At average living room distances, 8K displays offer "no distinguishable benefit" over 4K ones, writes Nicola Davis at The Guardian. Moreover, even 4K ones offer "no noticeable beneit over a similarly-sized 2K screen."
In other words, there is no tangible difference when it comes to how sharp an image appears to our eyes.
Dr Maliha Ashraf, the first author of the study from the University of Cambridge: "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."
300 pixels per inch is often given as a benchmark for what most people's eyes can resolve, but that's for screens a foot away. The chart below shows that, for most people, there's no point upgrading to 8k unless you're looking at an 80" display less than 3 meters away. And there was no point bothering with 4k unless your 50-inch display is closer than 2 meters. This works out to about 95ppm at 2 yards, the write-up suggests; other research on the angular size of foveal cones landed on 96ppm at 1.73 yards, not far off.
If all this sounds contrary to your experience, here's the methodology:
The team used a 27in, 4K monitor mounted on a mobile cage that enabled it to be moved towards or away from the viewer. t each distance, 18 participants with normal vision, or vision corrected to be normal, were shown two types of image in a random order. One type of image had one-pixel-wide vertical lines in black and white, red and green or yellow and violet, while the other was just a plain grey block. Participants were then asked to indicate which of the two images contained the lines.
That they used a tiny little 27 incher is funny, but it only needed to be big enough to show the pixel patterns used. Go play with their calculator, golden eyes!
I feel like I can tell 8K at greater distances than the chart suggests, but I wonder if I'm being cued by other things. One clever thing used in those in-store "attract mode" video loops is on-screen type being a little too small. Not so small you can't read it, but small enough to get you thinking "the resolution is too high." I am nonetheless looking forward to running Windows XP at 1:1 scaling on a 100-inch 32k display at 0.7m.
A tl;dr for consumers this fall might be "you don't want 8k, you want OLED."
