Once you’ve backed up the contents of a hard disk or CD-ROM to a disk image, how can you restore the files?
Double-click the .dmg file to mount it, then locate the files using the Finder. If a large disk image is split into multiple .dmg and .dmgpart files, move or copy them all into a single folder before trying to mount the .dmg.
Tip: If you have many .dmg files, you can use a utility such as CDFinder to catalog them so that you can easily find which .dmg contains the files that you’re looking for.
Open the Disk Utility program in the Utilities folder of the Applications folder.
Tip: You can also access Disk Utility by booting from your Mac OS X installation CD/DVD; that way, you can restore your drive without first having to install Mac OS X.
Choose Scan Image for Restore… from Disk Utility’s Images menu and select the disk image file. If you used DropDMG’s Optimize for restores option when creating the backup, you can skip this step.
Select the target drive in the list at the left side of the main Disk Utility window.
Click on the Restore tab. Drag the image file onto the Source field, and then drag the target disk from the list to the Destination field.
When you click the Restore button, Disk Utility will erase the target drive and replace its contents with an exact copy of the drive that the image was created from. If the original drive was bootable, the restored drive will be, too.