Protection of documents against sophisticated photocopying and scanning
Habib Hamam · CRJ · 2023
A novel method, for designing pantographs, is presented. An iterative algorithm is used to design a distribution of bright and dark spots to be embedded in the original document. This distribution should make the word “void”, “invalid”, or “copy” visible on the photocopy or the scanned version of the original document. We used an iterative algorithm to optimize the pantograph. We can start from a random distribution, or from a deterministic distribution based on Dirac pulses properties.