Granule / masterbatch colour analysis
The granule stream on a sample belt is imaged by a colour camera under the diffuse light of a dome. The mean colour of the measurement window is compared with the reference in L*a*b* space, and the colour difference (ΔE) is tracked as a trend.
Illustrative colour difference and trend are monitored on the operator display. A batch outside the tolerance window is flagged and the stack light alarms; the sample continues into the collection crate.
- 01 Sample flow
- 02 Acquire
- 03 Colour
- 04 Trend
- 05 Decide
A granule sample drawn from production flows as a thin bed on the belt.
- Colour diff. ΔE
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- ΔL*
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- Δa*
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Scenes are illustrative simulations; they are not customer references or performance guarantees.
Need
Directional reflections on glossy pellets and shadows between them alter the mean colour. Batch colour drift must be distinguished from natural pellet variation.
Solution approach
Dome lighting diffusely illuminates the thin sample bed while an overhead camera observes a reference chip and pellet window. Samples are compared in L*a*b* space; the raw pellet image, reference/measured colours and illustrative ΔE trend are displayed together.
Process steps
- 01
Sample flow
A granule sample drawn from production flows as a thin bed on the belt.
- 02
Acquire
The dome light strobes; a colour image is taken with reduced glare on glossy pellets.
- 03
Colour
The mean colour in the window is converted to L*a*b* and its difference to the reference is computed.
- 04
Trend
The ΔE of each shot is added to the chart and watched against the tolerance line.
- 05
Decide
The colour drift is evaluated against the tolerance line.
Related applications
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