We implemented the inverse compositional image alignment framework, initially proposed by Baker & Matthews with an application to facial AAM fitting in mind.
The main variants of the fitting algorithm (simultaneous, project-out, weighted simultaneous) have been implemented. We have used GNU Octave (a libre Matlab clone) as a framework for test and development. Some parts of the algorithm have been implemented in C++ for efficiency purpose.
Update : a new pure C++ version could also be found on the github repository.
The code is released under the terms of the CeCILL free and open source license (Here in french). It is compatible with the GNU GPL license.
Please see the Github project