Methods and a system for verifying the identity of a printed item

Abstract

A method of verifying an identity of a printed item includes capturing an image of the unverified printed item, wherein the unverified printed item includes artifacts and at least some of the artifacts were not controllably producible in producing the unverified printed item; extracting information associated with the artifacts of the unverified printed item; ranking the information associated with the artifacts of the unverified printed item; retrieving stored ranked information associated with artifacts of an original printed item from a storage device; and in each of a first and second range of magnitudes, comparing the ranked information associated with the artifacts of the unverified printed item with the ranked information associated with the artifacts of the original printed item.

What is claimed is: 
     
         1 . A method of verifying an identity of an unverified printed item, the method comprising:
 on an image capturing device, capturing an image of the unverified printed item,   wherein the unverified printed item includes artifacts and at least some of the artifacts were not controllably producible in producing the unverified printed item;   on a processor:
 extracting information associated with the artifacts of the unverified printed item; 
 ranking the information associated with the artifacts of the unverified printed item; 
 retrieving stored ranked information associated with artifacts of an original printed item from a storage device; 
 in a first range of magnitudes, comparing the ranked information associated with the artifacts of the unverified printed item with the ranked information associated with the artifacts of the original printed item; 
 in a second range of magnitudes, comparing the ranked information associated with the artifacts of the unverified printed item with the ranked information associated with the artifacts of the original printed item, 
 wherein the second range includes artifacts smaller than a smallest artifact in the first range; and 
 when a difference between the ranked information associated with the artifacts of the unverified printed item and the ranked information associated with the artifacts of the original item is greater for the second range than for the first range by more than a threshold amount, identifying the unverified printed item as a copy. 
   
     
     
         2 . The method of  claim 1 , wherein the difference is an average or aggregate difference in or ratio of magnitudes of artifacts or a statistical measure of variation in magnitudes of artifacts. 
     
     
         3 . The method of  claim 1 , further comprising:
 in the first range of magnitudes, assessing a statistical probability that the information associated with the artifacts of the unverified printed item matches the information associated with the artifacts of the original printed item;   in the case the statistical probability exceeds a first threshold, determining that the unverified printed item is the original printed item;   in the case the statistical probability is below a second threshold lower than the first threshold, determining that the unverified printed item is not an original printed item; and   carrying out the comparing steps only in the case the statistical probability is between the first and second thresholds.   
     
     
         4 . The method of  claim 1 , wherein the first range includes a predetermined number of artifacts having largest magnitudes. 
     
     
         5 . The method of  claim 1 , wherein said second range includes a predetermined number of artifacts having magnitudes closest to a smallest recorded magnitude. 
     
     
         6 . The method of  claim 1 , wherein the first and second ranges overlap. 
     
     
         7 . The method of  claim 1 , further comprising calculating an autocorrelation series of the ranked information associated with the artifacts of the unverified printed item for each of the first and second ranges. 
     
     
         8 . The method of  claim 1 ,
 wherein at least some of the artifacts of the unverified printed item are artifacts of a symbol that encodes data and supports error detection,   wherein extracting information representing the artifacts of the unverified printed item includes determining an error state of a symbol having the artifacts of the unverified printed item, and   when the error state indicates that part of the symbol is damaged, discounting artifacts in the damaged part of the symbol.   
     
     
         9 . The method of  claim 1 , wherein each of the comparing steps includes correcting for properties of at least one of an apparatus that created the original artifacts, an apparatus used in examining the original printed item for the information representing the artifacts, and an apparatus used in examining the unverified printed item for the information representing the artifacts. 
     
     
         10 . The method of  claim 9 , wherein:
 the artifacts of the unverified printed item and of the original printed item are of distinct categories;   comparing, in the first range of magnitudes, the ranked information associated with the artifacts of the unverified printed item with the ranked information associated with the artifacts of the original printed item comprises carrying out the comparison in each category and combining the results of the comparisons;   comparing, in the second range of magnitudes, the ranked information associated with the artifacts of the unverified printed item with the ranked information associated with the artifacts of the original printed item comprises carrying out the comparison in each category and combining the results of the comparisons; and   the correcting comprises weighting the combining according to a known tendency of the apparatus that created the original printed item to produce artifacts in different categories with different frequencies or different values of a characteristic.   
     
