A colour validation test has a series of metrics that are calculated and evaluated when the test is performed.
The tables lists all metrics that can be used in a colour validation test. In practice, a colour validation test uses a small subset of the available metrics.
The measurements are the measured Lab values of the patches of the printed target chart of the test.
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Metrics |
Description |
|---|---|
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Substrate ΔE00 |
Colour difference in ΔE00 between the measured and the reference substrate white. For a side-by-side evaluation, the colour control strip must be printed with the rendering intent absolute colorimetric. The reference substrate white is compared to the measured simulated substrate white of the printed media. |
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Maximum ΔE00 |
Highest colour difference in ΔE00 between the measured Lab values of the colour patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Average ΔE00 |
Average colour difference in ΔE00 between the measured Lab values of the colour patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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95th percentile ΔE00 |
The 95th percentile ΔE00 colour difference between the measured Lab values of the colour patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. This means that 95% of all measured patches have ΔE00 colour differences smaller than or equal to the metric value. |
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Maximum ΔE00 CMYK solids |
Highest colour difference in ΔE00 between the measured Lab values of the CMYK solid patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum ΔE00 CMY solids |
Highest colour difference in ΔE00 between the measured Lab values of the CMY solid patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum ΔE00 RGB overprints |
Highest colour difference in ΔE00 between the measured Lab values of the RGB overprint patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
NOTE
Delta E 2000, △E00 is the industry standard.
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Metrics |
Description |
|---|---|
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Substrate ΔE76 |
Colour difference in ΔE76 between the measured and the reference substrate white. For a side-by-side evaluation, the colour control strip must be printed with the rendering intent absolute colorimetric. The reference substrate white is compared to the measured simulated substrate white of the printed media. |
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Maximum ΔE76 |
Highest colour difference in ΔE76 between the measured Lab values of the colour patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Average ΔE76 |
Average colour difference in ΔE76 between the measured Lab values of the colour patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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95th percentile ΔE76 |
The 95th percentile ΔE76 colour difference between the measured Lab values of the colour patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. This means that 95% of all measured patches have ΔE76 colour differences smaller than or equal to the metric value. |
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Maximum ΔE76 CMYK solids |
Highest colour difference in ΔE76 between the measured Lab values of the CMYK solid patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum ΔE76 CMY solids |
Highest colour difference in ΔE76 between the measured Lab values of the CMY solid patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum ΔE76 RGB overprints |
Highest colour difference in ΔE76 between the measured Lab values of the RGB overprint patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
NOTE
Delta E 1976, △E76 is based on a less complicated and accurate distance calculation.
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Metrics |
Description |
|---|---|
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Maximum ΔH CMYK solids |
Highest colour difference in ΔH between the measured Lab values of the CMYK solid patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum ΔH CMYK solids and RGB overprints |
Highest colour difference in ΔH between the measured Lab values of the CMYK solid patches and the RGB overprint patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum ΔH CMY solids and RGB overprints |
Highest colour difference in ΔH between the measured Lab values of the CMY solid patches and the RGB overprint patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum ΔH CMY solids |
Highest colour difference in ΔH between the measured Lab values of the CMY solid patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Average ΔH composite grays |
Average colour difference in ΔH between the measured Lab values of the composite grey patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum ΔH composite grays |
Highest colour difference in ΔH between the measured Lab values of the composite grey patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Metrics |
Description |
|---|---|
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Average |ΔL| composite grays |
Average lightness difference in |ΔL| between measured Lab values of the composite grey patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum |ΔL| composite grays |
Highest lightness difference in |ΔL| between measured Lab values of the composite grey patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Average weighted |ΔL| composite grays |
Average lightness difference in weighted |ΔL| between measured Lab values of the composite grey patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum weighted |ΔL| composite grays |
Highest lightness difference in weighted |ΔL| between measured Lab values of the composite grey patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Average |ΔL| K-only patches |
Average lightness difference in |ΔL| between measured Lab values of the K-only patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum |ΔL| K-only patches |
Highest lightness difference in |ΔL| between measured Lab values of the K-only patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Average weighted |ΔL| K-only patches |
Average lightness difference in weighted |ΔL| between measured Lab values of the K-only patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum weighted |ΔL| K-only patches |
Highest lightness difference in weighted |ΔL| between measured Lab values of the K-only patches on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Estimated black point |ΔL| |
Lightness difference in |ΔL| between the measured darkest patch on the colour control strip and the darkest patch of the reference printing condition. The darkest patch is the patch that has the lowest L* value. |
NOTE
The |ΔL| value refers to the absolute value of △L.
The weighted |ΔL| puts more emphasis on the colour differences for light greys, where the K value is lower than 50%.
The Estimated black point |ΔL| metric is called an estimation because the darkest patch of the target chart is not necessarily the darkest possible colour. There could be CMYK values that reproduce a darker tint. The output profile determines the real black point value.
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Metrics |
Description |
|---|---|
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Average ΔCh composite grays |
Average colour difference in ΔCh between measured Lab values of the composite greys on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum ΔCh composite grays |
Highest colour difference in ΔCh between measured Lab values of the composite greys on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Average weighted ΔCh composite grays |
Average colour difference in weighted ΔCh between measured Lab values of the composite greys on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
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Maximum weighted ΔCh composite grays |
Highest colour difference in weighted ΔCh between measured Lab values of the composite greys on the colour control strip and the Lab values of the matching patches of the reference printing condition. |
NOTE
The weighted ΔCh puts more emphasis on the colour differences between composite greys, where C is lower than 50%.