1. 1 Adaptive Data Hiding in Palette images by Color Ordering and Mapping With Security Protection Authors: Chih-Hsuan Tzeng, Zhi-Fang Yang, and Wen-Hsiang Tsai Source: IEEE Transactions On Communications, Vol. 52, No. 5, May 2004, pp. 791-800. Adviser ： Wen-Chung Kuo Jiin -Chiou Cheng Repoter ： Wei-De Hsu

2. 2 Outline Introduction The proposed method –Color-ordering relationship –Color-mapping function –Data-embedding process –Data-extraction process Experimental results Conclusions

3. 3 Introduction Gifshuffle –The idea is to permute the colors in the palette of an image in a specific order in accordance with the secret data. (256!) indexescolors 00 0 0 10 255 0 2255 0 0 30 0 255 Ex: 4! [6] M. Kwan. (1998) GIF Colormap Steganography. [Online]. Available: http://www.darkside.com.au/gifshuffle/

4. 4 Introduction (a) The original image. (b) Replacement by the closet color. (c) Replacement by the neighboring color. Three colors c 1, c 2, c 3, with RGB values (0, 174, 239), (57, 181, 74), and (236, 0, 140) are contained in the sample images. [12] J. Fridrich and R. Du, “Secure steganographic methods for palette images,” in Proc. 3 rd Int. Workshop Information Hiding, Dresden, Germany, 1999, pp. 47–60.

5. 5 Color-ordering relationship c1c1 c2c2 c3c3 c4c4

6. 6 Proposed data-embedding process 12 16 10 12 60 121617 1018

7. 7 Proposed data-embedding process 12 60 Non-embeddable

8. 8 Proposed data-embedding process 12 16 10 121617 1060 embeddable

9. 9 Color-mapping function c1c1 c2c2 c3c3 c4c4

10. 10 Color-mapping function Hiding 0Hiding 1

11. 11 Data-extraction process

12. 12 Experimental results 15640 bits/44.8dB

13. 13 Experimental results 2003 bits/43.7dB

14. 14 Experimental results

15. 15 Conclusions The experimental results show that secret data can be embedded and extracted successfully without producing visual artifacts in the cover image. A good balance between stego-image quality and data-embedding capacity can be achieved.