Many modern homes now feature large televisions, but a new study suggests that upgrading to an ultra-high-definition (4K or 8K) model may offer little visual benefit for most viewers.
Scientists from the University of Cambridge and Meta, the parent company of Facebook, found that for an average-sized living room, a 4K or 8K screen provides no noticeable difference in image sharpness compared with a 2K display, similar to those used in computer monitors and laptops.
“At a certain viewing distance, it doesn’t matter how many pixels you add. It’s just, I suppose, wasteful because your eye can’t really detect it,” said Dr. Maliha Ashraf, lead author of the study.
The research, published in Nature Communications, aimed to determine the resolution limit of the human eye. While 20/20 vision implies the ability to distinguish 60 pixels per degree (PPD), most people with normal or corrected vision can actually perceive more detail.
In the study, 18 participants with normal vision were shown images on a 27-inch 4K monitor mounted on a movable frame. Images included one-pixel-wide vertical lines in different colors and plain grey blocks. Participants were asked to identify which images contained the lines.
“When the lines become too fine or the screen resolution too high, the pattern looks no different from a plain grey image,” Ashraf said. This point defined the “resolution limit” of human vision.
Results showed the human eye can resolve more detail than commonly assumed: an average of 94 PPD for greyscale images, 89 PPD for red-green patterns, and 53 PPD for yellow-violet patterns. Further tests with text confirmed these findings.
The researchers also created a chart showing various screen sizes and viewing distances, along with the nearest standard resolution that meets or slightly exceeds most people’s visual limits. They provide an online calculator allowing users to check whether a higher-resolution TV would make a visible difference based on their setup.
“If someone already has a 4K, 44-inch TV and watches it from about 2.5 metres away, that’s already more detail than the eye can see. Upgrading to an 8K version of the same size wouldn’t look any sharper,” Ashraf explained.
For consumers, the study suggests that spending extra on ultra-HD televisions may not improve the viewing experience unless the screen is very large or the viewing distance is very close.