知乎回答
https://www.zhihu.com/question/34587586
Modulation Transfer Function (MTF)
Modulation Transfer Function, or MTF, is a measurement of an imaging lens’ ability to transfer contrast from the object plane to the image plane at a specific resolution. The object and image planes are the spatial areas where the object and the image preside. The object plane is in front of the imaging system, and the image plane is either in front or behind the imaging system depending on whether the image is real or virtual. MTF is expressed with respect to image resolution (lp/mm) and contrast (%), as seen in Figure 4. Typically, as resolution increases, contrast decreases until a cut-off point, at which the image becomes irresolvable and grey.
