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 Adviser : Dr. Chang, Chin-Chen Reporter : Chi, Kang-Liang Date : 2003/04/29

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

2003/04/293 Introduction

2003/04/294 Proposed data hiding scheme important imagehost image

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.

2003/04/296 Proposed data hiding scheme Let mod where gcd(5,16)=1, gcd(3,16)=1, and gcd(5,3)= The location of important image The location of perturbed image

2003/04/297 Proposed data hiding scheme perturbed image

2003/04/298 Proposed data hiding scheme 10= = MSB(the fifth bit) residual image

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}

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}

2003/04/2911 Proposed data hiding scheme temporal imageoptimal substitution image =23

2003/04/2912 Proposed data hiding scheme 23=31-8 and 7 4 then is added to =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.

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 is added to =162+8, 2<4,then 170-2=168.

2003/04/2914 Proposed data hiding scheme resulting image

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

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

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