NOTE
•
The |ΔL| value refers to the absolute value of △L.
•
The weighted |ΔL| puts more emphasis on the color differences for light grays, where the K
value is lower than 50%. (
â–³L (Delta L)
on page 252)
• The Estimated black point |ΔL| metric is called an
estimation
because the darkest patch of the
target chart is not necessarily the darkest possible color. There could be CMYK values that
reproduce a darker tint. The output profile determines the real black point value.
• Refer to
Patches of the target chart
on page 248 to read the description of the patches.
â–³Ch (Delta Ch)
Metrics Description
Average ΔCh composite
grays
Average color difference in ΔCh between measured Lab values of the
composite grays on the color control strip and the Lab values of the
matching patches of the reference printing condition.
Maximum ΔCh compo-
site grays
Highest color difference in ΔCh between measured Lab values of the
composite grays on the color control strip and the Lab values of the
matching patches of the reference printing condition.
Average weighted ΔCh
composite grays
Average color difference in weighted ΔCh between measured Lab
values of the composite grays on the color control strip and the Lab
values of the matching patches of the reference printing condition.
Maximum weighted ΔCh
composite grays
Highest color difference in weighted ΔCh between measured Lab val-
ues of the composite grays on the color control strip and the Lab val-
ues of the matching patches of the reference printing condition.
NOTE
•
The weighted ΔCh puts more emphasis on the color differences between composite grays,
where C is lower than 50%. (
â–³Ch (Delta Ch)
on page 253)
• Refer to
Patches of the target chart
on page 248 to read the description of the patches.
Overview of color validation metrics
440
Chapter 15 - References
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