We propose strategies for reducing the number of light sources in a scene preserving the illumination obtained with the full set of light sources. This reduction comes as a post processing to a mathematical phase of an inverse lighting method we developed. The method allows to graphically define a targeted effect in a scene with fixed geometry, the computer producing causes that lead to the desired effect i.e. a lighting configuration (number of light sources, their position and self exitances). Of course our reduction strategies may also be used in the case of direct lighting.