Image marking adapted to the image

• US 7,062,070 B2
• Filed: 10/21/2004
• Issued: 06/13/2006
• Est. Priority Date: 07/31/1992
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Nitzberg, Mark, Powell, Robert D.
• Primary Examiner(s): Johns, Andrew W.
• Application Number:
  US10/972,286
• Publication Number:
  US 20050117776A1
• Time in Patent Office: 600 Days
• Field of Search: 382/100, 382/232, 380/210, 380/287, 380/54, 713/176
• 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: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• 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: G07D 7/0047 using checkcodes, e.g. coded numbers derived from serial number and denomination
• CPC Class Codes: G07D 7/0056 involving markings of altered colours
• CPC Class Codes: G07D 7/12 Visible light, infrared or ultraviolet radiation
• CPC Class Codes: G07D 7/2008 using pre-processing, e.g. de-blurring, averaging, normalisation or rotation
• CPC Class Codes: G07D 7/2033 Matching unique patterns, i.e. patterns that are unique to each individual paper
• 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 7/12 Card verification
• 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 1/32245 Random or pseudorandom selection of pixels
• 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 1/3232 Robust embedding or watermarking
• CPC Class Codes: H04N 2201/3233 of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/3235 : Checking or certification of the authentication information, e.g. by comparison with data stored independently
• CPC Class Codes: H04N 2201/327 : which are undetectable to the naked eye, e.g. embedded codes

Abstract

A digital image is processed to hide information, by generally inconspicuous adjustments of pixel values. Desirably, the processing is adapted to the particular image being encoded, so as to better conceal the encoding. The method may include determining a relative ability of a pixel to be adjusted inconspicuously, by reference to values of at least two neighboring pixels.

Claims

1. In a method of encoding an image to convey secret information, the method including receiving image data and information to be encoded, and changing the image data to effect encoding, an improvement comprising adapting the encoding to contents of a particular image, wherein the secret information is distributed differently among image components of different first and second images.

2. The method of claim 1 that includes printing the encoded image on a substrate.

3. The method of claim 2 that includes scanning the printed substrate, and discerning the secret information from the scan data.

4. The method of claim 3 that includes performing an algorithmic geometrical registration process on the scan data before said discerning.

5. The method of claim 4 wherein said registration process proceeds with reference to visible features in the image.

6. The method of claim 1 in which the secret information comprises a multi-bit identifier.

7. The method of claim 1 in which the image components comprise pixels.

8. The method of claim 1 in which the encoding includes changing values of image components, and the changes to at least some of said components depend on initial values thereof.

9. The method of claim 1 wherein said encoding results in subtle localized changes to the luminance, but not the chrominance, of said image.

10. The method of claim 1 wherein a difference image comprising the difference between said image before and after encoding includes at least one region showing no change.

11. The method of claim 1 wherein a difference image comprising the difference between said image before and after encoding evidences a pattern, rather than appearing uniform across its extent.

12. The method of claim 1 wherein a difference image comprising the difference between said image before and after encoding shows evident correlation with the image prior to encoding.

13. In a method of encoding an image to convey secret information, the method including receiving image data and information to be encoded, and changing the image data to effect encoding, an improvement comprising adapting the encoding to the particular image, wherein the strength of the encoding varies in accordance with particular features of the image.

14. The method of claim 13 in which, when the image is represented as an array of pixels, the variation in strength comprises variations in pixel values across said array.

15. The method of claim 13 wherein certain neighborhoods of contiguous pixels are deliberately left unchanged to avoid visibly impairing the image.

16. In a method of processing image data to hide information therein, the information comprising more than a single bit, the method including adjusting values of pixels represented by said image data to encode a representation of the information in the image data, an improvement comprising determining a relative ability of a pixel to be adjusted inconspicuously, by a method that takes into account values of at least two neighboring pixels.

17. The method of claim 16 that includes only adjusting values of pixels that are determined to have a relatively high ability to be adjusted inconspicuously.

18. The method of claim 17 that includes only adjusting values of pixels that are found to have values greater than all neighboring pixels.

19. The method of claim 16 that includes determining a relative ability of said pixel to be adjusted inconspicuously by a method that takes into account values of at least two adjoining pixels.

20. The method of claim 19 that includes only adjusting values of pixels that are determined to have a relatively high ability to be adjusted inconspicuously.

21. The method of claim 16 in which said adjusting comprises changing a value of a first pixel by a positive amount, and changing a value of a second pixel by a different positive amount.

22. The method of claim 21 in which said adjusting comprises changing a value of a third pixel by a negative amount, and changing the value of a fourth pixel by a different negative amount.

23. The method of claim 16 that includes adjusting values of less than all of the pixels represented by said image data.

24. In a method of processing image data to hide information therein, the information comprising more than a single bit, the method including adjusting values of pixels represented by said image data to encode a representation of the information in the image data, an improvement comprising determining a relative ability of a pixel to be adjusted inconspicuously by reference to a difference between first and second parameters, where said parameters are functions of values of neighboring pixels.

25. The method of claim 24 wherein said first parameter is an average of pixels within a first neighborhood around said pixel, and said second parameter is an average of pixels within a second, larger, neighborhood around said pixel.

26. In a method of processing image data to hide information therein, the information comprising more than a single bit, the method including changing values of pixels represented by said image data to encode a representation of the information in the image data, an improvement comprising receiving a parameter corresponding to a pixel, said parameter being a function of values of first and second pixels adjoining said pixel, and using said received parameter in adapting the encoding to the image.

27. The method of claim 26 that additionally includes computing said parameter, using at least values of said first and second pixels adjoining said pixel.

28. The method of claim 27 in which said computation also uses the value of said pixel.

29. In a method of processing image data to hide information therein, the information comprising more than a single bit, the method including changing values of pixels represented by said image data to encode a representation of the information in the image data, an improvement comprising receiving plural parameters, one for each of several different regions of the image, each parameter relating to the relative ability of said region to be altered without conspicuously changing the image, each parameter being a function of plural pixels values, the method further including using said received parameters in adapting the encoding to the image.

30. The method of claim 29, wherein each of said regions comprises a single pixel.

31. The method of claim 29 wherein said image data comprises a film clip.

32. A method of encoding an image to convey binary data in the image by making changes to the image that are inconspicuous, the method comprising:

distributing the binary data among pixels in the image according to a random pattern; and

encoding the binary data in the image by making changes to the image as a function of image values, the encoding being dependent on characteristics of the image that make the changes inconspicuous.

33. The method of claim 32 wherein the changes are made inconspicuous, at least in part, by making a change at a point in the random pattern as well as to an area around the point to lessen visibility of the change at the point.

34. The method of claim 32 that includes printing the encoded image, wherein the binary data is automatically detectable from an image scan of the printed encoded image.

35. A method of encoding an image to convey binary data in the image by making changes to the image that are inconspicuous, the method comprising:

distributing the binary data among pixels in the image according to a pattern; and

encoding the binary data in the image by making changes to the image as a function of image values such that strength of encoding varies with features in the image, the encoding being dependent on features of the image that make the changes inconspicuous.