Video Restoration Against Yin-Yang Phasing**This work was supported by Natural Sciences and Engineering Research Council of Canada and Natural Science Foundation of China, grant NSFC 61331014.

A common video degradation problem, which is largely untreated in literature, is what we call Yin-Yang Phasing (YYP). YYP is characterized by involuntary, dramatic flip-flop in the intensity and possibly chromaticity of an object as the video plays. Such temporal artifacts occur under ill illumination conditions and are triggered by object or/and camera motions, which mislead the settings of camera's auto-exposure and white point. In this paper, we investigate the problem and propose a video restoration technique to suppress YYP artifacts and retain temporal consistency of objects appearance via inter-frame, spatially-adaptive, optimal tone mapping. The video quality can be further improved by a novel image enhancer designed in Weber's perception principle and by exploiting the second-order statistics of the scene. Experimental results are encouraging, pointing to an effective, practical solution for a common but surprisingly understudied problem.