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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  • xaml - Tuesday, February 15, 2011 - link

    But can it run Crysis? Reply
  • Weedkillers2 - Wednesday, February 16, 2011 - link

    Hiya

    Due to initial reviews iv read the concept of the dock / webtop is good but its a bit slow...

    Mabye it would be in Motorola's interest to create an Overcloking Application when the device is running off external Power such as

    The Laptop Dock or the HD Dock

    this would boost its peformance when mains connected and make the device more appealing in thouse situations to no realy change of the product required.

    (obviously use at own risk feture or atleast different levels of over clok use at own risk)

    Dylan
    Reply
  • synaesthetic - Wednesday, February 16, 2011 - link

    Until smartphones have modular and universal OS capability, they won't replace computers.

    When you can just hop over to Google's website and download a new, universal version of Android, and then hop on over to Motorola's website to download your device's appropriate drivers, THAT will be the moment that smartphones can truly attempt to replace PCs in the mainstream market.

    Until that happens, walled-garden systems, lack of speedy updates and OS fragmentation will keep them in their current niche.

    Oh, and they should *ship* with root access easily enabled, just like a computer. No exploits or hacks required, a simple flipping of a switch in the OS to enable superuser permissions.
    Reply
  • TareX - Thursday, February 17, 2011 - link

    Can Ananad (or anyone who held the phone) tell me how bad the text "fuzziness" was in the browser, on a zoomed out view? Some reviews said it appeared "pixelated" and unreadable despite of the qHD screen. Reply
  • EMM81 - Saturday, February 19, 2011 - link

    Anand can you give some more detailed impression/images of the Atrix screen. If it really is a pentile matrix it would be an RGBW scheme. This is unfortunate because it is basically like adding a white sub pixel to the existing red, green, and blue sub pixels and calling it twice the resolution. So by my calculation the screen is really ~679x382 if you considered RGBW as one pixel. I would assume that the impression of this screen would therefore be that of a lower resolution than 800x480 and theoretically the white sub pixels would allow it to either be brighter when displaying non color saturated images or to lower the back light and save power. Since your graph clearly shows a lower contrast ratio the only possibility is power savings at the expense of quality. PLEASE correct me if I am wrong but this does seem to be the case. Reply
  • DisplayGeek - Tuesday, February 22, 2011 - link

    You are indeed wrong and here's why:

    http://www.nouvoyance.com/files/pdf/measuring-pent...

    Counting the number of subpixels, when using a system that uses both subpixel rendering and metamer rendering (where one uses the fact that white can be produced by both a single W and the combination of RGB) allows the display to use only two subpixels per pixel *on average*.

    Yes, the RGBW system allows the power to be cut roughly in half.

    The full on white to full off black contrast ratio is dependent upon the LCD technology itself, how much light leakage occurs in the dark states. It has nothing to do with the subpixel arrangement or color filter system, or its mode of operation. Though, the Dynamic Backlight Control does improve the contrast when dark images are shown, as reducing the backlight brightness makes the darkest states darker, while maintaining the brightness of the intermediate grey states. But that wasn't tested here.
    Reply
  • arth2910 - Monday, February 21, 2011 - link

    The Meizu M9 actually has the highest resolution of available android smartphones (matching that of the iPhone 4's). Acer's Iconia Smart also appears to be touting 1024x480. Reply
  • eawortman - Friday, March 04, 2011 - link

    Is there still a full review coming? Reply
  • santro652 - Saturday, March 05, 2011 - link

    Hi Anand,
    I am planning to get the Atrix carrier free version from USA, can anyone tell me if this phone will work in India or is there any unlocking required after taking a carrier free version. Please. Thanks in advance.. If anyone else knows the reply please let me know ASAP, Please
    Reply
  • Kawboy12R - Thursday, April 28, 2011 - link

    Looks like the full review got derailed somehow. I'd love to see some AT reviewage though. Reply

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