Rebelle 5 Pigments - Physical Color Mixing

It does look like real paint no?


Looks fantastic!
But unfortunately, they don’t tell how to achieve this. :zipper_mouth_face:


yes but keeping an watchful eye is always good. Also secrets don’t last forever.


This is really something else !!
Long back I had tried out a demo version of Artrage.
It’s physical colour mixing in thick paint mode,is also felt very good and …very real !

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I guess achieving MyPaint’s mixing might be easier since it’s already open source, so no secret:

Would be awesome if someone implemented it for Krita.

There is no awesome brush effects but they can be achieved in Krita already, I guess, maybe not 100% like in Rebelle or Artrage or Corel Painter, but quite good. So with that mixing it would be pretty nice, I think.

(The image above is just three colors, pure red, pure yellow and nearly pure blue, just darkened a bit). Green, orange and a bit of underwhelming purple (I’m sure you could get better results with a bit different colors though - I mean with traditional paints you can get ugly purple too) appeared on their own.


I agree.
I can manage the mixing part with more control with blenders.
But some special blenders are needed for watercolour and thick paint brushes.
I have used different custom made blenders available in various brush bundles.
No doubt,they are extremely good!
But still I feel like probably thick paint and watercolour need some special blenders.
Anyway,that’s my opinion…but right now,I am quite content with how much I have inside Krita :slight_smile: !

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No, you will never get green by mixing blue and yellow in Krita (for now). You’ll get an ugly grey color:

(sure you can make this circle look much better, but the it shows that you can get a nice purple and nice orange, but you won’t get green).

That’s because if you mix Red (100%), Green (100%), Blue (0) with Red(0), Green (0) and Blue (100%), you’ll get a color that is: (Red (x), Green (x), Blue (y)), but you need Red (0), Green (z), Blue (0). But to get that, you’d need x = 0 and y = 0 but at the same time x = z != 0. (Of course I made the numbers very exact and specific but even with small variances you see how it is). There must be a special mixing code. And that special mixing code is not easy to write.

Btw since you mention watercolors and oil paints, what is it that you specifically need for those blenders? Have you tried the brushes that use the color smudge engine with RGBA brush tips and lightness options in Krita 5.0 beta?

That Grey can grow to be so preetty though. (this is the ARD mix that is basically another RGB)

But I have been wanting to implement other methods to interpolate colors that would be a bit more similar to RL but it will be a bit esoteric and with a error. if you look at how paint mixes on the RGB you can see a weird pattern on them, a rule that I think that can be simplified.

My friend @urzeye is doing some tests. It seems that good results have been achieved. He is experimenting with oklab’s color mixing, gradients, filters, etc.
I hope better changes can be added to krita, but we don’t know the usage of gitlab yet.


That is so cool. The results look so nice and clean I really need to go at it again soon.

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I think it will be quite hard for me to explain my problem with words.
So it will be better to make a small example.
Right now I am concentrating more on RGBA thick paint brushes.
So my examples are made with RGBA bundle.
The kind of colour mixing effect (made with medibang) I am trying to achieve is also mentioned.
I hope I have managed to explain it properly.
Now I need to learn the trick how to achieve such mixing effects in Krita :slight_smile: .

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You can get green by mixing blue/cyan and yellow in Krita, you just have to change the blending mode. I know I’ve done tests before with subtractive mode, AND mode, and I think one or two others that worked to get that kind of mixing. Each mode had some sort of downside to it, though, such that I didn’t feel they worked quite like physical paint.

Unfortunately, in some quick testing I did just now, I wasn’t able to replicate those results with the smudge brush in lightness mode. In fact, with every mode I tried, the mixing looked like Normal mode, so I’m not sure it’s actually taking the blending mode into account. When I get a chance, I’ll do some more testing, and check the code to see if it’s actually using the selected blending mode at all.


That would be excellent, it’s a shame that Mypaint’s development is so slow.


MyPaint developing look like it’s really slow, one doesn’t know what’s going on there for over a year, I guess!
And that’s too bad @Brien_Dieterle stopped working at color-stuff there… so no strong achievement
in this context in MyPaint. :frowning: But on the other hand, Brien has started another interesting project,
his own paint-editor for iPad, named “Focal Paint”:

Take a look because it is very promising in terms of computer-color in nowadays graphics editors.
So you can read about it there:

“FocalPaint doesn’t use the traditional RGB or CMYK color models that most apps use. These models were designed for efficiency with little attempt to mimic real paints and media. FocalPaint pulls out all the stops and uses a 256 bits-per-pixel spectral model with 12 wavelengths representing the reflectance curves of natural pigments. These reflectance curves are blended using a weighted geometric mean algorithm to closely match the behavior of real paints and pigments. This is how blue and yellow create green in a realistic manner. Other programs might try to use HSV or other three-channel color models but the result is rarely convincing.”

So… Brien is da man! :slight_smile:
And I review his editor from time to time.
For a one-man project it is quite good! :sunglasses:


That’s my impression as well. As for blending mode, I am quite fond of “Geometric Mean” - use that quite often. It’d be great if the smudging would follow it.

FWIW: the bristle brush engine with “soak ink” enabled, does respect the blending mode. But the bristle brush has some issues - would love to see that one developed further.

I think this topic is already in discussion here:

You know what might be easy to implement and give an effect that achieve similar results.

A plugin that takes advantage of the Rad’s pack bundle clone picker brushes. (Edit wrote RZV bundle by mistake)
A mini canvas docker you paint in. With the ability to brighten, adjust color tint and save/load new & past color-pick-patterns you created.
and being able to shift up down left right. that way you can align you color picker with what’s in the docker just right.
Maybe make the color generator a built in tool - #3 by tachiko ](Maybe make the color generator a built in tool - #3 by tachiko)

I think focal paint is closed source though, So although it is mind blowing it won’t be any help for us to implement it in krita without looking at the code. As an for end user it is nice and I like to see its progress.

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Once again… There’s no secret to it. Krita used to have this years ago. You can still see the code in KDE - Experience Freedom!, in krita/plugins/extensions.

In the end, it just wasn’t useful enough to keep maintaining it.


I looked at the code some more, because I remembered including the current blending mode in some way when I created the initial version of the Lightness mode for the smudge engine, and it is in there. As it currently stands, the current blending mode is used only for how the chosen paint color is blended into the existing paint (based on color rate). It does not affect how existing colors on the canvas are blended together.

I could potentially update it to make the smudge mixing use the blending mode too, but there are a few things that complicate it. First thing is I would have to figure out how to handle the Smear Alpha option, because right now that option is implemented by changing the blending mode it uses.

Second thing is that if anyone has made any smudge brushes that use a different blending mode than Normal (e.g. Erase), those brushes would probably suddenly behave differently if the smudge mixing were changed to use the different blending mode. Because of that, I would have to add an option to use the blending mode for smudging or not. Not too big a deal, but it does make the smudge engine just a bit more complicated/confusing. I’m also curious if it would make sense to just allow the two blending stages to have any blending mode independent of each other, so there would be two separate blending mode options in the brush editor.

I’ll think about these things, and maybe if I find some free time do some testing to see if it could work. Because if we can get some more realistic mixing brushes, I think that would be pretty cool.