How to Evaluate Mobile Displays


Since this article was first written, an updated version has been posted here. Check it out. A lot has changed.

In my last blog post I talked about the best mobile devices on the market today. This will be the first in a new series of posts that will help you evaluate each part of a smartphone or tablet. Since the display is the main interface to your mobile device, let’s start with it.

Bigger is Better

Three main parameters are used to specify the size and quality of a mobile display:

  1. Screen size measured diagonally in inches
  2. Screen width and height in pixels
  3. Screen density measured in pixels per inch (PPI)

The Samsung Galaxy Note has a much larger screen than the iPhone 4S

Today’s best smartphones have displays which are 4.3″ or larger. The largest screen available on a smartphone in the U.S. today is 4.7″ and can be found on the HTC Titan. Think that’s big? It is, but mobile displays are going to continue to get larger. The Samsung Galaxy Note, which was recently released in Europe, has a 5.3″ screen.  As screens get 6″ or larger, the line between smartphones and tablets will begin to blur and these devices may no longer fit into your pocket. Is it worth it? If you spent lots of time browsing the Web, playing games or working with business documents the answer could be yes.

Screen Size

Pixels (H x W)

Screen Density

Apple iPhone 4S

3.5”

960×640

326 PPI

HTC EVO 3D

4.3”

960×540

256 PPI

HTC Rezound

4.3”

1280×720

342 PPI

HTC Titan

4.7”

800×480

199 PPI

Motorola Atrix

4.0”

960×540

275 PPI

Motorola Droid 2

3.7”

854×480

264 PPI

Motorola Razr

4.3”

960×540

256 PPI

Samsung Galaxy S II

4.3” or 4.52”

800×480

217 PPI

Samsung Galaxy Nexus

4.65”

1280×720

316 PPI

Samsung Galaxy Note

5.3”

1280×800

285 PPI

Chart 1: A comparison of popular smartphone displays

Quality Matters Too!

The HTC Rezound has the highest resolution display available today.

Screen width and height is another popular measurement. Today the best smartphones have 1280×720 pixel displays. The Samsung Galaxy Note has an even larger 1280×800 display. Although the total number of pixels is important, it’s not the best indicator of screen quality. The density of pixels is what really matters.  The higher the pixel density, the more detail a screen can display. Although most people think the iPhone 4S has the highest pixel density, they are wrong. The HTC Rezound has a display with a higher pixel density than the iPhone 4S (342 vs. 326 ppi). Even better screens are on the way. Earlier in the year, Toshiba announced a 4-inch screen with a 367 PPI resolution. Pixel densities are likely to hit at least 386 in 2012.

It’s worth mentioning there is some debate over the ideal pixel density. Steve Jobs once said a device with a pixel density of 300 exceeds the limits of the human retina. However, some photographic experts say that number is too low. They believe the ultimate pixel density is 477 PPI. At that point, it’s said the pixels become invisible to an unaided human eye.

What About Tablets?

Screen resolution is one area where tablets can improve. The best tablets have screen densities below 200 while some smartphones have pixel densities higher than 300. Apple is known for their great displays. How does the iPad 2 compare to Android tablets? Let’s see: The iPad 2 has a 9.7″ screen with 1024×768 pixels. The Motorola Xoom has a 10.1″ screen with 1280×800 pixels. Which is better? The Motorola wins on all three categories: screen size, total number of pixels and screen density (with a pixel density of 160 PPI vs. 132 PPI). If you refer to the chart below, you’ll see there are five other Android tablets with even higher screen densities than the Motorola Xoom. Will we see higher resolution tablet screens next year? Definitely! The Lenovo LePad S2007 will have a 216 PPI display and tablets with 2560×1600 screens will be available some time in 2012. These tablets will have a screen density of at least 300 dpi.

Screen Size

Pixels (W x H)

Screen Density

Amazon Kindle Fire

7.0″

1024×600

169 PPI

Apple iPad 2

9.7″

1024×768

132 PPI

Asus Transformer

10.1″

1280×800

160 PPI

Asus Transformer Prime

10.1″

1280×800

149 PPI

B&N Nook Tablet

7.0″

1024×600

169 PPI

Motorola Droid XYBOARD 8.2

8.2″

1280×800

184 PPI

Motorola Xoom

10.1″

1280×800

160 PPI

OGT Eros Tablet

7.0″

N/A

188 PPI

Samsung Galaxy Tab 7.0

7.0″

1024×600

171 PPI

Samsung Galaxy Tab 10.1

10.1″

1280×800

149 PPI

Chart 2: A comparison of popular tablet displays

That’s Not All

Of course pixel density isn’t the only thing that matters when it comes to screen quality. The color accuracy, color vibrancy, brightness, contrast ratio, black level and viewing angle are important as well. The durability also matters. Gorilla Glass screens are more damage resistant than regular displays. Gorilla Glass 2 screens are on the way, so watch for those.

Well, that wraps up my review of mobile screen technology. In my next post, I’ll write about the heart of every mobile device: Its processor.

Thanks for stopping by.

– Rick

Copyright 2011 Rick Schwartz. All rights reserved. Linking to this article is encouraged.

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About Rick E. Schwartz
Rick Schwartz is blogger from San Diego. You can learn more about Rick by clicking on the "About" tab at the top of this page.

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