This program randomly generates terrestrial planet textures. It's still a work-in-progress and the code is somewhat messy, but it's definitely usable. Please report any bugs you find on the Issues page!
There are two ways to run the program. On any operating system, you can install Python 3 and the following modules: noise, Pillow, and PySimpleGUI, and run the program from IDLE or the command line. For Windows users, there is also a Windows executable available under "Releases".
The icon for the program is a picture of Kepler-1649c in Celestia (the texture is older than the generator, not made with it). Credit goes to nussun for originally finding the method this program uses to generate planet textures while working on her star texture generator, and Askaniy for originally writing the code that this program uses to generate ice caps.
Here's a screenshot to show what the program looks like:
Update 2024: I don't actively maintain this anymore but I want to ensure it remains functional. Since PySimpleGUI is now a commercial product that's not compatible with open-source projects, I've replaced it with the FreeSimpleGUI fork. Let me know if there are any problems.