Channel effects are used to manipulate the channels in a layer, such as RGB or luminance.
Blurs channels individually. Useful for creating the impression of chromatic aberration.
Used to mix the color channels together. The red channel can have some of the blue channel introduced to it, for example.
Replaces channels with other channels. For example, you can have a layer's alpha (transparency) set to correspond to its red values, or its saturation. This is useful for both color grading and compositing.
Channel time shift
Moves red, green and blue channels backwards or forwards in time individually.