def defaultBBoxDeltaFun(w):
    """
    When we reduce the width or height of a bounding box, we use this function to compute the deltaX or deltaY
    , which is applied on x1 and x2 or y1 and y2
    
    For instance, for horizontal axis
        x1 = x1 + deltaFun(abs(x1-x2))
        x2 = x2 + deltaFun(abs(x1-x2))
    """
    # "historically, we were doing:
    dx = max(w * 0.066, min(20, w/3))
    #for ABP table RV is doing: dx = max(w * 0.066, min(5, w/3)) , so this function can be defined by the caller.
    return dx