Iris Image Acquisition Method Based On Bilateral Telecentric Lens

With the development of society and the improvement of technology, the requirement of the security identification technology is more and more high. Compared with other traditional techniques, biometric identification technology has obvious advantages, and the iris recognition technology has been gradually accepted by people with high security and reliability. In iris recognition technology, the high quality of iris image is the base of the post image processing and recognition matching, the complete information of the iris image can improve the otherness between different iris, improving the accuracy of the recognition system, and also conducive to analyse the details of the iris texture feature. In the process of iris image acquisition, there are several reasons caused the reduction in the quality of iris image, first of all, due to the effect of lens distortion and the parallax will cause blurring of iris image; second the reflection of light source will make the collected iris image generating spot, resulting in the local information of iris image is missing; another reason is the color of the collected iris more darke or the lens the depth of field is too small, will cause the iris texture is not clear. In view of these problems, this paper proposes a new method of iris image acquisition based on the bilateral telecentric lens.The system design is divided into three parts, firstly in order to solve the problem of the lens distortion and depth of field, this paper using the bilateral telecentric lens of BT2348, usingthe the special optical structure of bilateral telecentric lens and a wide depth of field to eliminate the influence of the lens, also matching four LED point light source and the camera of MV3000uc; Secondly for iris image information is incomplete. In this paper, using the image stitching and fusion technology to eliminate the local information loss of the iris image owing to the spot, and using the method based on threshold method and Hough transform to realize the localization of the iris edge, and the image registration is based on the feature based shape matching method, which is based on the similarity transformation, and the resample of the image is based on the method of bilinear interpolation, and fusion method is based on the weighted average method based on pixel level; finally, doing the feature extraction of iris image based on the change of the regional feature scale and the 2D Gabor wavelet, then doing the complete matching by Hamming distance and doing the test contrastly, which the same matching method is used to match the iris image of this paper with other databases, and testing the iris image quality by comparing the matching rate.In this paper, mainly studied on the method of the complete iris image acquisition, using special optical structure of the bilateral telecentric lens, and combined with the method of image stitching and fusion to get the information of the complete iris image. The experimental results show that the iris image of this paper is rich in texture, and the information is complete, and improving the recognition rate of the recognition system.