Trimage is a cross-platform GUI and command-line interface to optimize image files. All image files are losslessy compressed on the highest available compression levels. Trimage gives you various input functions to fit your own workflow: A regular file dialog, dragging and dropping and various command line options.
Installation on Ubuntu and LinuxMint:
For Ubuntu and LinuxMint, open terminal and enter the following commands:
sudo add-apt-repository ppa:kilian/trimage sudo apt-get update sudo apt-get install trimage
For other Linux distros, please check the official website.