Digital watermark decoding method

• US 6,700,990 B1
• Filed: 09/29/1999
• Issued: 03/02/2004
• Est. Priority Date: 11/18/1993
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B.
• Primary Examiner(s): Couso, Jose L.
• Application Number:
  US09/408,026
• Time in Patent Office: 1,616 Days
• Field of Search: 382/100, 382/112, 382/232, 382/284, 395/135, 358/448, 358/454, 358/142, 358/124, 358/450, 358/3.28, 380/4, 380/23, 380/25, 380/54, 380/231-234, 380/287, 283/6, 283/93, 283/94, 283/72, 283/73, 283/113, 283/901, 348/475, 235/494, 390/5.53, 390/5.6, 390/5.65, 390/5.8, 390/5.81, 390/5.83, 390/5.86, 356/71, 902/1, 902/4, 902/6, 902/1.44, 713/176, 386/94, 705/1, 705/44
• US Class Current: 382/100
• 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: 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 20/1235 with control of digital rights management [DRM]
• 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 1/0021 Image watermarking
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06V 30/40 Document-oriented image-based pattern recognition
• CPC Class Codes: G07C 9/253 visually
• CPC Class Codes: G07D 7/0032 using holograms
• 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 17/0014 : for vending, access and use of specific services not covered anywhere else in G07F17/00 meter-controlled dispensing of liquid, gas or electricity G07F15/00
• CPC Class Codes: G07F 17/16 : for devices exhibiting advertisements, announcements, pictures or the like
• CPC Class Codes: G07F 17/26 : for printing, stamping, franking, typing or teleprinting apparatus ticket printing or the like apparatus G07F17/42
• 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 7/1008 : Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: G07F 7/1016 : Devices or methods for securing the PIN and other transaction-data, e.g. by encryption arrangements for secret communication, see H04L9/00
• 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: G11B 20/00094 : involving measures which result in a restriction to authorised record carriers
• CPC Class Codes: G11B 20/00115 : wherein the record carrier stores a unique medium identifier
• CPC Class Codes: G11B 20/00166 : involving measures which result in a restriction to authorised contents recorded on or reproduced from a record carrier, e.g. music or software
• CPC Class Codes: G11B 20/00181 : using a content identifier, e.g. an international standard recording code [ISRC] or a digital object identifier [DOI]
• CPC Class Codes: G11B 20/0021 : involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00231 : wherein the key is obtained from a local external medium, e.g. a card
• CPC Class Codes: G11B 20/0071 : involving a purchase action
• 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: H04B 1/665 : using psychoacoustic properties of the ear, e.g. masking effect
• CPC Class Codes: H04L 2463/103 : applying security measure for protecting copyright
• 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 1/32144 : 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 1/3216 : 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 1/32251 : 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 1/32352 : 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 2005/91321 : the copy protection signal being a copy protection control signal, e.g. a record inhibit signal
• CPC Class Codes: H04N 2005/91335 : the copy protection signal being a watermark
• 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 2201/328 : Processing of the additional information
• CPC Class Codes: H04N 5/913 : for scrambling ; for copy protection
• CPC Class Codes: H04W 24/00 : Supervisory, monitoring or testing arrangements

Abstract

To decode a digital watermark from an image notwithstanding geometrical corruption of the image (e.g., scale, rotation, etc.), a Fourier-Mellin transform is advantageously used. In a particular method, an image is transformed to the spatial frequency domain. Transformed components of the image are then pattern-matched to reference frequencies, and the thus-altered image components are transformed back to the spatial image domain to effect registration of the image prior to watermark decoding.

Claims

1. In an image processing method that includes steganographically decoding an input two-dimensional image to extract a multi-bitcode therein, the image comprising a two-dimensional array of pixels, an improvement comprising:

transforming the image into a different domain; and

pattern matching data related to the transformed image with a reference pattern.

2. The method of claim 1 that further includes identifying, in the registered image, a plurality of regions that encode a first control bit, said regions being distributed through the registered image in a regular array.

