Figure 2

(a) The intra-operative image interfered with motion artifacts (pointed by the red arrow). The deformed image was transformed by the grid applied to the pre-operative image; (b) Computational time of FPGA-based 3D Demons processed with single-and double-precision, compared with the graphics processing unit (GPU)-based Demons reported in [3] and [4]. Around 100 iterations were required to complete the Demons trials. Only [4] adopted original Demons force computation which involves fewer numbers of gradient operations.