Actual diameter of a distorted spherical droplet

[a2015k]

Hello fellow IJ users

I have images of droplets where they are highly deformed (elongated) inside a tapered constriction. I need to estimate (not very accurately, but reasonable so) the diameter of the droplets prior to deformation. Is there an imageJ function which will do this for me?

Attached is a typical example of the kind of images I have.The bright deformed object is the droplet and I need the size (dia) of that droplet when it was spherical. However, in some images the droplets are even more elongated and it gets difficult to fit any shapes on it.

Please let me know if the problem is not clear. Thank you very much. I would really appreciate your help.

- AK