Nice idea, though, I prefer old version.
Your description helps to orientate in the colour space, but it gives the impression that there are more than 3 basic colours, and distracts from the fact that cyan, magenta and yellow are only combinations (with the corresponding ratio) of red, green and blue.
I would like to give a short demonstration of how channel mixers could be used to remove color cast.
The photo I use for this is in this post:
This is what the photo looks like unprocessed. We have a strong yellowish tint in the room caused by the lighting. Also in the windows you can see purple coloration:
I suppose the light in the opposite room was white and I will first use the window area for white balance:
Now it has been corrected for the purple color cast and we can try to use the channel mixer to correct the yellow color cast as much as possible.
With color picker we first look for a place in the room where we know that it had to be grey but is illuminated by the yellow light. The surface of the white chair behind the girl, seems to be a good choice. We select it with the color picker and add the values to the list below:
Now we can read the color values there:
R = 163
G = 153
B = 86
We know from our color wheel…
… that yellow is a combination of red and green in the absence of blue which is confirmed in the values; red and green have similar values (163, 153) and the value for blue is very low (86).
That means, to remove yellow color cast, we have to increase the blue color channel by some amount of red and green.
Let’s start with red.
In the channel mixer we select blue as the destination and increase the red part of the blue channel. At the same time, we **reduce the blue part of the blue channel approximately ** by the amount we increased with red:
As you can see, the color has already improved. Now we increase the green part of the blue channel, but not as much as the red part, because it was originally also lower:
Now we have to make a few adjustments to adjust the ratio between red and green.
We choose green channel as destination and increase the red and green part of the green channel very subtly, so that the ratio stays about the same:
Now we go back to the blue channel and reduce the blue part of the blue channel very subtly to prevent that the yellow in the photo disappears completely:
Here is the result from before and after:
A note: In the picture there is another light source with purple light which illuminates the face of the woman and the girl. This can also be corrected with a new instance of the channel mixer. First these purple areas have to be masked
Here is the result after further processing steps:
