Abstract: Provided are a method and apparatus for encoding or decoding a 360-degree image. An image decoding method and apparatus according to an embodiment include: obtaining image data from a bitstream; decoding a first region of a projection image corresponding to a non-clipping region of a 360-degree image from the image data; obtaining information about a clipping region of the 360-degree image from the bitstream; determining a second region of the projection image, based on the information about the clipping region; and converting the projection image including the first region and the second region into the 360-degree image.

Abstract: Provided are a method and apparatus for encoding or decoding a 360-degree image. According to an image decoding method and apparatus according to an embodiment, an original 360-degree image is reconstructed by acquiring image data from a bitstream, decoding a projection image of a 360-degree image from the image data, converting the projection image into the 360-degree image, acquiring rotation information of the 360-degree image from the bitstream, and rotating the 360-degree image based on the rotation information.

Abstract: Provided is a video decoding apparatus including an encoding information obtainer configured to obtain, from a bitstream, reference layer size information, reference layer offset information, current layer size information, and current layer offset information, a scale ratio determiner configured to determine a scale ratio indicating a difference between a size of a reference area and a size of an expanded reference area, according to the size of the reference area which is determined from the reference layer size information and the reference layer offset information and the size of the expanded reference area which is determined from the current layer size information and the current layer offset information, and an up-sampling unit configured to determine the expanded reference area by up-sampling the reference area according to the reference layer offset information, the current layer offset information, and the scale ratio.

Abstract: A method for decoding an image including performing intra prediction on a chrominance block according to whether the intra prediction mode of the chrominance block is equal to an intra prediction mode of a luminance block.

Abstract: A probably update method used in context-based adaptive binary arithmetic coding (CABAC) is disclosed. The probably update method for binary arithmetic decoding obtains an autocorrelation value of each bin by using values of received bins, determines at least one scaling factor used to update a probability of a binary value based on the autocorrelation value, and updates a probability used in context-based adaptive binary arithmetic decoding by using the determined at least one scaling factor.

Abstract: A video decoding apparatus includes: a splitter configured to split an image into at least one block; a predictor configured to predict a current sample by using at least one of a value obtained by applying a first weight to a first sample predicted earlier than the current sample in a current block and being adjacent to the current sample in a horizontal direction and a value obtained by applying a first weight to a second sample predicted earlier than the current sample in the current block and being adjacent to the current sample in a vertical direction; and a decoder configured to decode the image by using a residual value of the current sample obtained from a bitstream and a prediction value of the current sample.

Abstract: The present disclosure relates to signaling of sample adaptive offset (SAO) parameters determined to minimize an error between an original image and a reconstructed image in video encoding and decoding operations. An SAO decoding method includes obtaining context-encoded leftward SAO merge information and context-encoded upward SAO merge information from a bitstream of a largest coding unit (MCU); obtaining SAO on/off information context-encoded with respect to each color component, from the bitstream; if the SAO on/off information indicates to perform SAO operation, obtaining absolute offset value information for each SAO category bypass-encoded with respect to each color component, from the bitstream; and obtaining one of band position information and edge class information bypass-encoded with respect to each color component, from the bitstream.

Abstract: The present disclosure relates to signaling of sample adaptive offset (SAO) parameters determined to minimize an error between an original image and a reconstructed image in video encoding and decoding operations. An SAO decoding method includes obtaining context-encoded leftward SAO merge information and context-encoded upward SAO merge information from a bitstream of a largest coding unit (MCU); obtaining SAO on/off information context-encoded with respect to each color component, from the bitstream; if the SAO on/off information indicates to perform SAO operation, obtaining absolute offset value information for each SAO category bypass-encoded with respect to each color component, from the bitstream; and obtaining one of band position information and edge class information bypass-encoded with respect to each color component, from the bitstream.

Abstract: Provided is an image encoding method including determining at least one sample value related to a first block, based on sample values of previously-reconstructed reference samples; determining at least one pattern in which samples of the first block are to be arranged; generating one or more candidate prediction blocks for the first block, based on the at least one sample value and the at least one pattern; and determining prediction values of the samples of the first block, based on one of the one or more candidate prediction blocks.

Abstract: Provided is a video decoding method including: acquiring offset type information of a current block; determining a neighboring sample of a current reconstruction sample of the current block according to an edge direction when the offset type information of the current block indicates an edge type; determining an offset category of the current reconstruction sample based on a sample value gradient between a sample value of the current reconstruction sample and a sample value of the neighboring sample and a difference in the sample value gradient; and applying, from among offsets acquired from a bitstream, an offset according to the determined offset category to the current reconstruction sample.

Abstract: A method of encoding a video is provided, the method includes: determining a filtering boundary on which deblocking filtering is to be performed based on at least one data unit from among a plurality of coding units that are hierarchically configured according to depths indicating a number of times at least one maximum coding unit is spatially spilt, and a plurality of prediction units and a plurality of transformation units respectively for prediction and transformation of the plurality of coding units, determining filtering strength at the filtering boundary based on a prediction mode of a coding unit to which pixels adjacent to the filtering belong from among the plurality of coding units, and transformation coefficient values of the pixels adjacent to the filtering boundary, and performing deblocking filtering on the filtering boundary based on the determined filtering strength.

