A study on perception of mobile video with surrounding contextual influences
Contemporary users have been viewing video contents via mobile devices from virtually anywhere and at any time. One common experience these mobile users feel is the significant difference in visual perception when viewing context changes, e.g. from indoor to outdoor. Conventional video quality assessment (VQA) defined under ITU-T recommendations outlines a set of evaluation conditions that need to be strictly followed. These conditions, including viewing distance, room illumination, display brightness and chromaticity of background are historically tuned to simulate the living room television viewing scenario. In this paper, we first present a set of contextual factors that are unique for mobile video and are substantially different from conventional living room evaluation conditions. We design and perform a series of subjective tests to evaluate the influence of these contextual factors that frequently encountered in the case of mobile video. These evaluation results show that (1) perceptual quality is highly correlated with the con-text factors; (2) with the presence of the contextual visual interference, the viewers shall spot less video signal distortion and have lower expectations on the quality of mobile video. We then pro-pose a VQA model based on the Just Noticeable Distortion (JND) theory and we prove that this model is able to provide context aware prediction of perceived mobile video quality. Finally, we also discuss its application of this VQA model in the design of video transmission systems.