a block diagram of a video decoding apparatus in which the techniques of the present invention may be implemented.

Fig. 6 is a block diagram showing an deblocking filtering apparatus.

Fig. 7 shows P blocks and Q blocks adjacent to a vertical boundary as a filtering boundary.

Fig. 8 shows the boundary portion and the P region and the Q region on both sides of the boundary portion.

Fig. 9 is a block diagram illustrating a deblocking filtering apparatus using segmentation information according to one embodiment of the present invention.

Fig. 10 shows P and Q regions of size m×n.

Fig. 11a to 11c show sub-regions using segmentation results according to one embodiment of the present invention.

Fig. 12 is a flowchart illustrating a deblocking filtering method according to an embodiment of the present invention.

Detailed Description

Hereinafter, some embodiments of the present invention will be described in detail with reference to the accompanying illustrative drawings. In the following description, like reference numerals denote like elements, although the elements are shown in different drawings. Furthermore, in the following description of some embodiments, detailed descriptions of related known components and functions have been omitted for clarity and conciseness when it may be considered that the subject matter of the present invention is obscured.

Fig. 1 is a block diagram of a video encoding device in which the techniques of the present invention may be implemented. Hereinafter, a video encoding apparatus and components of the apparatus are described with reference to the diagram of fig. 1.

The encoding apparatus may include: an image divider 110, a predictor 120, a subtractor 130, a transformer 140, a quantizer 145, a reordering unit 150, an entropy encoder 155, an inverse quantizer 160, an inverse transformer 165, an adder 170, a loop filtering unit 180, and a memory 190.

Each component of the encoding apparatus may be implemented as hardware or software, or as a combination of hardware and software. In addition, the function of each component may be implemented as software, and the microprocessor may also be implemented to execute the function of the software corresponding to each component.

A video is made up of one or more sequences comprising a plurality of images. Each image is divided into a plurality of regions, and encoding is performed on each region. For example, an image is segmented into one or more tiles (tiles) or/and slices (slices). Here, one or more tiles may be defined as a tile set. Each tile or/and slice is partitioned into one or more Coding Tree Units (CTUs). In addition, each CTU is partitioned into one or more Coding Units (CUs) by a tree structure. Information applied to each CU is encoded as a syntax of the CU, and information commonly applied to CUs included in one CTU is encoded as a syntax of the CTU. In addition, information commonly applied to all blocks in one slice is encoded as syntax of a slice header, and information applied to all blocks constituting one or more pictures is encoded as a picture parameter set (Picture Parameter Set, PPS) or a picture header. Furthermore, information commonly referred to by the plurality of images is encoded as a sequence parameter set (Sequence Parameter Set, SPS). In addition, information commonly referenced by the one or more SPS is encoded as a set of video parameters (Video Parameter Set, VPS). Furthermore, information commonly applied to one tile or group of tiles may also be encoded as syntax of the tile or group of tiles header. The syntax included in the SPS, PPS, slice header, tile, or tile set header may be referred to as a high level syntax.

The image divider 110 determines the size of a Coding Tree Unit (CTU). Information about the size of the CTU (CTU size) is encoded as a syntax of the SPS or PPS and transmitted to the video decoding apparatus.

The image divider 110 divides each image 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. Leaf nodes in the tree structure become Coding Units (CUs), which are the basic units of coding.

The tree structure may be a Quadtree (QT) in which a higher node (or parent node) is partitioned 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 split into two lower nodes. The tree structure may also be a Trigeminal Tree (TT), where the higher nodes are split 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 a QT structure, a BT structure, and a TT structure are mixed. For example, a quadtree plus binary tree (quadtree plus binarytree, QTBT) structure may be used, or a quadtree plus binary tree (quadtree plus binarytree ternarytree, QTBTTT) structure may be used. Here, BTTT is added to the tree structure to be called multiple-type tree (MTT).

Fig. 2 is a schematic diagram for describing a method of dividing a block by using the QTBTTT structure.

As shown in fig. 2, the CTU may be first partitioned into QT structures. Quadtree partitioning may be recursive until the size of the partitioned block reaches the minimum block size (MinQTSize) of leaf nodes allowed in QT. A first flag (qt_split_flag) indicating whether each node of the QT structure is partitioned into four lower-layer nodes is encoded by the entropy encoder 155 and signaled to the video decoding apparatus. When the leaf node of QT is not greater than the maximum block size (MaxBTSize) of the root node allowed in BT, the leaf node may be further divided into at least one of BT structure or TT structure. There may be multiple directions of segmentation in the BT structure and/or the TT structure. For example, there may be two directions, i.e., a direction of dividing the block of the corresponding node horizontally and a direction of dividing the block of the corresponding node vertically. As shown in fig. 2, when the MTT division starts, a second flag (MTT _split_flag) indicating whether a node is divided, and a flag additionally indicating a division direction (vertical or horizontal) and/or a flag indicating a division type (binary or trigeminal) in the case that a node is divided are encoded by the entropy encoder 155 and signaled to the video decoding apparatus.

Alternatively, a CU partition flag (split_cu_flag) indicating whether a node is partitioned may be further encoded before encoding a first flag (qt_split_flag) indicating whether each node is partitioned into four nodes of a lower layer. When the value of the CU partition flag (split_cu_flag) indicates that each node is not partitioned, the block of the corresponding node becomes a leaf node in the partition tree structure and becomes a CU, which is a basic unit of encoding. When the value of the CU partition flag (split_cu_flag) indicates that each node is partitioned, the video encoding apparatus first starts encoding the first flag in the above scheme.

When QTBT is used as another example of the tree structure, there may be two types, i.e., a type of horizontally dividing a block of a corresponding node into two blocks having the same size (i.e., symmetrical horizontal division) and a type of vertically dividing a block of a corresponding node into two blocks having the same size (i.e., symmetrical vertical division). A partition flag (split_flag) indicating whether each node of the BT structure is partitioned into lower-layer blocks and partition type information indicating a partition type are encoded by the entropy encoder 155 and transmitted to the video decoding apparatus. On the other hand, there may additionally be a type in which a block of a corresponding node is divided into two blocks in an asymmetric form to each other. The asymmetric form may include a form in which a block of a corresponding node is divided into two rectangular blocks having a size ratio of 1:3, or may also include a form in which a block of a corresponding node is divided in a diagonal direction.

A CU may have various sizes according to QTBT or QTBTTT divided from CTUs. Hereinafter, a block corresponding to a CU to be encoded or decoded (i.e., a leaf node of QTBTTT) is referred to as a "current block". When QTBTTT segmentation is employed, the shape of the current block may also be rectangular in shape, in addition to square shape.

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

In general, each of the current blocks in the image may be predictively encoded. In general, prediction of a current block may be performed by using an intra prediction technique using data from an image including the current block or an inter prediction technique using data from an image encoded before the image including the current block. Inter prediction includes both unidirectional prediction and bi-directional prediction.

The intra predictor 122 predicts pixels in the current block by using pixels (reference pixels) located adjacent to the current block in the current image including the current block. Depending on the prediction direction, there are multiple intra prediction modes. For example, as shown in fig. 3a, the plurality of intra prediction modes may include two non-directional modes including a Planar (Planar) mode and a DC mode, and may include 65 directional modes. The neighboring pixels and algorithm equations to be used are defined differently according to each prediction mode.

For efficient direction prediction of a current block having a rectangular shape, direction modes (# 67 to # 80) indicated by dotted arrows in fig. 3b, intra prediction modes # -1 to # -14) may be additionally used. The direction mode may be referred to as a "wide angle intra-prediction mode". In fig. 3b, the arrows indicate the respective reference samples for prediction, rather than representing 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 a direction opposite to a specific direction mode without additional bit transmission. In this case, in the wide-angle intra prediction mode, some of the wide-angle intra prediction modes available for the current block may be determined by a ratio of a width to a height of the current block having a rectangular shape. For example, when the current block has a rectangular shape having a height smaller than a width, wide-angle intra prediction modes (intra prediction modes #67 to # 80) having angles smaller than 45 degrees are available. When the current block has a rectangular shape with a width greater than a height, a wide-angle intra prediction mode having an angle greater than-135 degrees is available.

