Digital water marking


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Digital water marking

  1. 1. DIGITAL WATERMARKING Shashwat Shriparv
  2. 2. 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.
  3. 3. Introduction  Advantages of Digital Data  Copy right problems with digital data  Encryption & Decryption  Problems with Encryption & Decryption
  4. 4. Conventional Encryption System
  5. 5. 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?
  6. 6. Example of a conventional watermark Courtesy of Blue Spike, Inc.
  7. 7. Digital Watermarking is originated from Steganography
  8. 8. 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
  9. 9. 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
  10. 10. Behind The Technology Sending Side … Watermark Embedding process  Water mark  Original message  Key  Water marked image
  11. 11. Behind The Technology Watermark retrieval process  Water marked image  Key  Confidential message Receiving Side …
  12. 12. The Overall System The Technology Roars…
  13. 13. Importance Of Digital Watermarking © Copyright Information © On-line music industry © News gathering using digital cameras
  14. 14. Types of Digital Watermarking.  Robust & Fragile Watermarking  Visible & Invisible Watermarking  Public & Private Watermarking  Asymmetric & Symmetric Watermarking  Steganograhic & Non- Steganographic watermarking Variety Adds…
  15. 15. 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
  16. 16. Visible & Invisible Watermarking  On Visible watermarking, contents are visible
  17. 17. Visible & Invisible Watermarking (Contn..)  Invisible watermarking are not viewed on just looking
  18. 18. Public & Private Watermarking • Public Watermarking Users of content are authorized to detect watermark • Private Watermarking Users not authorized to detect watermark
  19. 19. Asymmetric & Symmetric watermarking  In Asymmetric watermarking different keys used for embedding and detecting watermark
  20. 20. Asymmetric & Symmetric watermarking (Contn..)  In symmetric watermarking same keys are used for embedding and detecting watermarks
  21. 21. Steganographic & Non- Steganographic 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
  22. 22. Digital Watermarking Techniques  LSB Watermarking  Color Separation Technique  Bit Stream Watermarking  Word Space Coding, Line Space Coding &Character Coding
  23. 23. 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
  24. 24. Color Separation Technique  Watermark appears only in one of the color bands  Used to watermark in still images  Can be extended to moving images
  25. 25. Bit Stream Watermarking  Used in audio watermarking  Data is directly inserted into compressed audio files
  26. 26. 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).
  27. 27. Features of Digital Watermarking  Imperceptibility  Robustness  Security
  28. 28. Applications of Digital Watermarking.  Copy Protection  Content Authentication  Copyright Protection  Metadata Tagging
  29. 29. Copy Protection  It limits the access to copyrighted material and inhibit the copy process
  30. 30. 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.
  31. 31. Content Authentication
  32. 32. Copyright Protection  One of the main application  Embedding watermarks in digital photographs
  33. 33. 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.
  34. 34. Attacks to Digital Watermarking  Stirmark  Mosaic Attack
  35. 35. 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
  36. 36. Stirmark Example
  37. 37. 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.
  38. 38. Mosaic Attack Example
  39. 39. 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
  40. 40. 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.
  41. 41. References  
  42. 42. Shashwat Shriparv InfinitySoft