1. Program Homework Implementation of the Improved Spread Spectrum Watermarking System

2. 2 Reference Ingemar J. Cox, Joe Kilian, F. Tomson Leighton, and Talal Shamoon, “Secure Spread Spectrum Watermarking for Multimedia,” IEEE Trans. On Image Processing, vol. 6, no. 12, December 1997 H. S. Marvar and A. F. Florencio, "Improved Spread Spectrum: A New Modulation Technique for Robust Watermarking," IEEE Trans. on Signal Processing, vol. 51, no. 4, April 2003

3. Basic Knowledge 2-D DCT DCT pattern for an 8x8 block https://en.wikipedia.org/wiki/Discrete_cosine_transform 3 Middle Band Low Band High Band

4. Spread-Spectrum Watermarking

5. Spread Spectrum 5

6. Define The watermark W = b 1 b 2 … b n ( ex. n = 1000 ) b i ~ N(0,1) Use Sign(.) to convert b i into 1 or -1 The Cover Image C is transformed by N×N DCT. C t =DCT(C). The coefficients to be altered X = x 1 x 2 … x m (m coefficients in the C t except DC, m: extract pattern length) How to choose X: many heuristics In zigzag order choose an interval length = m Max m coefficients in zigzag order Random sample m coefficients m coefficients with largest DCT value … 6

7. Spread Spectrum 7

8. 8

9. 9 Low Band High Band

10. Spread Spectrum 10 α = 0.1~100

11. Spread Spectrum 11 Low Band High Band

12. Spread Spectrum 12

13. Spread Spectrum So far, we can embed just “1” bit message into image But, how can we embed “n” bits? 3 Ways Code division Use different extract pattern(orthogonal extract patterns are suggest) Frequency division Embed message into different frequency band Spatial division Slice image into many blocks each block embeds 1 bit message 13

14. Improved Spread-Spectrum Watermarking

15. Improved Spread Spectrum Define The watermark W = b 1 b 2 … b n ( ex. n = 1000 ) b i ~ N(0,1) Use Sign(.) to convert b i into 1 or -1 The Cover Image C is transformed by N×N DCT. C t =DCT(C). The coefficients to be altered X = x 1 x 2 … x m (m coefficients in the C t except DC, m: extract pattern length) How to choose X: many heuristics In zigzag order choose an interval length = m In this homework we suggest you to use it Max m coefficient in zigzag order Random sample m coefficient m coefficient with largest DCT value … 15

16. Improved Spread Spectrum 16

17. Improved Spread Spectrum 17

18. Improved Spread Spectrum 18 Low Band High Band

19. Improved Spread Spectrum 19 α = 0.1~100 λ = around 1

20. Improved Spread Spectrum 20

21. Improved Spread Spectrum So far, we can embed just “1” bit message into image But, how can we embed “n” bits? 3 Ways Code division Use different extract pattern(orthogonal extract patterns are suggest) Frequency division Embed message into different frequency band Spatial division Slice image into many blocks each block embeds 1 bit message In this homework we use this method 21

22. Measurements We always have three dimensions in measurement stage Capacity Fidelity Robustness When measuring one dimension, you must fix the others When compare two dimensions, you must fix the other 22

23. Measurements Measurements for Capacity Amount of message that embedded in cover image How to improve capacity The more blocks you slice the original image, the more bits you can embed into it As you know, code division, frequency division methods can also achieve capacity requirement. 23

24. Measurements Measurements for Fidelity Quality of watermarked image Use PSNR value between original image and marked image Reference website https://en.wikipedia.org/wiki/Peak_signal-to-noise_ratio Code: Call PSNR(imageA, imageB) in MATLAB or Find PSNR code in web and use it How to improve fidelity Consider influence of cover images not just use additive operation to add watermark into it Consider Human Visual System(ex: perceptual model) Embedding in other domain(ex: wavelet based approach) 24

25. Measurements 25

26. 26 Attacks Lossy Compression JPEG compression Geometric Distortion Rotation Shifting Scaling Affine transform Cropping Image Processing Blurring …

27. Homework1 Rules Deadline: 2015/11/30 14:00 (suggest) Before the week of final exam(I will strictly grade your score) Hand-in instructions: Program: MATLAB code(suggest), other languages are welcome(if I cannot run your code, I will ask you to perform your program with your own laptop) Report: PDF file(strongly suggest), others are welcome(but if my computer cannot open it, you will get 0 score) Zip all program files, reports into one file and sent to gary810410@cmlab.csie.ntu.edu.tw gary810410@cmlab.csie.ntu.edu.tw Title the mail as: [MMSEC]2015HW1_studentID Name the attached file as: [MMSEC]2015HW1_studentID.zip studentID example: R03944006 27

28. Homework1 Grading Criteria Program (30%): embed and extract ISS functions A main program to perform embed and extract process Report (70%): How to execute your code Any special method you implement besides the basic ISS scheme Test parameters used in ISS scheme Test capacity, fidelity and robustness of your watermarking scheme Compare Improved Spread Spectrum with Spread Spectrum Compare the influence of attacks on your watermarking scheme At least 6 types of attacks Others 28

29. Homework1 29

30. Bonus Please propose a blind watermarking scheme of Chiou- Ting Hsu and Ja-Ling Wu, "Hidden Digital Watermarks in Images," IEEE Trans. On Image Processing, Vol.8, No.1, pp.58~68 January. 1999. P.S. You can write down your opinions of the new scheme only Coding for the new scheme is welcome 30

31. Advanced Reading Watermarking on other multimedia No limitation on multimedia materials. References: Video “Digital Video Watermarking in P-Frames with Controlled Video Bit-Rate Increase”, IEEE Transactions on Information Forensics and Security, 2008. “Blind MPEG-2 Video Watermarking Robust Against Geometric Attacks: A Set of Approaches in DCT Domain”, IEEE Transactions on Image Processing, 2006. Audio “Spread-Spectrum Watermarking of Audio Signals”, IEEE Transactions on Signal Processing, 2003. “Watermarked Movie Soundtrack Finds the Position of the Camcorder in a Theater”, IEEE Transactions on Multimedia, 2009. Graphics “Watermarking Three-Dimensional Polygonal Models Through Geometric and Topological Modifications”, IEEE Journal on Selected Areas in Communications, 1998. Text “Data Hiding in Binary Image for Authentication and Annotation”, IEEE Transactions on Multimedia, 2004. 31