Visual inspection is the image-based inspection of parts where a camera scans the part under test for both failures and quality defects. Automated inspection and defect detection are critical for high-throughput quality control in production systems. Visual inspection systems with high-resolution cameras efficiently detect microscale or even nanoscale defects that are difficult for human eyes to pick up. Hence, they are widely adopted in many industries for detection of flaws on manufactured surfaces such as metallic rails, semiconductor wafers, and contact lenses.