What a camera needs to see an ink-skin spot on a food web
The spot must be solid. Defocus turns it into an ordinary round blot. If you cannot see it, change the light or the resolution first. Do not loosen the threshold first.
The spot must be solid. Defocus turns it into an ordinary round blot. If you cannot see it, change the light or the resolution first. Do not loosen the threshold first.
If you cannot see it, change the optics first
A solid dark spot that wipes or lifts off. If the picture cannot separate it at all, moving the threshold only paints the ingredient list and the heat-seal area on the food web as a field of red. The spot must be solid. Defocus turns it into an ordinary round blot.
Optics
| Needed | Enough looks like | Not enough looks like |
|---|---|---|
| The spot must be solid. Defocus turns it into an ordinary round blot. | A solid dark spot that wipes or lifts off. | Only a blurred circle left |
| About 3 pixels across | It shows steadily | It comes and goes, yet you write that it can be detected |
| The ingredient list and the heat-seal area are in the field of view | The critical place is seen | The light only hits the decoration edge |
Try it on a sample sheet
- Confirm the picture can separate this: A solid dark spot that wipes or lifts off.
- Count about how many pixels it covers.
- If you cannot see it clearly, change the light or the focus. Do not change the threshold.
