If you are on linux, you can also use the dd command to copy the contents of the img file to the flash drive. Most, if not all linux distros will boot as is. Although not recently, I have done it this way many times.

$ sudo dd if=</path/to/file> of=/dev/<device> status=progress

If you prefer GUI, then there is most probably a disk utility present on your system, which will do the same. For example I am using gnome and gnome-disks is pre-installed which allows to do the same using the the option "Restore Disk Image..."