Cryptography Reference
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(a) p
1
=0.0, p
2
=1.0, BCR
1
=81.03%, BCR
2
=68.23%
(b) p
1
=1.0, p
2
=0.0, BCR
1
=67.00%, BCR
2
=69.71%
Fig. 12.12.
The two extracted watermarks under the case when one channel is total
breakdown in Sec. 12.5.2, with a codebook size of L = 512.
algorithm, we can embed twice as much as the watermark capacity than those
given in [10] and [11]. Thus, while only one watermark can be extracted using
the existing algorithms, the corresponding BCR values using our algorithm
are better than those in [10] and [11].
Table 12.2.
Comparisons of the watermarked image quality under different chan-
nel erasure probabilities with a codebook length of L = 512 after considering the
embedding of the two watermarks in Sec. 12.5.1.
PSNR with our
PSNR with [10]
PSNR with [11]
Channel erasure probability
p
1
p
2
method (in dB)
(in dB)
(in dB)
0
0
30.74
30.46
30.64
0.1
0.1
28.15
28.14
28.56
0.25
0.25
24.39
24.37
24.40
0.5
0.5
19.88
19.93
19.86
0
1
26.19
25.92
25.41
1
0
26.13
26.04
25.48
In Fig. 12.13, similar comparisons can be made by following those given
in Fig. 12.11. Fig. 12.13(a) shows the extracted watermarks during error-
free transmission. These are identical to those embedded in Fig. 12.8. In
