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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  • evan919 - Sunday, February 13, 2011 - link

    Hi Anand,

    The reason the Atrix 4G (and consequently the Inspire 4G) suffer from UMTS-sh upload speeds is because AT&T requests the handset manufacturer to disable HSUPA. The same thing occured with every smartphone besides the iPhone 4 on AT&Ts network. I have a Captivate that has HSUPA enabled by flashing the modem firmware with an HSUPA enabled firmware. Just a little insight. I'm enjoying the review.

    http://emuneee.com/2011/02/is-att-disabling-hsupa-...
    Reply
  • shabby - Sunday, February 13, 2011 - link

    Those are just pathetic speeds, 4g my ass att. Im getting 6mbps down and 3mbps up on rogers 3g network with my captivate using bells unlocked hspa modem. Reply
  • FrozenAsset - Sunday, February 13, 2011 - link

    Unless I'm missing something, why waste money on a dock? Can you bypass a dock completely?

    Can you not just provide your own keyboard / mouse and attach by USB hub or connect by Bluetooth?

    It comes with it's own HDMI cable, cant you use that to connect to an HDMI monitor or TV and browse the web at the same time without also paying for tethering?

    The dock I have for my Panasonic TV / iPod is a dumb dock, no chip, no software just a place to sit it and connect to the TV. Why would anyone spend that kind of money on something like that?
    Reply
  • Mumrik - Sunday, February 13, 2011 - link

    It's up to you whether you'll take this as a compliment (personally) or an insult (to the site), but Anand, you are by far the best writer at Anandtech. I'm far more likely to read every word of an article if you wrote it, and as I started to read this one I was immediately able to tell that you were the author. Reply
  • SpartanJet - Sunday, February 13, 2011 - link

    On the "The qHD Screen: A Pentile LCD?" you have a thumbnail of both the iPhone LCD and the Atrix LCD unfortunately when you click on the thumbnail they both link to the same picture.

    I'm really interested in this phone but the screen seems like I'd fall into the "it would bug me" group. I pre-ordered this phone now looking at that screen I'm starting to have my doubts. I think the screens are the 2nd most important feature on these smartphones.
    Reply
  • JCheng - Sunday, February 13, 2011 - link

    What's the first most important feature? Reply
  • notposting - Sunday, February 13, 2011 - link

    Hey Anand,

    I thought I remember seeing that the power button doubles as a fingerprint scanner on the Atrix but I didn't see you mention it.

    Interesting perspective on how things work in the technological fields...this may be the first of it's kind but probably won't be the one that really hits that balance of price and performance just yet...nice demonstration unit though.

    Also agree with the other poster...very well written article. :)
    Reply
  • PubicTheHare - Sunday, February 13, 2011 - link

    Anand,

    I didn't see a reference to the bootloader. I know Moto likes to lock it up (Droid X, Droid 2). Any idea if they did it with the Atrix?

    If so, we can assume they will do it with the Bionic (please preview this one, too!).

    Have fun at MWC!
    Reply
  • sid1712 - Monday, February 14, 2011 - link

    Anand, you've written that the OptimuxS2X has 4" Super AMOLED display instead of the IPS LCD that it has.
    Also, it would be great if you would give your opinion on the call quality via the earpiece and the loudspeaker quality. Do the dual microphones improve the call quality significantly ?

    Cheers
    Reply
  • TareX - Tuesday, February 15, 2011 - link

    I'm extremely disappointed with the PenTile LCD.... even Samsung fixed that with the new SAMOLED PLUS displays... I knew there had to be catch with the Atrix 4G.

    I'm even more disappointed with the contrast and brightness... isn't anything competitive with Apple's IPS? I'm starting to believe Apple really does make the best hardware decisions.

    I am disappointed.... I like Motoblur, actually. I would take it over anything LG makes. Sigh.
    Reply

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