WO2017142327A1 - 인트라 예측오차의 감소를 위한 인트라 예측 방법 및 그 장치 - Google Patents
인트라 예측오차의 감소를 위한 인트라 예측 방법 및 그 장치 Download PDFInfo
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Definitions
- the present invention relates to an intra prediction method and apparatus for encoding and decoding video, and more particularly, to an intra prediction method and apparatus for adjusting a reference sample referenced by a current sample according to a distance between a current sample and a reference sample. It is about.
- High quality video requires a large amount of data during encoding.
- the bandwidth allowed for delivering video data is limited, so that the data rate applied when transmitting video data may be limited. Therefore, in order to efficiently transmit video data, there is a need for a method of encoding and decoding video data having increased compression ratio while minimizing degradation of image quality.
- Video data can be compressed by removing spatial redundancy and temporal redundancy between pixels. Since it is common to have a common feature among adjacent pixels, encoding information is transmitted in a data unit composed of pixels to remove redundancy between adjacent pixels.
- the pixel values of the pixels included in the data unit are not transmitted directly, but a method necessary for obtaining the pixel value is transmitted.
- a prediction method for predicting the pixel value similar to the original value is determined for each data unit, and encoding information about the prediction method is transmitted from the encoder to the decoder. Also, since the predicted value is not exactly the same as the original value, residual data about the difference between the original value and the predicted value is transmitted from the encoder to the decoder.
- the prediction method is determined in consideration of the size of the encoding information and the residual data.
- a data unit divided in a picture has various sizes. As the size of the data unit is larger, the accuracy of prediction is more likely to decrease, but encoding information is reduced. Therefore, the size of the block is determined according to the characteristics of the picture.
- Prediction methods also include intra prediction and inter prediction.
- Intra prediction is a method of predicting pixels of a block from neighboring pixels of the block.
- Inter prediction is a method of predicting pixels by referring to pixels of another picture referred to by a picture including a block. Therefore, spatial redundancy is removed by intra prediction and temporal redundancy is removed by inter prediction.
- the encoded information applied to the block may also be predicted from another block to reduce the size of the encoded information.
- the residual data may be lossy compressed according to a transformation and quantization process to reduce the amount of residual data.
- An intra prediction method for adjusting a reference sample according to a distance between a current sample and a reference sample to increase the prediction accuracy of the current sample is disclosed.
- an intra prediction apparatus for performing the intra prediction method is disclosed.
- a computer-readable recording medium recording a program for executing the intra prediction method in a computer is disclosed.
- a neighboring sample acquisition unit for obtaining a plurality of neighboring samples located in the vicinity of the current block, and a reference sample for determining a neighboring sample indicated by the direction of the intra mode of the current block among the plurality of neighboring samples as a reference sample to which the current sample refers.
- an image prediction apparatus including a determiner and a predictor configured to adjust the reference sample according to a reference distance representing a distance between the reference sample and the current sample and predict the current sample according to the adjusted reference sample.
- the reference sample may be adjusted according to the distance between the current sample and the reference sample to improve the accuracy of intra prediction.
- the accuracy of intra prediction is improved, the compression ratio and the image quality are increased as the prediction error, which is a difference between the original image and the predicted image, decreases.
- FIG. 1A is a block diagram of an image encoding apparatus 100 based on coding units having a tree structure, according to an embodiment of the present invention.
- FIG. 1B is a block diagram of a video decoding apparatus 150 based on coding units having a tree structure, according to an embodiment.
- FIG. 2A is a block diagram of an image encoding apparatus 200 according to an embodiment of the present invention.
- FIG. 2B illustrates a block diagram of a decoding apparatus 250 according to an embodiment.
- FIG. 3 illustrates a process of determining at least one coding unit by dividing a current coding unit according to an embodiment.
- FIG. 4 is a diagram illustrating a process of dividing a coding unit having a non-square shape and determining at least one coding unit according to an embodiment.
- FIG. 5 illustrates a process of splitting a coding unit based on at least one of block shape information and split shape information, according to an embodiment.
- FIG. 6 illustrates a method of determining a predetermined coding unit among odd number of coding units according to an embodiment.
- FIG. 7 illustrates an order in which a plurality of coding units are processed when a current coding unit is divided and a plurality of coding units are determined according to an embodiment.
- FIG. 8 illustrates a process of determining that a current coding unit is divided into an odd number of coding units when the coding units cannot be processed in a predetermined order, according to an embodiment.
- FIG. 9 is a diagram illustrating a process of determining at least one coding unit by dividing a first coding unit according to an embodiment.
- FIG. 10 illustrates that a form in which a second coding unit may be split is limited when the second coding unit having a non-square shape determined by splitting the first coding unit satisfies a predetermined condition according to an embodiment. .
- FIG. 11 illustrates a process of splitting a coding unit having a square shape when split information cannot be divided into four square coding units according to an embodiment.
- FIG. 12 illustrates that a processing order between a plurality of coding units may vary according to a splitting process of coding units, according to an embodiment.
- FIG. 13 illustrates a process of determining a depth of a coding unit as a shape and a size of a coding unit change when a coding unit is recursively divided to determine a plurality of coding units according to an embodiment.
- FIG. 14 illustrates a depth and a part index (PID) for classifying coding units, which may be determined according to the shape and size of coding units, according to an embodiment.
- PID depth and a part index
- FIG. 15 illustrates that a plurality of coding units are determined according to a plurality of predetermined data units included in a picture according to an embodiment.
- FIG. 16 illustrates a processing block serving as a reference for determining a determination order of reference coding units included in a picture, according to an exemplary embodiment.
- FIG. 16 illustrates a video decoding apparatus 1600 according to an embodiment of determining an encoding order of blocks.
- FIG. 17 illustrates an image prediction apparatus 1700 which performs intra prediction of blocks included in an image.
- 18A and 18B show a method of determining the one-dimensional adjacent sample arrangement of the adjacent sample acquirer.
- 19A and 19B illustrate a method of determining a reference sample according to a position of a current sample and an intra mode of a current block.
- FIG. 20 illustrates a method of adjusting a sample value of a reference sample according to the reference distance and the adjacent sample representative value.
- 21A and 21B show a method of adjusting a reference sample using a smoothing filter according to a reference distance.
- 22 is a flowchart illustrating a method of predicting a current sample by adjusting a reference sample of the current sample according to a reference distance of the current sample.
- part refers to a hardware component, such as software, FPGA or ASIC, and “part” plays certain roles. However, “part” is not meant to be limited to software or hardware.
- the “unit” may be configured to be in an addressable storage medium and may be configured to play one or more processors.
- a “part” refers to components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, Subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays and variables.
- the functionality provided within the components and “parts” may be combined into a smaller number of components and “parts” or further separated into additional components and “parts”.
- “Current block” means one of coding units, prediction units, and transformation units that are currently encoded or decoded.
- a “lower block” means a data unit divided from a “current block”.
- “upper block” means a data unit including the "current block”.
- sample is data to be assigned to the sampling position of the video image to be processed.
- pixel values and transform coefficients on a transform region may be samples in an image of a spatial domain.
- a unit including the at least one sample may be defined as a block.
- FIG. 1A is a block diagram of an image encoding apparatus 100 based on coding units having a tree structure, according to an embodiment of the present invention.
- the image encoding apparatus 100 includes an encoder 110 and an output unit 120.
- the encoder 110 may encode an image according to a plurality of encoding methods.
- the encoder 110 may select the most efficient encoding method by comparing encoding results of a plurality of encoding methods. Which encoding method is most efficient may be determined according to Rate-Distortion Optimization. For example, when the encoding method A and the encoding method B are incompatible with each other, the encoding unit 110 may encode an image according to a more efficient encoding method among the encoding method A and the encoding method B according to the rate-distortion optimization.
- the encoder 110 divides a picture or a slice included in the picture into a plurality of maximum coding units according to the size of the maximum coding unit.
- the maximum coding unit is a data unit having a size of 32x32, 64x64, 128x128, 256x256, and the like, and may be a square data unit having a square of two horizontal and vertical sizes.
- the encoder 110 may provide the output unit 120 with maximum coding unit size information indicating the size of the maximum coding unit.
- the output unit 120 may include the maximum coding unit size information in the bitstream.
- the encoder 110 determines the coding unit by dividing the maximum coding unit. Coding units may be determined to have a maximum size and depth. The depth may be defined as the number of times a coding unit is spatially divided from the largest coding unit. Each time the depth is increased by 1, the coding unit is divided into two or more coding units. Therefore, as the depth increases, the size of the coding unit for each depth decreases. Whether the coding unit is split or not is determined depending on whether the coding unit is efficient by rate-distortion optimization. In addition, split information indicating whether a coding unit is split may be generated. The partitioning information may be expressed in the form of a flag.
- Coding units may be divided in various ways. For example, a square coding unit may be divided into four square coding units each having a half width and a height. The square coding unit may be divided into two rectangular coding units having a half width. Also, a square coding unit may be divided into two rectangular coding units having a height of half. The coding unit of the square may be divided into three coding units by dividing the width or height into 1: 2: 1.
- a rectangular coding unit having a width twice the height may be divided into two square coding units.
- a coding unit of a rectangle having a width twice the height may be split into coding units of a rectangle having two widths four times the height.
- a rectangular coding unit having a width twice the height may be divided into two rectangular coding units and one square coding unit by dividing the width by 1: 2: 1.
- a rectangular coding unit having a height twice the width may be divided into two square coding units.
- a rectangular coding unit having a height twice the width may be divided into a rectangular coding unit having two heights four times the width.
- a rectangular coding unit having a height twice the width may be divided into two rectangular coding units and one square coding unit by dividing the height into 1: 2: 1.
- information on a division method that may be used for a coding unit among the division methods available in the image encoding apparatus 100 may be determined for each picture. Thus, it may be determined that only specific segmentation methods are used per picture. If the image encoding apparatus 100 uses only one division method, information on a division method that may be used for the coding unit is not separately determined.
- split shape information indicating a splitting method of the coding unit may be generated. If there is only one division method that can be used in a picture belonging to a coding unit company, division type information may not be generated. If the division method is adaptively determined based on the encoding information around the coding unit, the division type information may not be generated.
- the maximum coding unit may be split up to the minimum coding unit according to the minimum coding unit size information.
- the depth of the largest coding unit may be the highest depth, and the minimum coding unit may be defined as the lowest depth. Therefore, the coding unit of the higher depth may include coding units of the plurality of lower depths.
- the maximum coding unit may include coding units divided by depths. Since the maximum coding unit is divided according to depths, image data of a spatial domain included in the maximum coding unit may be hierarchically classified according to depths.
- a maximum depth or a minimum size of a coding unit that limits the maximum number of times that the maximum coding unit may be hierarchically divided may be preset.
- the encoder 110 compares the coding efficiency when the coding unit is hierarchically divided from the coding efficiency when the coding unit is not divided. The encoder 110 determines whether to split the coding unit according to the comparison result. If it is determined that the division of the coding unit is more efficient, the encoder 110 hierarchically divides the coding unit. If it is determined that it is efficient not to divide the coding unit according to the comparison result, the coding unit is not divided. Whether to split the coding unit may be determined independently of whether to split another adjacent coding unit.
- whether to split the coding unit may be determined from a coding unit having a large depth in the encoding process. For example, the coding efficiency of the coding unit of the maximum depth and the coding unit smaller by 1 than the maximum depth are compared, so that each of the regions of the maximum coding unit includes any of the coding units of the maximum depth and the coding units smaller than the maximum depth by 1. It is determined whether the encoding is more efficient. According to the determination result, it is determined whether or not to split the coding unit smaller than the maximum depth by 1 for each region of the maximum coding unit.
- Whether to split the coding unit may be determined from a coding unit having a small depth in the encoding process. For example, the coding efficiency of the largest coding unit and a coding unit having a depth of one larger than the maximum coding unit is compared, so that any one of the largest coding unit and the coding units having a depth of one larger than the maximum code unit is more efficiently encoded. Is determined. If the coding efficiency of the maximum coding unit is better, the maximum coding unit is not divided. If the coding efficiency of coding units having a depth of 1 is greater than that of the maximum coding unit, the maximum coding unit is split, and the same comparison process is repeated for the split coding unit.
- an algorithm for obtaining a hierarchical tree structure of the largest coding unit may be designed in various ways in consideration of coding efficiency and calculation amount.
- the encoder 110 determines the most efficient prediction and transformation method for the coding unit in order to determine the efficiency of the coding unit for each depth.
- the coding unit may be divided into predetermined data units to determine the most efficient prediction and transformation method.
- the data unit may have various forms according to the division method of the coding unit.
- a splitting method of coding units for determining a data unit may be defined as a partition mode. For example, when a coding unit of size 2Nx2N (where N is a positive integer) is not divided, the size of the prediction unit included in the coding unit is 2Nx2N. When the coding unit having the size 2Nx2N is split, the size of the prediction unit included in the coding unit may be 2NxN, Nx2N, NxN, etc.
- Partition mode is not only the symmetric data units in which the height or width of the coding unit is divided by the symmetric ratio, but also the data units divided by the asymmetric ratio such as 1: n or n: 1, diagonal It is possible to generate data units divided into data units, data units divided into other geometric shapes, and data units of arbitrary shape.
- the coding unit may perform prediction and transformation based on the data unit included in the coding unit.
- a data unit for prediction and a data unit for conversion may be separately determined.
- the data unit for prediction may be defined as a prediction unit
- the data unit for transformation may be defined as a transformation unit.
- the partition mode applied to the prediction unit and the partition mode applied to the transformation unit may be different from each other.
- the prediction of the prediction unit and the transformation of the transformation unit in the coding unit may be performed in parallel and independently.
- the coding unit may be divided into one or more prediction units in order to determine an efficient prediction method.
- a coding unit may be divided into one or more transformation units in order to determine an efficient transformation method. Splitting of the prediction unit and splitting of the transform unit may be performed independently. However, when the reconstructed sample inside the coding unit is used for intra prediction, a dependent relationship is formed between the prediction units or the transformation units included in the coding unit, and thus the division of the prediction unit and the transformation unit may affect each other.
- the prediction unit included in the coding unit may be predicted by intra prediction or inter prediction.
- Intra prediction is a method of predicting samples of a prediction unit using reference samples around the prediction unit.
- Inter prediction is a method of predicting samples of a prediction unit by obtaining a reference sample from a reference picture referenced by the current picture.
- the encoder 110 may select the most efficient intra prediction method by applying a plurality of intra prediction methods to the prediction unit for intra prediction.
- Intra prediction methods include a directional mode such as a DC mode, a planar mode, a vertical mode, and a horizontal mode.
- Intra prediction may be performed for each prediction unit when reconstructed samples around the coding unit are used as reference samples.
- the prediction order of the prediction unit may depend on the conversion order of the transform unit. Therefore, when a reconstructed sample inside a coding unit is used as a reference sample, only an intra prediction method for transform units corresponding to the prediction unit is determined for the prediction unit, and substantial intra prediction may be performed for each transform unit.
- the encoder 110 may select the most efficient inter prediction method by determining an optimal motion vector and a reference picture.
- the encoder 110 may determine a plurality of motion vector candidates from neighboring coding units spatially and temporally from the current coding unit for inter prediction, and determine the most efficient motion vector among them as a motion vector.
