Systems and methods are described for reducing the complexity of using bi-directional optical flow (BIO) in video coding. In some embodiments, bit-width reduction steps are introduced in the BIO motion refinement process to reduce the maximum bit-width used for BIO calculations. In some embodiments, simplified interpolation filters are used to generate predicted samples in an extended region around a current coding unit. In some embodiments, different interpolation filters are used for vertical versus horizontal interpolation. In some embodiments, BIO is disabled for coding units with small heights and/or for coding units that are predicted using a sub-block level inter prediction technique, such as advanced temporal motion vector prediction (ATMVP) or affine prediction.

Systems and methods are described for reducing the complexity of using bi-directional optical flow (BIO) in video coding. In some embodiments, bit-width reduction steps are introduced in the BIO motion refinement process to reduce the maximum bit-width used for BIO calculations. In some embodiments, simplified interpolation filters are used to generate predicted samples in an extended region around a current coding unit. In some embodiments, different interpolation filters are used for vertical versus horizontal interpolation. In some embodiments, BIO is disabled for coding units with small heights and/or for coding units that are predicted using a sub-block level inter prediction technique, such as advanced temporal motion vector prediction (ATMVP) or affine prediction.

Flag information associated with the current block is obtained in coded information, which indicates whether the current block is intra predicted based at least in part on an intra mode derivation. In response to the flag information being true, a plurality of candidate intra modes is determined based on neighboring samples of the current block. A first intra mode of the current block is determined based on a first syntax element that is included in the coded information. The first syntax element indicates the first intra mode of the current block from a most probable mode (MPM) list and a MPM remainder. A second intra mode of the current block is determined based on the first intra mode and the plurality of candidate intra modes. The current block is reconstructed based on the first intra mode and the second intra mode.

Flag information associated with the current block is obtained in coded information, which indicates whether the current block is intra predicted based at least in part on an intra mode derivation. In response to the flag information being true, a plurality of candidate intra modes is determined based on neighboring samples of the current block. A first intra mode of the current block is determined based on a first syntax element that is included in the coded information. The first syntax element indicates the first intra mode of the current block from a most probable mode (MPM) list and a MPM remainder. A second intra mode of the current block is determined based on the first intra mode and the plurality of candidate intra modes. The current block is reconstructed based on the first intra mode and the second intra mode.

An image decoding method performed by a decoding device according to the present disclosure comprises the steps of: obtaining prediction-related information and indication information comprising a first flag which indicates whether or not a sample adaptive offset (SAO) process to be applied to a current block is applied at a picture level or a slice level; parsing information related to the SAO process from a picture header or a slice header on the basis of the first flag; generating prediction samples for the current block on the basis of the prediction-related information; generating reconstructed samples for the current block on the basis of the prediction samples; and performing the SAO process for the reconstructed samples on the basis of the information related to the SAO process.

Devices and methods of intra prediction of a block of a picture are provided. In various embodiments, information indicating an Intra Sub-Partitions (ISP) split type can be obtained. A value of a filter flag can be set based on the ISP split type. For instance, the value of the filter flag can be set to 0 when the ISP split type does not indicate not to split a current block. A set of coefficients of an interpolation filter can then be selected according to the value of the filter flag. For instance, fG coefficients or fC coefficients can be selected based on the value of the filter flag. Still in those embodiment, the selected set of coefficients can be applied to reference samples. In some embodiments, the method removes mode dependency during selection of interpolation filter type. This could increase encoding or decoding efficiency.

Devices and methods of intra prediction of a block of a picture are provided. In various embodiments, information indicating an Intra Sub-Partitions (ISP) split type can be obtained. A value of a filter flag can be set based on the ISP split type. For instance, the value of the filter flag can be set to 0 when the ISP split type does not indicate not to split a current block. A set of coefficients of an interpolation filter can then be selected according to the value of the filter flag. For instance, fG coefficients or fC coefficients can be selected based on the value of the filter flag. Still in those embodiment, the selected set of coefficients can be applied to reference samples. In some embodiments, the method removes mode dependency during selection of interpolation filter type. This could increase encoding or decoding efficiency.

A method for intra prediction of a video block, comprising: padding of luminance reference samples rows for a chroma component of a current block vertically aligned with a largest coding unit (LCU) boundary; applying a filter F to reconstructed luma samples of a luma component of the current block and to luma samples in selected position neighboring to the current block, to obtain filtered reconstructed luma samples, wherein a shape of the F is same for blocks in the LCU; obtaining linear model coefficients, based on the filtered reconstructed luma samples; and performing cross-component prediction based on the obtained linear model coefficients and the filtered reconstructed luma samples of the current block, to obtain a prediction value of the chroma component of the current block.

A method for intra prediction of a video block, comprising: padding of luminance reference samples rows for a chroma component of a current block vertically aligned with a largest coding unit (LCU) boundary; applying a filter F to reconstructed luma samples of a luma component of the current block and to luma samples in selected position neighboring to the current block, to obtain filtered reconstructed luma samples, wherein a shape of the F is same for blocks in the LCU; obtaining linear model coefficients, based on the filtered reconstructed luma samples; and performing cross-component prediction based on the obtained linear model coefficients and the filtered reconstructed luma samples of the current block, to obtain a prediction value of the chroma component of the current block.

A method for decoding a data stream representative of an image split into blocks. For a current block of the image, an item of information indicating a coding mode among a first and a second coding mode of the current block is decoded from the data stream and the current block is decoded depending on this information. When the coding mode of the current block corresponds to the second coding mode, the current block is reconstructed from a prediction obtained, for each pixel, from another previously decoded pixel belonging to the current block or to a previously decoded block of the image, and from a decoded residue associated with the pixel. At least one processing method is applied to the reconstructed current block for at least one pixel of the current block depending on the coding mode of the current block and/or the coding mode of the neighbouring blocks.