Abstract: A method and apparatus for performing transformation and inverse transformation on a current block by using multi-core transform kernels in video encoding and decoding processes. A video decoding method may include obtaining, from a bitstream, multi-core transformation information indicating whether multi-core transformation kernels are to be used according to a size of a current block; obtaining horizontal transform kernel information and vertical transform kernel information from the bitstream when the multi-core transformation kernels are used according to the multi-core transformation information; determining a horizontal transform kernel for the current block according to the horizontal transform kernel information; determining a vertical transform kernel for the current block according to the vertical transform kernel information; and performing inverse transformation on the current block by using the horizontal transform kernel and the vertical transform kernel.

Abstract: Provided is a video decoding method including determining a displacement vector per unit time of pixels of a current block in a horizontal direction or a vertical direction, the pixels including a pixel adjacent to an inside of a boundary of the current block, by using values about reference pixels included in a first reference block and a second reference block, without using a stored value about a pixel located outside boundaries of the first reference block and the second reference block; and obtaining a prediction block of the current block by performing block-unit motion compensation and pixel group unit motion compensation on the current block by using a gradient value in the horizontal direction or the vertical direction of a first corresponding reference pixel in the first reference block which corresponds to a current pixel included in a current pixel group in the current block, a gradient value in the horizontal direction or the vertical direction of a second corresponding reference pixel in the sec

Abstract: Provided is a video decoding method including: obtaining a first motion vector indicating a first reference block of a current block in a first reference picture and a second motion vector indicating a second reference block of the current block in a second reference picture; obtaining a parameter related to pixel group unit motion compensation of the current block, based on at least one of information of the parameter related to the pixel group unit motion compensation and a parameter related to an image including the current picture; generating a prediction block by performing, with respect to the current block, block unit motion compensation based on the first motion vector and the second motion vector and performing the pixel group unit motion compensation based on the parameter related to the pixel group unit motion compensation; and reconstructing the current block. Here, a pixel group may include at least one pixel.

Abstract: An image decoding method and apparatus according to an embodiment may extract, from a bitstream, a quantization coefficient generated through core transformation, secondary transformation, and quantization; generate an inverse-quantization coefficient by performing inverse quantization on the quantization coefficient; generate a secondary inverse-transformation coefficient by performing secondary inverse-transformation on a low frequency component of the inverse-quantization coefficient, the secondary inverse-transformation corresponding to the secondary transformation; and perform core inverse-transformation on the secondary inverse-transformation coefficient, the core inverse-transformation corresponding to the core transformation.

Abstract: Provided is a video decoding method including: obtaining, from a bitstream, prediction motion vector information indicating a prediction motion vector of a current block and difference motion vector information indicating a difference motion vector of the current block; determining the prediction motion vector of the current block according to whether or not an adjacent block of the current block is decoded and the prediction motion vector information; determining a motion vector resolution of the current block according to whether or not the adjacent block of the current block is decoded; determining the difference motion vector of the current block according to the difference motion vector information; determining a motion vector of the current block according to the prediction motion vector, the motion vector resolution, and the difference motion vector; and reconstructing the current block according to the motion vector of the current block, wherein the adjacent block of the current block includes a right

Abstract: Provided is a method of decoding a video according to an embodiment, the method including determining at least one processing block for splitting the video; determining an order of determining at least one largest coding unit in the at least one processing block; determining at least one largest coding unit on the basis of the determined order; and decoding the determined at least one largest coding unit, wherein the order is one of a plurality of orders for determining a largest coding unit.

Abstract: Provided is a video decoding method including: obtaining, from a bitstream, prediction motion vector information indicating a prediction motion vector of a current block and difference motion vector information indicating a difference motion vector of the current block; determining the prediction motion vector of the current block according to whether or not an adjacent block of the current block is decoded and the prediction motion vector information; determining a motion vector resolution of the current block according to whether or not the adjacent block of the current block is decoded; determining the difference motion vector of the current block according to the difference motion vector information; determining a motion vector of the current block according to the prediction motion vector, the motion vector resolution, and the difference motion vector; and reconstructing the current block according to the motion vector of the current block, wherein the adjacent block of the current block includes a right

Abstract: Provided is a method of decoding a video according to an embodiment, the method including determining at least one processing block for splitting the video; determining an order of determining at least one largest coding unit in the at least one processing block; determining at least one largest coding unit on the basis of the determined order; and decoding the determined at least one largest coding unit, wherein the order is one of a plurality of orders for determining a largest coding unit.

Abstract: Provided is a method of decoding a video according to an embodiment, the method including determining at least one processing block for splitting the video; determining an order of determining at least one largest coding unit in the at least one processing block; determining at least one largest coding unit on the basis of the determined order; and decoding the determined at least one largest coding unit, wherein the order is one of a plurality of orders for determining a largest coding unit.