- a plurality of reference picture candidates may be determined from spatially and temporally neighboring coding units from the current coding unit, and among them, the most efficient reference picture may be determined.
- the reference picture may be determined from among reference picture lists predetermined for the current picture.
- the most efficient motion vector among a plurality of motion vector candidates may be determined as a predictive motion vector, and the motion vector may be determined by correcting the predicted motion vector.
- Inter prediction may be performed in parallel for each prediction unit in the coding unit.
- the encoder 110 may reconstruct a coding unit by obtaining only information representing a motion vector and a reference picture according to a skip mode.
- a skip mode all encoding information including the residual signal is omitted except for information representing a motion vector and a reference picture. Since the residual signal is omitted, the skip mode can be used when the prediction accuracy is very high.
- the partition mode used may be limited according to the prediction method for the prediction unit. For example, only the partition mode for prediction units of 2Nx2N and NxN sizes is applied to intra prediction, while the partition mode for prediction units of 2Nx2N, 2NxN, Nx2N, and NxN sizes may be applied to inter prediction. In addition, only a partition mode for a prediction unit having a size of 2N ⁇ 2N may be applied to a skip mode of inter prediction.
- the partition mode allowed for each prediction method in the image encoding apparatus 100 may be changed according to encoding efficiency.
- the image encoding apparatus 100 may perform transformation based on a coding unit or a transformation unit included in the coding unit.
- the image encoding apparatus 100 may convert residual data, which is a difference value between an original value and a prediction value, of pixels included in a coding unit, through a predetermined process.
- the image encoding apparatus 100 may perform lossy compression on the residual data through quantization and DCT / DST conversion.
- the image encoding apparatus 100 may perform lossless compression on the residual data without quantization.
- the image encoding apparatus 100 may determine a transformation unit that is most efficient for quantization and transformation. In a manner similar to the coding unit according to the tree structure, the transformation unit in the coding unit is also recursively divided into smaller transformation units, and the residual data of the coding unit is partitioned according to the transformation unit according to the tree structure according to the transformation depth. Can be.
- the image encoding apparatus 100 may generate transform split information about the split of the coding unit and the transform unit according to the determined tree structure of the transform unit.
- the image encoding apparatus 100 may set a transformation depth indicating the number of divisions until the height and width of the coding unit are divided to reach the transformation unit. For example, if the size of the transform unit of the current coding unit of size 2Nx2N is 2Nx2N, the transform depth is 0, the transform depth 1 if the size of the transform unit is NxN, and the transform depth 2 if the size of the transform unit is N / 2xN / 2. Can be. That is, a transformation unit having a tree structure may be set according to the transformation depth.
- the encoder 110 determines the most efficient prediction method for the current prediction unit among the plurality of intra prediction methods and the inter prediction methods.
- the encoder 110 determines a prediction unit determination method according to the coding efficiency according to the prediction result.
- the encoder 110 determines a transform unit determination method according to the encoding efficiency according to the transform result.
- the coding efficiency of the coding unit is finally determined according to the most efficient prediction unit and the method of determining the transformation unit.
- the encoder 110 determines the hierarchical structure of the maximum coding unit according to the coding efficiency of the coding unit for each depth.
- the encoder 110 may measure a coding efficiency of coding units according to depths, prediction efficiency of prediction methods, and the like using a Lagrangian Multiplier-based rate-distortion optimization technique.
- the encoder 110 may generate split information indicating whether to split the coding units according to depths according to the determined hierarchical structure of the largest coding unit.
- the encoder 110 may generate partition mode information for determining a prediction unit and transform unit split information for determining a transform unit, for the split coding unit.
- the encoding unit 110 may generate split type information indicating the division method together with the division information.
- the encoder 110 may generate information about a prediction method and a transformation method used in the prediction unit and the transformation unit.
- the outputter 120 may output the information generated by the encoder 110 in the form of a bitstream according to the hierarchical structure of the largest coding unit.
- a method of determining a coding unit, a prediction unit, and a transformation unit according to a tree structure of a maximum coding unit according to an embodiment will be described later in detail with reference to FIGS. 3 to 12.
- FIG. 1B is a block diagram of an image decoding apparatus 150 based on coding units having a tree structure, according to an exemplary embodiment.
- the image decoding apparatus 150 includes a receiver 160 and a decoder 170.
- the receiver 160 receives and parses a bitstream of an encoded video.
- the decoder 170 extracts information necessary for decoding for each largest coding unit from the parsed bitstream.
- the decoder 170 may extract information about a maximum size of a coding unit of the current picture from a header, a sequence parameter set, or a picture parameter set for the current picture.
- the decoder 170 extracts final depth and split information of the coding units having a tree structure for each maximum coding unit from the parsed bitstream.
- the decoder 170 may determine a tree structure of the maximum coding unit by dividing the maximum coding unit according to the extracted final depth and the split information.
- the split information extracted by the decoder 170 is split information about a tree structure determined by the video encoding apparatus 100 to generate a minimum encoding error. Therefore, the image decoding apparatus 150 may reconstruct the image by decoding the data according to an encoding method that generates a minimum encoding error.
- the decoder 170 may extract split information about a data unit such as a prediction unit and a transformation unit included in the coding unit. For example, the decoder 170 may extract information about the most efficient partition mode for the prediction unit. In addition, the decoder 170 may extract transform partition information on a tree structure that is most efficient in a transform unit.
- the decoder 170 may obtain information about the most efficient prediction method with respect to the prediction units split from the coding unit. In addition, the decoder 170 may obtain information about a most efficient transformation method for the transformation units split from the coding unit.
- the decoder 170 extracts information from the bitstream according to a method of configuring the bitstream in the output unit 120 of the image encoding apparatus 100.
- the decoder 170 may divide the largest coding unit into coding units having the most efficient tree structure based on the split information.
- the decoder 170 may divide the coding unit into prediction units according to the information about the partition mode.
- the decoder 170 may divide a coding unit into transformation units according to the transformation division information.
- the decoder 170 may predict the prediction unit according to the information on the prediction method.
- the decoder 170 may inversely quantize and inversely transform residual data corresponding to a difference between an original value and a prediction value of a pixel according to information on a method of transforming a transform unit.
- the decoder 170 may reconstruct the pixels of the coding unit according to the prediction result of the prediction unit and the transformation result of the transformation unit.
- FIG. 2A is a block diagram of an image encoder 200 based on coding units, according to various embodiments.
- the image encoder 200 includes operations performed by the encoder 110 of the video encoding apparatus 100 to encode image data. That is, the intra prediction unit 204 performs intra prediction on the coding unit of the intra mode among the current frames 202, and the inter prediction unit 206 performs the current frame 202 and the reference frame 226 of the inter mode. Inter prediction is performed.
- the prediction error data determined according to the prediction by the intra predictor 204 or the inter predictor 206 is output as a quantized transform coefficient through the transform unit 210 and the quantization unit 212.
- the quantized transform coefficients are restored to the prediction error data of the spatial domain through the inverse quantizer 218 and the inverse transformer 220, and the decoded prediction error data of the reconstructed spatial domain is deblocked 222 and the offset adjuster 224.
- the reference frame 226 is generated by combining the post-processed prediction error data with the prediction data of the intra prediction unit 204 or the inter prediction unit 206.
- the quantized transform coefficients may be output to the bitstream 216 via the entropy encoder 214.
- the inverse transform unit 220, the deblocking unit 222, and the offset adjuster 224 are performed on each of coding units having a tree structure of an image.
- the intra prediction unit 204 and the inter prediction unit 206 determine a partition and a prediction mode of each coding unit among coding units having a tree structure in consideration of the maximum size and the maximum depth of the current maximum coding unit.
- the transformer 210 determines a size of a transform unit in each coding unit among coding units having a tree structure.
- 2B is a block diagram of an image decoder 250 based on coding units, according to various embodiments.
- the bitstream 252 is parsed through the parser 254 to encode encoded image data and encoding information necessary for decoding.
- the encoded image data is output as inverse quantized data through the entropy decoding unit 256 and the inverse quantization unit 258, and the prediction error data of the spatial domain is restored through the inverse transformation unit 260.
- the intra prediction unit 262 performs intra prediction on the coding unit of the intra mode, and the inter prediction unit 264 uses the reference frame 270 to apply to the coding unit of the inter mode. Perform inter prediction on the
- the predicted data predicted by the intra predictor 262 and the inter predictor 264 are post-processed through the deblocking unit 266 and the offset compensator 268.
- the reconstructed frame 272 may be generated by combining the post-processed prediction data and the prediction error data.
- step-by-step operations after the parser 254 of the image decoder 250 may be performed.
- the deblocking unit 266 and the offset compensator 268 are performed on each of coding units having a tree structure of an image.
- the intra predictor 262 and the inter predictor 264 determine a partition and a prediction mode for each coding unit having a tree structure, and the inverse transformer 260 determines the size of a transform unit for each coding unit.
- FIG 3 illustrates a process of determining, by the image decoding apparatus 150, at least one coding unit by dividing a current coding unit according to an embodiment.
- the image decoding apparatus 150 may determine a shape of a coding unit by using block shape information, and may determine which type of coding unit is divided by using split shape information. That is, the method of dividing the coding unit indicated by the segmentation form information may be determined according to which block form the block form information used by the image decoding apparatus 150 represents.
- the image decoding apparatus 150 may use block shape information indicating that the current coding unit is square. For example, the image decoding apparatus 150 may determine whether to split a square coding unit, to split vertically, to split horizontally, or to split into four coding units according to the split type information. Referring to FIG. 3, when the block shape information of the current coding unit 300 indicates a square shape, the decoder 170 may have the same size as the current coding unit 300 according to the split shape information indicating that the block shape information is not divided. The splitting unit 210a may not split the coding unit 210a, or may be determined based on split type information indicating a predetermined division method.
- the image decoding apparatus 150 determines two coding units 310b that split the current coding unit 300 in the vertical direction based on split type information indicating that the image is split in the vertical direction. Can be.
- the image decoding apparatus 150 may determine two coding units 310c that divide the current coding unit 300 in the horizontal direction, based on the split type information indicating the split in the horizontal direction.
- the image decoding apparatus 150 may determine four coding units 310d that divide the current coding unit 300 in the vertical direction and the horizontal direction based on the split type information indicating that the image decoding apparatus 150 is split in the vertical direction and the horizontal direction.
- the divided form in which the square coding unit may be divided should not be limited to the above-described form and may include various forms represented by the divided form information. Certain division forms in which a square coding unit is divided will be described in detail with reference to various embodiments below.
- FIG. 4 illustrates a process of determining, by the image decoding apparatus 150, at least one coding unit by dividing a coding unit having a non-square shape according to an embodiment.
- the image decoding apparatus 150 may use block shape information indicating that a current coding unit is a non-square shape.
- the image decoding apparatus 150 may determine whether to divide the current coding unit of the non-square according to the segmentation type information or to split it by a predetermined method. Referring to FIG. 4, when the block shape information of the current coding unit 400 or 450 indicates a non-square shape, the image decoding apparatus 150 may not divide the current coding unit 400 according to the split shape information indicating that the shape is not divided.
- coding units 410a, 420b, 430a, 430b, 430c, 470a which do not divide coding units 410 or 460 having the same size as 450, or are divided based on division type information indicating a predetermined division method.
- 470b, 480a, 480b, and 480c can be determined.
- a predetermined division method in which a non-square coding unit is divided will be described in detail with reference to various embodiments below.
- the image decoding apparatus 150 may determine a shape in which a coding unit is divided using split shape information.
- the split shape information may include the number of at least one coding unit generated by splitting the coding unit. Can be represented.
- the image decoding apparatus 150 may determine the current coding unit 400 or 450 based on the split shape information. By splitting, two coding units 420a, 420b, or 470a, 470b included in the current coding unit may be determined.
- the image decoding apparatus 150 when the image decoding apparatus 150 divides the current coding unit 400 or 450 having the non-square shape based on the split shape information, the image coding apparatus 150 of the non-square current coding unit 400 or 450 has the same shape.
- the current coding unit may be split in consideration of the position of the long side. For example, the image decoding apparatus 150 divides the current coding unit 400 or 450 in a direction of dividing a long side of the current coding unit 400 or 450 in consideration of the shape of the current coding unit 400 or 450. To determine a plurality of coding units.
- the image decoding apparatus 150 may determine an odd number of coding units included in the current coding unit 400 or 450. For example, when the split type information indicates that the current coding unit 400 or 450 is divided into three coding units, the image decoding apparatus 150 may divide the current coding unit 400 or 450 into three coding units 430a. , 430b, 430c, 480a, 480b, and 480c. According to an embodiment, the image decoding apparatus 150 may determine an odd number of coding units included in the current coding unit 400 or 450, and not all sizes of the determined coding units may be the same.
- the size of a predetermined coding unit 430b or 480b among the determined odd coding units 430a, 430b, 430c, 480a, 480b, and 480c is different from other coding units 430a, 430c, 480a, and 480c. May have That is, the coding unit that may be determined by dividing the current coding unit 400 or 450 may have a plurality of types of sizes.
- the image decoding apparatus 150 may determine an odd number of coding units included in the current coding unit 400 or 450.
- the image decoding apparatus 150 may set a predetermined limit on at least one coding unit among odd-numbered coding units generated by dividing.
- the image decoding apparatus 150 may include a coding unit positioned at the center of three coding units 430a, 430b, 430c, 480a, 480b, and 480c generated by dividing a current coding unit 400 or 450.
- the decoding process for 430b and 480b may be different from other coding units 430a, 430c, 480a and 480c.
- the image decoding apparatus 150 restricts the coding units 430b and 480b located in the center from being no longer divided, or only by a predetermined number of times. You can limit it to split.
- FIG. 5 illustrates a process of splitting a coding unit by the image decoding apparatus 150 based on at least one of block shape information and split shape information, according to an exemplary embodiment.
- the image decoding apparatus 150 may determine to divide or not divide the first coding unit 500 having a square shape into coding units based on at least one of block shape information and split shape information.
- the image decoding apparatus 150 splits the first coding unit 500 in the horizontal direction to divide the second coding unit. 510 may be determined.
- the first coding unit, the second coding unit, and the third coding unit used according to an embodiment are terms used to understand a before and after relationship between the coding units.
- the first coding unit is split, the second coding unit may be determined.
- the third coding unit may be determined.
- the relationship between the first coding unit, the second coding unit, and the third coding unit used is based on the above-described feature.
- the image decoding apparatus 150 may determine to divide or not split the determined second coding unit 510 into coding units based on at least one of block shape information and split shape information. Referring to FIG. 5, the image decoding apparatus 150 may determine a second coding unit 510 having a non-square shape determined by dividing the first coding unit 500 based on at least one of block shape information and split shape information. It may be split into at least one third coding unit 520a, 520b, 520c, 520d, or the like, or may not split the second coding unit 510.
- the image decoding apparatus 150 may obtain at least one of the block shape information and the split shape information, and the image decoding device 150 may determine the first coding unit 500 based on at least one of the obtained block shape information and the split shape information.
- the unit 500 may be divided according to the divided manner. According to an embodiment, when the first coding unit 500 is divided into the second coding unit 510 based on at least one of the block shape information and the split shape information for the first coding unit 500, the second coding unit 500 may be divided into the second coding unit 500.
