1. 2003/04/291 Hiding data in images by optimal moderately- significant-bit replacement Wang, Ran-Zan, Lin, Chi-Fang, and Lin, Ja-Chen, IEE Electronics Letters, VOL. 36, NO. 25, 7th December 2000, pp. 2069-2070 Adviser : Dr. Chang, Chin-Chen Reporter : Chi, Kang-Liang Date : 2003/04/29

2. 2003/04/292 Outline Introduction Proposed data hiding scheme Experimental results Conclusions

3. 2003/04/293 Introduction

4. 2003/04/294 Proposed data hiding scheme 0010 1110 0110 1001 1029315 162243100 79213176162 2793121200 important imagehost image

5. 2003/04/295 Proposed data hiding scheme Definition : Pixel at location of important image is transposed to a new location by the following equation : mod where, for and are constants.

6. 2003/04/296 Proposed data hiding scheme Let mod where gcd(5,16)=1, gcd(3,16)=1, and gcd(5,3)=1 0123 4567 891011 12131415 94 10 50116 11272 138314 The location of important image The location of perturbed image

7. 2003/04/297 Proposed data hiding scheme 1111 1001 0101 0000 perturbed image

8. 2003/04/298 Proposed data hiding scheme 10=00001010 29=00011101 MSB(the fifth bit) 1110 0010 1000 1111 residual image

9. 2003/04/299 Proposed data hiding scheme Both the perturbed image and the residual image are divided into non-overlapping blocks of size 4*1. perturbed image ={1111,1001,0101,0000)} residual image ={1110,0010,1000,1111}

10. 2003/04/2910 Proposed data hiding scheme Genetic algorithm (GA) Given a chromosome G={0000,0001, …,1111}, two of the 16 genes of G are selected randomly and replaced by each other. Assume we get the best replacement : {1111}  {1100}, {1001}  {0001} {0101}  {1101}, {0000}  {1111}

11. 2003/04/2911 Proposed data hiding scheme 1100 0001 1101 1111 1029235 162235108 79221176170 2793121200 temporal imageoptimal substitution image 00010111=23

12. 2003/04/2912 Proposed data hiding scheme 23=31-8 and 7 4 then 8-7-1 is added to 23. 35=43-8, 3<4, and the fourth bit of 35 is 0, then the fourth bit of 35 is changed to 1, and 51-3=48.

13. 2003/04/2913 Proposed data hiding scheme 108=100+8, 4 4, and the fourth bit of 108 is not equal to 1, do nothing. 221=213+8, 5 4, and the fourth bit of 221 is equal to 1, then the fourth bit of 221 is changed to 0, and the value is add 8-5-1 is added to 205. 170=162+8, 2<4,then 170-2=168.

14. 2003/04/2914 Proposed data hiding scheme 1029235 162248108 79207176168 2793121200 resulting image

15. 2003/04/2915 Experimental results host image important image simple replacement method ( 33.02 dB ) proposed method ( 38.75 dB )

16. 2003/04/2916 Conclusions With careful design, such as the use of optimal substitution process and local pixel adjustment, MSB can still be used as an alternative choice for the storage and transmission of important data. Improved methods 1. Chan, Chi-Kwong, and Cheng, L.M., “ Improved hiding data in images by optimal moderately- significant-bit replacement ”, IEE Electronic Letters, Vol.37, No.16, 2nd August 2001, pp.1017-1018

17. 2003/04/2917 Conclusions 2. Chang, Chin-Chen, Hu, Yu-Chen, and Lin, Min- Hui, ” A Fast and Secure Image Hiding Scheme Based on LSB Substitution ”,International Journal of Pattern Recognition and Artificial Intelligence, Vol.16, No.4, 2002, pp.399-416