a new step: color with colors

by adrien

CLICK! on the picture TO ZOOM!

Average colors of the Blackbody radiation colors (from 3500°K to 9500°K) and the color of the background. 50% of the paper is covered by paint. (This actually equals a desaturated picture of these colors, i.e. the mixture of blackbody colors and white D65 light at equal power)

Doing optical greys with colors might become history in my work, I start doing colors with colors – let me say something about my color system here:

I use colors following “Grassmann laws,” that means that I measure the lights coming from my pigments to your eyes, and by varying the proportions of these pigments I change the average color of the light that comes to you.

That works exactly in the same way as you computer’s screen except that I have more primary colors and usually less light.

Here, I used 7 “primaries”: Ultramarine Blue greenish extra, Cobalt Turkish light, a Green mixture of the former and of the next, Cadmium Yellow light, Cadmium Red “Cinnaber” shade and Titanium White (see below)

The “primaries” of my system (didn’t use the Cobalt Pink here yet!)

To create a color, I will make the average of 4 of these primaries, so a “possible” color will always be located in a “pyramidal space” with a primary color at each peak.

If I add the Black  primary, the main pyramids will be:

ReGrBlu-White and ReGrBlu-Black. Around them you’ll have ReGrYe-Whi/Bk ;  GrBluTu-W/Bk ;  ReBluPink-W/Bk

Which makes a total of 8 pyramids that touch each other and define the gamut of my system! (see below)

8 pyramids = gamut of 8 colors

The best solution to get the amounts a, b, c, d of the colors A,B,C,D  required to get a given color M is to use matrix calculus:

with: a+b+c+d=1,

the colors coordinates are in the CIE 1931 XYZ color space, so we create a square matrix with the color coordinates for each color, multiply by the solution, and equal it with the color we want:

Then we solve this:

with P being the inversion of our matrix:

That’s it!

Thank you very much PA5CAL from this forum to have helped out!

http://forums.futura-sciences.com/physique/555235-aide-cherche-equation-proportions-de-couleurs-moyennees.html

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Today could be a great day for painting: Georges Seurat’s dream-project of a “scientific painting” advanced a little. I’m sure he would be (very) happy to see this. I wish I had the email of the painter’s paradise, I would send this to him and all his friends…