I place the x,y coordinates at ( 0.29, 0.3 ). The
line from the neutral point through this coordinate will cross the curve at a
dominant wavelength of 486 nanometers.
The Neutral Point is also the Illuminant Point
for the standard light source equivalent to daylight, and is the position of
any Gray Card illuminated by daylight. Now we know enough about the CIE
Color System to use it.
Find the x and y coordinates of the background
color of this page. Then use the diagram to determine the color's dominant
wavelength and calculate the excitation purity. I have marked
the positions of the Neutral Point and this pag'e background color with
Black Dots. I used a larger CIE chromacity diagram for the actual measurements.
I place the x,y coordinates at ( 0.29, 0.3 ). The
line from the neutral point through this coordinate will cross the curve at a
dominant wavelength of 486 nanometers.