Cryptography Reference
In-Depth Information
1-bit-WM Scheme
WM embedding
=y
(f )
i
The luminance set of the f -th frame consisting of N pixels is y
(f )
1≤i≤N. The process flow of the 1-bit-WM embedding is as follows.
Step E1: Do the following steps over f =1, 2,.
Step E2: Use the original frame y
(f )
and divide y
(f )
into R regions y
(f,r)
s
=1,,R) consisting of the corresponding pixels: y
(f,r)
(r
=
, which satisfies y
(f )
y
(f,r)
i
N
R
r
y
(f,r)
, y
(f,r)
1≤i≤
=
r=r
′
y
(f,r
′
)
=∅.
Step E3: Generate each watermarked region y
′
(f,r)
by adding the WM pat-
N
R
tern m =
. This comprised of a
pseudo random array1s and added to the original region y
m
i
∈−1, +11≤i≤
′
(f,r)
:
y
(f,r)
+ µ
(f,r)
m,
if b =1,
′
(f,r)
y
=
(7.10)
y
(f,r)
−µ
(f,r)
m,
if b =0,
where µ
(f,r)
is WM strength of the region y
(f,r)
.
Step E4: Output the watermarked frame y
′
(f )
.
WM detection
The correlation value c is calculated by correlating the WM pattern m with
the accumulated region.
Step D1: Do the following steps over f
0
=1,F +1, 2F +1,.
Step D2: Input F watermarked frames y
′
(f )
s(f = f
0
,,f
0
+ F−1) and
divide FR regions y
′
(f,r)
s(f = f
0
,,f
0
+ F−1,r =1,,R).
Step D3: Accumulate the FR regions y
′
(f,r)
s, in the region: y
= y
i
N
R
1≤i≤
. The y
i
of the accumulated region y is given by
f
0
+F−1
R
1
FR
′
(f,r)
i
y
i
=
y
.
(7.11)
f =f
0
r=1
Step D4: Calculate the correlation value c, which is obtained by correlating
the WM pattern m with the accumulated region y.Thatis,
⌊
R
⌋
1
1
FR
m
i
y
(f,r)
c =
m
i
y
i
=
µ,
(7.12)
i
N
R
N
R
i=1
f,r,i
f,r
µ
(f,r)
. Since m
i
y
(f,r)
1
FR
where µ is WM signal given by µ =
i
is considered to be an independent stochastic variable with mean
0 [13], each c follows the normal distribution with meanµ and