Cameron Trowbridge
ILS 603: Image Databases
Individual Paper
October 13, 1995

Image Protection for Archives, Special Collection Libraries and Museums in the WWW Environment

With the growing number of public institutions making their debut on the World Wide Web, the issue of implementing methods that will prevent the misuse of the material they mount for public consumption has become increasingly important. This is particularly true for institutions that are exhibiting digital representations of photographs, rare books and manuscripts, and original artworks on the WWW . As the audience for these kinds of collections grow, so does the potential for their misappropriation. The only way to prevent, or at least curb, the widespread pilfering of copyright protected images is to develop policies for displaying primary source material and to examine methods for protecting them from re-use without adequate credit or in an unauthorized way.

When I first began research for this assignment I thought my problem would be synthesizing the overwhelming amount of information that I would find on the Internet. I was wrong. Instead I spent a great deal of time looking at Web sites for Archives, Special Collections libraries and Museums. While many of these sites offer impressive samplings of what their collections have to offer, only a few appeared to take any precautionary measures to prevent unauthorized or illegal further use of those digital facsimiles. Generally, most of the sites included copyright statements and conditions of use which explained in explicit detail what kind of uses were, and were not, allowable for that particular assortment of images.

I was more successful in my search for information which discussed the different kinds of encryption technologies that are available and that could be used to protect images. I was also able to find a few sites which employed lower-tech solutions to limit the potential for exploitation of their digital collections.

While I did find a lot of literature on encryption, that vast majority of it pertained to the safe-guarding of text-based data by transforming it into an unreadable form by anyone without a secret decryption key. The purpose of encryption is to ensure privacy by keeping the information hidden to everyone other than those for whom it is intended. An example of this type of encryption is public-key cryptology. In order for public-key cryptology to work, the sender and the receiver of the information must both be in possession of the same key. The problem with this method of cryptology is security, as the secret key must be conveyed by some means of transmission other than electronic.

Another type of key cryptosystem is PGP, or Pretty Good Protection. It is more secure than public-key cryptology because it is more resistant to sophisticated forms of analysis designed to decode the encrypted text. While neither of these methods of encryption lend themselves well to digital images, PGP can also be used to apply a digital signature to something without encrypting it. Once a digital signature is created, it is impossible for anyone to modify the signature without the alteration being detected by PGP. In this way, something like PGP could be used to attach the owning institution's name right into the image as a means of identifying it later, should its misuse be discovered.

Similar to the digital signature is the digital watermark. The basic concept behind digital watermarking is to provide a secure means to confirm the origin, ownership and authenticity of digital works. This is accomplished by using data-security technology that embeds identifying information into the image file in a random fashion that can only be reassembled and read with the aid of an electronic key. The only person who has access to the electronic key that makes the watermark readable is the publisher or copyright owner.

While the information that is encoded in the images may be very useful to the owner of the images, it may also be beneficial to the viewer. For instance, they may want to know who needs to be contacted in order to gain permission to reproduce a specific work. There is a watermark currently in development which will satisfy the needs of both owner and user. It will allow for two watermarks to exist in the same file: one known only to the holder of the key, and a second one which is visible to the viewer. While encryption and watermarking address identification issues, they fail to adequately solve the problem of unauthorized re-use of digital image facsimiles made publicly available by museums and historical repositories. Neither the digital signature nor the watermark can prevent the illicit copying of images; however, the copied images can be permanently damaged if there is any attempt to remove or erase the encoded information from them.

At the moment, the two most prevalent methods for protecting images available on the Internet seem to be mounting low to medium resolution images and labeling the images directly with the institution name. I found a couple of institutions which employ one or both of these techniques. The Dallas Museum of Art uses both processes. Their images are of low to medium resolution which is sufficient for viewing the information on a computer monitor via a browser. They are not of a high enough resolution that the co-opting of the digital facsimile might deprive the copyright holder of commercial benefit or intellectual acknowledgment. As an added security, a banner along the edge of the image contains the following message "Copyright, Dallas Museum of Art. For educational use only, not a public domain image." While this may appeal to the guilty conscious of some would be pirates, for others the banner could easily be discarded in Photoshop or some other kind of image processing software.

One of the other sites that uses labeling is the National Museum of Art at the Smithsonian Institute. At the same time that they have chosen to offer high-resolution images to their Internet patrons, they have marked their property accordingly with a copyright statement and their name. The National Museum of American Art is also one of seven museums who make up the Museum Educational Site License Project. As a participant of this project, their images are made accessible only to member institutions who agree to the conditions of use as set down by MESL. By making their collections available to a limited and specialized audience, they reduce the risk of possible misuse by unauthorized users.

The most interesting method I encountered, and perhaps the most crude, was the site belonging to the National Library of Medicine. Their image database, "OnLine Images from the History of Medicine", provides access to nearly 60,000 images, many of which are copyright protected photographs. To prevent unauthorized re-use of these image files, they have resorted to drawing diagonal lines through all the images known or thought to be copyrighted. While not the most aesthetically pleasing way to go, this is an effective method of preventing such re-use. The line is distracting but not obtrusive enough to make the image unreadable. In addition, policies regarding use and a strong copyright statement are prominently displayed on this Web site.

My lasting impression of the sites I visited was that there has not yet been enough done to ensure that collections of digital material will not be re-used without proper credit or in an unauthorized way. In their earnestness to establish a presence on the Web, they have may jumped too far ahead of themselves. Archives, special collection libraries and museums who are mounting, or intending to mount, exhibits of their collections on the World Wide Web need to consider more than just the logistics of digitizing their works and user access to them. The development of strong copyright statments and conditions of use are crucial. More critical still, is the implementation of techniques which will either encode invisible information about copyright and use restrictions for digital images or visable labeling that will accomplish the same thing.


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