Patent ID: 9426471
Filing Date: 2016-08-23
CPC Classification: H04N

Claim Text:
1. An image decoding method comprising: reconstructing an intra prediction mode group indicator and a prediction mode index of a current block; constructing a Most Probable Mode (MPM) group including three intra prediction modes using valid intra prediction modes of left and top blocks of the current block; determining the intra prediction mode corresponding to the prediction mode index in the MPM group as the intra prediction mode of the current block when the intra prediction mode group indicator indicates the MPM group and determining the intra prediction mode of the current block using the three intra prediction modes of the MPM group and the prediction mode index when the intra prediction mode group indicator does not indicate the MPM group; and creating a prediction block on the basis of the determined intra prediction mode when a size of the current block is equal to a size of the prediction block, and creating a plurality of prediction blocks on the basis of the determined intra prediction mode when the size of the current block is larger than the size of the prediction block, wherein the size of the prediction block is determined depending on transform size information, and wherein when only one of the intra prediction modes of the left and top blocks of the current block is valid, two intra prediction modes are added to the MPM group and the two intra prediction modes are determined depending on the valid intra prediction mode.