Circle detection without overlapping

Question

I want to do circle detection under the condition that: overlap circles will be count as 1 circle.

Particularly, when I do circle detection and put the letter \"P\" to e

Answer 1

(1) Threshold using OTSU and then adjust the thresh vaule again

(2) Find the external contours on the binary image, filter the contour by area, then find the minClosingCircle.

This is it: