Specifications

2
Executive Summary
Imaging is an important technique in the scientific examination of art. Its main use has been for
visual documentation. Photographs have long been used to document condition before and after
transit, microscopic examinations, conservation treatments, and so on. They are used to enable
color reproductions in books and from the Internet. Images using materials with spectral
sensitivities in such non-visible regions of the electromagnetic spectrum as infrared and X ray are
equally important to the visible spectrum. Although images are used to record scientific
examinations, they are used infrequently as an analytical tool, that is, the amount of colorant in a
photographic material would be used to relate to physical properties of the art. In contrast,
astronomy, remote sensing, and medicine have exploited this capability for many years. The
advent of digital imaging offers increased opportunities to exploit images for the scientific
examination of art. A research program is underway at Rochester Institute of Technology to
develop an image-acquisition system that records reflection information as a function of
wavelength. The system initially is limited to the visible region. The program is known as the Art
Spectral Imaging Project and the program is documented at http://art-si.org/.
The most important research goal has been to develop a practical imaging system that
provides high colorimetric accuracy with reasonable spectral accuracy. In order to be practical,
the system should use commercial products to the greatest extent possible. Any hardware
modifications should be straightforward. Software should be generalized and based on sound
mathematical principles such that it can be written for commercial applications.
This has been accomplished by performing hardware modifications to an area-color-
filter-array digital camera, writing extensive software to perform the necessary calibration, image
registration, spectral and colorimetric processing, and output to conventional file formats. This
technical report describes the imaging system, the color and imaging science (in the form of a
submitted manuscript to Studies in Conservation), and a listing of required hardware and software
to build an identical system to the Art Spectral Imaging Project camera.