Patent ID: 11785218

Abstract:
An image encoding method can include determining an intra prediction mode of a current prediction unit; constructing a mode group including three intra prediction modes using valid intra prediction modes of left and top blocks of the current prediction unit; determining a mode group indicator and a prediction mode index of the current prediction unit; and encoding the mode group indicator and the prediction mode index, in which the mode group indicator indicates whether or not the intra prediction mode of the current prediction unit belongs to the mode group, when the mode group indicator indicates that the intra prediction mode of the current prediction unit belongs to the mode group, the prediction mode index specifies the intra prediction mode of the current prediction unit in the mode group, when the mode group indicator indicates that the intra prediction mode of the current prediction unit does not belong to the mode group, the prediction mode index specifies the intra prediction mode of the current prediction unit among intra prediction modes besides the three intra prediction modes in the mode group.