- the coding unit 510 may also be divided into third coding units (eg, 520a, 520b, 520c, 520d, etc.) based on at least one of block shape information and split shape information of the second coding unit 510. have. That is, the coding unit may be recursively divided based on at least one of the partition shape information and the block shape information associated with each coding unit. A method that can be used for recursive division of coding units will be described later through various embodiments.
- third coding units eg, 520a, 520b, 520c, 520d, etc.
- the image decoding apparatus 150 divides each of the third coding units 520a, 520b, 520c, 520d, etc. into coding units based on at least one of block shape information and split shape information, or performs second encoding. It may be determined that the unit 510 is not divided.
- the image decoding apparatus 150 may split the second coding unit 510 having a non-square shape into an odd number of third coding units 520b, 520c, and 520d.
- the image decoding apparatus 150 may place a predetermined limit on a predetermined third coding unit among the odd number of third coding units 520b, 520c, and 520d.
- the image decoding apparatus 150 should be limited to the number of coding units 520c positioned in the middle of the odd number of third coding units 520b, 520c, and 520d, which are no longer divided or set by the number of times that can be set. It can be limited to.
- the image decoding apparatus 150 may include a coding unit positioned at the center among odd-numbered third coding units 520b, 520c, and 520d included in the second coding unit 510 having a non-square shape.
- 520c is no longer divided, or is limited to being divided into a predetermined division form (for example, divided into only four coding units or divided into a form corresponding to the divided form of the second coding unit 510), or predetermined.
- the above limitation on the coding unit 520c located in the center is merely a mere embodiment and thus should not be construed as being limited to the above-described embodiments, and the coding unit 520c located in the center may be different from other coding units 520b and 520d. ), It should be interpreted as including various restrictions that can be decoded.
- FIG. 6 illustrates a method for the image decoding apparatus 150 to determine a coding unit of a predetermined position among odd-numbered coding units according to an embodiment.
- the image decoding apparatus 150 may use information indicating the position of each of the odd coding units to determine a coding unit located in the middle of the odd coding units. Referring to FIG. 6, the image decoding apparatus 150 may determine an odd number of coding units 620a, 620b, and 620c by dividing the current coding unit 600. The image decoding apparatus 150 may determine the central coding unit 620b by using information about the positions of the odd number of coding units 620a, 620b, and 620c.
- the image decoding apparatus 150 determines the positions of the coding units 620a, 620b, and 620c based on the information indicating the positions of the predetermined samples included in the coding units 620a, 620b, and 620c.
- the coding unit 620b positioned at may be determined.
- the image decoding apparatus 150 may determine the coding units 620a, 620b, and 620c based on the information indicating the positions of the samples 630a, 630b, and 630c in the upper left of the coding units 620a, 620b, and 620c. By determining the position, the coding unit 620b positioned in the center may be determined.
- the information indicating the positions of the upper left samples 630a, 630b, and 630c included in the coding units 620a, 620b, and 620c may be located in the pictures of the coding units 620a, 620b, and 620c, respectively. Or it may include information about the coordinates. According to an embodiment, the information indicating the positions of the upper left samples 630a, 630b, and 630c included in the coding units 620a, 620b, and 620c may be included in the current coding unit 600.
- 620c may include information indicating width or height, and the width or height may correspond to information indicating a difference between coordinates in a picture of the coding units 620a, 620b, and 620c. That is, the image decoding apparatus 150 may directly use information about the position or coordinates in the pictures of the coding units 620a, 620b, and 620c or may obtain information about the width or height of the coding unit corresponding to the difference between the coordinates. By using this, the coding unit 620b positioned in the center can be determined.
- the information indicating the position of the sample 630a at the upper left of the upper coding unit 620a may indicate (xa, ya) coordinates, and the sample 630b at the upper left of the middle coding unit 620b.
- the information indicating the position of) may indicate the (xb, yb) coordinates, and the information indicating the position of the sample 630c on the upper left of the lower coding unit 620c may indicate the (xc, yc) coordinates.
- the image decoding apparatus 150 may determine the center coding unit 620b using the coordinates of the samples 630a, 630b, and 630c in the upper left included in the coding units 620a, 620b, and 620c, respectively.
- the coordinates indicating the positions of the samples 630a, 630b, and 630c in the upper left corner may indicate coordinates representing the absolute positions in the picture, and further, the positions of the samples 630a in the upper left corner of the upper coding unit 620a.
- the (dxb, dyb) coordinate which is the information indicating the relative position of the upper left sample 630b of the middle coding unit 620b, and the relative position of the upper left sample 630c of the lower coding unit 620c.
- Information (dxc, dyc) coordinates can also be used.
- the method of determining the coding unit of a predetermined position by using the coordinates of the sample as information indicating the position of the sample included in the coding unit should not be interpreted to be limited to the above-described method, and various arithmetic operations that can use the coordinates of the sample are available. It should be interpreted in a way.
- the image decoding apparatus 150 may divide the current coding unit 600 into a plurality of coding units 620a, 620b, and 620c, and may determine a predetermined reference among the coding units 620a, 620b, and 620c. According to the coding unit can be selected. For example, the image decoding apparatus 150 may select coding units 620b having different sizes from among coding units 620a, 620b, and 620c.
- the image decoding apparatus 150 may include (xa, ya) coordinates, which are information indicating the position of the sample 630a on the upper left side of the upper coding unit 620a, and the sample on the upper left side of the center coding unit 620b.
- the coding unit 620a using the (xb, yb) coordinates indicating the position of 630b and the (xc, yc) coordinates indicating the position of the sample 630c on the upper left side of the lower coding unit 620c.
- 620b, 620c may determine the width or height of each.
- the image decoding apparatus 150 uses (xa, ya), (xb, yb), and (xc, yc) coordinates indicating the positions of the coding units 620a, 620b, and 620c. ) Each size can be determined.
- the image decoding apparatus 150 may determine the width of the upper coding unit 620a as xb-xa and the height as yb-ya. According to an embodiment, the image decoding apparatus 150 may determine the width of the central coding unit 620b as xc-xb and the height as yc-yb. According to an embodiment, the image decoding apparatus 150 may determine the width or height of the lower coding unit using the width or height of the current coding unit, the width and height of the upper coding unit 620a, and the middle coding unit 620b. .
- the image decoding apparatus 150 may determine a coding unit having a different size from other coding units based on the width and the height of the determined coding units 620a, 620b, and 620c. Referring to FIG. 6, the image decoding apparatus 150 may determine a coding unit 620b as a coding unit having a predetermined position while having a size different from that of the upper coding unit 620a and the lower coding unit 620c. However, in the above-described process of determining, by the image decoding apparatus 150, a coding unit having a size different from another coding unit, the coding unit at a predetermined position is determined using the size of the coding unit determined based on the sample coordinates. In this regard, various processes of determining a coding unit at a predetermined position by comparing the sizes of coding units determined according to predetermined sample coordinates may be used.
- the position of the sample to be considered for determining the position of the coding unit should not be interpreted as being limited to the upper left side described above, but may be interpreted that information on the position of any sample included in the coding unit may be used.
- the image decoding apparatus 150 may select a coding unit of a predetermined position among odd-numbered coding units determined by dividing the current coding unit in consideration of the shape of the current coding unit. For example, if the current coding unit has a non-square shape having a width greater than the height, the image decoding apparatus 150 may determine the coding unit at a predetermined position in the horizontal direction. That is, the image decoding apparatus 150 may determine one of the coding units having different positions in the horizontal direction and place a restriction on the corresponding coding unit. If the current coding unit has a non-square shape having a height greater than the width, the image decoding apparatus 150 may determine the coding unit at a predetermined position in the vertical direction. That is, the image decoding apparatus 150 may determine one of the coding units having different positions in the vertical direction to limit the corresponding coding unit.
- the image decoding apparatus 150 may use information indicating the positions of each of the even coding units in order to determine the coding unit of the predetermined position among the even coding units.
- the image decoding apparatus 150 may determine an even number of coding units by dividing a current coding unit and determine a coding unit of a predetermined position by using information about the positions of the even coding units.
- a detailed process for this may be a process corresponding to a process of determining a coding unit of a predetermined position (for example, a middle position) among the odd number of coding units described above with reference to FIG. 6.
- a predetermined value for a coding unit of a predetermined position in the splitting process is determined to determine a coding unit of a predetermined position among the plurality of coding units.
- Information is available.
- the image decoding apparatus 150 may determine the block shape information and the split shape stored in the sample included in the middle coding unit in the splitting process in order to determine a coding unit located in the middle among the coding units in which the current coding unit is divided into a plurality. At least one of the information may be used.
- the image decoding apparatus 150 may divide the current coding unit 600 into a plurality of coding units 620a, 620b, and 620c based on at least one of block shape information and split shape information.
- a coding unit 620b positioned in the middle of the plurality of coding units 620a, 620b, and 620c may be determined.
- the image decoding apparatus 150 may determine a coding unit 620b positioned in the center in consideration of a position where at least one of the block shape information and the split shape information is obtained. That is, at least one of the block shape information and the split shape information of the current coding unit 600 may be obtained from a sample 640 located in the center of the current coding unit 600.
- the block shape information and the split shape information may be obtained.
- the coding unit 620b including the sample 640 is a coding unit positioned at the center. You can decide.
- the information used to determine the coding unit located in the middle should not be interpreted as being limited to at least one of the block type information and the split type information, and various types of information may be used in the process of determining the coding unit located in the center. Can be.
- predetermined information for identifying a coding unit of a predetermined position may be obtained from a predetermined sample included in the coding unit to be determined.
- the image decoding apparatus 150 may divide a current coding unit 600 into a plurality of coding units (eg, divided into a plurality of coding units 620a, 620b, and 620c) determined by splitting the current coding unit 600.
- Block shape information obtained from a sample at a predetermined position for example, a sample located in the center of the current coding unit 600
- At least one of the partition type information may be used. .
- the image decoding apparatus 150 may determine a sample of the predetermined position in consideration of the block block form of the current coding unit 600, and the image decoding apparatus 150 may determine that the current coding unit 600 is divided and determined.
- a coding unit 620b including a sample from which predetermined information (for example, at least one of block shape information and split shape information) may be obtained may be determined.
- predetermined information for example, at least one of block shape information and split shape information
- the image decoding apparatus 150 may determine a sample 640 positioned in the center of the current coding unit 600 as a sample from which predetermined information may be obtained.
- the 150 may set a predetermined limit in decoding the coding unit 620b including the sample 640.
- the position of the sample from which the predetermined information can be obtained should not be interpreted as being limited to the above-described position, but may be interpreted as samples of arbitrary positions included in the coding unit 620b to be determined for the purpose of limitation.
- a position of a sample from which predetermined information may be obtained may be determined according to the shape of the current coding unit 600.
- the block shape information may determine whether the shape of the current coding unit is square or non-square, and determine the position of a sample from which the predetermined information may be obtained according to the shape.
- the image decoding apparatus 150 may be positioned on a boundary that divides at least one of the width and the height of the current coding unit in half using at least one of the information on the width and the height on the current coding unit.
- the sample may be determined as a sample from which predetermined information can be obtained.
- the image decoding apparatus 150 may select one of samples adjacent to a boundary that divides the long side of the current coding unit in half. May be determined as a sample from which information may be obtained.
- the image decoding apparatus 150 when the image decoding apparatus 150 divides the current coding unit into a plurality of coding units, at least one of the block shape information and the split shape information may be used to determine a coding unit of a predetermined position among the plurality of coding units. You can use one.
- the image decoding apparatus 150 may obtain at least one of block shape information and split shape information from a sample at a predetermined position included in a coding unit, and the image decoding apparatus 150 may divide the current coding unit.
- the generated plurality of coding units may be divided using at least one of split shape information and block shape information obtained from a sample of a predetermined position included in each of the plurality of coding units.
- the coding unit may be recursively split using at least one of block shape information and split shape information obtained from a sample of a predetermined position included in each coding unit. Since the recursive division process of the coding unit has been described above with reference to FIG. 4, a detailed description thereof will be omitted.
- the image decoding apparatus 150 may determine the at least one coding unit by dividing the current coding unit, and determine the order in which the at least one coding unit is decoded in a predetermined block (for example, the current coding unit). Can be determined according to
- FIG. 7 illustrates an order in which a plurality of coding units are processed when the image decoding apparatus 150 determines a plurality of coding units by dividing a current coding unit.
- the image decoding apparatus 150 determines the second coding units 710a and 710b by dividing the first coding unit 700 in the vertical direction according to the block shape information and the split shape information.
- the second coding unit 750a, 750b, 750c, or 750d is determined by dividing the 700 in the horizontal direction to determine the second coding units 730a and 730b, or by splitting the first coding unit 700 in the vertical and horizontal directions. Can be determined.
- the image decoding apparatus 150 may determine an order such that the second coding units 710a and 710b determined by dividing the first coding unit 700 in the vertical direction are processed in the horizontal direction 710c. .
- the image decoding apparatus 150 may determine the processing order of the second coding units 730a and 730b determined by dividing the first coding unit 700 in the horizontal direction, in the vertical direction 730c.
- the image decoding apparatus 150 processes the coding units for positioning the second coding units 750a, 750b, 750c, and 750d in one row.
- the coding units located in the next row may be determined according to a predetermined order (for example, raster scan order or z scan order 750e).
- the image decoding apparatus 150 may recursively split coding units. Referring to FIG. 7, the image decoding apparatus 150 may determine a plurality of coding units 710a, 710b, 730a, 730b, 750a, 750b, 750c, and 750d by dividing the first coding unit 700. Each of the plurality of determined coding units 710a, 710b, 730a, 730b, 750a, 750b, 750c, and 750d may be recursively divided.
- the method of splitting the plurality of coding units 710a, 710b, 730a, 730b, 750a, 750b, 750c, and 750d may be a method corresponding to the method of splitting the first coding unit 700. Accordingly, the plurality of coding units 710a, 710b, 730a, 730b, 750a, 750b, 750c, and 750d may be independently divided into a plurality of coding units. Referring to FIG. 7, the image decoding apparatus 150 may determine the second coding units 710a and 710b by dividing the first coding unit 700 in the vertical direction, and further, respectively, the second coding units 710a and 710b. It can be decided to split independently or not.
- the image decoding apparatus 150 may divide the second coding unit 710a on the left side into horizontal units to split the second coding unit 710a into third coding units 720a and 720b, and the second coding unit 710b on the right side. ) May not be divided.
- the processing order of coding units may be determined based on a split process of the coding units.
- the processing order of the divided coding units may be determined based on the processing order of the coding units immediately before being split.
- the image decoding apparatus 150 may independently determine the order in which the third coding units 720a and 720b determined by splitting the second coding unit 710a on the left side from the second coding unit 710b on the right side. Since the second coding unit 710a on the left is divided in the horizontal direction to determine the third coding units 720a and 720b, the third coding units 720a and 720b may be processed in the vertical direction 720c.
- the right coding unit 710b may be processed.
- FIG. 8 illustrates a process of determining that a current coding unit is divided into an odd number of coding units when the image decoding apparatus 150 may not process the coding units in a predetermined order, according to an exemplary embodiment.
- the image decoding apparatus 150 may determine that the current coding unit is divided into odd coding units based on the obtained block shape information and the split shape information.
