Chapter 3
– Theory of Operation
16
CIE XYZ Tristimulus and Photometric Values
Once the three Tristimulus values (X, Y, Z) have been derived, useful colorimetric values such as CIE
1931 x, y and CIE 1976 u’, v’ can be calculated by the following formulae:
CIE 1931 x, y
Z
Y
X
X
x
+
+
=
Z
Y
X
Y
y
+
+
=
CIE 1976 u’, v’
(
)
Z
Y
X
X
u
3
15
/
4
'
+
+
=
(
)
Z
Y
X
Y
v
3
15
/
9
'
+
+
=
Where:
X, Y, and Z are the three CIE Tristimulus values. X represents
the red component, Y is the green component and Z is the blue
component.
Y also serves as the photometric value
– when using the standard
MS-75 lens, Y gives candelas / meter² - the SI unit for luminance.
To find footlamberts (English unit of luminance), multiply cd/m² by
0.2919.
683 is a constant used to convert lumens to watts. There are 683
lumens per watt at 555 nm for photopic (daylight) vision.
S(
) = the corrected spectral data,
( ) ( ) ( )
Z
Y
X
,
,
are the three
CIE Tristimulus functions (curves) and
(
) is the data increment
1.0 for the A-TAK V-7HS.
( ) ( ) ( )
=
780
380
683
X
S
X
( ) ( ) ( )
=
780
380
683
Y
S
Y
( ) ( ) ( )
=
780
380
683
Z
S
Z
Summary of Contents for PHOTO RESEARCH A-TAKT V-7HS
Page 2: ......
Page 11: ...Chapter 2 System Overview 7...
Page 18: ...Chapter 3 Theory of Operation 14...
Page 47: ...43 FIGURE 13 A TKT V 7HS ENVELOPE DRAWING Front Mounting Hole...
