Display pixel density: Where 'more' is not necessarily 'better'

Apple's iPad 3 retina display screen already has pixels so small that they human eye can't make them out. Going any denser than this is pointless.

Apple's iPad 3 has a screen density of 264 pixels per inch (PPI), but Google is rumored to be unveiling the Nexus 10 nest week, a tablet that could push the PPI count as high as 299, well beyond what the human eye can make out.

While this number might look impressive on paper, and allows Google to claim a win over Apple and the iPad 3, in the real world it is nothing to get excited about. In fact, unless you hold the screen real close to your face, or you spend time examining it with a magnifying glass, you're not going to be able to tell that it has more pixels per inch than the iPad 3.

There's also a downside to boosting screen density to beyond what the human eye can make out. The tablet's hardware has to pump those pixels to the screen whether your eye can make them out of not, and the system resources used to do this could better be spent doing other things.

Not only do the extra -- and redundant -- pixels put an unnecessary strain on the GPU, the extra load of the screen and GPU zaps battery life at a faster rate, meaning that your tablet will need recharging more often.

All these downsides just so marketing can get one up on Apple.

The bottom line is that when it comes to tablets, anything over 250 PPI is a retina display, and the pixels are too small to be seen individually. Boosting the figure beyond this might look good on the box and in press releases, but in the real world it can have a deleterious effect on performance and battery life.

The iPad mini and the new iPad 4

Image source: Google.