Arrangement for embedding subliminal data in imaging
Various improvements to steganographic systems, and applications therefore, are disclosed. The improvements include facilitating scale and rotation registration for steganographic decoding by use of rotationally symmetric steganographically embedded patterns and subliminal digital graticules; improved techniques for decoding without access to unencoded originals; improving robustness of steganographic coding in motion pictures and/or in the presence of lossy compression/decompression; and representing data by patterned bit cells whose energy in the spatial domain facilitates decoding registration. Applications include enhanced-security financial transactions, counterfeit resistant identification cards, fraud deterrent systems for cellular telephony, covert modem channels in video transmissions, photo duplication kiosks with automatic copyright detection, and hotlinked image objects (e.g. with embedded URLs) for use on the internet.
1. A method for embedding a message into a digital image signal comprising:
providing a digital message;
providing at least one carrier;
multiplying the digital message with the at least one carrier and accumulating a result of the multiplying to form a composite signal; and
combining the composite signal with the digital image signal to form an image signal with an embedded digital message.
2. The method of claim 1 wherein the at least one carrier comprises a random carrier.
3. The method of claim 1 wherein the multiplying and accumulating spatially distributes the message in the composite signal.
4. The method of claim 1 wherein the digital image signal comprises video.
5. A method for embedding a message into a digital image signal comprising:
providing a digital message;
providing at least one carrier;
modulating the carrier according to the digital message to form a modulated carrier; and
combining the modulated carrier signal with the digital image signal to form an image signal with an embedded digital message, wherein the message is redundantly embedded and spatially distributed in the image signal.
6. The method of claim 5 wherein the modulating comprises modifying polarity of the carrier.
7. The method of claim 5 including providing a plurality of carriers.
8. The method of claim 5 wherein the at least one carrier is random.
9. The method of claim 5 wherein the at least one carrier comprises a pattern.
10. The method of claim 9 including filtering the at least one Carrier.
11. The method of claim 5 including convolving the carrier.
12. The method or claim 11 including convolving the carrier with a filter.
13. The method of claim 5 including adapting the modulated carrier to characteristics of the digital image.
14. The method of claim 13 wherein the modulated carrier is perceptually adapted to the digital image according to a non-linear function of die characteristics.
15. The method of claim 5 wherein the modulating makes the message redundant and spatially distributed.
16. The method of claim 5 wherein the digital image signal comprises video.