Embedded optical signatures in documents

摘要

The invention relates to a method for providing a redundant embedded optical signature on a document (120; 170), wherein the optical signature is in the form of an embedded optical pattern that is generated from and represents a mathematical value embodied as printed geometric relationships of relative distances and angles of various data stars on the document (120; 170), the method comprising the steps of: identifying background space areas (122) on the document (120; 170); defining a plurality of blocks (132, 134, 136, 138) of star fields for the space areas (122), the blocks of star fields having different shapes so as to fit within the available space areas; defining a plurality of galaxies (126; 160; 172) of multiple blocks of star fields, wherein each galaxy comprises a guide cluster (142; 150; 162; 174) having a plurality of guide stars (140; 152) that identify the proper orientation of the galaxy (126; 160; 172) on the document (120; 170) and the remaining blocks of star fields orbit the guide cluster (142; 150; 162; 174) and contain data stars; and wherein only one of the galaxies (126; 160; 172) need be decoded for all of the embedded optical data to be recovered from the document (120; 170). The invention also relates to a respective document.