     
         11 . The method of  claim 1 , further comprising:
 examining an original printed item for artifacts specific to the original printed item;   extracting information associated with the artifacts;   ranking the information according to a characteristic of the artifacts; and   storing data representing the ranked information as said ranked information in a non-transitory computer readable storage device separate from the original printed item.   
     
     
         12 . The method of  claim 11 , wherein:
 the original printed item comprises a mark that comprises an identifier and at least one of the artifacts, wherein the identifier is associated with the original printed item and the at least one artifact does not alter the association; and   the storing comprises storing the information so as to be at least partially locatable using the identifier.   
     
     
         13 . A system for verifying an identity of an unverified printed item, the system comprising:
 an image capturing device that captures an image of the unverified printed item,   wherein the unverified printed item includes artifacts and at least some of the artifacts were not controllably producible in producing the unverified printed item;   a processor that carries out steps comprising:
 extracting information associated with the artifacts of the unverified printed item; 
 ranking the information associated with the artifacts of the unverified printed item; 
 retrieving stored ranked information associated with artifacts of an original printed item from a storage device; 
 in a first range of magnitudes, comparing the ranked information associated with the artifacts of the unverified printed item with the ranked information associated with the artifacts of the original printed item; 
 in a second range of magnitudes, comparing the ranked information associated with the artifacts of the unverified printed item with the ranked information associated with the artifacts of the original printed item, 
 wherein the second range includes artifacts smaller than a smallest artifact in the first range; and 
 when a difference between the ranked information associated with the artifacts of the unverified printed item and the ranked information associated with the artifacts of the original item is greater for the second range than for the first range by more than a threshold amount, identifying the unverified printed item as a copy. 
   
     
     
         14 . The system of  claim 13 , wherein the unverified printed item comprises a plurality of areas and the ranked information associated with the artifacts of the unverified item comprises information associated with the spatial contrast of at least some of the plurality of printed areas. 
     
     
         15 . The method of  claim 14 , wherein the information associated with the spatial contrast of at least some of the printed areas is a moment of inertia of a gray-level co-occurrence matrix. 
     
     
         16 . A system for verifying the authenticity of a printed item, the system comprising:
 an image acquisition device that acquires an image of the printed item; and   one or more processors that carry out actions comprising:
 receiving the image from the image acquisition device; 
 analyzing the image to identify imperfections in the printed item, 
 wherein the imperfections are associated with metrics of a plurality of magnitudes; 
 retrieving a genuine mark signature from a database of genuine mark signatures, 
 wherein the genuine mark signature is based on imperfections of an original printed item, 
 wherein the genuine mark signature contains data of a plurality of magnitudes; 
 in a first range of magnitudes of the identified imperfections and the genuine mark signature, comparing the identified imperfections with the genuine mark signature; 
 in a second range of magnitudes of the identified imperfections and the genuine mark signature, comparing the identified imperfections with the genuine mark signature; 
 wherein the second range of magnitudes includes artifacts smaller than a smallest artifact in the first range; and 
 when a difference between the identified imperfects and the genuine mark signatures is greater for the second range than for the first range by more than a threshold amount, identifying the unverified printed item as a copy. 
   
     
     
         17 . The system of  claim 18 , wherein the printed mark includes coded information regarding a manufactured item. 
     
     
         18 . The system of  claim 18 , wherein the printed mark is a logo. 
     
     
         19 . The system of  claim 18 , wherein
 the coded information includes a unique identifier, and   the one or more processors retrieve the genuine mark signature from the database using the unique identifier.   
     
     
         20 . The system of  claim 1 , wherein the image acquisition device comprises a bar code reader.