Consider you have a CD/DVD at hand and want to create an image (.iso) of the disc so that you can share backup/archive your library. Having inserted the CD/DVD in the drive (assuming you have one), run Disk Utility. After selecting the disk (see image below which was stolen from here ), go to File > New > Disk Image from ".....".From the pop-up window, make sure that DVD/CD Master is selected as the Image Format — that ensures the contents of the disk are completely copied into a resultant .cdr image (Tip: keep the image’s name short and simple so that it can be easily reproduced). After the .cdr image is created, run Terminal and go to the folder where you created the .cdr image. Type the following command hdiutil makehybrid -iso -joliet -o [filename].iso [filename].cdr