Virtual slides: high-quality demand, physical limitations, and affordability.

Virtual slides (VSs) have been around since the beginning of telepathology. As recently as a couple of years ago, only single small images could be acquired, and their distribution was limited to e-mail at best. Today, whole slides can be acquired, covering an area up to 100,000 times larger than that possible only a few years ago. Moreover, advanced Internet and world-wide web technologies enable delivery of those images to a broad audience. Despite considerable advances in technology, few good examples of VSs for public use can be found on the web. One of the reasons for this is a lack of sophisticated and integrated commercial solutions covering the needs from acquisition to delivery at reasonable cost. This article describes physical and technical limitations of the VS technology to clarify the demands on a VS acquisition system. A new type of web-based VS viewer (vMic; http://alf3.urz.unibas.ch/vmic/) open to public use is introduced, allowing anyone to set up a VS system with high usability at low cost.