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r
it
y
,
a
w
ater
m
ar
k
i
s
s
cr
am
b
led
b
y
A
r
n
o
ld
tr
an
s
f
o
r
m
b
ef
o
r
e
w
ater
m
ar
k
e
m
b
ed
d
in
g
.
E
m
b
ed
d
in
g
r
eg
io
n
s
ar
e
d
eter
m
i
n
ed
b
ased
o
n
th
e
h
u
m
a
n
v
is
u
al
ch
ar
ac
ter
i
s
tic
en
tr
o
p
y
b
y
m
ea
s
u
r
i
n
g
t
h
e
e
n
tr
o
p
y
an
d
ed
g
e
e
n
tr
o
p
y
o
f
i
m
a
g
e
p
ix
els.
Selecte
d
b
lo
ck
s
b
ased
o
n
th
e
h
u
m
an
v
is
u
al
ch
ar
ac
ter
is
t
ic
en
tr
o
p
y
ar
e
tr
an
s
f
o
r
m
ed
u
s
i
n
g
T
ch
eb
ich
ef
m
o
m
e
n
t
tr
a
n
s
f
o
r
m
(
T
M
T
)
.
T
M
T
is
an
alter
n
a
tiv
e
s
o
lu
tio
n
to
i
m
p
r
o
v
e
D
C
T
p
er
f
o
r
m
an
ce
in
i
m
a
g
e
w
ater
m
ar
k
i
n
g
w
it
h
lo
w
co
m
p
u
tatio
n
a
l
co
s
t
u
s
in
g
m
atr
ices.
T
h
is
p
ap
er
also
r
ev
ea
ls
a
n
o
p
t
i
m
al
t
h
r
es
h
o
ld
as
a
tr
ad
e
-
o
f
f
b
et
w
ee
n
i
m
p
er
ce
p
tib
ilit
y
a
n
d
r
o
b
u
s
t
n
es
s
.
A
n
o
p
ti
m
al
th
r
es
h
o
ld
is
o
b
tain
ed
b
y
m
e
asu
r
i
n
g
SS
I
M
a
n
d
NC
v
al
u
es
a
g
ai
n
s
t
J
P
E
G
co
m
p
r
ess
io
n
.
J
P
E
G
co
m
p
r
ess
io
n
i
s
e
m
p
lo
y
ed
f
o
r
f
i
n
d
in
g
a
n
o
p
t
i
m
ized
t
h
r
es
h
o
ld
o
f
T
ch
eb
ich
ef
w
ater
m
ar
k
ed
i
m
a
g
es.
Ou
r
s
ch
e
m
e
is
d
esi
g
n
ed
to
ac
h
iev
e
h
i
g
h
r
o
b
u
s
t
n
es
s
an
d
m
i
n
i
m
u
m
d
is
to
r
tio
n
o
f
th
e
w
ater
m
ar
k
ed
i
m
ag
e.
2.
P
RE
L
I
M
I
NARIE
S
2
.
1
.
YCo
Cg
-
R
co
lo
r
s
pa
ce
Mo
s
t
o
f
w
a
ter
m
ar
k
in
g
s
c
h
e
m
es
ar
e
p
er
f
o
r
m
ed
u
s
in
g
YUV,
R
GB
[
6
]
,
an
d
YC
b
C
r
co
lo
r
s
p
ac
es
[
7
]
.
YC
b
C
r
h
as
b
ee
n
w
id
el
y
u
s
e
d
in
i
m
ag
e
co
m
p
r
es
s
io
n
[
8
]
-
[
1
1
]
,
th
is
co
lo
r
s
p
ac
e
is
ab
le
to
ac
h
iev
e
a
g
o
o
d
d
ec
o
r
elatio
n
o
f
th
e
co
lo
r
i
m
a
g
e.
Selectin
g
co
lo
r
s
p
ac
e
in
d
ig
ital
w
ater
m
ar
k
in
g
i
s
an
i
m
p
o
r
tan
t
ele
m
en
t
w
h
e
n
w
e
i
m
p
le
m
e
n
ted
o
n
t
h
e
co
lo
r
i
m
a
g
e.
T
h
i
s
r
esear
c
h
p
r
o
p
o
s
es
Y
C
o
C
g
-
R
to
o
b
tain
e
d
ec
o
r
r
elatio
n
co
lo
r
s
.