- a first coding unit 800 having a square shape may be divided into second coding units 810a and 810b having a non-square shape, and the second coding units 810a and 810b may be independently formed. It may be divided into three coding units 820a, 820b, 820c, 820d, and 820e.
- the image decoding apparatus 150 may determine a plurality of third coding units 820a and 820b by dividing the left coding unit 810a in the horizontal direction among the second coding units, and may include the right coding unit 810b. ) May be divided into odd third coding units 820c, 820d, and 820e.
- the image decoding apparatus 150 determines whether the third coding units 820a, 820b, 820c, 820d, and 820e may be processed in a predetermined order to determine whether there are oddly divided coding units. You can decide. Referring to FIG. 8, the image decoding apparatus 150 may determine third coding units 820a, 820b, 820c, 820d, and 820e by recursively dividing the first coding unit 800.
- the image decoding apparatus 150 may include a first coding unit 800, a second coding unit 810a, 810b, or a third coding unit 820a, 820b, 820c, based on at least one of block shape information and split shape information.
- a coding unit positioned on the right side of the second coding units 810a and 810b may be divided into odd third coding units 820c, 820d, and 820e.
- the order in which the plurality of coding units included in the first coding unit 800 is processed may be a predetermined order (for example, a z-scan order 830).
- 150 may determine whether the third coding unit 820c, 820d, or 820e determined by splitting the right second coding unit 810b into an odd number satisfies a condition that may be processed according to the predetermined order.
- the image decoding apparatus 150 satisfies a condition that the third coding units 820a, 820b, 820c, 820d, and 820e included in the first coding unit 800 may be processed in a predetermined order. And whether the at least one of the width and the height of the second coding unit 810a, 810b is divided in half according to the boundary of the third coding unit 820a, 820b, 820c, 820d, or 820e.
- the third coding units 820a and 820b which are determined by dividing the height of the left second coding unit 810a in the non-square form in half, satisfy the condition, but the right second coding unit 810b is set to 3.
- the third coding units 820c, 820d, and 820e determined by dividing into two coding units does not divide the width or height of the right second coding unit 810b in half
- the third coding units 820c, 820d, 820e may be determined to not satisfy the condition, and the image decoding apparatus 150 determines that the scan sequence is disconnected in the case of dissatisfaction with the condition, and based on the determination result, the right second coding unit 810b It may be determined to be divided into an odd number of coding units.
- the image decoding apparatus 150 may set a predetermined limit on a coding unit of a predetermined position among the divided coding units. Since the above has been described through the embodiments, a detailed description thereof will be omitted.
- the image decoding apparatus 150 may divide the first coding unit 900 based on at least one of the block shape information and the split shape information acquired through the receiver 160.
- the first coding unit 900 having a square shape may be divided into coding units having four square shapes, or may be divided into a plurality of coding units having a non-square shape.
- the image decoding apparatus 150 may include the first coding unit.
- the image decoding apparatus 150 may form a square first coding unit 900.
- second coding units 910a, 910b, and 910c which are determined by being split in the vertical direction, as odd coding units, or second coding units 920a, 920b, and 920c, which are determined by splitting in the horizontal direction.
- the image decoding apparatus 150 may process the second coding units 910a, 910b, 910c, 920a, 920b, and 920c included in the first coding unit 900 in a predetermined order.
- the condition is whether the at least one of the width and height of the first coding unit 900 is divided in half according to the boundary of the second coding unit (910a, 910b, 910c, 920a, 920b, 920c). It is related to whether or not. Referring to FIG. 9, the boundary between the second coding units 910a, 910b, and 910c, which is determined by dividing the first coding unit 900 having a square shape in the vertical direction, divides the width of the first coding unit 900 in half.
- the first coding unit 900 may be determined to not satisfy a condition that may be processed in a predetermined order. Also, since the boundary between the second coding units 920a, 920b, and 920c, which is determined by dividing the first coding unit 900 having a square shape in the horizontal direction, does not divide the width of the first coding unit 900 in half, The one coding unit 900 may be determined as not satisfying a condition that may be processed in a predetermined order. In case of such a condition dissatisfaction, the image decoding apparatus 150 may determine that the scan order is disconnected, and determine that the first coding unit 900 is divided into odd coding units based on the determination result.
- the image decoding apparatus 150 when the image decoding apparatus 150 is divided into an odd number of coding units, the image decoding apparatus 150 may set a predetermined limit on a coding unit of a predetermined position among the divided coding units. Since the above has been described through the embodiments, a detailed description thereof will be omitted.
- the image decoding apparatus 150 may determine various coding units by dividing the first coding unit.
- the image decoding apparatus 150 may split a first coding unit 900 having a square shape and a first coding unit 930 or 950 having a non-square shape into various coding units. .
- FIG. 10 illustrates that a second coding unit is split when a second coding unit having a non-square shape determined by splitting the first coding unit 1000 is satisfied by the image decoding apparatus 150 according to an embodiment. It shows that the form that can be limited.
- the image decoding apparatus 150 may set the first coding unit 1000 having a square shape into a non-square shape based on at least one of block shape information and segmentation shape information acquired through the receiver 160. It may be determined by dividing into two coding units 1010a, 1010b, 1020a, and 1020b. The second coding units 1010a, 1010b, 1020a, and 1020b may be independently divided. Accordingly, the image decoding apparatus 150 determines whether to split or not split into a plurality of coding units based on at least one of block shape information and split shape information associated with each of the second coding units 1010a, 1010b, 1020a, and 1020b. Can be.
- the image decoding apparatus 150 divides the left second coding unit 1010a having a non-square shape in a horizontal direction by dividing the first coding unit 1000 in a vertical direction to form a third coding unit ( 1012a, 1012b) can be determined.
- the right second coding unit 1010b may have the same horizontal direction as the direction in which the left second coding unit 1010a is divided. It can be limited to not be divided into.
- the left second coding unit 1010a and the right second coding unit 1010b are each horizontally.
- the third coding units 1012a, 1012b, 1014a, and 1014b may be determined.
- the image decoding apparatus 150 divides the first coding unit 1000 into four square second coding units 1030a, 1030b, 1030c, and 1030d based on at least one of the block shape information and the split shape information. This is the same result as the above, which may be inefficient in terms of image decoding.
- the image decoding apparatus 150 divides the second coding unit 1020a or 1020b of the non-square shape, determined by dividing the first coding unit 330 in the horizontal direction, in the vertical direction, and then third coding unit. 1022a, 1022b, 1024a, and 1024b can be determined.
- the image decoding apparatus 150 divides one of the second coding units (for example, the upper second coding unit 1020a) in the vertical direction
- another image coding unit for example, the lower end
- the coding unit 1020b may restrict the upper second coding unit 1020a from being split in the vertical direction in the same direction as the split direction.
- FIG. 11 illustrates a process of splitting a coding unit having a square shape by the image decoding apparatus 150 when the split shape information cannot be divided into four square coding units.
- the image decoding apparatus 150 divides the first coding unit 1100 based on at least one of the block shape information and the split shape information to divide the second coding units 1110a, 1110b, 1120a, 1120b, and the like. You can decide.
- the split type information may include information about various types in which a coding unit may be split, but the information on various types may not include information for splitting into four coding units having a square shape.
- the image decoding apparatus 150 may not divide the first coding unit 1100 having a square shape into four second coding units 1130a, 1130b, 1130c, and 1130d having a square shape.
- the image decoding apparatus 150 may determine second non-square second coding units 1110a, 1110b, 1120a, 1120b, and the like based on the segmentation information.
- the image decoding apparatus 150 may independently split the non-square second coding units 1110a, 1110b, 1120a, 1120b, and the like.
- Each of the second coding units 1110a, 1110b, 1120a, 1120b, and the like may be split in a predetermined order through a recursive method, which is based on at least one of block shape information and split shape information 1100. ) May be a division method corresponding to the division method.
- the image decoding apparatus 150 may determine the third coding units 1112a and 1112b having a square shape by dividing the left second coding unit 1110a in the horizontal direction, and the right second coding unit 1110b may The third coding units 1114a and 1114b having a square shape may be determined by being split in the horizontal direction. Furthermore, the image decoding apparatus 150 may divide the left second coding unit 1110a and the right second coding unit 1110b in the horizontal direction to determine the third coding units 1116a, 1116b, 1116c, and 1116d having a square shape. have. In this case, the coding unit may be determined in the same form as that in which the first coding unit 1100 is divided into four second coding units 1130a, 1130b, 1130c, and 1130d.
- the image decoding apparatus 150 may determine the third coding units 1122a and 1122b having a square shape by dividing the upper second coding unit 1120a in the vertical direction, and the lower second coding unit 1120b. ) May be divided in the vertical direction to determine the third coding units 1124a and 1124b having a square shape. Furthermore, the image decoding apparatus 150 may divide the upper second coding unit 1120a and the lower second coding unit 1120b in the vertical direction to determine the third coding units 1122a, 1122b, 1124a, and 1124b having a square shape. have. In this case, the coding unit may be determined in the same form as that in which the first coding unit 1100 is divided into four second coding units 1130a, 1130b, 1130c, and 1130d.
- FIG. 12 illustrates that a processing order between a plurality of coding units may vary according to a splitting process of coding units, according to an embodiment.
- the image decoding apparatus 150 may divide the first coding unit 1200 based on the block shape information and the split shape information.
- the image decoding apparatus 150 may determine the first coding unit 1200.
- a second coding unit eg, 1210a, 1210b, 1220a, 1220b, 1230a, 1230b, 1230c, 1230d, etc.
- non-square second coding units 1210a, 1210b, 1220a, and 1220b which are determined by dividing the first coding unit 1200 in only the horizontal direction or the vertical direction, respectively, may include block shape information and split shape information for each. It can be divided independently based on.
- the image decoding apparatus 150 divides the second coding units 1210a and 1210b generated by splitting the first coding unit 1200 in the vertical direction in the horizontal direction, respectively, to generate the third coding units 1216a and 1216b, 1216c and 1216d, and the second coding units 1220a and 1220b generated by dividing the first coding unit 1200 in the horizontal direction are divided in the horizontal direction, respectively, and the third coding units 1226a, 1226b and 1226c. 1226d). Since the splitting process of the second coding units 1210a, 1210b, 1220a, and 1220b has been described above with reference to FIG. 10, a detailed description thereof will be omitted.
- the image decoding apparatus 150 may process coding units in a predetermined order. Features of the processing of coding units according to a predetermined order have been described above with reference to FIG. 6, and thus detailed description thereof will be omitted. Referring to FIG. 12, the image decoding apparatus 150 splits a first coding unit 1200 having a square shape to form three square third coding units 1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, and 1226d. ) Can be determined.
- the image decoding apparatus 150 may process a sequence of the third coding units 1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, and 1226d according to a form in which the first coding unit 1200 is divided. You can decide.
- the image decoding apparatus 150 determines the third coding units 1216a, 1216b, 1216c, and 1216d by dividing the second coding units 1210a and 1210b generated by dividing in the vertical direction in the horizontal direction, respectively.
- the image decoding apparatus 150 may first process the third coding units 1216a and 1216b included in the left second coding unit 1210a in the vertical direction, and then include the right second coding unit 1210b.
- the third coding units 1216a, 1216b, 1216c, and 1216d may be processed according to an order 1217 of processing the third coding units 1216c and 1216d in the vertical direction.
- the image decoding apparatus 150 determines the third coding units 1226a, 1226b, 1226c, and 1226d by dividing the second coding units 1220a and 1220b generated by dividing in the horizontal direction in the vertical direction.
- the image decoding apparatus 150 may first process the third coding units 1226a and 1226b included in the upper second coding unit 1220a in the horizontal direction, and then include the lower second coding unit 1220b.
- the third coding units 1226a, 1226b, 1226c, and 1226d may be processed according to an order 1227 of processing the third coding units 1226c and 1226d in the horizontal direction.
- second coding units 1210a, 1210b, 1220a, and 1220b may be divided, respectively, and square third coding units 1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, and 1226d may be determined. have.
- the second coding units 1210a and 1210b that are determined by being split in the vertical direction and the second coding units 1220a and 1220b that are determined by being split in the horizontal direction are divided into different forms, but are determined afterwards.
- 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, and 1226d may result in the first coding unit 1200 being split into coding units having the same shape.
- the image decoding apparatus 150 may recursively divide the coding units through different processes based on at least one of the block shape information and the split shape information, thereby determining the coding units having the same shape. Coding units may be processed in different orders.
- FIG. 13 illustrates a process of determining a depth of a coding unit as a shape and a size of a coding unit change when a coding unit is recursively divided to determine a plurality of coding units according to an embodiment.
- the image decoding apparatus 150 may determine the depth of the coding unit according to a predetermined criterion.
- the predetermined criterion may be the length of the long side of the coding unit.
- the depth of the current coding unit is greater than the depth of the coding unit before the split. It can be determined that the depth is increased by n.
- a coding unit having an increased depth is expressed as a coding unit of a lower depth.
- the image decoding apparatus 150 may have a square shape based on block shape information indicating a square shape (for example, block shape information may indicate '0: SQUARE').
- the first coding unit 1300 may be divided to determine a second coding unit 1302, a third coding unit 1304, or the like of a lower depth.
- the second coding unit 1302 determined by dividing the width and height of the first coding unit 1300 by 1/21 times may have a size of NxN. have.
- the third coding unit 1304 determined by dividing the width and the height of the second coding unit 1302 into half the size may have a size of N / 2 ⁇ N / 2.
- the width and height of the third coding unit 1304 correspond to 1/22 times the first coding unit 1300.
- the depth of the first coding unit 1300 is D
- the depth of the second coding unit 1302 which is 1/21 times the width and the height of the first coding unit 1300 may be D + 1
- the depth of the third coding unit 1304, which is 1/22 times the width and the height of 1300 may be D + 2.
- block shape information indicating a non-square shape (e.g., block shape information indicates that the height is a non-square longer than the width '1: NS_VER' or the width is a non-square longer than the height).
- 2: may represent NS_HOR ')
- the image decoding apparatus 150 divides the first coding unit 1310 or 1320 having a non-square shape to form a second coding unit 1312 or 1322 of a lower depth
- the third coding unit 1314 or 1324 may be determined.
- the image decoding apparatus 150 may determine a second coding unit (eg, 1302, 1312, 1322, etc.) by dividing at least one of a width and a height of the Nx2N size of the first coding unit 1310. That is, the image decoding apparatus 150 may divide the first coding unit 1310 in the horizontal direction to determine a second coding unit 1302 having an NxN size or a second coding unit 1322 having an NxN / 2 size.
- the second coding unit 1312 having the size of N / 2 ⁇ N may be determined by splitting in the horizontal direction and the vertical direction.
- the image decoding apparatus 150 determines a second coding unit (eg, 1302, 1312, 1322, etc.) by dividing at least one of a width and a height of the 2N ⁇ N first coding unit 1320. It may be. That is, the image decoding apparatus 150 may determine the second coding unit 1302 having an NxN size or the second coding unit 1312 having an N / 2xN size by dividing the first coding unit 1320 in the vertical direction.
- the second coding unit 1322 having the size of NxN / 2 may be determined by splitting in the horizontal direction and the vertical direction.
