High-speed document verification system

A process useful in document verification, comprising the steps of:

• a. printing at least one valid document with at least a portion thereof having a pattern with a predetermined arrangement of areas having differences in density that are not readily detected by the human eye but are readily detected by an optical scanner, said arrangement representing information regarding validity of a document;
• b. scanning an entirety of a face of an unverified document in a high-speed document scanner to produce an electronic graphic image indicative of the entirety of the face of the unverified document as scanned;
• c. searching said electronic graphic image to find first and second portions of said electronic graphic image;
• and
• d. comparing the first and second portions of said electronic graphic image to said predetermined arrangement of differences to determine if the arrangement is present which would be an indication of the validity of the document, the comparing involving the steps of determining a density in the first portion of the graphic image, determining a density in the second portion of the graphic image, and comparing a ratio of density in the first and second portions to a predetermined value.

A process for automatic verification of documents having a pattern with a predetermined arrangement of areas having differences in print density that are not readily detected by the human eye, but are readily detected by an optical scanner, the differences representing information regarding validity of a document, comprising the steps of:

• a. scanning an entirety of a face of an unverified document with an optical document scanner;
• b. producing an electronic graphic image indicative of the entirety of the face of the unverified document as scanned including print densities of said unverified document;
• c. searching said electronic graphic image to find first and second portions of said electronic graphic image;
• and
• d. comparing a print density in one portion of the graphic image to that in another portion of the graphic image and determining a presence and an absence of the differences based on the comparing which thereby signifies an indication of the validity of the document.