针对被测汽车的停放方位对前照灯水平照射方位角测量结果存在显著影响，提出了基于图像处理技术的汽车前照灯光束水平照射方位角测量误差的修正方法。采用摄像头摄取检测位置汽车停放区域的图像，用OTSU自适应阈值分割算法得到汽车俯视外形轮廓图像，运用逐次逼近法求出汽车摆放偏置角，对检测仪测量结果进行修正，实现测量误差的自动修正。结果表明：该修正方法能有效排除汽车停放方位偏差对测量结果的影响，提高前照灯光束水平照射方位角的检测精度。

Because the measuring result of azimuth for automobile headlamp beam is prominently influenced by the longitudinal bias angle of the automobile location, a correction method for measuring error was proposed based on digital image processing. Camera was used to take the image of the automobile location. The profile of the automobile’s figure was obtained with the OTSU adaptive threshold segmentation algorithm. The automobile longitudinal bias angle was figured out by the successive approach method. Finally, the measuring result of headlamp tester was corrected by the bias angle so that automatic correction is realized. The experimental results indicated that this method could effectively obviate the influence of the bias angle, and greatly improve the measuring precision of azimuth for automobile headlamp beam.