backprojection with "centered_axis = 1" has a small "thresholding" issue

When inspecting visually slices backprojected with varying CoR and centered_axis = 1, it looks like there is a thresholding effect: the slices "moves" in abrupt way.

This does not occur when using centered_axis = 0.

Probably some int(), floor(), ceil() takes place when using centered axis.