- the image decoding apparatus 150 determines at least one of a width and a height of the NxN-sized second coding unit 1302 to determine a third coding unit (eg, 1304, 1314, 1324, etc.). It may be. That is, the image decoding apparatus 150 determines the third coding unit 1304 having the size of N / 2xN / 2 by dividing the second coding unit 1302 in the vertical direction and the horizontal direction, or the N / 2xN / 2 size The three coding units 1314 or the third coding unit 1324 having a size of N / 2 ⁇ N / 2 may be determined.
- a third coding unit eg, 1304, 1314, 1324, etc.
- the image decoding apparatus 150 divides at least one of the width and the height of the N / 2xN sized second coding unit 1312 to form a third coding unit (eg, 1304, 1314, 1324, etc.). May be determined. That is, the image decoding apparatus 150 divides the second coding unit 1312 in the horizontal direction, so that the third coding unit 1304 having the size of N / 2xN / 2 or the third coding unit 1324 having the size of N / 2xN / 2 is provided. ) May be determined or divided into vertical and horizontal directions to determine a third coding unit 1314 having a size of N / 2 ⁇ N / 2.
- the image decoding apparatus 150 divides at least one of a width and a height of the NxN / 2 sized second coding unit 1314 to form a third coding unit (eg, 1304, 1314, 1324, etc.). May be determined. That is, the image decoding apparatus 150 divides the second coding unit 1312 in the vertical direction to form a third coding unit 1304 having an N / 2 ⁇ N / 2 size or a third coding unit 1314 having an N / 2xN / 2 size. ) May be determined or divided into vertical and horizontal directions to determine a third coding unit 1324 having a size of N / 2 ⁇ N / 2.
- the image decoding apparatus 150 may divide a square coding unit (for example, 1300, 1302, 1304) into a horizontal direction or a vertical direction.
- the first coding unit 1300 having a size of 2Nx2N is split in the vertical direction to determine the first coding unit 1310 having the size of Nx2N, or the first coding unit 1320 having a size of 2NxN is determined by splitting in the horizontal direction.
- the depth of the coding unit determined by splitting the first coding unit 1300, 1302, or 1304 having a size of 2N ⁇ 2N into the horizontal or vertical direction is determined. May be the same as the depth of the first coding unit 1300, 1302, or 1304.
- the width and height of the third coding unit 1314 or 1324 may correspond to 1/2 times of the first coding unit 1310 or 1320.
- the depth of the second coding unit 1312 or 1314 that is 1/2 the width and height of the first coding unit 1310 or 1320 may be D + 1.
- the depth of the third coding unit 1314 or 1324, which is 1/2 the width and the height of the first coding unit 1310 or 1320, may be D + 2.
- FIG. 14 illustrates a depth and a part index (PID) for classifying coding units, which may be determined according to the shape and size of coding units, according to an embodiment.
- PID depth and a part index
- the image decoding apparatus 150 may determine a second coding unit having various shapes by dividing the first coding unit 1400 having a square shape. Referring to FIG. 14, the image decoding apparatus 150 divides the first coding unit 1400 in at least one of the vertical direction and the horizontal direction according to the split type information to form the second coding units 1402a, 1402b, 1404a, 1404b, 1406a, 1406b, 1406c, 1406d). That is, the image decoding apparatus 150 may determine the second coding units 1402a, 1402b, 1404a, 1404b, 1406a, 1406b, 1406c, and 1406d based on the split shape information about the first coding unit 1400.
- the second coding units 1402a, 1402b, 1404a, 1404b, 1406a, 1406b, 1406c, and 1406d which are determined according to split shape information about the first coding unit 1400 having a square shape, have a long side length. Depth can be determined based on this. For example, since the length of one side of the first coding unit 1400 having a square shape and the length of the long side of the second coding units 1402a, 1402b, 1404a and 1404b of a non-square shape are the same, the first coding unit ( 1400 and the non-square second coding units 1402a, 1402b, 1404a, and 1404b may be regarded as D.
- the image decoding apparatus 150 divides the first coding unit 1400 into four square coding units 1406a, 1406b, 1406c, and 1406d based on the split form information, Since the length of one side of the two coding units 1406a, 1406b, 1406c, and 1406d is 1/2 times the length of one side of the first coding unit 1400, the depths of the second coding units 1406a, 1406b, 1406c, and 1406d are the same. May be a depth of D + 1 that is one depth lower than D, which is a depth of the first coding unit 1400.
- the image decoding apparatus 150 divides the first coding unit 1410 having a height greater than the width in a horizontal direction according to the split shape information, thereby providing a plurality of second coding units 1412a, 1412b, 1414a, 1414b, 1414c).
- the image decoding apparatus 150 divides the first coding unit 1420 having a width greater than the height in the vertical direction according to the split shape information, thereby providing a plurality of second coding units 1422a, 1422b, 1424a, 1424b, 1424c).
- the second coding units 1412a, 1412b, 1414a, 1414b, 1416a, 1416b, 1416c, and 1416d that are determined according to split shape information about the first coding unit 1410 or 1420 having a non-square shape may be Depth may be determined based on the length of the long side. For example, since the length of one side of the second coding units 1412a and 1412b having a square shape is 1/2 times the length of one side of the first coding unit 1410 having a non-square shape having a height greater than the width, the square is square.
- the depths of the second coding units 1402a, 1402b, 1404a, and 1404b of the form are D + 1, which is one depth lower than the depth D of the first coding unit 1410 of the non-square form.
- the image decoding apparatus 150 may divide the non-square first coding unit 1410 into odd second coding units 1414a, 1414b, and 1414c based on the split shape information.
- the odd numbered second coding units 1414a, 1414b, and 1414c may include non-square second coding units 1414a and 1414c and square shape second coding units 1414b.
- the length of the long side of the second coding units 1414a and 1414c of the non-square shape and the length of one side of the second coding unit 1414b of the square shape is 1 / time of the length of one side of the first coding unit 1410.
- the depths of the second coding units 1414a, 1414b, and 1414c may be a depth of D + 1 that is one depth lower than the depth D of the first coding unit 1410.
- the image decoding apparatus 150 corresponds to the above-described method of determining depths of coding units related to the first coding unit 1410 and is related to the first coding unit 1420 having a non-square shape having a width greater than the height. Depth of coding units may be determined.
- the image decoding apparatus 150 may determine the size ratio between the coding units.
- the index can be determined based on this. Referring to FIG. 14, a coding unit 1414b positioned at the center of odd-numbered split coding units 1414a, 1414b, and 1414c has the same width as the other coding units 1414a and 1414c but has a different height. It may be twice the height of the fields 1414a, 1414c. That is, in this case, the coding unit 1414b located in the center may include two of the other coding units 1414a and 1414c.
- the coding unit 1414c located in the next order may be 3 having an index increased by 2. That is, there may be a discontinuity in the value of the index.
- the image decoding apparatus 150 may determine whether odd-numbered split coding units are not the same size based on whether there is a discontinuity of an index for distinguishing between the divided coding units.
- the image decoding apparatus 150 may determine whether the image decoding apparatus 150 is divided into a specific division type based on a value of an index for distinguishing a plurality of coding units determined by dividing from the current coding unit. Referring to FIG. 14, the image decoding apparatus 150 determines an even number of coding units 1412a and 1412b by dividing a first coding unit 1410 having a rectangular shape having a height greater than a width, or an odd number of coding units 1414a and 1414b. 1414c). The image decoding apparatus 150 may use an index (PID) indicating each coding unit to distinguish each of the plurality of coding units. According to an embodiment, the PID may be obtained from a sample (eg, an upper left sample) at a predetermined position of each coding unit.
- a sample eg, an upper left sample
- the image decoding apparatus 150 may determine a coding unit of a predetermined position among coding units determined by splitting by using an index for distinguishing coding units. According to an embodiment, when the split type information of the first coding unit 1410 having a height greater than the width is divided into three coding units, the image decoding apparatus 150 may decode the first coding unit 1410. It may be divided into three coding units 1414a, 1414b, and 1414c. The image decoding apparatus 150 may allocate an index for each of three coding units 1414a, 1414b, and 1414c. The image decoding apparatus 150 may compare the indices of the respective coding units to determine the coding unit among the oddly divided coding units.
- the image decoding apparatus 150 encodes a coding unit 1414b having an index corresponding to a center value among the indices based on the indexes of the coding units, and encodes the center position among the coding units determined by splitting the first coding unit 1410. It can be determined as a unit. According to an embodiment, when determining the indexes for distinguishing the divided coding units, the image decoding apparatus 150 may determine the indexes based on the size ratio between the coding units when the coding units are not the same size. . Referring to FIG. 14, the coding unit 1414b generated by dividing the first coding unit 1410 may include the coding units 1414a and 1414c having the same width but different heights as the other coding units 1414a and 1414c.
- the image decoding apparatus 150 may determine that the image decoding apparatus 150 is divided into a plurality of coding units including coding units having different sizes from other coding units. In this case, when the split form information is divided into odd coding units, the image decoding apparatus 150 may have a shape different from a coding unit having a different coding unit (for example, a middle coding unit) at a predetermined position among the odd coding units.
- the current coding unit can be divided by.
- the image decoding apparatus 150 may determine a coding unit having a different size by using an index (PID) for the coding unit.
- PID index
- the above-described index, the size or position of the coding unit of the predetermined position to be determined are specific to explain an embodiment and should not be construed as being limited thereto. Various indexes and positions and sizes of the coding unit may be used. Should be interpreted.
- the image decoding apparatus 150 may use a predetermined data unit at which recursive division of coding units begins.
- FIG. 15 illustrates that a plurality of coding units are determined according to a plurality of predetermined data units included in a picture according to an embodiment.
- the predetermined data unit may be defined as a data unit in which a coding unit starts to be recursively divided using at least one of block shape information and split shape information. That is, it may correspond to the coding unit of the highest depth used in the process of determining a plurality of coding units for dividing the current picture.
- a predetermined data unit will be referred to as a reference data unit.
- the reference data unit may represent a predetermined size and shape.
- the reference coding unit may include samples of M ⁇ N. M and N may be the same as each other, and may be an integer represented by a multiplier of two. That is, the reference data unit may represent a square or non-square shape, and then may be divided into integer coding units.
- the image decoding apparatus 150 may divide the current picture into a plurality of reference data units. According to an embodiment, the image decoding apparatus 150 may divide a plurality of reference data units for dividing a current picture by using split information for each reference data unit. The division process of the reference data unit may correspond to the division process using a quad-tree structure.
- the image decoding apparatus 150 may determine in advance a minimum size that the reference data unit included in the current picture may have. Accordingly, the image decoding apparatus 150 may determine a reference data unit having various sizes having a minimum size or more, and determine at least one coding unit using block shape information and split shape information based on the determined reference data unit. You can decide.
- the image decoding apparatus 150 may use a reference coding unit 1500 having a square shape, or may use a reference coding unit 1502 having a non-square shape.
- the shape and size of the reference coding unit may include various data units (eg, a sequence, a picture, a slice, and a slice segment) that may include at least one reference coding unit. slice segment, maximum coding unit, etc.).
- the receiver 160 of the image decoding apparatus 150 may obtain at least one of information about the shape of the reference coding unit and information about the size of the reference coding unit from the bitstream for each of the various data units. .
- the process of determining at least one coding unit included in the reference coding unit 1500 having a square shape is described above by splitting the current coding unit 300 of FIG. 3, and the reference coding unit 1500 having a non-square shape has been described. Since the process of determining at least one coding unit included in the above is described above through the process of splitting the current coding unit 1200 or 1250 of FIG. 12, a detailed description thereof will be omitted.
- the image decoding apparatus 150 may determine the size and shape of the reference coding unit in order to determine the size and shape of the reference coding unit according to some data unit predetermined based on a predetermined condition.
- a predetermined condition for example, a data unit having a size less than or equal to a slice
- the various data units for example, a sequence, a picture, a slice, a slice segment, a maximum coding unit, etc.
- an index for identifying the size and shape of the reference coding unit may be obtained.
- the image decoding apparatus 150 may determine the size and shape of the reference data unit for each data unit satisfying the predetermined condition by using the index.
- the index may be obtained and used. In this case, at least one of the size and shape of the reference coding unit corresponding to the index indicating the size and shape of the reference coding unit may be predetermined.
- the image decoding apparatus 150 selects at least one of the size and shape of the predetermined reference coding unit according to the index, thereby selecting at least one of the size and shape of the reference coding unit included in the data unit that is the reference for obtaining the index. You can decide.
- the image decoding apparatus 150 may use at least one reference coding unit included in one maximum coding unit. That is, at least one reference coding unit may be included in the maximum coding unit for dividing an image, and the coding unit may be determined through a recursive division process of each reference coding unit. According to an embodiment, at least one of the width and the height of the maximum coding unit may correspond to an integer multiple of at least one of the width and the height of the reference coding unit. According to an embodiment, the size of the reference coding unit may be a size obtained by dividing the maximum coding unit n times according to a quad tree structure. That is, the image decoding apparatus 150 may determine the reference coding unit by dividing the maximum coding unit n times according to the quad tree structure, and at least one of the block shape information and the split shape information according to various embodiments. Can be divided based on.
- FIG. 16 illustrates a processing block serving as a reference for determining a determination order of a reference coding unit included in a picture 1600, according to an exemplary embodiment.
- the image decoding apparatus 150 may determine at least one processing block for dividing a picture.
- the processing block is a data unit including at least one reference coding unit for dividing an image, and the at least one reference coding unit included in the processing block may be determined in a specific order. That is, the determination order of at least one reference coding unit determined in each processing block may correspond to one of various types of order in which the reference coding unit may be determined, and the reference coding unit determination order determined in each processing block. May be different per processing block.
- the order of determination of the reference coding units determined for each processing block is raster scan, Z-scan, N-scan, up-right diagonal scan, and horizontal scan. It may be one of various orders such as a horizontal scan, a vertical scan, etc., but the order that may be determined should not be construed as being limited to the scan orders.
- the image decoding apparatus 150 may determine the size of at least one processing block included in the image by obtaining information about the size of the processing block.
- the image decoding apparatus 150 may determine the size of at least one processing block included in the image by obtaining information about the size of the processing block from the bitstream.
- the size of such a processing block may be a predetermined size of a data unit indicated by the information about the size of the processing block.
- the receiver 160 of the image decoding apparatus 150 may obtain information about a size of a processing block from a bitstream for each specific data unit.
- the information about the size of the processing block may be obtained from the bitstream in data units such as an image, a sequence, a picture, a slice, and a slice segment. That is, the receiver 160 may obtain information about the size of the processing block from the bitstream for each of the various data units, and the image decoding apparatus 150 may divide the picture using at least the information about the size of the acquired processing block.
- the size of one processing block may be determined, and the size of the processing block may be an integer multiple of the reference coding unit.
- the image decoding apparatus 150 may determine the sizes of the processing blocks 1602 and 1612 included in the picture 1600. For example, the image decoding apparatus 150 may determine the size of the processing block based on the information about the size of the processing block obtained from the bitstream. Referring to FIG. 16, the image decoding apparatus 150 may make the horizontal sizes of the processing blocks 1602 and 1612 four times the horizontal size of the reference coding unit and four times the vertical size of the reference coding unit, according to an exemplary embodiment. You can decide. The image decoding apparatus 150 may determine an order in which at least one reference coding unit is determined in at least one processing block.
