The Virtual Lightbox is a software tool for comparing images online. Comparison, what John Unsworth calls a "scholarly primitive," is a basic and probably intuitive operation that is nonetheless not well supported--for images anyway--by conventional Web browser technology; that is, users have no ability to move, juxtapose, or otherwise reposition images beyond the configuration in which they are delivered by a static page layout. As rich image collections continue to come online, it's becoming increasingly apparent that end-users lack the tools to exploit such resources to their full potential. The Lightbox is one attempt to meet this need. Though its target audience is in the academic humanities and the library and museum community, we expect the Lightbox to find users far removed from this sphere; indeed, we anticipate it will be of interest to anyone for whom images constitute an important data type.

The Lightbox currently exists as both an application and an applet (both programmed in Java). The application version, which was developed first, allows users to share images in peer-to-peer fashion: all users participating in a common session see the same images in the same on-screen configuration at the same time. Movement of an image and other operations are all globally propagated in realtime. Thus the application version functions as an image-based whiteboard. The applet version is something different. It has no peer-to-peer capability, but furnishes what we believe to be an extremely flexible environment for image comparison. Users can save the state of their session and re-open previously saved sessions. Its primary audience is developers who wish to add an image comparison tool to a Web-based image collection. Simple server-side scripting--we'll furnish some examples soon--allows users to populate the Lightbox applet in any number of ways. Version 2.0 of the applet was released in February 2004.

The Lightbox has been under development since July 2000. Full credits and acknowledgements are available here. The Lightbox is free software, distributed under the terms and conditions of the GNU General Public License. We ask that users publicly credit the Maryland Institute for Technology in the Humanities (MITH) and provide a link to this site:

http://www.mith2.umd.edu/products/lightbox/

Some users of the Virtual Lightbox may also be interested in MITH's Versioning Machine.