Method and system for recognizing security documents

• US 6,674,886 B2
• Filed: 10/28/1999
• Issued: 01/06/2004
• Est. Priority Date: 11/03/1998
• Status: Expired due to Term

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Perry, Burt W., Davis, Bruce L., Shaw, Gilbert B., Rhoads, Geoffrey B., Carr, J. Scott
• Primary Examiner(s): Johns, Andrew W.
• Application Number:
  US09/428,359
• Publication Number:
  US 20030202677A1
• Time in Patent Office: 1,531 Days
• Field of Search: 382/135, 382/137, 382/226, 382/281, 382/100, 340/5.2, 340/5.4, 340/5.8, 340/5.86, 356/71, 713/176
• US Class Current: 382/135
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: G06F 2221/2101 Auditing as a secondary aspect
• CPC Class Codes: G06V 10/40 Extraction of image or video features
• CPC Class Codes: G07D 7/0034 using watermarks
• CPC Class Codes: G07D 7/20 Testing patterns thereon G07D7/004, G07D7/005 take precedence
• CPC Class Codes: H04N 1/00843 based on recognising a copy prohibited original, e.g. a banknote pattern authentication and markers therefor, forgery detection G06V20/95; character recognition G06V30/10; document-oriented image-based pattern recognition G06V30/40; testing paper currency or similar valuable papers for genuineness G07D7/00
• CPC Class Codes: H04N 1/00877 Recording information, e.g. details of the job

Abstract

A document is analyzed to determine whether it is a banknote or the like, by reference to image data corresponding to the document. Two analysis techniques may be used, one based on detection of a visible pattern characteristic of a security document, the other based on detection of a steganographic digital watermark characteristic of a security document. If either characteristic is found, the image is flagged, and appropriate anti-counterfeiting steps may be taken. Detection of the visible pattern can be performed using a series of successively more rigorous tests. If the image fails a test, successive testing steps can be skipped, speeding the process. Hough transform-based pattern recognition techniques are used in some embodiments. Provision of both a visible pattern detector and a watermark detector in a single apparatus enhances detection reliability, while permitting various implementation efficiencies.

Claims

1. A method of processing image data to screen for security document images comprising, in the order stated:

(a) performing a first analysis on the image data;

(b) if the first analysis indicates the image data does not correspond to a security document, skipping steps (c)-(e)

(c) performing a second analysis on the image data;

(d) if the second image analysis indicates the image data does not correspond to a security document, skipping step (e); and

(e) flagging the image data as corresponding to a security document;

wherein at least one of the analyses employs a Hough-based transform to detect a two-dimensional, rotationally invariant feature.

2. The method of claim 1 wherein the image data is acquired by visible light scanning.

3. The method of claim 1 in which one of the analyses employs a Hough-based transform to detect a two-dimensional, rotationally invariant feature at a first rotational state, and another of the analyses employs a Hough-based transform to detect a two-dimensional, rotationally invariant feature at a second, different, rotational state.

4. A method of processing image data to screen for security document images comprising, in the order stated:

(a) performing a first analysis on the image data;

(b) if the first analysis indicates the image data does not correspond to a security document, skipping steps (c)-(e)

(c) performing a second analysis on the image data;

(d) if the second image analysis indicates the image data does not correspond to a security document, skipping step (e); and

(e) flagging the image data as corresponding to a security document;

wherein the first analysis is based on a rotationally invariant feature.

5. The method of claim 4 wherein the image data is acquired by visible light scanning.

6. A method of processing image data to screen for security document images comprising, in the order stated:

(a) performing a first analysis on the image data;

(b) if the first analysis indicates the image data does not correspond to a security document, skipping steps (c)-(e)

(c) performing a second analysis on the image data;

(d) if the second image analysis indicates the image data does not correspond to a security document, skipping step (e); and

(e) flagging the image data as corresponding to a security document;

wherein the first analysis is based on a rotationally symmetric feature.

7. The method of claim 6 wherein the image data is acquired by visible light scanning.

8. A method of processing image data to screen for security document images comprising, in the order stated:

(a) performing a first analysis on the image data;

(b) if the first analysis indicates the image data does not correspond to a security document, skipping steps (c)-(e)

(c) performing a second analysis on the image data;

(d) if the second image analysis indicates the image data does not correspond to a security document, skipping step (e); and

(e) flagging the image data as corresponding to a security document;

wherein one of said analyses steps through plural rotation states of the image data.