A morphological subtraction scheme for form analysis

In this paper we propose a method to extract user entered components from various forms that may contain not only ruled lines but also gray-level background. The proposed technique utilizes a pair of form images: i) a blank form image and ii) a filled-in form image. Basically the pair of form images differ only at specific regions of the form reserved for insertion of handwritten (or machine printed) information. A sophisticated technique of inter image subtraction can extract the user entered components. In general, the background patterns of the reference image and sample images are not identical same because of printing and scanning conditions. The authors propose a morphological inter image subtraction to extract handwritten components from the filled-in forms. The user entered components are extracted by this method in a very robust manner.