I have a PDF math paper with graphs of Curvature and Torsion, also centerline curves, which I would like to utilize as NURBS curves.
Image import and placing multiple points to create curves is one option.
Another option is to convert the PNG curves to SVG curves.

Use SVG trace or VectorMagic to convert PNG to SVG.
Import SVG into MoI.
If there is only one PNG curve, the original PNG curve (may/will) appear as pairs of NURBS curves, with a very small separation.
If there are crossing or parly overlapping curves in the original, it will be necessary to clean up the curves in Moi, to get the desired pair of curves, with Trim and Blend.
(The center of Tan_Tan circles will be on the "average" of the two curves.)
Find the average of the pair of curves with Loft of line segment, and find the centermost Iso_Line, which is the Medial curve, (more or less, for relatively uniform initial curves).

https://discourse.mcneel.com/t/finding-the-average-curve-between-two-curves/149668/13

Orient the Nurbs curves to the proper location on the MoI screen.

This is an initial outline.
Offset command does not quite have the correct result.
Maybe there is already some script in MoI?
Keywords include Medial Axis, Equidistance, central curves, voronoi.

- Brian