The intra predictor 122 may determine intra prediction to be used for encoding the current block. In some examples, intra predictor 122 may encode the current block by utilizing a plurality of intra prediction modes, and may also select an appropriate intra prediction mode to use from among the test modes. For example, the intra predictor 122 may calculate a rate distortion value by using rate-distortion (rate-distortion) analysis of a plurality of tested intra prediction modes, and may also select an intra prediction mode having the best rate distortion characteristics among the test modes.

The intra predictor 122 selects one intra prediction mode among a plurality of intra prediction modes, and predicts the current block by using neighboring pixels (reference pixels) determined according to the selected intra prediction mode and an algorithm equation. Information about the selected intra prediction mode is encoded by the entropy encoder 155 and transmitted to a video decoding device.

The inter predictor 124 generates a prediction block of the current block by using a motion compensation process. The inter predictor 124 searches for a block most similar to the current block in a reference picture that has been encoded and decoded earlier than the current picture, and generates a predicted block of the current block by using the searched block. In addition, a Motion Vector (MV) is generated, which corresponds to a displacement (displacement) between a current block in the current image and a prediction block in the reference image. In general, motion estimation is performed on a luminance (luma) component, and a motion vector calculated based on the luminance component is used for both the luminance component and the chrominance component. Motion information including information of the reference picture and information on a motion vector for predicting the current block is encoded by the entropy encoder 155 and transmitted to a video decoding device.

The inter predictor 124 may also perform interpolation of reference pictures or reference blocks to increase the accuracy of prediction. In other words, the sub-samples are interpolated between two consecutive integer samples by applying the filter coefficients to a plurality of consecutive integer samples comprising the two integer samples. When the process of searching for a block most similar to the current block is performed on the interpolated reference image, the decimal-unit precision may be represented for the motion vector instead of the integer-sample-unit precision. The precision or resolution of the motion vector may be set differently for each target region to be encoded, e.g., a unit such as a slice, tile, CTU, CU, etc. In applying such an adaptive motion vector resolution (adaptive motion vector resolution, AMVR), information on the motion vector resolution to be applied to each target area should be signaled for each target area. For example, when the target area is a CU, information about the resolution of a motion vector applied to each CU is signaled. The information on the resolution of the motion vector may be information representing the accuracy of a motion vector difference to be described below.

On the other hand, the inter predictor 124 may perform inter prediction by using bi-directional prediction. In the case of bi-prediction, two reference pictures and two motion vectors representing block positions most similar to the current block in each reference picture are used. The inter predictor 124 selects a first reference picture and a second reference picture from the reference picture list0 (RefPicList 0) and the reference picture list1 (RefPicList 1), respectively. The inter 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. Further, a prediction block of the current block is generated by averaging or weighted-averaging the first reference block and the second reference block. Further, motion information including information on two reference pictures for predicting the current block and information on two motion vectors is transmitted to the entropy encoder 155. Here, the reference image list0 may be constituted by an image preceding the current image in display order among the pre-restored images, and the reference image list1 may be constituted by an image following the current image in display order among the pre-restored images. However, although not particularly limited thereto, a pre-restored image following the current image in the display order may be additionally included in the reference image list 0. Conversely, a pre-restored image preceding the current image may be additionally included in the reference image list 1.

In order to minimize the amount of bits consumed for encoding motion information, various methods may be used.

For example, when a reference image and a motion vector of a current block are identical to those of a neighboring block, information capable of identifying the neighboring block is encoded to transmit motion information of the current block to a video decoding apparatus. This method is called merge mode (merge mode).

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.

As the neighboring blocks used to derive the merge candidates, 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 image may be used, as shown in fig. 4. In addition, in addition to the current picture in which the current block is located, a block located within 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 a merging candidate. For example, a co-located block (co-located block) of a current block within a reference picture or a block adjacent to the co-located block may additionally be used as a merging candidate. If the number of merging candidates selected by the above method is less than a preset number, a zero vector is added to the merging candidates.

The inter predictor 124 configures a merge list including a predetermined number of merge candidates by using neighboring blocks. A merge candidate to be used as motion information of the current block is selected from among the merge candidates included in the merge list, and merge index information for identifying the selected candidate is generated. The generated merging index information is encoded by the entropy encoder 155 and transmitted to a video decoding apparatus.

The merge skip mode is a special case of the merge mode. After quantization, when all transform coefficients used for entropy coding are near zero, only neighboring block selection information is transmitted without transmitting a residual signal. By using the merge skip mode, relatively high encoding efficiency can be achieved for images with slight motion, still images, screen content images, and the like.

Hereinafter, the merge mode and the merge skip mode are collectively referred to as a merge/skip mode.

Another method for encoding motion information is advanced motion vector prediction (advanced motion vector prediction, AMVP) mode.

In the AMVP mode, the inter predictor 124 derives a motion vector prediction candidate for a motion vector of a current block by using neighboring blocks of the current block. As the neighboring blocks used to derive the motion vector prediction candidates, all or some of the left block A0, the lower left block A1, the upper side block B0, the upper right block B1, and the upper left block B2 adjacent to the current block in the current image shown in fig. 4 may be used. In addition, in addition to the current picture in which the current block is located, a block located within a reference picture (which may be the same as or different from a reference picture used to predict the current block) may also be used as a neighboring block used to derive a motion vector prediction candidate. For example, a co-located block of the current block within the reference picture or a block adjacent to the co-located block may be used. If the number of motion vector candidates selected by the above method is less than a preset number, a zero vector is added to the motion vector candidates.

The inter predictor 124 derives a motion vector prediction candidate by using the motion vector of the neighboring block, and determines a motion vector prediction of the motion vector of the current block by using the motion vector prediction candidate. In addition, a motion vector difference is calculated by subtracting a motion vector prediction from a motion vector of the current block.

Motion vector prediction may be obtained by applying a predefined function (e.g., median and average calculations, etc.) to the motion vector prediction candidates. In this case, the video decoding device is also aware of the predefined function. Further, since the neighboring block used to derive the motion vector prediction candidates is a block for which encoding and decoding have been completed, the video decoding apparatus may also already know the motion vector of the neighboring block. Therefore, the video encoding device does not need to encode information for identifying motion vector prediction candidates. Accordingly, in this case, information on a motion vector difference and information on a reference image for predicting a current block are encoded.

On the other hand, motion vector prediction may also be determined by selecting a scheme of any one of the motion vector prediction candidates. In this case, the information for identifying the selected motion vector prediction candidates is additionally encoded together with the information about the motion vector difference and the information about the reference picture for predicting the current block.

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

The transformer 140 transforms a residual signal in a residual block having pixel values of a spatial domain into transform coefficients of a frequency domain. The transformer 140 may transform a residual signal in a residual block by using the entire size of the residual block as a transform unit, or may divide the residual block into a plurality of sub-blocks and perform the transform by using the sub-blocks as transform units. Alternatively, the residual block is divided into two sub-blocks, i.e., a transform region and a non-transform region, to transform the residual signal by 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 a horizontal axis (or a vertical axis). In this case, a flag (cu_sbt_flag) indicating that only the sub-block is transformed, and direction (vertical/horizontal) information (cu_sbt_horizontal_flag) and/or position information (cu_sbt_pos_flag) are encoded by the entropy encoder 155 and signaled to the video decoding apparatus. 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) dividing the corresponding division is additionally encoded by the entropy encoder 155 and signaled to the video decoding device.

On the other hand, the transformer 140 may perform transformation of the residual block separately in the horizontal direction and the vertical direction. For this transformation, various types of transformation functions or transformation matrices may be used. For example, the pair-wise transformation function for horizontal and vertical transformations may be defined as a transformation set (multiple transform set, MTS). The transformer 140 may select one transform function pair having the highest transform efficiency in the MTS and transform the residual block in each of the horizontal and vertical directions. Information (mts_idx) about the transform function pairs in the MTS is encoded by the entropy encoder 155 and signaled to the video decoding means.

The quantizer 145 quantizes the transform coefficient output from the transformer 140 using a quantization parameter, and outputs the quantized transform coefficient 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 positions of the transform coefficients in the transform block. A quantization matrix applied to quantized transform coefficients arranged in two dimensions may be encoded and signaled to a video decoding apparatus.

The reordering unit 150 may perform the rearrangement of the coefficient values on the quantized residual values.

