Protecting images with image markings

• US 7,068,811 B2
• Filed: 03/27/2002
• Issued: 06/27/2006
• Est. Priority Date: 07/31/1992
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Powell, Robert D., Nitzberg, Mark
• Primary Examiner(s): Johns, Andrew W.
• Application Number:
  US10/113,398
• Publication Number:
  US 20030026450A1
• Time in Patent Office: 1,553 Days
• Field of Search: 382/100, 382/112, 382/232, 340/5.86, 356/71, 902/1, 902/4, 902/6, 283/17, 283/72, 283/73, 283/113, 283/901, 380/210, 380/287, 380/54
• 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 method and system for embedding signatures within visual images in both digital representation and print or film. A signature is inseparably embedded within the visible image, the signature persisting through image transforms that include resizing as well as conversion to print or film among the pixels of an original image. The pixel values of the signature points and surrounding pixels are adjusted by an amount detectable by a digital scanner. The adjusted signature points form a digital signature which is stored for future identification of subject images derived from the image. In one embodiment, a signature is embedded within an image by locating relative extrema in the continuous space of pixel values and selecting the signature points from among the extrema. Preferably, the signature is redundantly embedded in the image such that any of the redundant representations can be used to identify the signature. Identification of a subject image includes ensuring that the subject image is normalized with respect to the original image or the signed image. Preferably, the normalized subject image is compared with the stored digital signature.

Claims

1. A method for imparting a watermark pattern onto a digitized image comprising the steps of:

providing said digitized image comprised of a plurality of pixels, wherein each of said pixels includes brightness data that represents a brightness of at least one color; and

adjusting said brightness data associated with at least one of said pixels by a predetermined adjustment factor, said adjustment factor adjusting said brightness data by no more than +/−

10%;

wherein the watermark pattern has a relationship with a random number.

2. A method as recited in claim 1, wherein each pixel is associated with a brightness data value that represents a brightness of a monochrome color.

3. A method as recited in claim 1, wherein each pixel is associated with a plurality of brightness data values.

4. A method as recited in claim 3, wherein said plurality of brightness data values represents brightness of a color vector.

5. A method as recited in claim 1, wherein said watermark has an invisibility classification level of undetectably invisible.

6. A method as recited in claim 1, wherein said watermark pattern further includes a proportional mapping to provide a desired modulation strength.

7. A method as recited in claim 6, wherein said modulation strength is 10%.

8. A method as recited in claim 1 wherein each of said pixels has a row and a column location in an array representing said digitized image.

9. A method as recited in claim 1, wherein said random number is generated by a computer.

10. A method as recited in claim 1, wherein said watermark pattern is formed from a plurality of watermarking parameters.

11. A method as recited in claim 10, wherein said watermarking parameters provide the watermark with at least one property of a robust invisible watermark.

12. A method for generating a watermarked image wherein a watermark is imparted onto a digitized image having a plurality of original elements having original brightnesses, said method comprising the steps of:

providing a digitized watermarking signal comprising a plurality of watermarking elements, each having a watermark brightness adjusting factor and having correspondence with said original elements; and

producing a watermarked image by adjusting said original brightness of each of said original elements corresponding to one of said watermark elements, the brightness adjusting factor being computed from the digitized image such that the adjusting is imperceptible.

13. A method as recited in claim 12, wherein said producing step adjusts said original brightness by no more than +/−

10%.

14. A method as recited in claim 12, in which said watermark signal corresponds to locations in an area smaller than the digitized image.

15. The method as recited in claim 14, wherein the watermarking signal is produced by finding locations in the original image that withstand changes in the watermarked image.

16. A method as recited in claim 12, wherein each of said original elements include a plurality of brightness values corresponding to a color vector.

17. A method for generating a watermarked image wherein a watermark is imparted onto a digitized image having a plurality of original elements having original brightnesses, said method comprising the steps of:

providing a digitized watermarking signal comprising a plurality of watermarking elements, each having a watermark brightness adjusting factor and having correspondence with said original elements;

producing a watermarked image by adjusting said original brightness of each of said original elements corresponding to one of said watermark elements; and

truncating said original plane without destroying said watermarking signal, wherein said watermark is invisible, said watermarking signal corresponds to locations in an area smaller than the digitized image.

18. A method for generating a watermarked image wherein a watermark is imparted onto a digitized image having a plurality of original elements having original brightnesses, said method comprising the steps of:

providing a digitized watermarking signal comprising a plurality of watermarking elements, each having a watermark brightness adjusting factor and having correspondence with said original elements; and

producing a watermarked image by adjusting said original brightness of each of said original elements corresponding to one of said watermark elements, wherein said watermark is invisible, said original image forms an original plane, said watermarking signal corresponds to locations in an area smaller than the digitized image and is produced by employing a Difference of Averages technique.

19. A method for imparting a watermark onto a digitized image comprising the steps of:

providing said digitized image comprised of a plurality of pixels, wherein each of said pixels includes brightness data that represents a brightness of at least one color; and

adjusting said brightness data associated with at least one of said pixels by not more than +/−

10% using an adjustment factor,

wherein said watermark has a relationship with a random number,

said watermark further includes a proportional mapping to provide a desired modulation strength.

