Testing shows that the Apple iPad 2 surpasses other contenders in display quality, but it still has room for improvement.
The first thing you notice about a tablet is its display. Even when a tablet is powered down, its display is what jumps out first, since the screen is the most dominant part. The quality of the display is a critical component of a tablet, just as image quality is essential to any screen, be it for a laptop, a monitor, a smartphone, or even an HDTV.
I've had dozens of tablets cross my desk, and their display quality has varied dramatically. When I look at a tablet's display quality, I judge it on a number of criteria: brightness, color accuracy, contrast, and image clarity. The last point is a tricky one, as it covers image sharpness and detail as well as text sharpness, areas that can be influenced by how well a mobile operating system renders those elements in software.
Rewind to the debut of the first Android 3.0 Honeycomb tablets--those early models running Android 3.0 all suffered from a bug that caused digital images to render improperly in Google's Gallery app, the default program for viewing pictures. Images looked fuzzy, with little detail. Google quietly fixed the bug later, in Android 3.1; nevertheless, image reproduction could be better, and the Gallery still natively displays images in just 16-bit color.
So where does that leave the discerning buyer hoping to get the best tablet display possible? To find out, the PCWorld Labs lined up eight tablets and compared their image quality side by side. Our testing is ongoing, and we will fold the results into our ratings for tablets in the future. Right now, we can offer a glimpse of our early findings.
Tablet Displays Tested
This first pass of our subjective testing focused on images and color, not text. Our jury reviewed four identical images on the eight tablets, with brightness settings on max for all. What we found was a bit surprising, in that the images varied dramatically and noticeably. During my earlier hands-on testing, in which I compared all comers with the standard-bearer, Apple's iPad 2, I had noticed some differences and issues--but to see the variety in a lineup was something else altogether.
In our comparison were the Acer Iconia Tab A500, Apple iPad 2, Asus Eee Pad Transformer TF101, HTC Flyer, Motorola Xoom, Samsung Galaxy Tab 10.1, Samsung Galaxy Tab Wi-Fi (7-inch), and T-Mobile G-Slate. Many of the tablets we looked at run Android 3.0; only two of the five 10.1-inchers, the Motorola Xoom and the Samsung Galaxy Tab 10.1, had Android 3.1. (Click the chart below to view it at full size.)
The Apple iPad 2 was clearly and consistently the leader of the pack; it stumbled only on a photo with a variety of skin tones and colors, failing to strike the right balance. In another shot, the iPad 2 had the best color balance and accuracy, and it showed the best distribution of colors on our grayscale and color-bar images.
The two next-best displays were not on flagship Android Honeycomb tablets, but on tablets running Android 2.2 and 2.3--the Samsung Galaxy Tab Wi-Fi and the HTC Flyer, respectively. Each of these models did particularly well with skin tones and color balance in actual photos, although neither one quite nailed the balance in our color-bar shot.
None of the Android 3.x tablets we tested could compete with the iPad 2, or with the Android 2.x tablets. In our tests, the Samsung Galaxy Tab 10.1 did better overall than its next-closest competitor, the Motorola Xoom. But the Tab blew out colors with oversaturation, and crushed shades of black; this tendency was clear in our test photos as well as in the grayscale and color-bar images.
The Xoom's display never particularly impressed me, but in the end it did better on balance than some of the other Android tablets we tested. It suffered from washed-out skin tones, poor handling of brown hues, and a lack of sharpness--even with the Android 3.1 update. The touchscreen grid was evident on the Xoom, too.
Falling in between were the T-Mobile G-Slate and the Asus Eee Pad Transformer TF101. The results from these two tablets were close, although in our detail shot the G-Slate appeared to have slightly better detail and color balance despite its tendency toward a greenish cast. The Transformer offered a great angle of view (which we expected given that it has an IPS display), and it did a reasonable job of reproducing browns, but its reproduction of reds was off-base.
The Acer Iconia Tab A500 consistently landed at the bottom. As with the Xoom, you can see the touch-panel grid on the Iconia Tab, but in this case it's clearly visible pretty much any way you hold the tablet, making the grid a viewing annoyance at best and a deterrent at worst. Running the Android 3.1 update, the Iconia Tab struggled with reproducing skin tones and browns, and it tended to give a slightly bluish tint to images.
Common Tablet-Display Issues and Needs
As I mentioned at the outset, some of the questions surrounding displays are hard to pin down. So much about how an image looks can be tweaked in software. Even more can happen in subpixel rendering, or in aggressive software algorithms aimed at optimizing the image (I've seen some hints of how this approach can work in the upcoming Toshiba Thrive). But some issues, such as angle of view and high reflectivity, are physical in nature, and as a result no software fix can address them.
All of the tablets we've seen, including the ones with IPS displays, have angle-of-view limitations--some are worse than others. And all of them have an air gap between the glass and the LCD layer beneath; that gap increases reflectivity, which causes the mirror effect that makes tablets terrible for use in bright sunlight. (The sole exception is not marketed primarily as a tablet: Barnes & Noble's Nook Color employs a bonding process that minimizes, but doesn't eliminate, reflections.)
Our look at tablet displays is a subjective experience, putting real images to a real-world test. Raymond Soneira of DisplayMate also published findings today from quantitative-measurement tests of the iPad 2, Motorola Xoom, and Asus Transformer displays. His findings delve deep, and echo much of what we've seen in our lab subjectives. In his tests, the iPad 2 was on top, with the Transformer besting the Xoom. I'd wager that the result came in part from the Transformer's Android 3.1 update; for our early wave of tests, we still had the original software on the Transformer.
We're in the process of revisiting our testing, with the latest Android and firmware updates applied where appropriate. Stay tuned for our second wave of tablet-display tests in July.
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