Image registration using collinear virtual circles

In this paper, we present an improved image registration algorithm based on the virtual circles features. Virtual circles are extracted efficiently by finding the local maxima in the distance transform of the edge maps. Virtual circles are grouped into collinear set to which a line is fitted to determine the direction. The radii of the virtual circles in the group as well as the direction of the fitted line are used in the registration algorithm. The Hausdorff fraction is also used as a similarity measure to determine the optimal transformation. This algorithm can find large translation, rotation, and scale differences between two images. Further more, it has linear complexity in terms of the number of virtual circles extracted.