Abstract: The present disclosure relates to signaling of sample adaptive offset (SAO) parameters determined to minimize an error between an original image and a reconstructed image in video encoding and decoding operations. An SAO decoding method includes obtaining context-encoded leftward SAO merge information and context-encoded upward SAO merge information from a bitstream of a largest coding unit (MCU); obtaining SAO on/off information context-encoded with respect to each color component, from the bitstream; if the SAO on/off information indicates to perform SAO operation, obtaining absolute offset value information for each SAO category bypass-encoded with respect to each color component, from the bitstream; and obtaining one of band position information and edge class information bypass-encoded with respect to each color component, from the bitstream.

Abstract: A video encoding method including determining a phase shift between pixels of an enhancement layer image and a reference layer image, according to a scaling factor between the enhancement layer image and the reference layer image and a color format of the enhancement layer; selecting at least one filter coefficient set corresponding to the phase shift, from filter coefficient data including filter coefficient sets; generating an up-sampled reference layer image by extending a resolution of the reference layer image according to the scaling factor by performing interpolation filtering on the reference layer image by using the filter coefficient set; obtaining a prediction error between the up-sampled reference layer image and the enhancement layer image; generating an enhancement layer bitstream including the prediction error and a scalable codec; and generating a base layer bitstream by encoding the base layer images.

Abstract: Provided is a video decoding method including: obtaining motion prediction mode information regarding a current block in a current picture; when a bi-directional motion prediction mode is indicated, obtaining a first motion vector and a second motion vector indicating a first reference block and a second reference block of the current block in a first reference picture and second reference picture, respectively; generating a pixel value of a first pixel of the first reference block indicated by the first motion vector and a pixel value of a second pixel of the second reference block indicated by the second motion vector by applying an interpolation filter to a first neighboring region of the first pixel and a second neighboring region of the second pixel; generating gradient values of the first pixel and the second pixel by applying a filter to the first neighboring region and the second neighboring region; and generating a prediction pixel value of the current block by using the pixel values and the gradient

Abstract: A video encoding method and apparatus, and a video decoding method and apparatus for generating a reconstructed image having a minimized error between an original image and the reconstructed image. The video decoding method accompanied by a sample adaptive offset (SAO) adjustment, the method includes: obtaining 5 slice SAO parameters with respect to a current slice from a slice header of a received bitstream; obtaining luma SAO use information for a luma component of the current slice and chroma SAO use information for chroma components thereof from among the slice SAO parameters; determining whether to perform a SAO operation on the luma component of 10 the current slice based on the obtained luma SAO use information; and equally determining whether to perform the SAO adjustment on a first chroma component and a second chroma component of the current slice based on the obtained chroma SAO use information.

Abstract: Disclosed are a video encoding method and apparatus and a video decoding method and apparatus. The method of encoding video includes: producing a first predicted coding unit of a current coding unit, which is to be encoded; determining whether the current coding unit comprises a portion located outside a boundary of a current picture; and producing a second predicted coding unit is produced by changing a value of pixels of the first predicted coding unit by using the pixels of the first predicted coding unit and neighboring pixels of the pixels when the current coding unit does not include a portion located outside a boundary of the current picture. Accordingly, a residual block that is the difference between the current encoding unit and the second predicted encoding unit, can be encoded, thereby improving video prediction efficiency.

Abstract: Disclosed are a video encoding method and apparatus and a video decoding method and apparatus. The method of encoding video includes: producing a first predicted coding unit of a current coding unit, which is to be encoded; determining whether the current coding unit comprises a portion located outside a boundary of a current picture; and producing a second predicted coding unit is produced by changing a value of pixels of the first predicted coding unit by using the pixels of the first predicted coding unit and neighboring pixels of the pixels when the current coding unit does not include a portion located outside a boundary of the current picture. Accordingly, a residual block that is the difference between the current encoding unit and the second predicted encoding unit, can be encoded, thereby improving video prediction efficiency.

Abstract: Disclosed are a video encoding method and apparatus and a video decoding method and apparatus. The method of encoding video includes: producing a first predicted coding unit of a current coding unit, which is to be encoded; determining whether the current coding unit comprises a portion located outside a boundary of a current picture; and producing a second predicted coding unit is produced by changing a value of pixels of the first predicted coding unit by using the pixels of the first predicted coding unit and neighboring pixels of the pixels when the current coding unit does not include a portion located outside a boundary of the current picture. Accordingly, a residual block that is the difference between the current encoding unit and the second predicted encoding unit, can be encoded, thereby improving video prediction efficiency.

Abstract: Disclosed are a video encoding method and apparatus and a video decoding method and apparatus. The method of encoding video includes: producing a first predicted coding unit of a current coding unit, which is to be encoded; determining whether the current coding unit comprises a portion located outside a boundary of a current picture; and producing a second predicted coding unit is produced by changing a value of pixels of the first predicted coding unit by using the pixels of the first predicted coding unit and neighboring pixels of the pixels when the current coding unit does not include a portion located outside a boundary of the current picture. Accordingly, a residual block that is the difference between the current encoding unit and the second predicted encoding unit, can be encoded, thereby improving video prediction efficiency.

Abstract: Disclosed are a video encoding method and apparatus and a video decoding method and apparatus. The method of encoding video includes: producing a first predicted coding unit of a current coding unit, which is to be encoded; determining whether the current coding unit comprises a portion located outside a boundary of a current picture; and producing a second predicted coding unit is produced by changing a value of pixels of the first predicted coding unit by using the pixels of the first predicted coding unit and neighboring pixels of the pixels when the current coding unit does not include a portion located outside a boundary of the current picture. Accordingly, a residual block that is the difference between the current encoding unit and the second predicted encoding unit, can be encoded, thereby improving video prediction efficiency.