T
h
e
co
n
v
er
tio
n
f
r
o
m
R
GB
to
YC
o
C
g
-
R
ca
n
b
e
d
ef
i
n
ed
as:
)
2
/
(
)
2
/
(
Cg
t
Y
t
G
Cg
Co
B
t
B
R
Co
(
1
)
T
h
e
in
v
er
s
e
o
f
Y
C
o
Yg
-
R
co
lo
r
s
p
ac
e
is
d
ef
in
ed
as
Co
B
R
Co
t
B
t
Cg
G
Cg
Y
t
)
2
/
(
)
2
/
(
(
2
)
T
h
e
YC
o
C
g
co
lo
r
s
p
ac
e
co
n
s
i
s
t
o
f
t
h
r
ee
co
m
p
o
n
en
ts
L
u
m
in
a
n
ce
(
Y)
,
C
h
r
o
m
i
n
an
c
e
o
r
an
g
e
(
C
o
)
a
n
d
C
h
r
o
m
in
a
n
ce
g
r
ee
n
(
C
g
)
.
I
n
[
1
2
]
,
th
e
YC
o
Yg
-
R
co
lo
r
s
p
ac
e
h
as
b
ee
n
ap
p
lied
to
m
ai
n
tai
n
th
e
i
m
a
g
e
q
u
alit
y
an
d
r
ev
er
s
ib
ilit
y
o
f
i
m
a
g
e
w
at
er
m
ar
k
i
n
g
.
2
.
2
.
Arno
ld t
ra
ns
f
o
rm
A
w
ater
m
ar
k
i
m
a
g
e
i
s
s
cr
a
m
b
led
b
y
A
r
n
o
ld
tr
an
s
f
o
r
m
b
er
f
o
r
e
e
m
b
ed
d
in
g
w
ater
m
ar
k
.
A
r
n
o
ld
tr
an
s
f
o
r
m
ch
a
n
g
es
r
an
d
o
m
l
y
t
h
e
p
ix
el
p
o
s
itio
n
o
f
a
n
i
m
a
g
e
u
s
i
n
g
m
o
d
u
lo
o
p
er
atio
n
[
1
3
]
.
A
r
n
o
ld
s
cr
a
m
b
lin
g
tr
an
s
f
o
r
m
atio
n
is
g
iv
e
n
b
y
:
N
y
x
y
x
m
o
d
2
1
1
1
'
'
(
3
)
w
h
er
e
'
'
y
x
r
ep
r
esen
ts
t
h
e
v
ec
to
r
p
o
s
itio
n
af
ter
s
h
i
f
ti
n
g
,
y
x
d
en
o
tes
th
e
o
r
ig
i
n
al
v
ec
to
r
p
o
s
itio
n
b
ef
o
r
e
s
h
i
f
ti
n
g
,
mo
d
r
ep
r
esen
ts
th
e
m
o
d
u
l
u
s
o
p
er
atio
n
an
d
N
d
en
o
tes
th
e
p
er
io
d
o
f
s
cr
am
b
li
n
g
.
I
n
th
is
p
ap
er
,
N
is
u
s
ed
a
s
a
k
e
y
f
o
r
e
m
b
ed
d
in
g
a
n
d
ex
tr
ac
tio
n
o
f
s
cr
am
b
led
w
ater
m
ar
k
i
m
ag
e.
T
h
e
i
n
v
er
s
e
A
r
n
o
ld
tr
an
s
f
o
r
m
atio
n
is
d
ef
i
n
ed
as:
Evaluation Warning : The document was created with Spire.PDF for Python.
I
SS
N
:
2
0
8
8
-
8708
I
n
t J
E
lec
&
C
o
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p
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g
,
Vo
l.
9
,
No
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3
,
J
u
n
e
201
9
:
1
8
5
0
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1
8
6
0
1852
N
y
x
y
x
m
o
d
'
'
1
1
1
2
(
4
)
2
.
3
.
T
chebichef
m
o
m
ent
T
h
is
s
ec
tio
n
d
is
c
u
s
s
es
a
b
r
ief
l
y
r
e
v
ie
w
o
f
T
ch
eb
ich
e
f
p
o
ly
n
o
m
ia
ls
a
n
d
m
o
m
e
n
t
s
.
