一种基于交点权重图的指纹焦点检测方法

Fingerprint Focal Point Detection Method Based on Map of Cross Points' Weights

指纹参考点在指纹注册和识别过程中非常重要,能够有效减少拥有大规模指纹库的自动指纹识别系统的识别时间。指纹焦点是一种很稳定的参考点,而现有检测指纹焦点的方法的精度还有很大提升空间。基于从方向场生成的交点的权重信息,提出了一种精确的指纹焦点检测方法。首先,提出了交点权重图的概念以及从指纹方向场计算该图的方法。在分块方向场上,各个块中经过块中心垂直于块方向的直线两两相交得到一些交点,为每个交点根据对其期望焦点位置的贡献赋予一个权重,得到交点权重图。该图基本能保证理想的焦点位于其最大密度区域,从而提高焦点检测算法的精度和稳定性。然后将交点权重图用于迭代算法中,实现对焦点的精确检测。最后,在FVC2000Db2a指纹库上进行了实验,结果表明提出的方法在精度上比其他方法有明显优势,时间开销也在可接受的范围内。

The reference point is essential for fingerprint registration and recognition since it can effectively reduce the identification time on automatic fingerprint identification system with large scale database.As an extremely stable reference point,the fingerprint focal point still needs more accurate detection methods.In this paper,an accurate fingerprint focal point detection method based on map of cross points＇ weights was proposed.First,the definition and characteristics of the proposed map of cross points＇ weights are introduced.For the block-wise orientation field,from each block＇s center,a straight line perpendicular to the block＇s direction is produced,and each pair of such straight lines may have a cross point.By giving each cross point a weight according to its contribution to the expected position of fingerprint focal point,the map of cross points＇ weights is finally determined.The proposed map improves the accuracy and stability of focal point detection method since it can generally ensure the ideal focal point to be included in its maximum density region.Then an iteration scheme is utilized on map of cross points＇ weights to locate the focal point precisely.Experimental results on FVC2000 Db2a fingerprint database validate that the proposed method outperforms the others in terms of accuracy with acceptable cost of computational time.