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Display Quality: Colour Gamut

Motorola Xoom: The First Android 3.1 (Honeycomb) Tablet
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Gaming is only good when you have a good LCD to match, but that also holds true for anything you do on a tablet. I don’t like to rely on subjective opinions in order to evaluate the quality of a display, but there is almost no way to benchmark the Xoom's IPS panel. On the desktop, we have programs like CalMan and ColorEyes to test a monitor’s performance, but these programs don’t work on mobile operating systems. Even if they did work, Android doesn’t honor ICC profiles.

No program currently exists to test the performance of a tablet's LCD panel, which is why I spent a few weeks last month creating a custom program. The whole process is a little complex, but briefly, I’m measuring the colour gamut at the display’s native settings (native gamma and white point) with a Spectracal NIST-certified i1Pro.

Motorola Xoom: LCD Color Gamut (iPad 2 in wireframe)

Even though mobile operating systems don't honor ICC colour profiles, native colour management does occur at the hardware level. When a GPU sends 10 different hues of blue to an LCD only capable of displaying three, the LED pixels will display the closest matching colour. So in a way, smartphones and tablets behave as if they’re using relative colorimetric rendering (for more information, read Tom's Hardware Benchmarks Inkjet Printer Paper!).

Tablets seem to offer similar performance as cheaper TN-based LCD monitors. That was an unexpected conclusion from our iPad 2 review. Yet, the Xoom delivers even less colour quality than the iPad 2. It's close, but you lose noticeable highlights in primary colours. Secondary colour performance is more similar, but you still sacrifice a lot of detail in yellow highlights.

Understand that these gamut measurements bear a few assumptions. First, we're disabling dynamic brightness because it doesn’t facilitate an accurate (or reproducible) measurement of the display’s potential. Second, brightness is set to the highest value. If you don't use the same settings, your colour gamut is going to look smaller than what we're showing here.

The Xoom has a slightly better contrast ratio thanks to deeper blacks, but that doesn't translate to better performance. The colour temperature is a little too cool, resulting in a bluish white, while the low gamma distorts colour perception. Understand that gamma doesn't affect black or white performance, but it does affect midtones. If gamma is set too high, they appear too dark. If it's set too low, midtones appear too pale.

Adobe, Apple, and Microsoft all recommend a gamma of 2.2. It's an arbitrary value carried over from the NTSC standard, but it was originally chosen because it allows colours to appear more natural in slightly dim environments. The Xoom's lower gamma value suggests that it's best used in a completely dark environment. Apple sets the gamma on the iPads much closer to 2.2, which is why colours appear less washed-out when you're outdoors and in well-lit spaces.

The Xoom uses a 1280x800 IPS panel with 150 PPI (pixels per inch). That's slightly better than the 1024x768 IPS panel on both iPads (132 PPI). However, under the microscope, we get a slightly different story. The square pixels found in the iPads help achieve good detail, regardless of orientation. The pixel in Xoom’s AUO panel is slightly more rectangular, which means that you get more image detail in landscape mode.

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  • 0 Hide
    chronicbint , 9 July 2011 17:49
    With iOS 5 a lot of the cons(such as notifications) of the iPad mentioned in the article will be improved upon. Android needs to improve drastically.
  • 0 Hide
    Anonymous , 11 July 2011 19:35
    Regarding the 3.1 update, it would have been worth noting that Motorola are really behind the curve in getting non-US tablets updated. It's starting to look like a classic case of the standard Motorola; release early, announce updates, bad rollout of updates, dump hardware and move on to Xoom2.
  • -1 Hide
    aje21 , 11 July 2011 21:55
    Did you mention the Xoom having a 1280x800 display? I don't remember seeing it (only the iPad 1024x768).
  • 0 Hide
    bobharvey , 17 July 2011 01:45
    You say that windows has native file transfer, but Mac does not. What about Linux? I hope you tried it with Linux.

    Your remarks imply it has no USB mass storage mode. Can that really be true? It seems a major omission to me.
  • 0 Hide
    bobharvey , 17 July 2011 01:47
    You criticise the usefulness of the front facing camera because of Skype. Are there no other VOIP clients available for this thing?