Being the sheet and its authentic distinction manner for forgery prevention and the sheet for forgery prevention

摘要

PROBLEM TO BE SOLVED: To obtain a sheet for forgery prevention which is very difficult to forge, a truth and falsehood discriminating method capable of easily discriminating its truth or falsehood and a truth and falsehood discriminating device capable of easily discriminating the truth and falsehood. SOLUTION: This device forms a watermark that is invisible and meaningful in the case of manufacturing a sheet for forgery prevention, obtains a grayscale picture having variable density gradation by picking up the image of the watermark under transmitted light, obtains a transformed image by performing image transformation of the grayscale picture by an image transforming device and can easily discriminate whether a sheet to be inspected is true or false by comparing the transformed image with a transformed image obtained by the sheet to be inspected.