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## Tag: CIE

### D65 n°4, four solutions, 2013

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A study for new graphic solutions.

### another D65 n°4

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A lot of being human is about being stupid, and what happens then is failed works.

This is the ‘new’ or ‘real’ D65 n°4

### D65 n°1, details, 2011

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Very near “neutral grey”

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Equivalent optical average color samples

### D65 n°3, transparences / lampe / spectres, 2012

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Below, detail: desaturated daylight spectrum

### a new step: color with colors

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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,

$\vec{M} = a.\vec{A} + b.\vec{B} + c.\vec{C} + d.\vec{D}$

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:

$\begin{pmatrix} M_x \\ M_y \\ M_z \\ 1 \end{pmatrix} =
\begin{pmatrix} A_x & B_x & C_x & D_x \\ A_y & B_y & C_y & D_y \\ A_z & B_z & C_z & D_z \\ 1 & 1 & 1 & 1\end{pmatrix}
\times \begin{pmatrix} a \\ b \\ c \\ d \end{pmatrix}$

Then we solve this:

$\begin{pmatrix} a \\ b \\ c \\ d \end{pmatrix} = P \times \begin{pmatrix} M_x \\ M_y \\ M_z \\ 1 \end{pmatrix}$

with P being the inversion of our matrix:

$P = \begin{pmatrix} A_x & B_x & C_x & D_x \\ A_y & B_y & C_y & D_y \\ A_z & B_z & C_z & D_z \\ 1 & 1 & 1 & 1\end{pmatrix}^{-1}$

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…

### D65 n°3 part II starts

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I’m gonna do a “lamp simulation” (a circular gradient with constant tint and varying brightness, based on the abstract model of a “perfect lamp,”) based on 11 colors: 3 times RGB with 3 levels of brightness (I dont enter into the detail of how I choosed them) and Black/White.

### good & bad news :)

The bad news: the laser printer cannot handle large black prints, some unit of the printer makes a random glossy layer on it.

the random gloss

the (very) good news id that the luminance correction is not very angle-dependant, means that except for that random gloss, the correction works at a wide variety of viewpoints, that’s really nice.

from the left side, the gloss dissappears and the flat is still “flat.”

below: zooms on different parts from the left side (same shutter speed)

### uniformizer prototype

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Thanks to the measurement work and to a script made by Robert O., we were able to generate this first approximation of the wall luminance correction. This is a laserprint (printed in ABC Europe, Brussels) @ 400 DPI, 90 x 230 cm.

3 kinds of patterns were generated: lines, grids (crossed white lines,) and random squares.

We’ll check tomorrow if that works with the proper lighting.

:)

### wall to be visually uniformized: “ganzfeld” prototype

I will try to create a “ganzfeld” on this wall by subtracting light (using black printed patterns.)

This is the object of my residency at Netwerk, Aalst, BE, from last Monday to next Saturday.

More documents will come…

### D65 lighting prototype @ JVE, Maastricht – 2011

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D65 Normlicht light tubes mounted with an aluminium reflector

”Table-Tops Room,” Jan van Eyck Academie, Maastricht, NL, 2011

### D65 #3 1st “fake lamp”

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### D65 #3 sunlight picture

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I just came back from a long journey, the blog will be re-updated regularly soon.

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Thanks to a brief moment of sunlight here I could make a very clear picture.

I will be where they did this for 3 weeks ;)