pngcrush is a free and open-source command-line utility for
optimizing PNG image files. It reduces the size of the file losslessly;
that is, the resulting "crushed" image will have the same quality as the
source image.
Enable snaps on elementary OS and install pngcrush
Snaps are applications packaged with all their dependencies to run on all popular Linux distributions from a single build. They update automatically and roll back gracefully.
Snaps are discoverable and installable from the Snap Store, an app store with an audience of millions.
Enable snapd
Snap can be installed on elementary OS from the command line. Open Terminal from the Applications launcher and type the following:
sudo apt update
sudo apt install snapd
Either log out and back in again, or restart your system, to ensure snap’s paths are updated correctly.
Install pngcrush
To install pngcrush, simply use the following command: