- A convenient form with which to quantify image degradation due to motion and vibration is the optical transfer function (OTF). We introduce a new method of calculating the OTF for image blur caused by arbitrary motion. Previous methods, except for a few specific types of motion, were numerical rather then analytical. This new method make it possible to obtain analytical expressions for the OTF, deriving from any kind of motion, by means of the statistical moments of the motion function. An analytical OTF expression is derived for sinusoidal vibrations. An example of the implementation of the method in restoration of images blurred randomly by low-frequency vibration is presented.