Signal processing to hide plural-bit information in image, video, and audio data

• US 6,542,620 B1
• Filed: 07/27/2000
• Issued: 04/01/2003
• 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): Johns, Andrew W.
• Application Number:
  US09/626,984
• Time in Patent Office: 978 Days
• Field of Search: 382/100, 382/232, 380/210, 380/252, 380/287, 380/54, 713/176, 381/73.1, 704/200.1, 704/273, 370/527, 370/529, 348/461, 348/463
• US Class Current: 382/100
• 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 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 1/0057 Compression invariant watermarking
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: G06T 2201/0081 whereby both original and watermarked images are required at decoder, e.g. destination-based, non-blind, non-oblivious
• CPC Class Codes: G07C 9/253 visually
• CPC Class Codes: G07D 7/0032 using holograms
• 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 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 20/00884 : 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: 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 1/00838 : Preventing unauthorised reproduction
• CPC Class Codes: H04N 1/00846 : based on detection of a dedicated indication, e.g. marks or the like
• 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 1/32208 : 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 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 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 2201/3226 : 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 2201/328 : Processing of the additional information
• CPC Class Codes: H04N 5/913 : for scrambling ; for copy protection

Abstract

A variety of techniques for steganographically encoding digital data into, and decoding steganographically data from, audio, video, and image signals (“content signals”) are disclosed. One method encodes a sampled input signal in a manner wherein a single signal sample is processed in accordance with plural bits of binary data. Another technique globally distributes a plural-bit code throughout a content signal, so that the code can be fully discerned from an analysis of even a fraction of the encoded signal, and wherein the encoding takes the form of low level pseudo-random noise. Another technique involves decoding steganographic data from an encoded content signal without reference to an unencoded version of the content signal. A variety of other techniques are also disclosed.

Claims

1. In a method of steganographically processing an input signal to hide a multi-bit message code therein, thereby yielding a steganographically encoded output signal, the input signal representing audio or image data, the input and output signals each comprising a plurality of samples, an improvement comprising processing each one of a plurality of input signal samples in accordance with plural bits of the multi-bit message code to yield said output signal.

2. The method of claim 1 in which each of said plurality of samples is changed in value by said processing.

3. The method of claim 1 in which each of a plurality of samples in the input signal is processed in accordance with at least four bits of said multi-bit message code.

4. The method of claim 1 in which each sample in the input signal is processed in accordance with plural bits of said multi-bit message code.

5. The method of claim 1 in which each sample of the input signal is processed in accordance with each of the bits of said multi-bit message code.

6. An image processing method according to claim 1 in which the input and output signals each represents image data.

7. A video processing method, the video including a plurality of image frames, comprising performing the method of claim 6 on a plurality of said frames.

8. An audio processing method according to claim 1 in which the input and output signals each represents audio data.

9. A computer readable medium having instructions stored thereon for performing the method of claim 1.

10. A signal processing method that includes steganographically encoding an input signal to embed a multi-bit message code therein, the input signal representing image or audio data, the method including processing said input signal in accordance with noise data and said multi-bit message code to produce an output signal having the message code steganographically encoded therein, the method further including encoding the message code throughout the output signal so that the message code can be recovered from first and second non-overlapping excerpts of the output signal, and representing the encoded message code differently as a function of data independent of the input signal in said first and second excerpts to reduce signal degradation and increase message security, said noise data comprising an independent pseudo-random sequence of digital values.

11. An image processing method according to claim 10 in which the input and output signals each represents image data.

12. The method of claim 11 in which the image data is video data.

13. An audio processing method according to claim 10 in which the input and output signals each represents audio data.

14. A computer readable medium having instructions stored thereon for performing the method of claim 10.

15. An image processing method that includes steganographically encoding an input signal representing an image to embed a multi-bit message code therein, the method including processing said input signal in accordance with said multi-bit message code to produce an output signal having the message code steganographically encoded therein, said processing encoding the message code throughout the output signal so that the message code can be recovered from first and second non-overlapping excerpts of the output signal, said encoding comprising generating an overlay signal in a pixel domain, and processing said overlay signal with the input signal to yield the output signal image;

and representing the encoded message code differently in said first and second excerpts to reduce image degradation and increase message security.

16. The method of claim 15 in which the input signal and the overlay signal each is comprised of plural signal samples, and the processing comprises performing binary addition operations between corresponding samples of the input and overlay signals.

17. A computer readable medium having instructions stored thereon for performing the method of claim 15.

18. An audio processing method that includes steganographically encoding an input signal representing audio data to embed a multi-bit message code therein, the method including processing said input signal in accordance with said multi-bit message code to produce an output signal having the message code steganographically encoded therein, said processing encoding the message code throughout the output signal so that the message code can be recovered from first and second non-overlapping excerpts of the output signal, said encoding comprising:

processing the message code to generate an overlay signal in the time domain, said overlay signal representing the message code differently in different temporal portions thereof as a function of a key mapping message symbols to input signal characteristics and as a function of masking attributes of the input signal; and

combining the adapted overlay signal with the input signal.

19. A computer readable medium having instructions stored thereon for performing the method of claim 18.

20. A signal processing method that includes steganographically encoding an input signal to embed a multi-bit message code therein, the input signal representing image or audio data, the method including processing said input signal in accordance with said multi-bit message code to produce an output signal having the message code steganographically encoded therein, the method further including encoding the message code throughout the output signal so that the message code can be recovered from first and second non-overlapping excerpts of the output signal, wherein:

said output signal comprises a plurality of samples, each having a value;

there exists a correspondence between bits of the message code and samples of the output signal; and

each one of a plurality of samples in the output signal corresponds to plural bits of the message code.

