Please help me to understand "Channel Mixer"

thanks for tagging me! I love the RGB channels too; though I dislike the fact that you have to be careful when adding, that you have to also subtract an equal amount …or the balance is shifted. I wish we had a checkbox that did that for you. It is relevant to keep in mind that results will be different from HSV or HSL because those only work on the greens, while channel mixer will blueify all the green there is in the image, even in pixels that have 20% green 70% red and 10% blue.