Shade and pattern grading of tiles
The tile is compared with a reference tile in a booth with diffuse lighting. Shade difference and discontinuities in the aligned pattern are evaluated; a conforming tile goes to its shade stack and a print-defective tile to a separate outlet.
Shade grade and pattern defect are added to the tile record. The PLC drives the diverter gates; conforming tiles go to grade stacks and a defective tile to the reject outlet.
- 01 Infeed
- 02 Colour image
- 03 Reference matching
- 04 Grading
- 05 Stacking
The tile enters the enclosed lighting booth.
- Colour difference
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- Print bands
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Scenes are illustrative simulations; they are not customer references or performance guarantees.
Need
Directional reflections in the glaze alter the measured colour. Tiles must be compared under the same lighting and alignment to distinguish natural pattern variation from print banding.
Solution approach
The booth excludes ambient light; diffuse panels reduce glaze glare. The calibrated colour-camera image is aligned with the reference tile; colour difference and linear pattern discontinuities are calculated separately to produce shade grade and defect decisions.
Process steps
- 01
Infeed
The tile enters the enclosed lighting booth.
- 02
Colour image
The top surface is captured under diffuse illumination.
- 03
Reference matching
The pattern is aligned with the reference and colour difference is calculated.
- 04
Grading
Shade grade and pattern defect are evaluated separately.
- 05
Stacking
Gates direct the tile to a grade stack or the reject outlet.
Related applications
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