Currently Online 
| Davy said: Do you have a valid source link that eyes cannot see the difference between 4k and 1440p in 2 meters distance below 65 inch ? |
RESOLUTION LIMIT OF THE EYE: HOW MANY PIXELS CAN WE SEE?
https://www.cl.cam.ac.uk/~rkm38/pdfs/ashraf2025_resolution_limit.pdf
To determine the ultimate resolution at which an image appears sharp to our eyes with no perceivable blur, we created an experimental setup with a sliding display, which allows for continuous control of the resolution. The lack of such control was the main limitation of the previous studies. We measure achromatic (black-white) and chromatic (red-green and yellow-violet) resolution limits for foveal vision, and at two eccentricities (10 and 20 deg). Our results demonstrate that the resolution limit is higher than what was previously believed, reaching 94 pixels-per-degree (ppd) for foveal achromatic vision (b&w), 89 ppd for red-green patterns, and 53 ppd for yellow-violet patterns. We also observe a much larger drop in the resolution limit for chromatic patterns (red-green and yellow-violet) than for achromatic.
Regtinal eccentricity means how far away from the center of your eye, the fovea. The graphs show how much can be gained with eye tracked foveated rendering as your visual acuity is already less than half 10 degrees off center. (total waste to render the whole screen at high resolution) And the best visual acuity is with black text on white. (no surprise)
This is consistent with a previous study by NHK (can't find it atm, it was old) that asked people which display looks better (different resolutions). That study found that above 90 ppd people were just guessing (50% correct in pointing at the higher resolution display)
2 (6.56ft) meters from 65" gives you 39.6 degrees viewing angle. (The screen occupies 39.6 degrees of your view horizontally)
3840 / 39.6 = 97 pixels per degree.
2560 / 39.6 = 65 pixels per degree.
So yeah 2m from 65" you can spot the benefit of 4K over 1440p (as I stated up there)
Although 20/20 vision is 60 pixels per degree, so you need to have better than that (which plenty people have, estimate 30% see better than 20/20 vision)
2m from 55" is 33.9 degrees.
3840 / 33.9 = 113 pixels per degree.
2560 / 33.9 = 76 pixels per degree.
With really good eyes (20/15 vision), you should still be able to spot a little better definition in high contrast patterns. (fine print)
https://www.visionworks.com/articles-how-rare-is-20-15-vision
2m from 52" is 32.1 degrees.
3840 / 32.1 = 120 pixels per degree
2560 / 32.1 = 80 pixels per degree
20/15 vision or better required to see the difference here.
Technically you can spot the difference at 2m below 65" with contrasting lines / b&w text. However in any normal video content the ability to determine the higher resolution display quickly drops off above 60 pixels per degree. Diminishing returns and all that.
There really is no need for consoles to go over 1440p. Leave that up to the pro consoles for the few sitting 12ft or less from a 120" screen.
However in VR this means anyone with 20/15 vision (80 ppd) can still spot the difference between 8K (70 ppd) and 12K (104 ppd) per eye at 110 degrees fov. For full immersion at the upper limit of human vision, 150 degrees per eye with 94ppd, 14,100 pixels needed to reach that. That's the theoretical upper limit.
(For 60ppd, the 20/20 standard, 9,000 pixels over 150 degrees will give a perfect picture)
Deep dive into the rabbit hole of human visual acuity :)