- the image decoding apparatus 150 may determine each processing block 1602 and 1612 included in the picture 1600 based on the size of the processing block, and include the processing block 1602 and 1612 in the processing block 1602 and 1612.
- a determination order of at least one reference coding unit may be determined.
- the determination of the reference coding unit may include the determination of the size of the reference coding unit.
- the image decoding apparatus 150 may obtain information about a determination order of at least one reference coding unit included in at least one processing block from a bitstream and based on the obtained information about the determination order.
- the order in which at least one reference coding unit is determined may be determined.
- the information about the determination order may be defined in an order or direction in which reference coding units are determined in the processing block. That is, the order in which the reference coding units are determined may be independently determined for each processing block.
- the image decoding apparatus 150 may obtain information on a determination order of a reference coding unit from a bitstream for each specific data unit.
- the receiver 160 may obtain information about a determination order of a reference coding unit from a bitstream for each data unit such as an image, a sequence, a picture, a slice, a slice segment, and a processing block. Since the information about the determination order of the reference coding unit indicates the determination order of the reference coding unit in the processing block, the information about the determination order may be obtained for each specific data unit including an integer number of processing blocks.
- the image decoding apparatus 150 may determine at least one reference coding unit based on the order determined according to the embodiment.
- the receiver 160 may obtain information about a reference coding unit determination order from the bitstream as information related to the processing blocks 1602 and 1612, and the image decoding apparatus 150 may process the processing block ( An order of determining at least one reference coding unit included in 1602 and 1612 may be determined, and at least one reference coding unit included in the picture 1600 may be determined according to the determination order of the coding unit.
- the image decoding apparatus 150 may determine determination orders 1604 and 1614 of at least one reference coding unit associated with each processing block 1602 and 1612. For example, when information on the determination order of the reference coding unit is obtained for each processing block, the reference coding unit determination order associated with each processing block 1602 and 1612 may be different for each processing block.
- the reference coding units included in the processing block 1602 may be determined according to the raster scan order.
- the reference coding unit determination order 1614 associated with another processing block 1612 is the reverse order of the raster scan order
- the reference coding units included in the processing block 1612 may be determined according to the reverse order of the raster scan order.
- FIG. 17 illustrates an image prediction apparatus 1700 which performs intra prediction of blocks included in an image.
- the image predicting apparatus 1700 includes a neighboring sample acquirer 1710, a reference sample determiner 1720, and a predictor 1730.
- a neighboring sample acquirer 1710 a reference sample determiner 1720
- a predictor 1730 a predictor 1730.
- the adjacent sample acquirer 1710, the reference sample determiner 1720, and the predictor 1730 are represented by separate structural units, the adjacent sample acquirer 1710 and the reference sample determiner according to an exemplary embodiment are illustrated.
- the 1720 and the predictor 1730 may be combined and implemented in the same component unit.
- the neighboring sample acquirer 1710, the reference sample determiner 1720, and the predictor 1730 are represented by structural units located in one device, the adjacent sample acquirer 1710 and the reference sample determiner 1720 are illustrated.
- the devices in charge of the functions of the predicting unit 1730 are not necessarily physically adjacent. Therefore, according to an exemplary embodiment, the adjacent sample acquirer 1710, the reference sample determiner 1720, and the predictor 1730 may be distributed.
- the adjacent sample obtainer 1710, the reference sample determiner 1720, and the predictor 1730 may be implemented by one processor according to an exemplary embodiment. In some embodiments, the present invention may also be implemented by a plurality of processors.
- the adjacent sample acquirer 1710, the reference sample determiner 1720, and the predictor 1730 may be stored in the form of a program in a storage medium of the image predicting apparatus 1700. Also, a program that performs functions of the adjacent sample acquirer 1710, the reference sample determiner 1720, and the predictor 1730 may be acquired from the outside as needed by the image predicting apparatus 1700.
- the functions performed by the adjacent sample acquirer 1710, the reference sample determiner 1720, and the predictor 1730 of FIG. 17 may be performed by the encoder 110 of FIG. 1A and the decoder 170 of FIG. 1B. have.
- the neighbor sample obtainer 1710 acquires a plurality of neighbor samples located around the current block. Neighbor samples are used to predict the samples included in the current block. Thus, reconstructed samples prior to reconstruction of the current block are obtained as adjacent samples.
- samples adjacent to the top of the current block are reconstructed before the current block, unless the current block is located at the top of the current picture. Therefore, among the samples included in the upper block of the current block, samples adjacent to the current block are included in the neighboring sample of the current block.
- samples adjacent to the left side of the current block are reconstructed before the current block. Therefore, among the samples included in the left block of the current block, samples adjacent to the current block are included in the neighboring sample of the current block.
- the right block of the current block is restored after the restoration of the current block. Therefore, when the direction of the intra mode of the current block is the right upper direction, adjacent samples of the current block are obtained from the right upper block of the current block instead of the right block of the current block. Specifically, the lowermost samples of the upper right block are included in the adjacent sample.
- the lower block of the current block is restored after the restoration of the current block. Therefore, when the direction of the intra mode of the current block is the lower left direction, adjacent samples of the current block are obtained from the lower left block of the current block instead of the lower block of the current block. Specifically, the rightmost samples of the lower left block are included in the adjacent sample.
- the neighboring sample obtainer 1710 may refer to the neighboring samples obtained from the restored block, and then may replace the position corresponding to the position of the neighboring samples of the unreconstructed block. substitution) may generate adjacent samples. If the current block is at the edge of the image or if the neighboring block is restored later than the current block according to the restoration order, the current block cannot refer to the neighboring block. Therefore, the adjacent sample acquirer 1710 marks adjacent samples of the reconstructed block as 'available' and displays adjacent samples corresponding to the unreconstructed block as 'not available'. The adjacent sample acquirer 1710 obtains sample values of neighboring samples indicated as 'available' from the neighboring block and 'available' adjacent samples marked as 'not available'. Replace with an adjacent neighboring sample determined from the neighboring samples indicated by.
- the alternate contiguous sample may be determined as the average value of the contiguous samples marked 'available'.
- the replacement contiguous sample may also be determined as the sample value of the contiguous sample labeled as closest available from the contiguous sample marked 'not available'.
- alternative contiguous samples can be determined in a variety of ways.
- the method of determining the replacement neighboring sample may be determined according to the attributes of the current block or higher data units of the current block.
- the method of determining the replacement neighboring sample may be determined by the most efficient method of the plurality of determination methods, regardless of the attributes of the current block or higher data units of the current block.
- the most efficient method of determining the replacement neighboring sample for the current block may be included in the bitstream in the form of a flag and transmitted from the encoder to the decoder.
- the adjacent sample acquirer 1710 may smooth the obtained adjacent samples according to the smoothing filter.
- the smoothing filter used for smoothing may be determined according to the degree of difference between adjacent samples. Whether adjacent samples are to be smoothed may be determined according to the size and intra mode of the current block. As the neighboring samples are smoothed, the values of the neighboring samples have continuity and the prediction accuracy can be increased.
- the reference sample determiner 1720 may generate a one-dimensional adjacent sample array including adjacent samples. Positions of adjacent samples are represented by x and y coordinate values. Therefore, in the process of retrieving the reference sample from the adjacent samples, the complexity of the calculation may be increased as two variables for the position of the adjacent sample are considered.
- the positions of the adjacent samples are expressed as x or y coordinate values.
- the position of the adjacent samples may be represented by the y coordinate value.
- An array including the transformed adjacent samples represented by one variable in a row is called a one-dimensional adjacent sample array. Since the position of the adjacent sample in the one-dimensional adjacent sample array is represented by one variable, the complexity of calculation may be reduced in the process of retrieving the reference sample from the one-dimensional adjacent sample array.
- the reference sample to which the current sample refers may be more easily determined. For example, when the neighboring samples obtained from the upper block and the neighboring samples obtained from the left block are used together in prediction of the current block, the coordinates of the neighboring samples are simplified in one dimension so that the reference sample to which the current sample is referred to is easy. Can be determined.
- Intra mode 0 and intra mode 1 indicate a planar mode and a DC mode, respectively.
- Planner mode and DC mode are non-directional intra modes.
- the 2 to 34 intra modes represent a directional directional intra mode. Since the reference number of the intra mode shown in Fig. 18A is set arbitrarily, a person skilled in the art can easily change the reference number.
- the one-dimensional adjacent sample array is composed of adjacent samples obtained from the left block and the lower left block.
- One-dimensional adjacent sample arrays are classified according to the y-coordinate value of adjacent samples.
- the intra mode 26 to the intra mode 34 only adjacent samples obtained from the upper block or the upper right block are used for prediction of the current block. Therefore, when the current block is predicted according to the intra mode 26 to the intra mode 34, the one-dimensional adjacent sample array is composed of adjacent samples obtained from the upper or right upper block. One-dimensional adjacent sample arrays are classified according to the x-coordinate value of adjacent samples.
- 18B shows a method for generating one-dimensional adjacent sample arrays for intra mode 18-25.
- the left neighboring samples 1830 of the current block 1800 are transformed into transform neighboring samples 1840 according to the direction 1802 of the intra mode of the current block.
- transform neighbor samples 1840 are determined from transform neighbor samples 1840 to be equal to left neighbor samples 1830 indicated by direction 1802 of the intra mode.
- transform adjacent sample 1882 of one-dimensional adjacent sample array 1810 is determined equally to left adjacent sample 1832 indicated by direction 1802 of intra mode from transform adjacent sample 1842.
- Upper neighbor samples 1820 and transform neighbor samples 1840 of the current block 1800 are included in the one-dimensional neighbor sample array 1810.
- Adjacent samples included in the one-dimensional adjacent sample array 1810 have the same y-coordinate value. Therefore, the positions of the samples of the one-dimensional adjacent sample array 1810 are divided according to the x-coordinate value. That is, the positions of the samples included in the one-dimensional adjacent sample array 1810 are represented by one reference value.
- the one-dimensional adjacent sample arrays are arranged vertically. Therefore, the upper neighboring samples are transformed and included in the one-dimensional neighboring sample array together with the left neighboring sample.
- the positions of adjacent samples of the one-dimensional adjacent sample array are distinguished according to the y-coordinate value.
- the reference sample determiner 1720 determines a reference sample to which the current sample refers to from the one-dimensional adjacent sample array composed of adjacent samples according to the intra mode of the current block. Specifically, the neighboring sample indicated by the direction of the intra mode of the current block from the current sample among the neighboring samples of the one-dimensional adjacent sample array is determined as the reference sample. In Figures 19A and 19B the method of determining the reference sample is described.
- 19A illustrates a method of determining a reference sample according to the position of the current sample and the intra mode of the current block.
- the current block 1900 is predicted by the intra mode 1920 in the diagonal direction.
- the adjacent sample 1912 located in the direction of the intra mode 1920 from the current sample 1902 is determined as the reference sample of the current sample 1902.
- the prediction value of the current sample 1902 is determined in the same manner as the adjacent sample 1912 that is the reference sample.
- the prediction block of the current block 1900 has a striped texture in the diagonal direction according to the prediction direction of the intra mode 1920.
- 19B illustrates a method of determining a reference sample of a current sample when the current sample refers to a subsample.
- the reference position of the reference sample indicated by the direction of the intra mode from the current sample has an integer value and a decimal value. If the fractional value is zero, the reference sample is determined as the adjacent sample of the one-dimensional adjacent sample array. However, if the decimal value is not zero, the reference sample may be determined as a subsample of the one-dimensional adjacent sample array. A subsample is a sample located between adjacent samples and determined by adjacent samples. If the current block is in the diagonal intra mode, it is highly likely that the reference sample is determined to be a subsample.
- the reference sample of the current sample 1950 is determined as the subsample 1960 indicated by the prediction direction of the diagonal mode 1970 in the diagonal direction from the current sample 1950.
- the subsample 1960 is positioned between the adjacent sample 1964 and the adjacent sample 1966, and a sample value of the subsample 1960 may be determined according to the adjacent sample 1964 and the adjacent sample 1966.
- the sample value of the subsample 1960 may be determined according to linear interpolation using the decimal values of the reference position and the adjacent samples 1964 and 1966.
- the sample value of the subsample 1960 may be determined according to spline interpolation or DCT based interpolation using the fractional value of the reference position and the adjacent samples 1962, 1964, 1966, and 1968.
- the generated subsample is determined as a reference sample and used for prediction of the current sample.
- the prediction unit 1730 adjusts a sample value of the reference sample according to a reference distance, and determines the adjusted sample value of the reference sample as a prediction value of the current sample.
- the reference distance is determined based on the distance between the reference sample and the current sample. For example, the distance between the reference sample and the current sample may be determined as the reference distance. Also, for ease of calculation, one of the horizontal distance and the vertical distance between the reference sample and the current sample may be determined as the reference distance.
- the horizontal distance means the difference between the x component of the position of the reference sample and the current sample
- the vertical distance means the difference between the y component of the position of the reference sample and the current sample.
- the horizontal distance when the horizontal distance is greater than the vertical distance, the horizontal distance may be determined as the reference distance.
- the vertical distance when the vertical distance is larger than the horizontal distance, the vertical distance may be determined as the reference distance. Therefore, when the intra mode is a horizontal directional intra mode close to the horizontal mode, the reference distance is defined as the horizontal distance between the reference sample and the current sample. In contrast, when the intra mode is a vertical directional intra mode close to the vertical mode, the reference distance is defined as the vertical distance between the reference sample and the current sample.
- the reference sample can be adjusted according to the reference distance. If the reference distance is small, the relationship between the current sample and the reference sample is high. Thus, the current sample is likely to have the same value as the reference sample. Therefore, even if the current sample is predicted according to the reference sample, the probability of generating a large prediction error is low.
- the reference distance when the reference distance is large, the relationship between the current sample and the reference sample is relatively small. Therefore, when the current sample is predicted according to the reference sample, the probability of occurrence of a large prediction error may be increased, thereby lowering the invalidation rate. Therefore, the larger the reference distance, the greater the need to adjust the reference sample to reduce the prediction error.
- the direction of the intra mode may be additionally taken into account in the adjustment of the reference sample.
- the direction of the intra mode is a diagonal direction, the difference between the actual distance and the reference distance between the reference sample and the current sample may be large. Therefore, the reference sample may be adjusted in consideration of the direction of the intra mode for accurate prediction.
- the reference sample may be adjusted according to the adjacent sample representative value and the reference distance or by a smoothing filter according to the reference distance. Due to the adjustment of the reference sample, the sample value of the reference sample may be changed.
- the adjustment method according to the adjacent sample representative value and the reference distance will be described with reference to Figs. 20 and 1, and the adjustment method by the smoothing filter according to the reference distance will be described with reference to Figs. 21A, 21B and Equation 2. .
- the prediction unit 1730 may determine a neighbor sample representative value representing the plurality of neighbor samples, and adjust the sample value of the reference sample according to the neighbor sample representative value and the reference distance.
- the prediction unit 1730 may determine the prediction value of the current sample according to the sample value of the reference sample and the representative sample representative value.
- the reference sample adjusting method according to the adjacent sample representative value and the reference distance is described based on Equation 1 and FIG.
- the contiguous sample representative value is determined from a plurality of contiguous samples included in the one-dimensional contiguous sample array.
