Hiding data in images by optimal moderatelysignificantbit replacement

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

Outline n n Introduction Proposed data hiding scheme Experimental results Conclusions 2003/04/29 2

Introduction 2003/04/29 3

Proposed data hiding scheme 0 1 0 0 1 1 1 0 0 0 10 16 79 29 31 5 22 43 100 213 176 162 1 0 0 1 27 93 important image 2003/04/29 121 200 host image 4

Proposed data hiding scheme Definition : Pixel at location of important image is transposed to a new location by the following equation : mod n where , 2003/04/29 for and are constants. 5

Proposed data hiding scheme Let mod where gcd(5, 16)=1, gcd(3, 16)=1, and gcd(5, 3)=1 0 4 8 12 1 5 9 13 2 6 10 14 3 7 11 15 The location of important image 2003/04/29 9 5 1 13 4 0 12 8 15 11 7 3 10 6 2 14 The location of perturbed image 6

Proposed data hiding scheme 1 1 1 0 0 1 0 1 0 0 perturbed image 2003/04/29 7

Proposed data hiding scheme MSB(the fifth bit) 10=00001010 29=00011101 1 0 0 0 1 1 residual image 2003/04/29 8

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)} n residual image ={1110, 0010, 1000, 1111} 2003/04/29 9

Proposed data hiding scheme n 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} {0101} {1101} , {0000} {1111} 2003/04/29 10

Proposed data hiding scheme 1 1 0 0 10 29 23 5 0 0 0 1 16 22 35 108 1 1 0 1 79 221 176 170 1 1 27 93 temporal image 121 200 optimal substitution image 00010111=23 2003/04/29 11

Proposed data hiding scheme n n 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. 2003/04/29 12

Proposed data hiding scheme n n n 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. 2003/04/29 13

Proposed data hiding scheme 10 29 23 5 16 22 48 108 79 207 176 168 27 93 121 200 resulting image 2003/04/29 14

Experimental results host image simple replacement method 2003/04/29 ( 33. 02 d. B ) important image proposed method ( 38. 75 d. B ) 15

Conclusions n n 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 moderatelysignificant-bit replacement”, IEE Electronic Letters, Vol. 37, No. 16, 2 nd August 2001, pp. 1017 -1018 2003/04/29 16

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 2003/04/29 17