If you’d like to utilize a 27″ iMac or Thunderbolt Display as a Retina test screen, this post is for you.
In the recent past, I’ve been using a MacBook Pro with Retina display and a Thunderbolt Display connected as my primary workstation. The MacBook in that setup served as a “preview” display for anything Retina related being designed.
Since then, I’ve switched to a series of three 27″ iMacs connected together via Thunderbolt, with offers a 7680×1440 canvas to work with. The plan was to use the MacBook Pro with Retina display separately for testing Retina graphics – but jumping between 2 Macs to test graphics soon became a hassle. The solution? Emulate a Retina display on one of the external screens.
If you go to the Display System Preferences and pick the “Scaled” resolution option, you’ll only see the standard resolution choices on a non-Retina display. However, you can enable the HiDPI/Retina resolutions via a simple Terminal command as follows (single line):
sudo defaults write /Library/Preferences/com.apple.windowserver DisplayResolutionEnabled -bool YES
After executing the command, log out and log back in for it to take effect.
Now, when you select the “Scaled” resolution option, you’ll see all of the possible HiDPI choices. For a 27″ iMac or Thunderbolt Display select “1280×720 (HiDPI)” to get a perfectly crisp 2x rendering of all on screen graphics.