Finding Multiple rectnagle from an single object

I have got an maks of some objects, and from which i want to fiind multiple sub rectangles from it it. in this image i have a single object in mask and i have drawn two rectangle on it which is what i wnat to get

[Mathieu NOE]

seems the topic has been already covered many times

Detect all the rectangles in image - MATLAB Answers - MATLAB Central

Detect all rectangles from an image - MATLAB Answers - MATLAB Central

Rectangle Detection in An Image - MATLAB Answers - MATLAB Central

How to detect rectangle in an image then crop it out? - MATLAB Answers - MATLAB Central

matlab - How to detect all the rectangles in an image? - Stack Overflow

and so on...

[kunal]

ok. Thankyou