With the Channel Mixer adjustment, you can individually adjust the Red, Green, and Blue channels in a photo. It’s one of the quickest and easiest ways to color-grade your images. Simply select the channel you want to work in and adjust just how much of that color tint you want to see in the red, green, and blue areas of a photo.
Tap and turn on Channel Mixer.
Tap to select the Red, Green, or Blue color channel.
Drag the sliders to the right to increase the amount of the red, green, or blue color tint in the red, green, or blue areas of an image.
Drag the sliders to the left to decrease the amount of the red, green, or blue color tint in the red, green, or blue areas of an image. Note that decreasing the amount of a particular color channel in a photo will add more of its complementary color to it.