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.