A Fast and Precise Location Algorithm Research for the Pupil Center and the Corneal Reflection Spot Center
Yu Luo1 , Liu Hongying1,2*, Xu Shuai1, Cai Jinzhi1, Pi Xitian1#
1School of Biomedical Engineering,Chongqing University,Chongqing 400030,China; 2Chongqing Medical Electronic Engineering Technology Research Center,Chongqing 400030,China
Abstract：The eye tracking system plays an important role in clinical medicine, in order to raise the recognition rate of the eye characteristic value in the system. A double filtration algorithm is innovatively proposed to locate the center of pupil and the center of corneal reflection in this paper. First, the acquired eyes image was processed by the pupil center location algorithm to reach binarization, and then the contour points with 100～300 was set as the threshold. Next, pupil contour was ellipse fitted using the least square ellipse fitting method, and the contour that was most close to the circle was used as the pupil contour to obtain pupil center. On this basis, the edge of the eye image in the certain range of the pupil center was detected, and then the external rectangular center of the contour was calculated. Taking the center of the pupil as the starting point for coordinate transformation, the corneal reflection spot center after converting coordinates was eventually calculated. This algorithm not only reduced the area of image processing to a certain extent, but also improvedthe processing speed and the recognition rate of reflection spot. The experimental results showed that the designed algorithm accurately located the pupil center and corneal reflex center in different conditions in real time. The maximum mean square deviation of pupil-corneal reflection vector was less than 0.74 pixels, and the average error was less than 0.53 pixels. The algorithm run at a speed of 12.8 ms/frame. The algorithm met the precision as well as showed very strong robustness, being of significance for the development of eye tracker.
余罗,刘洪英,许帅,蔡金芷,皮喜田. 一种快速精确的瞳孔和角膜反射光斑中心定位算法的研究[J]. 中国生物医学工程学报, 2017, 36(4): 434-441.
Yu Luo, Liu Hongying, Xu Shuai, Cai Jinzhi, Pi Xitian. A Fast and Precise Location Algorithm Research for the Pupil Center and the Corneal Reflection Spot Center. Chinese Journal of Biomedical Engineering, 2017, 36(4): 434-441.
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