  We present a 3-step registration pipeline for differently stained
histological serial sections that consists of 1) a robust pre-alignment, 2) a
parametric registration computed on coarse resolution images, and 3) an
accurate nonlinear registration. In all three steps the NGF distance measure is
minimized with respect to an increasingly flexible transformation. We apply the
method in the ANHIR image registration challenge and evaluate its performance
on the training data. The presented method is robust (error reduction in 99.6%
of the cases), fast (runtime 4 seconds) and accurate (median relative target
registration error 0.19%).
