Figure 3: Visual comparison of the various registration algorithms. The cost functions for FLIRT include CR (a), NCC (b), MI (c), and NMI (d). The cost functions for MIPAV include CR (a), NCC (b), and NMI (c). The top middle image (MAR, short for MAR-GUI) was the only registration that was able to successfully overlap all three fiducial markers, whereas the other registrations were unable to overlap all of the fiducial markers, in particular, the top fiducial marker.