T
ch
eb
ich
ef
m
o
m
e
n
t
s
ar
e
co
m
p
u
ted
u
s
in
g
a
s
et
o
f
o
r
th
o
g
o
n
al
p
o
l
y
n
o
m
ials
[
1
4
]
.
T
h
e
T
ch
eb
ich
ef
m
o
m
e
n
t
ca
n
b
e
d
ef
in
ed
b
y
:
)
,
(
)
(
)
,
(
)
,
(
)
(
1
0
1
0
2
0
N
n
y
t
y
x
f
M
m
x
t
T
n
M
x
N
y
r
m
mn
(
5
)
w
h
er
e
f
(
x
,
y
)
d
en
o
tes
i
m
a
g
e
p
ix
els,
M
,
N
r
ep
r
esen
t
r
o
w
a
n
d
co
lu
m
n
s
ize
a
n
d
m
,
n
=
0
,
1
,
2
,
.
.
.
,
N
-
1
.
T
h
e
s
et
{
t
n
(
x
)
}
r
ep
r
esen
ts
th
e
r
ec
u
r
s
iv
e
r
elatio
n
.
T
h
e
in
v
er
s
e
T
ch
eb
ich
ef
m
o
m
en
t
s
is
g
i
v
en
as
f
o
llo
w
s
:
1
0
1
0
2
0
)
,
(
)
(
)
,
(
)
(
)
,
(
~
M
m
N
n
r
n
mn
m
N
n
y
t
T
M
m
x
t
y
x
f
(
6
)
w
h
er
e
)
,
(
~
y
x
f
d
en
o
tes i
m
ag
e
r
ec
o
n
s
tr
u
ctio
n
.
T
h
e
k
er
n
e
l o
f
T
MT
ca
n
b
e
d
ef
in
ed
b
y
:
)
,
(
)
(
,
)
,
(
)
(
N
n
y
t
K
M
m
x
t
K
n
y
m
x
(
7
)
T
h
e
T
ch
eb
ich
ef
m
o
m
e
n
t
s
o
f
t
h
e
o
r
ig
i
n
al
i
m
ag
e
ca
n
b
e
co
m
p
u
ted
b
y
:
FK
K
T
T
(
8
)
w
h
er
e
F
is
o
r
ig
i
n
al
i
m
ag
e.
T
h
e
in
v
er
s
e
T
MT
ca
n
b
e
co
m
p
u
t
ed
b
y
:
T
K
T
K
G
(
9
)
w
h
er
e
G
is
r
ec
o
n
s
tr
u
cted
i
m
ag
e.
T
h
e
f
ir
s
t f
o
u
r
T
ch
eb
ich
e
f
p
o
l
y
n
o
m
ial
s
ar
e
g
i
v
en
i
n
Fi
g
u
r
e
1
.
Fig
u
r
e
1
.
Dis
cr
ete
tch
eb
ic
h
ef
p
o
ly
n
o
m
ia
ls
t
n
(
x
)
3.
P
RO
P
O
SE
D
SCH
E
M
E
T
h
is
s
ec
tio
n
d
is
c
u
s
s
es t
h
e
p
r
o
p
o
s
ed
em
b
ed
d
in
g
an
d
ex
tr
ac
ti
n
g
w
a
ter
m
ar
k
.
T
h
e
w
ater
m
ar
k
in
s
er
tio
n
an
d
ex
tr
ac
tio
n
s
tep
s
ar
e
d
is
cu
s
s
ed
in
S
ub
-
s
ec
tio
n
s
3
.
1
an
d
3
.
2
r
esp
ec
tiv
el
y
.
3
.
1
.
P
r
o
po
s
ed
e
m
bedd
i
ng
s
c
he
m
e
Ste
p
1
:
A
n
im
ag
e
is
s
p
li
te
d
in
t
o
8
×
8
b
l
o
ck
p
ix
els.
Evaluation Warning : The document was created with Spire.PDF for Python.
