[Potential bug] Interpolation wrapper appears to use 1-based indexing despite earlier correction

[raj-magesh]

There appears to be a correction for 1-based indexing here (i.e. moving from MATLAB to Python) but the interpolation wrapper here (until line 70) appears to still use 1, even though it's called after the correction is done.

I could be mistaken, but this seems like a bug? If so, happy to send a PR. Doubt it affects anything since it's at the edge of the image though.

[kendrickkay]

Yes, it seems like it is a bug, but it's just a slight mismatch that would really only affect the very edge voxels. Let's see what @iancharest thinks.