Digital watermarking


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Digital watermarking

  1. 1. Digital Image Watermarking <ul><li>Presented By:- </li></ul><ul><li>Mohd Nafees Ansari </li></ul><ul><li>08peb-247 </li></ul><ul><li>Mohammad Mukeel </li></ul><ul><li>08peb-306 </li></ul><ul><li>Under Supervision of </li></ul><ul><li>Mr. Izharuddin </li></ul><ul><li> (Reader in Computer engg. Dept) </li></ul>
  2. 2. <ul><li>What is Digital Image Watermarking? </li></ul><ul><li>Digital Image Watermarking is a technique for inserting information (the watermark) into an image, which can be later extracted or detected for variety of purposes including identification and authentication purposes. </li></ul><ul><li>Why Need ? </li></ul>
  3. 3. Requirements <ul><li>Hardware Requirements: </li></ul><ul><li>-RAM :512MB </li></ul><ul><li>-Hard disk :4.0GB </li></ul><ul><li>Software Requirements: </li></ul><ul><li>-Operating system : Windows7 </li></ul><ul><li> -Language : Matlab </li></ul><ul><li>Cover Image & message image : Grayscale image </li></ul><ul><li>Size of cover image is greater than the message image </li></ul>
  4. 4. A digital watermark can be. <ul><ul><li>Visible Watermark </li></ul></ul><ul><ul><li>In visible watermarking , the information is visible in the picture or </li></ul></ul><ul><ul><li>video. The information is text or a logo which identifies the owner of the media. </li></ul></ul><ul><ul><li>Invisible Watermark </li></ul></ul><ul><li>In invisible watermarking , information is added as digital data to audio, picture or video, but it cannot be perceived as such (although it may be possible to detect that some amount of information is hidden). </li></ul>
  5. 5. Watermarking Domain <ul><li>Spatial Domain </li></ul><ul><li>Wavelet Domain </li></ul><ul><li>Frequency Domain </li></ul>
  6. 6. <ul><li>Spatial Domain Approach: </li></ul><ul><li>The earliest watermarking techniques are mainly this kind and the simplest example is to embed the watermark into least significant bits(LSB) of the image pixels. </li></ul><ul><li>This technique has relatively low information hiding capacity and can be easily erased by lossy image compression. </li></ul>
  7. 7. Wavelet Domain <ul><li>The DWT (Discrete Wavelet Transform) separates an image into a lower resolution approximation image (LL) as well as horizontal (HL), vertical (LH) and diagonal (HH) detail components. The process can then be repeated to computes multiple “scale” wavelet decomposition, as in the 2 scale wavelet transform shown below in figure </li></ul>
  8. 8. <ul><li>FREQUENCY DOMAIN APPROACH </li></ul>
  9. 9. Digital Watermarking Process
  10. 10. FEATURES OF DIGITAL WATERMARKING <ul><li>Imperceptibility (slight change) </li></ul><ul><li>Robustness </li></ul><ul><li>Inseparability </li></ul><ul><li>Security </li></ul>
  11. 11. Classifications of digital watermarking <ul><li>Robust watermark </li></ul><ul><li>It sticks to document ( image, audio, video or text) to which it is embedded. Removing it destroys the quality of signal. It is used for copyright protection. </li></ul><ul><li>Fragile Watermark </li></ul><ul><li>It breaks very easily on modifying host signal. It is used for temper detection, finger printing and digital signature. </li></ul><ul><li>Semi Fragile Watermark </li></ul><ul><li>It is sensitive to signal modification and gives information about nature and location of attack also, it provides data authentication. </li></ul>
  12. 12. Least Significant Bit <ul><li>It is based on the substitution of LSB plane of the cover image with the given watermark. </li></ul><ul><li>Embedding watermark: </li></ul><ul><li>Read the cover image. </li></ul><ul><li>Determine the size of the cover image. </li></ul><ul><li>Read the message image. </li></ul><ul><li>Determine the size of the message image. </li></ul><ul><li>Take pixel value of cover image. </li></ul><ul><li>Convert into binary. </li></ul><ul><li>Replaces the LSB of cover image with the binary value of bits of message image . </li></ul><ul><li>Recover Watermark: </li></ul><ul><li>Thereafter, make a function that extracts your watermark from a watermarked image. The function should take as input a watermarked image and give the extracted watermark as output. </li></ul>
  13. 14. Recover watermark in LSB
  14. 15. Watermark in wavelet domain <ul><li>Watermark insertion </li></ul><ul><li>Set the gain factor for embedding. </li></ul><ul><li>Read in the cover object. </li></ul><ul><li>Determine size of watermarked image. </li></ul><ul><li>Read in the message image and reshape it into a vector. </li></ul><ul><li>Add PN-sequences to h1 and v1 components when message = 0, according to the formula: </li></ul><ul><li>Perform IDWT. </li></ul><ul><li>Convert back to uint8. </li></ul><ul><li>Write watermarked image to file. </li></ul><ul><li>Display watermarked image. </li></ul>
  15. 17. Watermark extraction <ul><li>Read in the watermarked object. </li></ul><ul><li>Determine size of watermarked image. </li></ul><ul><li>Read in original watermark. </li></ul><ul><li>Determine size of original watermark. </li></ul><ul><li>Initialize message to all ones. </li></ul><ul><li>Add PN-sequences to h1 and v1 components </li></ul><ul><li>when message = 0. </li></ul><ul><li>Reshape the message vector and display </li></ul><ul><li>recovered watermark. </li></ul><ul><li>Display recovered message. </li></ul><ul><li>Calculate the quality of recovered image by </li></ul><ul><li>using PSNR function </li></ul>
  16. 18. <ul><li>FUTURE DEVELOPMENT </li></ul><ul><li>In this project we use a gray scale image for watermark image to insert into original image. In future, we use a color images. </li></ul><ul><li>Watermarking in Discrete Wavelet Transform domain. </li></ul><ul><li>Watermarking in Discrete Cosine Transform (DCT) domain. </li></ul>
  17. 19. Applications <ul><li>Documents and image security </li></ul><ul><li>Copyright protection </li></ul><ul><li>Copy Protection </li></ul><ul><li>Content Authentication </li></ul><ul><li>Broadcast monitoring </li></ul><ul><li>Digital Fingerprinting </li></ul><ul><li>Temper Detection </li></ul>
  18. 20. References <ul><li>http:// </li></ul><ul><li>  </li></ul><ul><li> -- An online help for working in MATLAB. </li></ul><ul><li>An Introduction to Digital Image Processing with Matlab </li></ul><ul><li>Matlab An introduction with Applications by Amos Gilat. </li></ul>
  19. 21. Thank You