Dominant edge direction based fast parameter estimation algorithm for sample adaptive offset in HEVC

In this paper, we present the fast parameter estimation algorithm for sample adaptive offset (SAO) in High Efficiency Video Coding (HEVC). The main idea of a proposed method is to simplify decision of the best SAO edge offset (EO) class based on the dominant edge direction information instead of searching all EO classes exhaustively. Prior to SAO encoding process, an edge map is created by using edge operator to detect edge detections on the image and a local edge direction histogram is then established for each coding tree block (CTB). Based on the distribution of the edge direction histogram, only one EO class is chosen for rate-distortion optimization (RDO) calculation. Experimental results show that the proposed method saves around 42.1% of the SAO encoding time only with 0.25% BD-rate degradation compared to HEVC reference software version 12.0.