When sourcing visual inspection machines, the most critical factor is the imaging system resolution and camera type. High-precision industries require industrial-grade CCD or CMOS cameras with at least 5MP to 25MP resolution depending on the defect size. Additionally, evaluate the processing speed (frames per second) to ensure it matches your production line's throughput. The lighting system (e.g., ring lights, coaxial lights, or backlights) must be adjustable to eliminate shadows and highlights on different material surfaces like metal, glass, or plastic.