dmg2iso

dmg2iso is a standard command-line utility whose sole purpose is to create ISO images from compressed (z-lib) DMG files. It doesn't come equipped with any configuration parameters, making it ideal even for less experienced users.
While most users prefer working with graphical interfaces to perform a simple task like conversion, most of them would rather deal with Command Prompt dialogs, since a few written lines are enough to perform a job in no time.
Furthermore, command-line tools do not require installation, so they can be run from any location on the hard disk, and on any machine without prior installers, from USB flash drives.
Once you launch a Command Prompt dialog and run dmg2iso.exe, all you have to do is specify the source file's name and format (provided that it exists in the same directory as the utility), along with the output file name and extension.
ISO images are automatically delivers to the same location as the source items, and this option cannot be changed. Unfortunately, batch processing is not supported, so you cannot convert more than one image file at the same time.
As we have expected, dmg2iso is very low-demanding when it comes to CPU and RAM, so it doesn't slow down system performance or interrupt user activity. It finishes a conversion job rapidly, depending on the size of the source file. No error dialogs have been shown in our tests, and the tool did not hang or crash. Too bad that dmg2iso has not been updated for a long time.