As opposed to strong light signals (> 10(8) photons mm-2 s-1), the construction of images from object sources with low level signals (< 10(2) photons mm-2 s-1) involves a probabilistic transfer- or point-spread function. The resulting images carry considerable uncertainty or spread, restricting resolution and quantification. In this paper we propose various strategies how to reconstruct object characteristics from very low light emissions by unfolding the imaging equation. Further, calibration techniques which help to associate light emissions with the decomposition of luminogenic substrates in a spatially selective way will be discussed.