基于波形分形维数的车牌定位算法

Algorithm for Car License Plate Location Based on Fractal Dimension of Waveforms

根据车牌区域内字符分布特点,提出一种基于波形分形维数的车牌定位算法。该算法采用滑动窗法对照片中每一行灰度曲线计算窗口内曲线段的波形分形维数,得到一幅二维波形分形维数特征分布图,通过对分布图进行处理可分割出车牌区域。实验结果表明波形分形维数能有效表征车牌内字符的排列特征,且不受背景环境、车牌颜色和类型的影响,对车牌倾斜度也不敏感。对1000张包含复杂背景照片进行定位的准确率达到98.9%。

According to the distribution of the characters on a car license plate （CLP）, a new location method based on distribution of fractal dimension of waveforms （FDW） is proposed in this paper. Using the method of sliding windows, the FDW for each line gray curve of every photo is estimated and two dimension distribution of FDW are gotten. Through processing the distribution of FDW, the CLP zone can be segmented easily. The experimental results show that FDW is effective for the attribute of the characters alignment on CLP and it is not affected by the background, the color and the type of CLP. Besides, the proposed algorithm is not sensitive to the sloping license plate and the accuracy rate of location for 1000 complicated background photos reaches 98. 9%.