调制传递函数（MTF）被广泛用于定性和定量地描述一个光学成像系统成像本领。事实上有多种不同的方法可以获取成像系统的MTF。提出了一种新型线扩展函数（LSF）拟合模型用于计算MTF。函数模型中的各个参数可以使用非线性最小二乘法来确定。与以前提出的函数模型相比，不论在何种噪声条件下，该函数模型的MTF计算结果总与参考值最为接近。使用该函数模型计算退化图像的MTF，并将其应用于降质图像的复原，实验结果证明了计算值的可靠性和用于图像复原时的有效性。

The modulation transfer function (MTF) has been widely used to characterize and quantify the spatial resolution of a linear and space-invariant imaging system. Various methods have been proposed to determine the MTF of an imaging system. A new analytical line spread function (LSF) fitting model to calculate the MTF is proposed. The LSF parameters are confirmed by means of a nonlinear least-square fitting technique. Compared with previous models, the MTF estimate based on proposed model shows the lowest error in the presence of different noise. A practical application of MTF measurement in degraded image restoration also validates the accuracy of proposed method.