Self-orienting watermarks

• US 6,625,297 B1
• Filed: 02/10/2000
• Issued: 09/23/2003
• Est. Priority Date: 02/10/2000
• Status: Expired due to Term

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Bradley, Brett A.
• Primary Examiner(s): Patel, Jayanti K.
• Application Number:
  US09/502,543
• Time in Patent Office: 1,321 Days
• Field of Search: 382/100, 382/115, 382/112, 382/135, 382/232, 382/212, 380/232, 380/54, 380/28, 380/31, 380/38, 250/228, 156/378, 358/475, 709/217
• US Class Current: 382/100
• 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: H04N 1/32203 Spatial or amplitude domain methods H04N1/32309 takes precedence
• 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 2201/3233 of authentication information, e.g. digital signature, watermark

Abstract

A watermarking method converts a watermark message into a Frequency Shift Keying (FSK) signal and embeds the FSK signal in a host signal. The spectral properties of the FSK watermark signal facilitate its detection, even in applications where the watermarked signal is corrupted. Because of these properties, the FSK watermark signal can perform the dual function of identifying the watermark'"'"'s presence and orientation in potentially corrupted media, and also conveying a hidden message in the host signal. Such a watermark may be referred to as a self-orienting watermark.

Claims

1. A method of embedding a digital watermark in a host signal comprising:

converting a message into a digital watermark signal having an attribute that orients the watermark in the host signal, wherein said converting step converts the message to an FSK signal and the attribute is a set of two or more FSK signaling frequencies of the FSK signal; and

applying the watermark signal to the host signal.

2. The method of claim 1 wherein a message is encoded by converting symbols of the message into signals at selected FSK signaling frequencies.

3. The method of claim 2 wherein the symbols are binary numbers.

4. A computer readable medium on which is stored software for executing the method of claim 1.

5. A method of embedding a digital watermark in an image comprising:

converting a message into a digital watermark signal having an attribute that orients the watermark in the image, wherein said converting step converts the message to an FSK signal and the attribute is a set of two or more signaling frequencies; and

applying the watermark signal to the image.

6. The method of claim 5 wherein the FSK signal comprises a one dimensional signal that varies over a spatial dimension and is applied to the image in the spatial domain.

7. The method of claim 5 wherein the FSK signal is redundantly encoded in different parts of the image.

8. The method of claim 5 wherein the watermark has two or more FSK signal components, each carrying a different message.

9. A method of embedding a digital watermark in an audio signal comprising:

converting a message into a digital watermark signal having an attribute that orients the watermark in the audio signal, wherein said converting step converts the message to an FSK signal; and

applying the message to the audio signal.

10. The method of claim 9 wherein the message is comprised of two or more symbols, and the symbols are converted to signals at selected FSK signaling frequencies.

11. The method of claim 9 wherein the FSK signal is applied to the audio signal in the temporal domain.

12. A method of embedding a digital watermark in a host signal comprising:

converting a message into a digital watermark signal having an attribute that orients the watermark in the host signal, wherein said converting step converts the message to an FSK signal and the attribute is an FSK signaling frequency; and

applying the watermark signal to the host signal.

13. The method of claim 12 wherein the signaling frequency facilitates detection of the scale of the watermark in the host signal.

14. The method of claim 12 wherein the signaling frequency facilitates detection of the rotation angle of the watermark in the host signal.

15. The method of claim 12 wherein the FSK signal has two or more components, each with a phase offset that facilitates detection of the position of the watermark in the host signal.

16. The method of claim 12 wherein the FSK signal has two or more components, each with a selected set of signaling frequencies, the components being arranged in the host signal so that the sets of signaling frequencies facilitate detection of the position of the watermark in the host signal.

17. The method of claim 12 wherein the message includes a known message that facilitates detection of the watermark in the host signal.

18. A method of decoding a digital watermark in a host signal, wherein the watermark comprises an FSK signal, and wherein the watermark includes a message that is encoded by converting symbols to selected FSK signaling frequencies, said method comprising:

using an attribute of the watermark to determine orientation of the watermark in a host signal, the attribute being used to determine orientation and to carry a message; and

decoding the watermark.

19. The method of claim 18 including:

reading a message encoded in the watermark.

20. The method of claim 18 wherein the attribute is a signaling frequency.

21. The method of claim 20 wherein the signaling frequency facilitates detection of scale of the watermark in the host signal.

22. The method of claim 20 wherein the signaling frequency facilitates detection of rotation angle of the watermark in the host signal.

23. The method of claim 18 wherein the watermark has two or more components, each having a phase offset;

and

using the phase offset to determine position of the message in the host signal.

24. The method of claim 18 wherein the watermark has two or more components, each having a set of FSK signaling frequencies;

and

using the signaling frequencies to determine position of the message in the host signal.

25. The method of claim 18 wherein the watermark includes a known message, and

using the known message to identify a position of the watermark in the host message.

26. The method of claim 18 wherein the host signal is an image signal.

27. The method of claim 18 wherein the host signal is an audio signal.