Hyperspectral imaging

Last changed: 20 August 2020

One of the specialties of FBT is the laboratory acquisition of hyperspectral images of biological samples (wood materials, food products, seeds, fruits etc.)

The Malvern MatrixNIR hyperspectral imaging camera (right) is based on an Indium-Gallium-Arsenide detector and a Liquid Crystal Tunable Filter. It makes images of size 320x256x118 (wavelengths 960-1662 nm) of objects that are 62 mm x 49 mm. This means that each pixel is 0.19mm x 0.19 mm. Higher magnifications (e.g. for 12 mm x 9 mm objects) can be achieved by changing objectives. Illumination is with four quartz-halogen lamps with adjustable current.

The Videometer (left) setup makes multivariate images of size 2000 pixels x 2000 pixels in 19 wavelength bands of 375-1050 nm. The illumination is by LEDs that are lit in sequence. An integrating sphere gives even illumination of objects size 100 mm x 100 mm (pixel size 0.05 mm x 0.05mm).

 A simulated plastics recycling image (below) was collected with the Malvern camera. The result is a 320 pixels x 256 pixels x 118 wavelengths image. The picture shown is the first principal component score image after cropping, cleaning away bad pixels, background removal and transformation for removing uneven illumination. The colors, chosen to represent score size, clearly show the chemical composition of the plastic materials: red PE, blue PET and yellow-orange PP. Equal or similar color means equal or similar chemical composition. In this way a complete detailed classification of different materials can be obtained.


Paul Geladi, Professor
Department of Forest Biomaterials and Technology, SLU
paul.geladi@slu.se, +46 90-786 87 93, +46 70-270 94 73