摘要
研究糖尿病变,定期的眼底筛查清晰病变图像,是发现和治疗病变的重要手段。图像清晰度评价函数的选择是自动对焦技术的关键。为了保证对焦的精度,提出了以血管边缘的清晰度作为评价函数和粗精调焦相结合的自动对焦算法。利用边缘置信度的辅助检测能快速准确地提取出血管边缘,将血管边缘检测结果作为自动对焦的评价函数。在接近正焦区域使用该评价函数以降低计算复杂度进行仿真。结果表明,算法比传统的基于梯度和的评价函数具有更好的无偏性,在对焦精度、抗噪声方面具有突出的优点,图像清晰,为检测提供了参考依据。
Auto-focusing technique is an important method to improve the automation for fundus camera.It is a key to auto-focusing technique that selecting image sharpness evaluation function.In order to ensure the focusing accuracy,this paper proposes a new auto-focus algorithm,using the definition of retinal vessel edge as sharpness evaluation function and combining the rough search with the fine search.Through the edge confidence detection,the retinal vessel edge can be extracted fast and accurately.To enhance the computational efficiency,the proposed sharpness evaluation function is used only in the in-focus area.Experimental results show that the approach has a better unbiasedness than the traditional gradient-based evaluation function and it is reliable and accurate,and able to inhibit the effects of noise.
出处
《计算机仿真》
CSCD
北大核心
2011年第5期271-274,共4页
Computer Simulation
基金
国家自然科学基金专项基金项目科学仪器基础研究专项(60827002)
关键词
自动对焦
评价函数
血管边缘
边缘置信度
粗精调焦
Auto-focus
Evaluation function
Vessel edge
Edge confidence
Rough and fine search
