Image decoding method using intra prediction mode

摘要

An image decoding method is provided which includes reconstructing an intra prediction mode group indicator and a prediction mode index of a current block, constructing a first group using valid intra prediction modes of left and top blocks, and determining the intra prediction mode corresponding to the prediction mode index and the intra prediction mode group indicator. Therefore, by causing the first group to include modes having a high possibility of being equal to the prediction mode of the current block on the basis of the valid intra prediction modes of the left and top blocks of the current block and determining the intra prediction mode group indicator and the prediction mode index to be encoded using the first group, it is possible to reduce an amount of information of the intra prediction mode to be encoded.

主权项

1. An image decoding method comprising:
reconstructing an intra prediction mode group indicator and a prediction mode index of a prediction unit; constructing a first group including three intra prediction modes using valid intra prediction modes of left and top blocks of the prediction unit; determining the intra prediction mode corresponding to the prediction mode index in the first group as the intra prediction mode of the prediction unit when the intra prediction mode group indicator indicates the first group; determining the intra prediction mode corresponding to the prediction mode index using the three intra prediction modes and the prediction mode index when the intra prediction mode group indicator does not indicate the first group; and creating a prediction block on the basis of the determined intra prediction mode when a size of the prediction unit 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 prediction unit 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 the intra prediction mode of the left block is not equal to the intra prediction mode of the top block and both of the intra prediction mode of the left block and the intra prediction mode of the top block are non-directional intra prediction modes, the first group includes the intra prediction modes of the left and top blocks and a vertical mode.