http://blog.jasonding.top/2014/10/14/Machine%20Learning/%E3%80%90%E8%AE%A1%E7%AE%97%E6%9C%BA%E8%A7%86%E8%A7%89%E3%80%91%E5%80%9F%E5%8A%A9%E5%9B%BE%E5%83%8F%E7%9B%B4%E6%96%B9%E5%9B%BE%E6%9D%A5%E6%A3%80%E6%B5%8B%E7%89%B9%E5%AE%9A%E7%89%A9%E2%80%94%E2%80%94MeanShift%E3%80%81CamShift%E7%AE%97%E6%B3%95/