Registration of images with small overlap

We address the problem of building a mosaic from uncalibrated images. The key issue in this problem is the registration of the images, i.e., the estimation of the parameters describing the global motion of the brightness pattern between them. Current approaches to global motion estimation avoid preprocessing steps, e.g., feature detection and matching, by inferring the motion parameters directly from the image intensities, through the minimization of the sum of the square error over a fixed window. This window is usually chosen as a large rectangle within the region where it is expected that the original images overlap. Although this leads to good results when the images to register have a large overlap, it often fails when the images exhibit only a small overlap, due to the requirement of choosing a priori a very small window. To overcome this limitation, we propose in this paper an adaptive window.