Digital watermarking in data representing color channels

• US 9,179,033 B2
• Filed: 09/26/2011
• Issued: 11/03/2015
• 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): Bella, Matthew
• Assistant Examiner(s): Rosario, Dennis
• Application Number:
  US13/245,353
• Publication Number:
  US 20120014557A1
• Time in Patent Office: 1,499 Days
• Field of Search: 382/100
• US Class Current: 1/1
• 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 1/0085 Time domain based watermarking, e.g. watermarks spread over several images
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: H04N 1/32144 embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• 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 2201/327 which are undetectable to the naked eye, e.g. embedded codes

Abstract

The present disclosure relates to digital watermarking. One claim recites a method to detect two or more different digital watermarks in media. The method includes: receiving captured imagery of the media, the captured imagery comprising a plurality of image frames; for a first image frame applying a first watermark detector to search for a first digital watermark hidden within the first image frame, in which an electronic processor is programmed as the first watermark detector; and for a second image frame applying a second, different watermark detector to search for a second, different watermark hidden within the second image frame, in which an electronic processor is programmed as the second watermark detector. Other claims and combinations are provided too.

Claims

1. A method comprising:

receiving image data comprising a plurality of pixels, wherein the image data represents a blue channel, a green channel and a red channel for each of the plurality of pixels, wherein the blue channel of a subset of pixels has been adjusted by a first factor to embed steganographic indicia, wherein the green channel and red channel of the subset of pixels have been adjusted by a second factor offsetting a luminance change resulting from adjusting the blue channel by the first factor, and wherein the blue channel, the green channel, and the red channel each comprise distinct pixel components;

minimizing image interference by combining data representing the blue channel in each pixel, data representing the green channel in each pixel and data representing the red channel in each pixel to yield combined red, green, and blue channel data for each pixel;

reducing image saturation by shifting the combined and minimized channel data; and

searching, using a programmed electronic processor or electronic hardware, for the steganographic indicia in the shifted, combined, and reduced channel data.

2. The method of claim 1, wherein the shifted, combined, and reduced channel data represents chrominance characteristics.

3. The method of claim 1, wherein the steganographic indicia comprises a machine-readable code.

4. The method of claim 3, wherein the machine-readable code comprises digital watermarking

5. The method of claim 1, wherein the steganographic indicia comprises an image or graphic.

6. The method of claim 1, wherein reducing image saturation by shifting the combined channel data comprises adding a shift factor.

7. The method of claim 6, wherein the shift factor is in a color value range of 64-192.

8. The method of claim 1, further comprising:

scaling data representing the blue channel using a third factor;

scaling data representing the red channel using a fourth factor, wherein the third factor is different from the fourth factor; and

scaling data representing the green channel using the second factor, wherein minimizing image interference by combining channel data comprises combining the scaled data representing the blue channel, the scaled data representing the red channel, and the scaled data representing the green channel to yield the combined channel data.

9. The method of claim 1, wherein the steganographic indicia comprises an orientation component, and wherein the method further comprises:

detecting a second steganographic indicia in the captured data, wherein the second steganographic indicia is synchronized according to the orientation component.

10. The method of claim 1, wherein minimizing image interference by combining data representing the blue channel, data representing the green channel and data representing the red channel comprises:

shifting the data representing the blue channel by a third factor;

shifting a sum of the data representing the red channel and the data representing the green channel; and

subtracting the shifted sum of the data representing the red channel and the data representing the green channel from the data representing the blue channel to yield combined channel data.

11. The method of claim 1, wherein the first factor is different than the second factor, wherein the second factor is calculated based on the first factor.

12. An apparatus comprising:

a processor configured to;

receive image data comprising a plurality of pixels, wherein the image data represents a blue channel, a green channel and a red channel for each of the plurality of pixels, wherein the blue channel of a subset of pixels has been adjusted by a first factor to embed steganographic indicia, wherein the green channel and red channel of the subset of pixels have been adjusted by a second factor offsetting a luminance change resulting from adjusting the blue channel by the first factor, and wherein the blue channel, the green channel, and the red channel each comprise distinct pixel components;

minimize image interference by combining data representing the blue channel in each pixel, data representing the green channel in each pixel and data representing the red channel in each pixel, to yield combined red, green, and blue channel data for each pixel;

reduce image saturation by shifting the combined channel data; and

search for the steganographic indicia in the shifted, combined, and reduced channel data.

13. The apparatus of claim 12, wherein the shifted, combined, and reduced channel data represents chrominance characteristics.

14. The apparatus of claim 12, wherein the steganographic indicia comprises a machine-readable code.

15. The apparatus of claim 14, wherein the machine-readable code comprises digital watermarking.

16. The apparatus of claim 12, wherein the steganographic indicia comprises an image or graphic.

17. The apparatus of claim 12, wherein to reduce image saturation by shifting the combined channel data the processor is configured to add a shift factor.

18. A non-transitory computer-readable medium having instructions stored thereon, the instructions comprising:

instructions to receive image data comprising a plurality of pixels, wherein the image data represents a blue channel, a green channel and a red channel for each of the plurality of pixels, wherein the blue channel of a subset of pixels has been adjusted by a first factor to embed steganographic indicia, wherein the green channel and red channel of the subset of pixels have been adjusted by a second factor offsetting a luminance change resulting from adjusting the blue channel by the first factor, and wherein the blue channel, the green channel, and the red channel each comprise distinct pixel components;

instructions to minimize image interference by combining data representing the blue channel in each pixel, data representing the green channel in each pixel and data representing the red channel in each pixel, to yield combined red, green, and blue channel data for each pixel;

instructions to reduce image saturation by shifting the combined channel data; and

instructions to search for the steganographic indicia in the shifted, combined, and reduced channel data.

19. The non-transitory computer-readable medium of claim 18, wherein the shifted, combined, and reduced channel data represents chrominance characteristics.

20. The non-transitory computer-readable medium of claim 18, wherein the steganographic indicia comprises a machine-readable code, and wherein the machine-readable code comprises digital watermarking

21. The non-transitory computer-readable medium of claim 18, wherein the instructions to reduce image saturation by shifting the combined channel data comprises instructions to add a shift factor.