Originally Posted by "Apple
[" url="/t/151090/supply-of-apples-27-imac-drying-up-as-ivy-bridge-upgrade-awaits#post_2140282"]The iMac will have to be doubled, meaning 5120 x 2880. That's exactly what Apple has done with their two existing retina devices so far.
Actually, the Mac has more freedom in the resolution increase. Today's iMac could easily go from 2560x1440 to 2560x1600 (that's 16:9 to 16:10 like the older iMacs). Then 3200x2000 would be 16:10 or Quad the resolution of the cheap 1600x900 displays (which I never liked) to 3200x1800.
Though, I'm only really talking about screen ratio changes that OS X has more freedom with for obvious reasons.
If the iMac were to use 3200x1800 resolution, I suppose it could do Retina for a 1600x900 sized desktop (too small) and do scaling for larger desktops, but I think people would rather just use the full 3200x1800 (or 3200x2000; 16:10 ratio) than any HiDPI resolutions. So the iMac will have to have at least
1.5 times the linear resolution or 3840x2160 (Quad Full HD) and scale using that resolution.
But ideally, 5120x2880 would be best so it can be Retina at 2560x1440 desktop space, and then perhaps do scaling to even higher desktop spaces if the GPU can handle it! Remember, for it to do a 3200x1800 desktop on a 5120x2880 resolution, it would have to double the screen resolution to 6400x3600 and scale down to the native 5120x2880 display. (Much like the current Retina MacBook Pro doubles a 1920x1200 desktop to 3840x2400 then scales it down to the native 2880x1800 display)
My iMac is set at 3200x1800 with SwitchResX4 right now, and the desktop area is very nice, and it's readable, but the native resolution is still only 2560x1440, so it doesn't look as smooth. But a 3200x1800 sized desktop with a 5120x2880 display would look very nice indeed. I'm sure a desktop GPU can handle 6400x3200 scaling, but not
7680x4320 (Quad Full HD Retina
Desktop – 3840x2160, with 16 times Full HD actual resolution) and scale that down to the native 5120x2880 display.