An apparatus of decoding video data can include a prediction mode decoding module to derive a luma intra prediction mode and a chroma intra prediction mode; a prediction size determining module to determine a size of a luma transform unit and a size of a chroma transform unit using transform size information; a reference pixel generating module to generate referential pixels if at least one reference pixel is unavailable; and a reference pixel filtering module adaptively filter the reference pixels of a current luma block based on the luma intra prediction mode and the size of the luma transform unit. The apparatus can further include a prediction block generating module to generate prediction blocks of the current luma block and the current chroma block; and a residual bock generating module to generate residual blocks of the current luma block and the current chroma block.