Digital Watermarking and copyright 

by Julian Jackson (1368 words)

	How do you protect your images in a digital age, where copying them is no more than a mouse-click away?

	This is a question that has been worrying both picture researchers and libraries for quite some time. Computer technology has made the copying and transformation of images, formerly a slow, tedious and expensive process, into something anyone can do in a manner of seconds.

	But now computer technology itself is restoring the balance: a new method of inserting copyright information into images called  digital “watermarking” or “fingerprinting” has come onto the market.

	This means putting an invisible, or “virtually imperceptible” code into the image which identifies the creator, and how to contact them. Ideally this code should be tamper-proof, and able to withstand image transformations such as cropping, colouration, or even distorting with one of the many ‘filter tools’ available in Adobe Photoshop, for instance. And survive crossing different media, from the digital scan to a print medium to a TV screen and back again....

	At present there are two main companies in the field, one Digimarc, is US and market leader, by virtue of having its software incorporated in many graphics applications including Photoshop 5, the latest update of the standard photo-manipulation program.
The other is British: Signum Technologies, whose program likewise can also ‘plug into” Photoshop, and other similar products.

	How does it work?  You take your digital image, and make a copy while running the fingerprinting program. An id code is then tiled into the picture.  Imagine a tiny, watermark in each 100 by 100 pixel area. The companies claim it is “imperceptible” rather than actually invisible, that is if you scrutinised a watermarked and non-watermarked copy side by side you might notice some minute difference in colouration. In practical terms these invisible codes are embedded in the very structure of the pixels.  To see if you have a watermarked picture, you use a reader program (distributed free, to encourage use), which comes up with a copyright statement, and id number, and who to contact to get the creators name, contact address, agent ,e-mail shoe size, whatever. The reason for not embedding such details in the image is that the watermark has to be quite small for technical reasons, and of course the copyright address could change, so the numbers are held at a central registry that can be easily updated. The advantages are manyfold - it will discourage fraud: who’d want to take the chance of being sued when the photographer can prove with absolute certainty that they hold the creator id (you can’t put more than one id on one image. On a montage, each section would retain its separate copyright id).  It will encourage people who want to re-use the photo or commission the photographer.  Doesn’t that sound great, fellow researchers, to be able to run a detector over a photo, make one phone call, and find out the photographers phone number? No more having conversations like this: “I saw this pic in Slam magazine, yes I know it went bust but someone told me you own the copyright...ah I see, no records were kept...the former picture editor,um, sorry...I tried her number already....”

	The advantages are numerous: even losing the slide-mount doesn’t mean you don’t know who the creator is (I say creator, because we could apply this to fine arts, purely computer graphics, any form of digitised image, rather than just photography).  It will deter fraud and encourage good behaviour;  give creators an additional revenue stream, from images that might have been distributed via any electronic media.  Both companies are testing ‘web spiders”: which crawl round the net looking for their copyright signature, and would automatically identify the creators, via e-mail where they found them. I’m sure a short sharp “flame” (nasty e-mail) would bring a cheque in the post, as an illegal copier wouldn’t have any defence “I didn’t know it was a copyright photo” when a quick pass with a detector would bring it up on the image (*****see photo opposite******). Naturally, in any file header you would put a copyright notice that the picture had been watermarked, which would further deter those who might consider cheating (Photoshop 4 does this automatically to images that have been “Digimarced”) 

	Both programs have undergone extensive testing, and have recovered watermarks from digital images  which were reproduced in print media, sometimes in small and crude form:(I mean local newspapers). In the jargon they are ‘robust” Digimarc is free if you buy Photoshop, with registration $99 PA.   Highwater’s product costs £60 for an individual, or £995 for a heavier duty version to do 50,000 images plus £25 P.A. for their register.

	Sounds like a dream deal. Unfortunately here’s where it turns into old fashioned war film: with the thorough  but self-effacing Brits conflicting with brash and megalomaniacal Yanks.

	Digimarc were there first, and seized the largest market share, having astutely bundled their product with leading imaging software, and they are also being evaluated by big players such as Getty Images, owners of the Hulton, and Corbis, Bill Gates’ subsidiary. Though because few images are actually sent out digitally yet, this is very much in the proving stage. We are looking at a new technology, with significant applications, not just to images, but music and video as well. But like most innovations, it has problems and this is where Digimarc fall down:

	Their technology and their income model are deeply flawed. Firstly, it is vitally important that the watermark is virtually tamper-proof; unfortunately, it seems that the Digimarc code is quite easily removable with the right tools, there is even a pretty irresponsible web site that boastfully offers software to eliminate it in seconds. Alan Bartlett, of Signum Technologies, while remaining very confident that their code is “an order of magnitude more complex.  I’m not saying its impossible to remove, but it would take a very expert hacker, or mathematician days to remove just one”  But he feels that any loss of credibility by Digimarc damages all the reputation of all watermarking methods. The on-line version of the New York Times (CyberTimes, November 11th 1997) went round various websites claiming to be protected by Digimarc and found that: “But it turns out that PictureMarc often fails to leave a discernible watermark on the kinds and sizes of images used most often on the Web.”  The code seems particularly vulnerable to JPEG compression, one of the widest-used methods to reduce image file sizes to make them practical for the internet.

	The second problem is that Digimarc’s main source of income is the register: currently they charge $99 per annum fee and they control it. I dunno about you, but I remember when satellite TV came out, and virtually everything except the movie channels were cheap, then the fees got jacked up and up. I feel that might happen to Digimarc. Not to mention that the appropriate place for this information is some kind of not-for-profit national body. There isn’t one here at the moment but a group of photographers, and agencies including BAPLA are setting up the Visual Creators Index, which is to be an independent registry of creators in all media, making full use of the digital fingerprinting as an identifier.  Signum Technologies do not ,in principle, see any problem in turning over their registry to be administered by such a body once the details about how it should be run have been ironed out.

	I think that we should support and use this new digital watermarking technology as it offers to solve some of the problems we picture researchers face, and it will undoubtedly improve in the future: but my advice for now is: download both readers from the web sites below (they work with a variety of programs for both PC and Mac) but if you were to pick one to copyright images then use our own markedly superior Signum Technologies

Signum Technologies Ltd,
2-6 St George’s Business Park
Alstone Lane,
Cheltenham ,
Gloucs GL51 8HF.
Tel: 01242 221390.
Fax: 01242 251600
website: http://www.signumtech.com

Digimarc Corporation,
521 SW 11th Avenue
Suite 200
Portland, OR 97205
USA
Tel: 001 503 223 0118
website: http://www.digimarc com

Visual Creators Index: www.vci-uk.com, www.vci-registry.org

About the author:

Julian Jackson is a internet consultant to the digital imaging industry who is heavily involved in online research and web site design/marketing.  He can be contacted by e-mail :julianj@totalise.co.uk