The multispectral imaging technique consists of imaging a given scene at various wavelengths of interest, each one containing a different spectral information. By analyzing this spectral content, the chemical species that are present can be localized on the image and identified by reconstructing their spectral signature. In this way, following Ebbesen's seminal work in plasmonics [1], purely metallic or hybrid metallodielectric structures [2, 3] seem to be ideal candidates to perform spectral filtering due to their extraordinary transmission efficiency [4] and polarization selectivity. Moreover, their compact feature makes it possible for them to gather in wide arrays of filters that, once integrated into a cooled infrared camera, can achieve real-time multispectral imaging [5]. As seen in Figure 1.d. the spectral signature reconstruction of a chemical species strongly depends on the number of filters and their transmission spectra for the designed matrix. In order to improve the multispectral camera, a complementary approach consists of changing the filter design to realize a tunable filter whose spectral shape can be adjusted in real time according to the imaged scene. We focused our attention on the superposition of subwavelength gratings which seems to be a structure of great potential for multispectral imaging applications [6, 7].