An apparatus includes an array containing N sub-diffraction limit light sensors each having an associated light absorption activation threshold for switching from a reset state to an activated state, where the light absorption activation values lie within a range of values. The apparatus further includes a processor connected with a memory including computer program code, where the memory and computer program code are configured to, with the processor, cause the apparatus at least to perform estimating an intensity of light that illuminates the array based on electrical outputs of the array.