Maximum human eye visual acuity and screen dpi *spawn

[zed]

yes youre right about the 20/20 being 1 arcminute,
from wiki

In humans, the maximum acuity of a healthy, emmetropic eye (and even ametropic eyes with correctors) is approximately 20/16 to 20/12, so it is inaccurate to refer to 20/20 visual acuity as "perfect" vision. 20/20 is the visual acuity needed to discriminate two points separated by 1 arc minute—about 1/16 of an inch at 20 feet. This is because a 20/20 letter, E for example, has three limbs and two spaces in between them, giving 5 different detailed areas. The ability to resolve this therefore requires 1/5 of the letter's total arc, which in this case would be 1 minute. The significance of the 20/20 standard can best be thought of as the lower limit of normal or as a screening cutoff. When used as a screening test subjects that reach this level need no further investigation, even though the average visual acuity of healthy eyes is 20/16 to 20/12.

thus 20/20 vision is worse than average!

Under optimal conditions of good illumination, high contrast, and long line segments, the limit to vernier acuity is about 8 arc seconds or 0.13 arc minutes, compared to about 0.6 arc minutes (20/12) for normal visual acuity or the 0.4 arc minute diameter of a foveal cone.

FACT - the normal human eye can see the pixels on a retina device at 12"
hell my visions prolly 20/200 (not joking) & I can see the pixels at 35cm

If I have time (not looking good ATM, too much wasting time on the net, like now ) I might make a htmll5 page that tests a persons ability to see the pixels

 

[(((interference)))]

A single line will always be discernible. Use the test in the post above and see at which point you can't tell the difference. A better test would be to randomize the circles, and have you choose which is horizontal. Otherwise you get confirmation bias, like in audio. On my iPad 3, it's at about 16" that I lose the ability to tell.

But I can still see the single pixel at 2 feet away from the screen.
As you can still distinguish individual pixels doesn't that mean it isn't a 'true retina' display?

With the other test, I can't make out the horizonal and vertical lines from more than a foot away, but the colour of the two circles isn't identical (the right one is slightly lighter).

 

[egoless]

Fuel for the only resolution matters debate. When asked why the arm version of Microsoft Surface is 1366x768 in an AMA, the response was:

Hey this is Stevie. Screen resolution is one component of perceived detail. The true measure of resolvability of a screen called Modulation Transfer Function (MTF), not Pixels. MTF is a combination of both contrast and resolution. There are over a dozen subsystems that effect this MTF number..

Most folks just focus on one number out of dozens that effect perceived detail. Without good contrast resolution decreases. Check out contrast sensitivity of the human eye graph (http://www.telescope-optics.net/images/eye_contrast.PNG) and if you want more see the links below.

Full answer here: http://www.neowin.net/news/microsoft-explains-why-they-chose-1366768-resolution-for-the-surface-rt. Also makes you wonder about 360's gamma curve setting that's based on what most say looks better despite the hard numbers.

 

[Rangers]

Fuel for the only resolution matters debate. When asked why the arm version of Microsoft Surface is 1366x768 in an AMA, the response was:



Full answer here: http://www.neowin.net/news/microsoft-explains-why-they-chose-1366768-resolution-for-the-surface-rt. Also makes you wonder about 360's gamma curve setting that's based on what most say looks better despite the hard numbers.

Yeah, I do think it's funny just today we have this big brouhaha over the Surface not having enough resolution. I have people on my twitter, technical people, saying things like "once you use a high res tablet like the Apple (copyright, trademark) iPad 3 (copyright, trademark), 1366 is woefully lacking, bad job MS" It seems to be important sometimes?

 

[Rurouni]

On monitor where the distance to my eyes is around 60cm, yes, I can easily differentiate 720p vs 1080p. From my tv where I sit around 2m from it, I can't. I already try making 1 pixel line and put it on my tv, all I see is a faint line. The same 1 pixel line (not scaled) but with 720p, yes, the line is slightly darker (because it's thicker), but still faint that for me it wouldn't matter. I try displaying 1080p content, then scale it down to 720p, I still couldn't tell the difference.
Even on my monitor, if the content is smooth (not aliased), I need to use layer difference (in Photoshop) to make sure that the content is 1080p.
For me, if a game is properly anti aliased, 720p vs 1080p shouldn't really matter, unless you've got a big enough tv/monitor.