Information Technology Reference
In-Depth Information
R
. Choosing a threshold
T
for detecting LSB steganography, the probability of missing
a secret-data carrying image,
P
m
, and the probability of false alarm,
P
f
, may be deter-
mined. In Table 1,
P
m
, and
P
f
under different
T
are given. Obviously, a large
T
results in
a small
P
f
and large
P
m
. When the payload is large enough and a suitable threshold
chosen, the two types of error become fairly small.
(a)
(b)
1.14
milkdrop
man
couple
1.12
1.1
1.08
1.06
1.04
1.02
1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Payload L
(c) (d)
Fig. 1.
Images Milkdrop (a), Man (b), Couple (c), and relation between
R
and payload (d)
Table 1.
Detection performance with different threshold
T
False alarm prob-
ability
P
f
(%)
Missing probability
P
m
(%)
T
L
=0.25
L
=0.50
L
=0.75
L
=1.0
1.010
11.69
5.97
1.04
0.52
0.26
1.015
5.45
10.39
3.38
1.56
0.52
1.020
2.86
19.48
4.68
2.08
0.52
1.025
1.82
29.61
8.31
4.16
1.82
1.030
1.04
43.38
12.21
5.97
2.86
