Intra mode coding in HEVC standard

Abstract

New High Efficiency Video Coding (HEVC) standard is designed to provide substantial coding efficiency improvement compared to H.264/AVC. Latest subjective testing shows 50% improvement has been achieved. Many new technologies contribute to the overall improvement. Intra prediction with 35 modes is one of the key improvements. Associated with that, there is a new intra mode coding method to efficiently signal the selected modes. This paper presents this new intra mode coding method that has been adopted by HEVC. In this method, the 35 intra modes are divided into two categories. One category includes 3 most probable modes (MPMs) and another category includes 32 remaining modes. In doing so, shorter codeword is used for coding MPMs and fixed length coding is used to code the remaining modes. Experimental results show the 3MPMs based method improve the coding efficiency compared to the prior art method used in H.264/AVC.