Hiding information out-of-phase in color channels

• US 6,891,959 B2
• Filed: 04/02/2002
• Issued: 05/10/2005
• Est. Priority Date: 04/19/2000
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Reed, Alastair M., Brundage, Trent J.
• Primary Examiner(s): Patel, Kanjibhai
• Application Number:
  US10/115,444
• Publication Number:
  US 20020168085A1
• Time in Patent Office: 1,134 Days
• Field of Search: 382/100, 382/162, 382/166, 382/232, 382/183, 358/3.28, 283/72, 380/50, 380/234, 380/252, 380/54, 381/73.1, 435/6, 704/270, 705/50, 709/217, 713/176
• 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 20/341 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 1/0042 Fragile watermarking, e.g. so as to detect tampering
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• 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 17/16 for devices exhibiting advertisements, announcements, pictures or the like
• 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: 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 1/32149 : 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 1/32203 : 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 1/32293 : Repeating the additional information in a regular pattern
• CPC Class Codes: H04N 1/32309 : in colour image data
• 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 21/23892 : involving embedding information at multiplex stream level, e.g. embedding a watermark at packet level
• 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 2201/3233 : 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 2201/3284 : for error correction

Abstract

The present invention relates to steganographically hiding images and information. In a preferred embodiment, an image is hidden within a media signal. The media preferably includes a cyan (C) color plane, a magenta (M) color plane, a yellow (Y) color plane and a black (K) color plane. In an alternative embodiment, the media includes a spot color. The image is converted into a black color channel image and is then applied to the media'"'"'s K channel. The black channel image is inverted and the inverted image is applied to the media'"'"'s CMY (or spot) color planes.

Claims

1. A method of steganographically hiding a first image in a second image, the second image comprising at least a cyan (C) color channel, a magenta (M) color channel, a yellow (Y) color channel and a black (K) color channel, said method comprising:

providing a first set of signal modifications corresponding to the first image;

modifying the K color channel with the first set of signal modifications;

providing a second set of signal modification corresponding to the first image, the second set of signal modifications being inverted with respect to the first set of signal modifications; and

modifying the C, M and Y color channels with the second set of signal modifications.

2. The method of claim 1, further comprising providing a print of the second image once the first image has been hidden therein, wherein the CMY color channel modifications are inverted with respect to the K channel modifications so as to reduce the first image'"'"'s visibility in the print by canceling perceived luminance change in local areas throughout the print.

3. The method of claim 1, wherein the first image comprises at least one of a photograph, bar code, text, an orientation reference for alt least one of the first and second image, and a digital watermark.

4. The method of claim 3, wherein the first image comprises a barcode, which is redundantly embedded throughout the second image.

5. A method of embedding a digital watermark component in a signal having a plurality of channels, said method comprising:

embedding the digital watermark component in a first of the plurality of channels; and

embedding the digital watermark component in a second of the plurality of channels to be out-of-phase with respect to the digital watermark component in the first channel.

6. The method according to claim 5, wherein the plurality of channels comprises color channels and at least one black channel.

7. The method according to claim 6, wherein the color channels comprise cyan, magenta and yellow.

8. The method according to claim 7, further comprising the steps of embedding the digital watermark component in at least a third channel and a fourth channel.

9. The method according to claim 7, wherein the first channel, third channel and fourth channel respectively comprise the cyan, magenta and yellow, and the second channel comprises black.

10. The method according to claim 5, wherein embedding the digital watermark component in a second of the plurality of channels to be out-of-phase with respect to the digital watermark component in the first channel cancels a perceived luminance change in local areas throughout the signal.

11. The method according to claim 9, wherein for at least one signal area each black channel digital watermark component is inverted with respect to a corresponding digital watermark component of a same level in the cyan, magenta and yellow channel.

12. The method according to claim 9, wherein luminance attributable to at least one black channel digital watermark component is cancelled by a luminance change attributable to a corresponding digital watermark component in the cyan, magenta and yellow channels.

13. The method of claim 12, wherein an embedding level of the digital watermark component varies between each of the cyan, magenta and yellow channels.

