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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  • jigglywiggly - Sunday, February 13, 2011 - link

    i spy with my little eyes a 780i motherboard. Reply
  • EvlG - Sunday, February 13, 2011 - link

    Nice writeup! Can you send a SMS from the portal? Or just view/delete? Would be convenient to be able to chat over SMS without having to get the phone out of my pocket Reply
  • CallumS - Sunday, February 13, 2011 - link

    Hi Anand

    Just noticed that you mentioned two different resolutions;
    In the text: "On the front is the 4.0" qHD PenTile LCD screen (960 x 540 resolution)"
    In the table:4" IPS-LCD 800x480

    Can you please confirm/fix? I hope the first one is correct!

    Cheers

    Callum
    Reply
  • Chloiber - Sunday, February 13, 2011 - link

    There is a whole page about the screen... Reply
  • CallumS - Sunday, February 13, 2011 - link

    Yeah sorry I noticed that later. Obviously just the table is wrong.

    Looking forward to this and other mobile's with high resolution displays!
    Reply
  • StormyParis - Sunday, February 13, 2011 - link

    It does seem to make sense to move phones towards the desktop. They are, or will soon be, powerful enough for most uses. However

    - the price is outrageous. I can get a very good netbook or even laptop for less money
    - the whole setup is proprietary. With the accelerated mobile phone upgrade cycle, it means it's money down a very fast drain. A netbook/laptop will be easier to re-use.

    HP's tap to synch approach makes a lot more sense until these two issues are solved, if they ever are.
    Reply
  • Leimi - Sunday, February 13, 2011 - link

    Hi,

    Thanks for this great preview, this phone seems to be a really great device :)
    One question though, do you know if the LED is multi color ? You can test this with Blink (you have to switch off screen after choosing a color). It's on the market : https://market.android.com/details?id=imoblife.bli...

    Thanks
    Reply
  • jcompagner - Sunday, February 13, 2011 - link

    My carrier has no influence on what phone or what software is on that phone at all. I never buy my phone through my carrier, always just on 1 of the many gsm webshops there are over here.

    Most of the time i just buy my phone when ever a phone comes around that i want to have, i don't look at my contract at all (i also could do that but i most of the time don't do that)

    So buy my phone for 600 euro.. then i go to my carrier when my contract ends (when ever that is) and then i ask them what the best sim only contract there is what they can offer me.. (1 or 2 years). Currently the 2 year was the best so what i get was a 25 euro contract per month where i get 40% off over 2 years, and the first 6 months i did get an additional 50% off on top over that.
    So that's the first 6 months 17.5 euro off (105 euro) and then 18 months 10 euro off (180) thats in total 285 euro that i save, so that i only payed for my high end phone 315 euro on a contract of 25 euro.. And i can buy whenever i want a new phone and extend my contract when thats around the corner.. they are not related to each other.
    Reply
  • erwos - Sunday, February 13, 2011 - link

    They apparently want $500 for the laptop dock and $130 for the desktop dock, not to mention tethering charges WHEN YOU ARE NOT TETHERING.

    It's completely absurd, and is probably the first time I've actually started wishing for carrier subsidies to be outlawed, as they are in some countries.
    Reply
  • svengalis - Sunday, February 13, 2011 - link

    Nope it can't mirror. This is why the Optimus 2x is better to me. It does TRUE mirroring of the WHOLE UI so no need for this silly laptop dock when I can buy a cheap laptop and do basically the same thing for FREE. Reply

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