Proceedings Article | 30 May 2013
KEYWORDS: Cameras, Light sources and illumination, Optical filters, Visible radiation, Ultraviolet radiation, Sensors, Cultural heritage, Multispectral imaging, Calibration, Infrared imaging
In the world of Cultural Heritage the first concern is all about Conservation of the works of art. A piece of art in bad
shape is meant to deteriorate to an irreversible stage. To avoid this, quite often it's needed to go through one or more
cycles of restoration to clean and consolidate the various elements of the piece.
The very second concern, once the work of art is restored and in good and stable shape, is its fruition. At the end of the
day why one should do all that restoration work if nobody then can access and view? Yet viewing and enjoying an
artwork means that a visitor would be able to see it at its best, and this means, almost always, to have a good lighting
system. Today, both restoration and fruition can greatly benefit of all the available technologies, and achieve very high
level quality. The goal of this paper is the development of an exposimetric system suitable to be extremely useful as a
tool for the the non invasive analysis, as well as for the lighting design and lighting systems monitoring.
Many diagnosis techniques that are used before the restoration stage, require a suitable lighting system to allow to extract
from the painting the maximum amount of information through the acquisition of images in the range of visible as well
as UV and IR light. A standard exposimeter is for its own nature, sensitive only to the visible light, constrained by the
standard photometric sensitivity curve V(lambda). A wide band exposimeter would be, on the other hand, an invaluable
tool to get higher precision and to speed up multispectral wide band images acquisition, avoiding time wasting fail and
try cycles to record the subject under wide spectrum conditions.
The same equipment can be used to monitor the quality of the light in a expo lighting system at, for example, a museum
or a gallery. The light hitting a piece of art has to allow the visitor to see and appreciate all the color shades, and to
appreciate the contrast of dark and bright areas due only to the painting (and not to a jeopardized light). At the same time
the light has not to arm the surface and the pigments, with for example an excess of UV, that can influence the chemical
bonds, or an excess of infrared that could rise the temperature to damaging levels.
