- returns a list of tuples, each in format (x, y, w, h)
- where x,y is the top point, and w is the width to the other side, h the height to the other side of the rectangle
- https://towardsdatascience.com/real-time-face-recognition-an-end-to-end-project-b738bb0f7348
- cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
- where (x,y) is the position of the top left corner of the box we want to draw, and the second point is the lower right corner of the box
- https://towardsdatascience.com/real-time-face-recognition-an-end-to-end-project-b738bb0f7348
- (xmin,ymin,boxwidth,boxheight)
- https://stackoverflow.com/questions/49301389/boundingbox-defintion-for-opencv-object-tracking