Method and system for watermark detection

• US 7,133,536 B2
• Filed: 02/13/2004
• Issued: 11/07/2006
• Est. Priority Date: 08/30/2000
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Prakash, Ravi, Moon, Rodney Gene
• Primary Examiner(s): Wu, Jingge
• Assistant Examiner(s): Lu, Tom Y.
• Application Number:
  US10/778,994
• Publication Number:
  US 20060039580A1
• Time in Patent Office: 998 Days
• Field of Search: 382/100
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: G07D 7/12 Visible light, infrared or ultraviolet radiation
• CPC Class Codes: G07D 7/1205 Testing spectral properties
• CPC Class Codes: G07D 7/202 using pattern matching

Abstract

A system and method of detecting and authenticating a watermark on a document such as a check which is supposed to include a watermark having known characteristics to verify the authenticity of the document. A digitized image of the document is stored and processed through transformation which generates a frequency distribution. That frequency distribution is processed to determine one or more harmonic compared to a stored value associated with the document to determine that a watermark exists and it is the correct watermark.

Claims

1. A method for detecting a watermark in an image of a document including data, the steps of the method comprising:

measuring the distribution of the data on the document;

determining a characteristic frequency of the distribution of the data on the document, wherein the determining of a characteristic frequency comprises ascertaining whether the distribution of data contains a plurality of relative peaks each located at a frequency interval indicative of a beat pattern, wherein the ascertained beat pattern represents the characteristic frequency of the data on the document; and

comparing the characteristic frequency of the data on the document with a frequency which is associated with the document to determine if the document is authentic, wherein the comparing comprises comparing the beat pattern associated with the data on the document with a predetermined beat pattern associated with the document.

2. A method of detecting a watermark in an image of a document including the steps of claim 1 wherein the step of determining a characteristic frequency includes the step of performing a Fourier analysis on the data.

3. A method of detecting a watermark in an image of a document including the steps of claim 1 wherein the step of determining a characteristic frequency includes the step of sampling the data in a rectangular section of the document which is transverse to the direction in which the document was scanned.

4. A method of detecting a watermark in an image of a document including the steps of claim 1 wherein the method further includes reading indicia from the document and determining the correct characteristics for the watermark and comparing the characteristics of the detected watermark to determine that the correct watermark has been identified for the document.

5. A method of detecting a watermark in an image of a document including the steps of claim 4 wherein the step of determining the correct characteristics includes the step of using a lookup table in which the characteristic frequency is stored in the table by account number.

6. A method of detecting a watermark in an image of a document including the steps of claim 3 wherein any watermark on the document is expected to be present in a direction transverse of the scan and in the rectangle extending in the direction of the watermark.

7. A method of determining the authenticity of a document comprising the steps of:

generating an image of the document;

determining at least one characteristic frequency associated with the image of the document, wherein the determining of at least one characteristic frequency comprises obtain mci a frequency distribution of data from the image of the document and ascertaining whether the distribution of data contains a plurality of relative peaks each located at a frequency interval indicative of a beat pattern, wherein the ascertained beat pattern represents the characteristic frequency of the data on the document; and

determining if the at least one characteristic frequency associated with the image of the document as determined matches at least one characteristic frequency for the document if it were authentic, wherein the determining comprises comparing the beat pattern associated with the data on the document with a predetermined beat pattern associated with the document if it were authentic.

8. A method of determining the authenticity of a document comprising the steps of claim 7 and further includes the steps of determining an account number for the document, using the determined account number to ascertain an appropriate frequency for the document and comparing that frequency with the observed frequency.

9. A method of determining the authenticity of a document including the steps of claim 8 wherein the step of ascertaining the appropriate frequency includes the step of looking up the account in a stored lookup table.

10. A method of determining the authenticity of a document comprising the steps of claim 7 and further including the step of determining whether the frequency is close enough to accept the document as authentic.

11. A system of detecting a watermark in a document and comparing the detected watermark to determine the authenticity of the watermark, the system comprising:

an image camera which generates an image of the document;

an image storage which retains the image of the document;

an analysis unit coupled to the image storage which determines a characteristic frequency of the image, wherein the analysis unit obtains a frequency distribution of data from the generated image of the document and ascertains whether the distribution of data contains a plurality of relative peaks each located at a frequency interval indicative of a beat pattern; and

a comparison unit which compares the characteristic frequency determined by the analysis unit with the correct characteristic for the document,

wherein the comparison unit compares the beat pattern associated with the data on the generated image of the document with a predetermined beat pattern associated with the retained image document; and

a rejection unit which identifies documents for which the characteristic frequency is not appropriate for the correct characteristics of the document, whereby the documents which have been identified by the rejection unit may be examined in another way.

12. A system including the elements of claim 11 and further including a stored table including the correct characteristics for a document.

13. A system including the elements of claim 11 wherein the system further includes an apparatus which determines an account number for the document and the correct characteristics for the document are based on the account number.

14. A system including the elements of claim 11 wherein the system further includes an apparatus which determines whether the characteristics of the document are close enough to the appropriate characteristics of the document to allow acceptance of the document.

15. A system including the elements of claim 14 wherein the system further includes a reject pocket and documents which do not have the appropriate characteristics are put in the reject pocket as a result of processing the document.