In 16 bit grayscale, resolutions as a power of 2.
I understand you might not be working on this project anymore. I made a fork of this here https://bitbucket.org/javoire/lithosphere but I'm struggling to make it run since (my guess) you used an older version of Pyglet.
I did some minor modifications to your other libraries https://bitbucket.org/javoire/halogen and https://bitbucket.org/javoire/gletools to make Lithosphere at least launch, but I there's a ton of other incompatibilities with Pyglet to be solved until it'll work right.
The reason I'm interested in Lithosphere is that it seems like an amazing open source tool to create terrains (it does exactly what is expected, easy and quick to use and good UI), and I'm into indie game development so I think the community would need the addition of this tool to other open source tools (like Blender etc). There's no good option for open source terrain generating software atm and this in my opinion would be a very good candidate to fill that spot.