Low visibility watermark using time decay fluorescence

• US 6,718,046 B2
• Filed: 08/31/2001
• Issued: 04/06/2004
• Est. Priority Date: 05/08/1995
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Berkley, Lou H. Jr., Reed, Alastair M.
• Primary Examiner(s): Patel, Jayanti K.
• Application Number:
  US09/945,243
• Publication Number:
  US 20020090112A1
• Time in Patent Office: 949 Days
• Field of Search: 382/100, 382/112, 382/135, 382/140, 382/162, 382/312, 347/107, 358/3.28, 380/201, 380/55, 713/176
• US Class Current: 382/100
• CPC Class Codes: B41M 3/14 Security printing securities B42D25/29
• CPC Class Codes: B41M 3/144 using fluorescent, luminescent or iridescent effects
• CPC Class Codes: B42D 25/00 Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof printing processes to produce identification or security features B41M3/14
• CPC Class Codes: B42D 25/333 Watermarks
• CPC Class Codes: B42D 25/382 absorbing or reflecting infrared light
• CPC Class Codes: B42D 25/387 absorbing or reflecting ultraviolet light
• CPC Class Codes: G06F 16/955 using information identifiers, e.g. uniform resource locators [URL]
• CPC Class Codes: G06K 19/06037 multi-dimensional coding
• CPC Class Codes: G06K 19/06046 Constructional details
• CPC Class Codes: G06K 19/14 the marking being sensed by radiation
• CPC Class Codes: G06K 19/18 Constructional details
• CPC Class Codes: G06K 2019/06253 for a specific application
• CPC Class Codes: G06K 7/1417 2D bar codes
• CPC Class Codes: G06K 7/1447 extracting optical codes from image or text carrying said optical code
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G06Q 20/40145 Biometric identity checks
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• 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: G06V 30/40 Document-oriented image-based pattern recognition
• CPC Class Codes: G07C 9/253 : visually
• CPC Class Codes: G07D 7/0034 : using watermarks
• CPC Class Codes: G07D 7/004 : using digital security elements, e.g. information coded on a magnetic thread or strip
• CPC Class Codes: G07F 17/16 : for devices exhibiting advertisements, announcements, pictures or the like
• 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 7/1008 : Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• 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: G11B 20/00884 : involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm
• CPC Class Codes: G11B 20/00891 : embedded in audio data
• 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 1/00079 : remotely
• CPC Class Codes: H04N 1/32122 : in a separate device, e.g. in a memory or on a display separate from image data
• CPC Class Codes: H04N 1/32149 : Methods relating to embedding, encoding, decoding, detection or retrieval operations
• CPC Class Codes: H04N 1/32154 : Transform domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/3216 : using Fourier transforms
• CPC Class Codes: H04N 1/32203 : Spatial or amplitude domain methods H04N1/32309 takes precedence
• 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 1/32288 : Multiple embedding, e.g. cocktail embedding, or redundant embedding, e.g. repeating the additional information at a plurality of locations in the image
• 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 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
• CPC Class Codes: H04N 19/467 : characterised by the embedded information being invisible, e.g. watermarking
• CPC Class Codes: H04N 21/23892 : involving embedding information at multiplex stream level, e.g. embedding a watermark at packet level
• CPC Class Codes: H04N 21/8358 : involving watermark protecting executable software by watermarking G06F21/16; image watermarking in general G06T1/0021; watermarks inserted in still images for transmission purposes H04N1/32144; inserting watermarks during video coding H04N19/467
• CPC Class Codes: H04N 2201/3205 : of identification information, e.g. name or ID code H04N2201/3209 takes precedence
• CPC Class Codes: H04N 2201/3207 : of an address
• CPC Class Codes: H04N 2201/3225 : of data relating to an image, a page or a document
• CPC Class Codes: H04N 2201/3226 : of identification information or the like, e.g. ID code, index, title, part of an image, reduced-size image
• CPC Class Codes: H04N 2201/3233 : of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/327 : which are undetectable to the naked eye, e.g. embedded codes
• CPC Class Codes: H04N 2201/3271 : Printing or stamping
• CPC Class Codes: H04N 2201/3274 : Storage or retrieval of prestored additional information
• CPC Class Codes: H04N 2201/3284 : for error correction

Abstract

Media is embedded with an out-of-phase digital watermark. A first component of the digital watermark is printed using a first ultraviolet (UV) ink. The first UV ink includes a first fluorescence decay time. The second digital watermark component is inverted with respect to the first component and 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 watermark is detected after the first emission decay time, but before the second emission decay time. The watermark is fragile under steady-state UV illumination since the inverted watermark component cancels the non-inverted component.

Claims

1. A printing method comprising the steps of:

printing on a surface a first digital watermark component with a first ink having a first emission decay time; and

printing on the surface a second digital watermark component with a second ink having a second emission decay time.

2. The method according to claim 1, wherein the first digital watermark component is out-of-phase with respect to the second digital watermark component.

3. The method according to claim 1 wherein the second digital watermark component is inverted with respect to the first digital watermark component, and wherein the first component and second component each include at least one attribute that is spatially registered on the surface.

4. The method according to claim 3 wherein the second emission decay time is longer than the first emission decay time.

5. The method according to claim 4, wherein the first ink and the second ink emit in the ultraviolet spectrum.

6. The method according to claim 4, wherein the first ink and the second ink emit in the infrared spectrum.

7. The method according to claim 4, wherein the first ink and the second ink emit visible light when excited with ultraviolet light.

