How perception of ultra-high definition is modified by viewing distance and screen size

Abstract

Ultra High Definition (UHD) is a new technology, which main idea is to improve user’s perception of details and sensation of immersion in comparison with High Definition systems (HD). However, it is important to understand the influence of the new UHD technical parameters on user’s perception. Hence, to investigate the influence of the viewing distance, screen size and scene content on perceived video quality and feelings of users, a series of subjective experiments with four different contents (3 documentaries and 1 sport content) shooted by UHD camera were performed. These contents were displayed using three different image resolutions (SD, HD, UHD) and two UHD displays (55-inch and 84-inch). Each subject had to assess content for three different viewing distances (1.5, 3, 4.5 times of the screen height corresponding to optimal viewing distances of respectively UHD, HD, and close to SD optimal distance). Finally, 72 test conditions were evaluated. For each scene, observers reported their opinion on the perceived video quality using a 5-grade subjective scale. Results have shown that viewing distance has a significant influence on perceived quality. Moreover the highest MOS was obtained at optimal viewing for UHD, with a small difference between HD an UHD. At 3H and 4.5H, there is no difference from a statistical point of view. Screen size influences the perception of quality but not in the same way for the three image resolution and three viewing distances.