影像偽裝術的最新發展

1. 影像偽裝術的最新發展 張真誠 逢甲大學 講座教授 中正大學 榮譽教授 清華大學 合聘教授

2. Watermarking • Image authentication • Secret sharing • Visual cryptography • Steganography

3. Watermarking • Visible watermarking • Easy to embed • Clear to see watermark

4. Watermarking (Cont.) • Invisible watermarking • Requirements: • Good visual quality of watermarked image • Robustness Watermarking Original image Watermarked image Watermark

5. Image authentication • Requirements: • Detect the tampered area • Try to restore the tampered area Tampered image Detected image Restored image Image

6. Secret sharing • Classification: • Meaningless shadows • Meaningful shadows

7. Secret sharing (Cont.) Sharing Shadow size: 256  256 Image size: 512  512 Reconstructing (2,4)-threshold secret sharing scheme PSNR=24 dB

8. Secret sharing (Cont.) Reconstructing Hiding Stego-image Reconstructed secret image Secret image Stego-image (2, n)-threshold secret sharing scheme Stego-image

9. Visual cryptography Stacking Shadow 1 Shadow 2 Secret

10. Visual cryptography (Cont.) Stacking Shadow 1 Shadow 2 Secret

11. Visual cryptography (Cont.) Rotating 40o Stacking Stacking Share 2 Share 1 Secret 1 “VISUAL” Secret 2 “SECRET”

12. Steganography • The targets • Frequency domain (e.g. DCT, DWT, DFT) • Spatial domain (e.g. pixel values) • Compression domain (e.g. VQ) • Text • Restoration • Irreversible • Reversible

13. Hiding system Stego image Cover image 1 0 1 0 1 0 0 1 0 1 1 1 1 0 0 Secret message Steganography (Cont.) • Image

14. Steganography (Cont.) • Text 壞的毛病 壞毛病 山東的蘋果 山東蘋果 我的媽媽 我媽媽 主要的問題 主要問題 另外的一件事 另外一件事 其他的問題 其他問題 北京的大學 北京大學 • Video • Sound

15. Zhang and Wang’s Method(Embedding) Secret data:1000 1011… p2 255 0 1 2 3 4 0 1 2 3 4 0 1 10002 1 35 : : : : : : : : : : : : : … 11 2 3 4 0 1 2 3 4 0 1 2 3 2 … 10 0 1 2 3 4 0 1 2 3 4 0 1 0 Cover image … 9 3 4 0 1 2 3 4 0 1 2 3 4 3 … 8 1 2 3 4 0 1 2 3 4 0 1 2 1 … 7 4 0 1 2 3 4 0 1 2 3 4 0 4 … 6 2 3 4 0 1 2 3 4 0 1 2 3 2 … 5 0 1 2 3 4 0 1 2 3 4 0 1 0 … 4 3 4 0 1 2 3 4 0 1 2 3 4 3 … 3 1 2 3 4 0 1 2 3 4 0 1 2 1 … 2 4 0 1 2 3 4 0 1 2 3 4 0 4 … 1 2 3 4 0 1 2 3 4 0 1 2 3 2 … 0 0 1 2 3 4 0 1 2 3 4 0 1 0 Stego image p1 0 1 2 3 4 5 6 7 8 9 10 11 … 255 Magic Matrix

16. Zhang and Wang’s Method (Extracting) p2 255 0 1 2 3 4 0 1 2 3 4 0 1 : : : : : : : : : : : : : … 11 2 3 4 0 1 2 3 4 0 1 2 3 2 … 10 0 1 2 3 4 0 1 2 3 4 0 1 0 … 9 3 4 0 1 2 3 4 0 1 2 3 4 3 … 8 1 2 3 4 0 1 2 3 4 0 1 2 1 Stego image … 7 4 0 1 2 3 4 0 1 2 3 4 0 4 … 6 2 3 4 0 1 2 3 4 0 1 2 3 2 … 5 0 1 2 3 4 0 1 2 3 4 0 1 0 … 4 3 4 0 1 2 3 4 0 1 2 3 4 3 … 3 1 2 3 4 0 1 2 3 4 0 1 2 1 … 2 4 0 1 2 3 4 0 1 2 3 4 0 4 … 135 1 2 3 4 0 1 2 3 4 0 1 2 3 2 … 0 0 1 2 3 4 0 1 2 3 4 0 1 0 p1 0 1 2 3 4 5 6 7 8 9 10 11 … 255 Magic Matrix Extracted secret data: 10002

17. Sudoku • A logic-based number placement puzzle

18. Sudoku (Cont.) • A Sudoku grid contains nine 3 × 3 matrices, each contains different digits from 1 to 9. • Each row and each column of a Sudoku grid also contain different digits from 1 to 9. • Property Possible solutions: 6,670,903,752,021,072,936,960 (i.e. ≈ 6.671×1021)

19. Data Hiding Using Sudoku - 1 Reference Matrix M

20. Data Hiding Using Sudoku (Embedding) (Cont.) Secret data:011 001 10… 279 Cover Image min. d( , ) = ((8-8)2+(4-7)2)1/2=3 d( , ) = ((9-8)2+(7-7)2)1/2=1 d( , ) = ((6-8)2+(8-7)2)1/2=2.24 Stego Image

21. Data Hiding Using Sudoku (Embedding) (Cont.) Secret data:011 001 10… 279 Cover Image d( , ) = ((11-11)2+(15-12)2)1/2=3 d( , ) = ((15-11)2+(12-12)2)1/2=4 d( , ) = ((9-11)2+(14-12)2)1/2=2.83 min. Stego Image

22. Data Hiding Using Sudoku (Extracting) (Cont.) Stego Image Extracted data: 279 = 011 0012

23. Experimental Results

24. Experimental Results (Cont.) The results of visual quality and Embedding capacity comparisons