Received 29 December 2004; received in revised form 24
January 2006; accepted 3 February 2006
Information Sciences, Vol. 176, No. 22, Nov. 2006, pp. 3393-3408
Reporter : Chien-Wen Huang
Date :2009.10 .24
1

1.
2.
3.
4.
5.
Introduction
Related Work
The Proposed Methods
 Hiding bitmap files
 Hiding general data files
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 5A4B2A
 Example2:
111000001111 315041
6


The host image is partitioned into non-overlapping consecutive two-pixel blocks by zigzag scanning.
7


Hiding bitmap files
 c v i
 in – namely from 0 to (k-1) c i
Thus,the definition of sign is as follows:
8

 The hiding process of BRL is formulated as follows:
 The extraction scheme is as follows:
9

 Example:k=5, hiding secret bits:111000001111
111000001111 315041
RLE
(3,1) (5,0) (4,1)
(V
1
, C
1
) = (12, 8), (V
2
, C
2
) = (2, 3), (V
3
, C
3
) = (240, 254).
[LSB match]
1.
[LSB replace]
2.
c v
'
12-> 1 =12+1=13

( v
1
'
, c
1
'
)

( 13 , 7 ), ( v
2
'
, c
2
'
)

( 2 , 4 ), ( v
3
'
, c
3
'
)

( 241 , 253 ).
10


Hiding general data files
 c
S n i v i and the value of is the sequential order of
C
N ( i )
 The following mapping function f, where
C is set to be zero if n is smaller than k :
N i
( i )
11


 k v v
12

 Example:
( 101001 ) the pair of original pixels (43, 58).
1.
2.
( 101001 k
 v
' i
)
2 mod

( n three

1 )
1'

3 s

 v
' i k
 mod
3 (
7
共

C v
' i
3
6

種組合
45
3.
N(1)=1,N(2)=1,N(3)=2,N(4)=2,N(5)=3
) f ( 101001 )
  i
6

1

1 b i
C
N i
( i )

0

C
1
1 
0

C
1
2

1

C
2
3 
0

C
2
4 
1

C
3
5 
13
4.
C i
' mod C
3
6 
13

C i
' 
13 , 33 , 53

C i
' 
53
13

 The extraction process of (45,53) and n=6
1.
2.
v i
' c
' i
3.
S
5 s
0
:s
5
 s

45 ,
53 n


6
 num k


3 ( i .
e
13 ( 53
45 mod mod C
7 )
6
)
S
4
S
3
S
2
S
1
3
S
0
5
=C(5,3)=10<13
 ’1’ num
=13-10=3 s
0
:s
4 s
4
=C(4,2)=6>3
 ’0’ s
0
: s
3 s
3
=C(3,2)=3 ≦ 3  ’1’ num = 3-3 = 0 s
0
:s
2 s
2
=‘0’ ; s
0
:s
1 s
1
=‘0’, s
0
=‘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.
19