The qHD Screen: A PenTile LCD?

The Atrix 4G ships with what Motorola calls a "quarter HD" resolution screen. Of course by HD Motorola means 1920 x 1080, and by qHD it means 1/4 the total pixel count: 518,400 pixels.

You get these pixels by way of a 4-inch 960 x 540 resolution LCD display. This is almost the same resolution as Apple's Retina Display, albeit on a bigger screen. It's also the highest resolution display on an Android smartphone. Exciting, no?

There's just one downside. Motorola uses a subpixel layout that should be familiar to those of you who follow AMOLED devices: PenTile.

Each pixel in an LCD or AMOLED is actually made up of three subpixels. In most LCDs this subpixel arrangement is RGB (red, green and blue). In order to extend usable life, all AMOLED smartphone displays use what's known as a PenTile subpixel grid. Instead of a RGB layout, you get an array of RRB and GGB pixels. As a result you minimize the number of blue subpixels, which lengthens the life of the display (apparently the blue phosphors are more likely to lose intensity over time than red or green).

 

Update: The image on the left is actually a stripe matrix, not a bayer grid

Brian Klug, our resident smartphone guru, is usually enraged at the sight of PenTile. Ryan Smith, AnandTech GPU Connoisseur, feels the same way. To some users the trick isn't noticeable. I typically fall into that category. AMOLED offers amazing contrast and that usually distracts me from the PenTile grid.

However, I've never encountered a PenTile LCD before.

The qHD display on the Atrix appears to use a PenTile grid. You can tell by this macro shot of the Atrix 4G vs. the iPhone 4:

Apple iPhone 4 LCD

Motorola Atrix 4G PenTile LCD

Note the ordered grid structure of the subpixels in the iPhone 4's display vs. pattern on the Atrix. PenTile is usually most bothersome when reading text - click the images to see them at full resolution.

Personally I was bothered a bit by text rendering (particularly aliased text on zoomed out web pages) on the qHD screen. For the most part, the qHD display was pleasant to look at and its PenTile upbringings didn't bother me.

If you're like our smartphone and GPU editors however, this may be a deal breaker for you on the Atrix.

The only explanation for Motorola choosing to use a PenTile LCD is Motorola wanted to reduce the cost of the display. The AMOLED argument obviously doesn't apply here. Remember Motorola offers double the on-package memory of the LG Optimus 2X (1GB vs. 512MB). A larger, higher resolution screen can't be any cheaper to integrate. Update: Power consumption is another advantage of PenTile and likely significantly contributed to Motorola's desire to go with a PenTile LCD.

PenTile debate aside, brightness and contrast are competitive. The Atrix 4G is a little dimmer than the Optimus 2X at peak brightness, but overall contrast ratio is in a similar ball park. Just as Brian found in his review of the Optimus 2X, the contrast ratio is numerically lower than the iPhone 4 but I found it to be sufficient on the Atrix 4G.

Display Brightness

Display Brightness

Display Contrast

Combined with the higher than normal resolution, I'll say that I'm mostly pleased with the Atrix 4G's display. There is one downside to all of the extra pixels: GPU performance is lower in 3D games that run at native resolution.

The Atrix 4G has 35% more pixels on its screen, which means a heavier workload for the GPU. Given that Motorola integrates the same AP20H Tegra 2 SoC as LG, performance can be lower.

GLBenchmark 2.0 - Egypt

GLBenchmark 2.0 - PRO

I measured a drop of 14 - 17% in GLBenchmark 2. Measurable, but not the end of the world. This actually puts the performance of the GeForce ULV on par with the SGX 540, albeit at a higher resolution. Luckily for Motorola, the number of heavily GPU bound 3D titles on Android is still minimal.

Software: Stable and Blur-ry Performance: Benchmarks & Real World
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  • Shadowmaster625 - Monday, February 14, 2011 - link

    I was confused when I saw that price. Why would anyone pay that? Then it got me wondering... are we not able to simply plug the phone into our own monitor using the appropriate hdmi cable? And then plug in a usb keyboard and mouse? Who needs a even a $190 dock? This article didnt really explain why. I've got 3 usb keyboards and just as many mice laying around. The last thing I want to do is buy another to satisfy their need for revenue. Reply
  • bill4 - Sunday, February 13, 2011 - link

    The whole controversy over pentile matrix just scream of something Apple fanboys kicked up to attack the competition. Here's guessing both of the editors you mentioned carry an iPhone everyday. Was I right? Gee, what a shock. They probably also love the "retina display" even though that was the biggest bunch of marketing hooey ever. For multiple reasons, not least of which scientifically the resolution has to be a good deal higher than 960X640 for the human eye to not be able to make out pixels at the distance the iPhone is actually used.

