Auto Adjust is a universal application and has been since the iPad came out, but I wanted to see how it would look on the iPad’s Retina display in “2X” mode.

The good news is that iPhone apps finally render at their own retina resolution. The bad news is that that’s still less than half of the iPad’s native resolution. iOS 5.1 when not on a retina display still shows these apps at 480×320.

Click for full size:

Auto Adjust running in 2X mode on a retina iPad

Although some elements are scaled using bilinear filtering, you can see the letters in the UIToolBar are nearest neighbor (pixel doubling). Checking with iDecorate showed similar inconsistencies of what gets scaled nicely and what doesn’t.

iDecorate running in 2X mode on a retina iPad

But there is one more piece of info worth noting: the background images for iDecorate are 1920×1280, and it appears the full sized image is being used rather than being scaled down to 960×640 and then scaled back up.

None of this concerns my apps because I write Universal binaries, but it matters for people who refuse to pay for HD versions (or for apps that lack Universal versions – I’m looking at you every speed test app ever).