Sheet identifying device and method

摘要

A sheet identifying device and method for identifying the kind of sheet or checking whether a sheet is a genuine or counterfeit one correctly without influence of the state of the sheet. Data on the image of a sheet is acquired, and the image data is binarized according to a watermark region extraction threshold. Image data on the watermark region is extracted according to the sheet image data. The watermark region image data is binarized according to a watermark pattern extraction threshold. The center of gravity of the watermark region is calculated on the basis of the watermark region image data. The watermark region image data is divided into divisions using the center of gravity of the watermark region as the origin. From the watermark region image data, image data on a predetermined specific region is extracted. Values of distinctive features such as the center of gravity and area of the watermark pattern included in the specific region image data are extracted. According to the value of distinctive feature, the kind of the sheet is identified and the sheet is authenticated.