角膜地形图仪中实时图像检测

为实现角膜地形图仪中实时图像检测, 找到一种图像清晰度评价函数对实时角膜图像进行快速、稳定、精确的判别至关重要。基于角膜地形图仪中光学成像系统, 分析系统离焦对图像清晰度的影响, 并提出一种关于图像清晰度的评价方法。该方法选择拉普拉斯函数作为全局图像粗调的评判参数, 通过霍夫圆变换及亚像素边缘检测来确定图像的中心点, 并采用Sobel算子与Canny算子相结合的边缘检测方法根据中心点找出最清晰边缘, 从而实时获得最清晰的角膜图像。实验表明, 该方法具有很好的稳定性和抗噪性, 能够准确、有效地评价角膜图像的清晰度, 可用于角膜地形图仪中实时图像的精准检测。

Abstract

In order to realize real-time image detection in corneal topography, it is a key step to find an image sharpness evaluation function for fast, stable and accurate identification of real-time corneal images. For the optical imaging system of corneal topography, the defocusing effect on image sharpness is analyzed and a new image sharpness evaluation method is proposed. In the method, the Laplace function is selected as the coarse tuning evaluation parameter of a global image. Through Hough circle transform and sub-pixel edge detection, the center of the image is determined. With the center of the image, the clearest edge is found by the edge detection method based on the combination of Sobel operator and Canny operator. Based on that, the clearest corneal image is got in real-time. The experimental results verify that the proposed method has good stability and noise immunity, can evaluate the image sharpness accurately and effectively, and is suitable for real-time image detection in corneal topography.

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