This study is part of the general context of thermophysical characterization of liquid metals with an aerodynamic levitation device and laser heating. The density measurements vs temperature of pure and alloyed metals are determined during cooling of the sample. The temperature and shape of the sample are measured, respectively, with a bichromatic pyrometer and filmed by a high-speed camera. The sample visualization is performed by backlighting, which has been preferred to self-illumination. The post-treatment process consists in a binarisation of each recorded image, and then, an ellipse is fitted on the detected edge. The density is directly calculated with the ellipse volume and the sample weight. The good agreement of experimental results on pure metals with the literature validates the method. Then, an industrial steel of unknown liquid density is characterized from 1750 K to 2250 K.