Flexible sub block ordering based intra 4/SPL times/4 prediction

In H.264, Intra prediction is employed to reduce energy of prediction error to be transmitted. Because the order of Intra frame encoding is from left to right horizontally and from top to bottom vertically, intra prediction reference pels can only appear on the left side or upside of the block to be predicted, so predicted results are not ideal sometimes. In this paper, a new intra 4 times 4 prediction algorithm based on flexible order of sub blocks encoding is introduced, which improved the modes of intra prediction and the set of reference pels for prediction. Experimental results show that compared to the standard intra prediction mode of H.264, this proposed method can gain 0.4 dBs of PSNR averagely.