color image watermarking

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color image watermarking

  1. 1. OBJECTIVE To provide authenticity or the identity of ownership on images. Protecting digital images against un-authorized use, i.e. duplication, mis-representation and mis- distribution or illegal usage. main focus is to embed a color watermark image in to a color host image.
  2. 2. Introduction  Digital watermarking  The process of embedding digital information into a digital signal. - Purpose - Various types of Watermarking - Basic requirements  Invisible Fragile Image Watermarking.  Embed a color watermark image in a color Host Image.
  3. 3. Classification
  4. 4. Requirements :  The extracted watermark remains intact. i.e., image authentication is guaranteed.  Quality of generated watermarked image should improved. w.r.t. others.  The security issues related to the watermark are provided using a secret key and a hash function.
  5. 5. Ideal Properties perceptually invisible to prevent obstruction of original image. statistically invisible, so it can’t be detected or erased. extraction should be simple and accurate. the watermark should be able to determine the true ownership of the Image.
  6. 6. Features:  Transparency : Perceptual quality of data being protected.  Robustness : with stand against any intentional transformations.  Capacity : the ability to detect the watermarks with a low probability of error.
  7. 7. Process: Host image is divided in to some blocks. Embed watermark at LSB of Blue values of all such blocks . Manipulating only the ‘Blue values’(HVS). No. of host image blocks should be equal to the no. of bit embedded multiplied by the bit size of RGB.
  8. 8. Technique: 2-bit scheme Fig: Block diagram
  9. 9. Process diagram: 2-bit scheme
  10. 10. Technique : 1-bit scheme Fig: Block diagram
  11. 11. Process Diagram: 1-bit scheme
  12. 12. Algorithm: Embedding  get_blue pixel_info (Yi)  onebit_to_zero (Yip)  hash_for_mesg_digest (Li , K)  extract_onebit (A)  compute_XOR (Hi , Ai)  replace_(Yip , Xi )
  13. 13. Execution of Algorithm for Embedding watermark HOST IMAGE (Y) WATERMARK IMAGE (A)
  14. 14. H WATERMARK (A) O S T (Y) R G BR G B
  15. 15. get_blue pixel_info (Yi) B L U E P L A N E LSB-0 BLUE BIT PLANE (Ybi ) Dividing into Blocks8 BIT-PLANES ONEBIT_TO_ZERO (Li)
  16. 16. hash_for_mesg_digest (Li , K)Li Secret Key (K) MD5 1111000010101100 Applying HASH (Li ,K)
  17. 17. CO HMP AU ST HEXO XORR R LSB-0 BLUE BIT PLANE B G
  18. 18. replace_(Yip , Xi ) LSB-0 Blue bit-plane LSB-1 LSB-2 LSB-3 BLUE PLANE LSB-4 LSB-5 LSB-6 LSB-7
  19. 19. WATERMARKED IMAGE GREEN PLANE RED PLANE BLUE PLANE
  20. 20. Execution of Algorithm for Extracting watermark  onebit_to_zero (Wi)  hash_for_mesg_digest (L’i , K)  retrieve Wi  compute_XOR
  21. 21. Execution of Algorithm for Extracting watermark WATERMARKED R G B
  22. 22. B L U E P L A N E LSB-0 BLUE BIT PLANE (Wdbi ) Dividing into Blocks8 BIT-PLANES ONEBIT_TO_ZERO (Li)
  23. 23. L’i hash_for_mesg_digest (L’i , K) Secret Key (K) MD5 1111000010101100 Applying HASH (L’i ,K)
  24. 24. HASH XORLSB-0 BLUE BIT PLANE (Ri)
  25. 25. R G B Extracted watermark (A’i)
  26. 26. Observation : We can easily see that Ai= Ai. So our watermark image is retained intact (complete) after extraction, by combining all bit-planes from all blocks.Advantages:  Security  Persistency of Image Quality  At the time of extraction neither the host image nor the watermark image is needed.  Copyright Protection  Tamper Proof verification
  27. 27. CONCLUSION AND FUTURE SCOPE Among large variety of watermarking techniques, an attempt has been made to develop color image watermarking scheme for color images. Both host image and watermark images are color images. The extracted watermark remains intact, i.e. image authentication is guaranteed. As a future research scope attempt will be make to develop the framework to semi-fragile watermarking, to detect malicious manipulations on an image, while allowing acceptable manipulations.
  28. 28. Thank you

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