Today I was using Brassero on Ubuntu and it said that I needed to install libdvdcss.so.2 (library) in order to make an image file from a DVD. 

To do this, I learned from the Ubuntu support site (https://help.ubuntu.com/community/RestrictedFormats/PlayingDVDs) that all I have to do to get the libdvdcss.so.2 library on my Ubuntu system was to run the following:

sudo apt install libdvd-pkg && sudo dpkg-reconfigure libdvd-pkg

That's all it took and after restarting Brasero I was able to create my disk image without any problem.