Users
http://iipimage.sourceforge.net : IIPImage use VIPS to build their image pyramids. http://sourceforge.net/projects/libfvs : LibFVS, a content-based retrieval package, uses VIPS. PARSEC : The PARSEC benchmark suite uses VIPS as one of it's sample applications. VASARI, MARC, VISEUM, ACOHIR, CRISATEL, ARTISTE and MUSA : These EU projects all used VIPS as their image processing library.
University of Southampton : The Department of Electronics and Computer Science at the University of Southampton use it as an image processing framework in research projects. Imperial College, London : The department of Experimental Medicine at Imperial College are using it to analyze medical images. The National Gallery, London : It's used at The National Gallery for most of their imaging research. The National Gallery's Print on Demand service is all VIPS behind the scenes.
VIPS is also used in a number of other labs, museums and galleries around the world (including MOMA, the Louvre and BStGS), mostly for infra-red reflectogram mosaic assembly.