Improving intra 4 × 4 prediction for H.264

In H.264, the order of intra frame encoding is from left to right horizontally and from top to bottom vertically, so intra prediction reference pixels can only appear on the left side or upside of predictive block, without ideal predicted result sometimes. In this paper, a new intra 4 × 4 prediction algorithm based on flexible order of subblocks encoding was introduced, which improves the modes of intra prediction and the set of reference pixels for prediction. It realizes optimization of intra macroblock (MB) encoding by mode decision of subblock (SB) grouping and SB ordering. The experimental results show that, compared to the standard intra prediction mode of H.264, this proposed method can gain 0.4dBs of PSNR averagely.