If you are considering whether another light could reveal a scratch, start with a comparison plan.
Define the feature to find
Separate a clear overall photograph from an image suited to inspection. List scratches, contaminants or color differences individually. Where possible, include samples with different feature positions and sizes.
Record changed conditions
Record lighting position, target orientation and camera settings alongside the images. Change conditions in a way that lets you identify what changed the appearance. Compare feature-to-background contrast, rather than selecting only the brightest image.
Carry findings into the next comparison
Keep difficult examples as well as selected images. Note acceptable surface features that could be mistaken for defects and concerns about positioning. A conditions sheet paired with representative images helps guide the next test.
What to record
| Item | Record |
|---|---|
| Target | Material, finish, acceptable/defective status, feature of interest |
| Lighting | Type, direction, working distance, brightness settings |
| Camera and lens | Model, field of view, exposure, gain, aperture |
| Results | Image name, visible and difficult features, next change to try |
Use multi-angle illumination and the hybrid lighting examples to choose directions to test. For equipment planning, see imaging setup.
