I just got tipped by an anonymous reader about a nice little trick that will convert iPhone app icons that haven’t been optimized for the iPhone 4 Retina Display to high resolution icons. This will require a jailbroken iPhone and a couple applications.

Step 1: Download iFile from Cydia and Resize-Photo from the App Store.

Step 2: In iFile, navigate to the folder of the application of which you’d like to optimize the icon. The application folder is usually called appname.app.

Step 3: Save the app icon to your camera roll. The app icon size should be 512 x 512.

Step 4: Open Resize-Photo and change the application icon size from 512 x 512 to 114 x 114 and save it.

Step 5: In iFile, navigate to your photos folder and copy the new icon you just resized.

Step 6: Now go back to your app folder and look for the application icon and rename it to something like IconBackUp.png, just in case something goes wrong.

Step 7: Still in the application folder, paste the resized app icon and name it Icon.png, or whatever the app icon was called in the first place.

Step 8: Reboot your iPhone. You should now have a high resolution icon.

Apparently this doesn’t work with every application icon but it should work with most of them.

Pretty nice trick, isn’t it?