Select 'This Computer' in the Backups section, and then click 'Back Up Now.' ITunes backs up your entire iPhone, including iOS, to the hard drive.Click the button for your device near the upper-right corner of the iTunes screen, and then click the 'Summary' tab if it isn't already selected.Start iTunes on your computer, and then connect your iPhone to your computer using its sync cable.For beta versions, check the VFDecrypt Keys page instead. Download an iPhone or iPad firmware that matches your simulator version and make sure that there is a VFDecrypt Key by checking the corresponding Build column.Make sure to install the vfdecrypt binary somewhere in your PATH or use the -d option of the the ipsw_decrypt.py script.
You can extract even more artwork if you decrypt and mount an iOS firmware (.ipsw file).
