It seems most references showing a CIE Yxy diagram can be reduced to very few (one?) sources. If I wanted to construct the diagram myself from some published measurement values, how would I do it?
I'm assuming there is some parametric function
f(wavelength) giving a vector
(x, y) for each
f. But how would that function
f look like?
Actually I wanted to construct a CIE Luv* diagram, but when knowing the
(x, y) vectors for CIE Yxy, I could easily convert those to
(u*, v*), right?
Drawing the outline (spectral line) is one part of the problem. Another part of the problem is filling in the correct colors (I'm aware that no existing computer display device can actually present them): Is it OK to put the C white at its position and use Gouraud-Shaded Triangle Meshes to interpolate the area between two points on the spectral line and that white point (Example Image connecting 470nm with 500nm and with Illuminant C)? That seems to be OK.
In case it's OK, how would I fill the "non-spectral triangle" outlines by both ends of the spectral line and the white-point? Trying that I found out that the ends of the spectral line practically represent black, so the triangle came out much more black than purple, and opposed to all diagrams I've seen before, there's a discontinuity where the non-spectral colors are (Example Image)
As an experiment, I cut off the end of the spectrum to 435-645nm, and the transition from spectral to non-spectral colors is rather smooth then. (Example Image)
However when you use normalized data the dark colors become bright, and the brighter colors become darker. Effectively I realized that the "white point" actually is a gray point (several diagrams seem to have that wrong), and it seems that Illuminant C is the correct one, too , so this is my final version so far.