Hybrid dual layer filter can be employed can be employed as filters. A multispectral imager comprises a two layer filter array monolithically integrated onto detector array, a top layer of pigment based filter and a lower layer of plasmonic nano-optic filter to make a low cost and narrow bandwidth filter without side leaking or side peaks. Multispectral imager comprises a microlens array, a mosaic patterned optical filter array underlying the microlens array and including a two-dimensional repetition of a unit mosaic pattern, and a pixelated detector array underlying the mosaic patterned optical filter array. The unit mosaic pattern comprises an array of composite filter elements having different peaks in a respective transmittance spectrum. Each composite filter element comprises a pigment based filter portion and a plasmonic nano-optic filter portion.