Researchers found little benefit to 8K resolution when watching at a standard viewing distance

A research team at the University of Cambridge and Meta Reality Labs has measured the maximum resolution the human visual system can process and applied this finding to display viewing contexts.

“The eye’s resolution limit is higher than what was previously believed, reaching 94 pixels per degree (PPD) for foveal achromatic vision, 89PPD for red-green patterns, and 53PPD for yellow-violet patterns,” study authors reported in Nature Communications.

Their experimental setup used a sliding display to vary viewing distance, thereby controlling PPD directly. The 20/20-vision standard equates to about 60PPD. “This measurement has been widely accepted,” said lead author Dr Maliha Ashraf, “but no one had actually sat down and measured it for modern displays, rather than a wall chart of letters that was first developed in the 19th century”.

Participants in the study looked at patterns with very fine gradations, in shades of grey and in colour, and were asked whether they were able to see the lines in the image. The screen was moved towards and away from the viewer to measure PPD at different distances. PPD was also measured for central and peripheral vision.

When the authors mapped the resolution limits to modern televisions, they found that for a 44-inch 4K or 8K screen viewed at about 2.5 metres in a typical living room the added resolution offers no additional perceptible benefit. They said their model indicates for 4K and 8K displays the recommended International Telecommunication Union viewing distance ranges (1.6–3.2 times the screen height for 4K; 0.8–3.2 times for 8K) are overly conservative because “there is little benefit of 8K resolution when sited further than 1.3 display heights from the screen.”

The researchers also developed a free online calculator where people can enter the size of their TV room and the dimensions and resolution of their TV to determine the most suitable match.