Research of Sub-Pixel Inner Diameter Measurement of Workpiece Based on OpenCV

A method of untouched measurement based on OpenCV is proposed to achieve the sub-pixel inner diameter Measurement of workpiece. Design and implement a visual measurement system on the inner diameter Measurement of workpiece. In the image, the grayscale of the noise and the aim is very close and very hard to be separated by the right threshold. To this difficult point, a method of two thresholds in two steps is proposed. First, remove the background noise with a smaller threshold; second, get the binarization image close to the real contour of the aim with a bigger threshold. The system deals with the image binarization, the interception of region of interest, contour extraction and so on, finally achieves the high-precision inner diameter measurement of workpiece. Repeat the measurement many times of the workpiece in different place in the field of view, the experimental results show that the consistency of the method is better than the HALCON machine vision software.