14. A method of hiding a first image in a second image comprising:

converting the first image to a black channel image;

selecting a location in the second image to hide the black channel image;

modifying the black channel in the selected location to accommodate the black channel image;

providing in terms of at least cyan, magenta and yellow channels a color channel image that is inverted with respect to the black channel image;

modifying the cyan, magenta and yellow channels in the selected location to accommodate the color channel image.

15. The method of claim 14, wherein an effect of inverting the color channel image with respect to the black color image is to counter-balance luminance changes in local areas throughout the selected area.

16. A method of steganographically embedding a bar code in an image, the image including at least a black channel and at least a color channel, said method comprising:

converting the barcode into a set of grayscale values;

in at least one region of the image, modifying the black channel in the region to accommodate the set of grayscale values;

inverting the grayscale values in the set; and

modifying the color channel in the region to accommodate the inverted grayscale values in a manner so that the modified black channel region is inverted with respect to the modified color channel.

17. The method of claim 16, wherein the color channel comprises a spot color.

18. The method of claim 16, wherein the color channel comprises at least a cyan channel, a magenta channel and a yellow channel.

19. The method of claim 18, wherein said modifying the color channel in the region modifies each of the cyan, magenta and yellow channels to accommodate the inverted grayscale values.

20. The method of claim 16, wherein modifying the black channel region to be inverted with respect to the modified color channel offsets, a luminance change in the region that is attributable to modifications of the color channel.

21. A method of embedding a digital watermark component in a signal having a plurality of channels, said method comprising:

embedding a first digital watermark component in a first of the plurality of channels; and

embedding a second digital watermark component in a second of the plurality of channels,

wherein the first component and the second component cooperate to reduce perceptibility of the digital watermark as embedded in the signal.

22. The method of claim 21, wherein the second component cooperates with the fist component by offsetting localized changes in luminance due to the first component.

23. A method of hiding a first image in a second image comprising:

converting the first image to a black channel image;

selecting a location in the second image to hide the black channel image;

modifying the black channel in the selected location to accommodate the black channel image;

providing in terms of at least one color, a color image that is inverted with respect to the black channel image; and

modifying a color channel in the selected location to accommodate the color image.

24. The method of claim 23, wherein the first image comprises machine-readable indicia.

25. The method of claim 23, wherein modifications in the black channel that correspond to the black channel image reduce at least some visible artifacts that are attributable to modifications in the color channel that correspond to the color image.

26. The method of claim 23, wherein the color channel comprises a red channel.

27. The method of claim 26, further comprising modifying a yellow channel and a blue channel in the selected location to accommodate the color image.

28. A method of providing digital watermarking comprising:

providing a first color on a first surface, wherein the first color includes first modifications corresponding to first digital watermarking; and

providing a second color on the first surface, wherein the second color is different than the first color, and wherein the second color includes second modifications corresponding to second digital watermarking, and wherein the first modifications and the second modifications cooperate to reduce perceptibility of the first and second digital watermarking on the first surface.

29. The method of claim 28, wherein the first color comprises a spot color.

30. The method of claim 29, wherein the second color comprises a black color.

31. A printed article resulting from the method of claim 28.

32. A printed article resulting from the method of claim 29.

33. A printed article resulting from the method of claim 30.

34. A method of providing digital watermarking comprising:

providing a first color on a first surface; and

providing a second color that is different than the first color on the first surface, wherein the second color includes modifications corresponding to digital watermarking, and wherein the modifications are at least partially obscured from human perception by at least some portions of the first color.

35. The method of claim 34, wherein the first color comprises a spot color and the second color comprises a black color.

36. The method of claim 34, wherein the portions of the first color comprise modifications corresponding to digital watermarking, and wherein the first color modifications and the second color modifications offset one another in at least some respects so as to reduce visual artifacts that would otherwise be attributable to the digital watermarking.

37. A printed article resulting from the method of claim 34.

38. A printed article resulting from the method of claim 35.

39. A printed article resulting from the method of claim 36.