Signal Analysis Research (SAR) Group - RNet - Ryerson University
Signal Analysis Research (SAR) Group - RNet - Ryerson University
Signal Analysis Research (SAR) Group - RNet - Ryerson University
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ing a large number of cells in Hough-Radon space shifts<br />
the peak of the accumulator to the neighbor cells and consequently<br />
results in a wrong detection of the slope in TFD.<br />
Therefore, we see in Figure 3 that DPPT-based method outperforms<br />
HRT-based algorithm in most of the attack types<br />
with a total detection of 92% compared to 87%. Also, comparing<br />
the complexity order of HRT-based and DPPT-based<br />
techniques, we conclude that the DPPT-based method is<br />
more practical for real-time applications. Figure 4, shows<br />
the complexity order and running time based on Pentium<br />
IV, CPU 2.66GHz and 512MB of RAM. DPPT-based watermark<br />
extraction is about 55 times faster than HRT-based<br />
algorithm.<br />
As we observe in Figure 3, the detection result for the<br />
BCH coding and repetition codings have almost the same<br />
detection rates, but DPPT-based method offers better or in<br />
some cases equal results when compared to REP and BCH<br />
codings. Figure 5 shows the detection results considering<br />
BER in the received message. As we see in this figure, both<br />
DPPT and BCH detect 100% watermark messages successfully<br />
up to a BER of 17%. However, the maximum BER<br />
that BCH detects a watermark correctly is 22% with 17%<br />
detection, while DPPT shows 50% detection rate at a BER<br />
of 28%. To highlight the outstanding performance of DPPT<br />
at high BERs, we calculate the watermark detection rate<br />
for BERs bigger than 17%. We see that the DPPT-based<br />
method offers 52% detection rate in higher BERs, while<br />
BCH and Repetition codings have 47% and 41% detection<br />
rates.<br />
Figure 4. Order of complexity of each coding<br />
schemes used to code the watermark message<br />
5. Conclusions<br />
In this paper, we compared FEC-based and chirp-based<br />
post processing methods in watermarking. The robustness<br />
of the proposed techniques was tested against checkmark<br />
benchmark attacks. The DPPT-based and BCH-based methods<br />
were able to compensate the BER of up to 17%. The<br />
DPPT-based post processing offered the highest detection<br />
rate of 92%, and showed the highest detection rate for BERs<br />
of higher than 17%. Also, we compared the computation<br />
complexity of the proposed methods; BCH, repetition<br />
and DPPT-based methods have almost the same complex-<br />
Proceedings of the 2006 International Conference on Intelligent<br />
Information Hiding and Multimedia <strong>Signal</strong> Processing (IIH-MSP'06)<br />
0-7695-2745-0/06 $20.00 © 2006<br />
Successful watermark estimation(%)<br />
100<br />
90<br />
80<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
HRT<br />
REP<br />
BCH<br />
DPT<br />
0<br />
0 5 10 15 20 25 30 35 40<br />
BER of the received watermark message<br />
Figure 5. Watermark detection under different<br />
bit error rates.<br />
ity, while HRT has a complexity of 55 times higher than the<br />
other methods, and this is because HRT operates on the TF<br />
plane, and calculates the accumulator value for all the cells<br />
in Hough-Radon plane.<br />
References<br />
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