Abstract: As the color recognition rate of the license plate is not high in complex environment，a hierarchical method of color recognition of the license plates is presented in this paper.First，it projects the original color image to the HSI color space，and the preliminary recognition result is according to the different distribution of different license plate in HSI color space.Then the prospects of the license plate are extracted from the backgrounds，whose color information is used for getting the second recognition result.According to the above two steps，it gets the ultimate recognition results.The experimental results show that the proposed method is quite effective and robust.

Key words: HSI, color recognition of license plates, mathematical morphology

摘要： 针对复杂环境中车牌颜色识别率不高的问题，提出了一种分级的车牌颜色识别方法。首先将原始彩色图像投影到HSI空间，根据不同牌照在HSI空间的不同分布进行初步识别，接着提取出牌照的前景和背景，并根据各自的颜色信息再次进行识别，最后综合上述两个步骤得到最终的识别结果。大量实验结果表明，该方法颜色识别准确率高、适应性强。

关键词: HSI, 车牌颜色识别, 数学形态学