The rearrangement unit 150 may change the 2D coefficient array to a 1D coefficient sequence by using coefficient scanning. For example, the rearrangement unit 150 may scan the DC coefficients to the coefficients of the high frequency region using zigzag scanning (zig-zag scan) or diagonal scanning (diagonal scan) to output a 1D coefficient sequence. Instead of the zig-zag scan, 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 utilized, depending on the size of the transform unit and the intra prediction mode. In other words, the scanning method to be used may be determined in zigzag scanning, diagonal scanning, vertical scanning, and horizontal scanning according to the size of the transform unit and the intra prediction mode.

The entropy encoder 155 encodes the sequence of the 1D quantized transform coefficients output from the rearrangement unit 150 by using various encoding schemes including Context-based adaptive binary arithmetic coding (Context-based Adaptive Binary Arithmetic Code, CABAC), exponential golomb (Exponential Golomb), and the like to generate a bitstream.

Further, the entropy encoder 155 encodes information related to block division (e.g., CTU size, CTU division flag, QT division flag, MTT division type, MTT division direction, etc.) so that the video decoding apparatus can divide blocks equally to the video encoding apparatus. Further, the entropy encoder 155 encodes information on a prediction type indicating whether the current block is encoded by intra prediction or inter prediction. The entropy encoder 155 encodes intra prediction information (i.e., information about an intra prediction mode) or inter prediction information (a merge index in the case of a merge mode, and information about a reference picture index and a motion vector difference in the case of an AMVP mode) according to a prediction type. Further, the entropy encoder 155 encodes information related to quantization (i.e., information about quantization parameters and information about quantization matrices).

The inverse quantizer 160 inversely quantizes the quantized transform coefficient output from the quantizer 145 to generate a transform coefficient. The inverse transformer 165 transforms the transform coefficients output from the inverse quantizer 160 from the frequency domain to the spatial domain to restore a residual block.

The adder 170 adds the restored residual block and the prediction block generated by the predictor 120 to restore the current block. The pixels in the restored current block may be used as reference pixels when intra-predicting the next block.

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

Deblocking filter 182 filters boundaries between restored blocks to remove block artifacts (blocking artifacts) that occur due to block unit encoding/decoding, and SAO filter 184 and ALF 186 additionally filter the deblock filtered video. The SAO filter 184 and ALF 186 are filters for compensating for differences between restored pixels and original pixels that occur due to lossy coding (loss coding). The SAO filter 184 applies an offset as a CTU unit to enhance subjective image 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 boundaries of respective blocks and the degree of variation. Information about filter coefficients to be used for ALF may be encoded and signaled to the video decoding apparatus.

The restored 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 image are restored, the restored image may be used as a reference image for inter-predicting blocks within a picture to be subsequently encoded.

Fig. 5 is a functional block diagram of a video decoding apparatus in which the techniques of the present invention may be implemented. Hereinafter, with reference to fig. 5, a video decoding apparatus and components of the apparatus are described.

The video decoding apparatus may include an entropy decoder 510, a reordering unit 515, an inverse quantizer 520, an inverse transformer 530, a predictor 540, an adder 550, a loop filtering unit 560, and a memory 570.

Similar to the video encoding apparatus of fig. 1, each component of the video decoding apparatus may be implemented as hardware or software, or as a combination of hardware and software. In addition, the function of each component may be implemented as software, and the microprocessor may also be implemented to execute the function of the software corresponding to each component.

The entropy decoder 510 extracts information related to block segmentation by decoding a bitstream generated by a video encoding apparatus to determine a current block to be decoded, and extracts prediction information required to restore the current block and information on a residual signal.

The entropy decoder 510 determines the size of CTUs by extracting information about the CTU size from a Sequence Parameter Set (SPS) or a Picture Parameter Set (PPS), and partitions a picture into CTUs having the determined size. Further, the CTU is determined as the highest layer (i.e., root node) of the tree structure, and the division information of the CTU may be extracted to divide the CTU by using the tree structure.

For example, when dividing a CTU by using the QTBTTT structure, first a first flag (qt_split_flag) related to the division of QT is extracted to divide each node into four nodes of the lower layer. In addition, a second flag (MTT _split_flag), a split direction (vertical/horizontal), and/or a split type (binary/trigeminal) related to the split of the MTT are extracted with respect to a node corresponding to the leaf node of the QT to split the corresponding leaf node into the MTT structure. As a result, each node below the leaf node of QT is recursively partitioned into BT or TT structures.

As another example, when a CTU is divided by using the QTBTTT structure, a CU division flag (split_cu_flag) indicating whether to divide the CU is extracted. When the corresponding block is partitioned, a first flag (qt_split_flag) may also be extracted. During the segmentation process, recursive MTT segmentation of 0 or more times may occur after recursive QT segmentation of 0 or more times for each node. For example, for CTUs, MTT partitioning may occur immediately, or conversely, QT partitioning may occur only multiple times.

As another example, when dividing the CTU by using the QTBT structure, a first flag (qt_split_flag) related to the division of QT is extracted to divide each node into four nodes of the lower layer. In addition, a split flag (split_flag) indicating whether or not a node corresponding to a leaf node of QT is further split into BT and split direction information are extracted.

On the other hand, when the entropy decoder 510 determines the current block to be decoded by using the partition of the tree structure, the entropy decoder 510 extracts information on a 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 for intra prediction information (intra prediction mode) of the current block. When the prediction type information indicates inter prediction, the entropy decoder 510 extracts information representing syntax elements of the inter prediction information, i.e., a motion vector and a reference picture to which the motion vector refers.

Further, the entropy decoder 510 extracts quantization-related information and extracts information on transform coefficients of the quantized current block as information on a residual signal.

The reordering unit 515 may change the sequence of the 1D quantized transform coefficients entropy-decoded by the entropy decoder 510 into a 2D coefficient array (i.e., block) again in the reverse order of the coefficient scan order performed by the video encoding device.

The inverse quantizer 520 inversely quantizes the quantized transform coefficient and inversely quantizes the quantized transform coefficient by using a quantization parameter. 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 of quantized coefficients (scaled values) from the video encoding device to a 2D array of quantized transform coefficients.

The inverse transformer 530 restores a residual signal by inversely transforming the inversely quantized transform coefficients from the frequency domain to the spatial domain to generate a residual block of the current block.

Further, 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) transforming only the sub-block of the transform block, 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 transform coefficients of the corresponding sub-block from the frequency domain to the spatial domain to restore a 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 of the current block.

Further, when applying MTS, the inverse transformer 530 determines a transform index or a transform matrix to be applied in each of the horizontal direction and the vertical direction by using MTS information (mts_idx) signaled from the video encoding apparatus. The inverse transformer 530 also performs inverse transformation on the transform coefficients in the transform block in the horizontal direction and the vertical direction by using the determined transform function.

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.

The intra predictor 542 determines an intra prediction mode of the current block among the plurality of intra prediction modes according to syntax elements 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 an intra prediction mode.

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

The adder 550 restores the current block by adding the residual block output from the inverse transformer 530 to the prediction block output from the inter predictor 544 or the intra predictor 542. In intra prediction of a block to be decoded later, pixels within the restored current block are used as reference pixels.

The loop filtering unit 560, which is an in-loop filter, may include a deblocking filter 562, an SAO filter 564, and an ALF 566. Deblocking filter 562 performs deblocking filtering on boundaries between restored blocks to remove block artifacts occurring due to block unit decoding. The SAO filter 564 and ALF 566 perform additional filtering on the restored block after deblocking filtering to compensate for differences between restored pixels and original pixels that occur due to lossy encoding. The filter coefficients of the ALF are determined by using information on the filter coefficients decoded from the bitstream.

The restored 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 image are restored, the restored image may be used as a reference image for inter-predicting blocks within a picture to be subsequently encoded.

In some embodiments, the invention relates to encoding and decoding video imagery as described above. More particularly, the present invention provides a video encoding and decoding method and apparatus that performs deblocking filtering using segmentation information of an image to avoid filtering at boundaries of objects within the image.

The following embodiments may be applied to the deblocking filter 182 within the loop filtering unit 180 of a video encoding device. Furthermore, the implementation may be applied to a deblocking filter 562 within a loop filtering unit 560 of a video decoding device.

In the following description, the term "target block" to be encoded/decoded may be used interchangeably with the current block or Coding Unit (CU) as described above, or the term "target block" may refer to some region of the coding unit.

In the following description, the operation of the deblocking filter will be described with reference to a luminance block including luminance samples. On the other hand, deblocking filtering can be performed on chroma blocks by employing similar operations.

Furthermore, deblocking filtering is used in compatibility with deblocking, and deblocking filter is used in compatibility with deblocking filtering means.

