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
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