Hiding Codes in Input Data

• US 20080298703A1
• Filed: 08/11/2008
• Published: 12/04/2008
• Est. Priority Date: 07/31/1992
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Powell, Robert D., Nitzberg, Mark J.
• Granted Patent: US 7,593,545 B2
• Time in Patent Office: Days
• US Class Current: 382/251
• 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

The present invention relates to hiding codes in input data such as still imagery and motion pictures. One claim recites: embedding an N-bit code with a source signal, N being at least one. The embedding proceeds, for each bit of the N-bit code, according to the following: mapping the bit to a portion of the source signal; changing values of at least two data values associated with the portion in accordance with the bit. The act of changing embeds the N-bit code in a manner that is generally imperceptible to a human observer of the source signal. A related claim recites that the portion includes a data value, and the above method further includes changing the value of the data value in accordance with said bit of the code, an amount of the changing being adjusted based on the value. Of course, other claims and combinations are provided as well.

Claims

1. A method comprising:

selecting data representing a source signal as a point at which a code is embedded;

changing at least one value associated with the source signal at the point, and

wherein an amount of a change introduced by said act of changing varies in dependence on a value associated with the source signal at the point, so that a smaller value is changed less than a larger value, and

wherein change to the source signal is made essentially human imperceptible by varying the change in dependence on the value associated with the source signal, with a smaller value being changed less than a larger value.

2. The method of claim 1 wherein the source signal comprises data representing imagery.

3. The method of claim 1 wherein the portion comprises a location.

4. The method of claim 3 wherein the value comprises a value associated with one or more pixels.

5. The method of claim 1 wherein the act of selecting utilizes a predetermined pattern.

6. The method of claim 1 wherein the source signal comprises digital imagery having a plurality of pixels, which with each pixel having digital image data values associated therewith,

the code comprises N bits, N being at least one,

the act of selecting selects more than N pixels as signature points,

for each of the selected signature points, the act of changing changes a digital data value at the signature point by increasing or decreasing the digital image value at the signature point according to a value of a bit of the signature to be mapped at the signature point, and

the amount of the changing is adjusted based on the digital data values at the signature point.

7. The method of claim 6, further comprising storing the code for future identification.

8. The method of claim 6 wherein each pixel has at least a luminance value and a color value associated therewith, and

the act of changing changes a luminance value at each of the signature points, and

the signature points are spaced apart from each other.

9. The method of claim 1 wherein the selecting comprises randomly selecting data at which the code is embedded.

10. The method of claim 1 wherein the selecting comprises selecting data at which the code is embedded according to a pattern.

11. The method of claim 1 wherein the source signal comprises data representing a motion picture.

12. A method including:

evaluating data hiding characteristics of plural portions of a host signal; and

embedding an N-bit code, where N is greater than 1, in the host signal by avoiding portions of the host signal that have poor data hiding characteristics, which are identified as areas having smaller variations in data associated with luminance or color values than other portions of the host signal;

the code is embedded in data that it is relatively less perceptible to a human observer of the host signal.

13. The method of claim 12 wherein said act of evaluating comprising determining amounts of variations in luminance or color values of data representing the host signal to determine data hiding characteristics of the host signal, the data hiding characteristics corresponding to the amounts of variations.

14. A method comprising:

identifying portions of a host signal having a predetermined data hiding attribute including determining amounts of signal or data value variation to identify portions having the predetermined data hiding attribute; and

changing the host signal in at least certain identified portions to effect embedding of a N-bit code, N being at least one, therein, and

the N-bit code is embedded in the host signal where it is relatively less perceptible to a human observer of the host signal.

15. The method of claim 14 wherein the signal or data variation includes a variation in luminance or color values of the host signal.

16. The method of claim 14 wherein the host signal comprises data representing imagery.

17. The method of claim 16 wherein the imagery comprises data representing a motion picture.

18. The method of claim 14 wherein the predetermined data hiding attribute corresponds to a relationship of portions with larger variations relative to other portions.

19. A method comprising:

embedding an N-bit code with a source signal, N being at least one, said embedding proceeding, for each bit of the N-bit code, according to the following;

mapping said bit to at least one data value representing the source signal;

changing a value of the data value in accordance with said bit of the code, an amount of the changing being adjusted based on the value; and

also changing values of at least two additional data values in accordance with said bit;

wherein the acts of changing embed the N-bit code in a manner that is generally imperceptible to a human observer of the source signal.

20. The method of claim 19 wherein changes to the source signal are effected in groups of data values, yielding a more robust embedding of the code in the source signal that better withstands corruption of the source signal with the embedded code.

21. The method of claim 19 wherein the source signal comprises imagery including pixels, the method includes changing the imagery at plural portions thereof, the change at each portion increase or decrease a value associated with a pixel at each said portions, and the changes at pixels adjoining each said portions increase or decrease the value associated with each pixel adjoining said signature pixels to correspond to the change of the code pixel adjacent thereto.

22. The method of claim 19 wherein the mapping comprises randomly choosing data values in the source signal.

23. The method of claim 19 wherein the mapping comprises choosing data values in the source signal according to a pattern.

24. A method comprising:

embedding an N-bit code with a source signal, N being at least one, said embedding proceeding, for each bit of the N-bit code, according to the following;

mapping said bit to a portion of the source signal;

changing values of at least two data values associated with the portion in accordance with said bit;

wherein the act of changing embeds the N-bit code in a manner that is generally imperceptible to a human observer of the source signal.

25. The method of claim 24 wherein the portion comprises a data value, and said method further comprises changing the value of the data value in accordance with said bit of the code, an amount of the changing being adjusted based on the value.

26. A method comprising:

identifying plural points representing imagery;

increasing the value of each of a first group of said identified points, and also increasing the values of a first group of associated points; and

decreasing the value of each of a second group of said identified points, and also decreasing the values of a second group of points.

27. The method of claim 26 including pseudorandomly identifying the plural points representing the imagery.

28. The method of claim 26 including identifying the plural points representing the imagery according to a pattern.