- the adjacent sample representative value is determined as the average of at least two adjacent samples including the reference sample.
- the neighbor sample representative value may be determined as a local average of the sample value of the reference sample and the sample values of adjacent samples adjacent to the reference sample.
- an average of sample values of a reference sample, an adjacent sample located immediately to the left of the reference sample, and an adjacent sample located immediately to the right of the reference sample may be determined as the adjacent sample representative value.
- the number of adjacent samples used to determine the neighbor sample representative value may be determined according to the size of the current block. If the size of the current block is small, the average of two to three adjacent samples may be determined as the adjacent sample representative value. On the other hand, when the size of the current block is large, an average of four or more adjacent samples may be determined as the adjacent sample representative value in proportion to the size of the current block.
- the number of neighboring samples may be adaptively determined from encoding information obtained from the current block or neighboring blocks of the current block.
- the adjacent sample representative value may be determined as an average of all adjacent samples included in the one-dimensional adjacent sample array. Therefore, all adjacent sample representative values used for prediction of the current block may be determined to be the same value.
- a prediction value of the current sample may be determined according to the reference sample and the neighbor sample representative value.
- the prediction value of the current sample is determined by the weighted average of the sample value of the reference sample and the representative sample representative value. Therefore, the reference sample may be adjusted according to the weight of the reference sample and the adjacent sample representative value. For example, if the weight of the reference sample is greater than the weight of the adjacent sample representative value, the reference sample is adjusted slightly. On the contrary, when the weight of the reference sample is smaller than the weight of the adjacent sample representative value, the reference sample is adjusted to a large width.
- the weights used for the weighted average may be determined according to the reference distance.
- the weight of the reference sample is determined to be larger than the weight of the representative sample representative value.
- the weight of the adjacent sample representative value is determined to be greater than the weight of the reference sample. Therefore, as the reference distance increases, the weight of the reference sample decreases and the weight of the adjacent sample representative value increases.
- the direction of the intra mode may be reflected in the determination of the weight for the reference sample and the adjacent sample representative value. For example, when the direction of the intra mode is the diagonal direction, the weight for the adjacent sample representative value may increase.
- the weight of the adjacent sample representative value may increase linearly.
- the weight of the adjacent sample representative value may increase non-linearly or piece-wise linearly.
- the weight of the reference sample may decrease linearly, nonlinearly, or interval linearly with increasing reference distance.
- the weight of the reference sample and the neighbor sample representative value may be determined as a weight determined that the least prediction error occurs according to the statistical result.
- Adjustment of the reference sample according to the reference distance may be performed according to Equation 1 below.
- A means the sample value of the reference sample and DC means the adjacent sample representative value.
- S means the sum of the weights of the reference samples and the weights of the adjacent sample representatives, and w means the weights of the neighboring sample representatives.
- S may be determined as the length of the side of the current block or a multiple of the length of the side. In addition, S may be determined according to the actual distance between the reference sample and the current sample in consideration of the direction of the intra mode.
- w is determined to be less than S. Therefore, the weights of the reference sample and the adjacent sample representative value are determined to be greater than zero. And the maximum value of w can be determined to be equal to or less than S. Therefore, the weight S-w of the reference sample may always be set to be greater than zero.
- w is set to increase with reference distance. w may be set to increase linearly in proportion to the reference distance. In addition, when it is determined that the linear increase of w is not optimal according to the statistical result of the reference distance and the prediction error, w may be set to increase non-linearly or distinctly linearly. The value of w may be arbitrarily determined according to the statistical result regarding the reference distance and the prediction error.
- w may be determined according to the same determination method for all blocks.
- w may be adaptively determined according to the characteristics of the current block or may be determined according to information transmitted from the bitstream.
- DC may be determined as an average of all adjacent samples included in the one-dimensional adjacent sample array.
- DC may be determined as a region average of a reference sample and adjacent samples adjacent to the reference sample. The number of adjacent samples required for the calculation of the region average may be determined according to the size of the current block.
- FIG. 20 An embodiment of a method of adjusting a sample value of a reference sample according to the reference distance and adjacent sample representative value described above is described according to FIG. 20.
- FIG. 20 illustrates an embodiment of a method of adjusting a sample value of a reference sample according to a reference distance and a representative sample representative value in the vertical directional intra mode.
- a one-dimensional adjacent sample arrangement 2010 is determined that includes adjacent samples of the current block 2000.
- the one-dimensional representative value array 2020 including the adjacent sample representative value obtained from the adjacent samples included in the one-dimensional adjacent sample array 2010 is obtained.
- the one-dimensional adjacent sample array 2010 and the one-dimensional representative value array 2020 are arranged in the horizontal direction.
- the reference sample 2012 used for prediction of the current sample 2002 is determined from the one-dimensional adjacent sample array 2010 according to the intra mode 2006 applied to the current block 2000.
- the adjacent sample representative value 2022 corresponding to the reference sample 2012 is determined from the one-dimensional representative value array 2020.
- the reference distance 2004 of the reference sample 2012 is the current sample 2002.
- the sample value of the reference sample 2012 may be adjusted according to the reference distance 2004 and the adjacent sample representative value 2022 with reference to Equation (1).
- the adjacent sample representative value 2022 may be an average of all adjacent samples included in the one-dimensional adjacent sample array 2010 or an area average of adjacent samples adjacent to the reference sample 2012 in the one-dimensional adjacent sample array 2010.
- the weight for the reference sample 2012 and the weight for the adjacent sample representative value 2022 are determined according to the reference distance 2004.
- the weight of the adjacent sample representative value 2022 is determined to be equal to the reference distance 2004, the reference distance 2004 is 5, and the weights of the weights of the adjacent sample representative value 2022 and the reference sample 2012 are determined.
- the weight of the adjacent sample representative value 2022 may be 5 and the weight of the reference sample 2012 may be 3.
- the sum of the weights of the sample value of the reference sample 2012 and the neighboring sample representative value 2022 may be determined according to the size of the current block. However, the sum of the weights of the reference sample 2012 and the adjacent sample representative value 2022 may be determined by other characteristics of the current block, or may be set to have a fixed value regardless of the size of the current block.
- the current sample 2002 is predicted according to the reference sample 2012 adjusted according to the adjacent sample representative value 2022 and the reference distance 2004. Specifically, the prediction value of the current sample 2002 is determined to be the same value as the sample value of the adjusted reference sample 2012.
- the reference sample adjusting method according to the reference distance and the adjacent sample representative value has been described above.
- a method of adjusting a reference sample using a smoothing filter according to a reference distance in the reference sample to adjust the reference sample is described.
- the prediction unit 1730 may smooth the sample value of the reference sample by using a smoothing filter selected according to the reference distance.
- the prediction unit 1730 may determine the sample value of the smoothed reference sample as a prediction value of the current sample. Smoothing herein means adjusting the sample value of the reference sample so that the sample value of the reference sample has continuity with the sample values of the samples adjacent to the reference sample.
- the smoothing filter is an N-tap filter containing N filter coefficients.
- the smoothing filter is a three-tap filter containing smoothing filter coefficients of [1 / 4,2 / 4,1 / 4], and the smoothing filter is adjacent sample P (X-1) located just to the left of the reference sample.
- the adjacent sample P (X + 1) located just to the right of the reference sample the reference sample to which the smoothing filter is applied is ⁇ P (X-1) + 2 * P (X) + P (X + 1) ⁇ / 4.
- the number of filter coefficients may be determined according to at least one of the size of the current block, the reference distance, and the intra mode. As the size of the current block increases, the number of filter coefficients included in the smoothing filter may increase. In addition, the number of filter coefficients may be determined according to the reference distance and the intra mode.
- the filter coefficient can be determined according to the smoothing strength.
- the filter coefficient assigned to the reference sample may be set to be larger than the filter coefficient assigned to adjacent samples of the reference sample.
- the filter coefficient assigned to the reference sample may be set to be the same as the filter coefficient assigned to adjacent samples of the reference sample.
- the smoothing intensity can be set to increase as the reference distance increases.
- the smoothing intensity may be set to increase linearly in proportion to the reference distance.
- the smoothing intensity may be set to increase nonlinearly or interval linearly as the reference distance increases.
- the smoothing intensity may be arbitrarily determined according to statistical results regarding the reference distance and the prediction error.
- Smoothing can be performed by applying the smoothing filter to the reference sample several times. For example, when the reference distance is 1, the smoothing filter may be applied to the reference sample once, and when the reference distance is 2, the smoothing filter may be applied to the reference sample twice.
- the same smoothing filter can be used in duplicate for smoothing the reference sample.
- different smoothing filters may be used successively depending on the reference distance.
- FIG. 21A an embodiment of a smoothing filter according to a reference distance is described.
- the intra block 2101 in the vertical direction is applied to the current block 2100.
- the reference samples of P0 to P7 are all determined to be adjacent samples B located in the same column as P0 to P7.
- Reference samples of P0 to P7 are adjusted according to the smoothing filter according to the reference distances of P0 to P7, respectively.
- the reference distance of P0 to P7 is determined by the vertical distance from the adjacent sample B. For example, the reference distance of P0 is determined as 1 and the reference distance of P1 is determined as 2.
- Smoothing filters are selected according to the reference distance of P0 to P7.
- the smoothing filter having the reference distance of 1 is [0, 1, 0]
- the smoothing filter for P0 may be determined as [0, 1, 0].
- the smoothing filter having the reference distance of 4 is [1 / 4,1 / 2,1 / 4]
- the smoothing filter for P4 may be determined as [1 / 4,1 / 2,1 / 4].
- the smoothing filter having a reference distance of 8 is [1/3, 1/3, 1/3]
- the smoothing filter for P7 may be determined as [1/3, 1/3, 1/3].
- the smoothing intensity of the smoothing filter applied to the reference samples of P0 to P7 is designed to increase as the reference distance of P0 to P7 increases.
- the smoothing filter is described as a three tap filter with three filter coefficients in FIG. 21A, the smoothing filter may have more filter coefficients.
- the number of filter coefficients may be determined according to the intra mode or the size of the current block.
- P0 to P7 may be adjusted by applying a smoothing filter to adjacent samples A, B, and C included in one-dimensional adjacent sample array 2110.
- the adjacent sample B is used for smoothing the reference sample as the reference sample of P0 to P7
- the adjacent samples A and C are adjacent samples adjacent to the adjacent sample B which is the reference sample.
- P0 with a small reference distance is not smoothed because the smoothing filter of [0, 1, 0] is applied.
- smoothing according to a smoothing filter may be performed on samples having a large reference distance.
- P4 applies a smoothing filter of [1/4, 1/2, 1/4], so P4 is (1/4) * A + (1/2) * B + (1/4) * Can be adjusted equally to C.
- P7 applies a smoothing filter of [1/3, 1/3, 1/3], so P7 is (1/3) * A + (1/3) * B + (1/3) * C Can be adjusted in the same manner as P1, P2, P3, P5 and P6 may also be adjusted by the smoothing filter according to the reference distance.
- the method described in FIG. 21A can also be applied to the intra mode in the other direction.
- the method described in FIG. 21A can also be applied to current blocks of other sizes.
- the prediction unit 1730 may determine a sample value of the smoothed reference sample as a prediction value of the current sample.
- the smoothing filter is defined with respect to the reference distance of the current sample
- the sample value of the smoothed reference sample is determined as the prediction value of the current sample according to the smoothing filter of the current sample.
- the prediction unit 1730 may adjust the sample value of the reference sample by using the smoothing filter defined for another reference distance.
- the prediction unit 1730 may search for the first distance and the second distance for which the smoothing filter is defined.
- the first distance is less than the reference distance of the current sample, and the second distance is greater than the reference distance of the current sample.
- the difference between the first distance and the reference distance and the difference between the second distance and the reference distance are preferably small.
- the prediction unit 1730 may obtain a first intermediate value by smoothing the sample value of the reference sample according to the smoothing filter for the first distance. Similarly, the prediction unit 1730 may obtain a second intermediate value by smoothing the sample value or the first intermediate value of the reference sample according to the smoothing filter for the second distance.
- the prediction unit 1730 may determine the prediction value of the current sample using the first intermediate value and the second intermediate value. For example, the weighted average of the first median and the second median may be determined as the predicted value of the current sample. In order to determine the weight of the first intermediate value and the second intermediate value, the ratio of the difference between the first distance and the reference distance and the difference between the second distance and the reference distance may be considered.
- the prediction unit 1730 may additionally search for a third distance, a fourth distance, etc. in which the smoothing filter is defined, and obtain a third intermediate value and a fourth intermediate value according to the third distance, the fourth distance, and the like.
- the prediction value of the current sample may be determined using three or more intermediate values.
- the adjustment of the reference sample according to the reference distance may be performed according to Equation 2 below.
- a [i] means the first intermediate value
- a [i + 1] means the second intermediate value.
- x means a weight of the first intermediate value
- y means a weight of the second intermediate value.
- a 'me ans the adjusted reference sample.
- x is determined according to the difference between the first distance and the reference distance. x may be determined to decrease as the difference between the first distance and the reference distance increases. y is determined according to the difference between the second distance and the reference distance. y may be determined to decrease as the difference between the second distance and the reference distance increases. Also, x and y may be determined according to an interpolation method for determining A '.
- the prediction unit 1730 may predict all samples included in the current block according to the reference sample adjusting method according to the smoothing filter described above.
- 21B illustrates an embodiment of a prediction method of the current block 2120 when only a smoothing filter for a specific reference distance is defined.
- the current block 2120 is predicted according to the direction of the intra mode 2122. All adjacent samples A are determined to be reference samples for P0 to P7 included in the current block.
- a smoothing filter is defined only for a reference distance of multiples of two. Therefore, by predicting a sample value of the adjacent sample A, which is a reference sample, according to a smoothing filter, prediction values of P1, P3, P5, and P7 can be obtained.
- P3 may be obtained by smoothing P1, P5 by P3, and P7 by P5 sequentially.
- a prediction value can be obtained from P0 from adjacent samples A and P1, P2 from P1 and P3, P4 from P3 and P5, and P6 from P5 and P7. Therefore, continuity is given to the predicted values of P0 to P7.
- samples of the current block 2120 may be predicted according to the method described above.
- Samples located in the second column 2134, the fourth column 2138, the sixth column 2142, and the eighth column 2146 may be predicted by smoothing adjacent samples of the one-dimensional adjacent sample array 2130 according to a smoothing filter. Can be.
- the samples in the fourth row 2138 are samples in the second row 2134
- the samples in the sixth row 2142 are samples in the fourth row 2138
- the samples in the eighth row 2146 are sixth. This can be predicted by smoothing the samples in column 2142.
- the samples located in the first row 2132, the third row 2136, the fifth row 2140, and the seventh row 2144 are arranged in the second row 2134, the fourth row 2138, and the sixth row ( 2142), and may be predicted based on the samples located in the eighth column 2146.
- a smoothing filter may be defined with respect to a multiple of 4 or 8 as the reference distance.
- the reference distance at which the smoothing filter is defined may be determined irregularly.
- the adjustment method of FIGS. 20 to 21B differs only in the calculation process, and consequently, the same adjustment result can be derived. Therefore, the adjustment method of Figs. 20 to 21B can be mutually compatible.
