图像的平面微分平方和能够反映图像高频分 量的能量。用计算平面微分平方和的方法在空间域上计算相邻像素亮度差值的平方和，对应于在频率域上计算图像高频分量的能量和，此值越大，图像对焦越准确-Differential square image plane and the image can reflect the energy of high frequency. Computational method of Planar Differential squares calculated in th