Install gifsicle by entering the following commands in the terminal:
sudo apt update sudo apt install gifsicle
Description:
Tool for manipulating GIF images
This is a tool for manipulating GIF image files. It has good support for transparency and colormap manipulation, simple image transformations (cropping, flipping), and creating, deconstructing, and editing GIF animations, which it can also optimize for space.
Homepage: http://www.lcdf.org/gifsicle/
Version: 1.91-2
Section: universe/graphics