I
n
t J
E
lec
&
C
o
m
p
E
n
g
I
SS
N:
2088
-
8708
Tch
eb
ich
ef
I
ma
g
e
W
a
terma
r
ki
n
g
a
lo
n
g
th
e
E
d
g
e
u
s
in
g
YC
o
C
g
-
R
co
lo
r
s
p
a
ce
fo
r
…
(
F
erd
a
E
r
n
a
w
a
n
)
1853
Ste
p
2
:
T
h
e
b
in
a
r
y
w
ater
m
ar
k
is
s
c
r
am
b
le
d
u
s
in
g
A
r
n
o
l
d
t
r
an
s
f
o
r
m
.
Ste
p
3
:
E
ac
h
im
ag
e
b
l
o
ck
is
c
o
m
p
u
ted
b
y
h
u
m
an
v
is
u
al
ch
ar
a
cte
r
is
t
ics
en
t
r
o
p
y
:
n
i
p
i
n
i
i
i
E
i
p
p
p
H
V
S
1
1
1
2
e
x
p
)
(
l
o
g
(
1
0
)
i
p
d
en
o
tes
th
e
o
c
cu
r
r
en
c
e
p
r
o
b
a
b
il
ity
o
f
i
-
th
p
ix
el
w
ith
1
0
i
p
an
d
n
i
i
p
1
1
.
Fu
r
th
e
r
m
o
r
e
,
th
e
v
alu
es
o
b
t
ain
e
d
o
f
HV
S
en
tr
o
p
y
ar
e
s
o
r
t
e
d
in
asc
en
d
in
g
o
r
d
er
.
Sel
ec
t b
l
o
ck
s
th
at
h
av
e
th
e
lo
w
est
HVS
en
tr
o
p
y
v
alu
e
f
o
r
em
b
ed
d
in
g
w
ater
m
ar
k
.
T
h
e
h
u
m
an
v
is
u
al
ch
ar
ac
t
er
is
ti
c
en
tr
o
p
y
h
as
b
ee
n
u
s
ed
in
th
e
p
r
ev
i
o
u
s
ex
p
er
im
en
t
in
[
1
5
]
,
[
1
6
]
an
d
g
y
r
at
o
r
d
o
m
ain
[
1
7
]
.
T
h
is
m
eth
o
d
ca
n
i
m
p
r
o
v
e
th
e
im
p
er
c
ep
ti
b
ili
ty
o
f
th
e
w
ater
m
ar
k
e
d
im
ag
e.
Ste
p
4
:
T
M
T
is
a
p
p
lie
d
o
n
e
ac
h
s
ele
ct
ed
b
l
o
ck
.
Ste
p
5
:
Sel
ec
t
C
(0
,
1
)
,
C
(
1
,
0)
,
C
(
0,
2
)
an
d
C
(2
,
0)
c
o
o
r
d
in
ates
o
n
e
ac
h
s
ele
cte
d
b
l
o
ck
.
T
h
ese
lo
ca
tio
n
s
h
a
v
e
p
o
ten
t
ial
to
m
ai
n
tai
n
th
e
i
m
ag
e
q
u
al
it
y
a
n
d
a
g
o
o
d
r
o
b
u
s
tn
es
s
.
T
h
e
T
ch
eb
ich
ef
m
o
m
en
t
o
f
th
ese
lo
c
ati
o
n
s
a
r
e
ad
d
e
d
v
alu
e
w
ith
w
ater
m
ar
k
w
eig
h
t.
Q
W
T
i
Q
)
(
(
1
1
)
w
h
er
e
T
d
en
o
tes
b
y
a
n
o
p
ti
m
al
th
r
es
h
o
ld
,
i
f
t
h
e
s
cr
a
m
b
led
w
a
ter
m
ar
k
b
it
W
i
s
1
,
t
h
en
W
Q
=1
.
Oth
er
w
i
s
e,
W
Q
=
-
1
.
I
f
th
e
e
m
b
ed
d
ed
s
cr
am
b
led
w
ater
m
ar
k
b
it
W
is
1
,
th
en
t
h
e
m
o
m
en
t
i
s
ad
d
ed
b
y
Q.
Oth
er
w
i
s
e,
th
e
m
o
m
e
n
t is
s
u
b
t
r
ac
ted
b
y
Q.
