函数 cvMeanShift 在给定反向投影和初始搜索窗口位置的情况下，用迭代方法寻找目标中心。当搜索窗口中心的移动小于某个给定值时或者函数已经达到最大迭代次数时停止迭代。 函数返回迭代次数。-In the case of a given function cvMeanShift back projection and initial position to the search window, using an iterative method to find the center of the target. When moving the center of the search window is smaller than a given function of the maximum value or the number of iterations has been reached to stop iterating. The function returns the number of iterations.