What a camera needs to see scumming on a food web
The light ink needs enough contrast. Overexposure hides it. A steady view needs about 3 pixels. If it is not clear, do not loosen the threshold.
To see scumming on a food web, the light ink needs enough contrast. Overexposure hides it. 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
There is a light film of ink where there should be none. If the picture cannot separate it at all, moving the threshold only paints the ingredient list and the heat-seal area of the food web red. The light ink needs enough contrast. Overexposure hides it.
Optics
| What is needed | What enough looks like | What not enough looks like |
|---|---|---|
| The light ink needs enough contrast. Overexposure hides it | A light film of ink sits where there should be none | Only a blurry circle is left |
| It spans about 3 pixels | It shows steadily | It comes and goes, yet it is written down as detectable |
| The ingredient list and the heat-seal area are in the field of view | The critical place is seen | Only the decorative edge is lit |
Try it on a sample
- See whether the picture separates it: a light film of ink sits where there should be none.
- Count about how many pixels it covers.
- If it is not clear, change the light or the focus, not the threshold.
