Retina displays - and, more recently, Retina HD displays - are often mentioned in discussions of Apple products. In this beginner's guide to Retina and Retina HD, we explain the definition of a Retina display, the difference between Retina and Retina HD displays, which iPads, iPhones, iPods, Macs and MacBooks have Retina or Retina HD displays, their pros and cons, the premium you are likely to pay for Retina screens where non-Retina options are available and whether (in our opinion) they are worth the extra money.
What's a Retina display? Or rather, what's the precise definition of a Retina display?
A Retina display is more of a proprietary, Apple-specific marketing term than a precise technical term, but there is a definition: it refers to a screen on a computing device that has a high enough pixel density that the human eye can't make out individual pixels - or a general 'pixellation' effect - at all. In other words, the human eye is scientifically incapable of telling the difference between a photo of a painting shown on a Retina display, and the painting itself - in theory, anyway.
As mentioned, Retina displays are proprietary to Apple. So while a rival company could produce a screen to the same specs, it wouldn't be referred to with the same word. It's an Apple-trademarked term.
Retina display: iPad Air
My eye won't be fooled.
Perhaps not. Apple was able to wheel out some scientific backing for its claims when launching the Retina display, but it has been suggested that people with better than 20/20 vision might be able to pick out the pixels.
Furthermore, Apple's later launching of devices with better-than-Retina resolution (under the term 'Retina HD', which we'll discuss in due course) rather undermines its claim that Retina is as sharp as the human eye can make out.
What resolution does a Retina display have?
That varies. Screen resolutions are given in the format '[number of pixels] x [number pf pixels', but the key factor in classifying a screen as Retina is pixel density, not the overall number of pixels. This makes sense, if you think about it: if you spread the same number of pixels across a larger screen, it will obviously be easier for the eye to pick out individual pixels. Pixel density is given as a single figure, measured in pixels per inch, or ppi.
And even in terms of pixel density there isn't a single figure that qualifies as Retina, since the equation also takes into account the distance of the screen from the eye. The required pixel density for each type of computing device - smartphone, tablet, laptop, desktop PC - is calculated based on a typical viewing distance. If you hold your iPad right up next to your face (you shouldn't do that, by the way) you may find that you can pick out pixels after all, because you are no longer using the device at the expected typical disance. Don't expect a refund.
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