meanshift均值平移跟踪算法中核函数窗宽的自动选取代码，根据目标大小变化核窗宽，使得当目标出现大小变化时准确跟踪到目标中心(Meanshift mean shift tracking algorithm, kernel function window width automatic selection code, according to the target size changes in the width of the nuclear window, so that when the