Generally the blending mode of the color picker, using the ctrl key, works fine. But when I try to mix yellow and blue the mixture of both colors turns not into a strong green but into a greyish value. This doesn´t happen with the color combinations blue and red or red and yellow. My presets in the tool options of the color picker are “50%” and “sample current layer”.
Does anyone have made the same experience? Is there any solution for this problem?
i think that’s the way color work : if you mix (equally) two opposite colors on the color ring, you will obtain a 50% grey color. And yellow/blue are exact opposite, they mute each other.
Digital painting uses an additive color model. In RGB color space the base colors are red, green and blue. As you can see green can not be created by mixing two colors like its done in a subtractive color model i.e. real paint.
Pure yellow and pure blue would give white as a result. Since your colors probably have some value too, they give gray instead.
More about additive color here
Thanks for your quick response, mco.
When I get you right, there is no way of mixing colors by picking in the way “real” paint works. I have to select colors from the color wheel or another color selector docker.
Thank you for your quick response, dear Takiro.
It seems - in the digital world - I have to forget the way mixing colors like I do in the “real” color world. In Ramons latest video about impressionistic painting I have got the impression that I could use digital brushes like analog ones. In future I will use the color dockers to define my color mixtures.
That’s correct, Krita doesn’t simulate analog color mixing.
Well, additive is just as real but image mixing light instead of pigments which makes sense since your screen emits colored light too and in the same way (and it turns out analog pigment like mixing is very hard to implement digitally). However mixing is still possible but the results are just different, we digital artist just learned to take this into account, it takes a while but then feels just as natural as analog mixing.
Thank you for your concluding clarifcation, halla. For weeks I tried different color models and color profiles, I even bought a new monitor. Such a simple answer to my problem. But, the new monitor is an improvement anyway 
Thanks for your explanation, Takiro!
I´m relieved that I haven´t to search for a failure in my equipment.
Your welcome. I remember when I first started getting into digital about 15 years ago because I thought it would be easier and then discovered how many new things I have to learn that are no issues and no-brainers in traditional painting (but the opposite is true too).
Dear Halla,
I have found a project were people try to simulate natural color mixing for digital painting. May be its a suggestion for you: https://dl.acm.org/doi/10.1145/3072959.3073690
There is also a video on this site. At timestamp 8:36 they show how to mix yellow and blue. Exactly the problem of my post. I am not a developer and the mathematical terms in this video are foreign words for me. I hope this project is interesting for you.
Yeah, we are already discussing natural color mixing a lot.
In that video it is mostly RGB mixing it is not really natural color mixing that is something much more annoying.
What differs there is the GUI for the blobs. You have also a have hsv interpolation at one point which is not the best if not noticably bad. I still think hcy mixing to be better even with it’s bad use cases stated on the previous discussion thread.
I have suggested index colors for recoloring like this before.
If I knew how to make non linear gradients and metaballs i would have done a picker like this already. This presentation was already under my radar however I am not sure how much of it is possible. Maybe qt6 might have metaballs? Donno.