3. The method of claim 2 that further includes performing a statistical analysis over at least said plurality of regions to determine whether the first control bit has first or second values.

4. The method of claim 3 that further includes:

if said control bit has the first value, performing a first decoding process on the image to extract the code therefrom; and

if said control bit has the second value, performing a second decoding process on the image to extract the code therefrom, the second decoding process being different than the first.

16. The method of claim 1 in which the different domain is a spatial frequency domain.

21. The method of claim 1 that further includes registering the image for decoding based on results of said pattern matching.

22. The method of claim 1 that further includes determining scale or rotation of the image from an initial state based on results of said pattern matching.

5. In a watermark decoding method that includes receiving content data, and processing same to extract plural-bit auxiliary data therefrom, an improvement comprising:

processing a first part of the auxiliary data to decode information therefrom;

if the decoded information has a first value, continuing said processing in a first manner to extract the auxiliary data; and

if the decoded information has a second value, continuing said processing in a second manner different than the first to extract the auxiliary data.

17. The method of claim 5 in which the content data comprises image data.

18. The method of claim 5 in which the first and second mariners differ in the interpretation of the auxiliary data.

6. In a watermark decoding method that includes receiving image data, and processing same to extract plural-bit auxiliary data therefrom, an improvement wherein the processing includes performing a Fourier-Mellin transform on data related to the image data.

7. The method of claim 6 in which the image data is received in the pixel domain.

8. In a method of steganographically encoding an image to convey plural bit auxiliary data therein, an improvement comprising:

adding to said image a signal comprised of a constellation of marker signals in a transform domain;

wherein said constellation defines a pattern that can be identified and used, in decoding, to discern at least certain transformations of said image.

9. The method of claim 8 wherein said constellation of marker signals permits rotation of the image to be discerned.

10. The method of claim 8 wherein said constellation of marker signals permits scaling of the image to be discerned.

11. The method of claim 8 that further includes steganographically decoding the auxiliary data from the image after said image has been transformed by rotation or scaling.

12. The method of claim 8 in which the transform domain is a spatial frequency domain.

13. The method of claim 9 in which the transform domain is a spatial frequency domain.

14. The method of claim 10 in which the transform domain is a spatial frequency domain.

15. The method of claim 11 in which the transform domain is a spatial frequency domain.

19. In a watermark decoding method that includes receiving content data, and processing same to extract plural-bit auxiliary data steganographically encoded therein, an improvement wherein the auxiliary data comprises a protocol specification portion and a payload portion, and the method includes determining the protocol from the protocol specification portion, and processing the payload portion in accordance with the determined protocol.

20. The method of claim 19 in which the content data comprises image data.

23. A method for embedding a digital watermark robust to geometric transformation, the method comprising:

patterning a watermark signal such that when embedded in an image, the watermark signal forms a registration pattern in a transform domain of the image; and

embedding the watermark signal in an image, wherein the registration pattern enables geometric registration of the watermark signal in the transform domain after the image is rotated and scaled by deriving rotation and scale from a detected registration pattern of the embedded watermark signal in the transform domain.

24. The method of claim 23 wherein the registration pattern comprises a pattern of peaks in the transform domain.

25. The method of claim 23 wherein the transform domain comprises a spatial frequency domain of the image.

26. The method of claim 23 wherein the transform domain comprises a power spectrum of the image.

27. The method of claim 23 wherein the transform domain comprises a Fourier domain of the image.

28. The method of claim 27 wherein the transform domain comprises a square of the Fourier domain.

29. The method of claim 23 wherein patterning includes arranging the watermark signal in an array of regions of contiguous pixels across the image.

30. The method of claim 29 wherein the regions comprise rectangular blocks of pixels.

31. The method of claim 30 wherein the watermark signal comprises a carrier signal modulated with message symbols, and the carrier signal has pseudorandom properties.

32. The method of claim 23 wherein the watermark signal comprises a carrier signal modulated with message symbols to carry an auxiliary message in the image.

33. The method of claim 32 wherein the carrier has pseudorandom properties.