A fast intra mode decision method based on reduction of the number of modes in HEVC standard

High efficiency video coding (HEVC) standard, introduced by joint collaborative team on video coding (JCT-VC) is the newest international standard of video compression. This standard provides more compression and better video quality, compared to the previous standards such as H.264. The higher compression efficiency is obtained at the cost of an increase in the computational load. One of the portions which imposes high computational load to encoder is the intra prediction unit. In HEVC, 35 modes are proposed for intra prediction to improve the compression efficiency. To reduce the computational load of intra prediction, HEVC uses a pre-processing step, called Rough Mode Decision (RMD). It selects a number of best prediction modes. Then, using Rate Distortion Optimization (RDO) process, the encoder selects the best prediction mode. We reduced the number of the tested modes in RMD from 35 to 19 in our proposed method. Moreover, we reduced the number of the selected modes through the RMD step in order to decrease the encoding time. Simulation results indicate 14.2% reduction in the encoding time whereas the R-D specification in general remains unchanged.