Niftilib has been developed by members of the NIFTI DFWG and volunteers in the
neuroimaging community and serves as a reference implementation of the nifti-1
file format.

http://nifti.nimh.nih.gov/

Nifticlib code is released into the public domain, developers are encouraged to
incorporate niftilib code into their applications, and, to contribute changes
and enhancements to niftilib.