Authenticating of documents containing security features having different spectral responses

摘要

Entire document is scanned with multi-spectral beam so that security features (2-6) on the document react with different spectral responses which are detected by sensors. Complete document is scanned with multi-spectral light to detect position of security features relative to coordinate system of the document. Position of markings is detected due to brightness, contrast, color and pattern differences relative to the rest of the document background. Then the security feature is checked only in the image areas corresponding to the position detected. Security features are machine readable text (2) with a line which does not reflect in selected scan of near infrared light, a two-dimensional bar code (3), diffractive element (4) which reflects diffraction pattern in coherent light of specific wavelength and picture (5) containing steganographically hidden information.