Improved sample adaptive offset for HEVC

Sample adaptive offset (SAO) is the new in-loop filter in High Efficiency Video Coding (HEVC) standard. In this paper, the problems in the early version of SAO technique is discussed, and it is shown how the proposed methods improve its performance. It is proposed to restrict edge offset sign according to edge shape to reduce visual artifact caused by edge offset. It is also proposed to reduce number of band offset to facilitate implementation. Experimental results shows the proposed methods effectively reduce the artifact caused by edge offset, and reduce number of band offset by half without compromising coding efficiency.