Steganographic Encoding and Decoding

• US 20100322467A1
• Filed: 02/18/2010
• Published: 12/23/2010
• Est. Priority Date: 07/02/2004
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Reed, Alastair M., Sharma, Ravi K., Rodriguez, Tony F.
• Granted Patent: US 8,515,120 B2
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 11/001 Texturing; Colouring; Generation of texture or colour inpainting G06T5/77
• CPC Class Codes: G06T 2201/0083 whereby only watermarked image required at decoder, e.g. source-based, blind, oblivious
• 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 1/32267 combined with processing of the image
• CPC Class Codes: H04N 1/32309 in colour image data
• CPC Class Codes: H04N 1/6005 with luminance or chrominance signals, e.g. LC1C2, HSL or YUV
• CPC Class Codes: H04N 1/6008 with primary colour signals, e.g. RGB or CMY(K)
• CPC Class Codes: H04N 2201/3228 further additional information (metadata) being comprised in the identification information
• 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

Abstract

This patent document relates generally to steganography and digital watermarking. One claim recites, in a watermark encoder, a method of encoding auxiliary information in an image or video comprising: using a programmed electronic processor, computing a change in an attribute of an image or video sample to encode auxiliary information in the image or video; and changing color values of the image or video sample to effect the change in the attribute, in which changes to color values are determined based at least in part on both: i) visibility of the changes, and ii) anticipated watermark detection. Of course, other claims are provided too.

Claims

1. In a watermark encoder, a method of encoding auxiliary information in an image or video comprising:

using a programmed electronic processor, computing a change in an attribute of an image or video sample to encode auxiliary information in the image or video; and

changing color values of the image or video sample to effect the change in the attribute,

in which changes to color values are determined based at least in part on both;

i) visibility of the changes, and

ii) anticipated watermark detection.

2. The method of claim 1 in which the anticipated watermark detection comprises a metric representing distortion attributable to an optical sensor.

3. The method of claim 2 in which the distortion comprises at least one of compression, noise or signal sampling.

4. The method of claim 1 in which the changes to color values are in the blue-yellow direction.

5. The method of claim 1 in which the changes of color values affect each of at least a cyan color channel, a magenta color channel and a red color channel, with the changes being embedding with different embedding significance in at least two of the color channels.

6. The method of claim 1 in which the changes of color values are made to reduce watermark visibility.

7. The method of claim 1 in which the changes in the attribute comprise a change in luminance, and the changes in the color values are made to have an equivalent change in luminance while being weighted differently among a plurality of color channels.

8. The method of claim 1 in which the changes in the attribute comprises a change in chrominance, and the changes in the color components are made to have an equivalent change in chrominance while being weighted differently among a plurality of color channels.

9. A computer readable medium having instructions stored thereon to cause an electronic processor to perform the methods of claim 1.

16. A programmed computing device comprising instructions stored in memory to cause said programmed computing device to perform the method of claim 1.

10. In a watermark detector, a method of decoding auxiliary information encoding in an image or video comprising:

receiving data representing the image or video, wherein the data comprises first data corresponding to a first color channel, second data corresponding to a second color channel and third data corresponding to a third color channel;

weighting the first data, the second data and the third data according to at least the following two factors;

i) a color direction biased toward an anticipated embedding direction; and

ii) anticipated image or video distortion introduced to the first data, second data or third data through scanning or signal processing; and

determining from weighted first data, weighted second data and weighted third data, changes in an image or video attribute, in which the auxiliary information is conveyed through the changes to sample values representing the image or video.

11. The method of claim 10 in which the data is weighted for detection in a blue-yellow direction.

12. The method of claim 10 in which the first data, second data and third data respectively correspond to red, green and blue.

13. The method of claim 10 in which the anticipated image or video distortion is attributable to at least one of compression, signal processing or signal sampling.

14. A computer readable medium comprising instructions stored therein, said instructions cause an electronic processor to perform the method of claim 10.

15. A programmed computing device comprising instructions stored in memory to cause said programmed computing device to perform the method of claim 10.

17. An apparatus comprising:

electronic memory for buffering samples corresponding to an image or video;

an electronic processor programmed for;

computing a change in an attribute of an image or video sample to encode auxiliary information in the image or video; and

changing color values of the image or video sample to effect the change in the attribute, in which changes to color values are determined based at least in part on both;

i) visibility of the changes, and ii) anticipated watermark detection.

18. The apparatus of claim 17 in which the anticipated watermark detection comprises a metric representing distortion attributable to an optical sensor.

19. The apparatus of claim 17 in which the changes in the attribute comprise a change in luminance, and the changes in the color values are made to have an equivalent change in luminance while being weighted differently among a plurality of color channels.

20. The apparatus of claim 17 in which the electronic processor is operating to perform at least one of the functions recited therein.

21. An apparatus comprising:

electronic memory for buffering data representing an image or video, in which the data comprises first data corresponding to a first color channel, second data corresponding to a second color channel and third data corresponding to a third color channel;

an electronic processor programmed for;

weighting the first data, the second data and the third data according to at least the following two factors;

i) a color direction biased toward an anticipated embedding direction; and

ii) anticipated image or video distortion introduced to the first data, second data or third data through scanning or signal processing; and

determining from weighted first data, weighted second data and weighted third data, changes in an image or video attribute, in which the auxiliary information is conveyed through the changes to sample values representing the image or video.

22. The apparatus of claim 21 in which the electronic processor is operating to perform at least one of the functions recited therein.