How can I define the rectangle including the surfPoints object on the image?

I have a grayscale image I want to extract the regions of interest using detectSURFFeatures(). Using this function I get a surfPoints object.

by displaying this object on the image I get circles as regions of interest.

For my case I want the rectangular areas encompassing these circles.

To be more clear i have a image 1:

I want to extract Region of Interest (ROI) using : detectSURFFeatures(), we obtain the image

if you can see we have circular region, and for my case i want the rectangular ROI that contains the circular region :