指纹自动识别系统中的关键技术一方向图

指纹方向图具有真实性、渐变性、抽象笥的特点，能以简化的形式直观地反映指纹图像最基本的形态特征，因此在指纹自动识别系统中具有重要的研究价值，目前方向图已被广泛应用于指纹图象增强、纹型特征的提取、指纹的自动分类、方向模板匹配、编码重构等许多关键处理环节，特别是以指纹方向图为基础构建的Gabor滤波器进行指纹的沿纹线方向滤波，收到了非常好的滤波效果，笔者系统地介绍了近年来发展起来的求取指纹方向图的方法，对其时间快速性对噪声的鲁棒性进行了比较，提出了每种方法进一步改进的思路，最后对方向图在指纹自动识别系统中的典型应用作了分析，指出了进一步的研究方向。

A Key Technology in Automatic Fingerprint Identification System:Directional Image

Because fingerprint directional image represents the basic structural feature really and abstractly, It has very important research value in automatic fingerprint identification system. Now it has been widely used to solve the problem of image enhancement, global feature extraction, automatic classification, template matching and image encoding. Especially the Gabor filter based on directional image gets a marvelous effect, which can filter the noises along ridges. Combining the author's research work, several newly developed methods to get directional image are introduced. The performance of real-time and robust to noise of these methods are assessed,and the mending methods are presented also. In the end, the typical applications are systematically overviewed and the direction for further study is provided.