曲线拟合的虹膜定位算法研究

虹膜定位是在虹膜图像中找到虹膜的内外边界，它是虹膜识别中的重要环节。该文提出了一种根据曲线拟合来进行虹膜快速定位的新方法，即先对图像进行分块并提取包含瞳孔的子图像块；再结合类间方差法提取瞳孔的二值化阈值，确定虹膜内边界点；然后根据关键的感兴趣区域灰度梯度信息确定虹膜外边界点；最后对内外边界点采用最小二乘法原理来进行曲线拟合，从而确定虹膜内外边界。通过实验表明该文提出的算法能快速准确地定位虹膜内外边界。

Improved Iris Location Algorithm Based on Curve Fitting

Iris location, an important link in iris recognition, is to detect inner and outer boundaries of iris in an iris image, In the paper, an improved algorithm is proposed to locate iris by means of curve fitting. In this algorithm, an iris image is blocked firstly and its sub-image blocks which cover pupil are extracted. Next, a binary threshold of pupil is set by means of the method of maximum variance between clusters, and the inner-boundary-points of iris are determined. And then, the outer-boundary-points of iris are gotten on the basis of gray gradient of key regions of interest. Consequently, some characteristic pixels in regions of interest are selected respectively and inner and outer boundaries of iris are fitted according to principles of least squares. The results of experiment show that the proposed algorithm can locate iris accurately and quickly.