中文摘要：

数字指纹预处理是整个识别过程的关键，全面分析各种预处理方法的特点，有助于改进预处理算法。通过实验说明了各种指纹预处理方法的效果；结合特征点变化，给出了各种预处理方法的评价；确定了基于傅里叶变换结合滤波和方向信息的频域滤波增强指纹的最佳方案，并提出了比较预处理算法的标准。

英文摘要：

The pretreatment of digital fingerprint is a key of the entire identification process, comprehensively analyzing the characteristic of every kind pretreatment method is helpful to improve the prctreatment algorithm. Through the experimental result of the various methods of pretreatment, the effects were illuminated; appraisal of every kind pretreatment method was given; the optimal scheme of enhanced fingerprints based on the Fourier transform and direction information was determined, and the standard of the comparing pretreatment algorithm was proposed.