Type: (Multi/Hyper) Spectral Imaging
Overview
Hyperspectral imaging is based on reflectance spectroscopy which allows the collection of reflectance spectra in each point of the field of view. The hyperspectral image cube obtained contains both the spectral and the spatial distribution of different materials on the analyzed surface.
The integrated scanning system characterizes this instrument which can record the image and spectra directly from a photographic tripod in front of the analyzed object, without any external parts in movement.
The obtained spectral information is suitable for dye and pigment identification by comparison with a wide database of reflectance spectra collected on materials used in the different historical periods in polychrome objects. Besides, hyperspectral images permit surface inhomogeneity in composition to be rapidly highlighted, leading to a mapping of anomalous deterioration parts and/or unknown restoration performed in the past.
VIS hyperspectral imaging is well adapted for almost flat artworks such as paintings, manuscript, drawing, etc. and it is completely not-invasive, easily usable in situ without any preparation of the artwork.
Technical Details
The SOC710 Hyperspectral Imaging System is a precision piece of equipment utilizing a high-speed, low-noise silicon-based CCD, high quality visible-to-near infrared spectrometer, integrated scanning system, and capture and analysis software. The SOC710 can record HS imagery at a rate of 4 megabytes of data every second (128-band elements per second at 12- bit resolution, 520 pixels per row, up to 33 rows per second). The system’s spectral response covers the visible and the first part of NIR spectral range from 0.4 – 1.0 microns. In order to obtain clear and smooth reflectance spectra on the whole spectral range, halogen photographic lamps are used as light sources, yet the instrument can also be used in normal lighting conditions with variable exposure times and gain.
Camera Specifications
• Spectral Band: 0.4 – 1.0 microns
• Number of Bands: 128
• Dynamic Range: 12-bit
• Line Rate: Up to 33 lines/second
• Pixels per line: 520
• Lines per cube (typical): 696
• Exposure Time: 10 -> 10^3 milliseconds
Further readings
- Delaney, J.K.,Zeibel, J.G.,Thoury, M., Littleton, R., Palmer, M.,Morales, K.M., René de la Rie, E., Hoenigswald, A.,”Visible and infrared imaging spectroscopy of Picasso’s Harlequin musician: mapping and identification of artist materials in situ”, Applied Spectroscopy 64, 584-94, 2010.
- Vitorino, T., Casini, A., Cucci, C., Melo, M.J., Picollo, M., Stefani, L., “Hyper-Spectral Acquisition on Historically Accurate Reconstructions of Red Organic Lakes”, Chapter “Image and Signal Processing”, Volume 8509 of the series Lecture Notes in Computer Science pp 257-264, 2014, Springer Ed.
Providers
MOLAB France: CNRS