为解决视频检测中车辆阴影的影响，研究了常用的基于HSV彩色不变量的阴影检测方法，指出对于路面区域，阴影覆盖前后色调H分量和饱和度S分量近似不变的特性不总是成立，并以实例证明色调变换的奇异性也将导致该方法受限，继而提出了一种改进算法，利用两个色彩分量的变化量之比近似不变的特性进行阴影检测，其更适合路面环境。实验结果证明，所提出的改进算法能够较好地分离车身及其阴影，有助于准确提取交通信息。

Aimed to reduce the influence of car shadows on video detecting，this paper researched into the invariance of HSV color model which was often used in shadow detection，and pointed out that the invariance of hue and saturation before and after shadow casting is not always satisfied on the road area，and exemplified the limitations of the method caused by the singularity of the hue transform.Then an improved algorithm based on the invariance of the ratio of two different color variant values was presented which is more suitable for road environment.Experimental results show that the developed algorithm can distinguish the car and its shadow better and help to extract accurate traffic information.