Cryptography Reference
In-Depth Information
Scheme 2 [7] Both the secret palette and the shares palette are f;
Y
;
M
;
C
;
R
;
G
;
B
;g.
The base matrices are:
YMC
YMC
Y
MC
Y
MC
S
=
S
Y
=
M
CY
M
CY
C
YM
C
YM
S
M
=
S
C
=
YMC
MY
C
CYM
YC
M
S
R
=
S
G
=
MCY
CM
Y
YMC
YMC
S
=
S
B
=
For this scheme the pixel expansion is m = 8 and we have h = 1, ` = 0.
The annihilator presence is = 7=8 because in most cases 6 out of 8 pixels are
annihilated and for the color white 7 out of 8 pixels are annihilated. Because
of this, if we restrict the secret palette to if
Y
;
M
;
C
;
R
;
G
;
B
;g and add for the
shares palette the resulting scheme has h = 2 improving the contrast.
Scheme 3 [7]
Both
the
secret
palette
and
the
shares
color
palette
are
f;
Y
;
M
;
C
;
R
;
G
;
B
;g. The base matrices are:
YMC
BGR
YMC
GRB
S
=
S
Y
=
MCY
RBG
CYM
BGR
S
M
=
S
C
=
YMC
RBG
CYM
GRB
S
R
=
S
G
=
MCY
BGR
YMC
BGR
S
B
=
S
=
It is easy to see that for this scheme the pixel expansion is m = 5 and we
have h = 1, ` = 0. The annihilator presence = 4=5 because 4 out of 5 pixels
are annihilated.
Scheme 4 [1] The secret and shares palette are f
R
;
G
;
B
;
C
;
M
;
Y
g. The base ma-
trices are:
YMC
MY
C
YCM
CY
M
MCY
CM
Y
S
R
=
S
G
=
S
B
=
C
MY
C
MY
M
YC
M
YC
Y
CM
Y
CM
S
C
=
S
M
=
S
Y
=
It is easy to see that for this scheme the pixel expansion is m = 6 and we
have h = 2, ` = 0. The annihilator presence = 2=3 because 4 out of 6 pixels
are annihilated.
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