I. Deblocking filter

As described above, the deblocking filter filters boundaries between restored blocks to remove block artifacts caused by encoding/decoding on a per block basis. The main cause of block artifacts is the difference between the average sample values of neighboring blocks. Deblocking filters aim to achieve smooth transitions across block boundaries while preserving natural edges. In general, whether a boundary is considered a natural edge depends on a Quantization Parameter (QP). For example, a low value of QP may indicate the presence of a natural edge with a small magnitude.

Fig. 6 is a block diagram showing an deblocking filtering apparatus.

As shown in fig. 6, in a multi-functional video codec (VVC) technique, the deblocking filtering apparatus includes all or part of a boundary and filter length determining unit 602, a boundary strength calculating unit 604, a deblocking determining unit 606, and a deblocking performing unit 608.

The boundary and filter length determination unit 602 determines a filter boundary to which deblocking can be applied in the restored area, and determines an initial value of the deblocking filter length for each filter boundary. Here, the restored region may be an image, a slice, or a plurality of CUs.

Deblocking may be applied to boundaries between CUs and TUs based on a 4 x 4 grid. In the case of luma blocks, deblocking may be applied to boundaries between Prediction Units (PUs) in 8×8 grid-based CUs. Here, a PU represents a sub-block within a CU, which uses affine mode or sub-block-based temporal motion vector prediction (SbTMVP) mode.

On the other hand, when a block boundary in the filter boundary overlaps with an image boundary, deblocking may not be applied. Furthermore, deblocking may not be applied when the block boundary overlaps with the boundary of a sub-image, tile or slice, but in-loop filtering is not performed at the respective boundary of a sub-image, tile or slice.

As shown in fig. 7, the filter length represents the number of samples to which deblocking filtering is applied to blocks P and Q adjacent to the filtering boundary. In the following description, the filter length and the deblocking length are used interchangeably. In addition, the filter lengths of the P block and the Q block are denoted as S, respectively _P And S is _Q 。S _P And S is _Q Each of the values depends on the size of the side of the block perpendicular to the boundary between the P block and the Q block.

At the CU/TU boundary, when the size of the side of the CU/TU block is 32 or more, S _P And S is _Q Initialized to 7, S when the size is 4 or less _P And S is _Q Initialized to 1, in other cases S _P And S is _Q Initialized to 3. Furthermore, when using PUs within a CU, S at the CU/TU boundary _P Initialized to min (5,S) _P ) And S is _Q Initialized to min (5,S) _Q ). Furthermore, when the difference between the CU/TU boundary and the PU boundary is 4, S _P And S is _Q Initialized to 1, when the difference is 8, S _P And S is _Q Initialized to 2, in other cases S _P And S is _Q Initialized to 3. In a subsequent step of determining the deblocking of each P/Q region, the filter length can be further reduced.

On the other hand, the example of fig. 7 shows a vertical boundary between the P block and the Q block, and a horizontal boundary between the P block and the Q block may be represented by using rotation and index change of 90 degrees. Accordingly, the filtering boundary may be horizontal or vertical. Deblocking filtering may be performed first on all vertical boundaries within an image, slice, or multiple CTUs, and then filtering may be performed on horizontal boundaries.

In the following description, although the filtering at the vertical boundary is described using the example of fig. 8, the same filtering can be applied to the horizontal boundary by rotating the application direction of the pixels.

The boundary strength calculation unit 604 calculates the boundary strength (boundary strength, bS) of the determined filter boundary. bS may have a value of 0, 1 or 2, and when bs=0, deblocking filtering is not applied.

As shown in fig. 8, bS is determined for boundary portions of the lengths of four samples. In the following description, the P region and the Q region represent two regions of a boundary portion. The P region may be all or part of a P block and the Q region may be all or part of a Q block. The boundary portion may be all or part of the boundary between the P block and the Q block.

On the other hand, in the example of fig. 8, the degree of spatial variation of the first line (line 0) and the last line (line 3) of the P region and the Q region can be used to determine deblocking in a subsequent step.

The bS may be determined according to the codec characteristics of the P region and the Q region. For example, when both the P region and the Q region are intra-coded, bS is set to 2. When both the P region and the Q region are inter-coded and the difference between the motion vectors is greater than or equal to a predetermined value, or the P region or the Q region has a transform coefficient different from 0, bS is set to 1. When the P region and the Q region use Block-level differential pulse code modulation (BPPCM), bS is set to 0. When the P region and the Q region use a Combined Intra/Inter Prediction (CIIP) mode, bS is set to 2. When the P and Q regions use Intra block copy (Intra-Picture Block Copy, IBC) mode, bS is set to 1. On the other hand, bS may be set to 0 for other unspecified cases.

In the case of having a boundary portion whose bS value is not 0, the deblocking determination unit 606 determines whether to apply filtering and the type of deblocking filter based on the degree of spatial variation in the P region and the Q region on both sides of the boundary portion.

Deblocking determination unit 606 first derives t _c And β, which are QP dependent parameters. Generally, by increasing β and t as QP increases _c In the presence of natural edges, the application of deblocking filtering may be suppressed. By limiting the t of clipping (clipping) _c To adjust the smoothing amount for deblocking filtering to makeThe filtered value is not deviated from the value before filtering.

When S is _P Or S _Q Above 3, the deblocking determination unit 606 examines the extent of spatial variation at the boundary to determine the applicability of the long filter. In another case, i.e. when S _P And S is _Q Less than or equal to 3, the deblocking determination unit 606 examines the extent of spatial variation at the boundary to determine the applicability of the short filter. According to the conditions represented by equations 1 to 4, a short filter may be selected.

[ equation 1]

dPQ ₀ +dPQ ₃ ＜β

[ equation 2]

2dPQ _i ＜thr1

[ equation 3]

sP _i +sQ _i ＜thr2

[ equation 4]

|p _0，i -q _0，i |<2.5t _c

In the above equation, i is 0 or 3, and as described above, the degree of spatial variation can be checked by using the lines 0 and 3 of the P region and the Q region. dPQ _i Is an element for checking natural edges, which is defined as dP _i And dQ _i And (3) summing. dP _i And dQ _i Respectively defined as |p _0，i -2p _1，i +p _2，i |and|q _0，i -2q _1，i +q _2，i |。sP _i And sQ _i Are elements for checking the flatness of signals, which are defined as |p, respectively _0，i -p _3，i |and|q _0，i -q _3，i | a. The invention relates to a method for producing a fibre-reinforced plastic composite. The thresholds thr1 and thr2 are defined as β/4 and β/8. The left side of equation 4 represents an element for checking flatness between the P region and the Q region.

S only when the condition represented by equation 1 is satisfied _P And S is _Q Is determined to be 1 or 2 and short and weak filters are selected. Further, when all the conditions represented by equations 1 to 4 are satisfied, S _P And S is _Q Can be determined to be 3 and short and strong filters can be selected. When even the condition of equation 1 is not foundWhen satisfied, deblocking filtering is not applied to the corresponding boundary.

For long filters, the elements used in equations 1 through 4 are modified to include more samples. When S is _P If the dP is greater than 3 _i And sP _i Become further respectively dependent on |p _3，i -2p _4，i +p _5，i I and I p _3，i -ps _p，i | a. The invention relates to a method for producing a fibre-reinforced plastic composite. In addition, when S _P At 7, calculate sP _i Use |p additionally _4，i -p _5，i -P _6，i +p _7，i | a. The invention relates to a method for producing a fibre-reinforced plastic composite. When S is _Q Above 3, dQ can be similarly modified _i And sQ _i 。

To avoid excessive smoothing of the long filter, thr1 and thr2 are changed to β/16 and 3β/32, respectively. When all the conditions represented by equations 1 to 4 reflecting the changed conditions are satisfied, a long filter is selected. On the other hand, if any of the conditions of equations 1 to 4 reflecting the changed condition is not satisfied, the deblocking determining unit 606 reverts to selecting the short filter as described above.

In applying the deblocking filtering, the deblocking performing unit 608 performs the deblocking filtering with filters selected for the P region and the Q region. At this time, deblocking filtering may be performed on four lines (0.ltoreq.i.ltoreq.3) for which the degree of spatial variation has been confirmed.

