Using a tomographical transformation, a data processing method is developed to extend the Malvern line-of-sight measurements based on laser diffraction theory into pointwise spatial distributions of various spray characteristics including droplet Volume and number concentrations as well as all mean diameters of practical interest. The method has been applied to characterize the structures of sprays injected into still ambient air and annular air streams with various liquid and air flow rates, it is found that the various mean droplet diameters may have different tendencies,of radial variations, exhibiting their respective importance in characterizing sprays, and that the air flow can significantly modify the spray structure along both the radial and axial directions and may cause the dilution or accumulation of droplets in certain regions.