Thanks for the rating. I guess I would still call this an intensity-based segmentation, unless you are extracting properties of the regions (centers, radii) and using some algorithm to match. In this case your intensities are binary-valued, but they're still intensities.
I have 2 images which they contain a circle.
First, I segmented the circle in both images, then apply your registration app to register them.
My question is, what will be the name of my registration?
Since, my images are "black & white", I think I cannot name it "intensity-based", right?