Re: [WM]: low freq & Middle-High Freq. watermarking

["Jeffrey Bloom" <jbloom@sarnoff.com>]

Krutarth,

Assuming a correlation-based detector, the autocorrelation of a
low-frequency pattern will be quite wide.  Thus, there will be little
degradation of the correlation detection value based on slight geometric
misalignments.

One advantage of mid/high frequency patterns is that they live in a much
higher dimensional space.  One property of high dimensional spaces is
that two vectors selected at random have a very high likelihood of being
orthogonal.  If you consider additive white noise as one such vector and
the mid/high frequency watermark pattern as another, then additive white
noise should not impact watermark detection at all.

- Jeffrey


At 08:54 AM 12/10/2004 +0000, krutarth bhatt wrote:
>Hello All
>
>I have some doughts from the paper
>
>"Discrete Wavelet Transform based multiple watermarking scheme"
>
>By Raval Mehul & Rege Priti P.
>
>(1) Authors say that low frequency embedding are robust to geomatrical=20
>attacks
>
>(2) Middle & High frequency watermarks are robust to Noise adding &=20
>Nonlinear deformations of gray scale.
>
>I dont understand how they are ?
>
>can someone clarify my doughts?
>
>Thanks in advance.
>
>Krutarth

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
Dr. Jeffrey A Bloom, Sarnoff Corporation, 201 Washington Road, CN 5300,
Princeton, NJ 08543-5300 jbloom@sarnoff.com,
http://www.geocities.com/Jeffrey_Bloom, (609) 734-3287,
(609) 734-2662 fax

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