A multispectral image sensor includes a semiconductor layer and a number of pixels formed inside and on top of the semiconductor layer. Each pixel includes an active photosensitive area formed in a portion of the semiconductor layer laterally delimited by peripheral insulating walls. The pixels include a first pixel of a first type and a second pixel of a second type. The portion of semiconductor layer of the first pixel has a first lateral dimension selected to define a lateral cavity resonating at a first wavelength and the portion of semiconductor layer of the second pixel has a second lateral dimension different from the first lateral dimension. The second lateral dimension is selected to define a lateral cavity resonating at a second wavelength different from the first wavelength.