FIG. 2.

Intermediate results of the moving ball experiment (all ten phases): (a-1)–(a-3): the difference images $F\left(P{f}_i^{\left(k\right)}-c\left(g_i\right)\right)$ after 1, 2, and 3 iterations. Display window: [−500, 500] HU; (b-1)–(b-3): s_i image after 1, 2, and 3 iterations. Display window: [−1000, 250] HU. In each subfigure, the upper and the bottom rows show the transverse and the sagittal view, respectively.