Correct acknowledgment for a figure's digital rendering

Question

If I draw a figure freehand, and then ask somebody else to render it digitally, and integrate the resulting product in a publication, what is the correct way of acknowledging this person's work?

Should I mention their name

1. As a co-author,
2. In the acknowledgments,
3. In the caption of the figure ("Digital rendering by Doe, J.")
4. Something else?

Answer 1

Either 2 or 3 (or both) is proper. They haven't likely contributed to the intellectual content of the paper so 1 would not be required or advised. You did that when you drew the figure. Similarly reviewers and copy editors don't become authors.

If they put a lot of work into it, then both 2 and 3 would probably be best. And, for an acknowledgement, make sure you point to the figure if you don't also use a caption.