  Aberration corrected scanning transmission electron microscopes (STEM) enable
to determine local strain fields, composition and bonding states at atomic
resolution. The precision to locate atomic columns is often obstructed by scan
artifacts limiting the quantitative interpretation of STEM datasets. Here, a
novel bias-corrected non-rigid registration approach is presented that
compensates for fast and slow scan artifacts in STEM image series. The
bias-correction is responsible for the correction of the slow scan artifacts
and based on a explicit coupling of the deformations of the individual images
in a series via a minimization of the average deformation. This allows to
reduce fast scan noise in an image series and slow scan distortions
simultaneously. The novel approach is tested on synthetic and experimental
images and its implication on atomic resolution strain and elemental mapping is
discussed.
