In making quantitative measurements using electron micrographs we must regard the electron microscope as being an information channel. The information about the object is both in some way transformed by the image forming process, and information is lost through the existence of a spatial resolution limit and the addition of noise. To make quantitative measurements, we need to take account of all these effects.
Great progress has been made in making quantitative measurements from high-resolution transmission electron microscope (HRTEM) images (for example see Ref. ). However, the simulation of HRTEM images requires a full dynamical electron scattering calculation in addition to computing the effects of the objective lens aberrations. Although such calculations can provide excellent agreement with experimental data, the calculation times involved restrict the number of trial structure models that can be used, with the danger that such trial and error methods might miss the true object solution.