Methods and sytems using multiple watermarks

• US 20020061121A1
• Filed: 12/07/2001
• Published: 05/23/2002
• Est. Priority Date: 05/08/1995
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B., Gustafson, Ammon E.
• Granted Patent: US 6,744,906 B2
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0071 using multiple or alternating watermarks
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06T 2201/0202 whereby the quality of watermarked images is measured; Measuring quality or performance of watermarking methods; Balancing between quality and robustness
• CPC Class Codes: G06T 2207/30144 Printing quality
• CPC Class Codes: G06T 7/0002 Inspection of images, e.g. flaw detection
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G07C 9/253 visually
• CPC Class Codes: G07F 7/08 by coded identity card or credit card or other personal identification means without personal verification means G07F7/02
• CPC Class Codes: G07F 7/086 by passive credit-cards adapted therefor, e.g. constructive particularities to avoid counterfeiting, e.g. by inclusion of a physical or chemical security-layer for security documents G07D7/00; for the reading of record-carriers in general G06K7/00; for the design of coded credit-cards G06K19/10
• CPC Class Codes: G07F 7/12 Card verification
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: H04N 1/00002 Diagnosis, testing or measuring; Detecting, analysing or monitoring not otherwise provided for error detection, error correction or monitoring in digital computers or digital computer components G06F11/00
• CPC Class Codes: H04N 1/00005 relating to image data
• CPC Class Codes: H04N 1/00037 Detecting, i.e. determining the occurrence of a predetermined state H04N1/00031 takes precedence
• CPC Class Codes: H04N 1/00092 relating to the original or to the reproducing medium, e.g. imperfections or dirt detecting properties of a sheet H04N1/00681
• CPC Class Codes: H04N 1/32144 embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• CPC Class Codes: H04N 1/32149 Methods relating to embedding, encoding, decoding, detection or retrieval operations
• CPC Class Codes: H04N 1/32304 Embedding different sets of additional information
• CPC Class Codes: H04N 1/32309 : in colour image data
• CPC Class Codes: H04N 1/32315 : Selecting a particular method from amongst a plurality of methods
• CPC Class Codes: H04N 1/32331 : Fragile embedding or watermarking
• CPC Class Codes: H04N 1/32352 : Controlling detectability or arrangements to facilitate detection or retrieval of the embedded information, e.g. using markers for decoding, detection or retrieval operations H04N1/32149 and subgroups take precedence

Abstract

Two or more digital watermarks, with different characteristics, are embedded in a document. The characteristics are chosen so that the watermarks will be affected in different manners if the document is subsequently copied or reproduced. The detection process or mechanism reads two or more of the watermarks and compares their characteristics. While wear and handling may change the characteristics of the digital watermarks in a document, the relationship between the characteristics of the multiple digital watermarks in a document will nevertheless give an indication as to whether a document is an original or a copy of an original. Document wear can be independently assessed and used as an aid in interpreting the detected watermark characteristics.

Claims

1. A method of determining whether a document is likely an original document, the document comprising a first steganographic watermark and a second steganographic watermark, said method comprising:

reading a first characteristic related to the first steganographic watermark;

reading a second characteristic related to the second steganographic watermark;

reading a third characteristic related to the document'"'"'s physical condition; and

with reference to the first, second and third characteristics, assessing whether the document is likely an original document.

2. The method according to claim 1, wherein the physical condition comprises at least one of wear, handling and soiling.

3. The method according to claim 1, wherein the first characteristic and the second characteristic each comprise a power level.

4. The method according to claim 1, wherein the first characteristic and the second characteristic each comprise a grain level.

5. The method according to claim 1, wherein the first characteristic comprises a first geometric assignment of pixels and the second characteristic comprises a second geometric assignment of pixels.

6. The method according to claim 1, wherein the first characteristic comprises a color transformation characteristic and the second characteristic comprises at least a first bias characteristic.

7. A method for determining whether a printed object is likely an original printed object, the printed object comprising at least a first digital watermark and a second digital watermark, said method comprising:

detecting a first characteristic related to the first digital watermark;

detecting a second characteristic related to the second digital watermark; and

comparing the first characteristic and the second characteristic to determine whether the printed object is likely an original printed object.

8. The method according to claim 7, wherein the first characteristic and the second characteristic each comprise a power level.

9. The method according to claim 8, wherein a comparison of the first power level and the second power level comprises a power ratio.

10. The method according to claim 7, further comprising the step of detecting a third characteristic related to the document'"'"'s physical condition.

11. The method according to claim 10, wherein the document'"'"'s physical condition comprises at least one of wear, handling and soiling.

13. The document of claim 12, wherein the first corruption process includes wear, and the second corruption process includes scanning and printing.

12. A document including a substrate with printing thereon, the printing comprising at least a first steganographic watermark and a second steganographic watermark, the first steganographic watermark comprising a first characteristic and the second steganographic watermark comprising a second characteristic, wherein the first and second characteristics are affected in a different manner when the document is subjected to a first corruption process and a second corruption process.