Low visibility watermark using time decay fluorescence

• US 6,996,252 B2
• Filed: 04/05/2004
• Issued: 02/07/2006
• Est. Priority Date: 04/19/2000
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Reed, Alastair M., Berkley, Lou H. Jr.
• Primary Examiner(s): Johns, Andrew W.
• Application Number:
  US10/818,938
• Publication Number:
  US 20050013463A1
• Time in Patent Office: 673 Days
• Field of Search: 382/100, 382/191, 382/232, 380/51, 380/54, 380/55, 713/176, 358/3.28, 235/468, 235/491, 250/271
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0042 Fragile watermarking, e.g. so as to detect tampering
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• 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 1/32208 involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition H04N1/32219, H04N1/32224 take precedence
• CPC Class Codes: H04N 1/32229 with selective or adaptive application of the additional information, e.g. in selected regions of the image H04N1/32213 takes precedence
• CPC Class Codes: H04N 1/32251 in multilevel data, e.g. greyscale or continuous tone data
• CPC Class Codes: H04N 1/32293 Repeating the additional information in a regular pattern
• CPC Class Codes: H04N 1/32309 in colour image data
• CPC Class Codes: H04N 2201/327 which are undetectable to the naked eye, e.g. embedded codes

Abstract

A physical object is embedded with a first digital watermark component and a second digital watermark component. The first component is printed using a first ultraviolet (UV) ink. The first UV ink includes a first fluorescence decay time. The second component is printed using a second UV ink. The second ink includes a second fluorescence decay time, which is longer than the first decay time. The embedded media is illuminated with a UV pulse. The first component is detected after the first emission decay time, but before the second emission decay time.

Claims

1. A copy detection method comprising:

receiving optical scan data associated with a printed object, wherein the printed object comprises a first-machine readable component printed thereon with first ink comprising a first emission decay time, and a second component printed thereon with second ink comprising a second emission decay time; and

machine-reading the first component when emissions of the second ink decay to a first predetermined level.

2. The method of claim 1, wherein the second component comprises a machine-readable component.

3. The method of claim 2, wherein machine-reading the first component comprises machine-reading prior to emission of the first ink decay to second predetermined level.

4. The method of claim 1, wherein emissions from the second ink deter machine-reading the first component when above the first predetermined level.

5. The method of claim 1, wherein the first ink and second ink comprise ultraviolet ink.

6. The method of claim 1, wherein the object is deemed a copy or original based on a result of said machine-reading.

7. The method of claim 1, wherein the first-machine readable component comprises a digital watermark component.

8. The method of claim 7, wherein the second component comprises a machine-readable component.

9. The method of claim 8, wherein the second component comprises a digital watermark component.

10. A computer readable medium having computer executable instructions stored therein, the instructions to perform the method of claim 1.

11. A method comprising:

providing a first component in a first color channel, wherein the first color channel is to be printed with a first ink comprising a first emission rate; and

providing a second component in a second color channel, wherein the second component is provided so as to reduce human perceptible artifacts that are attributable to the first component.

12. The method of claim 11, wherein the second component is to be printed with a second ink having a second emission rate, and wherein the second emission rate is at least one of:

i) longer than the first emission rate, and ii) shorter than the first emission rate.

13. A computer readable medium having computer executable instructions stored therein, the instructions to perform the method of claim 11.

14. A copy detection method comprising:

obtaining optical scan data of a physical object, wherein the physical object includes a first digital watermark component embedded in a first channel with a first ink having a first decay time and a second digital watermark component embedded in a second channel, wherein the second digital watermark component is embedded so as to reduce human perceptible artifacts that are attributable to the first digital watermark component; and

analyzing the optical scan data at a predetermined position to obtain at least a portion of the first digital watermark component.

15. The method of claim 14, wherein the portion comprises a message.

16. The method of claim 14, wherein the predetermined position comprises a relative time location.

17. The method of claim 14, wherein second digital watermark component is provided on the object with a second ink having a second decay time, and wherein the predetermined position comprises an emission point in which emissions associated with the second component cease to reduce artifacts so as to allow machine-detection of the first component.

18. A computer readable medium having computer executable instructions stored therein, the instructions to perform the method of claim 17.

19. The method of claim 14, wherein the first ink and the second ink comprise ultraviolet ink.

20. A computer readable medium having computer executable instructions stored therein, the instructions to perform the method of claim 14.

21. A method comprising:

receiving scan data associated with an object, wherein the object comprises a first machine-readable component provided thereon with first ink comprising a first emission decay time, and a second component provided thereon with second ink comprising a second emission decay time; and

machine-reading the first component from the data when emissions of the second ink fall to a first predetermined level.

22. The method of claim 21, wherein the second component comprises a machine-readable component.

23. The method of claim 22, wherein machine-reading the first component comprises machine-reading prior to emission of the first ink decay to second predetermined level.

24. The method of claim 21, wherein emissions from the second ink deter machine-reading the first component when above the first predetermined level.

25. The method of claim 21, wherein the first ink and second ink comprise ultraviolet ink.

26. The method of claim 21, wherein the object is deemed a copy or original based on a result of said machine-reading.

27. The method of claim 21, wherein the first-machine readable component comprises a steganographic component.