Images demonstrating the alignment along the
(a) 2-D projection image taken at a 30°tilt about the x-axis. (b) 1-D projection of (a) onto the x-axis. (c) 1-D projections onto the x-axis of all 2-D projections taken at different tilts about the x-axis. The misalignment is clearly shown in (c), as the 1-D projections should all be nearly the same. (d) Same 1-D projections in (c), shown after alignment is performed along the x-axis.