4k resolution coming

http://www.psy.vanderbilt.edu/courses/hon185/SpatialFrequency/SpatialFrequency.html

 

Man, I bet it must be interesting to be 5 inches away from a screen that is at least 30 inches across its diagonal. Because unless I am missing something upstream, all of this started with a TV / monitor panel example. And the subsequent talk was in the context of NOT having your eyes stuck 1 inch away from such a screen, but rather at a comfortable distance. But let us not be hampered by such details whilst condescendingly asking someone not to be rude.

 

My apologies, but I replied to a reply about a 538dpi 5.5inch screen, just 3 posts earlier. So, yes, one could say that you missed something upstream. No hard feelings though, can happen to anyone.

 

5" is ridiculously short distance from a smart phone... I personally can't even focus to my 4.3" screen from that distance (just tried), not to mention it looks quite ridiculous to keep the phone right in your face. How the hell do you type from that distance?

Perhaps your "~5 inches" is more like 8-10" I sure as hell never see anyone keeping their phones that close to their faces.

 

Alex, I agree with you that for phones more than 350-400 ppi is not necessary.

What I am trying to explain to you is that current 1920 X 1080 22-24 inch displays are crappy and urgently need improvements in ppi.

Also, the same for 1600 X 900 17 inch laptop displays. It's a joke.

 

5" is right up in front of your face. It's an unnatural distance. Google "people using smartphones" images and you'll see a lot of people holding their phone a good 12+ inches away, which is a far more comfortable viewing distance. The closest I can see in a glance through those images is this one, which I estimate with the aid of a ruler to be about 9-10".

You are very much the exception if you really do hold a 5" screen phone 5" from your face (save for watching media or taking photos). If the people around you are using their phones that way, you live in an interesting part of the world.

Furthermore, this only ties in with what's been said about resolution being FOV dependent. The reason you hold your phone close is to get a larger FOV. A 5" screen 5" from your face will be a 50 degree viewing angle, the same as a THX 2.35:1 screen recommendation. At 1 arcminute resolving power of a typical viewer, that'd warrant a 3000 pixel diagonal screen, or about 2600 horizontal pixels. Which is the LG display you linked to, and which I said would only be of value if you hold the phone a few inches from your face. Whether or not people really do do that is pretty irrelevant for the topic of 4k displays though. The value of any 4k display is FOV. It can occupy some 60 degrees FOV at 'full resolution' and provide either screen estate (look around the display) or background immersion (display occludes the rest of the world).

 

It depends on viewing distance! The ppi itself is not intrinsically crappy. A 22" screen that's viewed from up close and filling a larger FOV will not have enough resolution at 1080p to have no visible pixel aliasing, but if viewed from a little further way to occupy a smaller FOV, then 1080p is perfectly fine.

If you want your 22" monitor to fill a 60 degree FOV, like your 5" phone it'll need to be ~2600 pixels wide. On a 22" 16:10 monitor with an 18.5" screen width, that'll need to be ~140 ppi*, and you'll only be able to see a small part of it at a time. If you'd rather have a 40 degree FOV, you'd need a diagonal resolution of 2400 pixels, a horizontal resolution of 2035 pixels, and a ppi on a 22" screen of 110.

A 16:9 1080p display is retina quality (detail of one arcminute size) with a FOV of 36 degrees, irrespective of how big the screen is or how many ppi it has.


* this is slightly inaccurate as I used the horizontal res from the 16:9 phone screen whereas the horizontal res will be different in a 16:10 monitor, but I can't be bothered to recalculate as there's not going to be a huge difference; certainly not to change the nature of the demonstration.

 

Yes, even at relatively high distance as more than one full arm length, the image can look quite grainy and extremely lower quality than an image from my phone from any given distance.

So, you essentially agree that there are limitations- I want them non-existent Or high enough ppi so you are not limited to stay at large distance, so you experience something relatively good

 

Yes, of course there are.

That's unreasonable. A large TV giving a 60 degree FOV at 4k is not designed to be viewed from less than a foot (or rather, several) away. If you want any screen to be perfect quality at any viewing resolution, you'd need 500 ppi (for viewing from 5"). A 60" TV that provides a great picture at distance would then need about 26 thousand pixels in the horizontal direction and 15 thousand in the vertical for a total of 383 megapixels, all of which are unviewable at any given moment with full resolve.

Every display is made for a minimum sane viewing distance. Its own PPI doesn't need to be higher than its intended FOV. It's the FOV that's important, and something that no-one covers. If someone buys a monitor wanting a higher FOV than it is really suitable for, and sits closer to accomplish that, they will lament its lack of higher screen resolution. Which is, I believe, what you are really talking about, but you can't logically talk about displays that way using PPI, which was my earlier point. Display resolution should be qualified in terms of resolution relative to FOV. Monitors should be sold as 35, 40, 50 degrees FOV at x distance, providing retina quality at that distance, lower quality and larger FOV is you sit nearer.

