Vignetting correction for IRFPA-based train axle temperature measurement system

ABSTRACT Using thermal infrared imaging to obtain the temperature distribution of the train wheel sets is a new and promising temperature measurement method. The accur acy and precision of the method are suff ered from vignetting. In this paper, the vignetting coefficient function has been derived and imaging system calibration is introduced to compensate the measurement result error caused by the in consistent of the optic center and the image center. The vignetting correction is implemented on the hardware platform based on FPGA. Experimental results demonstrate that vignetting correction enhance the accuracy of measurement system. Keywords: axle temperature measurement; thermal imaging; vignetting correction; imaging system calibration 1. INTRODUCTION The emergence of train makes travel and resource flows be grea tly convenient. At the same time, the safety of trains has also been taken into account by people. Train axle temperature is one of the most significant factors of safety. Using infrared imaging equipment to obtain the temperature distribution of axle box is a new method of axle box temperature measurement. This new method can obtain the target much better than the traditional method.