This paper discusses a low-cost multispectral imaging system for theidentification of pigments in artworks. It is composed of a full spectrummodified digital camera, a DSLR with the IR cut-off filter removed andsensitivity extended to about 360-1100 nm. A set of 12 interferential filterscovering the range 400-805 nm completes the equipment. The systemuses on-scene reflectance standards and the raw images are split inthe 3 CFA (color filter array) components (RGB). An appropriate set of 12RGB components was chosen to form the set of 12 spectral images tobuild up the reflectance imaging cube. This system was tested on a collectionof 54 historical and modern pigments and their reflectance spectrawere compared with a database of FORS spectra (360-1000 nm) ofthe reference pigments. The performance of this system was evaluatedagainst a commercial spectral imaging system equipped with the sameset of 12 filters, but mounting a conventional monochromatic high-sensitivityCCD. The performance of the digital camera system is comparableto that of the monochromatic CCD camera, but the latter providesmore accurate spectra thanks to its higher linearity, especially at theedge of the spectrum and in the condition of low signal. The proposedsystem is of interest for the art conservation sector because of its lowcost and because the same digital camera can be used for other technicalphotographic methods, reducing the weight and cost of the overallimaging equipment necessary. The proposed method implements a smallnumber of filters and consequently it has limited analytical capacity. Itmust only be used for an initial mapping of the pigments and this preliminaryidentification must then be confirmed by elemental or vibrationalspectroscopic methods.
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