Automatic Corresponding Control Points Selection for Historical Document Image Registration

Image registration is crucial for various image analysis tasks. In particular, most approaches to correction of bleed-through distortion on handwritten document images require the recto image and the verso image to be precisely registered. In this paper, we present a fully automatic method which detects specific number of corresponding control points from historical documents for the purpose of registration. First, candidate points are located by inspecting the gradient direction maps of document images. Corresponding control points are selected based on a dissimilarity metric that incorporates image intensity, gradient magnitude, gradient orientation and displacement. To improve the quality of the detected control points, median filers and consistency checking are applied to correct mismatches. Experiments on real historical document images have shown encouraging results and further improvements can be made by exploiting more sophisticated similarity metric tailored to historical documents´ characteristics.