Methods for intra prediction, encoder and decoder

Abstract

A method for intra prediction includes: obtaining multiple previously reconstructed neighbouring blocks corresponding to a current processing block; determining prediction modes, that are signalled in a bitstream, corresponding to neighbouring blocks of the multiple previously reconstructed neighbouring blocks, to obtain multiple first prediction modes; if the multiple first prediction modes comprise at least two directional modes, taking directional modes comprised in the multiple first prediction modes as first prediction directions; performing, according to a preset operation rule, operation on multiple first prediction directions of the first prediction directions to obtain second prediction directions; obtaining a prediction mode set according to the second prediction directions and the multiple first prediction modes; and performing intra prediction on the current processing block based on the prediction mode set.