ImageMagick is a library that allows you to do all kinds of image manipulations.
Rmagick is Ruby plugin for ImageMagick.
In this episode we will learn to read, resize, crop images; overlay images above images; overlay text above images.

Rmagick docs: https://github.com/rmagick/rmagick
Episode source code: https://github.com/corsego/90-rmagick-ruby
Blogpost: https://blog.corsego.com/rmagick-activestorage