What a camera needs to see a water spot on a cosmetics carton
To see a water spot on a cosmetics carton, you have to see that ring edge. An even lightening is not a water spot. If you can't see it, change the light or the resolution first. Don't loosen the threshold first.
To see a water spot on a cosmetics carton, you have to see that ring edge. An even lightening is not a water spot. If you can't see it, change the light or the resolution first. Don't loosen the threshold first.
If you can't see it, fix the optics first
A local ring mark, mottled inside. If the image can't separate it at all, changing the threshold only paints the brand color of the cosmetics carton red. You have to see that ring edge. An even lightening is not a water spot.
Optics
| Need | Enough | Not enough |
|---|---|---|
| You have to see that ring edge. An even lightening is not a water spot. | A local ring mark, mottled inside. | Only a blurry circle left |
| About 3 pixels across | Shows steadily | It comes and goes, and you still log it as detectable |
| The brand color is in the field of view | The critical spot is seen | You only light the decorative edge |
Try it on a sample
- Confirm you can separate it in the image: A local ring mark, mottled inside.
- Count about how many pixels it covers.
- If you can't see it clearly, change the light or the focus. Don't change the threshold.
