The VASARI project developed a colorimetric scanner system for direct digital imaging of paintings. It provides higher colour accuracy than conventional film and high resolution, so it can be used to replace film photography. The project was funded between 1989-92 but technical development continued, including improvements in lighting, software, calibration and colour targets. This was the start of many EU Cultural heritage-based research projects I was heavily involved in.
The scanner moves a CCD camera to capture areas which are later “mosaiced” together into a higher resolution image, which is calibrated to CIE Lab values by using images of test charts. The whole scanner can be moved back to allow paintings to be installed. The camera can move slightly forwards/backwards to allow automatic focusing (and hence keep the resolution the same).
The scanner in the National Gallery is used to produce images with 20 pixels per millimeter of paintings from seven colour bands spanning the visible spectrum. These images are so large (around 1GByte each) they required powerful VIPS image processing software and have been stored on optical disks, CDr and now RAID systems. They are used for publishing, scientific analysis and conservation. This includes studies of surface texture and colour change.
A second scanner was built in the Doerner Intitute in Munichwhich is also used for infra-red imaging. The MUSA project produced a third scanner in the Uffizi Gallery in Florence.
The London and Florence scanner mechanics were built by Time and Precision, Basingstoke UK. They had to be strong enough to stay straight and consistent as the camera moved.
Links to:
the official EU page on the project
a video we created with SUN microsystems
A National Gallery paper by David Saunders and John Cupitt