Detecting product surface flaws—such as discolorations, burns, cracks, and scratches—is a difficult task for human or machine vision. These defects can have random shapes and low contrast, and are often obscured by the product’s natural surface texture or pattern. Detecting these defects with machine vision requires knowing what the defects can look like, careful attention to lighting, camera resolution and part presentation, and sophisticated machine vision algorithms.
Here we discuss cracks and scratches, which have rapid intensity changes that produce high spatial frequencies.