Field extraction method from existing forms transmitted by facsimile

摘要

In this paper, we present a field extraction method in form reading application, for existing forms transmitted by facsimile. In faxed form images, it is difficult to determine field locations exactly due to distortions on the form images. To overcome this problem, exclusive forms have been used. In order to make the field extraction easy, these exclusive forms have restrictions on the style. However, existing forms have various styles and no restrictions. Thus, it is hard to read faxed existing forms. The proposed method corrects the location of fields by estimating the geometric transformation of the form image based on the pairs of corresponding feature-points extracted on the form image and a form model. These feature-points can be extracted from table lines, underlines, character strings, and illustrations on existing forms. Moreover, the method estimates the geometric transformation with robustness for the illegal pairs of corresponding feature-points. These characteristics allow the method to read existing forms transmitted by fax. The experimental results with 50 different types of existing forms reveal the effectiveness of the method.