Method of deriving quantization parameter with differental and predicted quantization parameters

Abstract

A method for encoding an image using intra prediction can include determining an intra prediction mode of a current block; generating a mode group indicator and a prediction mode index; constructing a most probable mode (MPM) group including three intra prediction modes determined using a left and an above intra prediction mode of the current block; determining whether all reference pixels of the current block are available; generating reference pixels if one or more reference pixels of the current block are unavailable; adaptively filtering the reference pixels based on the intra prediction mode and the size of the current block, wherein if the size of the current block is 4×4, the reference pixels are not filtered, and if the size of the current block is larger than 4×4, the number of intra prediction mode where the reference pixels are filtered increases as the current block becomes larger; generating the prediction block using the reference pixels.