Watermark embedder and reader

• US 6,614,914 B1
• Filed: 02/14/2000
• Issued: 09/02/2003
• Est. Priority Date: 05/08/1995
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B., Gustafson, Ammon E.
• Primary Examiner(s): Couso, Jose L.
• Application Number:
  US09/503,881
• Time in Patent Office: 1,296 Days
• Field of Search: 382/100, 382/232, 382/284, 382/248, 382/250, 395/135, 358/448, 358/450, 358/454, 358/124, 358/142, 380/7, 380/23, 380/25, 380/54, 283/6, 283/93, 283/94, 348/475, 348/460-468, 235/494, 713/176, 386/94, 705/1, 705/41, 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: B42D 25/333 Watermarks
• 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 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based 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 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 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• CPC Class Codes: G06T 2201/0064 : for copy protection or copy management, e.g. CGMS, copy only once, one-time copy
• CPC Class Codes: G06T 2201/0065 : Extraction of an embedded watermark; Reliable detection
• 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 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: H04H 20/31 : using in-band signals, e.g. subsonic or cue signal
• CPC Class Codes: H04L 63/06 : for supporting key management in a packet data network cryptographic mechanisms or cryptographic arrangements for key management H04L9/08
• 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 1/32149 : 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 1/32187 : with selective or adaptive application of the additional information, e.g. in selected frequency coefficients
• 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 1/32352 : 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 19/645 : by grouping of coefficients into blocks after the transform
• 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 21/44008 : involving operations for analysing video streams, e.g. detecting features or characteristics in the video stream arrangements characterised by components specially adapted for monitoring, identification or recognition of video in broadcast systems H04H60/59
• CPC Class Codes: H04N 21/4627 : Rights management associated to the content security in data switching network management H04L41/28; security management or policies for network security H04L63/20; access security in wireless networks H04W12/08
• 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 2201/323 : for tracing or tracking, e.g. forensic tracing of unauthorized copies
• 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 2201/3284 : for error correction
• CPC Class Codes: H04N 7/163 : by receiver means only

Abstract

A watermark system includes an embedder, detector, and reader. The watermark embedder encodes a watermark signal in a host signal to create a combined signal. The detector looks for the watermark signal in a potentially corrupted version of the combined signal, and computes its orientation. Finally, a reader extracts a message in the watermark signal from the combined signal using the orientation to approximate the original state of the combined signal. While adapted for images, video and audio, the watermark system applies to other electronic and physical media. For example, it can be applied to mark graphical models, blank paper, film and other substrates, texturing objects for ID purposes, etc.

Claims

1. A method of detecting a watermark in a multidimensional signal, the method comprising:

estimating an initial orientation of a watermark signal in the multidimensional signal without reference to an original, un-watermarked version of the multidimensional signal; and

refining the initial orientation to compute a refined orientation, including computing at least one orientation parameter that;

increases correlation between the watermark signal or watermark signal attribute and the multidimensional signal, or

improves recovery of known watermark message bits from the watermark signal, when the watermark or multidimensional signal are adjusted with the refined orientation.

2. The method of claim 1 including:

estimating initial watermark candidates of the watermark signal in the multidimensional signal;

refining the initial orientation candidates to compute refined orientation candidates, including for each candidate;

computing at least one orientation parameter that increases correlation between the watermark signal or watermark signal attributes and the multidimensional signal when the watermark or multidimensional signal are adjusted with the refined orientation candidate.

3. The method of claim 2 wherein:

the initial and refined candidates are computed for portions of the multidimensional signal;

and the refined candidates are further refined by comparing similarity of orientation candidates from different portions, and evaluating merits of the candidates based on similarity.

4. The method of claim 3 wherein the portions are from a single image frame.

5. The method of claim 3 wherein the portions are from different image frames.

6. The method of claim 1 including:

evaluating a candidate by extracting watermark values from the multidimensional signal and determining the extent to which the watermark values match expected values.

7. A method of detecting a watermark in a target signal, the method comprising:

computing orientation parameter candidates of a watermark signal in different portions of the target signal;

comparing similarity of orientation parameter candidates from the different portions of the target signal;

based at least in part on comparing the similarity of the orientation parameter candidates, determining an orientation of the watermark in the target signal.

8. The method of claim 7 wherein the portions of the target signal are from a single image frame.

9. The method of claim 7 wherein portions of the target signal are from different frames.

10. A method of detecting a watermark in a target signal:

estimating orientation of the watermark in the target signal;

using the orientation to extract a measure of the watermark in the target; and

using the measure to assess merits of the estimated orientation.

11. The method of claim 10 wherein the measure includes an extent to which values of image samples in the target signal are consistent with the watermark.

12. The method of claim 10 wherein the measure includes an extent to which values of watermark message bits read from the target signal are consistent with expected bits.

13. A watermark detector comprising:

means for computing orientation of a watermark signal in a target signal without reference to an original, un-watermarked version of the target signal;

means for adjusting at least portions of the target signal based on the orientation; and

means for reading a message encoded in the watermark signal from the adjusted target signal portions.

14. The detector of claim 13 wherein means for computing the orientation includes:

means for estimating orientation parameters; and

means for refining the orientation parameters.

15. The detector of claim 14 including:

means for estimating orientation parameters from different portions of the target signal;

means for grouping orientation parameters from different portions of the target signal.

16. The detector of claim 15 wherein the different portions are different spatial portions of the signal.

17. The detector of claim 15 wherein the different portions are different temporal portions of the signal.

18. The detector of claim 14 including:

means for estimating rotation and scale parameters;

means for refining the rotation and scale estimates;

means for estimating translation parameters; and

means for refining the translation parameters.