[Galaxy Note 10.1 (2014 Edition) General] BarryH_GEG:
"Wall 'O text" warning.

Some of you might find this interesting - if so, read on. If not, feel free to move along to something you find more interesting.

You can't have a display resolution, quality, or PPI discussion without including the lowest common denominator which is the human eye itself. Visual acuity is what determines what we see, like jaggies on text on a mobile display. We also need to discuss the content being displayed itself. Some content benefits from higher PPI displays while other content less so.

Below are some excerpts from great articles talking about PPI, viewing distance, and what the human eye can actually process. It also introduces the term "acrminute sub tense" which is the point based on viewing distance that is the limit of what the human eye can resolve. For someone with 20/20 vision the maximum arcminute sub tense they can process is "1."

A smartphone is typically held at 10-12" away. At that distance a PPI of about 275-300 is the maximum the human eye can resolve. A 440 PPI display at 10-12" away has an arcminute sub tense of .66 which is useless because the 20/20 eye can't resolve anything below "1."

When Apple coined the name "Retina Display" it was because with the iPhone's display at 326 PPI it out-resolved the capabilities of the 20/20 human eye.

Immediately after hearing Apple's claim that the Retina Display outresolves the human eye, I snapped into optics mode and crunched the numbers, and tweeted that the results were valid.

In the days that followed, there was considerable debate about the validity of Apple's claims. However, nearly all of the debate really just hinged on a debate over angular resolution of the human eye, and a little more over viewing distance. They're both entirely conventions.

As you've probably discovered by now, the human eye resolution can really only be characterized in angular subtense. Hold something closer to your eye, and you can see smaller features better (in theory), move it further away, and you can't make out small spatial details. The minimum angle visible with the human eye is the angle at which features (for the most common definition, a black and white square wave) stop being visible, and are indistinguishable from each other.

Most measures of visual acuity test with this implicitly - the Snellen eye chart's use of the capital "E" is literally a perfect example, which has given rise to a "tumbling E" eye chart. At twenty feet, the capital E subtends 5 minutes of arc, and conveniently has five half cycles of white to black (from top to bottom). So 20/20 implicitly implies an angular resolution of 1 arcminute (1/60 degrees).

As an Optical Sciences and Engineering undergrad, I've had 1 arcminute drilled into my head more times than I can count as being the "normal" angular resolution of the human eye system. In practice, this is 20/20 vision, which is "normal," yet not perhaps the absolute maximum for human perfection. We can play games of course and argue that a small subset of the population has better than normal uncorrected vision, and thus an angular resolution of below 1 arcminute. I have above average uncorrected vision, which I've measured to be 20/15 on average, giving an angular resolution of approximately 0.75 arcminutes. Of course, the definitions stem from the spacing of cones in the fovea, the highest resolution part of the retina.

The other informational quantity needed to test the Retina Display claims is viewing distance. Again, there's a commonly agreed upon convention - standard viewing distance is considered to be 1 foot. This is another drilled into my brain number tossed around for comfortable viewing and reading. In practice, you can focus on objects much closer to your eye - this is called the near point and is often given as 10 inches, though as you get closer you increase strain aren't likely to keep it here.

http://www.anandtech.com/show/3794/the-iphone-4-review/4​

Here’s a good example. The Note II has a PPI of 267. Good, but far below the current standard for smartphones which is in the 400’s. At 10-12” away, the arcminute sub tense of the N2 is 1.073 which, for those with 20/20 vision, is near perfect. In other words, if you held a N2 (267 PPI) and N3 (386 PPI) 10-12” away assuming you have 20/20 vision you wouldn’t be able to notice the extra pixels and definition of the latter. For people with 20/15 vision the arcminute sub tense they’re capable of processing drops to .75. So, even at 10-12” away, they’d notice the difference. People with 20/20 vision would too if they held the device closer.

But there’s another catch. All these extra pixels being loaded on newer display only affect CGI and other computer generated content. For the reasons listed below, pictures and videos aren’t as impacted by a high PPI 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.

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

Back to the N10.1-14’s display. It doesn’t have a standard RGB stripe display which has been discussed in reviews. It’s RG-BW the “W” standing for the addition of a white sub-pixel. The presumed reason for the white pixel is to increase brightness while reducing energy draw. In other words, to achieve the same brightness level as a RGB display (like the one in the Nexus 10) which white is a big determiner of the added white pixel allows Samsung to do so at an overall lower illumination of the display. The N10.1-14’s display outperform the N10 in every metric including brightness.

http://www.anandtech.com/show/6386/samsung-galaxy-note-2-review-t-mobile-/8

But it gets better battery life on AnandTech’s web browsing test which is biased toward whites (8.533 vs. 8.170 hours) while having a much more power hungry CPU/GPU and a smaller battery (8,220 vs. 9,000 mAh). So Samsung's approach to the N10.1-14's display has a measurable benefit.

So what's the down side? From a sub-pixel perspective, the extra white pixel is reducing the overall count of RGB sub-pixels. With 25% of the overall sub-pixels being white, that’s the amount red, green, and blue have been collectively reduced. Distributing that over the three their overall count is reduced by 8% each; meaning rather than 299 per inch of each there are 275. That’s still at the count needed to achieve an arcminute sub tense of “1” for people with 20/20 vision at a viewing distance of 10-12” away. And 10-12" away is for smartphones with smaller displays. Tablets are typically held further away. And here’s the fun part, that number is still higher than the 264 PPI of the new iPad Air. So people saying they can see jaggies on the N10.1-14 when compared to the iPad Air can’t possibly be because the the former actually has more RGB pixels per inch than the latter in spite of the addition of the additional white pixels.

So folks can argue about their impressions of the N10.1-14’s display but things like visual acuity and how displays process non-computer generated content (video, pics) are immutable. Whether someone "likes" a display is hugely subjective and personal so for reasons other than RG-BW and PPI some folks may not like the N10.1-14's display or how it compares to others. That's fine and people should buy what makes them happy.