This lists the set of tests on color patches in the [Patches] tab to perform after measurement of the swatch during the process of swatch validation. All the tests in the list need to succeed in order for the swatch being defined to pass validation (Figure 5).
TIP: A test is a comparison operation that is performed on one or more patches from the patches tab. A test succeeds if the comparison is less than or equal to the threshold associated with the test.
There are [Add…], [Edit…], and [Delete] buttons in this tab.
Add - You can add a test to be performed during swatch validation by clicking this button (Figure 6).
Each test has a minimum threshold (value and precision) that must be achieved for conformance purposes on the subset of patches. Thresholds are used to establish acceptability of printed output taking into consideration a number of different factors including (but not limited to):
- Noticeability of color difference
- Variability in the printing process
- Variability in the measurement process
Edit – Click this button when you want to edit a desired patch. The UI to edit a patch is the same to add one (Figure 6).
The following tests can be used to compare measurements of patches in a swatch to previous Baseline measurements for purposes of validation:
- Mean DeltaE - This is used to determine whether the average color difference (defined using CIEDE2000) is below a given threshold.
- In general a DeltaE of less than 2.0 is not physically discernable
- Max DeltaE - This is usedto define the limit for the worst case color difference for the group of patches associated with the test.
- This value should generally be larger than a threshold for a Mean DeltaE
- Max DeltaE should be used to specify the threshold for a single color patch
- Percentile DeltaE - A Percentile DeltaE is used to define the limit for a percentage of the patches associated with the test that have a color difference less than or equal to the threshold.
- When Percentile DeltaE is selected, you must define the percentile of patches to use.
Tip: Using 95% is equivalent to saying "for the most part" or (95% of the time) the maximum color difference is less than or equal to the threshold.
(NOTE: Generally Percentile DeltaE is better to use than Max DeltaE with a large number of patches).
- Mean DeltaH / Max DeltaH - This is used to determine the average / maximum hue variation (independent of lightness and chroma differences). Max DeltaH is something that is generally used against single ink color solids to determine stability/acceptability of the ink.
- Mean DeltaC / Max DeltaC - This is used to determine the average / maximum color shift independent of differences in lightness. Generally used to asses the neutrality of near neutral colors.
- Mean DeltaL / Max DeltaL - This is used to determine the average / maximum shift in lightness.
When a test is created you select the patches that you want to operate on and provide a name for the group of patches (like "Solids" or "Customer Colors").
TIP 1: The filter provides a convenient mechanism to quickly find colors that have specific values for inclusion in the group of patches to associate with a test. (For instance, typing in 100 for the filter shows all the patches that have at least one ink channel that have 100% ink.)
TIP 2: The following tests and thresholds (Based on ISO 12647-7) for groups are defined for the Onyx Weekly Baseline:
Delete – Use this button when you want to delete desired test. This action cannot be undone.