A fast intra prediction based on Haar transform in H.264/AVC

H.264/AVC is one of the state of the art in video compressing standards. It has advantages of low bit-rate and high image quality. However, the complexity of H.264/AVC encoder limits applications in the real time video communication. In this study, a fast intra prediction with Haar transform algorithm (FIPHTA) is proposed to simplify the complexity of luma intra prediction. For each luma macroblock (MB), a Haar transform is first executed. By observing LL coefficients, this MB will be classified as I16-MB, I4-MB, or both. An I16-MB indicates that this MB is smooth and only Intra 16×16 (I16) prediction modes are to be considered. An I4-MB indicates that this MB is textured and only Intra 4×4 (I4) prediction modes are to be considered. And the rest of MBs (both) have to consider both prediction modes as in the standard H.264/AVC. Next, to choose an I16 prediction mode for a MB, the vertical and horizontal energies of the LL coefficients are calculated to reduce candidate modes. Similarly, the pixel-based vertical and horizontal energies are calculated for a 4×4 block to reduce I4 candidate modes. The simulation showed that the proposed algorithm can maintain the similar mode selection results comparing to the full search algorithm of H.264 but with a remarkable computation deduction.