Image decoding apparatus

Abstract

An image decoding device is provided which reconstructs an intra prediction mode of a current prediction unit using a prediction mode group indicator and a prediction mode index, determines a size of a sub block when intra prediction is performed on each sub block of the current prediction unit, and creates reference pixels and a prediction block per sub block. Therefore, by causing the first group to include modes having a high possibility of being equal to the prediction mode of the current block and determining the intra prediction mode group indicator and the prediction mode index, it is possible to reduce an amount of information of the intra prediction mode to be encoded. Also, by creating a prediction block very similar to the current block, the number of bits to be encoded and to be decoded are reduced.