A multiresolution image registration procedure using spline pyramids

We present an iterative multiresolution algorithm for the translational and rotational alignment of digital images. An image is represented by an interpolating spline. Coarser versions of this continuous image model are obtained by using spline approximations at various scales (polynomial spline pyramid). We use a coarse-to-fine updating strategy to compute the alignment parameters iteratively, using a variation of the Levenberg-Marquardt non-linear leastsquares optimization method. This approach yields very precise image registration with subpixel accuracy. It is also much faster and more robust than a comparable single-scale implementation, because the resolution of the underlying image model is adapted to the step size of the algorithm.