Tuesday, September 13, 2011

What's Your Resolution?

Today's Tech Gospel is on screen resolution.  No, not the goals we make and break every year... but your screen resolution.

Manufacturers like bragging about higher numbers... specially phone manufacturers.  4", 5", 7" screens... HD, 720p, 1080p... but what do all these numbers REALLY mean?

For example, the iPhone has a 3.5" screen.  Which a lot of the Android phones are already boasting 4" and larger.  Does this make them better?  Not necessarily.  There are 3 sets of numbers that are very confusing, if not misleading, when comparing screens.

First is resolution.  This is the number of dots or pixels you screen has in total.

Second is screen size.  This is the actual physical measurement of your screen taken diagonally from corner to corner.

And third is destiny...er... density.  This is the number of pixels/dots per inch.  Simply referred to as ppi or dpi, it's this last one that makes things a bit confusing.  Larger screens that have lower ppi are cheaper than smaller screens with higher ppi.

Just as a comparison, I've resized a photo to show the exaggerated similarities and differences between these 3 properties.

For the first example, these 2 photos have the same physical screen size: 5.5" screen
 5.5" screen at 25 ppi

5.5" screen at 100 ppi

For the next example, the next two photos have the same resolution: 100 x 100 pixels
100 x 100 resolution on a 5.5" screen

100 x 100 resolution on a 1" screen

For the last example, the two photos show the same ppi / dpi: 100 ppi / dpi
100 ppi on a 5.5" screen

100 ppi on a 1" screen


  1. a very nice comparison John! that's just explains that having HD on a 3" screen doesn't make a big difference. unless you have a HDMI out, and will connect your phone to a flat screen TV (saw the SE guys promoting the new Neo, Mini, Mini Pro, and Ray do just that).

  2. I don't think the ray has hdmi out, I could be wrong. As far as high ppi is concerned, it may not be a big deal, but it does make the photo look clearer, like Apple's Retina Display. You can hardly see the pixels at all. The Xperia ray has pip close to the iPhone 4, and identical resolution to the arc.


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