Structural features like defects or heterointerfaces in crystals or
amorphous phases give rise to different local patterns in high-resolution
electron micrographs or object wave functions. Pattern recognition
techniques can be used to identify these typical patterns that constitute
the image itself, as was already demonstrated for compositional changes in
isostructural heterostructures, where the patterns within unit cells of
the lattice were analyzed. To extend such analyses to more complex
materials, we examined patterns in small circular areas centered on
intensity maxima of the image. Nonsupervised clustering, namely,
Ward's clustering method, was applied to these patterns. In two
examples, a highly defective ZnMnTe layer on GaAs and a tunnel magneto
resistance device, we demonstrate how typical patterns are identified by
this method and how these results can be used for a further investigation
of the microstructural properties of the sample.