Lens inspection system using LoG and multi-level thresholds

An automatic defect detection system for the micro lens of a cellular phone was studied We presented a defect detection method using LoG filter and multiple level thresholds. We could find general defects such as scratch and even the stain defects that the detection might be difficult because of the low contrast between its background and a defect in the lens images. We did experiment using 50 spherical lens images with defects. As the experimental results, it showed the average recall and precision are about 92% 77% respectively in the case of sigma=2.5.