Please check this image. Is it possible to count the number of drops present?
I can't see the image. Are you sure the link is correct? In general, to find circles, use imfindcircle(). There is a demo in the help:
Measuring the Radius of a Roll of Tape
This example shows how to measure the radius of a roll of tape, which is partially obscured by the tape dispenser. Utilize imfindcircles to accomplish this task