Apple Software Restore (ASR) is a command line utility in Mac OS X.
The utility is used to clone Macs, but applying a DMG file to a selected volume or a mounting point within a full file system.
ASR can restore images in two different ways. The first is a "file-by-file" copy mode and the second is an image copy.
The second method is obviously faster but will require the DMG to be checksummed, and re-arranged if necessary.
Apple's Disk Utility uses ASR as a background process when restoring.