The darktable project welcomes contributions:
- Code
- Documentation
- Testing (and any backtraces if you happpen to crash darktable)
- Translations
- Camera profiles.
- Tutorials, screencasts, etc.
See the darktable development page for more information.
Before you spend a lot of time working on a new feature, it's always best to discuss your proposed changes with us first. The best place to do that is in our IRC channel on irc.freenode.net, channel #darktable or the development mailing list, see here for more information. This will dramatically improve your chances of having your code merged, especially if we think you'll hang around to maintain it.