Research And Implementation Of Enhancement Algorithm For Finger Vein Images

With the progress of the times and the development of society,people are increasingly demanding the safety performance for the biometric recognition technology,but at present,there is no biological feature that is perfect.Compared with other biological features,the finger vein has the advantages of easy collection and high safety performance,which has received extensive attention in recent years.At present,there are still some problems that need to be solved in the application of finger vein recognition technology,for example,the finger vein is affected by illumination,near-infrared band parameter setting and finger posture during the process of image acquisition,resulting in poor quality of the collected vein image.Therefore,how to remove the noise effectively in the finger vein image and enhance the finger vein details becomes an urgent problem to be solved.In response to this problem,three methods of finger vein image enhancement are studied in this paper.The main contents are as follows:Aiming at the problem of low image contrast and unclear vein detail caused by uneven illumination intensity,a finger vein enhancement method using bilateral filter based on a single-scale Retinex is studied.This method uses the bilateral filtering function to convolve with the original image to accurately estimate the background illumination of the bright and dark regions in the finger vein image,so that the problem of uneven illumination can be effectively overcome in the Retinex enhancement process.The experimental results show that the method can effectively eliminate the halo phenomenon and achieve the purpose of enhancing the vein detail,and the enhancement effect is superior to the traditional single-scale Retinex method.In order to solve the problem of more background noise in finger vein images,and Aiming at the problem that the single guided filter algorithm can not highlight the finger vein details when applied to finger vein enhancement,a finger vein enhancement method based on guided filter combined with anisotropic diffusion is studied.The method combines the guided filtering to establish a vein detail enhancement model,and then uses the anisotropic diffusion filter to smooth and denoise the enhanced image.The experimental results show that this method not only can effectively enhance the vein det ails but also has a more significant effect on the elimination of background noise.In order to solve the problem of excessive enhancement in the in the vein-dense area,a finger vein enhancement method based on Hessian matrix is studied.Firstly,the Gaussian filter second derivative is convolved with the original image to obtain the Hessian matrix of each pixel.And then,a multi-scale vein enhancement filter for detecting vein lines is established by analyzing the eigenvalues of Hessian matrix.Finally,the images enhanced by different scale factors are analyzed and fused.The experimental results show that the method can effectively enhance the vein details of various scales in the finger vein image and avoid excessive enhancement in the vein-dense area.