Running ImageJ on Android won't work, because:
- ImageJ 1.x uses AWT, which is not available on Android
- ImageJ2 was built with a separation of concerns in mind (see Architecture page for technical details), but there is no infrastructure in place to ensure that all ImageJ2 APIs are Android-compatible. It would be a feasible project, but potentially a lot of work, to do that.
See this forum thread for further details and discussion.