Television and tech companies constantly release screens with higher resolutions, such as 4K displays with 4,000 horizontal pixels. However, researchers are questioning whether we have hit a resolution limit for the human eye. The sheer energy and resources required to manufacture and power these ultra-high-resolution devices are also an environmental concern.
A team of scientists from the University of Cambridge and Meta Reality Labs developed a new way to measure human vision capabilities, published in Nature Communications. Their findings offer a modern update to one of the oldest tests in eye care, aiming to determine if a “tipping point” for resolution exists.
The Snellen chart, a traditional part of an eye exam, has been a familiar part for over 160 years. Named after its Dutch creator, the test has remained mostly unchanged. However, modern displays have changed the way we look at screens.
“This measurement has been widely accepted, 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,” study co-author University of Cambridge computer scientist Maliha Ashraf said in a statement.
Snellen chart replaced with a clever digital setup
The research team, led by Ashraf, replaced the old-school paper eye chart, called the Snellen chart, with a clever new digital setup. They used a special screen that could move back and forth, allowing them to measure exactly what someone’s eye could see while looking at different patterns on the display. Instead of just caring about the total number of pixels on the screen (like a 4K resolution count), they focused on a more personalised measurement called Pixels Per Degree (PPD). Think of PPD as how many tiny squares (pixels) fit into just one degree of your total view when you look at the screen. This is a much better way to figure out how sharp a picture looks to an individual person from their unique viewing spot, rather than just knowing the screen’s overall pixel total.
For the experiment, volunteers looked at this special screen, which displayed various patterns in both grayscale (shades of gray) and colour. As the screen was moved closer and farther away, and even to the side to test their peripheral vision, the participants simply pointed out the exact moment they could distinguish the image’s individual lines. The traditional 20/20 vision standard suggests the average eye should be able to see detail when the screen is at 60 PPD. Interestingly, the scientists found that people’s eyes often see things better than the old standard, though the exact limit depends on what they are looking at.
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