指纹图像二值化是指纹细化处理的前提,是指纹识别预处理的一个重要部分.为利用指纹图像所具有的纹理特性,将指纹的方向信息引入到二值化处理过程中,综合考虑指纹的方向信息和自适应选择局部阈值,提出了一种结合方向信息的自适应局部阈值二值化算法.与自适应阈值法做了对比实验,实验结果表明,该算法具有更好的二值化效果.算法本身还具有一定的连接指纹图像中断线的能力,这对提高细节特征提取结果的准确性具有重要的意义.

Fingerprint image binarization, as one key step of fingerprint image preprocessing, is the precondition of fingerprint image thinning. In order to utilize the texture character of the fingerprint image effectively, the paper introduces the orientation information in fingerprint image binarization. After considering the fingerprint image orientation information and self-adapt local threshold synthetically, this paper brings forward a kind of self-adapt local threshold binary algorithm using the orientation information. The contrastive experimental results indicate that the presented algorithm can achieve more exact binarization results than the self-adapt binarization algorithm. Moreover the algorithm can repair the disconnected line in the fingerprint image in a certain extent. The algorithm is important for improving the minutia extraction precision.