  Intrinsic volumes and Minkowski tensors have been used to describe the
geometry of real world objects. This paper presents an estimator that allows to
approximate these quantities from digital images. It is based on a generalized
Steiner formula for Minkowski tensors of sets of positive reach. When the
resolution goes to infinity, the estimator converges to the true value if the
underlying object is a set of positive reach. The underlying algorithm is based
on a simple expression in terms of the cells of a Voronoi decomposition
associated with the image.