- the prediction unit 1730 predicts the current block 2120 according to the above-described reference sample adjustment method, and then predicts the prediction value of the samples included in the current block 2120 by the intra mode of the current block 2120. It can be smoothed using a one-dimensional filter or a two-dimensional filter in the vertical direction of. And whether to smooth the prediction value of the samples included in the current block 2120 is determined by the information indicating whether to smooth the prediction value, the size and shape of the current block 2120, intra of the current block 2120 It may be determined according to the mode. According to an embodiment, the prediction unit 1730 may smooth the prediction values of all the samples included in the current block 2120. According to another embodiment, the prediction unit 1730 may smooth only the prediction values of some discontinuous samples in the current block 2120. For example, if some of the adjacent samples are discontinuous, only the prediction values of the samples predicted from the discontinuous adjacent samples may be smoothed.
- the prediction unit 1730 may determine whether the reference sample is adjusted to intra prediction of the current block. Therefore, when it is determined that the reference sample is adjusted to the prediction of the current block, the prediction unit 1730 predicts the current sample based on the reference sample adjusted according to the reference distance. On the contrary, when the reference sample is not adjusted in the prediction of the current block, the prediction unit 1730 does not consider the reference distance and predicts the current sample according to the reference sample.
- the encoder 110 compares encoding efficiency when the reference sample is adjusted to intra prediction of the current block and when it is not adjusted. It is determined whether the reference sample is adjusted to intra prediction of the current block.
- the encoder 110 generates reference sample adjustment information indicating whether a reference sample is adjusted to intra prediction of the current block, and the output unit 120 of FIG. 1A outputs a bitstream including the reference sample adjustment information. .
- the reference sample adjustment information may be generated for a higher data unit including the prediction unit or the prediction unit.
- the reference sample adjustment information may be generated for a coding unit, a maximum coding unit, a slice, a picture, and the like, which are higher data units of the prediction unit.
- Reference sample adjustment information can also be generated for two types of data units.
- the first reference sample adjustment information may be generated for the upper data unit, and the second reference sample adjustment information may be generated for the lower data unit.
- the first reference sample adjustment information may indicate whether adjustment of the reference sample is allowed for a higher data unit.
- the second reference sample adjustment information may indicate whether the adjustment of the reference sample is performed on the lower data unit included in the upper data unit. For example, when the first reference sample adjustment information generated for the upper data unit does not allow adjustment of the reference sample, the adjustment of the reference sample is not allowed for all lower data units included in the upper data unit. Therefore, the second reference sample adjustment information is not generated for all lower data units.
- the second reference flattening information indicating whether adjustment of the reference sample is performed on the lower data unit is performed for all lower data units included in the upper data unit. Is generated.
- the first reference sample adjustment information may indicate whether adjustment of the reference sample is necessarily performed on the higher data unit.
- the second reference sample adjustment information may indicate whether adjustment of the reference sample is performed on the lower data unit included in the upper data unit.
- the first reference sample adjustment information generated for the upper data unit indicates that the adjustment of the reference sample is necessarily performed
- the adjustment of the reference sample is performed for all lower data units included in the upper data unit. Therefore, the second reference sample adjustment information is not generated for all lower data units.
- a second reference indicating whether adjustment of the reference sample is performed on the lower data unit for each lower data unit included in the upper data unit is performed. Sample adjustment information is generated.
- the first reference sample adjustment information when the reference sample adjustment is performed on all the lower data units, may be performed when the reference sample adjustment is not performed on all the lower data units. And may be generated to indicate one of the cases determined by the second reference sample adjustment information of.
- the upper data unit of the above embodiment may include a sequence, a picture, a slice, and the like
- the lower data unit may include a maximum coding unit, a coding unit, a prediction unit, and the like.
- the encoder 110 may apply a reference sample adjustment to intra prediction of the current block when a specific condition for the current block and higher data units of the current block is satisfied.
- the encoder 110 may be set to apply the reference sample adjustment when the current block has a predetermined size or more.
- the coding efficiency obtained by adjusting the reference sample may be low. Accordingly, reference sample adjustment may be performed on a block of a large size having high coding efficiency according to the reference sample adjustment.
- the encoding unit 110 is configured such that reference sample adjustment is applied only to I slices using only intra prediction, and reference sample adjustment is not applied to P slices or B slices in which inter prediction and intra prediction are used together. Can be.
- whether the reference sample adjustment is applied may be determined according to whether the color component of the current block is a luma component or a chroma component. In addition, depending on which layer the current block is included in the multi-layer image, whether to apply the reference sample adjustment may be determined. In addition, whether or not to apply the reference sample adjustment may be determined according to various attributes of the current block and higher data units of the current block.
- Encoding unit 110 encodes when the reference sample is adjusted to intra prediction of the current block and is not adjusted only when it is not possible to determine whether to apply the reference sample adjustment only by the attributes of the current block and higher data units of the current block. The efficiency can be compared to determine whether the reference sample is adjusted to intra prediction of the current block. Therefore, when the encoding unit 110 cannot determine whether to apply the reference sample adjustment only by the attributes of the current block and the higher data unit of the current block, the reference sample adjustment indicating whether the reference sample is adjusted for intra prediction of the current block. Information can be generated. Therefore, the coding efficiency can be improved because the amount of generation of the reference sample adjustment information is reduced compared to the embodiment of generating the reference sample adjustment information for all blocks.
- the function of the image prediction apparatus 1700 is the decoder 170 of FIG. 1B.
- the decoder 170 may determine whether adjustment of the reference sample is performed on the current block according to the reference sample adjustment information acquired by the receiver 160 of FIG. 1B. Also, the decoder 170 may determine whether adjustment of the reference sample is performed on the current block according to the property of the current block or higher data units of the current block. Since the encoder 110 and the decoder 170 correspond to each other, a description of a method of determining whether to perform reference sample adjustment of the decoder 170 is omitted.
- 22 is a flowchart illustrating a method of predicting a current sample by adjusting a reference sample of the current sample according to a reference distance of the current sample.
- step 2210 a plurality of adjacent samples located around the current block are obtained. If a neighboring sample of a specific position cannot be obtained from the neighboring block, the neighboring sample of the specific position is generated using the obtained neighboring sample. And adjacent samples may be smoothed according to the degree of difference between adjacent samples. According to the intra mode of the current block, a one-dimensional adjacent sample array including adjacent samples may be determined.
- the neighboring sample indicated by the direction of the intra mode of the current block among the plurality of neighboring samples is determined as the reference sample. If the direction of the intra mode from the current sample points to a subsample between adjacent samples, the subsample may be determined as the reference sample.
- step 2230 the reference sample is adjusted according to the reference distance, and the current sample is predicted according to the adjusted reference sample.
- the reference sample may be adjusted according to the adjacent sample representative value and the reference distance.
- the reference sample can also be adjusted by the smoothing filter according to the reference distance.
- the neighbor sample representative value representing the plurality of neighbor samples is first determined.
- the reference sample is then adjusted according to the weighted average of the reference sample and the adjacent sample representative value.
- the current sample is then predicted according to the adjusted reference sample.
- the adjacent sample representative value may be determined as an average of all adjacent samples included in the one-dimensional adjacent sample array.
- the adjacent sample representative value may be determined as an area average of at least two or more adjacent samples including the reference sample. The number of adjacent samples used for the determination of the region mean is determined according to the size of the current block.
- the weight of the reference sample decreases and the weight of the neighboring sample representative value increases.
- the reference sample is adjusted by the smoothing filter according to the reference distance
- the reference sample is smoothed using the smoothing filter selected according to the reference distance, and based on the smoothed reference sample, the current sample is predicted.
- the smoothing intensity of the smoothing filter may be set to increase as the reference distance increases.
- the first and second distances for which the smoothing filter is defined may be searched.
- the first intermediate value may be determined by smoothing the reference sample using the first smoothing filter selected according to the first distance.
- the second intermediate value can be determined by smoothing the reference sample or the first intermediate value using a second smoothing filter selected according to the second distance.
- the prediction value of the current sample may be interpolated using the first intermediate value and the second intermediate value.
- Whether to adjust the reference sample may be determined according to the current block or higher data units of the current block. It may also be determined according to reference sample adjustment information for the current block.
- the current sample can be predicted more accurately.
- the above-described embodiments of the present invention can be written as a program that can be executed in a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium.
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Abstract
Description
Claims (15)
- 현재 블록의 주변에 위치한 복수의 인접 샘플들을 획득하는 단계;상기 복수의 인접 샘플들 중 상기 현재 블록의 인트라 모드의 방향이 가리키는 인접 샘플을 현재 샘플이 참조할 참조 샘플로 결정하는 단계; 및상기 참조 샘플의 샘플 값을 상기 참조 샘플과 상기 현재 샘플 간의 거리를 나타내는 참조 거리에 따라 조정하고, 조정된 참조 샘플의 샘플 값을 상기 현재 샘플의 예측 값으로 결정하는 단계를 포함하는 영상 예측 방법.
- 제1항에 있어서,상기 예측 값 결정 단계는,상기 복수의 인접 샘플들을 대표하는 인접 샘플 대표값을 결정하는 단계;상기 참조 샘플의 샘플 값과 상기 인접 샘플 대표값의 가중 평균에 따라 상기 현재 샘플을 예측하는 단계를 포함하고,상기 가중 평균에 이용되는 가중치들은 상기 참조 거리 및 상기 인트라 모드가 가리키는 방향 중 적어도 하나에 따라 결정되는 것을 특징으로 하는 영상 예측 방법.
- 제2항에 있어서,상기 참조 거리가 증가할수록, 상기 참조 샘플의 샘플 값의 가중치는 감소하고, 상기 인접 샘플 대표값의 가중치는 증가하는 것을 특징으로 하는 영상 예측 방법.
- 제2항에 있어서,상기 인접 샘플 대표값은, 상기 복수의 인접 샘플들의 샘플 값들의 평균으로 결정되는 것을 특징으로 하는 영상 예측 방법.
- 제2항에 있어서,상기 인접 샘플 대표값은, 상기 참조 샘플을 포함한 적어도 두 개 이상의 인접 샘플들의 샘플 값들의 평균으로 결정되고,상기 인접 샘플 대표값의 결정에 사용되는 인접 샘플들의 수는 상기 현재 블록의 크기에 따라 결정되는 것을 특징으로 하는 영상 예측 방법.
- 제1항에 있어서,상기 예측 값 결정 단계는,상기 참조 거리에 따라 선택된 평활화 필터(smoothing filter)를 이용하여 상기 참조 샘플의 샘플 값을 평활화(smoothing)하는 단계; 및상기 평활화된 참조 샘플의 샘플 값을 상기 현재 샘플의 예측 값으로 결정하는 단계를 포함하는 것을 특징으로 하는 영상 예측 방법.
- 제6항에 있어서,상기 참조 거리가 증가할수록, 상기 평활화 필터의 평활화 강도가 증가하는 것을 특징으로 하는 영상 예측 방법.
- 제6항에 있어서,상기 참조 샘플 평활화 단계는,상기 참조 거리에 대한 평활화 필터가 정의되지 않은 경우, 평활화 필터가 정의된 제1거리 및 제2거리를 검색하는 단계;상기 제1 거리에 따라 선택된 제1 평활화 필터를 이용하여 상기 참조 샘플을 평활화함으로써 제1 중간값을 결정하고, 상기 제2 거리에 따라 선택된 제2 평활화 필터를 이용하여 상기 참조 샘플 또는 상기 제1 중간값을 평활화함으로써 제2 중간값을 결정하는 단계; 및상기 제1 중간값 및 제2 중간값의 가중 평균을 상기 현재 샘플의 예측 값으로 결정하는 단계를 포함하는 영상 예측 방법.
- 제1항에 있어서,상기 인트라 모드가 수평 방향성 인트라 모드인 경우, 상기 참조 거리는 상기 참조 샘플과 상기 현재 샘플의 수평 거리이고,상기 인트라 모드가 수직 방향성 인트라 모드인 경우, 상기 참조 거리는 상기 참조 샘플과 상기 현재 샘플의 수직 거리인 것을 특징으로 하는 영상 예측 방법.
- 제1항에 있어서,상기 참조 샘플 결정 단계는,상기 현재 샘플로부터 상기 인트라 모드의 방향이 두 인접 샘플들 사이의 서브 샘플을 가리킬 경우, 상기 서브 샘플에 인접한 인접 샘플들에 기초하여 참조 샘플을 결정하는 것을 특징으로 하는 영상 예측 방법.
- 제1항에 있어서,상기 영상 예측 방법에 있어서,상기 현재 블록의 예측에 상기 참조 샘플의 샘플 값의 조정이 수행되는지 여부를 결정하는 단계가 더 포함되고상기 예측 단계는,상기 참조 샘플의 샘플 값의 조정이 수행되는 것으로 결정될 때, 상기 참조 샘플의 샘플 값을 조정하여 상기 현재 샘플을 예측하고,상기 참조 샘플의 샘플 값의 조정이 수행되지 않는 것으로 결정될 때, 상기 참조 샘플의 샘플 값을 조정하지 않고 상기 현재 샘플을 예측하는 것을 특징으로 하는 영상 예측 방법.
- 제11항에 있어서,상기 참조 샘플의 샘플 값의 조정이 수행되는지 여부를 결정 단계는,상기 현재 블록의 예측에 상기 참조 샘플의 샘플 값의 조정이 수행되는지 여부를 나타내는 참조 샘플 조정 정보를 획득하는 단계 및상기 참조 샘플 조정 정보에 따라 상기 현재 블록의 예측에 상기 참조 샘플의 샘플 값의 조정이 수행되는지 여부를 결정하는 단계를 포함하는 것을 특징으로 하는 영상 예측 방법.
- 제11항에 있어서,상기 상기 참조 샘플 조정이 수행되는지 여부를 결정 단계는,상기 현재 블록의 크기 정보, 상기 현재 블록의 색 정보, 상기 현재 블록에 허용되는 예측 방법에 대한 예측 방법 정보 중 적어도 하나에 의하여 상기 참조 샘플의 조정이 수행되는지 여부를 결정하는 것을 특징으로 하는 영상 예측 방법.
- 현재 블록의 주변에 위치한 복수의 인접 샘플들을 획득하는 인접 샘플 획득부;상기 복수의 인접 샘플들 중 상기 현재 블록의 인트라 모드의 방향이 가리키는 인접 샘플을 현재 샘플이 참조할 참조 샘플로 결정하는 참조 샘플 결정부; 및상기 참조 샘플의 샘플 값을 상기 참조 샘플과 상기 현재 샘플 간의 거리를 나타내는 참조 거리에 따라 조정하고, 조정된 참조 샘플의 샘플 값을 현재 샘플의 예측 값으로 결정하는 예측부를 포함하는 영상 예측 장치.
- 제1항의 영상 예측 방법을 실행하기 위한 프로그램이 기록된 컴퓨터로 판독 가능한 기록 매체.
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Also Published As
Publication number | Publication date |
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JP2019508944A (ja) | 2019-03-28 |
EP3393126A4 (en) | 2019-04-17 |
KR20180107087A (ko) | 2018-10-01 |
RU2018132742A (ru) | 2020-03-17 |
US20210195199A1 (en) | 2021-06-24 |
CN108702502A (zh) | 2018-10-23 |
US11277615B2 (en) | 2022-03-15 |
EP3393126A1 (en) | 2018-10-24 |
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