虹膜环状线条是虹膜特定纹理形状之一.针对于环状线条具有弱信号性、边缘不清晰、采用常规的边缘检测方法非常容易漏检和误检的问题,提出了一种新的虹膜预处理方法来提高检出率,降低误检率.定位瞳孔圆心与半径,得到包含有环状线条的感兴趣区域(ROI).由于环状线条在整体上具备线状的特征,在截面灰度分布上符合高斯曲线的分布特征,设计与环状线条相似的改进二维匹配滤波器增强环状线条的信号强度,提高信噪比.将预处理后的虹膜图像与直接采用Canny算子检测的图像进行实验对比,检出率有了较大的提高,同时降低了误检率.%Iris circular line is one of the specific shape iris textures.To solve the problem that circular line signal is weak and the edge is not clear,and the conventional edge detection method is very easy to missed and false detection,this paper proposed a new iris preprocessed method.Firstly,it localizationed the pupil center coordinate and radius,and obtained ROI that contained a circular line.Since the circular line had the linear characteristics in the whole,and the distribution of the cross section was similar to the Gauss curve in the distribution characteristics,then it designed a two-dimensional matched filter to enhance the signal strength of circular lines,which improved signal to noise ratio.The experimental results after the preprocessing the iris image compared with directly using Canny operator,the detection rate has been not only greatly improved,but also reduces the false detection rate.
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