RE: [WM]: one basic question for fragile watermarking

["Zou Dekun" <dekun.zou@Thomson.net>]

Zhao,

Two approaches can solve the problem.
1. When extract "hash" bits, use a subset of the host image. When embedding, use those values not selected for hashing.
2. Use reversible watermarking scheme. At the detection stage, the original host image can be recovered.


Best regards,
Dekun

-----Original Message-----
From: watermarking-owner@watermarkingworld.org
[mailto:watermarking-owner@watermarkingworld.org] On Behalf Of Zhao Stephen
Sent: Tuesday, April 11, 2006 1:55 AM
To: watermarking@watermarkingworld.org
Subject: [WM]: one basic question for fragile watermarking

Dear all,
Recently I surveyed some paper on "fragile watermarking" for authentication application.  In these paper, a general scheme is to
first extract a fingerprinting from host image such as "hash", embed the "hash" bits into the host image by watermarking method. In
detection phase, the "hash" bits are re-extracted from the watermarked image for final authentication.
I am puzzled by one question: the extracted "hash" are really identical before and after the "hash"  is watermarked into the host
image, considering watermarking tech is performed by modifying the host image.
Maybe it is contradicting.

Thanks
                            Zhao


________________________________________________________________________
______

Watermarking Mailing List - http://www.watermarkingworld.org/ml.html
To unsubscribe send email to "majordomo@watermarkingworld.org" with "unsubscribe watermarking YOURMAIL" in the body.
________________________________________________________________________
______


______________________________________________________________________________

Watermarking Mailing List - http://www.watermarkingworld.org/ml.html
To unsubscribe send email to "majordomo@watermarkingworld.org" with
"unsubscribe watermarking YOURMAIL" in the body.
______________________________________________________________________________