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Lnmm o qpp, Af a f – Ocean Optics OOIColor User Manual

Page 13

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10

The tristimulus values (X, Y and Z) are computed by the following equations. It is important to
note that by convention, these calculations are scaled so that the Y value for all illuminants is

100.00:

X

x

x

x

y

Y

y

y

y

y

Z

z

z

z

y

sam

ref

ref

ref

sam

ref

ref

ref

sam

ref

ref

ref

=

L

NMM

O

QPP

=

L

NMM

O

QPP

=

L

NMM

O

QPP

100

100

100

All other color space values are derived from these fundamental tristimulus values:

x

X

X

Y

Z

y

Y

X

Y

Z

z

Z

X

Y

Z

=

+ +

=

+ +

=

+ +

′ =

+

+

′ =

+

+

′ =

+

+

+

+

u

X

X

Y

Z

v

Y

X

Y

Z

w

X

Y

Z

X

Y

Z

4

15

3

9

15

3

3

6

3

15

3

u v

v

v

u

u

u v

u

u

v

v

,

atan

,

hue angle

Saturation

Illuminant

Illuminant

Illuminant

Illuminant

=

′ − ′
′ − ′

=

′ − ′
′ − ′

13

2

2

a

f

a

f

The derivation of other color space values can be found in references on measuring color. The

reference used for all of the coordinates and equations was R.W.G Hunt, Measuring Colour, 2

nd

Edition, Ellis Horwood, 1991.