There is provided a method and apparatus of encoding/decoding an intra prediction mode. The method comprises deriving an intra prediction mode with respect to a current block, constructing a reference sample for the current block on the basis of the derived intra prediction mode, and performing the intra prediction with respect to the current block using the derived intra prediction mode and the constructed reference sample, wherein the intra prediction mode is derived on the basis of a most probable mode (MPM).

There is provided a method and apparatus of encoding/decoding an intra prediction mode. The method comprises deriving an intra prediction mode with respect to a current block, constructing a reference sample for the current block on the basis of the derived intra prediction mode, and performing the intra prediction with respect to the current block using the derived intra prediction mode and the constructed reference sample, wherein the intra prediction mode is derived on the basis of a most probable mode (MPM).

A video decoding method according to the present invention may comprise: a step for determining whether to divide a current block into a plurality of sub-blocks; a step for determining an intra prediction mode for the current block; and a step for performing intra prediction for each sub-block on the basis of the intra prediction mode, when the current block is divided into the plurality of sub-blocks.

Methods, systems, apparatuses for video processing are described. A method for processing video includes performing a conversion between a video and a bitstream of the video according to a format rule, and wherein the format rule specifies to include, in a general constraint syntax structure associated with the video, one or more general constraint flags indicating whether corresponding syntax elements are included in a sequence parameter set (SPS) and/or a picture parameter set (PPS) and/or a picture header (PH) and/or a slice header (SH) or to constrain values of the syntax elements in the SPS and/or the PPS and/or the PH and/or the SH.

An encoder includes circuitry and memory connected to the circuitry. In operation, the circuitry: derives a correction parameter using only a neighboring reconstructed image that neighbors a processing unit which has a determined size and is located at an upper left of a current block to be processed in an image, among neighboring reconstructed images that neighbor the current block, and performs correction processing of the current block based on the correction parameter derived, when the current block has a size larger than the determined size.

An encoder includes circuitry and memory connected to the circuitry. In operation, the circuitry: derives a correction parameter using only a neighboring reconstructed image that neighbors a processing unit which has a determined size and is located at an upper left of a current block to be processed in an image, among neighboring reconstructed images that neighbor the current block, and performs correction processing of the current block based on the correction parameter derived, when the current block has a size larger than the determined size.

Aspects of the disclosure provide methods and apparatuses for video encoding/decoding. In some examples, an apparatus for video encoding includes processing circuitry. The processing circuitry determines whether a current block in a current picture is a small block based on a block size threshold. The processing circuitry constructs a motion vector predictor list for the current block based on whether the current block is the small block, at least one redundancy check with a motion vector candidate in the motion vector predictor list being performed in the construction of the motion vector predictor list based on whether the current block is the small block. The processing circuitry encodes the current block based on the constructed motion vector predictor list.

Aspects of the disclosure provide methods and apparatuses for video encoding/decoding. In some examples, an apparatus for video encoding includes processing circuitry. The processing circuitry determines whether a current block in a current picture is a small block based on a block size threshold. The processing circuitry constructs a motion vector predictor list for the current block based on whether the current block is the small block, at least one redundancy check with a motion vector candidate in the motion vector predictor list being performed in the construction of the motion vector predictor list based on whether the current block is the small block. The processing circuitry encodes the current block based on the constructed motion vector predictor list.

An image decoding method according to the present invention includes reconstructing a residual block by inverse-quantizing and inverse-transforming an entropy-decoded residual block, generating a prediction block by performing intra prediction on a current block, and reconstructing an picture by adding the reconstructed residual block to the prediction block, wherein generating the prediction block includes generating a final prediction value of a prediction target pixel included in the current block based on a first prediction value of the prediction target pixel and a final correction value calculated by performing an arithmetic right shift on a two's complementary integer representation for an initial correction value of the prediction target pixel by a binary digit of 1. Accordingly, upon image encoding/decoding, computation complexity may be reduced.

An image decoding method according to the present invention includes reconstructing a residual block by inverse-quantizing and inverse-transforming an entropy-decoded residual block, generating a prediction block by performing intra prediction on a current block, and reconstructing an picture by adding the reconstructed residual block to the prediction block, wherein generating the prediction block includes generating a final prediction value of a prediction target pixel included in the current block based on a first prediction value of the prediction target pixel and a final correction value calculated by performing an arithmetic right shift on a two's complementary integer representation for an initial correction value of the prediction target pixel by a binary digit of 1. Accordingly, upon image encoding/decoding, computation complexity may be reduced.