Introducing liquid fuel inside an aeronautical combustion chamber is associated with several complex phenomena like droplet dispersion by turbulence, spray evaporation and combustion. In order to study experimentally the spray behaviour, under non-reactive and reactive conditions, Mie scattering images provided by the PROMETHEE-LACOM test rig have been processed. However, the transition between a 3D flow in the combustion chamber to a 2D planar Mie scattering images leads to some errors. The present paper focuses on the evaluation of these errors and the influence on the droplet spatial distribution. Results show that the droplet distribution remains practically the same between the 3D-2D transition. Moreover, the restriction error decreases when droplet density number increases and the projection error increases when droplet density number increases.