At S _P Or S _Q Greater than 3 and selecting a long filter, the deblocking performing unit 608 performs deblocking on samples P in the P region using a predetermined linear filter _j，i (0≤j＜S _p ) And sample Q in the Q region _j，i (0≤j＜S _Q ) Deblocking filtering is performed. The coefficients of the preset linear filter may be shared between the video encoding apparatus and the video decoding apparatus.

At S _P And S is _Q 3, and selecting the short and strong filters, the deblocking performing unit 608 uses a predetermined linear filter for the samples P in the P region _j，i (0≤j＜S _p ) And sample Q in the Q region _j，i (0≤j＜S _Q ) Deblocking filtering is performed. The coefficients of the preset linear filter may be shared between the video encoding apparatus and the video decoding apparatus.

In selecting the short and weak filters, the deblocking performing unit 608 performs a predetermined method on the samples P in the P region _j，i (0≤j＜S _p ) And sample Q in the Q region _j，i (0≤j＜S _Q ) Deblocking filtering is performed. At this time, S _P And S is _Q May be 1 or 2. The predetermined method may be shared between the video encoding apparatus and the video decoding apparatus.

Deblocking filter using segmentation information

In the following description, a deblocking filter for more closely reflecting object boundaries in natural edges within an image and a method according to the deblocking filter are described.

The deblocking filtering apparatus according to the present embodiment uses the segmentation information of the image to avoid filtering at object boundaries in the image. The deblocking filtering apparatus includes all or part of a segmentation execution unit 902, a boundary and filter length determination unit 602, a boundary strength calculation unit 604, a filter length adjustment unit 904, a deblocking determination unit 606, and a deblocking execution unit 608.

After restoring an image, a slice, or a plurality of CUs, the partition performing unit 902 performs partition on the restored region to partition the region into individual objects, and generates partition information about the objects. The partition performing unit 902 may output a map in which a corresponding index is allocated to each object on a per pixel basis as partition information. The segmentation may be equally performed in the video encoding apparatus and the video decoding apparatus.

The segmentation execution unit 902 may execute segmentation based on a boundary detection method, a region separation method, a clustering method, or the like within an image. Alternatively, the segmentation may be performed based on a network consisting of single or multiple convolutional layers. The segmentation performing unit 902 may obtain the number of objects on a per image or slice basis, and then may segment the image into as many sub-images as the number of objects. For example, the partition performing unit 902 in the video encoding apparatus may obtain the number of objects from a high-level, and the partition performing unit 902 in the video decoding apparatus may decode the number of objects from a bitstream.

On the other hand, the video encoding apparatus may transmit a flag indicating whether or not to perform segmentation, i.e., a segmentation application flag, to the video decoding apparatus on a per slice or CU basis. After parsing the segmentation application flag, the video decoding apparatus may or may not perform segmentation according to the true/false value of the flag. Alternatively, the video decoding apparatus may derive whether to perform segmentation according to a previous protocol.

The video decoding apparatus may determine the segmentation application flag as follows. In the following description, an original slice, an original CU, or an original CU group is denoted as an original region, and a restored slice, a restored CU, or a restored CU group is denoted as a restored region. When the same segmentation method is performed on the original region and the restored region, respectively, and a pixel difference as large as a predetermined threshold appears between segmentation results from the original region and the restored region, the video encoding apparatus may indicate that segmentation is not performed by setting a segmentation application flag of the corresponding slice or CU to false.

The video decoding device may derive whether to perform partitioning on a per slice, CU, or CTU basis. For any slice, when the base QP of the slice is greater than a predetermined reference value, or the average QP of the CUs within the slice is greater than a predetermined reference value, no segmentation may be performed on the corresponding slice. On the other hand, when the base QP or the average QP is equal to or smaller than a predetermined reference value, segmentation may be performed. Alternatively, for each CTU, when the average QP of the plurality of CUs in the CTU is greater than a predetermined reference value, the segmentation may not be performed on the CTU, and when the average QP is equal to or less than the predetermined reference value, the segmentation may be performed. Alternatively, for each CU, when the QP of the CU is greater than a predetermined reference value, the partitioning may not be performed on the coding unit, and when the QP of the CU is equal to or less than the predetermined reference value, the partitioning may be performed.

On the other hand, when the segmentation is not performed on a slice or CU, a subsequent step of utilizing the segmentation result may not be performed on the corresponding slice or CU.

As described above, the boundaryAnd a filter length determination unit 602 determines a filter boundary in a restored region to which deblocking can be applied, and initializes a deblocking filter length S for the corresponding filter boundary _P And S is _Q . For adjacent blocks P and Q of the filtering boundary shown in fig. 7, the filter length represents the number of samples to which deblocking filtering is applied.

The filter length adjustment unit 904 determines whether to perform deblocking filtering by using the division result, and adjusts the deblocking filter length S _P And S is _Q . At this time, the filter length adjustment unit 904 may apply the division result to P and Q regions of size mxn, which are adjacent to a boundary portion of sample length N (where N is a natural number) and contain M (where M is a natural number) samples perpendicular to the boundary, as shown in fig. 10. For example, in the example of fig. 10, m=8, and n=4 for the P region and the Q region adjacent to the vertical boundary.

As described above, the filtering boundary may have a horizontal or vertical direction. In this embodiment, deblocking filtering may be performed first on all boundaries in the vertical direction within an image, slice, or multiple CTUs. Alternatively, deblocking filtering may be performed first on all boundaries in the horizontal direction. In another embodiment, deblocking filtering may be performed on horizontal and vertical boundaries in a particular order.

In the following description, although a description is given based on filtering at a boundary in the vertical direction using the example of fig. 10, the same filtering can be applied to a boundary in the horizontal direction by rotating the application direction of the pixel.

In the following description, a process of determining whether to apply deblocking filtering according to a division result by the filter length adjustment unit 904 is described. The filter length adjustment unit 904 evaluates the condition a, the condition B, and the condition C of each line of N samples (0+.n < N), and performs determination of whether deblocking is performed at the current deblocking boundary, setting of a boundary sub-group, and adjustment of the filter length by collecting the evaluation result of each line. In the following condition, the following relationship holds: k (k) ₀ ＜k ₁ ＜k ₂ ＜M。

(condition A) p _0，n And q _0.n Included in the same object.

(condition B) falls within the range (0 < m.ltoreq.k) ₀ ) Each p of (2) _m，n And p is as follows _0，n Are included together in the same object and belong to the range (0 < m.ltoreq.k ₀ ) Each q of (2) _m，n And q _0，n Together included in the same object.

(condition C) falls within the range (0 < m.ltoreq.k) ₀ )、(0＜m≤k ₁ ) Or (m is more than 0 and less than or equal to k) ₂ ) Each p of (2) _m，n And p is as follows _0，n Are included together in the same object and belong to the range (0 < m.ltoreq.k ₀ )、(0＜m≤k ₁ ) Or (m is more than 0 and less than or equal to k) ₂ ) Each q of (2) _m，n And q _0，n Together included in the same object. However, the same case as condition B is excluded.

If the number of consecutive lines sub_row_num satisfying the conditions A and B is smaller than the minimum number of lines min_row_num, and p of the corresponding line _0，n Not all included in the same object, deblocking filtering is not applied to the boundary between the current P region and the Q region. In this case, by considering that the object boundary exists in the range (0.ltoreq.m.ltoreq.k ₀ ) In the P region or in the range (0.ltoreq.m.ltoreq.k) ₀ ) No deblocking filtering is applied in the Q region of (c).

Here, the minimum line number min_row_num may be transmitted from the video encoding apparatus or predefined by the same value in advance between the video encoding apparatus and the video decoding apparatus.

On the other hand, when the condition a and B or the condition a and C is satisfied, the number of continuous lines sub_row_num is greater than or equal to the minimum number of lines min_row_num, and p of the corresponding line _0，n When all belong to the same object, the filter length adjustment unit 904 sets the region including the corresponding sub_row_num line and boundary as a deblocking sub-region and a deblocking sub-boundary. Further, the filter length adjustment unit 904 adjusts the size on the left side of the deblocking sub-boundary to sub_row_num× (k ^P +1) is set as the P sub-region, and the size on the right side of the deblocking sub-boundary is sub_row_num× (k) ^Q The region of +1) is set to the Q subregion. Here, k ^P And k ^Q Is defined asFilter lengths of P sub-region and Q sub-region. In the present embodiment, deblocking filtering may be performed on pixels within the deblocking sub-region (i.e., pixels within the P sub-region and the Q sub-region) belonging to the same object.

