"Dissolved" Images (a.k.a LSB with Alpha)
Digital Invinsible Ink Toolkit
This project provides a simple Java-based steganography tool that can hide a message inside a 24-bit colour image so that knowing how it was embedded, or performing statistical analysis, does not make it any easier to find the concealed information. (Related forensics challenge in XmasCTF2019)
https://sourceforge.net/projects/diit/
Stego Toolkit Docker Image by DominicBreuker
A very portable docker image with pre-installed steganography tools for jpegs and png images
https://github.com/DominicBreuker/stego-toolkit
PILLOW (The Python2 name is PIL)
Python Image manipulation Library