Ultra-HD televisions not noticeably better for typical viewer, scientists say | Television
Many modern living rooms are now dominated by a huge TV, but researchers say there’s no point opting for an ultra-high definition model.
Scientists from the University of Cambridge and Meta, the company that owns Facebook, have found that for an average-sized living room, a 4K or 8K display offers no noticeable advantage over a similarly sized 2K display, often used in computer monitors and laptops. In other words, there is no tangible difference in how sharp an image is to our eyes.
“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, first author of the study from the University of Cambridge.
Ashraf and his colleagues, writing in the journal Nature Communications, report how they went about determining the resolution limit of the human eye, noting that although 20/20 vision implies that the eye can distinguish 60 pixels per degree (PPD), most people with normal or corrected-to-normal vision can see better than that.
“If you design or judge display resolution solely based on 20/20 vision, you will underestimate what people can actually see,” Ashraf said. “That’s why we directly measured the number of pixels that people can actually distinguish.”
The team used a 27-inch 4K monitor mounted on a movable cage that allowed it to be moved closer or further away from the viewer. At each distance, 18 participants with normal vision, or vision corrected to normal, saw two types of images in random order. One type of image had pixel-wide vertical lines in black and white, red and green, or yellow and purple, while the other was just a simple gray block. Participants were then asked to indicate which of the two images contained the lines.
“When the lines become too thin or the screen resolution too high, the pattern is no different from a simple gray image,” Ashraf said. “We measured the point where people could barely make them out. That’s what we call the resolution limit.”
The researchers found that the human eye can resolve more detail than commonly thought, revealing that the average was 94 PPD for grayscale images viewed directly, while for red and green patterns it was 89 PPD. For yellow and purple patterns, it was lower, at 53 PPD.
In another experiment, 12 of the participants were presented with white text on a black background and vice versa, again at different distances, and were asked to indicate when the text looked as sharp as a sharp reference version.
“The resolution at which people no longer noticed the differences in the text matched what we saw with the line patterns,” Ashraf said.
The researchers published a chart showing different screen sizes and viewing distances, as well as the closest standard resolution that meets or slightly exceeds the visual limit for most people.
“In other words, if your setup falls into one of these boxes, you won’t gain any visible benefit from going higher,” Ashraf said.
The team also created a free online calculator that allows users to enter their viewing distance and screen size and resolution, with the results indicating whether the setup is above or below the resolution limit of the human eye. As a result, users can determine whether a higher resolution screen with more pixels would make a difference in what they see.
“If someone already owns a 44-inch 4K TV and looks at it from about 2.5 meters away, that’s already more detail than the eye can see,” Ashraf said. “Upgrading to an 8K version of the same size wouldn’t look sharper.”
