Received 29 December 2004; received in revised form 24
January 2006; accepted 3 February 2006
Authors : Chin-Chen Chang , Chih-Yang Lin , Yu-Zheng Wang
Adviser :Chih-Hung Lin
Reporter :Chien-Wen Huang
Date :2009.10 .24
1
1.
2.
3.
Introduction
Related Work
The Proposed Methods
 Hiding bitmap files
 Hiding general data files
4.
5.
Experimental Results
Discussion and Conclusions
2
 The
most well-known steganographic
technique-LSB.
 RLE
(Run-Length Encoding)
Compression standard in fax transmissions
and bitmap-file coding.
 Two
efficient data hiding methods by
run-length encoding .
BRL and GRL
3

Wu and Tsai’s steganographic method
4

Chang and Tseng’s steganographic method
5

RLE
Example1 :
AAAAABBBBAA
Example2:
111000001111
5A4B2A
315041
6

The host image is partitioned into non-overlapping
consecutive two-pixel blocks by zigzag scanning.
7

Hiding bitmap files
BRL hides the run value in vi and the run count
in ci .
The range that the remainder of ci modulo k falls
in – namely from 0 to (k-1)
Thus,the definition of sign is as follows:
8
The hiding process of BRL is formulated as follows:
The extraction scheme is as follows:
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Example:k=5, hiding secret bits:111000001111
111000001111
315041
RLE
(3,1)
(5,0)
(4,1)
(V1, C1) = (12, 8), (V2, C2) = (2, 3), (V3, C3) = (240, 254).
[LSB match]
'
c
1. 8 -> 3
1=8+x mod k = 3-1 x=-1 or 4
[LSB replace]
'
v1 =12+1=13
2. 12-> 1
 (v1' , c1' )  (13,7), (v2' , c2' )  (2,4), (v3' , c3' )  (241,253).
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
Hiding general data files
In GRL, the value of vi is the number of 1’s in C Ni (i ) ,
and the value of ci is the sequential order of
combinations by S n .
 The following mapping function f, where C Ni (i )
is set to be zero if n is smaller than k :
11

the value of
k can be obtained from v

'
The recursive function v i
'
i using
:
12
Example:
Six secret bits (101001) 2 are to be embedded in
the pair of original pixels (43, 58).
1. (101001) 2  three 1' s  k  3(共C3 種組合 )
2. k  vi' mod (n  1)  3  vi' mod 7  vi'  45
3. N(1)=1,N(2)=1,N(3)=2,N(4)=2,N(5)=3
6
f (101001)  i 1 bi C Ni ( i )  0  C11  0  C12
6 1
 1 C23  0  C24  1 C35  13
4. Ci' mod C36  13  Ci'  13,33,53  Ci'  53
13
The extraction process of (45,53) and n=6
'
v
1. i  45, n  6  k  3(i.e45 mod 7)
2. ci  53  num  13(53 mod C3 )
3. S5S4S3S2S1S0
s0:s5 s5=C(5,3)=10<13’1’ num=13-10=3
'
6
s0:s4 s4=C(4,2)=6>3’0’
s0:s3 s3=C(3,2)=3≦3’1’ num = 3-3 = 0
s0:s2 s2=‘0’ ;
s0:s1 s1=‘0’, s0=‘1’
14
15
16

Comparison of PSNR and capacities using
Lena as the cover image.
17

Comparison of PSNR and capacities using
Baboon as the cover image.
18


No need to refer to the original image during
the extraction process.
Probably be extended to embedding secret
data in compressed images using VQ or JPEG
techniques.
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