ALIGNING A DISTORTED IMAGE

Disclosed herein is a non-transitory computer readable medium that has stored therein a computer program, wherein the computer program comprises code that, when executed by a computer system, instructs the computer system to perform a method of determining the charging induced distortion of a SEM image, the method comprising: determining, at each of a plurality of locations in a SEM image of at least part of a sample, a deflection of an illuminating charged particle beam caused by a charging of the sample at the location; and determining the charging induced distortion of the SEM image in dependence on the determined deflections at each of the plurality of locations in the SEM image.