Coupling hyperspectral image data having different spatial resolutions by extending multivariate inter-battery Tucker analysis

Abstract: Hyperspectral imaging in various spectral domains is used to perform in situ biochemical analysis of biological material. In the present work, two complementary microspectroscopies—mid-infrared and fluorescence—were coupled to characterise maize stem cell walls. In practice, each microspectroscopy operates with its own resolution, infrared pixels covering a 5×5μm² surface and fluorescence pixels a 1×1μm² area, making the coupling of both spectral ranges through unfolding the spectral images not straightforward. A data structure that preserved the spatial resolution in the two domains was built resulting in a two-way data table with a spatial way and a spectral way, paired to a three-way data table with two spatial ways and a spectral way. The multivariate inter-battery Tucker analysis was investigated in order to give each spectral domain a symmetric role. First, the inter-battery Tucker analysis was applied after averaging the three-way data table under the third mode to obtain a classical two-way data table. This led to work at the lowest resolution. Second, the method has been extended for coupling the three-way data table with the two-way data table. The spectral loadings were similar in both cases showing that phloem cell walls were rich in hydroxycinnamic acids and sclerenchyma cell walls in lignins. The extended version provided with fluorescence scores that preserved the spatial resolution showing more fluorescence intensity in cell junctions. The strong point of the extended inter-battery Tucker analysis is to allow the joint analysis of the two tables without altering their qualities. [Copyright &y& Elsevier]