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  • 1. DIGITAL WATERMARKING Sejal Visawadia
  • 2. Watermark What is Watermarking? “ 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.
  • 3. Example of a conventional watermark Courtesy of Blue Spike, Inc.
  • 4. Digital Watermark “ Digital watermarking is similar to watermarking physical objects, except that the watermarking technique is used for digital content instead of physical objects.”
  • 5. Digital Watermark (Cont..) 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
  • 6. Behind The Technology Sending Side … Watermark Embedding process  Water mark  Original message  Key  Water marked image
  • 7. Behind The Technology Receiving Side … Watermark retrieval process   Water marked image Key  Confidential message
  • 8. The Overall System The Technology Roars…
  • 9. Importance Of Digital Watermarking © Copyright Information © On-line music industry © News gathering using digital cameras
  • 10. Types of Digital Watermarking      Robust & Fragile Watermarking Visible & Invisible Watermarking Public & Private Watermarking Asymmetric & Symmetric Watermarking Steganograhic & NonSteganographic watermarking
  • 11. 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
  • 12. Visible & Invisible Watermarking  On Visible watermarking, contents are visible
  • 13. Visible & Invisible Watermarking (Cont..)  Invisible watermarking are not viewed on just looking
  • 14. Public & Private Watermarking • Public Watermarking Users of content are authorized to detect watermark • Private Watermarking Users not authorized to detect watermark
  • 15. Asymmetric & Symmetric watermarking  In Asymmetric watermarking different keys used for embedding and detecting watermark
  • 16. Asymmetric & Symmetric watermarking (Cont..)  In symmetric watermarking same keys are used for embedding and detecting watermarks
  • 17. Steganographic & NonSteganographic Watermarking  Steganographic Watermarking User unaware of the presence of a watermark eg:-Used in finger printing applications  Non-Steganographic WM:User aware of the presence of a watermark. e.g.:-User to detect piracy
  • 18. Digital Watermarking Techniques  LSB Watermarking  Color Separation Technique  Bit Stream Watermarking  Word Space Coding, Line Space Coding &Character Coding
  • 19. 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
  • 20. Color Separation Technique  Watermark appears only in one of the color bands  Used to watermark in still images  Can be extended to moving images
  • 21. Bit Stream Watermarking  Used in audio watermarking  Data is directly inserted into compressed audio files
  • 22. 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).
  • 23. Applications of Digital Watermarking Copy Protection  Content Authentication  Copyright Protection  Metadata Tagging 
  • 24. Copy Protection  It limits the access to copyrighted material and inhibit the copy process
  • 25. 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.
  • 26. Content Authentication
  • 27. Copyright Protection  One of the main application  Embedding watermarks in digital photographs
  • 28. 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.
  • 29. Attacks to Digital Watermarking   Stirmark Mosaic Attack
  • 30. 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
  • 31. Stirmark Example
  • 32. 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. 
  • 33. Mosaic Attack Example
  • 34. 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
  • 35. 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.
  • 36. THANK YOU