Abstract: According to the present disclosure, ALF parameters and/or LMCS parameters can be hierarchically signaled, which enables a reduction in the amount of data to be signaled for video/image coding and an increase in the coding efficiency.

Abstract: Embodiments of the disclosure provide methods and devices for decoding video signals using inter prediction. According to an embodiment of the disclosure, a method for processing a video signal comprises constructing a reference picture list of a current picture in the video signal and performing a prediction for a current picture by using the reference picture list, wherein constructing the reference picture list comprising, if a first entry of the reference picture list corresponds to a short-term reference picture (STRP), obtaining a picture order count (POC) difference between a picture related to the first entry and another picture, and if a second entry of the reference picture list corresponds to a long-term reference picture (LTRP), obtaining a POC modulo value of a picture related to the second entry. A reference picture list for identifying a picture may be generated in a simplified and effective manner. Thus, the compression performance may be increased, and the computation time may be decreased.

Abstract: Provided is an image encoding/decoding method and apparatus. The image decoding method comprises obtaining subpicture information from a bitstream, deriving one or more subpictures in a current picture based on the subpicture information, and decoding a current subpicture in the current picture based on the subpicture information. The subpicture information may comprise a first flag specifying whether each of the one or more subpictures is treated as a picture, and, based on the bitstream including at least one first layer referring to a current layer including the current picture, the first flag for the first subpicture included in a first layer and corresponding to the current subpicture, and the first flag for the current subpicture have the same value.

Abstract: An image decoding method performed by a decoding apparatus according to the present document comprises the steps of: obtaining a flag indicating whether quantization parameter data for combined chroma coding is present on the basis of a type of chroma; obtaining the quantization parameter data for the combined chroma coding on the basis of the flag; deriving a chroma quantization parameter table on the basis of the quantization parameter data; deriving a quantization parameter for the combined chroma coding on the basis of the chroma quantization parameter table; deriving residual samples on the basis of the quantization parameter; and generating a reconstructed picture on the basis of the residual samples.

Abstract: Disclosed herein are an image encoding/decoding method and apparatus. An image decoding method performed by an image encoding apparatus may include acquiring size information indicating a size of a current slice corresponding to at least a portion of a current picture from a bitstream and determining the size of the current slice based on the size information.

Abstract: According to embodiments of the present document, information for carrying out in-loop filtering across virtual boundaries can be efficiently signaled. For example, in-loop filtering can be carried out on the basis of signaling of information which is related to whether in-loop filtering across virtual boundaries is enabled or not.

Abstract: According to the disclosure of the present disclosure, the index of an alternative filter is derived from ALF information, and an ALF procedure for a chroma component of a current block can be performed on the basis of the alternative filter

Abstract: A video decoding method performed by a video decoding device according to the present document comprises the steps of: parsing a flag pertaining to a weighted prediction from a bitstream; parsing the syntax of a prediction weighted table from the bitstream based on the flag; performing a weighted prediction for the current block in the current picture based on the prediction weighted table syntax to generate prediction samples for the current block; generating residual samples based on residual information acquired from the bitstream; and generating reconstructed samples for the current block based on the prediction samples and the residual samples, wherein the prediction weighted table syntax can be parsed from the picture header of the bitstream based on the value of the flag being 1, and can be parsed from the slice header of the bitstream based on the value of the flag being 0.

Abstract: An image encoding/decoding method and device are provided. An image decoding method performed by an image decoding device according to the present disclosure may comprise the steps of: determining a prediction mode of the current block on the basis of prediction information obtained from a bitstream; on the basis of the prediction mode of the current block, obtaining a flag indicating whether a color space transform is applied to a residual sample of the current block; determining a quantization parameter of the current block on the basis of the flag; and determining a transform coefficient of the current block on the basis of the quantization parameter.

Abstract: According to embodiments of the present document, the subjective/objective quality of an image can be improved through image coding on the basis of subpictures and/or virtual boundaries, and consumption of hardware resources required for coding can be reduced.

Abstract: An image encoding/decoding method and apparatus are provided. An image decoding method performed by an image decoding apparatus may comprise parsing weight information specifying a weight for a reference sample from a bitstream according to a weight parameter syntax structure, and decoding a current block by performing inter prediction based on the weight information. The parsing according to the weight parameter syntax structure may comprise obtaining weight number information specifying the number of weight information obtained from the bitstream according to the weight parameter syntax structure and obtaining weight information from the weight parameter syntax structure based on the weight number information.

