Automatic illumination adjustment for visual inspection device using spectrum analysis

In the visual inspection automated by the image processing, the importance of the machine vision lighting technology have recently drawn attention among the users of the visual inspection device. The machine vision lighting technology provides methods of the selection and the adjustment of illuminations for the visual inspection appropriately. However, it is difficult for the users to study the machine vision lighting technology because it needs the knowledge and the experience. Moreover, a defective product has several defective features appeared or disappeared with the angle and the color. This paper proposes the system to adjust parameters of the illumination for the visual inspection. A non-defective product is captured by this system with modifying four parameters: light quantity of red, green and blue LEDs, and the angle of LEDs. Further, the appropriate parameters of the illumination are decided by the spectrum analysis used for the image quality evaluation. In the step of evaluation, three type of defective/non-defective products are used to evaluation. Parameters of the illumination are decided by our system using the non-defective product. All of appearance of defective-features are confirmed by the visual observation and binarizing images in all type of products using this evaluation.