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This interactive CIE 1931 Diagram requires Silverlight which is most likely already
installed on your computer.
Wikipedia has a good article
on CIE 1931 color space.
Moving the cursor in the diagram will show the CIE diagram coordinates (x, y, z)
and its corresponding (R, G, B) values in the upper-left panel.
Clicking the left mouse button places an arrow pointing to the clicked point, and
the upper-left CIE coordinates panel freezes the values. Clicking the left mouse
button again removes the arrow, and the CIE coordinates values will follow the cursor
Lower-left panel displays monochromatic light information. The monochromatic light
wavelength can be changed by using the wavelength slider.
If "Show monochromatic mark" is checked, a dot corresponding to the selected
monochromatic light wavelength will be displayed along the boundary of the diagram.
If "No added white" is checked, only the triangle region which color can
be truly rendered by a standard monitor is displayed. Any point of the CIE diagram
outside this region has at least one of the (R, G, B) being negative. When "No
added white" is not checked, the color of each of these points is rendered
by adding white color (i.e. increaseing R, G and B in the same amount) until no
more negative values among (R, G, B).
CIE chromaticity diagram is a 2-D diagram in a 3-D (xyz) space, so the best way
to present it is to draw it in the 3-D xyz space and allow it to be looked at from
different angle. Biyee has a limited version of 3D CIE 1931
Diagram (Java 3D needs to be installed).
Since it is impossible for a color monitor with RGB phosphors to display the full
spectrum of colors of a true CIE diagram, the part that has negative R, G, or B
values are displayed by adding white to them until the most negative value is raised
The following table lists different variants CIE 1931 chromaticity diagram
||Three simple 2-D CIE 1931 diagrams
Diagram w/o added white
||Three diagrams with negative R, G, B values replaced with zero
by adding white to
the entire diagram.
||Three diagrams that do not show the part that cannot be reproduced
These diagrams are based on 1931 2-degree CIE xyz color matching functions that remain
international standards in both colorimetry and photometry. International
Telecommunication Union uses 1931 CIE color matching functions in their recommendations
for worldwide unified colorimetry (ITU-RBT.709-4, ITU-R BT.1361). Most color monitors comply
with the standard. This makes it possible to display 1931 CIE diagrams correctly
on different color monitors.
There are other color coordinate systems most of which are not any kind of
transform of 1931 CIE system, so it is impossible to display diagrams of those system
correctly on different monitors that are calibrated with 1931 CIE system.