8. The method according to claim 7, wherein the ultraviolet light comprises black ultraviolet light.

9. The method according to claim 4, further comprising the step of shielding the surface from visible light.

10. The method according to claim 4, further comprising the step of filtering visible light.

11. The method according to claim 4, wherein the first ink is printed with a first plate and the second ink is printed with a second plate.

12. The method according to claim 4, wherein the first ink prints the first digital watermark component in a cyan, magenta and yellow channel and the second ink prints the second digital watermark component in a black channel.

13. The method according to claim 4, wherein the first emission decay time and the second emission decay time each comprise at least one of emission exhaustion and emissions falling below a threshold level.

14. The method of claim 1, wherein the first digital watermark component is printed so as to cancel at least some of a change in luminance that is attributable to the second digital watermark component.

15. A method to detect a digital watermark embedded in media, the digital watermark comprising a first component printed with a first ink and a second component printed with a second ink, the second ink comprising an emission decay time that is longer than an emission decay time of the first ink, said method comprising the steps of:

exciting the first ink and the second ink; and

detecting the digital watermark after emissions from the first ink fall to a first predetermined level and before emissions from the second ink fall to a second predetermined level.

16. The method according to claim 15, wherein the first component is inverted with respect to the second component, and wherein at least one part of the first component and one part of the second component are spatially aligned in the media.

17. The method according to claim 15, wherein the first ink and second ink each emit in the ultraviolet spectrum.

18. The method according to claim 15, wherein the first ink and second ink emit each in the infrared spectrum.

19. The method according to claim 15, wherein the first ink and the second ink each emit visible light when excited with ultraviolet light.

20. The method according to claim 15, wherein said detecting step comprises gating a camera to capture emissions from the second ink after emissions from the first ink fall to a first predetermined level and before emissions from the second ink fall to a second predetermined level.

21. The method according to claim 15, wherein said exciting step comprises pulsing an illumination source.

22. The method according to claim 21, further comprising a second step of exiting the first ink and the second ink after emissions from the first ink fall to the first predetermined level and before emissions from the second ink fall to the second predetermined level.

23. The method according to claim 22, wherein said second exciting step comprises pulsing the illumination source.

24. A document comprising a digital watermark embedded thereon, said digital watermark comprising:

a first component applied with a first ink comprising a first emission decay time; and

a second component applied with a second ink comprising a second emission decay time.

25. The document according to claim 24, wherein the first component is inverted with respect to the second component, and wherein the first component and the second component are spatially registered with one another on the document.

26. The method according to claim 25, wherein the second emission decay time is longer than the first emission decay time.

27. The method according to claim 26, wherein the document comprises at least one of a certificate, paper, label, tag, product packaging, thin films, identification card, bank note, treasury bond, cardboard, metal foil, fabric, property title, plastic, metal insurance receipt, contract and trading card.

28. The method according to claim 26, wherein the first emission decay time and the second emission decay time comprise at least one of emission exhaustion and emissions falling below a threshold level.

29. The document according to claim 24, wherein the first component is applied on the document so as to counteract a luminance change tat is attributable to the second component at least while the document is under steady-state illumination.

30. A digital watermarking method comprising the steps of:

embedding a first digital watermark signal in at least a first color channel;

embedding a second digital watermark signal in at least a second color channel;

printing on a surface the embedded first color channel with a first ink comprising a first emission decay time; and

printing on the surface the embedded second color channel with a second ink comprising a second emission decay time,

wherein the second digital watermark signal is embedded in the second color channel so as to cancel at least some of a luminance change that is attributable to the first digital watermark signal at least while the printed surface is under steady-state illumination.

31. The method according to claim 30, wherein the first color channel comprises a cyan channel, a magenta channel and a yellow channel and the first ink comprises a cyan, magenta and yellow ink, and wherein the second color channel comprises a black channel and the second ink comprises a black ink.

32. The method according to claim 31, wherein the second decay time is longer than the first decay time.

33. The method according to claim 32, wherein the first decay time is longer than the second decay time.

34. The method of claim 30, wherein the second digital watermark signal is inverted with respect of the first digital watermark signal.

35. A digital watermarking method comprising the steps of:

embedding a first digital watermark component in a first color channel, wherein the first color channel is to be printed with a first ink having a first decay time

embedding a second digital watermark component in a second color channel, wherein the second digital watermark component is embedded so as to be spatially registered with the first digital watermark component when printed to reduce a change in luminance that is attributable to the first digital watermark component.

36. The digital watermarking method of claim 35, further comprising:

printing the embedded first color channel with the first ink; and

printing the embedded second color channel with a second ink having a second decay time, the first decay time being different than the second decay time.

37. A data hiding method comprising the steps of:

providing a first message component in a first color channel, wherein the first color channel is to be printed with a first ink comprising a first emission decay time;

providing a second message component in a second color channel, wherein the second message component is provided so as to be spatially registered with the first message component when printed to reduce visibility artifacts that are attributable to the first message component.

38. The data hiding method of claim 37, wherein the second message component is to be printed with a second ink having a second emission decay time, and wherein the second emission decay time is at least one of longer than the first emission decay time and shorter than the first emission decay time.