X - R i t e e X a c t ™ I n s t r u m e n t
37
Hue Error and Grayness Function
Hue Error indicates the variation of a printed color from a theoretical pure color. Grayness
indicates the presence of gray in a color that makes it appear less saturated. Hue Error and
Grayness are used to check for color consistency throughout a press run.
Hue error and grayness are calculated using the following formulas.
100
x
D
D
D
D
H
L
H
L
M
−
−
=
100
x
D
D
G
H
L
=
Where: D
H
= Highest density of C, M, or Y.
D
M
= 2nd highest density of C, M, or Y.
D
L
= Lowest density of C, M, or Y.
Hue Error and Grayness Measurement
Displays hue error and grayness with or without paper subtracted. Hue/Gray measures the
selected ink through all three filters (cyan, magenta, and yellow). Hue error and grayness values
are displayed along with color toward color: V (visual), C (cyan), M (magenta), and Y (yellow).
For example, C ->
Y indicates the color is cyan toward yellow.
1.
Select Hue Error & Grayness function.
2.
Measure paper if required.
3.
Measure solid patch.
4.
View data.
Colormetric Functions
CIE L*a*b*
This function is derived from the CIE 1931 XYZ color space in an effort to be perceptually uniform.
The L* dimension related to Lightness while a*(red/green) and b* (yellow/blue) are for color.
Perceptually uniform means that a change of the same amount in a color value should produce a
change of about the same visual importance. When a valid standard is present, the delta values
will be included along with the delta E type that is configured.
CIE L*C*h°
This function is a colorspace equivalent to CIEL*a*b*, the main difference is that in L*a*b* the
color values are plotted in a Cartesian coordinate system, while L*C*h° is polar coordinate
system. L* stays the same, but C* refers to chroma or strength which is the radius and h° is the
hue angle. When a valid standard is present, the delta values will be included along with the delta
E type that is configured.
Simulated color and timestamp of
reading displayed
Function, response, and
Measurement Condition selected
Hue error and grayness
values
Cyan towards Magenta
