This is an image registration plug-in for Gimp. The plug-in can be used as a Gimp tool for automatic alignment of similar, but displaced images. A typical use is the alignment of images in HDR methods before combining their intensities.
I used it for alignment of astronomical images; it has some difficulties with stars, which appear almost point like and have no extended structures. However it works pretty well and superposition of several exposure is astonishing. Knowing how to use it efficiently is now that easy. So, it's a GREAT work, but I would recommend a more active discussion forum to help people starting. btw, I produces RPMS and source RPMS for Fedora systems for easy installation; are you interested in? Mathieu, researcher in astronomy.
One of my most valued plug-ins for GIMP. In the right situation this plug-in can save you a large amount of time while also having much more accurate results than what can ever be achieved with only your hand & eyes. I definitely recommend it.