摘要
以标准量块为实验对象,针对环形光源照射下的零件图像易出现倒角特征成像存在宽边缘,手动调焦缺乏相机聚焦的客观性而导致图像聚焦不精确等问题,提出一种基于改进梯度加权的零件图像高精度聚焦方法。首先采用条形光源45°布置的照射方式,消除倒角特征在成像中的宽边缘。其次,基于改进Otsu实现自适应分割阈值获取,提取图像特征边缘点。接着,基于4方向Sobel算子获取边缘点梯度值。然后,根据像素点与其8邻域像素点灰度分布差异值大小,获取像素点梯度加权系数。最后,通过改进梯度加权的聚焦评价函数完成图像清晰度评价,获取精确聚焦图像,实现高精度尺寸测量。实验结果表明,该方法相比传统高精度测量方法精度更高,与人工测量值相对误差在0.0024%以内。改进聚焦评价函数相比传统评价函数清晰度比率平均提升75倍,灵敏度因子平均提升5倍,陡峭度平均提升1倍。
Taking the standard gauge block as the experimental object,to address the problems that the chamfer features of the parts are prone to wide edges in the parts image under the illumination of ring light source,and the inaccurate image focusing is caused by manual focusing,which lacks the objectivity of camera focusing,etc.,a high-precision focusing method of parts image based on improved gradient weighting is proposed.Firstly,the illumination method of the strip light source arranged at a 45-degree angle is adopted to eliminate the wide edges of the chamfer features in the parts image.Secondly,the feature edge points of image are extracted by the adaptive segmentation threshold based on the improved Otsu.Then,the gradient values of edge pixels are obtained based on the 4-direction Sobel operator.Then,according to the grayscale distribution difference between the pixel and its 8 neighboring pixels,the gradient weighting coefficient of the pixel is obtained.Finally,the sharpness evaluation of image is completed by the improved function of gradient-weighted focus evaluation,thus,the accurate focus image is obtained and the high-precision measurement of size is realized.The experimental results show that the proposed method is more accurate than the traditional high-precision measurement method,and the relative error with the manual measurement is less than 0.0024%.The improved focus evaluation function in this paper is improved by 75 times in sharpness ratio,5 times in sensitivity factor and double in steepness on average compared with the traditional evaluation functions.
作者
曹震
巢渊
徐魏
杜帅帅
张敏
Cao Zhen;Chao Yuan;Xu Wei;Du Shuaishuai;Zhang Min(School of Mechanical Engineering,Jiangsu University of Technology,Changzhou 213001,China;College of Internet of Things Engineering,Hohai University,Changzhou 213022,China;Changzhou Xiangming Intelligent Drive System Corporation,Changzhou 213011,China)
出处
《电子测量与仪器学报》
CSCD
北大核心
2023年第11期132-142,共11页
Journal of Electronic Measurement and Instrumentation
基金
国家自然科学基金(51905235)
江苏省自然科学基金(BK20191037)项目资助
关键词
自动聚焦
清晰度评价
光源优化
梯度加权
视觉测量
auto-focus
articulation evaluation
light source optimization
gradient weighting
vision measurement
作者简介
曹震,2018年于南京信息工程大学滨江学院获得学士学位,现为江苏理工学院硕士研究生,主要研究方向为机电产品检测与智能控制。E-mail:cz_albert@163.com;通信作者:巢渊,2011年于东南大学获得学士学位,2017年于东南大学获得博士学位,现为江苏理工学院副教授、硕士生导师,主要研究方向为机器视觉测量与检测、机电一体化装备智能控制技术。E-mail:chaoyuan@jsut.edu.cn
