Abstract—Various administrativeprovisions on vehicle headlamps are made by worldwide institutions for roadsafety. China developed the unique GB standards for testing the photometricperformance of vehicle headlamps. Currently, vehicle testing agencies usuallyuse a CIE A-α type goniophotometer to test a headlamp sample. Though with highaccuracy, the whole testing system is expensive and cannot realize real-timemeasurement of lightdistribution.In this paper, a novel headlamp testing method based on the concept of I-matrix(illuminance matrix) is proposed. The luminance distribution of the testingscreen is obtained from the digital image with a camera. Then luminance isconverted to illuminance through the matrix of nonlinear calibration curves.According to the I-matrix of the testing screen, the testing results of theheadlamp sample will be presented instantly through the programmed system.Experiment results on a set of headlamp samples reveal that no false testingpoint is found with the proposed method.

Keywords-vehicle headlamps; illuminance distributionmeasurement; passing beam assessment; I-matrix; nonlinear calibration