21. An image processing method according to claim 20 in which the input signal represents image data, and the processing occurs in a pixel domain.

22. A computer readable medium having instructions stored thereon for performing the method of claim 20.

23. A signal processing method that includes steganographically encoding an input signal to embed a multi-bit message code therein, the input signal representing image or audio data, the method including processing said input signal in accordance with said multi-bit message code to produce an output signal having the message code steganographically encoded therein, an improvement including:

encoding the message code throughout the output signal so that the message code can be recovered from first and second non-overlapping excerpts of the output signal, wherein;

encoding of the message code in the first excerpt is manifested as a first set of difference data additively overlaid with said excerpt;

encoding of the message code in the second excerpt is manifested as a second set of difference data additively overlaid with said excerpt; and

said first and second sets of difference data are uncorrelated due in part to a key used to vary the encoding of the message code in each excerpt.

24. A computer readable medium having instructions stored thereon for performing the method of claim 23.

25. An image processing method that includes steganographically encoding an input signal to embed a multi-bit message code therein, the method including processing said input signal in accordance with said multi-bit message code to produce an output signal having the message code steganographically encoded therein, the input and output signals representing image data, the method further including encoding the message code throughout the output signal so that the message code can be recovered from first and second non-overlapping excerpts of the output signal, wherein said processing includes performing binary addition operations in a pixel domain to add an overly signal to the input signal to yield the output signal.

26. An image processing method that includes steganographically encoding an input image to embed a multi-bit message code therein, the input image comprising picture data, the method including processing said input image in accordance with said multi-bit message code to produce an output image having the message code steganographically encoded therein, the method further including encoding the message code throughout the output image so that the message code can be recovered from first and second non-overlapping excerpts of the output image;

and representing a given bit of the encoded message code differently, both in absolute and percentage terms, in said first and second excerpts to reduce image degradation and increase message security, wherein;

said picture data comprises a plurality of pixels, each having a value, and in which the method further includes;

corrupting the output image following said encoding process, said corrupting changing the values of a plurality of said pixels, said corrupting including printing a visually perceptible image corresponding to said output image on paper, and thereafter scanning said paper with a scanner to provide data for decoding; and

thereafter accurately decoding the message code from said data for decoding notwithstanding said corruption.

27. A computer readable medium having instructions stored thereon for performing the method of claim 26.

28. A signal processing method that includes steganographically encoding an input signal to embed a multi-bit message code therein, the input signal representing audio or image data, the method including processing said input signal in accordance with said multi-bit message code to produce an output signal having the message code steganographically encoded therein, the method further including encoding the message code throughout the output signal so that the message code can be recovered from first and second non-overlapping excerpts of the output signal, wherein bits of said message code collectively represent first and second data fields, one of said fields serving to identify a proprietor of the audio or image data, the other of said fields serving to track particular audio or image data, wherein the output signal includes samples that are embedded with data from both of the first and second fields.

29. A computer readable medium having instructions stored thereon for performing the method of claim 28.

30. In a signal processing method that includes altering an input signal to hide plural bit digital data therein without such alteration being evident to a human observer or listener, the signal representing visual or audio information, an improvement wherein the plural-bit digital data comprises at least a first plural bit subset representing first information, and a second plural bit subset representing second information distinct from the first, wherein the altered input signal includes samples that are each embedded with data from both of the first and second plural bit subsets according to at least one embedding key independent of the input signal.

31. The method of claim 30 in which the plural-bit digital data additionally comprises a third plural-bit subset representing one or more check values relating to the first or second subsets.

32. The method of claim 30 in which the first subset represents a proprietor of the input signal.

33. A computer readable medium having instructions stored thereon for performing the method of claim 30.

34. In a signal processing method that includes altering an input signal to hide plural bit digital data therein without such alteration being evident to a human observer, the signal representing visual information, an improvement wherein the plural-bit digital data comprises at least a first plural bit subset representing first information, and a second plural bit subset representing second information distinct from the first wherein the plural bit digital data additionally comprises calibration data.

35. In a method of detecting plural bit digital data that is steganographically encoded in audio or image data, an improvement wherein the plural bit digital data is detected without reference to an unencoded version of the audio or image data, and detection of certain said bits are used to derive data used to convert characteristics of the audio or video to bit values for other of said bits.

36. A computer readable medium having instructions stored thereon for performing the method of claim 35.

37. A method comprising:

providing original data representing audio or visual information;

providing a plural-bit code;

steganographically encoding the plural-bit code in the original data to yield encoded data, wherein;

the plural-bit code is distributed globally throughout the encoded data, and can be fully discerned from an analysis of even a fraction of the encoded data; and

a set of difference data resulting from subtraction of the original data from the encoded data appears as low level pseudo-random noise, wherein message bits in the plural-bit code are repeated in the encoded data but represented differently as a function of data independent of the input signal.

38. The method of claim 37 wherein the amplitude of said noise varies in accordance with the original data.

39. A computer readable medium having instructions stored thereon for performing the method of claim 37.

40. A method comprising:

providing encoded data representing audio or visual information, the encoded data having a plural-bit code distributed globally therethrough, the encoded data having a low level pseudo-random noise component introduced by the encoding of the plural-bit code; and

discerning the plural-bit code by an analysis of less than all of the encoded data using a key that changes representation of repeated instances of the message symbols over the encoded data.

41. The method of claim 40 in which said discerning proceeds by reference to statistical analysis of the encoded data.

42. A computer readable medium having instructions stored thereon for performing the method of claim 40.