Intra prediction apparatus

An intra prediction apparatus, the apparatus comprising:

• a reference pixel generator configured to generate reference pixels when one or more unavailable reference pixels exist, and to adaptively filter reference pixels according to an intra prediction mode and a size of a prediction block;
• a prediction block generator configured to generate the prediction block using reference pixels determined by the intra prediction mode;
• and
• a prediction block post-processor configured to adaptively filter a part of the prediction block using the intra prediction mode,
• wherein the reference pixel generator adaptively filters the reference pixels according to the size of the prediction block for intra prediction modes existing between a horizontal mode and an intra prediction mode having a direction of 45° with reference to the horizontal mode,
• wherein, when the reference pixel generator filters the reference pixels for a second directional intra prediction mode, the reference pixel generator also filters the reference pixels for a first directional intra prediction mode that is closer to the intra prediction mode having the direction of 45° with reference to the horizontal mode than the second directional intra prediction mode is,
• wherein the second and the first directional intra prediction modes exist between the horizontal mode and the intra prediction mode having the direction of 45° with reference to the horizontal mode, and
• wherein the number of intra prediction modes in which the filter is applied increases as the size of the prediction block increases.