Usability of Digital Cameras for Verifying Physically Based ...
Usability of Digital Cameras for Verifying Physically Based ...
Usability of Digital Cameras for Verifying Physically Based ...
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Figure 20: The CIE 1931 chromaticity diagram showing the wavelengths <strong>of</strong> light<br />
and the xy coordinates [cie06b].<br />
L ∗ �<br />
Y<br />
= 116<br />
a ∗ = 500<br />
b ∗ = 200<br />
Yn<br />
� � X<br />
� 1<br />
3<br />
− 16<br />
Xn<br />
� � Y<br />
Yn<br />
� 1<br />
3<br />
�<br />
Y<br />
−<br />
Yn<br />
� 1<br />
3<br />
�<br />
Z<br />
−<br />
Zn<br />
� � 1<br />
3<br />
where Xn, Yn and Zn are the tristimulus values <strong>of</strong> the reference white. For small<br />
values <strong>of</strong> V , V ∈ {X, Y, Z}, the normal <strong>for</strong>mulae are replaced by the following<br />
Vn<br />
modified <strong>for</strong>mulae:<br />
34<br />
� 1<br />
3<br />
