Unless collaboration is the major line item for this project, I'd use a networked asset management system, rather than MediaWiki.

It sounds from your description like you could get some budget to do it right. Look at Canto Cumulus or Extensis Portfolio. The server edition of either one is designed for what you need, rather than trying to cobble what you need onto the back of a collaborative authoring system, simply because it allows users to upload images over a web browser.

::::A revolution is interesting insofar as it avoids like the plague the plague it promised to heal. -- Daniel Berrigan :::: Jan Steinman http://www.EcoReality.org