

The New iPad's Screen Under the Microscope - slig
http://ignorethecode.net/blog/2012/03/16/ipad_screen_microscope/

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jader201
I inspected the 3rd gen iPad image, trying to figure out roughly how much gap
there is between rows, because it looks unexpectedly large. It looks like the
pixel-to-gap ratio is about 9:5. This would seem to indicate that the screen
is 35.7% black.

Obviously, the eye doesn't perceive this large of a gap at no magnification,
but still, I was surprised at how much of a gap there is between rows.

(Contrast this to the iPhone 4S, which is about 9:3.6, or 28.6% black.)

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ajross
But it's a power efficienty issue. The black areas are covering up backlight
areas that otherwise would show through as useful illumination. There was a
discussion yesterday about this in the iPad teardown thread. I was surprised
about the apparent power consumption, and this was posited as one of the
reasons.

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unwind
It's painful to see that some people have OpenPandoras, and use them to take
reference images to show differences in LCD (and OLED) screen properties.

Me, I just want to hold it. Smell it. Feel it. I'm sure I will too, in another
2 months from now.

(Explanation: the OpenPandora (<http://openpandora.org/>) is a custom portable
QWERTY Linux clamshell ultra-console. Or it was, three years ago when I
ordered mine. Still waiting for delivery, it's a very small operation and
they've had some hiccups along the way.)

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LukasMathis
I use it for other things, too :-)

~~~
seclorum
I use mine (I have two) for development mostly. Oh, a bit of MAME with my
legal roms too, now and then ..

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lusr
Man this guy's got a lot of nice toys. What are the gaps in pixels for?
Circuity? Or does it have something to do with the amount of light that needs
to be transmitted vs. horizontal/vertical resolution of the eye to represent a
square pixel?

~~~
pmjordan
Each subpixel needs a transistor (hence TFT - thin film transistor) to drive
it, along with the addressing conductors to drive it. I suspect the
transistors have to have a certain minimum size to be reliable enough, so
their relative size to the size of the whole pixel grows with decreasing pixel
size. I'm sure they'd make them smaller if they could, as the black areas
absorb a lot of precious backlight energy. I also recall reading about
progress with making the transistors (which are typically silicon-on-glass)
transparent, but I guess that tech isn't ready yet.

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tocomment
If you just make the pixels 100 times smaller you could have a holodeck.

Source: <http://www.phased-array.com/1996-Book-Chapter.html>

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Gring
I just unpacked mine. Looks gorgeous.

Although, I can still perceive the individual pixels if I look close enough.
This is what I expected, because I often hold the iPad at about the same
distance as an iPhone, and the iPad has still lower res (326 vs 264 ppi). It's
not yet this "device that hides its technology in plain sight beyond any human
capability and therefore appears magical". But it's very, very beautiful
anyway.

Here's hoping that Apple will someday produce a 3x display with 396ppi :-D

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gauravk92
They won't, because you wouldn't be able to tell the difference.

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fdkz
A lot of people will be able to tell the difference. For example I routinely
try to read pdf books on my iphone 4 ibooks (without zoom), but it's hard
because there are not enough pixels!

<http://www.displaymate.com/iPad_ShootOut_1.htm>

.. Apple’s definition of a “Retina Display” is actually for 20/20 Vision
(defined as 1 arc-minute visual acuity). However, 20/20 Vision is just 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 almost everyone visual acuity is actually limited by blurring due to
imperfections of 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
true acuity of the Retina. So to be an actual “True Retina Display” a screen
needs at least 573 ppi at 12 inches viewing distance or 458 ppi at 15 inches.
The 326 ppi iPhone 4 is a 20/20 Vision display if it is viewed from 10.5
inches or more. ..

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ugh
Apple doesn't do that kind of stuff. Most people will not be able to see the
pixels (at their comfortable viewing distances). That’s good enough for them
(also considering they are streets ahead of everyone else in the pixels
department).

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veidr
Looks great. The iPad screen really has jumped directly from doodoo to voodoo.

It would be cool to have the e-ink Kindle on that comparison there, too:

<http://www.e-ink-info.com/ipad-slcd-vs-kindle-e-ink-close>

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LukasMathis
Good idea. I've added a picture from a Kindle Keyboard (third gen).

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mladenkovacevic
I love how the e-ink looks up-close. If only the contrast was higher and in
colour. Sadly, I've got a feeling e-ink technology will become extinct.

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LukasMathis
I think there will always be room for e-ink. This afternoon, I took an hour
off to sit on the balcony and read a bit. It was so bright outside that I was
barely able to read anything on the iPad. Switched to the Kindle, worked
perfectly well.

I think it's a technology that fills a niche that LCDs or OLEDs won't fill for
a very long time, if ever.

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kirbysayshi
Any chance you have a Motorola Droid (1st one) hanging around? I'd love to see
how that screen compares. It was near-retina, at least by the look of it, and
I think was AMOLED (since you mentioned the Nexus One).

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Raphael
It's LCD, 265 PPI.

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kirbysayshi
Ah, my mistake, I should have looked first. Honestly, it was a beautiful
screen.

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mwexler
Any suggestions for a good cheap digital microscope? The author doesn't
mention what she or he uses...

