FMRIB Software Library software (FSL)

FSL is a package for analysis of FMRI, structural, and diffusion data. FSL is written by the image analysis group at the Oxford centre for Functional Magnetic Resonance Imaging of the Brain. The package is mostly C or C++ with a Tcl/Tk GUI, and has a dual license - open source and free for academic use, but commercial use requires a paid license.