机器视觉核桃分级中相机可变视场与像素转换系数自动获取方法

Variable View of Camera and Pixel Conversion Coefficient Getting Automatically in Machine Vision for Walnut Grading

针对利用机器视觉进行农产品无损检测中相机视场调节困难以及调整后需要重新标定的问题,提出一种基于MFC软件界面控制的大恒定焦USB 2.0工业相机视场自动调节方法,并通过试验对相机进行标定,拟合出相机高度和像素转换系数的关系式,当相机视场发生变化时,系统中超声波测高模块可以实时给出相机高度,程序根据关系式实时给出对应高度的像素转换系数,方便图像处理软件根据核桃轮廓像素数据换算出核桃尺寸,精确判断等级。

For machine vision post-agricultural non-destructive testing in the field of view camera adjustments are difficult and require re-cali-bration adjustment problems, this paper presented a constant USB 2.0 industrial camera of Daheng-Image company field of view of MFC soft-ware interface to control automatic adjustment method.And through experiments to calibrate the camera, the camera fitted the equation be-tween height and pixel conversion coefficient.When the camera field of view changed, ultrasound height measurement module in the system could give corresponding camera height.According to the equation, the program gave pixel conversion coefficient of corresponding height, which was convenient to image processing software.Walnut size was calculated according to the pixel count of walnut contour, so that the grade was accurately judged.