In addition, when there are a plurality of P sub-region and Q sub-region pairs for the deblocking sub-boundary determined as described above, the filter length adjustment unit 904 may select the P sub-region and Q sub-region pairs, which may generate (k) ^P +k ^Q + sub_row_num). At this time, the maximum P sub-region may be the same as the P region, and the maximum Q sub-region may be the same as the Q region. Accordingly, the length of the longest sub-boundary may be the length of the boundary between the P region and the Q region, i.e., N samples.

In the following description, k is used for the deblocking sub-boundary determined as described above ^P And k ^Q Determining and adjusting the deblocking filter length S accordingly _P And S is _Q Is described.

When conditions A and B are satisfied but condition C is not satisfied, k ^P And k ^Q The value of (c) may be k ₀ . Thus, deblocking filter length S _P Can be set to min (k ₀ ，S _P ) And S is _Q Can be set to min (k ₀ ，S _Q ). In other words, when S _P The previous value of less than k ₀ Or S _Q The value of (2) is less than k ₀ When the value may remain as it is.

When conditions A and C are satisfied, k ^P The value of (c) may be k ₀ 、k ₁ Or k ₂ And k is ^Q The value of (c) may be k ₀ 、k ₁ Or k ₂ . However, exclude k ^P ＝k ₀ And k is ^Q ＝k ₀ Is the case in (a). Thus, deblocking filter length S _P Can be set to min (k ^P ，S _P ) And S is _Q Can be set to min (k ^Q ，S _P ). In other words, when S _P The previous value of less than k ^P Or S _Q The value of (2) is less than k ^Q When the value may remain as it is.

Deblocking filterLength S _P And S is _Q May be different from each other.

Fig. 11a to 11c illustrate sub-regions using segmentation results according to an embodiment of the present invention.

In the examples of fig. 11a to 11c, min_row_num=3, k ₀ ＝3，k ₁ =5, and k ₂ =7. Further, the examples of fig. 11a to 11C show objects A, B and C. The example of fig. 11a shows the deblocking filter length S _P Or S _Q A sub-region greater than 3, wherein a long filter may be applied after the P sub-region and the Q sub-region. The example of fig. 11b shows the deblocking filter length S _P And S is _Q A subregion shorter than or equal to 3, wherein a short filter can be applied after the P subregion and the Q subregion. The example of fig. 11c shows the segmentation result without the application of deblocking filtering.

The boundary strength calculation unit 604 calculates the boundary strength bS of the boundary where deblocking has been determined to be applied. As described above, bS can have a value greater than or equal to 0. When bS is less than or equal to a predetermined threshold (e.g., 0), no deblocking filtering is applied.

bS is determined for a sub-boundary of sample length sub_row_num between the P sub-region and the Q sub-region. The bS may be determined according to the codec characteristics of the P sub-region and the Q sub-region. However, since the bS calculation method according to the codec characteristics of the P region and the Q region can be used in the same manner, further detailed description is omitted.

In the case of a sub-boundary where bS is greater than a predetermined threshold, the deblocking determination unit 606 determines whether to apply filtering and the type of deblocking filter based on the degree of spatial variation in the P sub-region and the Q sub-region on both sides of the sub-boundary.

Deblocking determination unit 606 first derives t _c And β, which are QP dependent parameters.

When S is _P Or S _Q Greater than k ₀ At this time, the deblocking determination unit 606 checks the degree of spatial variation at the sub-boundaries to determine the applicability of the long filter. In another case, i.e. when S _P And S is _Q Less than or equal to k ₀ At this time, the deblocking determination unit 606 checks sub-boundariesThe degree of spatial variation at to determine the applicability of the short filter. According to the conditions represented by equations 5 to 8, a short filter may be selected.

[ equation 5]

dPQ _{n_first} +dPQ _{n_last} ＜β

[ equation 6]

dPQ _n ＜thr1

[ equation 7]

sP _n +sQ _n ＜thr2

[ equation 8]

|p _0，n -q _0，n |＜w ₃ ·t _c

In the above equation, n is n_first or n_last, which represents the first and last lines of the P and Q subregions. In other words, the extent of the spatial variation of the P sub-region and the Q sub-region can be checked by using the first line and the last line.

dPQ _n Is an element for checking natural edges, which is defined as dP _n And dQ _n And (3) summing. dP _n And dQ _n May be defined as a weighted sum of samples, e.g., |p _0，n -2p _1，n +p _2，n |and|q _0，n -2q _1，n +q _2，n |。sP _n And sQ _n Are elements for checking the flatness of the signal, which are defined as weighted sums of samples, e.g., |p _0，n -P _k0，n |and|q _0，n -q _k0，n | a. The invention relates to a method for producing a fibre-reinforced plastic composite. The thresholds thr1 and thr2 may be defined as w, respectively ₁ Beta and w ₂ Beta. The left side of equation 8 is an element for checking flatness between the P sub-region and the Q sub-region. On the other hand, w ₁ 、w ₂ And w ₃ Is a predetermined constant that can be shared between the video encoding device and the video decoding device.

S only when the condition represented by equation 5 is satisfied _P And S is _Q Is determined to be 1 or 2 and short and weak filters are selected. Further, when all the conditions represented by equations 5 to 8 are satisfied, S _P And S is _Q Can be determined as k ₀ And can selectShort and strong filters. When the condition of even equation 5 is not satisfied, deblocking filtering is not applied to the corresponding boundary.

For long filters, the elements used in equations 5 through 8 are modified to include more samples. When S is _P Greater than k ₀ When dP _n And sP _n Become further dependent on the weighted sum of the samples, e.g., |p _k0，n -2p _k0+1，n +P _k0+2，n Sum of IFurther, at S _P Is k ₂ In the case of (1), when calculating sP _n When additionally using a weighted sum of samples, e.g., |c5 _k0+1 ·p _k0+1，n +c5 _k0+2 ·p _k0+2，n +…+c5 _Sp ·p _Sp，n |。c5 _m (k0+1≤m≤S _P ) Is the weight of the weighted sum. When S is _Q Greater than k ₀ dQ can be similarly modified at this time _n And sQ _n 。

To avoid excessive smoothing of the long filter, thr1 and thr2 are changed to w, respectively ₄ Beta and w _s ·β。w ₄ And w ₅ Is a predetermined constant that can be shared between the video encoding device and the video decoding device. When all the conditions represented by equations 5 to 8 reflecting the changed conditions are satisfied, a long filter is selected. On the other hand, if any of the conditions of equations 5 to 8 reflecting the changed condition is not satisfied, the deblocking determining unit 606 reverts to selecting the short filter as described above.

The application of deblocking and the filter length are determined using the first and last lines of the P and Q subregions according to the description above. However, the present invention is not necessarily limited to the above detailed description. In another embodiment, the deblocking determination unit 606 may utilize all or part of the rows of P and Q sub-regions to determine the application of deblocking and the filter length.

In applying the deblocking filtering, the deblocking performing unit 608 performs the deblocking filtering with filters selected for the P sub-region and the Q sub-region. At this time, deblocking filtering may be performed on sub_row_num lines (n_first n.ltoreq.n_last) for which the degree of spatial variation has been confirmed.

When S is _P Or S _Q Greater than k ₀ And selecting the long filter, deblocking unit 608 performs deblocking on samples P in the P sub-region _m，n (0≤m＜S _P ) And sample Q in the Q subregion _m，n (0≤m＜S _Q ) Deblocking filtering is performed as shown in equation 9.

[ equation 9]

p′ _m，n ＝(pM _m ·refM _n +pR _m ·refP _n )＞＞sh

q′ _m，n ＝(qM _m ·refM _n +qR _m ·refQ _n )＞＞sh

Here, in the two equations of equation 9, sh may have different values. All pMs _m 、pR _m 、qM _m And qR _m Is a predetermined coefficient of the long filter and can be shared between the video encoding apparatus and the video decoding apparatus. refP _n P, which can be defined as line n _m，n (0≤m≤S _P ) Wherein n represents a sum of weights from S _P Values in descending order, and refQ _n Q, which can be defined as line n _m，n (0≤m≤S _Q ) Wherein m represents a sum of weights from S _Q Values in descending order. For example, refP _n And refQ _n May be defined by the following equation 10.

[ equation 10]

Here, in both equations of equation 10, sh may have different values.

