I often to backups before big changes to my system, or just hacks that I am not sure if it will blow up my system.
Sometimes I run Unity from time to time and I am not sure if other back systems run in a similar fashion, but I assume they do. The program I used for this particular back up was Gnome Disks. Since I am normally a KDE user I had to figure out how to mount the img file without being in a GTK environment.
Fourtantely it is fairly easy to do. Just three commands.
This mounts the image.
sudo losetup -f -P DiskImage.img
This displays the devices partition layout and assignments.
This mounts the partition table. Make sure you change /dev/loop0p7 to your device.
sudo mount /dev/loop0p7 /mnt/