A low-complexity HEVC intra prediction algorithm based on level and mode filtering

HEVC achieves a better coding efficiency relative to prior standards, but also involves increased complexity. For intra prediction, complexity is especially intensive due to a highly flexible coding unit structure and a large number of prediction modes. This paper presents a low-complexity intra prediction algorithm for HEVC. A fast preprocessing stage based on a simplified cost model is proposed. Based on its results, a level filtering scheme reduces the number of prediction unit levels that requires fine processing from 5 to 2. To supply level filtering decision with appropriate thresholds, a fast training method is also designed. A mode filtering scheme further reduces the maximum number of angular modes to be evaluated from 34 to 9. Complexity reduction from HM 3.0 is over 50% and stable for various sequences, which makes the proposed algorithm suitable for real-time applications. The corresponding bit rate increase is lower than 2.5%.