Aside from being a famous god in Norse mythology, Odin is the name of an application used to flash Samsung firmware onto Galaxy phones and tablets. With this tool, you are able to revert your phone or tablet to vanilla state, and you can also root it using CF-Root or by changing the kernel without recovery.

Creating Odin- or Heimdall-compatible packages from scratch is not easy. But this isn't challenging anymore, as XDA Senior Member hnkotnis wrote a simple guide that explains how to create an Odin-compatible firmware in just a few steps. To crate said firmware, you need a Linux machine or VirtualBox with Ubuntu or another Linux distribution mounted as the operating system.

Hnkotnis presents three situations for creating said packages. The first is RSF format with simg2img support, the second is an image with EXT4 format, and the last is RFS firmware incompatible with simg2img. Making a compatible image requires a few files and UNIX commands, which thankfully are described in detail in the thread.

If you own a Galaxy device and want to make your own pre-rooted firmware, head over to the original thread to learn more.