It is important to be able to measure the parameters, such as spatial resolution, astigmastism, signal-to-noise ratio, and drift and instability, that characterize the performance of a scanning electron microscope. These quantities can be determined most reliably by a Fourier analysis of digital micrographs from the instrument, recorded under conditions of interest. A program designed to implement all of the necessary steps in an automated manner has been developed as a 'macro' for the popular, and freely available, NIH Image and SCION Image programs.