Rotational Weighted Averaged Template Matching for Intra Prediction Intra prediction is an important step in video coding, which improves compression efficiency by reducing spatial redundancy. High Efficiency Video Coding (HEVC) has a total of 35 prediction modes, including 33 angular modes and a DC mode as well as a Planar mode. These modes usually exploit local directional signal correlations. In order to represent prediction blocks with nonlocal complex texture and content, template matching was proposed. However, there may be blocks exist in an image with the same content but with different rotation angles. In this paper, we propose an improved intra template matching prediction method, which extends the intra template matching technique by making the matched template rotated during template matching process. Also, in order to improve the efficiency of prediction, this paper adopts a weighted template matching method to predict the target block by averaging sum of the weighted corresponding remote blocks of three most similar remote templates. The experimental results show that for AllIntra configuration, the overall coding gain in BDrate is about 5.1% at most and 0.63% on average comparing to averaged template matching in HEVC. Moreover, our approach can achieve 13.2% coding gain at most and 2.0% on average comparing to HEVC test model HM16.9.

Fast Intra size decision and mode decision algorithm for HEVC intra coding The latest High Efficiency Video Coding (HEVC) standard could achieve much higher coding efficiency than the current mainstream video coding standards (H.264AVC). Compared with H.264AVC, H.265 saves 50% cost than H.264AVC at the same quality. But compression ratio gets improved with at least 24 times increase in computational complexity. HEVC provides a quadtree based coding unit (CU) block partitioning structure. The predication mode of CU has been extended from 8 to 35. To alleviate the encoder computational complexity, we proposed an algorithm based on complexity of CU and cart decision tree to determine whether the current CU should be divided into quadtree. In the mode decision process, we reduce the number of candidate modes involved in the rough mode decision(RMD) and the rate distortion optimization (RDO) process. The experiment results demonstrate that the proposed algorithm could significantly reduce compression time with little loss.