1. 基於(7,4)漢明碼的隱寫技術 Chair Professor Chin-Chen Chang (張真誠)
National Tsing Hua University
National Chung Cheng University
Feng Chia University

2. Introduction Information Hiding Hiding system Stego image Cover image
Secret message

3. Introduction (Cont.)
Cover Carriers
Image
Video
Sound
Text

4. ?
Data:
Data:
Corrected data:
Sender
Receiver

5. (7, 4) Hamming Coding Encoding p1 p2 d1 p3 d2 d3 d4 Encoding
d1 d2 d3 d4
Encoding
Data:
d2  d3  d4 = p3
1  0  1 = 0
d1  d2  d4 = p1
1  1  1 = 1
d1  d3  d4 = p2
1  0  1 = 0
p1 p2 d1 p3 d2 d3 d4
Encoded data

6. (7, 4) Hamming Coding (Cont.)
Error Detection
Error bit
Received data:
Correcting
Corrected data:
Error Position
Parity check matrix H

7. (7, 4) Hamming Coding (Cont.)
The (7,4) Hamming code can be applied to data hiding based on the pixel domain and AMBTC domain.

8. Matrix Coding Method = [0010100]
Example: [7,4] Hamming code, the parity check matrix H is :
Embedding process: Cover vector
Stego vector y = Change one bit in x according to coset leader associated to syndrome
= Change one bit in x according to coset leader associated to
= Change one bit in according to coset leader associated to
= [ ]
Extraction process:

9. Matrix Coding Method – based on the pixel domain
Embedding 11 10 9 6 3 4 12
Cover Image 10 9 6 3 4 12 11
( )T = (1 1 1)T
Stego Image
0 0 1 
Secret data: …
Parity check matrix H

10. Matrix Coding Method (Cont.) – based on the pixel domain
Extracting 10 9 6 3 4 12 11
Stego Image
( )T = (1 1 0)T
Extracted secret data: …
■ 7 pixels embed 3 bits

11. Matrix Coding Method – based on the AMBTC algorithm
248 76 49 62 57 24 96
118
125
144 56 41 82 97
211
114

12. Matrix Coding Method – based on the AMBTC algorithm
AMBTC algorithm (Absolute moment block truncation coding)
248 76 49 62 57 24 96
118
125
144 56 41 82 97
211
114 1
160 64
Original block
0/1 bitmap
Reconstructed block
Average=100
High mean value = 160
Low mean value = 64

13. The flowchart of the proposed scheme – embedding phase

14. An example of the proposed scheme – embedding phase

15. An example of the proposed scheme – embedding phase
Embed secret into the bitmaps

16. An example of the proposed scheme – embedding phase
Embed secret into (H, L)
Final Result

17. An example of the proposed scheme – extraction phase
Extract secret from bitmaps

18. An example of the proposed scheme – extraction phase
Extract secret from quantization pairs

19. Experimental results
Test images

20. Chuang and Chang’s scheme
Experimental results
Scheme
Criteria
Lena
Zelda
Elain
Jet
Boat
Goldhill
Average
AMBTC
PSNR (dB)
33.23
36.74
33.83
33.25
31.76
32.87
33.61
Proposed scheme
28.92
32.25
29.41
28.11
27.56.
28.74
29.17
HC (bits)
169,250
168480
172,479
168,388
170,103
172,771
170,245
Chang et al.’s scheme
[1]
30.71
34.26
31.26
30.99
31.02
30.49
31.45
114,688
Chuang and Chang’s scheme
[2]
30.45
33.98
31.07
30.52
29.84
31.06
13,051
13,169
13,248
12,637
11,989
12,486
12,763
[1] C.C. Chang, Y.J. Liu, and S.T. Nguyen, “Hiding Secret Information in Block Truncation Code Using Dynamic Programming Strategy,” In Proceedings of 6th International Graphic and Image Processing, vol. 9443, Beijing, China, 2014.
[2] J.C. Chuang and C.C. Chang, “Using a simple and fast image compression algorithm to hide secret information,” International Journal of Computers & Applications, vol. 28, no. 4, pp , 2006.

21. Conclusions
Based on the property of Hamming code, the embedding and the extracting are very simple.
The proposed steganographic scheme achieves much higher payload with a slightly lower visual quality of stego images compared with the related works.