- iPhone (1st gen, 3G and 3GS): 480x320 ("a half" of iFrame, in width), approx 3.5 inches screen, 160 dpi
- iPhone 4: 960x640 (same as iFrame, in width), 3.5 inches screen, 326 dpi
- iFrame 960x540
- iPad (1st gen): 1024x768, 9.7 inches screen, 132 dpi.
- iMac (21.5 inch) 1920x1080 ("twice" iFrame, both in width and height), 100 dpi
- iMac (27 inch) 2560x1440 ("2.6 times" iFrame, both in width and height), 100+ dpi
iPhone 4 "doubles" the amount of pixels in both directions, resulting in total 4 times more pixels.
In a potential future "retina" iPad this kind of "doubling" would mean 2048x1536, i.e. about 260+ dpi. This is however well under "retina" requirement of 300+ dpi.
The minimum width would have to be around 2.3 times the original iPad width: 2330px. As this is well beyond Full HD resolution (1920x1080), the nearest "match" in the widths is the 27 inch iMac.
So, is Apple really going to the insanely high land also with iPad (2.5 times the original iPad resolution)?
- Retina iPad: 2560x1920, 9.7 inches screen, 330dpi?
At the very least it would be an unlikely bridge between the mobile and desktop pixels. It will be interesting how far Apple really wants to push the total amount of pixels in the "luggable screen size" of an iPad.
Update: Later blogosphere discussion correctly pointed out that "retina" effect is not simply a matter of "300 dpi". It's highly dependent also on the viewing distance. And between iPhone, iPad, laptops and desktop computers, the viewing distance varies greatly.
So what could the next retina displays be like? Tim Ricchuiti has made pretty well-informed guess (quoted below):