Ste
p
6
:
Gen
e
r
ate
th
e
s
e
q
u
en
c
e
r
an
d
o
m
n
u
m
b
er
s
u
s
in
g
m
er
s
e
n
n
e
t
w
is
ter
w
ith
a
s
ec
r
et
k
ey
.
T
h
e
w
ater
m
ar
k
is
r
an
d
o
m
ly
em
b
ed
d
ed
in
th
e
l
o
c
ati
o
n
s
o
f
C
(
0,
1)
,
C
(1
,
0)
,
C
(0
,
2
)
an
d
C
(2,
0)
.
Ste
p
7
:
T
h
e
s
e
lec
te
d
b
lo
ck
s
a
r
e
c
o
m
p
u
ted
b
y
in
v
er
s
e
T
M
T
.
Ste
p
8
:
Gen
er
ate
th
e
w
ater
m
ar
k
ed
im
ag
e.
I
n
th
i
s
ex
p
er
i
m
e
n
t,
t
h
e
lo
ca
tio
n
o
f
e
m
b
ed
d
in
g
w
a
ter
m
ar
k
h
as
d
eter
m
i
n
ed
in
C
(0,
1)
,
C
(1
,
0
)
,
C
(0
,
2)
an
d
C
(2,
0)
o
f
th
e
m
atr
i
x
m
o
m
en
t
b
ased
o
n
T
M
T
.
T
h
ese
lo
ca
tio
n
s
h
av
e
s
ig
n
i
f
ica
n
tl
y
less
er
r
o
r
r
ec
o
n
s
tr
u
ctio
n
a
n
d
th
e
w
ater
m
ar
k
ed
i
m
ag
e
ca
n
ac
h
iev
e
h
i
g
h
i
m
p
er
ce
p
tib
ilit
y
u
s
in
g
YC
o
C
g
-
R
co
lo
r
s
p
ac
e.
Du
e
to
i
m
p
r
o
v
in
g
t
h
e
s
ec
u
r
it
y
lev
el,
w
e
u
s
e
A
r
n
o
ld
tr
an
s
f
o
r
m
to
s
cr
a
m
b
le
th
e
w
a
ter
m
ar
k
an
d
t
h
e
e
m
b
ed
d
in
g
wate
r
m
ar
k
lo
ca
tio
n
s
ar
e
r
an
d
o
m
ized
b
ased
o
n
a
s
ec
r
et
k
e
y
.
3
.
2
.
P
r
o
po
s
ed
ex
t
ra
ct
io
n sche
m
e
Step
1
:
W
e
u
s
e
x
an
d
y
co
o
r
d
in
ates
to
id
en
ti
f
y
t
h
e
e
m
b
ed
d
ed
r
eg
io
n
s
.
Div
id
e
th
e
s
e
lect
ed
r
eg
io
n
in
to
n
o
n
-
o
v
er
lap
p
in
g
b
lo
ck
o
f
8
×8
p
ix
e
ls
.
Step
2
: E
ac
h
s
elec
ted
b
lo
ck
is
tr
an
s
f
o
r
m
b
y
T
MT
.
Step
3
:
Gen
er
ate
th
e
r
an
d
o
m
n
u
m
b
er
s
u
s
i
n
g
t
h
e
s
a
m
e
s
ec
r
e
t
k
e
y
.
T
h
e
s
eq
u
en
ce
r
an
d
o
m
n
u
m
b
er
s
ar
e
u
s
ed
to
id
en
ti
f
y
e
x
tr
ac
ti
n
g
w
ater
m
ar
k
lo
ca
tio
n
o
f
C
(0,
1
)
,
C
(1
,
0
)
,
C
(
0,
2)
a
n
d
C
(
2,
0)
.
Step
4
: Co
m
p
u
te
t
h
e
co
r
r
elatio
n
co
ef
f
icie
n
ts
:
(
12
)
w
h
er
e
X
r
ep
r
esen
t
s
t
h
e
w
ater
m
ar
k
ed
i
m
a
g
e
a
n
d
X
*
d
en
o
tes
th
e
s
eq
u
en
ce
o
f
w
ater
m
ar
k
e
x
t
r
ac
tio
n
.
T
h
e
w
ater
m
ar
k
b
it i
s
1
,
if
th
e
co
r
r
elatio
n
r
esu
lt is
g
r
ea
ter
th
a
n
a
th
r
es
h
o
ld
.
o
th
er
w
i
s
e,
th
e
v
is
e
v
er
s
a.
