Fast Algorithm for HEVC Intra Prediction Based on Adaptive Mode Decision and Early Termination of CU Partition

High Efficiency Video Coding (HEVC) introduces 35 intra prediction modes and a flexible quad-tree coding structure, which remarkably improve the coding efficiency. However, in intra prediction, the cost computation in Rough Mode Decision (RMD) process and Rate Distortion Optimized (RDO) process suffers from a pretty high complexity compared with H.264. To deal with this problem, a modified RMD process is proposed, in which all 35 prediction modes are divided into groups according to their phase angle to reduce the candidate modes.