def find_center_grid(bbox, stride):
    """
    Given a bounding box in its actual dimension and stride,
    find out which grid cell its center is located in
    """
    xmin, ymin, width, height = bbox
    xcenter = xmin+0.5*width
    ycenter = ymin+0.5*height
    
    return int(xcenter//stride), int(ycenter//stride)