Lighting selection and setup play a critical role in the success of a machine vision application. Vision systems rely on specific types of lighting to optimize contrast or to highlight a specific feature of interest. Developing an effective lighting system can be a difficult task, requiring the testing of multiple types of lights and cameras. Patterned area lighting (PAL) simplifies some of these difficult imaging problems on reflective, transparent or semitransparent materials by combining 2D and 3D qualitative methods into one image.
For years, detecting flaws on reflective surfaces and transparent objects has been difficult and costly, putting solutions out of reach for many users. When a defect has many variables, including size, direction and shape, making a positive identification becomes difficult. Vision systems only make decisions on what they were programed to evaluate on a very discrete set of rules or parameters. A difference between a scratch, scuff or other defect may be obvious to the trained eye of an inspector or quality engineer but becomes more challenging when seen through the lens of a discrete inspection system using machine vision. The goal of PAL lighting is to enhance these difficult-to-image flaws so machine vision software can evaluate them and make a decision.