You probably know that, using Disk Utility, you can create a disk image from any folder in OS X. Just as with applications you download, items on a disk image won’t be usable on your system until you mount the image. This can be a convenient way to archive older data, as you can compress the image, making it use less space. Items in disk images also aren’t indexed by Spotlight, which can be a good thing if you’ve got a backup folder that contains items with the same name as the originals—double-click the wrong one in Spotlight’s results, and you’ll be working on your backup copy instead of the original. You can also encrypt a disk image, making the data it contains safe from prying eyes.
Personally, I use disk images for quite a few things. Classic lives on a compressed disk image on my machine, and I make disk images out of game CDs—some, but not all, games will let you play them with the disk image mounted instead of having the original master CD in the drive. I also keep a FileMaker Pro database of passwords and other sensitive information on an encrypted disk image, so I can travel with it with some degree of security.
Up through OS X 10.2, there was a standalone application called Disk Copy that supported drag-and-drop disk image creation. Just drag the folder you wanted to convert to a disk image onto Disk Copy’s icon, and you’d get an easy-to-use dialog to set the name and options for your new disk image. With the release of 10.3, though, Apple merged Disk Copy into Disk Utility, and this ultra-convenient drag-and-drop tool vanished. Instead, you had to open Disk Utility, then select Image -> New -> Image from Folder, then navigate to the folder you’d like to use for the image. Ugh.
When 10.4 came out, I didn’t even think to revisit the process to see if anything had changed. Nor, it seems, did anyone else, for I hadn’t heard a peep about it since Tiger’s release. Until recently, that is, when a macosxhints reader submitted a tip—drag-and-drop disk image creation has returned to Disk Utility.
Just drag your folder onto the Disk Utility application icon—whether that’s in the Dock, the Sidebar, the Toolbar, or just in the Finder itself. Disk Utility will launch, displaying the image creation dialog. Set the type of image you’d like to create, and whether you’d like to encrypt it, and you’re set. Seldom do we see a feature removed from OS X make a return in a future version; it’s nice to see an exception in this case.