MASTER THESIS Video Watermarking - Computer Graphics Group ...
MASTER THESIS Video Watermarking - Computer Graphics Group ...
MASTER THESIS Video Watermarking - Computer Graphics Group ...
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
5.4.4 Denoising<br />
Denoising is an attack especially against noise watermarking method. It<br />
consists in removing noise from the video sequence which could cause noise<br />
watermark removal. MPlayer high quality denoise 3D filter (“hqdn3d”) is used<br />
with “spatial luma strength” set to 16 and other parameters set to 0.<br />
The test results are summarized in Table 7.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
Table 7: Denoising test results<br />
Despite the expectations, all the methods have gone well.<br />
5.4.5 Noising<br />
Noising is the opposite process to denoising, namely adding noise to the<br />
video sequence. MPlayer “noise” filter is used with parameters equal to “10t:0”,<br />
i.e. only luma samples are affected by Gaussian noise changing in time with<br />
amplitude of 10.<br />
No significant influence is expected in case of noise method because another<br />
noise does not interfere with the noise watermark. Lesser influence is expected in<br />
case of coefficient method because the method alters only one coefficient per<br />
macroblock. The coefficient is hardly impaired by noise due to quantization. The<br />
quantization effect is expected when using block method as well.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
Table 8: Noising test results<br />
The results in Table 8 are as expected. Moreover, the probability grows up in<br />
case of noise method with weight factor of 2 in comparison with results of the<br />
recompression at the former bit-rate test.<br />
44