Explainer · Inspection technology
What changes in camera inspection when the eggs are white?
Vigiovo's default thresholds were set for brown and cream eggs. A white shell has low saturation, and a bluish shell falls outside the warm hue range of the mask, so both need recalibration of hue and saturation. Before production, calibrate with eggs of the same colour under the same light, and confirm that the whole shell falls inside the mask.
Updated · 4 min read
Why does shell colour change the inspection?
Shell colour changes the values the camera measures, and Vigiovo's thresholds depend on those values. The default was set for brown or red and cream eggs, so a shell of another colour does not fit it without adjustment.
This applies to the mask, which separates the shell from the conveyor, and also to the stain measurement, which compares each region with the egg's own shell. If the mask is wrong, the dirt and crack measurements start from a wrong base. The steps are described in how Vigiovo grades eggs.
What happens to a white or bluish egg in the colour mask?
The shell mask accepts pixels with a warm hue, from red to yellow, saturation of at least 45 and brightness of at least 120, on a scale of 0 to 255. A white shell has low saturation, and a bluish shell has a hue outside the warm range. In both cases, the shell may not fall fully inside the mask.
The table summarises what to check for each shell colour:
| Shell type | Why it matters | What to check |
|---|---|---|
| Brown or cream | Warm hue and high saturation, within the default | Confirm that the whole shell falls inside the mask |
| White | Low saturation, which can drop below 45 | Confirm that the shell is not cut out |
| Bluish or greenish | Hue outside the range from red to yellow | Recalibrate the hue before production |
How do you recalibrate the mask for white shells?
Recalibrate hue and saturation with eggs of the same colour you will process, under the same lighting. Then adjust the dirt and crack thresholds, in that order:
- Gather white eggs from your production and review each one's class by hand.
- Pass the eggs under the camera with the production lighting, without changing the setup.
- Check in the annotated image whether the whole shell falls inside the mask, without cut-outs.
- Adjust hue and saturation until the shell is whole inside the mask and the belt is outside it.
- Then recalibrate the dirt and crack thresholds with the same sample.
- Record the new values and the date, and repeat the test after a change of bird strain or lighting.
The full process of sampling and review is in calibrating with labelled eggs.
Can the belt colour interfere with the mask?
Yes. The mask separates the shell from the rollers by hue and brightness. If the belt is close in colour to the shell, part of the belt can enter the mask, and that shifts the colour segmentation.
A white shell on grey rollers tends to contrast well, but a light shell on a light belt loses contrast. Choose a belt that contrasts with the shells you process, preferably dark and matte, and test with each egg colour.
What should you do when the line processes white and brown eggs together?
Calibrate with both colours and test the mask with both shell types. A setting that suits one colour can fail on the other, and that has to show up in the calibration, not in production.
The shell colour does not change what a surface camera sees. The interior of the egg stays out of reach, and candling remains the check for the interior, for white and brown eggs alike.
Frequently asked questions
Do I need a different camera to inspect white eggs?
- Usually not. What changes is the calibration of hue and saturation, along with the lighting and the belt colour, which must be redone for the shell of your production. Confirm with a sample before returning to production.
Can I use the brown egg calibration for white eggs?
- Not without testing. The hue and saturation thresholds were set for warm shells, and a white or bluish shell can fall outside them. Run the check with white eggs from your production before trusting the result.
How do you know whether the mask picked up the whole shell?
- Check the annotated image of a sample of each colour. If the shell looks cut out, with holes or with part of the egg outside, the mask needs hue or saturation adjustment before the dirt calibration.
Sources
- Como o Vigiovo classifica ovos sem IA / How Vigiovo grades eggs without AI, Vigiovo
- Changing Colorspaces, OpenCV documentation
How Vigiovo helps
Vigiovo grades eggs on the conveyor as clean, dirty, cracked or unverified, in real time, with deterministic computer vision: every decision comes with the measurements behind it, on an ordinary CPU.