ISO Master can read .ISO files (ISO9660, Joliet, RockRidge, and El Torito), most .NRG files, and some single-track .MDF files; it can save only as .ISO.
You can use isomaster to:
--- add files to an image
--- extract files from an image
--- delete files from an image
Install ISOMaster in Ubuntu 16.04
Open the terminal and run the following command
sudo apt-get install isomaster