| CPC H04N 19/126 (2014.11) [H04N 19/11 (2014.11); H04N 19/124 (2014.11); H04N 19/136 (2014.11); H04N 19/157 (2014.11); H04N 19/176 (2014.11); H04N 19/463 (2014.11); H04N 19/593 (2014.11); H04N 19/61 (2014.11); H04N 19/70 (2014.11); H04N 19/105 (2014.11)] | 7 Claims |

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1. A method for encoding an image using intra prediction, the method comprising:
determining an intra prediction mode of a current block;
generating a mode group indicator and a prediction mode index, wherein the mode group indicator and the prediction mode index specify the intra prediction mode of the current block;
constructing a most probable mode (MPM) group including three intra prediction modes determined using a left intra prediction mode and an above intra prediction mode of the current block;
generating a prediction block based on the intra prediction mode of the current block specified by the mode group indicator and the prediction mode index;
generating a residual block of the current block using the prediction block;
generating a quantization block by transforming and quantizing the residual block;
scanning the quantized block using a scan pattern determined based on the intra prediction mode and the size of a transform unit; and
entropy-encoding the scanned information of the quantized block,
wherein when only one of a left intra prediction mode and an above intra prediction mode is available, the MPM group includes the available intra prediction mode and two additional intra prediction modes, and if the available intra prediction mode is one of two non-directional intra prediction modes, the two additional intra prediction modes are the other of the two non-directional intra prediction modes and a vertical mode, and if the available intra prediction mode is one of directional intra prediction modes, the two additional intra prediction modes are two non-directional intra prediction modes and
wherein when both of the left intra prediction mode and the above intra prediction mode are unavailable, the MPM group includes a DC mode, a Planar mode and the vertical mode.
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