| 摘要 |
A substrate for a security document such as a banknote, has physically formed therein identification features which are invisible to the eye but are repetitive so as to be detectable, after scanning, by computer. The features may be arranged in a 2D matrix and be spaced at regular intervals over the substrate. The physical features may be formed by embossing, surface treatment of lacquered papers, impregnation, laser treatment or watermarking. The features enable banknote verification and determination of denomination. Reproduction of the document by printing may be inhibited by subjecting the image data signals to an algorithm which serves as a second control to downgrade or inhibit reproduction. |
