An apparatus includes an array of sub-diffraction limit-sized light receptors formed in a substrate having a light receiving surface. Each light receptor may be configured to output a scalar valued multi-bit element and to change state based on the absorption of at least one photon. The apparatus further includes an optical filter structure disposed over the light receiving surface, the optical filter structure having an array of filter pixels each having an associated passband spectral characteristic. A data element obtained from the array of sub-diffraction limit-sized light receptors is composed of a combination of a plurality of the multi-bit elements output from a plurality of light receptors that underlie filter pixels having at least two different passband spectral characteristics.