This is not possible yet.
The teacher has to look at the answers on the sheets, correct the AMCOpen questions ticking the boxes with a pencil, and scan the sheets afterwards.

Thank your for the prompt answer! I further looked into "DOC-calage.xy" and "capture.sqlite" files. I figured that no positioning info in those files too, although there're extra data in capture.sqlite that I couldn't identify at this point.

As fields like "\namefield" are properly processed with images extracted, I guess it's possible to do the same thing to \AMCOpen. May I suggest this to be implemented as a future feature? I assume it's not too much away from what AMC is designed for.

thx --w.

I guess it's possible to do the same thing to \AMCOpen

Yes: possible but not yet implemented.

May I suggest this to be implemented as a future feature?

Yes: please add a feature request.

Is this feature still considered? I will love to be able to handle open questions for analysis.

I know this is not what you are asking for, but I don't know how you want to grade the open questions. If you are going to grade them within AMC, then I can't help you. However, I have written a set of scripts (in python) that work with AMC to extract pdf files for grading. I then grade them on my tablet. If you are interested in that, let me know. Currently, the software creates a page per open question, so it works better if there is one question per page. However, I hope to improve that.

Certainly if AMC saves the image of the question and response from AMCOpen, that would make things even easier.

Added feature request #446 (http://project.auto-multiple-choice.net/issues/446)