The Precise Location Algorithm of License Plate Based on Gray Image
The Precise Location Algorithm of License Plate Based on Gray Image
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DOI：
10.1109/csss.2012.25
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发表时间：
2012-08
期刊：
影响因子：
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通讯作者：
Honghai Liu;Xianghua Hou
中科院分区：
文献类型：
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作者：
Honghai Liu;Xianghua Hou
车牌识别是城市智能交通管理系统中不可或缺的一部分，而车牌定位是车牌识别的关键步骤。传统的车牌识别算法主要采用边缘变换来定位车牌，准确度不高。提出了一种改进的车牌精确定位算法。摄像机拍摄的图像通常是彩色图像，因此首先讨论了灰度变换。然后将灰度图像转换为二值图像，而二值化的关键是如何找到最佳阈值。然后，消除背景干扰，利用垂直投影法找到车牌候选区域。然后，利用中值滤波算法消除图像噪声。最后通过水平投影找出车牌的水平区域，利用垂直定位得到车牌的精确位置。实验结果表明，该算法能准确定位车牌区域，有效提高车牌识别率。
License plate recognition is an indispensable part in the management system of city intelligence traffic and the location of license plate is a critical step in license plate recognition. The traditional recognition algorithms of license plate mainly adopt edge transformation to locate license plate, and the degree of accuracy is not high. In this paper, an improved precise location algorithm of license plate is put forward. The picture taken by a camera is usually a color image, so the grayscale transformation is firstly discussed. Then, the gray image is converted to a binary image and the image binaryzation' critical step is how to find the optimum threshold. To eliminate the background interference and use vertical projection method to find the candidate region of license plate is the next step. Then, using median filter algorithm eliminates image noise. Lastly, the horizontal region of license plate is found out by horizontal projection and using vertical location acquires the precise location of license plate. The experimental results show that this algorithm discussed in this paper can precisely locate the license plate region and effectively enhance the recognition rate of license plate.