A Novel Partial Prediction Algorithm for Fast 4x4 Intra Prediction Mode Decision in H.264/AVC

This paper proposes a partial prediction approach for fast mode decision in H.264/AVC 4 times 4 intra-prediction, exploiting the inherent symmetry existing in the spatial prediction modes. The high compression efficiency of H.264 comes with a price of high computational complexity. The intra-prediction process with its robust full intra mode search rate distortion optimization (RDO) technique to select the best mode for each macroblock is one such computational bottleneck. Unlike many fast algorithms which search for dominant edge in each block the existence of which is never assured, our algorithm quickly tries to find a closer prediction mode for each 4 times 4 block using a simple cost measure derived from the symmetry in all the prediction modes. The proposed algorithm only searches 3 or lesser modes instead of 9 for the 4 times 4 luma blocks. Experimental results reveal the significant computational savings achieved with slight PSNR degradation and bit-rate increase.