How do I implement(in C code) the embedding of a visual fragil
watermark into an image?  The watermark is fragile so that I will be
able to tell if the image was modified in anyway.

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Request for Question Clarification by studboy-ga on 07 May 2003 23:37 PDT

Hi jemjem

Would the following do?  Both algorithms and source codes are included
(I believe these are fragile or semi-fragile):

C:
http://www.cosy.sbg.ac.at/~pmeerw/Watermarking/
C++ (convertible into C):
http://home.att.net/~steamedcrab/

Let me know if this surfice as an answer.  If yes, I can turn this
clarification into a formal answer.  Thanks.

I don't know the specifics, but Digimarc essentially created this
market.  They may have some APIs available (on a subscription basis?)
that could handle this for you.

http://www.digimarc.com/

I don't want to use other people's tool.  I want to see the actual
code for the implementation of the watermark imbedding and
verification.

I had spend about two days trying to find what I'm looking for on the
net, and I already saw cosy.sbg.ac.at in my own search.  It does not
have the type of algorithm I'm looking for.  As for att.net, it's the
wrong language so I can't make heads or tails of it.

I'm not an expert on C programming(far from it).  That's why I'm
looking for something simple and straight forward.  I don't even know
if that's possible for what I'm trying to do, but I have all my
fingers crossed and I'm hoping you can help me find the answer.

JemJem,

The watermarking images is just a specific application of steganography, 
the hiding of a message within another message. I found a site with a 
good list of steganography softare, including many free, open source
distributions. The site is down at the moment but we can use the 
google cache (the url of a cached page is long, so I used tinyurl.com
to map it to something more manageable).

Steganography Software

http://tinyurl.com/bapx

Here are just a couple of distributions that look promising (in that 
they're free and include c source code):

Hide4PGP
http://www.heinz-repp.onlinehome.de/Hide4PGP.htm

Hide In Picture 
http://www.brasil.terravista.pt/Jenipabu/2571/e_hip.htm


If this is still too much (these are working applications and were not
written for illustrating techniques) then maybe you want to see if you 
can get hold of a textbook. Here's one:

Digital Watermarking; Cox, Miller, and Bloom. Academic Press. 

This has C Source code, but it may not make much sense without 
the book. Here's a link to the publishers site, where you can 
download the source.

http://tinyurl.com/basb

Hope this helps.

Eadfrith

Will it be possible for me to get just the code instead of all these
links?  I did spend some time looking at the internet before resorting
to google answers.  I couldn't really understand most of them.  I did
look at the links you provided last and none of them are very straight
forward.  Anything easier?  Please?
 Thanks.