Those who buy a new Apple computer and move to the Mac OS X desktop platform from Windows would soon notice a disparity of the installation packages used. In Windows, the extension of an executable file is either MSI or EXE, and when it comes to Mac, it is PKG or APP. Some Mac software is also circulated in DMG format, which is actually a mountable disk image extension with inbuilt compression and security features. DMG helps a software vendor to pack several application files and libraries together for easy shipping. When an end-user clicks on a DMG file, it mounts on the system and opens up the read-only, compressed files enclosed. The installer app included in Mac OS X takes up these files and completes the installation. Since DMG is a disk image, it is comparable with ISO and other Windows formats to some extent.
So, what is the scope of a DMG file in Windows?
DMG as an installer package works only in Mac, but then, you know it’s an archive/disk image too. A number of disk burning/archiving applications in Windows support DMG extension so that we can extract or make changes to the contents of a DMG bundle even if a Mac is not readily available.
Nevertheless, most of the people taking a Disk Image to Windows platform search for a method to burn it to bootable DVD. This becomes a necessity when a Mac gets corrupted, and one lose access to/don’t have a Macintosh installer disc, or if someone wants to re-install the latest OS X 10.7 Lion, 10.8 Mountain Lion or 10.9 Mavericks in offline mode. Since Windows PC is common it is easy to get one and manipulate a DMG file to rescue a Mac in dead stage.
Burn DMG file in Windows.
Want to learn how you can create a bootable OS X backup DVD by using Windows tools? Just follow the instructions given in the next video to start with. Requisites for this project is a DMG copy of the OS X downloaded from the Mac App Store, a few software and a DVD.
Our aim is to burn the DMG file (which is not natively supported by Windows) to a Disc with possible workarounds. Burning a DMG file in Windows involves extracting the target disk image (Mountain Lion here) and restoring the resulting file to a DVD using TransMac.
1. Download 7ZIP here: 7zip is one of the best PC freeware for viewing or extracting the contents of a DMG file in Windows. Install 7ZIP and open the original DMG file with it. Search through the archive until you locate InstallESD.DMG- this is the file we are going to write to a DVD.
2. Download TransMac for Windows here. (15-day trial)
3. Run TransMac as an Administrator.
3. Insert a Dual layer DVD (8.5GB) to the disk drive.
4. Restore the InstallESD.DMG to the DVD as described in the video.
5. Restart to find OS X installer DVD in the boot menu.
The procedure is a bit different in OS X 10.9 Mavericks. In 10.9, we have to extract a file called basesystem.DMG, expand it, and manually add a few files to it to create a disk image, and then burn it to a DVD using TransMac. We will update the article once Apple releases the final version of the new OS.
Convert a DMG file to ISO or IMG or NRG
Programs like UltraISO can be used to mount a DMG file to a virtual drive in Windows environments. This enables you to view the internal files inside the disk, exactly like it appears in Mac. UltraISO also hosts a wide variety of tools that let you convert DMG to Windows readable disk image formats like ISO, IMG or NRG, which we could easily edit or modify if required. UltraISO is shareware; still its 30-day trial is more than enough for an average user. The conversion facility offered by UltraISO is demonstrated in the following video.
Apart from this, there is a disk burner module in UltraISO, capable of writing Mac OS X Install Image (InstallESD.DMG) directly to a DVD. UltraISO is the best option if you’re planning for a Hackintosh (run OS X on Windows desktop), and want to make an ISO version of the OS X installer from DMG.
NOTE: If you’re converting a DMG for writing a bootable disc in Windows make sure that it is the correct file we input. When you check the first video, you can see that there are a few more DMG files inside the original OS X Mountain Lion disk image, and we actually have to extract a file called “InstallESD.DMG” before conversion.
If UltraISO is unable to convert your DMG file, you can try DMG2IMG as an alternative.
Download DMG2IMG here, and extract the files to a folder.
Right-click on the “InstallESD.DMG” file you’ve extracted. In the context menu that opens up, select “open with”–>explorer–>DMG2IMG folder and point it to the executable. You will then see a command line conversion window if the DMG file is compatible and an IMG file in the same folder, a few seconds later. This application will return an IMG file of 0KB size if the input is not in suggested specs, that when it has more DMG files inside it. If you face this error, open it using 7zip and look inside the folders for a non-extractable DMG file.