PSYCH221: A survey of digital watermarking techniques
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Introduction: Methods: Conclusion: Contacts: |
Conclusion
Conclusion and further research
This project described the development of digital watermarking techniques from the early methods to the more sophisticated techniques being explored recently. A surprising fact I discovered in the course of this report was that the original, "naive" LSB insertion method provided the same level of transparancy as the frequency-domain methods. Authors of more recent watermarking papers deride spatial-domain methods for being deprecated and lacking robustness. The advantages, however, appear to be a trade off. Frequency methods provide a good deal of robustness but lack the ability to store large amounts of arbitrary data, allowing instead a randomly generated "key". To authenticate a watermark, these algorithms frequently require some other data, such as the original, unencoded image. As is often the case, the choice of algorithm depends heavily on the application. Most papers I have read approach watermarking from a digital rights or authentication standpoint. These applications of digital watermarking are analagous to the traditional paper watermarks. The unique medium of digital imagery allows for applications that have no such analogue. For example, an audio watermark in an image sequence could be used to sync audio with video. Meta-data could be inserted into an image for database applications, while still allowing backwards compatibility with the JPEG standard. Unique IDs could be embedded into images to analyze the network traffic of a particular group of users. The field of watermarking is vast. Judging by the overwhelming number of publications, digital watermarking will undoubtedly have an important place in the way we exchange information in the future. |