Detecting information hidden out-of-phase in color channels

• US 6,804,377 B2
• Filed: 04/02/2002
• Issued: 10/12/2004
• Est. Priority Date: 04/19/2000
• Status: Expired due to Term

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Brundage, Trent J., Cattone, Jeremy, Reed, Alastair M.
• Primary Examiner(s): Patel, Jayanti K.
• Application Number:
  US10/115,441
• Publication Number:
  US 20020164051A1
• Time in Patent Office: 924 Days
• Field of Search: 382/100, 382/162, 382/163, 382/115, 382/112, 382/135, 382/137, 382/138, 382/140, 382/139, 382/183, 382/232, 382/306, 382/321, 358/3.28, 358/537-539, 380/54, 380/232, 705/51, 705/54, 713/176, 348/661, 348/660
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• 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 1/32293 Repeating the additional information in a regular pattern
• CPC Class Codes: H04N 1/32309 in colour image data
• CPC Class Codes: H04N 2201/327 which are undetectable to the naked eye, e.g. embedded codes

Abstract

The present invention relates to detecting 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. For detection, the embedded media is illuminated with infrared light, which emphasizes the black color plane. An input device captures a digital image of the illuminated media. The image is detected or displayed based on the emphasized black plane.

Claims

1. A method to detect a first image hidden in a second image, the second image comprising a plurality of color channels, wherein the hiding of the first image in the second image comprises at least hiding a first image component in a first of the plurality of color channels, and in the same second image location, hiding the component in a second of the plurality of channels, the second channel component being inverted with respect to the first channel component, said method comprising:

illuminating the embedded second image with infrared light;

capturing a digital image of the illuminated second image; and

analyzing the captured illuminated digital image to detect the first image.

2. The method according to claim 1, wherein the first image comprises at least one of a photograph, graphic, logo, barcode, digital watermark, image, text, message and orientation fiducial.

3. The method according to claim 2, wherein the first color channel comprises black, and the second color channel comprises cyan, magenta and yellow channels, wherein the second channel component is embedded in each of the cyan, magenta and yellow components, the second channel component being inverted in each of the cyan, magenta and yellow channels with respect to the first channel component.

4. The method according to claim 2, wherein the first color channel comprises black and the second color channel comprises cyan, magenta and yellow channels.

5. The method according to claim 4, wherein at least said black color channel conforms to standard web offset press (SWOP) standards.

6. The method according to claim 2, wherein the first color channel comprises black, and the second color channel comprises a spot color.

7. The method of claim 2, wherein the inverted nature of the second channel component with respect to the first channel component cancels localized luminance attributable to the hiding of the first channel component.

8. The method according to claim 1, further comprising shielding the media from visible light.

9. The method according to claim 1, further comprising the step of filtering visible light before said step of capturing a digital image.

10. A method to detect a digital watermark embedded in media, wherein the media includes a plurality of color planes and the digital watermark includes at least a first component and a second component, wherein the second component is embedded in a second color plane at a first media location so as to be inverted in the same media location with respect to the first component embedded in a first color plane so as to cancel luminance attributable to the first component, said method comprising illuminating the media with infrared light or ultraviolet light, and detecting the digital watermark from the illuminated media.

11. The method according to claim 10, wherein the plurality of color planes includes at least a black color plane and the second component is embedded in the black color plane.

12. A method of detecting an orientation fiducial steganographically hidden in a second image to help resolve image distortion, the second image comprising a plurality of color channels, wherein the hiding of the orientation fiducial in the second image comprises hiding the fiducial in a first of the plurality of color channels, and hiding the fiducial in a second of the plurality of channels at the same location as the hidden first channel fiducial, the second channel fiducial being inverted with respect to the first channel fiducial so as to cancel localized luminance attributable to the first channel fiducial, said method comprising the steps of illuminating the second image with infrared light, capturing a digital image of the illuminated second image, and analyzing the captured illuminated digital image to detect the fiducial.

13. The method of claim 12, wherein the fiducial comprises an indication of an original scale and orientation of at least one of the orientation fiducial and second image.

14. The method of claim 13, further comprising comparing the orientation and scale of the detected fiducial to an expected orientation and scale to rescale and reorient the second image.

15. The method of claim 15, wherein said image further comprises a third channel with the fiducial hidden therein at the same spatial location as the hidden first channel fiducial, the image further comprising a fourth channel with the fiducial hidden therein at the same spatial location as the hidden first channel fiducial, wherein the second channel fiducial is inverted with respect to the third channel fiducial and the fourth channel fiducial so as to cancel at least some localized liminance attibutable to the third channel fiducial and fourth channel fiducial.

16. A method to detect a digital watermark embedded in printed media, wherein the printed media includes a plurality of color planes and the digital watermark includes at least a first component and a second component, wherein the second component is embedded so as to visually effect a first spatial area, wherein the embedded second embodiment component reduces at least some visual artifacts at the first spatial area that are attributable to the embedded first component, said method comprising illuminating the media at least one of infrared light and ultraviolet light, and detecting the digital watermark from an image captured from the illuminated media.

17. The method according to claim 16, wherein the plurality of color planes includes at least a black color plane and the second component is embedded in the black color plane.

18. The method of claim 17, wherein the plurality of color planes includes a cyan color plane, a magenta color plane and a yellow color plane, and the first component is embedded in each of the cyan color plane, magenta color plane and yellow color plane.

19. The method of claim 18, wherein the first component is embedded at different strengths in at least one of the cyan color plane, magenta color plane and yellow color plane.

20. The method of claim 16, wherein the visual artifacts comprise a change in luminance that is attributable to the embedded first component.

21. A method to detect a first image hidden in a second image, the second image comprising a plurality of color channels, wherein the hiding of the first image in the second image comprises at least hiding a first image component in a first of the plurality of color channels, and hiding the component in a second of the plurality of channels, the second channel component being hidden so as to be spatially registered with the first image component to reduce at least some visual artifacts that are attributable to the first image component, said method comprising;

illuminating the second image with at least of infrared light and ultraviolet light;

optically capturing an image of the illuminated second image; and

analyzing the captured illuminated image to detect the first image component.

22. The method according to claim 21, wherein the second color channel comprises black, and the first color channel comprises cyan, magenta and yellow channels, wherein the first image component is embedded in each of the cyan, magenta and yellow channels, the second image component being spatially registered with the first image components to reduce at least some visual artifacts that are attributable to the first image component in each of the cyan, magenta and yellow channels.

23. The method of claim 21, wherein the second channel component is hidden so as to be spatially registered with the first image component to cancel at least some localized luminance that is attributable to the hiding of the first image component.

24. The method according to claim 21, wherein the first image comprises at least one of a photograph, graphic, logo, barcode, digital watermark, image, text, message and orientation fiducial.