digital watermark system

Aaron Wilson · November 9, 2005

hmmm... OK, I have a 20D, I know canon sales there water mark system or image thing... but is that the same as a "digital watermark system"? I know some one who had there images stolen and cropped down and then sold as some one elses. I usually add something into the iptc... but does a "digital watermark system" actually stay on or with the photo and the photo can't be edited or something a long that line or is it just like editing the iptc? What do you do or recumend? Should I shell out for canon's thing or go with a company and if a company who?

Andy · November 9, 2005

Aaron Wilson wrote:

hmmm... OK, I have a 20D, I know canon sales there water mark system or image thing... but is that the same as a "digital watermark system"? I know some one who had there images stolen and cropped down and then sold as some one elses. I usually add something into the iptc... but does a "digital watermark system" actually stay on or with the photo and the photo can't be edited or something a long that line or is it just like editing the iptc? What do you do or recumend? Should I shell out for canon's thing or go with a company and if a company who?

Canon does not have a digital watermark system, you might be thinking of the Data Verification Kit DVK-E2/E1.

Digital watermarking is in the imagefile itself, look at Digimarc as an example.

What is your intended use, what are you trying to accomplish?

And, why are you "flaming mad?"

Nikolai · November 9, 2005

Aaron
While I don't know exact techniques used by any particular data verification kit, please be aware that in general they only serve the purpose of the authentication of the original, not as a copy protection mechanism.
Nothing I know can beat print-screen or a scanner..

You can try, of course, but at a cost of hugely impairing the visible image quality, or for exorbitant amount of money (and it's still no guarantee)..
Just my 0.000002 of the f/stop.
HTH

luke_church · November 9, 2005

There's a whole bunch of work done on image copyright marking done by the people in the CL at Cambridge.

http://www.petitcolas.net/fabien/watermarking/stirmark/index.html

They're fairly clear. Protection of arbitrary images once they have been distributed should be done by perminantly overlaying obvious data in a visually significant area of the image. Anything else can be destroyed, even much more sophesticated systems that hide data in wave-lets are useless against even a moderately sophesticated attacker.

It's easier to look at these things by understanding the thread and working out how to counter that, you're not going to get absolute protection, but it might be possible for you to get enough protection that people won't bother trying to steal your images.

I think (but don't know) that the Canon system is generally for foresensics and evidence type applications so you can prove that an image was taken when it was and hasn't been tampered with. It's not a copy protection system.

What threat are you trying to defend against and how serious do you think your attackers are?

Cheers,

Luke

luke_church · November 9, 2005

Nikolai wrote:

Nothing I know can beat print-screen or a scanner..

Hi Nik,

There are systems out there than can deal with print-screen, generally through information encoding in spatial frequency space, rather than traditional colour space. Jeez, do the FFTs look wierd after some of them.

Oh yes, and the Chinese might get upset if they don't recognise the difference between them and really bad stegographic encoding...

Scanners are harder. There are some systems that can do a reasonable job in that you have to break the image quality fairly badly to break the copy protection system, again it tends to be spatial frequency.

You can also spam certain types of scanners and copiers by inserting frequencies that they are programed to recognise and refuse to process... Try scanning a modern bank note and opening it in Photoshop :-)

However in general nothing seems to be able to resist the attacks that include stretch-shear deformations and attacks at the spatial frequency or mosaic attacks.

I have a bunch of ideas to try out, but they need time, something I seem to be lacking at the moment :-( I'm sure they won't work, someone else would already be doing them if they would...

It's a question of how much you're worried, probably your average attacker isn't going to know how to do these things, but don't give them to an imaging specialist and expect to walk away with your copy protection system intact.

Cheers,

Luke

PS. I'll reply to your email this weekend with a moderately definitive answer.

Aaron Wilson · November 9, 2005

tnaks andy
Must be thinking of that other thing you said about canon, I hate people that still other peoples work and pass it off as theres... thats why for the icon...lol... I just want to be able to protect my work or images. The person is going through so much to prove it's his photo and not the other persons.

andy wrote:

Canon does not have a digital watermark system, you might be thinking of the Data Verification Kit DVK-E2/E1.

Digital watermarking is in the imagefile itself, look at Digimarc as an example.

What is your intended use, what are you trying to accomplish?

And, why are you "flaming mad?"

Nikolai · November 9, 2005

Luke,

luke_church wrote:

Hi Nik,

There are systems out there than can deal with print-screen, generally through information encoding in spatial frequency space, rather than traditional colour space. Jeez, do the FFTs look wierd after some of them.
...............................
/QUOTE]

Certainly, there are sophisticated (and usually costly) methods of protecting image identity. But, as with everything in the digital world, it also usually can be hacked and quite often hacking require much less efforts and resources than the protection itself..

Thanks for you help on that other thing:-)
Cheers!

Aaron Wilson · November 9, 2005

hmmm
I guess I would have to say the main reason to use a coding would be just to prove that it came from me if they down loaded the photo and tryed to use them... other wise if it's just a matter of them entering it into photoshop and crop it and the photo looses the info then there is no point. In a way it's to bad adobe dosen't have a system that will also work with paint shop to hide a code so that when a photo is loaded into there programs you can't edit the photo unless you have the password. I just would like to make it so if a photo is taken and cropped that i can still say it's mine and take action.. the person i know is going thru a bunch of hoops to prove it's his.. He just got a hold of the model in the photo to prove he took it.

digital watermark system

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