Method and system for embedding message data in a digital image sequence

1. A method for embedding message data in an image sequence having two or more frames, comprising the steps of:

a) providing a dispersed message image representative of the message data;

b) producing a cyclically shifted version of the dispersed message image corresponding to a spatial offset;

c) combining the cyclically shifted version of the dispersed message image with a frame of the image sequence; and

d) repeating steps b) and c) for one or more additional frames of the image sequence.

2. The method claimed in claim 1 , wherein the step of producing a cyclically shifted version of the dispersed message image includes the steps of:

a1) producing a message image representing the message data;

a2) providing a carrier image;

a3) convolving the message image with the carrier image to produce a dispersed message image; and

a4) cyclically shifting the dispersed message image by a spatial offset to produce a cyclically shifted version of the dispersed message image.

3. The method claimed in claim 1 , wherein the cyclically shifted dispersed message images are not visible when added to the frames of the image sequence.

4. The method claimed in claim 2 , wherein the carrier image has random phase and substantially flat Fourier amplitude.

5. The method claimed in claim 1 wherein the cyclically shifted versions of the dispersed message image are shifted randomly for successive frames.

6. The method claimed in claim 1 , further comprising the steps of:

e) determining the spatial shift corresponding to each cyclically shifted version of the dispersed message image in a plurality of frames;

f) aligning the plurality of frames based on the determined spatial shifts corresponding to the respective dispersed message images and combining the aligned frames to produce a combined frame; and

g) extracting the message image from the combined frame.

7. The method claimed in claim 2 , further comprising the steps of:

e) determining the spatial shift corresponding to each cyclically shifted version of the dispersed message image in a plurality of frames;

f) aligning the plurality of frames based on the determined spatial shifts corresponding to the respective dispersed message images and combining the aligned frames to produce a combined frame; and

g) extracting the message image from the combined frame by correlating the carrier image with the combined frame.

8. A system for embedding message data in an image sequence having two or more frames, comprising:

a) means for providing a dispersed message image representative of the message data;

b) means for producing a cyclically shifted version of the dispersed message image corresponding to a spatial offset;

c) means for combining the cyclically shifted version of the dispersed message image with a frame of the image sequence; and

d) means for repeating initiating repetition of the means for producing and means for combining.

9. The system claimed in claim 8 , wherein the means for producing a cyclically shifted version of the dispersed message data image includes:

a1) means for producing a message image representing the message data;

a2) means for providing a carrier image;

a3) means for convolving the message image with the carrier image to produce the dispersed message image; and

a4) means for cyclically shifting the dispersed message image by a spatial offset to produce a cyclically shifted version of the dispersed message image.

10. The system claimed in claim 8 , wherein the cyclically shifted versions of the dispersed message image are not visible when added to the frames of the image sequence.

11. The system claimed in claim 9 , wherein the carrier image has random phase and substantially flat Fourier amplitude.

12. The system claimed in claim 8 wherein the means for cyclically shifting the dispersed message image employs random spatial shifts.

13. The system claimed in claim 8 , further comprises:

e) means for determining the spatial shift corresponding to each cyclically shifted version of the dispersed message image in a plurality of frames;

f) means for aligning the plurality of frames based on the determined shift applied spatial shifts corresponding to the respective dispersed message images and combining the aligned frames to produce a combined frame; and

g) means for extracting the message image from the combined frame.

14. The system claimed in claim 9 , further comprises:

e) means for determining the spatial shift corresponding to each cyclically shifted version of the dispersed message image in a plurality of frames;

f) means for aligning the plurality of frames based on the determined spatial shifts corresponding to the respective dispersed message images and combining the aligned frames to produce a combined frame; and

g) means for extracting the message image from the combined frame by correlating the carrier image with the combined frame.

15. The method claimed in claim 1 , wherein the step of producing a cyclically shifted version of the dispersed message image includes the steps of:

a1) producing a message image representing the message data;

a2) cyclically shifting the message image by a spatial offset to produce a cyclically shifted message image;

a3) providing a carrier image; and

a4) convolving the cyclically shifted message image with the carrier image to produce a cyclically shifted version of the dispersed message image.

16. The method claimed in claim 1 , wherein the step of producing a cyclically shifted version of the dispersed message image includes the steps of:

a1) producing a message image representing the message data;

a2) providing a carrier image;

a3) cyclically shifting the carrier image by a spatial offset to produce a cyclically shifted carrier image; and

a4) convolving the message image with the cyclically shifted carrier image to produce a cyclically shifted version of the dispersed message image.