A fast circle detection method based on threshold segmentation and validity check for FPC images

Flexible printed circuit board (FPC) is a popular substrate for packaging integrated circuits (ICs). Detecting the circles rapidly on FPCs by using computer vision is very important to assess the quality of FPCs during its manufacturing. In this paper, a fast circle detection approach based on a threshold segmentation method and a validation check is proposed. In the algorithm, the image is firstly segmented by an adaptive heuristic threshold to obtain closed contours; then circle candidates are obtained by eliminating obvious non-circle contours; and at last, circle candidates are further validated to be circles according to Helmholtz principle. Experimental results show that the proposed method is very fast and has high detection rates to detect the circles on FPC images.