    The Apple bias is the media is just insane. Almost every single tech editor in the world just happens to have an iPhone as his personal phone, even though it's the worst phone on the market.

    Anyways my point is, NOBODY in the real world cares about this. I have a Captivate, and I NEVER would have suspected any problem with the display if I hadn't read about it, in fact I still didn't know what the problem supposedly was after reading about it!

    I'm afraid I dont know if I can go back from Super Amoled, the off angle viewing is just so good, when I look at my friends Droid X or iPhone, they just look so washed out and terrible. Even though I'm not exactly thrilled with some aspects of Samsung, and was considering picking up an Atrix or Inspire, the sad fact is I seriously am beginning to wonder if I'll ever be able to go back to a regular LCD on a phone now, they just look so bad.
    Reply
  • bill4 - Sunday, February 13, 2011 - link

    ok, maybe not the biggest bunch of marketing hooey ever, but you get the idea. Reply
  • RaLX - Sunday, February 13, 2011 - link

    Well I would say you're the one behaving as a fanboy...

    Fer me the iPhone display (even if the name is marketing) has a superior definition for text and images and thanks to it being IPS technology the colors are more natural and viewing angles are very good for a LCD (even though poorer than AMOLED of course).

    I hated Nexus One fuzzy text and everybody it's entitle to their opinions without having to be called names. I can tell you that there are persons like me that doesn't stand the grilled texture vision of this kind of LCD and even though I could live with that I will avoid it whenever I can.
    Reply
  • jaredtrobinson - Sunday, February 13, 2011 - link

    lol I agree w/ you.. so much rage from that guy :)

    Anand stated clearly it was a matter of preference. I have an OG Droid and friend has a Dinc, girlfriend has a DroidX. I am not a fan on the Dinc when reading text. The TFTs to me just seem much more crisp
    Reply
  • JCheng - Sunday, February 13, 2011 - link

    I personally care about this a lot. I went to the AT&T store to buy a Captivate and was very distracted by the display's flyscreen effect--that was before I ever heard of pentile (which I learned about after getting home and googling what was wrong with these screens).

    To me the effect is NOT subtle and is very annoying, it's a dealbreaker for me. I thought my next phone was going to be the Atrix but looks like it will be Inspire or Galaxy S II instead.
    Reply
  • TareX - Tuesday, February 15, 2011 - link

    Ditto. I was almost sure the Atrix was gonna be my next phone. I mean, LCD PenTile???? Bad call.

    I love SAMOLED PLUS, but I hate Samsung's TouchWiz.
    Reply
  • TheMan876 - Sunday, February 13, 2011 - link

    I'm currently an OG Droid user and I was thinking of getting a Droid BIONIC (almost the same as an Atrix) when it comes out. But this Pentile screen may make me reconsider.

    I was really happy to read that there would be a higher res screen on these phones, but I hate that Pentile matrix whenever I see it on my friend's Galaxy S phone. Bugs the crap out of me and I'm by no means an Apple fanboy.
    Reply
  • bill4 - Sunday, February 13, 2011 - link

    /AntoineDodsonvoice

    How can tech editors actually cover this product and not instantly realize how stupid it is?

    Hmm, well I can hook it to my phone and it's like a real netbook!

    Hey guess what, Wal Mart sells 10.1", Win 7 starter, 160 GB HDD, netbooks for 249 all day every day.

    This laptop dock thingy, that isn't 1/4 as good or powerful as a real netbook,adds $300 to the price...plus I'm not sure but I thought I read somewhere the dock thing is $130 on top of that...but even if it's "only" 300, it makes no sense AT ALL. It's not even more portable.

    The only way this possibly makes sense, is if by using the phone hardware, you save money on the laptop dock thing, aka it was available for say, 99 dollars. Even then it's pretty dicey, as almost everybody probably already has a laptop, and a good portion already own a netbook as well.

    Plus, though it's technically illegal it works fine, with a tether program like PDA net, you can tether (even on an unrooted phone) without paying the extra 20, which you cant do with this dock AFAIK (since, it doesnt run windows to run the PDA client).
    Reply
  • strikeback03 - Monday, February 14, 2011 - link

    Because the idea isn't really really dumb, the price is. Would you rather they ignore it until the inevitable price cuts are announced? Reply

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