在离散数据的基础上补插连续函数，使得这条连续曲线通过全部给定的离散数据点。插值是离散函数逼近的重要方法，利用它可通过函数在有限个点处的取值状况，估算出函数在其他点处的近似值。插值：用来填充图像变换时像素之间的空隙。(On the basis of discrete data, a continuous function is inserted to make the continuous curve pass through all the given discrete data points.