A fully automatic real time system for the characterization of automotive headlamps

In this work we describe a fully automatic real time system, based on a CCD camera, for extracting the geometric parameters of the light profiles projected by automotive headlamps. Our system is capable to automatically adjust to a wide range of light sources of different power allowing, through a locally adaptive thresholding algorithm, the automatic detection of the dark-light border of a beam profile as it would be perceived by an experienced human operator. The extracted beam profile is processed in order to compute the position of geometric reference points provided by current regulations (i.e the "elbow" point). In order to validate the measuring system and to achieve accurate ground truth data, the headlamp has been mounted on a special three-axis numerical control unit built on purpose. Experimental results, carried out on a large number of different headlamps, show that our method is able to achieve accurate measurements in compliance with current regulations. Finally, it is worth remarking that our solution is fully automatic and it just requires a simple setup procedure.