A pattern recognition method for lattice distortion measurement from HRTEM images

The idea of the method is to analyse a crystal lattice by creating a grid of quadrilaterals corresponding to repeated cells that are visible in the image. This approach combines image processing elements with a continuum field theory, to create a distortion-independent similarity measure that is used to select the most appropriate among possible lattice configurations. Subsequently, displacement and distortion fields are computed from individual cell positions. The method allows one to obtain these fields even for images where a periodic cell does not necessarily appear as a single dot of intensity in a high-resolution transmission electron microscopy (HRTEM) image, which results in a lower accuracy of commonly used approaches, namely geometric phase and peak finding. The results obtained from this method are verified quantitatively by comparison with known distortion tensor distributions and Burgers vector values on both simulated and real images.