基于椭圆拟合的瞳孔中心精确定位算法研究

Research on Exact Location Algorithm of Pupil Center Based on Ellipse Fitting

为了实现临床上精准视线跟踪的要求,提出了一种基于最小二乘法椭圆拟合的孔中心定位算法。首先在红外光源条件下,用摄像机捕获人眼图像,预处理后得到二值化图像,并提取图像轮廓,利用组成轮廓的像素点数100~300,对瞳孔进行粗过滤。对得到的系列轮廓随机选择6个点进行椭圆拟合,计算椭圆中心与边缘距离的方差,方差最小的为瞳孔中心。算法具有对存在白斑干扰及半闭眼状态时的瞳孔中心准确识别的优点。实验表明,该算法能够准确地定位瞳孔中心,且满足实时性要求。

In order to realize the requirement of precise eye tracking in clinical, a pupil center location algorithm based on the least square method is proposed. First, the eye image was captured by the camera under the infrared light, and then the two-valued image was obtained after preprocessing. Use the number of pixels that form the outline which was Extracting from the two-valued image to carry out the rough filtration of the pupil. The ellipse curve was fitting by the randomly select 6 pixels on the filtered contours, and then calculated the variance of distance between the center and the edge of the ellipse. The ellipse center is ellipse center, where the variance of the distance is Minimum. The algorithm has advantage of accurate identification the pupil center when there is white spot interference and squint. Experiments show that the pupil center can be located quickly and real-timely by this algorithm.