Abstract: A video decoding method performed by a video decoding apparatus according to the present document may comprise the steps of: parsing a prediction weighted table syntax from a bitstream; parsing number information about weighted reference pictures in a reference picture list from the prediction weighted table syntax; deriving a weighting factor-related flag about the reference picture list on the basis of the number information; performing weighted prediction on a current block on the basis of the weighting factor-related flag so as to derive prediction samples of the current block; generating residual samples on the basis of residual information obtained from the bitstream; and reconstructing a current picture on the basis of the prediction samples and the residual samples, wherein the prediction weighted table syntax is parsed from a picture header of the bitstream.

Abstract: According to embodiments described herein, sub-pictures and/or virtual boundaries can be used for coding an image. For example, sub-pictures in the current picture can be used for predicting, reconstructing, and/or filtering the current picture. Virtual boundaries can be used for filtering reconstructed samples of the current picture. Through image coding based on the subpictures and/or virtual boundaries according to embodiments described herein, the subjective/objective quality of an image can be improved, and the consumption of hardware resources necessary for the coding can be reduced.

Abstract: A video decoding method performed by a video decoding apparatus, according to the present document, comprises the steps of: parsing a flag for weighted prediction from a bitstream; parsing a prediction weighted table syntax from the bitstream on the basis of the flag; generating prediction samples by performing weighted prediction on a current block within a current picture on the basis of the prediction weighted table syntax; and generating reconstructed samples for the current block on the basis of the prediction samples, wherein the prediction weighted table syntax may be parsed from a picture header or slice header of the bitstream on the basis of a value of the flag.

Abstract: According to an image coding method according to embodiments of the present document, information related to in-loop filtering may be efficiently signaled, and repetitive procedures for signaling subpicture-related information may be reduced.

Abstract: A video decoding method performed by a video decoding device according to this document comprises the steps of: parsing prediction weighted table syntax from a bitstream; parsing information on the number of reference pictures in a reference picture list from the prediction weighted table syntax; deriving weights for weighted prediction on the basis of the information on the number of reference pictures; deriving prediction samples of a current block by performing weighted prediction for the current block on the basis of the weights; and reconstructing a current picture on the basis of the prediction samples, wherein the prediction weighted table syntax may be parsed from a picture header of the bitstream.

Abstract: A video decoding method performed by a video decoding device according to the present document may comprise the steps of: acquiring image information from a bitstream, the image information including a picture header associated with the current picture including a plurality of slices; parsing, from the picture header, at least one of a first flag indicating whether information necessary for an inter-prediction operation for a decoding process is present in the picture header, or a second flag indicating whether information necessary for an intra-prediction operation for the decoding process is present in the picture header; generating prediction samples by performing at least one of intra-prediction or inter-prediction for the slices in the current picture on the basis of at least one of the first flag or the second flag; and generating reconstructed samples on the basis of the prediction samples.

Abstract: According to the disclosure of the present document, a decoded picture buffer (DPB) may be updated on the basis of DPB-related information. The DPB-related information may include a syntax element related to a maximum required size of the DPB. In updating the DPB, a bumping process may be invoked on the basis of a case where a first condition, in which the number of pictures in the DPB is neither greater than nor equal to a value obtained by adding 1 to a value of the syntax element related to the maximum required size of the DPB, is satisfied.

Abstract: A method for decoding an image by a decoding device according to the present invention comprises the steps of: deriving, from a bit stream, transform coefficients of a block to be decoded; deriving residual samples of the block to be decoded, on the basis of a selective transform of the transform coefficients; and generating a reconstructed picture on the basis of the residual samples of the block to be decoded and prediction samples of the block to be decoded, wherein the selective transform is performed on the basis of a modified transform matrix, the modified transform matrix comprises a matrix including a modified basis vector, and the modified basis vector contains a certain number of elements selected from N elements.

Abstract: A video decoding method executed by a video decoding apparatus according to the present document comprises the steps of: parsing a flag associated with weighted prediction from a bitstream; on the basis of the flag, parsing a prediction weighted table syntax from the bitstream; and on the basis of the prediction weighted table syntax, executing a weighted prediction on a current block in a current picture to reconstruct the current picture, wherein on the basis of the value of the flag being 1, the prediction weighted table syntax may be parsed from a picture header of the bitstream, and on the basis of the value of the flag being 0, the prediction weighted table syntax may be parsed from a slice header of the bitstream.