 

Whatever. Make it 8inches, I don't have a ruler. My point is: I can see the stair casing on the 'A' and '/' etc. Which means that, for a cell phone, 330ppi is most definitely not past the limit of the human eye. That number is often claimed for 20/20 vision. There are quite a bit if people who have better vision than that.

 

I think you're still missing the point that is being made.

PPI by itself is a meaningless number when talking about human visual acuity, In order for PPI to "make sense" in human visual perception, you absolutely must consider distance and field of view. So when you say "fine, eight inches, it doesn't matter because PPI..." then you're still missing the point.

The move from five inches to eight inches of viewing distance is incredibly significant when talking about your organic eyeballs seeing that output. You've increased the distance by 60% which has a critical affect on how much resolution your eyes can make out.

Yes, you can still make out the stairsteps, that's fine. Finding a resolution where you can't see those "stairsteps" is a function of BOTH pixel density AND distance. That's the point being driven home about the usefulness of 4K displays at home, and of the "typical" distance between the image on a phone display and the back of your eyeball as a viewer of that image.

 

Dude,
I don't disagree with anything you're saying.

I'm just saying that larger than 300ppi resolution for a 5.5inch screen is not pointless.

Because, tadaaaa, people tend to put a phone screen close enough to their eyeballs that 300ppi is visible.

That is all.

 

I sit close enough to my monitor so that it fills my fov (in the horizontal)

 

It actually isn't completely pointless. Would be great as a screen for an even higher resolution Oculus Rift. Big thing there of course is the use of optics.

 

Oculus Rift is actually quite interesting, because it has a relatively large FOV (90 degrees), and will need a very high resolution (more than 36,000 pixels) to be "retina." Of course, reducing latency is still more important as it's a major point in human vision perception of reality.

 

Then what is meaningful? The type of the display? It can be the best quality but if it comes with low ppi it will still be crappy.

Unfortunately, I will tell you for n-time that human vision has the good quality to adjust itself and when you deliver superior image, then you realise how crappy the old one had been prior to the change. It is subjective- the example is simple- use an old crappy phone and you will be satisfied with the quality because your brain hasn't seen anything better- once you get the better, you will understand how crappy the old one is in respect to it.

As simple as that.

Once you get high ppi displays for PC you will realise how crappy these today are.

Edit:

I am playing with my phone and for example with camera on, I look at the display to see whether the image is the same as what I see without the phone- unfortunately looking around without the phone still delivers the real visuals, while the phone is not capable to fully re-create reality as it were through the window.

 

It's not long ago I've looked at a high ppi screen, a Galaxy Note with a 5.3" 1280x800 one. I've just learned it's an OLED, which makes sense.
I thought lol it looks like paper.

On laser printers you have a choice between 300 and 600 dpi and well 300 is damn good enough. But maybe 600 is good for old people who need to read legalese small print with a looking glass, or it's like supersampling and would deal with noise patterns.

It would be fun if you could have more radical options like in the old days.. High dpi monochrome screen? Here's a way to have crazy res with only dual link dvi or displayport.
Hell in the Middle Ages, the Xerox workstation had crazy high res for the day, 606x808 1bit (years before home computers and consoles came with something like 256x192). And in the Renaissance Sun or Next computers would give you as the "cheapest" option some 1152x900 monochrome display when 640x480 was high end for consumers.

Xerox Alto kind of was a proprotype system that appeared to deal with display the same way as paper btw, and Next had Display Postscript which does what it says it is. So high ppi was solved for apps and OS before we built a huge legacy of windows 3.1, 95 and XP low ppi apps. (X11 apps, too..)

 

PPI in relation to viewing distance, which is what Albuquerque said ("PPI by itself is a meaningless number when talking about human visual acuity, you absolutely must consider distance and field of view") and what I've said. Quality of an image as perceived by the viewer is not determined by the display's pixels density, but as a function of the display's pixel density combined with the viewing distance.

 

I remember that example of boards on stadiums where pixel density is horrible and you need large distance in order to not see the grainy image.
However, with these boards, regardless of distance the image will never be corresponding to reality or what your eyes could have seen through a window for example- so in that case you still need higher ppi.

Isn't it right?

 

No. If you look at a sufficiently large Jumbotron from a large enough distance to make each pixel smaller than the size your eyes can make each pixels apart, that's enough PPI. Note the key word here is "distance."

For a very quick, back of an envelope computation, assuming 0.3 arc minute per pixel (which is very close to the limit of normal human vision), you can divide 11459 by distance (in inches) to get a "good" PPI number (or conversely, divide 11459 by a PPI number to get a "good" distance). For example, watching from 3 meters, or about 120 inches, divide 11459 by 120 you get around 95.5 DPI. That means if you look at your normal 96 DPI computer monitor from 3 meters, it's as close as "retina" as you want (though obviously most computer monitors would be too small for this distance).

Or, if you want to know from how far you look at a Jumbotron to be "retina", you can divide 11459 by its PPI. Let say a Jumbotron with 2 PPI, then you'll need to look at it from 11459 / 2 = 5729.5 inches to make it "retina." That's around 145 meters.