Abstract: An image decoding method includes: comparing a size of a current image including a current block with a size of a reference image; selecting, in the reference image, reference samples corresponding to current samples in the current block according to a motion vector of the current block; and reconstructing the current block based on the reference samples, wherein, when the size of the reference image is greater than the size of the current image, the reference samples are spaced apart from one another in the reference image by an interval corresponding to a result of the size comparison.

Abstract: An image encoding and decoding method and apparatus are provided. The image decoding method includes obtaining a difference quantization parameter for a current coding unit from a bitstream, based on an area of a predefined difference quantization parameter signaling unit; obtaining a quantization parameter for the current coding unit by using a predicted quantization parameter for the current coding unit and the difference quantization parameter for the current coding unit; obtaining at least one inverse-quantized coefficient by performing inverse-quantization on at least one coefficient obtained based on residual information of the current coding unit included in the bitstream, based on the quantization parameter for the current coding unit; obtaining a residual block of the current coding unit, based on the inverse-quantized coefficient; and obtaining a reconstructed block of the current coding unit, based on the residual block of the current coding unit.

Abstract: An image decoding method includes obtaining, from a bitstream, first information indicating a motion vector resolution of a current unit among plural motion vector resolutions including a first motion vector resolution and a second motion vector resolution, and obtaining, from the bitstream, second information indicating whether a merge mode is applied to the current unit or not when the first information indicates the first motion vector resolution. The current unit is decoded based on the merge mode when the second information indicates that the merge mode is applied to the current unit. When the first information indicates the second motion vector resolution, the second information is not obtained from the bitstream.

Abstract: A video decoding method, including obtaining, from a bitstream, information indicating a prediction type of a coding unit including a current block; obtaining, from the bitstream, coded block flag (CBF) information for a Cr component of the current block and CBF information for a Cb component of the current block; determining a weight of a residual sample of the Cr component and a weight of a residual sample of the Cb component, based on the prediction type of the coding unit, the CBF information for the Cr component, and the CBF information for the Cb component; obtaining, from the bitstream, a chroma joint residual sample of the current block; and reconstructing the residual sample of the Cr component by using the chroma joint residual sample of the current block and the weight of the residual sample of the Cr component, and reconstructing the residual sample of the Cb component by using the chroma joint residual sample of the current block and the weight of the residual sample of the Cb component.

Abstract: According to an embodiment of the disclosure, a video decoding method includes obtaining, from a bitstream, information indicating a first difference between a maximum size of a coding unit of which a width and a height have a ratio of 1:4 and a size of a largest coding unit, determining the maximum size of the coding unit of which the width and the height have a ratio of 1:4 by using the size of the largest coding unit and the first difference, determining a minimum size of the coding unit of which the width and the height have a ratio of 1:4 based on a minimum size of a coding unit, determining whether it is possible to generate a coding unit of which a width and a height have a ratio of 1:4 by splitting a first coding unit based on the maximum size and the minimum size of the coding unit of which the width and the height have a ratio of 1:4, and determining a second coding unit including the coding unit of which the width and the height have a ratio of 1:4, from the first coding unit, and decoding the seco

Abstract: Provided is an image decoding method including: determining a first coding block and a second coding block corresponding to the first coding block; when a size of the first coding block is equal to or smaller than a preset size, obtaining first split shape mode information and second split shape mode information from a bitstream, determining a split mode of the first coding block, based on the first split shape mode information, and determining a split mode of the second coding block, based on the second split shape mode information; and decoding a coding block of a first color component which is determined based on the split mode of the first coding block and a coding block of a second color component which is determined based on the split mode of the second coding block.

Abstract: A method and apparatus for, in a video encoding and decoding procedure, selecting a candidate motion vector of a current block from a motion vector candidate list of the current block, determining a motion vector of the current block by performing a motion search based on the candidate motion vector, performing motion compensation by using the determined motion vector of the current block, and applying local luminance compensation to the current block based on whether the local luminance compensation is to be applied to the current block, wherein a cost function used for performing the motion search is determined based on whether the local luminance compensation is to be applied to the current block.

Abstract: Provided is a method of decoding coefficients included in image data, the method including determining a Rice parameter for a current coefficient, based on a base level of the current coefficient; parsing coefficient level information indicating a size of the current coefficient from a bitstream by using the determined Rice parameter; and identifying the size of the current coefficient by de-binarizing the coefficient level information by using the determined Rice parameter.

Abstract: Disclosed is an image decoding method according to an embodiment, the image decoding method including: obtaining a first reference block and a second reference block, for bi-directional prediction of a current block; obtaining, from a bitstream, weight information for combining the first reference block with the second reference block; performing entropy decoding on the weight information to obtain a weight index; combining the first reference block with the second reference block according to a candidate value indicated by the weight index among candidate values included in a weight candidate group; and reconstructing the current block based on a result of the combining, wherein a first binary value corresponding to the weight index is entropy-decoded based on a context model, and the remaining binary value corresponding to the weight index is entropy-decoded by a bypass method.