Step
5
:
I
n
v
er
s
e
A
r
n
o
ld
t
r
an
s
f
o
r
m
to
r
esto
r
e
th
e
w
a
ter
m
ar
k
b
in
ar
y
i
m
a
g
e.
Step
6
:
Gen
er
ate
th
e
w
ater
m
ar
k
r
ec
o
v
er
y
.
3
.
3
.
An o
ptim
a
l t
hre
s
ho
ld
I
n
o
r
d
er
to
in
v
est
ig
ate
t
h
e
tr
a
d
e
-
o
f
f
b
et
w
ee
n
r
o
b
u
s
t
n
e
s
s
a
n
d
in
v
is
ib
ili
t
y
,
th
e
w
ater
m
ar
k
e
d
i
m
a
g
e
i
s
co
m
p
r
es
s
ed
b
y
J
P
E
G
co
m
p
r
ess
io
n
.
W
e
in
cr
ea
s
e
th
e
t
h
r
es
h
o
ld
b
y
o
n
e
at
a
tim
e
f
o
r
e
m
b
ed
d
in
g
w
ater
m
ar
k
,
th
u
s
w
e
ap
p
l
y
J
P
E
G
co
m
p
r
e
s
s
io
n
.
T
h
e
i
n
v
is
ib
ili
t
y
o
f
w
a
ter
m
ar
k
ed
i
m
a
g
e
is
a
s
s
e
s
s
ed
b
y
SS
I
M
a
n
d
t
h
e
r
esis
ta
n
t
o
f
e
x
tr
ac
ted
w
ater
m
ar
k
a
f
ter
d
i
f
f
er
e
n
t
attac
k
s
is
m
ea
s
u
r
ed
b
y
NC
.
T
h
e
r
e
latio
n
s
h
ip
b
et
w
ee
n
i
m
p
er
ce
p
tib
ilit
y
a
n
d
r
o
b
u
s
tn
e
s
s
f
r
o
m
J
P
E
G
co
m
p
r
es
s
io
n
i
s
s
h
o
w
n
in
F
ig
u
r
e
2
(
a)
L
ai’
s
s
ch
e
m
e
[
5
]
an
d
Fig
u
r
e
2
(
b
)
p
r
o
p
o
s
ed
s
ch
e
m
e.
X
X
Evaluation Warning : The document was created with Spire.PDF for Python.
I
SS
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:
2
0
8
8
-
8708
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n
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&
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p
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n
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l.
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,
No
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J
u
n
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201
9
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8
5
0
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1
8
6
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(
a
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ai’
s
s
ch
e
m
e
(
b
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r
o
p
o
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ed
s
ch
e
m
e
Fig
u
r
e
2
.
T
h
e
o
p
tim
a
l th
r
es
h
o
l
d
f
o
r
(
a)
L
ai’
s
s
c
h
e
m
e,
(
b
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th
e
p
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o
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ed
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ch
e
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e
R
ef
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r
i
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to
Fig
u
r
e
2
,
th
e
e
x
p
er
i
m
en
tal
r
es
u
lts
s
h
o
w
th
at
th
e
o
p
ti
m
al
v
a
lu
e
ca
n
b
e
ac
h
iev
e
d
u
s
i
n
g
th
e
tr
ad
eo
f
f
b
et
w
ee
n
r
esi
s
ta
n
t
a
n
d
in
v
is
ib
le
o
f
w
a
ter
m
ar
k
ed
i
m
ag
e
ag
a
in
s
t
J
P
E
G
co
m
p
r
es
s
io
n
.
T
h
e
p
r
o
p
o
s
ed
w
ater
m
ar
k
i
n
g
s
ch
e
m
e
ca
n
ac
h
iev
e
t
h
e
tr
ad
eo
f
f
b
et
w
ee
n
in
v
i
s
ib
ilit
y
a
n
d
r
e
s
is
ta
n
t
w
it
h
t
h
e
s
ca
le
f
ac
to
r
o
f
8
f
o
r
th
e
w
eig
h
ted
w
a
ter
m
ar
k
ed
i
m
ag
es.
