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Category: painting

3rd part of D65 n°4 (again)

working…..

Note: the orange color in particular isn’t really rendered by digital photo/computer screen

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

Primaries again (D65 n°4)

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I still have to measure the colors I made from pure and mixed pigments here to be sure and more precise about that, but a priori I would estimate that about half of them are either badly rendered by the digital camera, or simply un-displayable on a standard computer screen (outside the sRGB gamut!)

The 41 colors I did so far are an attempt to get very close to ‘MacAdam’s limits,’ i.e., the best colors that can be made from pigments or other colored materials without ‘cheating’ with fluorescence (anyway fluo or ‘neon’ colors are fugitive, and another constraint of the colors made here is lightfastness… only highly lightfast pigments are used.)

Pigments are: Ultramarine Blue (Greenish,) 5 types of Phtalocyanines: Reddish-Blue, Cyan, Blue-Green and 2 Greens; Cadmium: Red, Red-Orange, Orange and 4 Yellow types; PR122 Sennelier & Lukas; Cobalt: Turquoise Brilliant & Dark, Pink; Lamp Black; Titanium & Zinc Whites.

Some colors might look like blacks while they are extremely saturated & dark colors (my darkest color is actually a Blue, not a Black! Its reflectance adds up to 2.6%!)

Next update I’ll clarify what’s possible to display on a screen (tomorrow probably.)

Bye ;)

a messy update about ‘primary colors’

It’s been weeks since I started to ‘expand’ my collection of ‘primary colors.’ I have around 50 of them now, and it’s not finished.

If you wonder what I call a ‘primary color’ here’s a definition: in my system, it is a color that cannot be made from others. For example, If I superimpose opaque blue and white lines, I get a light blue that is less saturated than a blue made from the actual mixture of the 2 pigments. So that mixture becomes a ‘primary color. From this perspective, there’s an infinity of primaries, but still much much less than non-primaries.

A guy called Joshua Horowitz, (see: http://web.mit.edu/joshuah/www/ ) helped me solving the problem of defining primaries by programming a code that automatically ‘excludes’ non-primaries, among other things …

‘Primary’ colors: mixtures of organic/inorganic color pigments

a list of primaries

The little proto-software also allows a 3-D visualization of my ‘colorspace’ in CIE XYZ mode:

3D XYZ colorspace, every line intersection is a primary color

More important, the software automatically ‘solves’ a list of colors by giving max. 4 primaries for each target color, a great gain of time & simplicity…

I am now ready to explore the entire colorspace…

(temporary) gamut of my pigment-colorspace, and below:

‘genetic code’ of the picture above (Yxy colorimetric coordinates, sets of 4 primaries, necessary amounts for color matching)

expanding the collection of colors (finally able to work a bit!)

I am expanding my color “gamut” by making “subtractive” pigment mixtures. Everything is “plotted” in a CIE u’v’ diagram (see below).

The blue dots are measured colors, the two red squares are very pure cadmium Reds, the green triangle and the light blue cross are my new best Blues (one being very very dark: 3% of light diffusion), the cross in the middle is the white point. The Orange dots represent the limits of the sRGB gamut – I’m getting very close!

I figured out that even my best mineral pigments can become better by “purification” using transparent organic pigments.

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

D65 #3 about to be finished

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View from the mezzanine in my studio.

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…

Planck’s blackbody colors (first layers)

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This is a new thing.

For the moment I just did the first 2 layers of paint (depending on the case, Titanium White + Ultramarine Blue, or: Titanium White + Cadmium Yellow light,) – there are 2 left.

In the squares will be the average color (50%/50%) of the color of my background and of the colors of the planckian balckbody locus with temperatures from 4000 K° to 9500 K° – as given by these (approximative) formulae in the CIE UCS 1960 color space:

I choose to make these samples with the same brightness as my backgound, so only the color difference is visible. None of them is neutral grey because I’m working with illuminant D65 (my “white point” is there…,) which is not located on the planckian locus, but slightly blue-grennisher (see below)

The locus in the CIE UCS 1960 color space (after wikipedia)

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.

hi-resolution pictures of the prototype

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Light ON/OFF, hi-resolution orthographic panorama made with Hugin.

For me, there’s not much difference between such a work (the prototype, made of laserprints on paper) and a “traditionnal painting.”

I’m really starting to think it’s just the same thing, like Richter includes amateur photography in the field of “painting.”

Light Transformer Prototype v.2

The prototype is finally finished!

So, to explain in a few words: 1-the amount of light projected by high-power spots on the wall has been measured. 2-an algorithm has been created to absorb the light using black over white laser-prints until the wall’s surface emits the same amount of light to the eyes of an observer situated in front of it. 3-The central part of this print has been cut and the same process remade a second time within the limits of this cut.

The impression produced is impossible to reproduce in photography, so the pictures there are just “documentation.” The impression is a bit like if the light was actually coming from “behind” the wall, like if the rectangle was a “window,” opening the wall, like in a dark corridor…

I’m really happy with it, I think it would be great to remake this much bigger the next time (and after developping the tools for it, I could make it much faster and more precisely…) I’m thinking of a “virtual corridor.” I’ve always been attracted by the idea of “remaking” the corridors of italian museums, where you walk slowly and stop at every painting on your sides. I could now make the painting of a corridor of paintings… :)

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NORMAL LIGHT

TRANSFORMED (EQUALIZED) LIGHT

D65 #3 1st “fake lamp”

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