Abstract: Provided is a video decoding method including: determining whether or not to perform history-based motion vector prediction for inter-prediction of a current block, based on a location of the current block in a tile including a plurality of largest coding units; when it is determined to perform the history-based motion vector prediction on the current block, generating a motion information candidate list including history-based motion vector candidates; determining a motion vector of the current block by using a motion vector predictor determined from the motion information candidate list; and reconstructing the current block by using the motion vector of the current block, wherein, when a motion constraint is applied to a first tile group, when a reference picture of a first tile from among tiles included in the first tile group is a second picture, a motion vector of the first tile is not permitted to indicate a block of the second picture, the block being located outside a second tile group, and when the m

Abstract: A video decoding method includes obtaining an initial value of a context model for a syntax element, determining, based on the initial value, slope size information, slope sign information, offset size information, and offset sign information of the context model, determining an initial probability of the context model based on the slope size information, the slope sign information, the offset size information, the offset sign information, and a quantization parameter, obtaining at least one bin of a symbol indicating the syntax element by performing context adaptive binary arithmetic coding (CABAC) decoding based on the initial probability of the context model, and reconstructing a video based on the at least one bin.

Abstract: Provided are a video decoding method and apparatus, in which, during video encoding and decoding processes: in which a bit string of a sub-block merge index indicating a candidate motion vector of a sub-block merge mode is obtained from a bitstream, a first bin of a symbol indicating the sub-block merge index is obtained by performing Context Adaptive Binary Arithmetic Coding (CABAC) decoding on the bit string by using a predetermined context model, the other bins of the symbol indicating the sub-block merge index are obtained by performing bypass decoding on the bit string, and prediction with respect to a current block is performed in the sub-block merge mode, based on the first bin and the other bins of the symbol.

Abstract: Provided is an entropy decoding method including: determining a plurality of scaling factors for updating an occurrence probability of a certain binary value for a current encoding symbol; performing arithmetic coding on a binary value of the current encoding symbol, based on the occurrence probability of the certain binary value; and updating the occurrence probability of the certain binary value by using at least one scaling factor of the plurality of scaling factors, according to the binary value of the current encoding symbol.

Abstract: A video decoding method and device for determining whether a prediction mode of a current block is an affine mode; splitting, when the prediction mode of the current block is the affine mode, a luma block of the current block into a plurality of sub luma blocks having a square shape based on a predefined sub block size; determining a mean luma motion vector for four neighboring sub luma blocks among the plurality of sub luma blocks, by using a motion vector of an upper-left sub luma block of the four sub luma blocks and a motion vector of a lower-right sub luma block of the four sub luma blocks; determining the mean luma motion vector to be a motion vector of a current sub chroma block corresponding to the four sub luma blocks; and performing prediction on the current sub chroma block by using the determined motion vector, in a video encoding and decoding process are suggested.

Abstract: Provided is an image decoding method including determining at least one first processing mode for decoding of a current block, based on a motion vector resolution (MVR) of the current block, the at least one first processing mode being from among a plurality of processing modes included in at least one of a prediction process, a transform process, and a filtering process; and decoding the current block, according to the at least one first processing mode.

Abstract: Provided is a video decoding method including: generating a merge candidate list including neighboring blocks referred to to predict a motion vector of a current block in a skip mode or a merge mode; when a merge motion vector difference is used according to merge difference mode information indicating whether the merge motion vector difference and a motion vector determined from the merge candidate list are used, determining a base motion vector from a candidate determined among the merge candidate list based on merge candidate information; determining the motion vector of the current block by using the base motion vector and a merge motion vector difference of the current block, the merge motion vector difference being determined by using a distance index and direction index of the merge motion vector difference of the current block; and reconstructing the current block by using the motion vector of the current block.

Abstract: A method of decoding an image according to an embodiment includes: when a size of a current block in the image is equal to or greater than a certain size, determining a candidate list including, as a candidate, a first reference block indicated by a temporal motion vector; when the first reference block is selected from among candidates included in the candidate list, determining motion vectors of sub-blocks in the current block by using motion vectors obtained from the first reference block; and reconstructing the current block based on sample values of a second reference block indicated by the motion vectors of the sub-blocks.

Abstract: A video decoding method includes predicting a current block according to an intra prediction mode of the current block, determining whether to apply position dependent intra prediction filtering to the current block according to the intra prediction mode of the current block, when the position dependent intra prediction filtering is applied to the current block, determining at least one of an upper reference sample, a left reference sample, an upper weight, and a left weight for the position dependent intra prediction filtering of a current sample of the current block according to the intra prediction mode of the current block, and applying the position dependent intra prediction filtering to the current sample of the current block according to at least one of the upper reference sample, the left reference sample, the upper weight, and the left weight.

Abstract: Video decoding includes obtaining intra prediction mode information for a current block; determining an intra prediction direction indicated by the intra prediction mode, and a shape of the current block; predicting the current block by intra predicting the current block; and reconstructing the current block, according to a prediction result with respect to the current block. The intra prediction direction of the current block is used and may include: when the current block has the square shape, determining the intra prediction direction of the current block in a prediction direction indicated by the intra prediction mode information; and when the current block has the non-square shape, determining the intra prediction direction of the current block based on a result of comparison between a reference prediction direction and the prediction direction, the reference prediction direction being determined according to a ratio of the width and the height of the current block.

Abstract: Provided is a video decoding method including: generating coding units by splitting at least one of a height and a width of a largest coding unit having a first size; based on whether a height or a width of a non-square first coding unit including an outer boundary of an image, among the coding units, is greater than a maximum transform size, determining whether it is allowed to generate two second coding units by splitting at least one of the height and the width of the first coding unit; and decoding the second coding units generated from the first coding unit.