There is now a growing trend not only to exhibit works of art in museums and galleries, but also to scientifically investigate the dyes and techniques used to create them. One way of penetrating the hidden layers of paintings to reveal the effect of ageing on the quality of the painting is through hyperspectral scanning of the artwork.
A hyperspectral scan provides information about the reflectance and transmittance of the examined part of the painting in the form of spectral curves. It is thus a non-invasive and non-destructive optical material analysis technique that provides both spectral and spatial information about the sample under examination with a resolution of up to 15µm per pixel size. Therefore, from hyperspectral images, we can infer detailed chemical and physical properties of the image that can reveal the painting technology, hidden layers and the aging process of the artwork.
If we use the wavelengths corresponding to the visible spectral region for hyperspectral imaging, we can obtain a very accurate measurement of the change in the colours of the painting as it ages. Wavelengths from the infrared region then provide information about the hidden layers of the image and the chemical composition of the dyes. This information then facilitates the selection of an appropriate method of image conservation and reveals the technique by which the image was created.
SPECIM has developed a special scanner that can be equipped with hyperspectral cameras with spectral sensitivity in the VIS, VNIR, NIR or SWIR regions for the purpose of examining artworks. The following figure then compares a conventional image photograph with a hyperspectral image (HSI) and an X-ray image. The comparison shows that the HSI image provides much more detailed information about the image than a plain photograph or X-ray image. More information about hyperspectral systems.
