1. Authors: Chin-Chen Chang, Yi-Hui Chen, and Chia-Chen Lin
Hiding Secret Information in a Color Palette Image with Hybrid Strategies
Authors: Chin-Chen Chang, Yi-Hui Chen, and Chia-Chen Lin
Speaker: Chin-Chen Chang

2. Outline Introduction VQ Related works The proposed scheme
SMVQ and CSMVQ
The proposed scheme
Experimental results
Conclusions

3. Introduction Secret data: 011 Receiver Reconstructed Image
Compression code …
Sender
Compression Code: …
Host Image
Secret data: 011

4. Introduction – Vector Quantization (VQ)

5. Related works – SMVQ (1/3)

6. Related works – SMVQ (2/3)

7. Related works – CSMVQ (3/3)
Variable-rate SMVQ with a Block Classifier

8. The proposed scheme (1/11)
Luminance-sorted Algorithm
Red pixel value
Blue pixel value
Luminance value
Green pixel value

9. The proposed scheme (2/11)
Luminance-sorted Algorithm

10. The proposed scheme (3/11)

11. The proposed scheme (4/11)

12. The proposed scheme (5/11)

13. The proposed scheme (6/11)
Assume that the
secret data is
001
If Distortion (K0, Original Pixel) < threshold T
Output: 1  indicator
100  compression code 4
Phase-1 data embedding K
Else if Distortion (K0, Original Pixel)
> threshold T
Use sorted color palette to embed secret data (Phase-2 data embedding)

14. The proposed scheme (7/11)
Phase-2 data embedding P
Best codeword
If D(Pc', P12) < D(Pc', P7)
Secret data: 0
Indicator: 0
0111
Secret data: 1
1100 P
Else if D(Pc', P12) > D(Pc', P7)
Secret data: 0
Indicator: 0
0000
Secret data: 1
1100

15. The proposed scheme (8/11)
Extracting Procedure

16. The proposed scheme (9/11)
Phase-1 extracting policy  indicator = 1
Ex: the inputted compression code is ‘100’
4 < 3
Decode with K0
The retrieval Secret data is 001 K

17. The proposed scheme (10/11)
Phase-2 extracting policy  indicator = 0
Ex: the inputted compression code is ‘0000’
Secret data is 0 P
Input next compression code 1100  12
Decode this pixel with P12

18. The proposed scheme (11/11)
Phase-2 extracting policy  indicator = 0
Ex: the inputted compression code is ‘0111’ P
7<12  Secret data is 0
If D(Pc', P12) < D(Pc', P7)
Decode the pixel with P12
Else
Decode the pixel with P7

19. Experimental results (1/4)
The color host images with size 512 × 512
Lena
Pepper
Baboon
Three stego-images for threshold T=20
PSNR: dB
Hiding capacity: 304 Kb
PSNR: dB
PSNR: dB
Hiding capacity: 271Kb
Hiding capacity: 257 Kb

20. Experimental results (2/4)

21. Experimental results (3/4)

22. Conclusions
A novel scheme is proposed to hide large amount of secret data into a color image.
The qualities of the reconstructed images are good.

23. Thank you so much!