'**SUMMARY**
This function calculates the minimum bounding circle of the blob in the image
as an (x,y,r) tuple
**RETURNS**
An (x,y,r) tuple where (x,y) is the center of the circle and r is the radius
**EXAMPLE**
>>> img = Image("RatMask.png")
>>> blobs = img.findBlobs()
>>> print blobs[-1].boundingCircle()'

def boundingCircle(self):

    try:
        import cv2
    except:
        logger.warning('Unable    to    import    cv2')
        return None
    contour = self.contour()
    points = []
    for pair in contour:
        points.append([[pair[0], pair[1]]])
    points = np.array(points)
    (cen, rad) = cv2.minEnclosingCircle(points)
    return (cen[0], cen[1], rad)
