Method and apparatus for discerning image distortion by reference to encoded marker signals

• US 6,567,533 B1
• Filed: 04/27/2000
• Issued: 05/20/2003
• 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:
  US09/561,407
• Time in Patent Office: 1,118 Days
• Field of Search: 382/100, 382/112, 382/232, 382/250, 382/251, 382/252, 382/244, 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, 235/382, 235/494, 395/135, 358/124, 358/142, 358/448, 358/450, 358/454, 358/3.28, 348/475, 356/71, 340/5.53, 340/5.6, 340/5.65, 340/5.8, 340/5.81, 340/5.83, 340/5.86, 902/1, 902/4, 902/6, 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 copy right protecting software against unauthorised usage in a vending or licensing environment, e.g. protection the software providers copyright G06F21/10; data processing systems or methods, specially adapted for payment schemes, architectures or protocols G06Q20/00; secrecy systems or subscription systems H04N7/16
• 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 permit scaling or rotation of an image to be discerned—even if the original image is not available—certain marker signals are steganographically encoded in the image. In one particular implementation, encoding is effected by adding an overlay signal to the image. The overlay signal—when represented in the spatial frequency domain—includes a pattern of spots. If the image is scaled or rotated, this pattern changes in known ways. By examining the change in this pattern, the distortion (i.e., scale/rotation) of the image can be inferred. This technology finds particular application in conjunction with watermarking systems, permitting recovery of watermark data from images that have been scaled or rotated subsequent to watermarking.

Claims

1. A method of image processing that includes encoding the image with additional data that, when represented in the spatial frequency domain, includes a pattern of spot-like orientation markers, said pattern permitting subsequent distortion of the processed image to be characterized, said distortion being scaling or rotation, said encoding being essentially imperceptible to human viewers of the image.

2. The method of claim 1 in which said encoding comprises adding a set of overlay data to image data.

3. The method of claim 1 in which the additional data also encodes plural-bit message data in addition to said orientation markers.

4. The method of claim 1 in which said pattern has at least one axis of symmetry in the spatial frequency domain.

5. The method of claim 1 in which said pattern has two axes of symmetry in the spatial frequency domain.

6. The method of claim 1 in which said pattern includes at least one spot in each of four spatial frequency quadrants of the spatial frequency domain.

7. The method of claim 1 which further includes:

processing a suspect image to discern said orientation markers therein; and

determining scaling or rotation of said image by reference to the pattern of said spots.

8. A method of processing an input image to yield an encoded image, the encoded image being essentially human-indistinguishable from the input image, the method comprising adding an additional signal to said input image, wherein a frame of difference data obtained by subtracting the input image from the encoded image yields a pattern that, when transformed into the spatial frequency domain, includes plural spot features.

9. The method of claim 8 in which said pattern, when transformed into the spatial frequency domain, has at least one axis of symmetry.

10. The method of claim 8 which further includes:

processing a suspect image to discern said spot features therein; and

determining scaling or rotation of said image by reference to a discerned pattern of said spot features.

11. A computer having a memory, the memory having both an image processing program and an image stored therein;

the image having earlier been encoded with additional data that is essentially imperceptible to human viewers of the image and that, when represented in the spatial frequency domain, includes a pattern of spot-like orientation markers;

the image processing program being adapted to discern from said additional data a distortion of said image subsequent to the time of its encoding, said distortion being scaling or rotation.

12. An image processing method that includes encoding an image to secretly convey plural bits of auxiliary data that is essentially imperceptible to human viewers, characterized in that the auxiliary data can be recovered from an encoded image without reference to an unencoded image, the method comprising:

during encoding;

modifying data related to the image so as to yield modified image data that exhibits a characteristic pattern in a transform domain; and

during decoding;

finding a pattern in the transform domain that corresponds to said characteristic pattern, and discerning a transformation of said found pattern from said characteristic pattern.

13. The method of claim 12 in which said modifications also convey the auxiliary data.

14. The method of claim 12 in which said modifications do not encode the auxiliary data, but rather serve just to add information by which distortion of the encoded image can be discerned.

15. The method of claim 12 in which said transform domain is the spatial frequency domain.

16. The method of claim 12 in which the pattern comprises a pattern of energy peaks in the transform domain.

17. The method of claim 12 in which the energy peaks in the encoded image have known positions and spacings.

18. The method of claim 12 in which the decoding makes use of the Fourier-Mellin transform.

19. The method of claim 12 in which the decoding makes use of a pattern matching process.

20. The method of claim 12 that further includes, from said transformation, determining rotation and scaling of the encoded image.

21. An image processing method that includes encoding an image to secretly convey plural bits of auxiliary data that is essentially imperceptible to human viewers, characterized in that the auxiliary data can be recovered from an encoded image without reference to an unencoded image, the method including modifying data related to the image so as to yield modified image data that exhibits a characteristic pattern in a transform domain, said characteristic pattern being useful in decoding to discern scaling or rotation of the encoded image.

22. The method of claim 21 in which said modifications also convey the auxiliary data.

23. The method of claim 21 in which said modifications do not convey the auxiliary data, but rather serve just to add information by which distortion of the encoded image can later be determined.

24. The method of claim 21 in which said transform domain is the spatial frequency domain.

25. The method of claim 21 in which the pattern comprises a pattern of energy peaks in the transform domain.

26. The method of claim 25 in which the energy peaks in the encoded image have known positions and spacings.