Image decoding device which obtains predicted value of coding unit using weighted average

An apparatus for decoding an image, the apparatus comprising:nan entropy decoder which obtains a split information from a bitstream;a splitter which determines at least one coding unit included in a maximum coding unit by splitting the maximum coding unit according to the split information, and determines a prediction unit of a current coding unit by obtaining at least one prediction unit from the current coding unit; anda predictor which obtains a first predicted value of a current prediction unit by using neighboring pixels of the current prediction unit, and obtains a second predicted value of pixels of the current prediction unit located on a top border and a left border of the current coding unit by using the obtained first predicted value and at least one neighboring pixel,wherein:the second predicted value of the current prediction unit is obtained by using the at least one neighboring pixel and a weighted value of the obtained first predicted value,the image is split into a plurality of maximum coding units, according to information about a maximum size of a coding unit,the maximum coding unit is hierarchically split into one or more coding units of depths according to the split information,a coding unit of a current depth is one of rectangular data units split from a coding unit of an upper depth,when the split information indicates a split for the current depth, the coding unit of the current depth is split into coding units of a lower depth, independently from neighboring coding units, andwhen the split information indicates a non-split of the lower depth, at least one prediction unit is obtained from the coding unit of the lower depth.