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LukasMathis
Mine isn't good, which is why I don't recommend it. But you should be able to
find a reasonably good USB microscope at places like Think Geek, or similar
gadget sites.

~~~
ajross
People have had reasonable success just taping a webcam on top of a used bench
microscope.

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odiroot
Is it only the camera rotation or is Apple switching from BGR to RGB?

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LukasMathis
It's just the camera rotation.

But it's kind of funny, anyway, since the home button is at the bottom of the
screen, so the sub-pixels are arranged top-to-bottom when you hold the iPad
with the home button where it should be.

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odiroot
Does that affect "crispness" of the fonts? Or maybe they reconfigure subpixel
rendering during device rotation.

~~~
LukasMathis
It would affect subpixel rendering of fonts, but I think the iPad doesn't do
any subpixel rendering. Not 100% sure though.

It does create another strange effect, though. Since the screen effectively
redraws sideways if you hold the iPad in portrait, scrolling vertically
quickly makes stuff look a tiny bit distorted; horizontal lines look a bit
slanted (like taking a picture out of a car using a cellphone camera, but much
less so).

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DougBTX
You're right about not doing subpixel anti-aliasing. It would need to change
the direction of the subpixel anti-aliasing on a switch from landscape to
portrait, which would presumably lead to strange visual effects.

~~~
LukasMathis
Right! Good point.

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kimwim42
It looks like Nintendo 3ds screen is made from lego.

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rdl
Would there be a way to demonstrate off-axis viewing capability with the
different screen technologies using the microscope?

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LukasMathis
The microscope only shows a sharp picture at a specific distance; as soon as
you tilt something, most of the picture becomes so blurred that you can't see
much anymore. And there's not enough space between the lens and the focus
point to really tilt the device much, anyway. Sorry!

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gcheong
What is the microscope that you are using?

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LukasMathis
A cheap Bresser. Though I wouldn't recommend buying a low-end microscope, like
the one I use. You should be able to get much better images by investing just
a bit more.

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ricardobeat
If the rows of pixels weren't far apart, visible pixels wouldn't be square.

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jader201
That's not true at all. Maybe for the given shape of the pixels on these
displays, but as a general statement, this is false.

If you have red, green, and blue subpixels that have exactly a 3:1 height-to-
width ratio -- thus forming a perfect 1:1 square -- then you could have zero
black space on all sides, and the pixels would appear perfectly square.

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joshu
Huh! I _JUST_ bought a stereomicroscope. I should try looking.

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nirvana
What's funny about this is just how distorted the pixels are. Ever since I've
understood what displays were (and CRTs before that) I've always imagined this
idealized array of perfectly round, very tightly packed red green and blue
circles as the pixels. Even looking close (not under a microscope) they look
like a grid of squares... not these rectangular things with lots of space
between them.

They seem to be getting more distorted over time. Maybe when they're so small
its less of an issue. I'm surprised at how the red and blue on the kindle fire
are so much bigger than the green. The eye is most sensitive to green... yet
on the PSP Vita the blue seems to be the smallest of the pixels (meaning the
blue pixels will have to put out more light to compensate, or the screen will
have a green/red color cast.)

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smackfu
Are they really distorted though? I wonder if it's an artifact of trying to
image a light source, maybe caused by the display not being perfectly level to
the microscope stage.

I ask because some of the images really do look perfect with sharp edges (the
3DS, the PSP), compared to the blobs of light you see on the other ones.

~~~
LukasMathis
The OpenPandora shot doesn't look sharp because it has an anti-glare coating.
Some of the others may be a bit too bright for the cheap microscope I'm using,
so they're a bit blurry. But mostly, the pixels really do look that way; most
of them aren't rectangular at all.

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niels_olson
Thanks for the pics! Since you have these devices and can simply count up the
number of pixels and divide by the size of the display, would you please
consider photoshopping in scale bars to reflect the length of some unit of
measure?

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LukasMathis
The pictures are less than 1mm wide. I've added a grey bar that approximates
1mm at the same scale at the top of the post to give a sense of the scale.
Does that help?

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idont
Just unpacked mine. Gosh... the screen has an issue... As if there was a
white-led behind the screen. It appears only on bright colors.

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mrleinad
Funny there's no comparison with one of Apple's main competitor phones:
Samsung Galaxy SII/Note. How about adding that?

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LukasMathis
No conspiracy, I just don't have access to these devices. I'll add a Sony
Tablet S when I get around to it, though.

(Update: I've added the Sony Tablet S image.)

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joering2
lukas thanks for it. Any idea about Nexus One -- how come green pixel is so
relatively small. is it just brighter??

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LukasMathis
No, that's how PenTile screens work. There are twice as many green pixels as
red and blue ones (one "visual" pixel is made up of a green and red pixel, or
a green and blue pixel, so there are two sub-pixels per pixel). Thus, the
green pixels are smaller.

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SpiderX
And the reason why is because the human eye is more sensitive to green than
other colors. <http://en.wikipedia.org/wiki/Color_vision>

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jlgosse
I just picked one up and I'm kind of disappointed. There are 3-4 specks of
dirt under the glass, and with the exception of the amazing display, I'm not
sure it's worth the upgrade from the iPad 2. Probably going to return it, and
either get my money back or get a device that has a clean display.

~~~
Cushman
Almost certainly your local Apple store has a stock reserved for
replacements-- you should be able to walk in, show it to them and walk out
with a new device.

