An apparatus for decoding image, the apparatus comprising: an intra prediction module for reconstructing an intra prediction mode of a current block, and for creating a prediction block of a current block or a sub block of the current block using reconstructed pixels and the intra prediction mode; an inverse scanning module for converting residual signals into a two-dimensional quantization block; an inverse quantization module for inversely quantizing the quantization block using a quantization parameter, wherein the inverse quantization module is configured to generate a quantization parameter by adding a quantization parameter predictor to a residual quantization parameter, and wherein the quantization parameter predictor is created using a quantization parameter of a left coding unit of a current coding unit and a quantization parameter of a top coding unit of the current coding unit; and an inverse transform module for inversely-transforming the inversely-quantized block, addition module for generating reconstructed block using the prediction block and the residual block, wherein the intra prediction module is further adapted to construct a most probable mode, MPM, group including three intra prediction modes using intra prediction modes of left and top blocks of the current block, and to reconstruct the intra prediction mode of the current block using the MPM group, an intra prediction mode group indicator and a prediction mode index, and the intra prediction mode group indicator and the prediction mode index is obtained from a received bit stream, and the intra prediction mode of the current block is determined as an intra prediction mode indicated by the prediction mode index among the intra prediction modes in the MPM group when intra prediction mode group indicator indicates the intra prediction mode of the current block is one of the intra prediction modes in the MPM group, wherein when only one of the intra prediction modes of a left and top blocks of the current block is present, the MPM group is comprised of the present intra prediction mode and two additional intra prediction modes, and wherein when the intra prediction modes of a left and top blocks of the current block are DC mode and planar mode, the MPM group includes DC mode, planar mode and vertical mode. an intra prediction module for reconstructing an intra prediction mode of a current block, and for creating a prediction block of a current block or a sub block of the current block using reconstructed pixels and the intra prediction mode; an inverse scanning module for converting residual signals into a two-dimensional quantization block; an inverse quantization module for inversely quantizing the quantization block using a quantization parameter, wherein the inverse quantization module is configured to generate a quantization parameter by adding a quantization parameter predictor to a residual quantization parameter, and wherein the quantization parameter predictor is created using a quantization parameter of a left coding unit of a current coding unit and a quantization parameter of a top coding unit of the current coding unit; and an inverse transform module for inversely-transforming the inversely-quantized block, addition module for generating reconstructed block using the prediction block and the residual block, wherein the intra prediction module is further adapted to construct a most probable mode, MPM, group including three intra prediction modes using intra prediction modes of left and top blocks of the current block, and to reconstruct the intra prediction mode of the current block using the MPM group, an intra prediction mode group indicator and a prediction mode index, and the intra prediction mode group indicator and the prediction mode index is obtained from a received bit stream, and the intra prediction mode of the current block is determined as an intra prediction mode indicated by the prediction mode index among the intra prediction modes in the MPM group when intra prediction mode group indicator indicates the intra prediction mode of the current block is one of the intra prediction modes in the MPM group, wherein when only one of the intra prediction modes of a left and top blocks of the current block is present, the MPM group is comprised of the present intra prediction mode and two additional intra prediction modes, and wherein when the intra prediction modes of a left and top blocks of the current block are DC mode and planar mode, the MPM group includes DC mode, planar mode and vertical mode.