2.4. Image preprocessing
All the acquired hypercubes were processed and analyzed using MATLAB 7.13.0.564 (The MathWorks, Inc., Mass., USA). Each hypercube was corrected from the dark current of the camera prior to segmenting the region of interest (ROI) of each sample. To correct the spectral images, a dark image B and a white image W were obtained by covering the lens with a cap, and by taking an image from a standard white reference (Spectralon, Labsphere,