If you want an image to contribute to 100% to blue and 30% to green, you can associate a colour to it that contains 100% blue and 30% green, but it has to be done in hexadecimal currently in the custom colour window, something like #0064ff…
I can change the color ratios for RGB by adjusting the sliders marked in red for an individual color
But a) this is not precise and b) it only does for r,g,b channels, not the others or luminance.
So it does not help in the requirement of allocating x% of image to Y channel. Ideally there would be possibility of putting percentage numbers in the area highlighted in yellow.
So where do I put the hex numbers mentioned by Vincent?
Tutorial should be there tomorrow.
The weights depend on the colour you chose. A full red will give 100% of the associated image in the red channel of the result.
One suggestion - normally users may like to do the colors the other way - eg 30% of red from image A and 70% from Image B.
To do this, a table will have to be built, colors as rows and images as columns, with each column and row totaling to 100%. Then the colors for each image can be done based on that.
Is that something feasible to add to the tutorial, or do you think it would cause more confusion than clarity?
I do it the other way: which images do I want to contribute to red and how much? then set a colour to those images based on the answer. You should not set a 100% red to an image if you know you will have another image contributing to the red output.
I think you have a problem of consistency between the levels of your images or that you are trying to make a white balance with the wrong tool. You should just know what amount of each of the three colours you want to assign to each image, then do a white balance outside the tool maybe. And use the linear match as described in the first part of the tutorial.