Furthermore, refM _n At least one p, which may be defined as a line n _m，n (0≤m≤S _P ) (wherein m represents a slave group0 ascending value) and at least one q _m，n (0≤m≤S _Q ) (where m represents a value in ascending order from 0).

When S is _P And S is _Q Is k ₀ And selecting the short and strong filters, deblocking unit 608 performs deblocking on samples P in the P sub-region _m，n (0≤m＜S _P ) And sample Q in the Q subregion _m，n (0≤m＜S _Q ) Deblocking filtering is performed. Deblocking performing unit 608 may perform deblocking by P on line n _m，n (0≤m≤S _P ) And q _m，n (0≤m≤S _Q ) To define the filtered value. For example, deblocking filtering may be performed as shown in equation 11.

[ equation 11]

Here, in both equations of equation 10, sh may have different values. In addition, all pW1 _i 、qW1 _j 、pW2 _i And qW2 _j Is a predetermined coefficient of the strong filter and can be shared between the video encoding apparatus and the video decoding apparatus.

When the short and weak filters are selected, the deblocking unit 608 performs deblocking on samples P in the P sub-region _m，n (0≤m＜S _P ) And sample Q in the Q subregion _m，n (0≤m＜S _Q ) Deblocking filtering is performed. At this time, S _P And S is _Q May have a value of 1 or 2. In the case of short and weak filtering, the application of the filtering can be re-evaluated on a per line basis and on a per pixel basis within a line in the P sub-region and Q sub-region.

At p to line n _0，n And q _0，n Prior to performing filtering, Δ is calculated from equation 12.

[ equation 12]

Δ＝(a·(q _0，n -p _0，n )+b·(q _1，n -p _1，n )+c)＞＞sh

In equation 12, a, b, and c are predetermined constants, and may be shared between the video encoding apparatus and the video decoding apparatus.

When the relation (|delta < w) ₆ ·t _c I) is satisfied, p _0，n And q _0，n Filtering can be performed by equation 13. w (w) ₆ Is a predetermined constant and can be shared between the video encoding apparatus and the video decoding apparatus.

[ equation 13]

p′ _0，n ＝p _0，n +Δ

q′ _0,n ＝q _0，n -Δ

In addition, for p _0，n And q _0，n The line that has been filtered can be evaluated for p _1，n And q _1，n Is included. First, if S _P =2, and (|dp) _{n_first} |+|dP _{n_last} |)＜w ₇ Beta, then p _1，n Filtering can be performed by equation 14. w (w) ₇ Is a predetermined constant and can be shared between the video encoding apparatus and the video decoding apparatus.

[ equation 14]

p′ _1，n ＝p _1，n +Δ _p

Δ _p ＝(((p _2，n +p _0，n )＞＞sh2)-(p _1，n +Δ))＞＞sh

Next, if S _Q =2, and (|dq) _{n_first} |+|dQ _{n_last} |)＜w ₇ Beta, q _1，n Filtering can be performed by equation 15.

[ equation 15]

q′ _1，n ＝q _1，n +Δ _q

Δ _q ＝(((q _2，n +q _0，n )＞＞sh2)-(q _1，n +Δ))＞＞sh

Here, in the equations of equations 13 to 15, sh and sh2 may have different values.

In the following description, a deblocking filtering method applied to a restored area of an image by a deblocking filtering apparatus is described with reference to fig. 12. As described above, the deblocking filtering method can be equally performed between the video encoding apparatus and the video decoding apparatus.

The deblocking filtering apparatus performs segmentation on the restored area to partition the restored area into individual objects, and generates segmentation information of the objects (S1200).

Here, the restored region may be an image, a slice, or a plurality of CUs. Furthermore, the segmentation information of the objects may be a mapping in which each object is assigned a respective index on each pixel of the restored image.

The deblocking filtering apparatus may obtain the number of objects on a per image or slice basis, and then may partition the image into as many sub-images as the number of objects. For example, the deblocking filtering apparatus within the video encoding apparatus may obtain the number of objects from a high level, and the deblocking filtering apparatus within the video decoding apparatus may decode the number of objects from the bitstream.

The deblocking filtering apparatus selects a boundary between CUs and TUs within the restored region as a filtering boundary to which deblocking filtering is applied (S1202). Furthermore, the deblocking filtering means may select a boundary between PUs within the CU as a filtering boundary.

On the other hand, when a block boundary in the filter boundary overlaps with an image boundary, deblocking may not be applied. Furthermore, deblocking may not be applied when the block boundary overlaps a sub-image, tile or slice boundary, but in-loop filtering is not performed at the corresponding sub-image, tile or slice boundary.

For each filtering boundary, the deblocking filtering apparatus initializes the P filter length and the Q filter length of each block adjacent to the filtering boundary (S1204).

As shown in fig. 7, the filter length represents the number of samples to which deblocking filtering is applied to blocks P and Q adjacent to the filtering boundary.

At the CU/TU boundary, when the side of the CU/TU block is 32 in sizeOr greater, P filter length S _P And Q filter length S _Q Initialized to k ₂ When the size is 4 or less, the P filter length S _P And Q filter length S _Q Initialized to 1, in other cases, P filter length S _P And Q filter length S _Q Initialized to k ₀ . Furthermore, when using PUs within a CU, S at the CU/TU boundary _P Initialized to min (k) ₁ ，S _P ) And S is _Q Initialized to min (k) ₁ ，S _Q ). Furthermore, when the difference between the CU/TU boundary and the PU boundary is 4, S _P And S is _Q Initialized to 1, when the difference is 8, S _P And S is _Q Initialized to 2, in other cases S _P And S is _Q Initialized to k ₀ 。

For P and Q regions of a predetermined size adjacent to the filtering boundary, the deblocking filtering apparatus sets P and Q sub-regions belonging to the same object by using the partition information, and adjusts P and Q filter lengths (S1206).

Here, the P region and the Q region represent regions of size mxn, which are adjacent to a boundary portion (boundary segment) of a sample length N in a filtering boundary, and include N lines perpendicular to the boundary portion, each of the N lines including M samples.

When a continuous sub-boundary existing between the P region and the Q region is longer than or equal to a predetermined sample length min_row_num, and a minimum value of the number of samples included in the corresponding line of the P region and the Q region perpendicular to the sub-boundary is greater than or equal to a predetermined threshold (k ₀ +1), the deblocking filtering means performs deblocking filtering. Accordingly, when the sub-boundary is smaller than a predetermined sample length or the minimum number is smaller than a predetermined threshold, deblocking filtering is not performed on the P region and the Q region adjacent to the corresponding sub-boundary.

When performing deblocking filtering, the deblocking filtering means may set the filter length of the P subregion to a predetermined value (k ₀ ，k ₁ ，k ₂ ) Is a member of the group consisting of a metal, a metal alloy. Furthermore, the size of the P sub-region may be determined based on the filter lengths of the consecutive sub-boundaries and the P sub-region. For PSub-region, deblocking filter adjustment S _P Filter length for P subregions and initialized S _P Is a minimum of (2).

In the same manner, when deblocking filtering is performed, the deblocking filtering means may set the filter length of the Q subregion to one of predetermined values according to the minimum number. Furthermore, the size of the Q subregion may be determined based on the filter lengths of the consecutive sub-boundaries and the Q subregion. For the Q subregion, the deblocking filter arrangement adjusts S _Q Filter length for Q subregions and initialized S _Q Is a minimum of (2).

The deblocking filtering apparatus calculates boundary strength of sub-boundaries between the P sub-region and the Q sub-region (S1208). The boundary strength bS may be determined according to the codec characteristics of the P sub-region and the Q sub-region.

The deblocking filtering apparatus checks whether the boundary strength is greater than a predetermined threshold (S1210).

If the boundary strength is less than or equal to a predetermined threshold (e.g., zero) (no in S1210), the deblocking filtering means omits deblocking filtering for the corresponding sub-boundary.

If the boundary strength is greater than the predetermined threshold (yes in S1210), the deblocking filtering apparatus performs the following steps for deblocking filtering of the corresponding sub-boundary.

The deblocking filtering apparatus calculates the degree of spatial variation of the P sub-region and the Q sub-region based on the adjusted P filter length and the Q filter length (S1212).

The deblocking filtering means may calculate the degree of spatial variation using samples of a first line and samples of a last line among lines perpendicular to a sub-boundary between the P sub-region and the Q sub-region. The degree of spatial variation may be used to suppress filtering of natural edges.