20. A method for imparting a watermark onto a digitized image, said method comprising:

providing a digitized image, said image being represented by an image array having a plurality of pixels, said pixels having at least one color component, said watermark being formed using a distinct watermarking signal represented by an array having a plurality of distinct watermarking elements, each of said distinct watermarking elements having an array position and having positional correspondence with said image pixels, and multiplying said brightness data associated with said at least one color component by an adjustment factor, wherein said adjustment factor relates to a corresponding distinct watermarking element, and said watermark has an invisibility classification.

21. A computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing a watermark to be imparted into an image, the computer readable program code means in said computer program product comprising computer readable program code means for causing a computer to effect the steps of claim 20.

22. An apparatus to impart a watermark onto a digitized image, said apparatus comprising mechanisms for implementing the method of claim 20.

23. A method of embedding a watermark into a digital color image, wherein said image has I rows and J columns, and has a pixel in row i and column j having at least one brightness, Y(i, j), the method comprising:

generating a watermark signal based on a random number; and

altering the digital color image to embed the watermark in the color image, including adding to or subtracting from the brightness Y(i, j) corresponding elements of the watermark signal, wherein 1 is less than or equal to i is less than or equal to I and 1 is less than or equal to j is less than or equal to J are the row and column indices of a pixel location in the image.

24. A method as recited in claim 23, wherein the altering includes making a change in brightness that is proportional to an original brightness of the pixel.

25. An apparatus for imparting a watermark onto a digitized image comprising mechanisms for implementing the method of claim 24.

26. A computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing a watermark to be imparted into an image, the computer readable program code means in said computer program product comprising computer readable program code means for causing a computer to effect the steps of claim 23.

27. An apparatus for imparting a watermark onto a digitized image comprising mechanisms for implementing the method of claim 23.

28. A method for imparting a watermark onto a digitized image comprising the steps of:

providing said digitized image comprised of a plurality of pixels, wherein each of said pixels inchides brightness data that represents a brightness of at least one color, with said image having I rows and J columns, and pixel in row i and column j having a brightness Y(i, j); and

for a plurality i and at least one j adding to or subtracting from the brightness Y(i, j) a value, wherein 1 is less than or equal to i is less than or equal to I and 1 is less than or equal to j is less than equal to J are the row and column indices of a pixel location in the image, and wherein the value is an element in a watermark signal generated with a random signal.

29. A computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing a watermark to be imparted into an image, the computer readable program code means in said computer program product comprising computer readable program code means for causing a computer to effect the steps of claim 28.

30. An apparatus for imparting a watermark onto a digitized image comprising mechanisms for implementing the method of claim 28.

31. A method for generating a watermarked image, the method comprising:

imparting a watermark onto a digitized image having a plurality of original pixels, each of said pixels having at least one original pixel brightness value;

providing said watermark comprising a plurality of watermarking elements, each element having a watermark brightness adjustment and having a positional correspondence with said original pixels; and

producing a watermarked image by multiplying said original brightness of each of said original pixels by an adjustment factor of a corresponding one of said watermark elements.

32. A computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing generation of a watermarked image, the computer readable program code means in said computer program product comprising computer readable program code means for causing a computer to effect the steps of claim 31.

33. An apparatus for generating a watermarked image comprising mechanisms for implementing the method of claim 31.

34. A method for imparting a watermark pattern onto a digitized image comprising the steps of:

providing said digitized image comprised of a plurality of image pixels with said digitized image having I rows and J columns, and a pixel in row i and column j having at least one component, Y(i, j); and

adding to or subtracting from said brightness data associated with at least one of said pixels a predetermined brightness adjustment in the range of 0 to Y(i, j), wherein said watermark pattern has a relationship with a random number.

35. An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein for causing a watermark to be imparted onto a digitized image, the computer readable program code means in said article of manufacture comprising computer readable program code means for causing a computer to effect the steps of claim 34.

36. A method for detecting a watermark comprising the steps of:

providing an image having a plurality of image pixels, u(i, j), with said image having I rows and J columns, and a pixel in row i and column j having at least one component, marked by a watermark;

said watermark having a plurality of watermarking elements, w(i, j), with said watermark having a brightness adjustment;

aligning said image;

identifying a subset of said image elements; and

for each pixel, u(i, j), of said subset of image pixels, employing a detection scheme in determining a probability of watermark detection based on a property of a random watermark pattern used to modify brightness of the image.

37. A method of hiding a code in a signal representing image data, said method comprising:

selecting positions in the signal for hiding the code based at least in part on predetermined criteria; and

adjusting at least one value corresponding to the signal at or around a selected position to hide the code based at least in part on one or more values corresponding to the signal at or around the selected position, wherein redundant instances of the code are hidden in the signal at or around the selected positions.

38. The method of claim 37 wherein the predetermined criteria comprises a pattern.

39. The method of claim 37 wherein the predetermined criteria comprises a function.

40. The method of claim 39 wherein the function comprises a random function.

41. The method of claim 37 wherein the predetermined criteria comprises a sequence.

42. The method of claim 37 wherein the predetermined criteria is stored in a computing device.

43. The method of claim 37 wherein the image data comprises at least one of luminance values and color values.

44. The method of claim 37 wherein said adjusting adapts adjusting in proportion to at least one value at or around a selected position.

45. The method of claim 44 wherein the proportion comprises a percentage of the at least one value.