Ho
w
e
v
er
,
th
e
o
p
ti
m
al
t
h
r
esh
o
ld
o
f
L
ai
’
s
s
c
h
e
m
e
i
s
0
.
0
1
6
as
p
r
esen
ted
in
Fig
u
r
e
2
(
a)
.
4.
E
VA
L
UA
T
I
O
NS
T
h
is
s
ec
tio
n
d
escr
ib
es
t
h
e
e
v
alu
a
tio
n
o
f
th
e
p
r
o
p
o
s
ed
w
ater
m
ar
k
i
n
g
s
c
h
e
m
e
to
d
e
m
o
n
s
tr
ate
t
h
e
w
ater
m
ar
k
i
n
g
p
er
f
o
r
m
a
n
ce
ag
ain
s
t
d
if
f
er
en
t
t
y
p
es
o
f
attac
k
.
T
h
e
p
r
o
p
o
s
ed
w
ater
m
ar
k
i
n
g
s
ch
e
m
e
i
s
test
ed
in
to
ei
g
h
t
co
lo
r
i
m
ag
e
s
w
it
h
5
1
2
×5
1
2
p
ix
els
as
s
h
o
w
n
in
Fig
u
r
e
3
.
E
ig
h
t
i
m
ag
e
s
ar
e
s
elec
ted
to
test
th
e
p
r
o
p
o
s
ed
alg
o
r
ith
m
n
a
m
ed
a
s
:
“L
e
n
a”
,
“
P
ep
p
er
”,
“
C
ar
”,
“A
ir
p
lan
e”
,
“L
ak
e”
,
“
T
if
f
a
n
y
”,
“
B
ab
o
o
n
”
an
d
“
Sai
lb
o
at”
.
T
h
e
b
in
ar
y
w
ater
m
ar
k
w
ith
s
ize
o
f
3
2
×3
2
p
ix
els is
s
h
o
w
n
i
n
Fi
g
u
r
e
4
.
(
a)
(
b
)
(
c)
(
d
)
(
e)
(
f
)
(
g
)
(
h
)
Fig
u
r
e
3
.
Ho
s
t i
m
a
g
es: (
a)
L
e
n
a,
(
b
)
P
ep
p
er
,
(
c
)
C
ar
,
(
d
)
A
ir
p
lan
e,
(
e)
L
ak
e,
(
f
)
T
if
f
an
y
,
(
g
)
B
ab
o
o
n
an
d
(
h
)
Sailb
o
at
Evaluation Warning : The document was created with Spire.PDF for Python.
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&
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Tch
eb
ich
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I
ma
g
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W
a
terma
r
ki
n
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a
lo
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e
E
d
g
e
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g
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r
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a
ce
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r
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(
F
erd
a
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r
n
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w
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n
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1855
Fig
u
r
e
4
.
W
ater
m
ar
k
i
m
a
g
e
4
.
1
.
I
m
perc
ept
ib
ility
ev
a
lua
t
io
n
T
h
e
im
p
er
ce
p
tib
ilit
y
o
f
w
ate
r
m
ar
k
ed
i
m
a
g
e
is
esti
m
ated
b
y
Str
u
ct
u
r
al
SIM
ilar
it
y
(
SS
I
M)
in
d
ex
.
SS
I
M
is
d
ef
i
n
ed
b
y
[
1
8
]
:
12
2
2
2
2
12
(
2
)
(
2
c
)
(
x
,
y
)
(
)
(
c
)
xy
xy
x
y
c
S
S
I
M
x
y
c
(
1
3
)
w
h
er
e
x
an
d
y
r
ep
r
ese
n
t
t
h
e
i
m
ag
e
p
ix
el
co
o
r
d
in
ates
o
f
t
h
e
o
r
ig
in
al
a
n
d
w
ater
m
ar
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ed
i
m
ag
es,
r
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el
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w
o
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n
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ta
n
t
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2
11
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k
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e
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ilize
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e
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iv
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n
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it
h
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en
o
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i
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h
er
e
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e
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y
n
a
m
ic
r
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g
e
o
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p
ix
e
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w
h
ic
h
is
2
5
5
f
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).
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NC
E
S
[1
]
F
.
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a
term
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teristics
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trate
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9
th
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ter
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No
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.
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