Calculations of HREM image intensity using Monte Carlo integration

We have developed a numerical approach for the accurate and efficient calculation of HREM image intensity formed using a partially coherent source. The approach is based on Monte Carlo integration, and is suitable for use in general image restoration methods using a series of images. The accuracy of this approach is compared with calculations based on the transmission cross coefficient (TCC) for strong scattering objects, as a function of the number of sampling points, defocus, atomic number and specimen thickness. Its efficiency is compared with that of exact TCC calculations based on equally-spaced sampling of the beam divergence and focal spread distributions. The results indicate that the Monte Carlo approach is particularly advantageous for nonlinear image restoration algorithms.