[Galaxy Note 3 General] BarryH_GEG:
You're right, most people don't have perfect vision or even 20/20. For them, this whole discussion is sort of mute as they won't be seeing pixels any way. People that are 20/10 and/or regularly look at displays at a 5" distance should definately buy non-PenTile displays.

Visual acuity (VA) is acuteness or clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain.[1]

Visual acuity is a measure of the spatial resolution of the visual processing system. VA is tested by requiring the person whose vision is being tested to identify characters (like letters and numbers) on a chart from a set distance. Chart characters are represented as black symbols against a white background (for maximum contrast). The distance between the person's eyes and the testing chart is set at a sufficient distance to approximate infinity in the way the lens attempts to focus. Normal visual acuity is commonly referred to as 20/20 vision, the metric equivalent of which is 6/6 vision. At 20 feet or 6 metres, a human eye with nominal performance is able to separate lines that are one arcminute apart (equivalent to lines that are spaced 1.75 mm apart).

http://en.wikipedia.org/wiki/Visual_acuity​

“Retina Display” is a great marketing name, and it’s the sharpest smartphone display available, 23 percent sharper than the nearest competitor, but objectively it does not meet the quantitative criteria for being a true Retina Display – it’s about a factor of two lower than the acuity of the human Retina. Rather, the iPhone 4 has a “20/20 Vision Display” because when it is held more than 10.5 inches away, a person with 20/20 Vision will not be able to resolve the iPhone 4 screen pixels, which are at 326 ppi (1 arc-minute resolution). But 20/20 Vision is the legal definition of “Normal Vision,” which is at the lower end of true normal vision. There are in fact lots of people with much better than 20/20 Vision, and for most people visual acuity is limited by blurring from the lens in the eye. The best human vision is about 20/10 Vision, twice as good as 20/20 Vision, and that is what corresponds to the acuity of the Retina. So to be a “True Retina Display” a screen needs about 652 ppi at 10.5 inches, or 572 ppi at 12 inches. Unfortunately, a “20/20 Vision Display” doesn’t sound anywhere near as enticing as a “Retina Display” so marketing and science don’t see eye-to-eye on this.

http://www.displaymate.com/iPhone_4_ShootOut.htm#Retina​

When 1080p is crammed into such a relatively small package, does it really matter to the human eye?

We took this question to Dr. Raymond Soneira, president and CEO of DisplayMate, a company that produces calibration software for displays of all types. Dr. Soneira has also been known to publish display shoot-outs that pit the latest smartphones against each other in the battle for the best display.

When it comes to 1080p on a smartphone, he admits that it might not matter for the most casual users. "For some people, it is possible to tell the difference if we were to sit down and study a [1080p] display and a [720p] display, side-by-side," he said in a phone interview with Ars. "If you’re really a fanatic and you study images, or you have some professional applications and you’re really into displays, then it may make a visual difference for you."

For most people, though, it won't matter. Photos are inherently fuzzy, so it won’t matter whether they’re viewed on a 1920×1080 or 1280×720 smartphone display; you’ll still see their imperfections. "Even the tiniest image detail in a photograph is always spread over more than one pixel," Dr. Soneira explained in a follow-up e-mail. "The image detail is never perfectly aligned with the pixel structure of the display." Videos are even worse: not only are they fuzzy like photographs, but the pictures are constantly moving. Even if the images were sharp, the human brain couldn’t zero in on content that’s appearing for only a fraction of a second on such a small display. "For ordinary viewing of videos, 1920×1080 is really not going to make a visual difference," adds Dr. Soneira.

Where a 1080p smartphone display could really make an impact is with computer-generated content—that is, the user interface, buttons, and text. "Only computer-generated images make full use of the pixel resolution of the display," says Dr. Soneira. "For graphics and text, maybe you want that kind of sharpness." Like desktop computers, smartphone displays can also utilize sub-pixel rendering, which helps improve the visual sharpness of computer-generated graphics.

A 1080p display might also be useful for simply viewing 1920×1080 content and not worrying about scaling. "Every time you rescale content that’s scaled for some other resolution, it’s not going to look as good. So there’s an advantage to living with 1920×1080 even if your eye can’t appreciate the fine details, because you don’t have the rescaling artifacts," he says.

For most uses, however, the extra sharpness of a 1080p display is wasted. In Dr. Soneira's third-generation iPad display shoot-out, he explains that because most adults don't actually have true 20/20 vision—even with glasses or contact lenses—when they view a display further away than recommended, the eyes can no longer fully resolve the sharpness. The iPhone’s Retina display makes a good example of this. "If you use the legal definition for 20/20 vision, the resolution for the iPhone at 326 ppi becomes a ‘retina’ display at 10.5 inches," says Dr. Soneira, because that’s the viewing distance where the image on the screen will appear optimally sharp. After about 15 inches, "the much higher 326 ppi is 'wasted' because the eye can't resolve sharpness above 229 ppi." The further away a person gets, the more gradual the reduction in perceived image sharpness.

http://arstechnica.com/gadgets/2012/10/1080p-on-a-smartphone-screencan-it-possibly-matter/​

Good Lord. :rolleyes:

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