Automated methods for distinguishing copies from original printed objects
First Claim
1. A method, comprising:
- determining, using a computing device, whether a machine-readable auxiliary signal is embedded in an image of a printed object, wherein determining comprises detecting at least one of a divergence or convergence of at least one characteristic of a set of two or more print structures embedded in the printed object such that the machine-readable auxiliary signal becomes one of more or less detectable, wherein the at least one characteristic changes a detection zone of the auxiliary signal in the image based on the at least one characteristic having a gray level value that varies as a function of location in the printed object; and
evaluating the machine-readable auxiliary signal, using the computing device, to determine whether the printed object is an original version of the printed object.
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Abstract
This disclosure describes methods for using embedded auxiliary signals in documents for copy detection and other applications. In on application, the auxiliary signal is formed as an array of elements selected from a set of print structures with properties that change differently in response to copy operations. These changes in properties of the print structures that carry the embedded auxiliary signal are automatically detectable. For example, the changes make the embedded auxiliary signal more or less detectable. The extent to which the auxiliary data is detected forms a detection metric used in combination with one or more other metrics to differentiate copies from originals. Examples of sets of properties of the print structures that change differently in response to copy operations include sets of colors (including different types of inks), sets of screens or dot structures that have varying dot gain, sets of structures with different aliasing effects, etc. Robust and fragile watermarks are used in Image Replacement Documents for a variety of applications. Digital watermarks act as on-board mediators in authentication of a variety of printed documents. Finally, digital watermarks are used to help manage quality of the scanners used in imaging systems.
287 Citations
24 Claims
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1. A method, comprising:
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determining, using a computing device, whether a machine-readable auxiliary signal is embedded in an image of a printed object, wherein determining comprises detecting at least one of a divergence or convergence of at least one characteristic of a set of two or more print structures embedded in the printed object such that the machine-readable auxiliary signal becomes one of more or less detectable, wherein the at least one characteristic changes a detection zone of the auxiliary signal in the image based on the at least one characteristic having a gray level value that varies as a function of location in the printed object; and evaluating the machine-readable auxiliary signal, using the computing device, to determine whether the printed object is an original version of the printed object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A non-transitory computer-readable medium having instructions stored thereon, the instructions comprising:
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instructions to determine whether a machine-readable auxiliary signal is embedded in an image of a printed object, wherein determining comprises detecting at least one of a divergence or convergence of at least one characteristic of a set of two or more print structures embedded in the printed object such that the machine-readable auxiliary signal becomes one of more or less detectable, wherein the at least one characteristic of the print structures changes a detection zone of the auxiliary signal in the image based on the at least one characteristic having a gray level value that varies as a function of location in the printed object; and instructions to evaluate the machine-readable auxiliary signal to determine whether the printed object is an original version. - View Dependent Claims (15)
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16. A method comprising:
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embedding, using a computing device, a machine-readable auxiliary signal in an image at embedding locations using at least one print structure wherein embedding comprises configuring the at least one print structure to change a detection zone of the auxiliary signal in the image, wherein the change causes at least one of a divergence or convergence of at least one characteristic of the at least one print structure such that the machine-readable auxiliary signal becomes one of more or less detectable, and wherein the change is based on the at least one characteristic having a gray level value that varies as a function of location in the image; and creating a metric based at least in part on the machine-readable auxiliary signal embedded in the image, using a computing device, to facilitate detection of the convergence or divergence from a scanned image of a suspect printed object to determine whether the suspect printed object is a copy of a printed object.
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17. A non-transitory computer-readable medium having instructions stored thereon, the instructions comprising:
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instructions to embed a machine-readable auxiliary signal in an image at embedding locations using at least one print structure wherein embedding comprises configuring the at least one print structure to change a detection zone of the auxiliary signal in the image, wherein the change causes at least one of a divergence or convergence of at least one characteristic of the at least one print structure such that the machine-readable auxiliary signal becomes one of more or less detectable, and wherein the change is based on the at least one characteristic having a gray level value that varies as a function of location in the image; and instructions to create a metric, based in part on the machine-readable auxiliary signal embedded in the image, to facilitate detection of the convergence or divergence from a scanned image of a suspect printed object to determine whether the suspect printed object is a copy.
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18. A method, comprising:
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determining, using a computing device, whether a machine-readable auxiliary signal is embedded in an image of a printed object, wherein determining comprises detecting at least one of a divergence or convergence of at least one characteristic of at least one print structure embedded in the printed object such that the machine-readable auxiliary signal becomes one of more or less detectable, wherein the at least one characteristic of the at least one print structure changes a detection zone of the auxiliary signal in the image based on the at least one characteristic having a gray level value that varies as a function of location in the printed object, and wherein the at least one print structure comprises a color; and determining, based on evaluating the machine-readable auxiliary signal, using a computing device, whether the printed object is an original version of the printed object. - View Dependent Claims (19)
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20. A non-transitory computer-readable medium having instructions stored thereon, the instructions comprising:
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instructions to determine whether a machine-readable auxiliary signal is embedded in an image of a printed object, wherein determining comprises detecting at least one of a divergence or convergence of at least one characteristic of the at least one print structure embedded in the printed object such that the machine-readable auxiliary signal becomes one of more or less detectable, wherein the at least one characteristic of the at least one print structure changes a detection zone of the auxiliary signal in the image based on the at least one characteristic having a gray level value that varies as a function of location in the printed object, and wherein the at least one print structure comprises a color; and instructions to determine, based on evaluating the machine-readable auxiliary signal, whether the printed object is an original version of the printed object. - View Dependent Claims (21)
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22. A device comprising:
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a memory configured to store an image of a printed object; and a processor operatively coupled to the memory and configured to; determine whether a machine-readable auxiliary signal is embedded in the image of the printed object, wherein determining comprises detecting at least one of a divergence or convergence of at least one characteristic of a set of two or more print structures embedded in the printed object such that the machine-readable auxiliary signal becomes one of more or less detectable, wherein the at least one characteristic of the print structures changes a detection zone of the auxiliary signal in the image based on the at least one characteristic having a gray level value that varies as a function of location in the printed object; and evaluate the machine-readable auxiliary signal to determine whether the printed object is an original version of the printed object.
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23. A device comprising:
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a memory configured to store an image; and a processor operatively coupled to the memory and configured to; embed a machine-readable auxiliary signal in an image at embedding locations using at least one print structure, and wherein embedding comprises configuring the at least one print structure to change a detection zone of the auxiliary signal in the image, wherein the change causes at least one of a divergence or convergence of at least one characteristic of the at least one print structure such that the machine-readable auxiliary signal becomes one of more or less detectable, and wherein the change is based on the at least one characteristic having a gray level value that varies as a function of location in the image; and create a metric, based at least in part on the machine-readable auxiliary signal embedded in the image, to facilitate detection of the convergence or divergence from a scanned image of a suspect printed object to determine whether the suspect printed object is a copy.
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24. A device comprising:
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a memory configured to store an image of a printed object; and a processor operatively coupled to the memory and configured to; determine whether a machine-readable auxiliary signal is embedded in the image, wherein determining comprises detecting at least one of a divergence or convergence of at least one characteristic of at least one print structure embedded in the printed object such that the machine-readable auxiliary signal becomes one of more or less detectable, wherein the at least one characteristic of the at least one print structure changes a detection zone of the auxiliary signal in the image based on the at least one characteristic having a gray level value that varies as a function of location in the image, and wherein the at least one print structure comprises a color; and determine, based on evaluating the machine-readable auxiliary signal, whether the printed object is an original version of the printed object.
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Specification