HunterLab EasyMatch QC, Руководство пользователя

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EasyMatch QC User’s Manual Version 2.1
Measurement Values A-7
Other Color Difference Scales
Elliptical Tolerancing Scales (CMC, CIE94, DIN99, and CIE00)
CMC
The equation for dE CMC describes an ellipsoidal volume with axes in the direction of lightness (l),
chroma (c), and hue (h) centered about a standard. When the semi-axis lengths for the dE CMC formula
equal the calculated lSL, cSC, and SH values for the standard, the resulting ellipsoid describes a 1.0 dE
CMC unit volume/tolerance. This volume and the size of its component parts become the basis for the
establishment of an appropriately sized volume of acceptability for a given commercial situation by the
application of a commercial factor (cf). The cf is the dE CMC tolerance.
When l = 2.0 and c = 1.0, the equation fixes the ratio of the three components (SL:SC:SH) to correlate
with visible assessment of typical textile samples. Other values of l may be required in cases where the
surface characteristics change dramatically. The value of c is always left at 1.0.
2 2 2
SH
* dH
+
cSC
* dC
+
lSL
* dL
= cf CMC dE


















=
Absolute
lSL
* dL
= CMC dL
cSC
* dC
= CMC dC
SH
* dH
= CMC dH
where
L*, C*, and H* are those of the standard unless otherwise specified.
CMC ratio l:c. This ratio is generally 1:1 for coatings, 1.3:1 for plastics, and 2:1 for textiles. The l
value may be set anywhere between 0 and 5. The l:c ratio determines the shape of the ellipsoid.
commercial factor cf. This value is usually one to represent a just-perceptible difference, but this value
may be adjusted for the industry and the product. This value may be set anywhere between 0.10 and
9.99. The commercial factor determines the size of the ellipsoid.
* 0.01765L + 1
* 0.040975L
= SL
for L* ≥ 16
SL = 0.511 for L* < 16
SC =
0.0638C *
+ 0.0131C *
+ 0.638
1