Abstract: Provided is a video decoding method including: obtaining correlation information of a luma value and a chroma value from a most probable chroma (MPC) mode reference region of a current chroma block; determining a prediction value of a chroma sample of the current chroma block from luma samples of a current luma block corresponding to the current chroma block, according to the correlation information; and decoding the current chroma block based on the prediction value of the chroma sample.

Abstract: A video decoding and video encoding method of performing inter prediction in a bi-directional motion prediction mode, in which a prediction pixel value of a current block may be generated by not only using a pixel value of a first reference block of a first reference picture and a pixel value of a second reference block of a second reference picture, but also using a first gradient value of the first reference block and a second gradient value of the second reference block, in a bi-directional motion prediction mode. Accordingly, encoding and decoding efficiency may be increased since a prediction block similar to an original block may be generated.

Abstract: Provided are a method and apparatus for performing transformation and inverse transformation on a chroma block by using a variable transform kernel, during video encoding and decoding processes. A video decoding method includes: obtaining, from a bitstream, chroma multi-transform kernel information indicating whether a chroma transform kernel for inverse transformation of a chroma block is determined to be among a plurality of chroma transform kernels; while determining whether the chroma transform kernel is determined to be among the plurality of chroma transform kernels according to the chroma multi-transform kernel information, determining whether to determine the chroma transform kernel by using a luma transform kernel; and performing inverse transformation on the chroma block by using the chroma transform kernel.

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. 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: Accordingly embodiments herein disclose a method for producing 360 degree image content on a rectangular projection. The method includes detecting whether at least one discontinuous boundary is present in the 360-degree image content, wherein the at least one discontinuous boundary is detected using the packing of one or more projection segments. Further, the method includes obtaining one or more reconstructed blocks from the 360-degree image content. The reconstructed blocks are generated from the 360 degree image content. Further, the method includes performing one of enabling at least one in-loop filtering function on the one or more reconstructed blocks of the 360 degree image content when the at least one of image content discontinuous boundary is not present and disabling at least one in-loop filtering function on the one or more reconstructed blocks of the 360 degree image content located around the at least one discontinuous boundary.

Abstract: Accordingly embodiments herein disclose a method for producing 360 degree image content on a rectangular projection. The method includes detecting whether at least one discontinuous boundary is present in the 360-degree image content, wherein the at least one discontinuous boundary is detected using the packing of one or more projection segments. Further, the method includes obtaining one or more reconstructed blocks from the 360-degree image content. The reconstructed blocks are generated from the 360 degree image content. Further, the method includes performing one of enabling at least one in-loop filtering function on the one or more reconstructed blocks of the 360 degree image content when the at least one of image content discontinuous boundary is not present and disabling at least one in-loop filtering function on the one or more reconstructed blocks of the 360 degree image content located around the at least one discontinuous boundary.

Abstract: A video decoding and video encoding method of performing inter prediction in a bi-directional motion prediction mode, in which a prediction pixel value of a current block may be generated by not only using a pixel value of a first reference block of a first reference picture and a pixel value of a second reference block of a second reference picture, but also using a first gradient value of the first reference block and a second gradient value of the second reference block, in a bi-directional motion prediction mode. Accordingly, encoding and decoding efficiency may be increased since a prediction block similar to an original block may be generated.

Abstract: Provided is a video decoding method including determining a displacement vector per unit time of pixels of a current block in a horizontal direction or a vertical direction, the pixels including a pixel adjacent to an inside of a boundary of the current block, by using values about reference pixels included in a first reference block and a second reference block, without using a stored value about a pixel located outside boundaries of the first reference block and the second reference block; and obtaining a prediction block of the current block by performing block-unit motion compensation and pixel group unit motion compensation on the current block by using a gradient value in the horizontal direction or the vertical direction of a first corresponding reference pixel in the first reference block which corresponds to a current pixel included in a current pixel group in the current block, a gradient value in the horizontal direction or the vertical direction of a second corresponding reference pixel in the sec

Abstract: Provided is a video decoding method including: obtaining correlation information of a luma value and a chroma value from a most probable chroma (MPC) mode reference region of a current chroma block; determining a prediction value of a chroma sample of the current chroma block from luma samples of a current luma block corresponding to the current chroma block, according to the correlation information; and decoding the current chroma block based on the prediction value of the chroma sample.

Abstract: Provided is a video decoding method including: obtaining a first motion vector indicating a first reference block of a current block in a first reference picture and a second motion vector indicating a second reference block of the current block in a second reference picture; obtaining a parameter related to pixel group unit motion compensation of the current block, based on at least one of information of the parameter related to the pixel group unit motion compensation and a parameter related to an image including the current picture; generating a prediction block by performing, with respect to the current block, block unit motion compensation based on the first motion vector and the second motion vector and performing the pixel group unit motion compensation based on the parameter related to the pixel group unit motion compensation; and reconstructing the current block. Here, a pixel group may include at least one pixel.