85
Internal Calculation Processing
In this device, the following calculation processing is performed for data.
Chromaticity Coordinates
xy chromaticity coordinates of XYZ color coordinate system
u'v' chromaticity coordinates of UCS color coordinate system
Lightness Index
Y
: Tristimulus value Y in XYZ color coordinate system
Y
n
: Y value according to standard light on perfect reflecting diffuser
However, when is less than 0.008856, the following formula must be applied.
Chromaticness Index
CIE 1976 L
*
a
*
b
*
color coordinate system
X, Y, Z
: Tristimulus values in the XYZ color coordinate system
X
n
, Y
n
, Z
n
: Tristimulus values in the XYZ color coordinate system on a perfect reflecting
diffusier.
However, if , or have a value less than 0.008856, substitute the corresponding curbe
roots in the above formula with the values as shown below;
Z
Y
X
X
x
3Z
15Y
X
4X
u´
3Z
15Y
X
9Y
v´
16
3
1
n
Y
Y
116
*
L
0.008856
n
Y
Y
n
Y
Y
903.29
*
L
0.008856
≦
n
Y
Y
3
1
n
Y
Y
3
1
n
X
X
500
*
a
3
1
n
Z
Z
3
1
n
Y
Y
200
*
b
＞0.008856
n
Y
Y
＞0.008856
n
Z
Z
n
X
X
n
Y
Y
n
Z
Z
Z
Y
X
Y
y
＞0.008856
n
Ｘ
Ｘ
n
Y
Y
