To perform inter prediction, whether a motion prediction method of a prediction unit included in a corresponding coding unit is a skip mode, a merge mode or a AMVP mode may be determined in a coding unit.

An intra prediction unit 235 may generate a prediction block based on pixel information in a current picture. When a prediction unit is a prediction unit which performs intra prediction, intra prediction may be performed based on intra prediction mode information of a prediction unit provided by an encoding device. An intra prediction unit 235 may include an AIS (adaptive intra smoothing) filter, a reference pixel interpolation unit and a DC filter. An AIS filter is a part performing filtering for a reference pixel of a current block and may be applied by determining whether a filter is applied according to a prediction mode of a current prediction unit. AIS filtering may be performed for a reference pixel of a current block by using a prediction mode of a prediction unit and AIS filter information provided by an encoding device. When a prediction mode of a current block is a mode where AIS filtering is not performed, an AIS filter may not be applied.

When a prediction mode of a prediction unit is a prediction unit in which intra prediction is performed based on a pixel value interpolating a reference pixel, a reference pixel interpolation unit may interpolate a reference pixel to generate a reference pixel in a pixel unit which is equal to or less than an integer value. When a prediction mode of a current prediction unit is a prediction mode which generates a prediction block without interpolating a reference pixel, a reference pixel may not be interpolated. A DC filter may generate a prediction block through filtering when a prediction mode of a current block is a DC mode.