Assessing Quality Differences for 8K/UHD-2 and 4K/UHD-1 HDR Video Based on Viewing Distance

Abstract

One of the elements influencing users’ perception of video quality is the viewing distance. Although TVs have grown in size and resolution, viewers’ watching behavior and living room conditions have not changed equally and therefore viewers sit at distances farther than optimal. This gives rise to the question whether higher resolutions are perceptually beneficial in such scenarios. Therefore, this paper presents four studies that investigate the improvements offered by 8K/UHD-2 in comparison to 4K/UHD-1 using HDR videos with viewing distances between 0.50H and 3.00H with H representing the screen height. Study 1 identifies general effects while Study 2 refines the methodology and aims at finding the distance of subjective quality parity. Study 3 includes encoded contents to better represent a real-world streaming scenario. Study 4 looks into the effects of watching contents once or repeatedly per test and includes a wider variety of self created sources. The findings of the studies provide quantitative data on the effect of viewing distance, showing how the slight video quality advantage of 8K HDR against 4K HDR content at the design viewing distance of 0.80H diminishes as the viewing distance increases, with no or very little improvements beyond 2.60H, depending on the content. In general, the degree of enhancement is related to the spatial and temporal content complexity, as well as the bitrate settings employed for encoding. Additionally, it is found that, on average, subjects prefer to sit at viewing distances of around 2.20H. For most people this may be too far away to truly appreciate the improvements offered by the 8K resolution.

Keywords

• Subjective evaluation
• UHD
• video quality
• viewing conditions
• viewing distance