Originally Posted by Unicron
Wouldn't that "un-Retina" the Retina Display?
It depends on two factors. The PPI and what you say is the average distance from the eyes/face in which you use the device. For instance, a 4" iPhone with the same 960x640 resolution would have a PPI down from 326 to 288, which could still be marketed as accepted definition of Retina Display without being questionable.
An iPad with double the resolution (quadruple the pixels) would still be lower at 264 PPI but could still feasibly be called Retina Display because you place the display farther from your eyes.
Raymond Soneira fudged the math by using 0.6 arcmin which is pretty much the best possible a human could have and considerably better than the 1.0 acrmin of 20/20 that we tend to call "perfect vision". Since 20/20 is the common standard I have no problem going with that for defining this marketing term, but Soneira's vision
, at best. (Yep, puns intended)
PS: 288 PPI for a 4" iPhone is actually 2 more PPI than the minimum PPI of 286 for 20/20 vision at a distance of 12".