15-01-2013, 10:10 AM
Digital Watermarking
Digital Watermarking.pptx (Size: 3.39 MB / Downloads: 55)
WHAT IS A WATERMARK?
A watermark is a form, image or text that is impressed onto paper, which provides evidence of its authenticity.
A distinguishing mark impressed on paper during manufacture; visible when paper is held up to the light (e.g. $ Bill)
WHAT IS DIGITAL WATERMARKING?
Digital watermarking is an extension of watermarking concept in the digital world.
A digital watermark is a pattern of bits inserted into a digital image, audio or video file that identifies the file's copyright information (author, rights, etc.).
Steganography vs. Watermarking
The main goal of steganography is to hide a message m in some audio or video (cover) data d, to obtain new data d', practically indistinguishable from d, by people, in such a way that an eavesdropper cannot detect the presence of m in d'.
The main goal of watermarking is to hide a message m in some audio or video (cover) data d, to obtain new data d', practically indistinguishable from d, by people, in such a way that an eavesdropper cannot remove or replace m in d'.
Cryptography vs. Watermarking
Cryptography is the most common method of protecting digital content and is one of the best developed science.
However, encryption cannot help the seller monitor how a legitimate customer handles the content after decryption.
Digital watermarking can protect content even after it is decrypted.
Importance of Digital Watermarking
As seen above in Fig, Alice creates an original image and watermarks it before passing it to Bob. If Bob claims the image and sells copies to other people Alice can extract her watermark from the image proving her copyright to it.
The caveat here is that Alice will only be able to prove her copyright of the image if Bob hasn’t managed to modify the image such that the watermark is damaged enough to be undetectable or added his own watermark such that it is impossible to discover which watermark was embedded first.
Conclusion
The experimental results show that the proposed method is robust against approximately 70% of attacks.
For sure when compared with previous, it is found to be more robust against various attacks. It also refers significant advantage in terms of shorter processing time and the ease of hardware implementation than many common transform techniques.