The deblocking filtering apparatus determines whether deblocking filtering is applied based on the degree of spatial variation of the P sub-region and the Q sub-region, and determines the type of the deblocking filter when deblocking filtering is applied (S1214). As described above, the deblocking filter may be determined as one of a long filter, short and strong filters, and short and weak filters.

The deblocking filtering apparatus performs deblocking filtering by applying a deblocking filter to the P sub-region and the Q sub-region (S1216).

Although steps in the respective flowcharts are described as sequentially performed, these steps merely exemplify the technical ideas of some embodiments of the present invention. Accordingly, one of ordinary skill in the art to which the invention pertains may perform the steps by changing the order depicted in the various figures or by performing two or more steps in parallel. Accordingly, the steps in the various flowcharts are not limited to the order in which they occur as shown.

It should be understood that the foregoing description presents illustrative embodiments that may be implemented in various other ways. The functions described in some embodiments may be implemented by hardware, software, firmware, and/or combinations thereof. It should also be understood that the functional components described in this specification are labeled "… … units" to highlight the possibility of their independent implementation.

On the other hand, the various methods or functions described in some embodiments may be implemented as instructions stored in a non-volatile recording medium, which may be read and executed by one or more processors. The nonvolatile recording medium may include various types of recording devices that store data in a form readable by a computer system, for example. For example, the nonvolatile recording medium may include a storage medium such as an erasable programmable read-only memory (EPROM), a flash memory drive, an optical disk drive, a magnetic hard disk drive, a Solid State Drive (SSD), and the like.

Although exemplary embodiments of the present application have been described for illustrative purposes, those skilled in the art to which the present application pertains will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the application. Accordingly, embodiments of the present application have been described for brevity and clarity. The scope of the technical idea of the embodiment of the application is not limited by the illustration. Accordingly, it will be understood by those of ordinary skill in the art that the scope of the present application should not be limited by the embodiments explicitly described above, but by the claims and their equivalents.

(reference numerals)

182: deblocking filter

562: deblocking filter

602: filter length determining unit

604: boundary strength calculation unit

606: deblocking determination unit

608: deblocking execution unit

902: segmentation execution unit

904: and a filter length adjustment unit.

Cross Reference to Related Applications

The present application claims priority from korean patent application No.10-2021-0030850, filed on 3 months 9 of 2021, and korean patent application No.10-2022-0027870, filed on 4 months 3 of 2022, each of which is incorporated herein by reference in its entirety.

Claims

1. A method performed by a computing device for applying deblocking filtering to a restored region of an image, the method comprising:

performing segmentation on a restored region to partition the restored region into individual objects, and generating segmentation information of the objects, wherein the restored region is an image, a slice, or a plurality of encoding units;

selecting a boundary between the coding unit and the transform unit in the restored region as a filtering boundary to which deblocking filtering is applied;

initializing, for each filter boundary, a P filter length and a Q filter length for each block adjacent to the filter boundary;

setting a P sub-region and a Q sub-region belonging to the same object using partition information of the P region and the Q region having a predetermined size adjacent to the filtering boundary, and adjusting a P filter length and a Q filter length;

calculating the degree of spatial variation of the P sub-region and the Q sub-region based on the adjusted P filter length and Q filter length;

determining whether to apply deblocking filtering based on the degree of spatial variation of the P sub-region and the Q sub-region, and determining a type of deblocking filter when the deblocking filtering is applied; and

deblocking filtering is performed by applying deblocking filters to the P sub-region and the Q sub-region.

2. The method of claim 1, wherein the partition information of the objects is a map in which each object is assigned a respective index on a per pixel basis.

3. The method of claim 1, further comprising:

obtaining the number of objects in the restored region from a high level or bitstream, wherein

The generation of the segmentation information partitions the restored region into as many sub-regions as the number of objects.

4. The method of claim 1, further comprising:

a flag indicating whether to perform segmentation is obtained from a high level or bitstream,

wherein when the flag is true, segmentation is performed.

5. The method of claim 4, wherein the flag is set to true by the video encoding apparatus when the same segmentation method is performed on the original region and the restored region, respectively, and a pixel difference as large as a predetermined threshold occurs between segmentation results from the original region and the restored region.

6. The method of claim 1, further comprising:

whether to perform the segmentation is deduced by the video decoding means,

wherein the deriving determines to perform the partitioning when the basic quantization parameter of the slice is less than or equal to a predetermined reference value and the average quantization parameter of the coding units within the slice is less than or equal to the predetermined reference value.

7. The method of claim 1, wherein the P region and the Q region represent regions of size mxn, are adjacent to a boundary portion of sample length N in the filtering boundary, and include N lines perpendicular to the boundary portion, each of the N lines including M samples.

8. The method of claim 1, wherein the deblocking filtering is performed when a consecutive sub-boundary existing between the P region and the Q region is longer than or equal to a predetermined sample length, and a minimum value of the number of samples included in a corresponding line of the P region and the Q region perpendicular to the consecutive sub-boundary is greater than or equal to a predetermined threshold.

9. The method of claim 8, wherein deblocking filtering is not performed on P and Q regions adjacent to the respective sub-boundary when the consecutive sub-boundary is less than a predetermined sample length or the minimum number is less than a predetermined threshold.

10. The method of claim 8, wherein when deblocking filtering is performed, the filter length of the P sub-region is set to one of predetermined values according to the minimum number, and the size of the P sub-region is set based on the continuous sub-boundary and the filter length of the P sub-region.

11. The method of claim 10, wherein for a P sub-region, the adjusting adjusts the P filter length to a minimum of the P sub-region's filter length and the initialized P filter length.

12. The method of claim 1, further comprising:

calculating the boundary strength of the sub-boundary between the P sub-region and the Q sub-region,

wherein deblocking filtering is performed on the P sub-region and the Q sub-region adjacent to the respective sub-boundary when the boundary strength is greater than a predetermined threshold.

13. The method of claim 8, wherein the degree of spatial variation is calculated by using samples of a first line and samples of a last line of lines perpendicular to consecutive sub-boundaries in the P sub-region and the Q sub-region.

14. The method of claim 1, wherein the deblocking filter is one of a long filter, a short and strong filter, or a short and weak filter.

15. A deblocking filtering apparatus, comprising:

a division performing unit configured to perform division on a restored region, which is an image, a slice, or a plurality of encoding units, to divide the restored region into individual objects, and generate division information of the objects;

a boundary and filter length determination unit configured to select a boundary between the coding unit and the transform unit within the restored region as a filtering boundary to which deblocking filtering is applied, and initialize a P filter length and a Q filter length of each block adjacent to the filtering boundary for each filtering boundary;

A filter length adjustment unit configured to set a P sub-region and a Q sub-region belonging to the same object using partition information of the P region and the Q region having a predetermined size adjacent to a filtering boundary, and adjust the P filter length and the Q filter length;

a deblocking determination unit configured to calculate degrees of spatial variation of the P sub-region and the Q sub-region based on the adjusted P filter length and Q filter length, determine whether to apply deblocking filtering based on the degrees of spatial variation of the P sub-region and the Q sub-region, and determine a type of the deblocking filter when the deblocking filtering is applied; and

a deblocking performing unit configured to perform deblocking filtering by applying a deblocking filter to the P sub-region and the Q sub-region.

16. The apparatus of claim 15, wherein the deblocking filtering is performed when a consecutive sub-boundary existing between the P region and the Q region is longer than or equal to a predetermined sample length, and a minimum value of the number of samples included in a corresponding line of the P region and the Q region perpendicular to the consecutive sub-boundary is greater than or equal to a predetermined threshold.

17. The apparatus of claim 16, wherein when performing deblocking filtering, the filter length adjustment unit is configured to set the filter length of the P region to one of predetermined values according to the minimum number, and to set the size of the P sub-region based on the continuous sub-boundary and the filter length of the P region.

18. The apparatus of claim 17, wherein for the P sub-region, the filter length adjustment unit is configured to adjust the P filter length to a minimum of the initialized P filter length and the filter length of the P region.

19. The apparatus of claim 15, further comprising:

a boundary strength calculation unit configured to calculate a boundary strength of a sub-boundary between the P sub-region and the Q sub-region,

20. The apparatus of claim 16, wherein the deblocking determination unit is configured to calculate the degree of spatial variation by utilizing samples of a first line and samples of a last line of lines perpendicular to consecutive sub-boundaries in the P sub-region and the Q sub-region.