摘要：

已有傅里叶频域下的指纹增强工作存在指纹非平缓区域增强效果较差、块窗口尺度不易选择的缺陷。为此,提出一种新的基于曲面变换的指纹增强算法。把曲面变换(定位曲面区域并映射到二维数组)用于傅里叶频域下,根据曲面区域的频谱图选择合适的滤波器方向。将指 纹图像划分为平缓区域与非平缓区域,只对非平缓区域执行曲面变换以提高执行效率,引入复合窗口模板来解决块窗口尺度问题。实验结果表明,相比于非曲面算法,改进方案有更好的增强效果,增强后指纹的匹配正确率可以达到99.74%,同时,运行时间比曲面Gabor算法明显 降低。

关键词: 指纹, 傅里叶变换, 曲面变换, 滤波器, 指纹增强

Abstract:

The previous works enhance fingerprint images in Fourier domain based on block.But there are some shortcomings in these works,they are not robust enough to non-smooth areas,and the size of the window is not easy to determine.A curved- regions-based fingerprint enhancement algorithm in Fourier domain is proposed to solve these problems.Curved-region transform,which finds curved region and map to 2-D array,is used in Fourier domain,and filters are designed based on the frequency images of curved regions.Fingerprint image is partitioned into smooth areas or non-smooth areas,and only construct curved regions in non-smooth areas in order to improve the execution efficiency.Composite window is introduced to resolve the choice of window size.Experimental result shows that the improved method has better enhancement effect than the algorithms based on block.The matching accuracy of enhanced fingerprints can reach 99.74%.At the same time,the running time is significantly lower than that of the surface Gabor algorithm.

Key words: fingerprint, Fourier transformation, surface transformation, filter, fingerprint enhancement

中图分类号: 

• TP391