Using the Channel Mixer adjustment, you can create high-quality grayscale, sepia tone, or other tinted images. You can also make creative color adjustments to an image. To create high-quality grayscale images, choose the percentage for each color channel in the Channel Mixer adjustment. To convert a color image to grayscale and add tinting to the image, use the Black & White command (see Convert a color image to black and white).
The Channel Mixer adjustment options modify a targeted (output) color channel using a mix of the existing (source) color channels in the image. Color channels are grayscale images representing the tonal values of the color components in an image (RGB or CMYK). When you use the Channel Mixer, you are adding or subtracting grayscale data from a source channel to the targeted channel. You are not adding or subtracting colors to a specific color component as you do with the Selective Color adjustment.
Channel Mixer presets are available from the Preset menu in the Properties panel (CC, CS6) or Adjustments panel (CS5). Use the default Channel Mixer presets to create, save, and load custom presets.