digital water marking
DESCRIPTION
TRANSCRIPT
Overview
Introduction What is Watermarking? What is Digital Watermarking? Behind the Technology. Importance Types of Watermarking. Digital Watermarking Techniques. Features of Digital Watermarking. Applications Attacks to Digital Watermarking. Conclusion.
Introduction
Advantages of Digital DataCopy right problems with digital dataEncryption & DecryptionProblems with Encryption & Decryption
Conventional Encryption System
Watermark
“ Watermarking can be considered as a special
technique of steganography where one message is embedded in another and the two messages are related to each other in some way. “
Example :-
The presence of specific patterns in currency notes which are visible only when the note is held to light is a well known example for watermark.
What is Watermarking?
Example of a conventional watermark
Courtesy of Blue Spike, Inc.
Digital Watermarking is originated from Steganography
What is Digital Watermarking?
“ Digital watermarking is similar to watermarking physical objects, except that the watermarking technique is used for digital content instead of physical objects. “
Digital Watermark
Digital Watermark (Contn..)
In digital watermarking a low-energy signal is imperceptibly embedded in another signal. The low-energy signal is called watermark.
The main signal in which the watermark is embedded is referred to as cover signal since it covers the watermark.
An entity called watermark key used for embedding and detecting watermark signal
Watermark key is private
Behind The Technology
Sending Side …
Watermark Embedding process Water mark Original message Key Water marked image
Behind The Technology
Watermark retrieval process Water marked image Key Confidential message
Receiving Side …
The Overall SystemThe Technology
Roars…
Importance Of Digital Watermarking
© Copyright Information© On-line music industry© News gathering using digital cameras
Types of Digital Watermarking.
Robust & Fragile Watermarking Visible & Invisible Watermarking Public & Private Watermarking Asymmetric & Symmetric
Watermarking Steganograhic & Non-
Steganographic watermarking
Variety Adds…
Robust & Fragile Watermarking
Robust Watermarking:-Modification of watermarked content will not affect watermark
Fragile Watermarking:-Watermark get destroyed when watermarked content is modified or tampered with
Visible & Invisible Watermarking
On Visible watermarking, contents are visible
Visible & Invisible Watermarking (Contn..)
Invisible watermarking are not viewed on just looking
Public & Private Watermarking
• Public Watermarking
Users of content are authorized to detect watermark
• Private Watermarking
Users not authorized to detect watermark
Asymmetric & Symmetric watermarking
In Asymmetric watermarking different keys used for embedding and detecting watermark
Asymmetric & Symmetric watermarking (Contn..)
In symmetric watermarking same keys are used for embedding and detecting watermarks
Steganographic & Non-Steganographic Watermarking
Steganographic Watermarking
User unaware of the presence of a watermark
eg:-Used in finger printing applicationsNon-Steganographic WM:-
User aware of the presence of a watermark.
e.g.:-User to detect piracy
Digital Watermarking Techniques
LSB Watermarking Color Separation Technique Bit Stream Watermarking Word Space Coding, Line Space Coding
&Character Coding
LSB Watermarking
Lower order bits of selected pixels in the image are used to store watermarks
Replacing lower order bits of each pixel with higher order bit of different image
Color Separation Technique
Watermark appears only in one of the color bands
Used to watermark in still images Can be extended to moving images
Bit Stream Watermarking
Used in audio watermarking Data is directly inserted into compressed
audio files
Word Space Coding, Line Space Coding &Character Coding
Used for watermarking in text documents In word space coding, the spaces between
words are altered to embed watermark code. In line space coding the space between the lines are altered and in character coding some of the characters are imperceptibly modified (i.e., made larger, serifs enhanced, etc).
Features of Digital Watermarking
Imperceptibility Robustness Security
Applications of Digital Watermarking.
Copy ProtectionContent AuthenticationCopyright ProtectionMetadata Tagging
Copy Protection
It limits the access to copyrighted material and inhibit the copy process
Content Authentication
Robust watermarks are used in this area
Example:-A photographic information that may be presented as evidence in court. Since digital images can be easily manipulated, there is a need to provide proof that an image has not been altered.
Content Authentication
Copyright Protection
One of the main application Embedding watermarks in digital
photographs
Metadata Tagging
Watermarks convey object specific information to users of the object.
Used to attach patient identification data to medical images, or to highlight regions of diagnostic significance.
Attacks to Digital Watermarking
Stirmark Mosaic Attack
Stirmark
It is tool developed to test the robustness of image marking system
Stirmark is commonly produced by printers and scanners
IBM researchers have recently announced a technique that defeats the stir mark attack.
Detects and measures the geometric distortions in images, and removes the distortion to restore image geometry
StirmarkExample
Mosaic Attack
Use of a web crawler Dividing into sub images with rendition
instructions Browser will be rearranging the sub images to
appear as the original Sub images will be sufficiently small that no
single image on its own will contain a recognizable mark.
Mosaic AttackExample
Conclusion
DRM systems and content management are important for protection of rights of digital multimedia creations that are distributed on the Internet. Digital watermarking is an effective technique for embedding rights information in digital multimedia data.
Digital watermark technology can be used in consumer electronic devices like digital still camera, digital video camera, DVD players, MP3 players, etc., for various applications like providing controlled access, preventing illegal replication and watermark embedding
Conclusion (Contd..)
Digital information can easily be disseminated and copied via global networks.
The future of digital watermarking relies on setting standards and creating applications so that creators of digital content can easily implement it.
References
www.watermarkingworld.org www.digital-watermark.com
